ContentProvider原理分析二 MediaProvider publish .

本文仅讨论ContentProvider的Publish过程。

在Android启动后，会自动launch application，如果Application用到ContentProvider则会在handleBindApplication（）时publish该ContentProvider。另外如果ContentProvider进程中途死掉，则在有调用ContentProvider接口如query,update等时创建。本文即专注于此流程。

Application通过在AndroidManifest.xml中说明<provider android:name="MediaProvider" android.authority="media" android.multiprocess="false" />，则PackageManager可以知道对应ContentProvider的apk文件，从而加载该apk完成Contentprovider publish.

步骤：

通过ContentResolver先查找对应给定Uri的ContentProvider，返回对应的BinderProxy

a.通过ServiceManager查找activity service得到ActivityManagerService对应BinderProxy

b.调用BinderProxy的transcat方法发送GET_CONTENT_PROVIDER_TRANSACTION命令，得到对应ContentProvider的BinderProxy

一旦得到ActivityManager对应的binder 代理对象，则使用如下代码可以发送请求得到名字为name的Contentprovider。

调用顺序图:

源代码调用路径：

frameworks/base/core/java/android/app/ActivityManagerNative.java

class ActivityManagerProxy implements IActivityManager
{
...
    public ContentProviderHolder getContentProvider(IApplicationThread caller,
                                                    String name) throws RemoteException
    {
        Parcel data = Parcel.obtain();
        Parcel reply = Parcel.obtain();
        data.writeInterfaceToken(IActivityManager.descriptor);
        data.writeStrongBinder(caller != null ? caller.asBinder() : null);
        data.writeString(name);                                                   //ContentProvider名字
        mRemote.transact(GET_CONTENT_PROVIDER_TRANSACTION, data, reply, 0);       //取得ContentProvider
        reply.readException();
        int res = reply.readInt();
        ContentProviderHolder cph = null;
        if (res != 0) {
            cph = ContentProviderHolder.CREATOR.createFromParcel(reply);
        }
        data.recycle();
        reply.recycle();
        return cph;
    }

class ActivityManagerProxy implements IActivityManager
{
...
    public ContentProviderHolder getContentProvider(IApplicationThread caller,
                                                    String name) throws RemoteException
    {
        Parcel data = Parcel.obtain();
        Parcel reply = Parcel.obtain();
        data.writeInterfaceToken(IActivityManager.descriptor);
        data.writeStrongBinder(caller != null ? caller.asBinder() : null);
        data.writeString(name);                                                   //ContentProvider名字
        mRemote.transact(GET_CONTENT_PROVIDER_TRANSACTION, data, reply, 0);       //取得ContentProvider
        reply.readException();
        int res = reply.readInt();
        ContentProviderHolder cph = null;
        if (res != 0) {
            cph = ContentProviderHolder.CREATOR.createFromParcel(reply);
        }
        data.recycle();
        reply.recycle();
        return cph;
    }

frameworks/base/core/java/android/app/ActivityManagerService.java

    public final ContentProviderHolder getContentProvider(
            IApplicationThread caller, String name) {
        if (caller == null) {
            String msg = "null IApplicationThread when getting content provider "
                    + name;
            Slog.w(TAG, msg);
            throw new SecurityException(msg);
        }

        return getContentProviderImpl(caller, name);
    }
    private final ContentProviderHolder getContentProviderImpl(
        IApplicationThread caller, String name) {
        ContentProviderRecord cpr;
        ProviderInfo cpi = null;

        synchronized(this) {
            ProcessRecord r = null;
            if (caller != null) {
                r = getRecordForAppLocked(caller);
                if (r == null) {
                    throw new SecurityException(
                            "Unable to find app for caller " + caller
                          + " (pid=" + Binder.getCallingPid()
                          + ") when getting content provider " + name);
                }
            }

            // First check if this content provider has been published...
            cpr = mProvidersByName.get(name);
            if (cpr != null) {
...

            } else {
                try {
                    cpi = AppGlobals.getPackageManager().
                        resolveContentProvider(name,
                                STOCK_PM_FLAGS | PackageManager.GET_URI_PERMISSION_PATTERNS);
                } catch (RemoteException ex) {
                }
                if (cpi == null) {
                    return null;
                }

                String msg;
                if ((msg=checkContentProviderPermissionLocked(cpi, r)) != null) {
                    throw new SecurityException(msg);
                }

                if (!mProcessesReady && !mDidUpdate && !mWaitingUpdate
                        && !cpi.processName.equals("system")) {
                    // If this content provider does not run in the system
                    // process, and the system is not yet ready to run other
                    // processes, then fail fast instead of hanging.
                    throw new IllegalArgumentException(
                            "Attempt to launch content provider before system ready");
                }

                cpr = mProvidersByClass.get(cpi.name);
                final boolean firstClass = cpr == null;
                if (firstClass) {
                    try {
                        ApplicationInfo ai =
                            AppGlobals.getPackageManager().
                                getApplicationInfo(
                                        cpi.applicationInfo.packageName,
                                        STOCK_PM_FLAGS);
                        if (ai == null) {
                            Slog.w(TAG, "No package info for content provider "
                                    + cpi.name);
                            return null;
                        }
                        cpr = new ContentProviderRecord(cpi, ai);
                    } catch (RemoteException ex) {
                        // pm is in same process, this will never happen.
                    }
                }

                if (r != null && cpr.canRunHere(r)) {
                    // If this is a multiprocess provider, then just return its
                    // info and allow the caller to instantiate it.  Only do
                    // this if the provider is the same user as the caller's
                    // process, or can run as root (so can be in any process).
                    return cpr;
                }

                if (DEBUG_PROVIDER) {
                    RuntimeException e = new RuntimeException("here");
                    Slog.w(TAG, "LAUNCHING REMOTE PROVIDER (myuid " + r.info.uid
                          + " pruid " + cpr.appInfo.uid + "): " + cpr.info.name, e);
                }

                // This is single process, and our app is now connecting to it.
                // See if we are already in the process of launching this
                // provider.
                final int N = mLaunchingProviders.size();
                int i;
                for (i=0; i<N; i++) {
                    if (mLaunchingProviders.get(i) == cpr) {
                        break;
                    }
                }

                // If the provider is not already being launched, then get it
                // started.
                if (i >= N) {
                    final long origId = Binder.clearCallingIdentity();
                    ProcessRecord proc = startProcessLocked(cpi.processName,
                            cpr.appInfo, false, 0, "content provider",
                            new ComponentName(cpi.applicationInfo.packageName,
                                    cpi.name), false);
                    if (proc == null) {
                        Slog.w(TAG, "Unable to launch app "
                                + cpi.applicationInfo.packageName + "/"
                                + cpi.applicationInfo.uid + " for provider "
                                + name + ": process is bad");
                        return null;
                    }
                    cpr.launchingApp = proc;
                    mLaunchingProviders.add(cpr);
                    Binder.restoreCallingIdentity(origId);
                }

                // Make sure the provider is published (the same provider class
                // may be published under multiple names).
                if (firstClass) {
                    mProvidersByClass.put(cpi.name, cpr);
                }
                mProvidersByName.put(name, cpr);

                if (r != null) {
                    if (DEBUG_PROVIDER) Slog.v(TAG,
                            "Adding provider requested by "
                            + r.processName + " from process "
                            + cpr.info.processName);
                    Integer cnt = r.conProviders.get(cpr);
                    if (cnt == null) {
                        r.conProviders.put(cpr, new Integer(1));
                    } else {
                        r.conProviders.put(cpr, new Integer(cnt.intValue()+1));
                    }
                    cpr.clients.add(r);
                } else {
                    cpr.externals++;
                }
            }
        }

        // Wait for the provider to be published...
        synchronized (cpr) {
            while (cpr.provider == null) {
                if (cpr.launchingApp == null) {
                    Slog.w(TAG, "Unable to launch app "
                            + cpi.applicationInfo.packageName + "/"
                            + cpi.applicationInfo.uid + " for provider "
                            + name + ": launching app became null");
                    EventLog.writeEvent(EventLogTags.AM_PROVIDER_LOST_PROCESS,
                            cpi.applicationInfo.packageName,
                            cpi.applicationInfo.uid, name);
                    return null;
                }
                try {
                    cpr.wait();
                } catch (InterruptedException ex) {
                }
            }
        }
        return cpr;
    }
    final ProcessRecord startProcessLocked(String processName,
            ApplicationInfo info, boolean knownToBeDead, int intentFlags,
            String hostingType, ComponentName hostingName, boolean allowWhileBooting) {
        ProcessRecord app = getProcessRecordLocked(processName, info.uid);
        // We don't have to do anything more if:
        // (1) There is an existing application record; and
        // (2) The caller doesn't think it is dead, OR there is no thread
        //     object attached to it so we know it couldn't have crashed; and
        // (3) There is a pid assigned to it, so it is either starting or
        //     already running.
        if (DEBUG_PROCESSES) Slog.v(TAG, "startProcess: name=" + processName
                + " app=" + app + " knownToBeDead=" + knownToBeDead
                + " thread=" + (app != null ? app.thread : null)
                + " pid=" + (app != null ? app.pid : -1));
        if (app != null && app.pid > 0) {
            if (!knownToBeDead || app.thread == null) {
                // We already have the app running, or are waiting for it to
                // come up (we have a pid but not yet its thread), so keep it.
                if (DEBUG_PROCESSES) Slog.v(TAG, "App already running: " + app);
                return app;
            } else {
                // An application record is attached to a previous process,
                // clean it up now.
                if (DEBUG_PROCESSES) Slog.v(TAG, "App died: " + app);
                handleAppDiedLocked(app, true);
            }
        }

        String hostingNameStr = hostingName != null
                ? hostingName.flattenToShortString() : null;

        if ((intentFlags&Intent.FLAG_FROM_BACKGROUND) != 0) {
            // If we are in the background, then check to see if this process
            // is bad.  If so, we will just silently fail.
            if (mBadProcesses.get(info.processName, info.uid) != null) {
                if (DEBUG_PROCESSES) Slog.v(TAG, "Bad process: " + info.uid
                        + "/" + info.processName);
                return null;
            }
        } else {
            // When the user is explicitly starting a process, then clear its
            // crash count so that we won't make it bad until they see at
            // least one crash dialog again, and make the process good again
            // if it had been bad.
            if (DEBUG_PROCESSES) Slog.v(TAG, "Clearing bad process: " + info.uid
                    + "/" + info.processName);
            mProcessCrashTimes.remove(info.processName, info.uid);
            if (mBadProcesses.get(info.processName, info.uid) != null) {
                EventLog.writeEvent(EventLogTags.AM_PROC_GOOD, info.uid,
                        info.processName);
                mBadProcesses.remove(info.processName, info.uid);
                if (app != null) {
                    app.bad = false;
                }
            }
        }

        if (app == null) {
            app = newProcessRecordLocked(null, info, processName);
            mProcessNames.put(processName, info.uid, app);
        } else {
            // If this is a new package in the process, add the package to the list
            app.addPackage(info.packageName);
        }

        // If the system is not ready yet, then hold off on starting this
        // process until it is.
        if (!mProcessesReady
                && !isAllowedWhileBooting(info)
                && !allowWhileBooting) {
            if (!mProcessesOnHold.contains(app)) {
                mProcessesOnHold.add(app);
            }
            if (DEBUG_PROCESSES) Slog.v(TAG, "System not ready, putting on hold: " + app);
            return app;
        }

        startProcessLocked(app, hostingType, hostingNameStr);
        return (app.pid != 0) ? app : null;
    }

    public final ContentProviderHolder getContentProvider(
            IApplicationThread caller, String name) {
        if (caller == null) {
            String msg = "null IApplicationThread when getting content provider "
                    + name;
            Slog.w(TAG, msg);
            throw new SecurityException(msg);
        }

        return getContentProviderImpl(caller, name);
    }
    private final ContentProviderHolder getContentProviderImpl(
        IApplicationThread caller, String name) {
        ContentProviderRecord cpr;
        ProviderInfo cpi = null;

        synchronized(this) {
            ProcessRecord r = null;
            if (caller != null) {
                r = getRecordForAppLocked(caller);
                if (r == null) {
                    throw new SecurityException(
                            "Unable to find app for caller " + caller
                          + " (pid=" + Binder.getCallingPid()
                          + ") when getting content provider " + name);
                }
            }

            // First check if this content provider has been published...
            cpr = mProvidersByName.get(name);
            if (cpr != null) {
...

            } else {
                try {
                    cpi = AppGlobals.getPackageManager().
                        resolveContentProvider(name,
                                STOCK_PM_FLAGS | PackageManager.GET_URI_PERMISSION_PATTERNS);
                } catch (RemoteException ex) {
                }
                if (cpi == null) {
                    return null;
                }

                String msg;
                if ((msg=checkContentProviderPermissionLocked(cpi, r)) != null) {
                    throw new SecurityException(msg);
                }

                if (!mProcessesReady && !mDidUpdate && !mWaitingUpdate
                        && !cpi.processName.equals("system")) {
                    // If this content provider does not run in the system
                    // process, and the system is not yet ready to run other
                    // processes, then fail fast instead of hanging.
                    throw new IllegalArgumentException(
                            "Attempt to launch content provider before system ready");
                }
                
                cpr = mProvidersByClass.get(cpi.name);
                final boolean firstClass = cpr == null;
                if (firstClass) {
                    try {
                        ApplicationInfo ai =
                            AppGlobals.getPackageManager().
                                getApplicationInfo(
                                        cpi.applicationInfo.packageName,
                                        STOCK_PM_FLAGS);
                        if (ai == null) {
                            Slog.w(TAG, "No package info for content provider "
                                    + cpi.name);
                            return null;
                        }
                        cpr = new ContentProviderRecord(cpi, ai);
                    } catch (RemoteException ex) {
                        // pm is in same process, this will never happen.
                    }
                }

                if (r != null && cpr.canRunHere(r)) {
                    // If this is a multiprocess provider, then just return its
                    // info and allow the caller to instantiate it.  Only do
                    // this if the provider is the same user as the caller's
                    // process, or can run as root (so can be in any process).
                    return cpr;
                }

                if (DEBUG_PROVIDER) {
                    RuntimeException e = new RuntimeException("here");
                    Slog.w(TAG, "LAUNCHING REMOTE PROVIDER (myuid " + r.info.uid
                          + " pruid " + cpr.appInfo.uid + "): " + cpr.info.name, e);
                }

                // This is single process, and our app is now connecting to it.
                // See if we are already in the process of launching this
                // provider.
                final int N = mLaunchingProviders.size();
                int i;
                for (i=0; i<N; i++) {
                    if (mLaunchingProviders.get(i) == cpr) {
                        break;
                    }
                }

                // If the provider is not already being launched, then get it
                // started.
                if (i >= N) {
                    final long origId = Binder.clearCallingIdentity();
                    ProcessRecord proc = startProcessLocked(cpi.processName,
                            cpr.appInfo, false, 0, "content provider",
                            new ComponentName(cpi.applicationInfo.packageName,
                                    cpi.name), false);
                    if (proc == null) {
                        Slog.w(TAG, "Unable to launch app "
                                + cpi.applicationInfo.packageName + "/"
                                + cpi.applicationInfo.uid + " for provider "
                                + name + ": process is bad");
                        return null;
                    }
                    cpr.launchingApp = proc;
                    mLaunchingProviders.add(cpr);
                    Binder.restoreCallingIdentity(origId);
                }

                // Make sure the provider is published (the same provider class
                // may be published under multiple names).
                if (firstClass) {
                    mProvidersByClass.put(cpi.name, cpr);
                }
                mProvidersByName.put(name, cpr);

                if (r != null) {
                    if (DEBUG_PROVIDER) Slog.v(TAG,
                            "Adding provider requested by "
                            + r.processName + " from process "
                            + cpr.info.processName);
                    Integer cnt = r.conProviders.get(cpr);
                    if (cnt == null) {
                        r.conProviders.put(cpr, new Integer(1));
                    } else {
                        r.conProviders.put(cpr, new Integer(cnt.intValue()+1));
                    }
                    cpr.clients.add(r);
                } else {
                    cpr.externals++;
                }
            }
        }

        // Wait for the provider to be published...
        synchronized (cpr) {
            while (cpr.provider == null) {
                if (cpr.launchingApp == null) {
                    Slog.w(TAG, "Unable to launch app "
                            + cpi.applicationInfo.packageName + "/"
                            + cpi.applicationInfo.uid + " for provider "
                            + name + ": launching app became null");
                    EventLog.writeEvent(EventLogTags.AM_PROVIDER_LOST_PROCESS,
                            cpi.applicationInfo.packageName,
                            cpi.applicationInfo.uid, name);
                    return null;
                }
                try {
                    cpr.wait();
                } catch (InterruptedException ex) {
                }
            }
        }
        return cpr;
    }
    final ProcessRecord startProcessLocked(String processName,
            ApplicationInfo info, boolean knownToBeDead, int intentFlags,
            String hostingType, ComponentName hostingName, boolean allowWhileBooting) {
        ProcessRecord app = getProcessRecordLocked(processName, info.uid);
        // We don't have to do anything more if:
        // (1) There is an existing application record; and
        // (2) The caller doesn't think it is dead, OR there is no thread
        //     object attached to it so we know it couldn't have crashed; and
        // (3) There is a pid assigned to it, so it is either starting or
        //     already running.
        if (DEBUG_PROCESSES) Slog.v(TAG, "startProcess: name=" + processName
                + " app=" + app + " knownToBeDead=" + knownToBeDead
                + " thread=" + (app != null ? app.thread : null)
                + " pid=" + (app != null ? app.pid : -1));
        if (app != null && app.pid > 0) {
            if (!knownToBeDead || app.thread == null) {
                // We already have the app running, or are waiting for it to
                // come up (we have a pid but not yet its thread), so keep it.
                if (DEBUG_PROCESSES) Slog.v(TAG, "App already running: " + app);
                return app;
            } else {
                // An application record is attached to a previous process,
                // clean it up now.
                if (DEBUG_PROCESSES) Slog.v(TAG, "App died: " + app);
                handleAppDiedLocked(app, true);
            }
        }

        String hostingNameStr = hostingName != null
                ? hostingName.flattenToShortString() : null;
        
        if ((intentFlags&Intent.FLAG_FROM_BACKGROUND) != 0) {
            // If we are in the background, then check to see if this process
            // is bad.  If so, we will just silently fail.
            if (mBadProcesses.get(info.processName, info.uid) != null) {
                if (DEBUG_PROCESSES) Slog.v(TAG, "Bad process: " + info.uid
                        + "/" + info.processName);
                return null;
            }
        } else {
            // When the user is explicitly starting a process, then clear its
            // crash count so that we won't make it bad until they see at
            // least one crash dialog again, and make the process good again
            // if it had been bad.
            if (DEBUG_PROCESSES) Slog.v(TAG, "Clearing bad process: " + info.uid
                    + "/" + info.processName);
            mProcessCrashTimes.remove(info.processName, info.uid);
            if (mBadProcesses.get(info.processName, info.uid) != null) {
                EventLog.writeEvent(EventLogTags.AM_PROC_GOOD, info.uid,
                        info.processName);
                mBadProcesses.remove(info.processName, info.uid);
                if (app != null) {
                    app.bad = false;
                }
            }
        }
        
        if (app == null) {
            app = newProcessRecordLocked(null, info, processName);
            mProcessNames.put(processName, info.uid, app);
        } else {
            // If this is a new package in the process, add the package to the list
            app.addPackage(info.packageName);
        }

        // If the system is not ready yet, then hold off on starting this
        // process until it is.
        if (!mProcessesReady
                && !isAllowedWhileBooting(info)
                && !allowWhileBooting) {
            if (!mProcessesOnHold.contains(app)) {
                mProcessesOnHold.add(app);
            }
            if (DEBUG_PROCESSES) Slog.v(TAG, "System not ready, putting on hold: " + app);
            return app;
        }

        startProcessLocked(app, hostingType, hostingNameStr);
        return (app.pid != 0) ? app : null;
    }

startProcessLocked通过调用Process.start()用来创建新的进程，其随后调用[email protected], 通过socket通知[email protected]调用[email protected]，最后调用Zygote.forkAndSpecialize()来创建进程并调用handleChildProc，在其中调用ZygoteInit.invokeStaticMain。 详见http://blog.csdn.net/windskier/article/details/6417061。

frameworks/base/core/java/com/android/os/Process.java

    public static final int start(final String processClass,
                                  final String niceName,
                                  int uid, int gid, int[] gids,
                                  int debugFlags,
                                  String[] zygoteArgs)
    {
        if (supportsProcesses()) {
            try {
                return startViaZygote(processClass, niceName, uid, gid, gids,
                        debugFlags, zygoteArgs);
            } catch (ZygoteStartFailedEx ex) {
                Log.e(LOG_TAG,
                        "Starting VM process through Zygote failed");
                throw new RuntimeException(
                        "Starting VM process through Zygote failed", ex);
            }
        } ...
     }

    private static int startViaZygote(final String processClass,
                                  final String niceName,
                                  final int uid, final int gid,
                                  final int[] gids,
                                  int debugFlags,
                                  String[] extraArgs)
                                  throws ZygoteStartFailedEx {
        int pid;

        synchronized(Process.class) {
            ArrayList<String> argsForZygote = new ArrayList<String>();

            // --runtime-init, --setuid=, --setgid=,
            // and --setgroups= must go first
            argsForZygote.add("--runtime-init");
            argsForZygote.add("--setuid=" + uid);
            argsForZygote.add("--setgid=" + gid);
...

            // --setgroups is a comma-separated list
            if (gids != null && gids.length > 0) {
                StringBuilder sb = new StringBuilder();
                sb.append("--setgroups=");

                int sz = gids.length;
                for (int i = 0; i < sz; i++) {
                    if (i != 0) {
                        sb.append(',');
                    }
                    sb.append(gids[i]);
                }

                argsForZygote.add(sb.toString());
            }

            if (niceName != null) {
                argsForZygote.add("--nice-name=" + niceName);
            }

            argsForZygote.add(processClass);

            if (extraArgs != null) {
                for (String arg : extraArgs) {
                    argsForZygote.add(arg);
                }
            }

            pid = zygoteSendArgsAndGetPid(argsForZygote);  //写入到Zygote端口，触发创建进程
        }

    private static int zygoteSendArgsAndGetPid(ArrayList<String> args)
            throws ZygoteStartFailedEx {

        int pid;

        openZygoteSocketIfNeeded();  //打开Zygote端口

        try {
            /**
             * See com.android.internal.os.ZygoteInit.readArgumentList()
             * Presently the wire format to the zygote process is:
             * a) a count of arguments (argc, in essence)
             * b) a number of newline-separated argument strings equal to count
             *
             * After the zygote process reads these it will write the pid of
             * the child or -1 on failure.
             */

            sZygoteWriter.write(Integer.toString(args.size()));
            sZygoteWriter.newLine();

            int sz = args.size();
            for (int i = 0; i < sz; i++) {
                String arg = args.get(i);
                if (arg.indexOf('\n') >= 0) {
                    throw new ZygoteStartFailedEx(
                            "embedded newlines not allowed");
                }
                sZygoteWriter.write(arg);
                sZygoteWriter.newLine();
            }

            sZygoteWriter.flush(); //写入数据到端口

            // Should there be a timeout on this?
            pid = sZygoteInputStream.readInt();      //等待读端口数据，即进程完成创建

            if (pid < 0) {
                throw new ZygoteStartFailedEx("fork() failed");
            }
        } catch (IOException ex) {
            try {
                if (sZygoteSocket != null) {
                    sZygoteSocket.close();
                }
            } catch (IOException ex2) {
                // we're going to fail anyway
                Log.e(LOG_TAG,"I/O exception on routine close", ex2);
            }

            sZygoteSocket = null;

            throw new ZygoteStartFailedEx(ex);
        }

        return pid;
    }

    public static final int start(final String processClass,
                                  final String niceName,
                                  int uid, int gid, int[] gids,
                                  int debugFlags,
                                  String[] zygoteArgs)
    {
        if (supportsProcesses()) {
            try {
                return startViaZygote(processClass, niceName, uid, gid, gids,
                        debugFlags, zygoteArgs);
            } catch (ZygoteStartFailedEx ex) {
                Log.e(LOG_TAG,
                        "Starting VM process through Zygote failed");
                throw new RuntimeException(
                        "Starting VM process through Zygote failed", ex);
            }
        } ...
     }
 
    private static int startViaZygote(final String processClass,
                                  final String niceName,
                                  final int uid, final int gid,
                                  final int[] gids,
                                  int debugFlags,
                                  String[] extraArgs)
                                  throws ZygoteStartFailedEx {
        int pid;

        synchronized(Process.class) {
            ArrayList<String> argsForZygote = new ArrayList<String>();

            // --runtime-init, --setuid=, --setgid=,
            // and --setgroups= must go first
            argsForZygote.add("--runtime-init");
            argsForZygote.add("--setuid=" + uid);
            argsForZygote.add("--setgid=" + gid);
...
 
            // --setgroups is a comma-separated list
            if (gids != null && gids.length > 0) {
                StringBuilder sb = new StringBuilder();
                sb.append("--setgroups=");

                int sz = gids.length;
                for (int i = 0; i < sz; i++) {
                    if (i != 0) {
                        sb.append(',');
                    }
                    sb.append(gids[i]);
                }

                argsForZygote.add(sb.toString());
            }

            if (niceName != null) {
                argsForZygote.add("--nice-name=" + niceName);
            }

            argsForZygote.add(processClass);

            if (extraArgs != null) {
                for (String arg : extraArgs) {
                    argsForZygote.add(arg);
                }
            }
            
            pid = zygoteSendArgsAndGetPid(argsForZygote);  //写入到Zygote端口，触发创建进程
        }

    private static int zygoteSendArgsAndGetPid(ArrayList<String> args)
            throws ZygoteStartFailedEx {

        int pid;

        openZygoteSocketIfNeeded();  //打开Zygote端口

        try {
            /**
             * See com.android.internal.os.ZygoteInit.readArgumentList()
             * Presently the wire format to the zygote process is:
             * a) a count of arguments (argc, in essence)
             * b) a number of newline-separated argument strings equal to count
             *
             * After the zygote process reads these it will write the pid of
             * the child or -1 on failure.
             */

            sZygoteWriter.write(Integer.toString(args.size()));
            sZygoteWriter.newLine();

            int sz = args.size();
            for (int i = 0; i < sz; i++) {
                String arg = args.get(i);
                if (arg.indexOf('\n') >= 0) {
                    throw new ZygoteStartFailedEx(
                            "embedded newlines not allowed");
                }
                sZygoteWriter.write(arg);
                sZygoteWriter.newLine();
            }

            sZygoteWriter.flush(); //写入数据到端口

            // Should there be a timeout on this?
            pid = sZygoteInputStream.readInt();      //等待读端口数据，即进程完成创建

            if (pid < 0) {
                throw new ZygoteStartFailedEx("fork() failed");
            }
        } catch (IOException ex) {
            try {
                if (sZygoteSocket != null) {
                    sZygoteSocket.close();
                }
            } catch (IOException ex2) {
                // we're going to fail anyway
                Log.e(LOG_TAG,"I/O exception on routine close", ex2);
            }

            sZygoteSocket = null;

            throw new ZygoteStartFailedEx(ex);
        }

        return pid;
    }

frameworks/base/core/java/com/android/internal/os/ZygoteConnection.java

class ZygoteConnection {

    void run() throws ZygoteInit.MethodAndArgsCaller {
        int loopCount = ZygoteInit.GC_LOOP_COUNT;

        while (true) {
...
            if (runOnce()) {
                break;
            }
        }
    }

    boolean runOnce() throws ZygoteInit.MethodAndArgsCaller {
        String args[];
        Arguments parsedArgs = null;
        FileDescriptor[] descriptors;

        try {
            args = readArgumentList(); //监听Zygote端口等待创建进程命令，如无则阻塞
            descriptors = mSocket.getAncillaryFileDescriptors();
        } catch (IOException ex) {
            Log.w(TAG, "IOException on command socket " + ex.getMessage());
            closeSocket();
            return true;
        }
...
            pid = Zygote.forkAndSpecialize(parsedArgs.uid, parsedArgs.gid,
                    parsedArgs.gids, parsedArgs.debugFlags, rlimits); //这里调用fork创建进程
...
        if (pid == 0) {
            // in child
            handleChildProc(parsedArgs, descriptors, newStderr);
            // should never happen
            return true;
        } else { /* pid != 0 */
            // in parent...pid of < 0 means failure
            return handleParentProc(pid, descriptors, parsedArgs);
        }
    }

private void handleChildProc(Arguments parsedArgs, FileDescriptor[] descriptors, PrintStream newStderr) throws ZygoteInit.MethodAndArgsCaller {...
        if (parsedArgs.runtimeInit) {
            RuntimeInit.zygoteInit(parsedArgs.remainingArgs);
        }
... }

class ZygoteConnection {

    void run() throws ZygoteInit.MethodAndArgsCaller {
        int loopCount = ZygoteInit.GC_LOOP_COUNT;

        while (true) {
...
            if (runOnce()) {
                break;
            }
        }
    }

    boolean runOnce() throws ZygoteInit.MethodAndArgsCaller {
        String args[];
        Arguments parsedArgs = null;
        FileDescriptor[] descriptors;

        try {
            args = readArgumentList(); //监听Zygote端口等待创建进程命令，如无则阻塞
            descriptors = mSocket.getAncillaryFileDescriptors();
        } catch (IOException ex) {
            Log.w(TAG, "IOException on command socket " + ex.getMessage());
            closeSocket();
            return true;
        }
...
            pid = Zygote.forkAndSpecialize(parsedArgs.uid, parsedArgs.gid,
                    parsedArgs.gids, parsedArgs.debugFlags, rlimits); //这里调用fork创建进程
...
        if (pid == 0) {
            // in child
            handleChildProc(parsedArgs, descriptors, newStderr);
            // should never happen
            return true;
        } else { /* pid != 0 */
            // in parent...pid of < 0 means failure
            return handleParentProc(pid, descriptors, parsedArgs);
        }
    }

private void handleChildProc(Arguments parsedArgs, FileDescriptor[] descriptors, PrintStream newStderr) throws ZygoteInit.MethodAndArgsCaller {...
        if (parsedArgs.runtimeInit) {
            RuntimeInit.zygoteInit(parsedArgs.remainingArgs);
        }
... }

 

frameworks/base/core/java/com/android/internal/os/RuntimeInit.java

    public static final void zygoteInit(String[] argv)
            throws ZygoteInit.MethodAndArgsCaller {
        commonInit();
        zygoteInitNative();
...
        invokeStaticMain(startClass, startArgs);       //调用main方法
    }

    public static final void zygoteInit(String[] argv)
            throws ZygoteInit.MethodAndArgsCaller {
        commonInit();
        zygoteInitNative();
...
        invokeStaticMain(startClass, startArgs);       //调用main方法
    }

 

frameworks/base/core/jni/AndroidRuntime.cpp

static void com_android_internal_os_RuntimeInit_zygoteInit(JNIEnv* env, jobject clazz)
{
    gCurRuntime->onZygoteInit();
}

static void com_android_internal_os_RuntimeInit_zygoteInit(JNIEnv* env, jobject clazz)
{
    gCurRuntime->onZygoteInit();
}

frameworks/base/cmds/app_process/App_main.cpp

class AppRuntime : public AndroidRuntime{
    virtual void onZygoteInit()
    {
        sp<ProcessState> proc = ProcessState::self();
        if (proc->supportsProcesses()) {
            proc->startThreadPool();       //对于应用来讲，此处创建1个线程池以处理Binder事件。注意此处只有一个Loop，而Native mediaserver进程则创建了两个线程循环。
        }
    }

class AppRuntime : public AndroidRuntime{
    virtual void onZygoteInit()
    {
        sp<ProcessState> proc = ProcessState::self();
        if (proc->supportsProcesses()) {
            proc->startThreadPool();       //对于应用来讲，此处创建1个线程池以处理Binder事件。注意此处只有一个Loop，而Native mediaserver进程则创建了两个线程循环。
        }       
    }

frameworks/base/core/java/android/app/ActivityThread.java

    public static final void main(String[] args) {
        SamplingProfilerIntegration.start();

        Process.setArgV0("<pre-initialized>");

        Looper.prepareMainLooper();
        if (sMainThreadHandler == null) {
            sMainThreadHandler = new Handler();
        }

        ActivityThread thread = new ActivityThread();
        thread.attach(false);

        if (false) {
            Looper.myLooper().setMessageLogging(new
                    LogPrinter(Log.DEBUG, "ActivityThread"));
        }

        Looper.loop();

    private final void attach(boolean system) {
        sThreadLocal.set(this);
        mSystemThread = system;
        if (!system) {
            ViewRoot.addFirstDrawHandler(new Runnable() {
                public void run() {
                    ensureJitEnabled();
                }
            });
            android.ddm.DdmHandleAppName.setAppName("<pre-initialized>");
            RuntimeInit.setApplicationObject(mAppThread.asBinder());
            IActivityManager mgr = ActivityManagerNative.getDefault();
            try {
                mgr.attachApplication(mAppThread);
            } catch (RemoteException ex) {
            }
...
}

    public static final void main(String[] args) {
        SamplingProfilerIntegration.start();

        Process.setArgV0("<pre-initialized>");

        Looper.prepareMainLooper();
        if (sMainThreadHandler == null) {
            sMainThreadHandler = new Handler();
        }

        ActivityThread thread = new ActivityThread();
        thread.attach(false);

        if (false) {
            Looper.myLooper().setMessageLogging(new
                    LogPrinter(Log.DEBUG, "ActivityThread"));
        }

        Looper.loop();

    private final void attach(boolean system) {
        sThreadLocal.set(this);
        mSystemThread = system;
        if (!system) {
            ViewRoot.addFirstDrawHandler(new Runnable() {
                public void run() {
                    ensureJitEnabled();
                }
            });
            android.ddm.DdmHandleAppName.setAppName("<pre-initialized>");
            RuntimeInit.setApplicationObject(mAppThread.asBinder());
            IActivityManager mgr = ActivityManagerNative.getDefault();
            try {
                mgr.attachApplication(mAppThread);
            } catch (RemoteException ex) {
            }
...
}

frameworks/base/services/java/com/android/server/am/ActivityManagerService.java

public final void attachApplication(IApplicationThread thread) {
    synchronized (this) {
        int callingPid = Binder.getCallingPid();
        final long origId = Binder.clearCallingIdentity();
        attachApplicationLocked(thread, callingPid);
        Binder.restoreCallingIdentity(origId);
    }
}

private final boolean attachApplicationLocked(IApplicationThread thread,
        int pid) {

    // Find the application record that is being attached...  either via
    // the pid if we are running in multiple processes, or just pull the
    // next app record if we are emulating process with anonymous threads.
    ProcessRecord app;
    if (pid != MY_PID && pid >= 0) {
        synchronized (mPidsSelfLocked) {
            app = mPidsSelfLocked.get(pid);
        }
    } else if (mStartingProcesses.size() > 0) {
        app = mStartingProcesses.remove(0);
        app.setPid(pid);
    } else {
        app = null;
    }

    if (app == null) {
        Slog.w(TAG, "No pending application record for pid " + pid
                + " (IApplicationThread " + thread + "); dropping process");
        EventLog.writeEvent(EventLogTags.AM_DROP_PROCESS, pid);
        if (pid > 0 && pid != MY_PID) {
            Process.killProcess(pid);
        } else {
            try {
                thread.scheduleExit();
            } catch (Exception e) {
                // Ignore exceptions.
            }
        }
        return false;
    }

    // If this application record is still attached to a previous
    // process, clean it up now.
    if (app.thread != null) {
        handleAppDiedLocked(app, true);
    }

    // Tell the process all about itself.

    if (localLOGV) Slog.v(
            TAG, "Binding process pid " + pid + " to record " + app);

    String processName = app.processName;
    try {
        thread.asBinder().linkToDeath(new AppDeathRecipient(
                app, pid, thread), 0);
    } catch (RemoteException e) {
        app.resetPackageList();
        startProcessLocked(app, "link fail", processName);
        return false;
    }

    EventLog.writeEvent(EventLogTags.AM_PROC_BOUND, app.pid, app.processName);

    app.thread = thread;
    app.curAdj = app.setAdj = -100;
    app.curSchedGroup = Process.THREAD_GROUP_DEFAULT;
    app.setSchedGroup = Process.THREAD_GROUP_BG_NONINTERACTIVE;
    app.forcingToForeground = null;
    app.foregroundServices = false;
    app.debugging = false;

    mHandler.removeMessages(PROC_START_TIMEOUT_MSG, app);

    boolean normalMode = mProcessesReady || isAllowedWhileBooting(app.info);
    List providers = normalMode ? generateApplicationProvidersLocked(app) : null;

    if (!normalMode) {
        Slog.i(TAG, "Launching preboot mode app: " + app);
    }

    if (localLOGV) Slog.v(
        TAG, "New app record " + app
        + " thread=" + thread.asBinder() + " pid=" + pid);
    try {
        int testMode = IApplicationThread.DEBUG_OFF;
        if (mDebugApp != null && mDebugApp.equals(processName)) {
            testMode = mWaitForDebugger
                ? IApplicationThread.DEBUG_WAIT
                : IApplicationThread.DEBUG_ON;
            app.debugging = true;
            if (mDebugTransient) {
                mDebugApp = mOrigDebugApp;
                mWaitForDebugger = mOrigWaitForDebugger;
            }
        }

        // If the app is being launched for restore or full backup, set it up specially
        boolean isRestrictedBackupMode = false;
        if (mBackupTarget != null && mBackupAppName.equals(processName)) {
            isRestrictedBackupMode = (mBackupTarget.backupMode == BackupRecord.RESTORE)
                    || (mBackupTarget.backupMode == BackupRecord.BACKUP_FULL);
        }

        ensurePackageDexOpt(app.instrumentationInfo != null
                ? app.instrumentationInfo.packageName
                : app.info.packageName);
        if (app.instrumentationClass != null) {
            ensurePackageDexOpt(app.instrumentationClass.getPackageName());
        }
        if (DEBUG_CONFIGURATION) Slog.v(TAG, "Binding proc "
                + processName + " with config " + mConfiguration);
        thread.bindApplication(processName, app.instrumentationInfo != null
                ? app.instrumentationInfo : app.info, providers,
                app.instrumentationClass, app.instrumentationProfileFile,
                app.instrumentationArguments, app.instrumentationWatcher, testMode,
                isRestrictedBackupMode || !normalMode,
                mConfiguration, getCommonServicesLocked());
        updateLruProcessLocked(app, false, true);
        app.lastRequestedGc = app.lastLowMemory = SystemClock.uptimeMillis();
    } catch (Exception e) {
        // todo: Yikes!  What should we do?  For now we will try to
        // start another process, but that could easily get us in
        // an infinite loop of restarting processes...
        Slog.w(TAG, "Exception thrown during bind!", e);

        app.resetPackageList();
        startProcessLocked(app, "bind fail", processName);
        return false;
    }

    // Remove this record from the list of starting applications.
    mPersistentStartingProcesses.remove(app);
    if (DEBUG_PROCESSES && mProcessesOnHold.contains(app)) Slog.v(TAG,
            "Attach application locked removing on hold: " + app);
    mProcessesOnHold.remove(app);

    boolean badApp = false;
    boolean didSomething = false;

    // See if the top visible activity is waiting to run in this process...
    ActivityRecord hr = mMainStack.topRunningActivityLocked(null);
    if (hr != null && normalMode) {
        if (hr.app == null && app.info.uid == hr.info.applicationInfo.uid
                && processName.equals(hr.processName)) {
            try {
                if (mMainStack.realStartActivityLocked(hr, app, true, true)) {
                    didSomething = true;
                }
            } catch (Exception e) {
                Slog.w(TAG, "Exception in new application when starting activity "
                      + hr.intent.getComponent().flattenToShortString(), e);
                badApp = true;
            }
        } else {
            mMainStack.ensureActivitiesVisibleLocked(hr, null, processName, 0);
        }
    }

    // Find any services that should be running in this process...
    if (!badApp && mPendingServices.size() > 0) {
        ServiceRecord sr = null;
        try {
            for (int i=0; i<mPendingServices.size(); i++) {
                sr = mPendingServices.get(i);
                if (app.info.uid != sr.appInfo.uid
                        || !processName.equals(sr.processName)) {
                    continue;
                }

                mPendingServices.remove(i);
                i--;
                realStartServiceLocked(sr, app);
                didSomething = true;
            }
        } catch (Exception e) {
            Slog.w(TAG, "Exception in new application when starting service "
                  + sr.shortName, e);
            badApp = true;
        }
    }

    // Check if the next broadcast receiver is in this process...
    BroadcastRecord br = mPendingBroadcast;
    if (!badApp && br != null && br.curApp == app) {
        try {
            mPendingBroadcast = null;
            processCurBroadcastLocked(br, app);
            didSomething = true;
        } catch (Exception e) {
            Slog.w(TAG, "Exception in new application when starting receiver "
                  + br.curComponent.flattenToShortString(), e);
            badApp = true;
            logBroadcastReceiverDiscardLocked(br);
            finishReceiverLocked(br.receiver, br.resultCode, br.resultData,
                    br.resultExtras, br.resultAbort, true);
            scheduleBroadcastsLocked();
            // We need to reset the state if we fails to start the receiver.
            br.state = BroadcastRecord.IDLE;
        }
    }

    // Check whether the next backup agent is in this process...
    if (!badApp && mBackupTarget != null && mBackupTarget.appInfo.uid == app.info.uid) {
        if (DEBUG_BACKUP) Slog.v(TAG, "New app is backup target, launching agent for " + app);
        ensurePackageDexOpt(mBackupTarget.appInfo.packageName);
        try {
            thread.scheduleCreateBackupAgent(mBackupTarget.appInfo, mBackupTarget.backupMode);
        } catch (Exception e) {
            Slog.w(TAG, "Exception scheduling backup agent creation: ");
            e.printStackTrace();
        }
    }

    if (badApp) {
        // todo: Also need to kill application to deal with all
        // kinds of exceptions.
        handleAppDiedLocked(app, false);
        return false;
    }

    if (!didSomething) {
        updateOomAdjLocked();
    }

    return true;
}

    public final void attachApplication(IApplicationThread thread) {
        synchronized (this) {
            int callingPid = Binder.getCallingPid();
            final long origId = Binder.clearCallingIdentity();
            attachApplicationLocked(thread, callingPid);
            Binder.restoreCallingIdentity(origId);
        }
    }

    private final boolean attachApplicationLocked(IApplicationThread thread,
            int pid) {

        // Find the application record that is being attached...  either via
        // the pid if we are running in multiple processes, or just pull the
        // next app record if we are emulating process with anonymous threads.
        ProcessRecord app;
        if (pid != MY_PID && pid >= 0) {
            synchronized (mPidsSelfLocked) {
                app = mPidsSelfLocked.get(pid);
            }
        } else if (mStartingProcesses.size() > 0) {
            app = mStartingProcesses.remove(0);
            app.setPid(pid);
        } else {
            app = null;
        }

        if (app == null) {
            Slog.w(TAG, "No pending application record for pid " + pid
                    + " (IApplicationThread " + thread + "); dropping process");
            EventLog.writeEvent(EventLogTags.AM_DROP_PROCESS, pid);
            if (pid > 0 && pid != MY_PID) {
                Process.killProcess(pid);
            } else {
                try {
                    thread.scheduleExit();
                } catch (Exception e) {
                    // Ignore exceptions.
                }
            }
            return false;
        }

        // If this application record is still attached to a previous
        // process, clean it up now.
        if (app.thread != null) {
            handleAppDiedLocked(app, true);
        }

        // Tell the process all about itself.

        if (localLOGV) Slog.v(
                TAG, "Binding process pid " + pid + " to record " + app);

        String processName = app.processName;
        try {
            thread.asBinder().linkToDeath(new AppDeathRecipient(
                    app, pid, thread), 0);
        } catch (RemoteException e) {
            app.resetPackageList();
            startProcessLocked(app, "link fail", processName);
            return false;
        }

        EventLog.writeEvent(EventLogTags.AM_PROC_BOUND, app.pid, app.processName);
        
        app.thread = thread;
        app.curAdj = app.setAdj = -100;
        app.curSchedGroup = Process.THREAD_GROUP_DEFAULT;
        app.setSchedGroup = Process.THREAD_GROUP_BG_NONINTERACTIVE;
        app.forcingToForeground = null;
        app.foregroundServices = false;
        app.debugging = false;

        mHandler.removeMessages(PROC_START_TIMEOUT_MSG, app);

        boolean normalMode = mProcessesReady || isAllowedWhileBooting(app.info);
        List providers = normalMode ? generateApplicationProvidersLocked(app) : null;

        if (!normalMode) {
            Slog.i(TAG, "Launching preboot mode app: " + app);
        }
        
        if (localLOGV) Slog.v(
            TAG, "New app record " + app
            + " thread=" + thread.asBinder() + " pid=" + pid);
        try {
            int testMode = IApplicationThread.DEBUG_OFF;
            if (mDebugApp != null && mDebugApp.equals(processName)) {
                testMode = mWaitForDebugger
                    ? IApplicationThread.DEBUG_WAIT
                    : IApplicationThread.DEBUG_ON;
                app.debugging = true;
                if (mDebugTransient) {
                    mDebugApp = mOrigDebugApp;
                    mWaitForDebugger = mOrigWaitForDebugger;
                }
            }
            
            // If the app is being launched for restore or full backup, set it up specially
            boolean isRestrictedBackupMode = false;
            if (mBackupTarget != null && mBackupAppName.equals(processName)) {
                isRestrictedBackupMode = (mBackupTarget.backupMode == BackupRecord.RESTORE)
                        || (mBackupTarget.backupMode == BackupRecord.BACKUP_FULL);
            }
            
            ensurePackageDexOpt(app.instrumentationInfo != null
                    ? app.instrumentationInfo.packageName
                    : app.info.packageName);
            if (app.instrumentationClass != null) {
                ensurePackageDexOpt(app.instrumentationClass.getPackageName());
            }
            if (DEBUG_CONFIGURATION) Slog.v(TAG, "Binding proc "
                    + processName + " with config " + mConfiguration);
            thread.bindApplication(processName, app.instrumentationInfo != null
                    ? app.instrumentationInfo : app.info, providers,
                    app.instrumentationClass, app.instrumentationProfileFile,
                    app.instrumentationArguments, app.instrumentationWatcher, testMode, 
                    isRestrictedBackupMode || !normalMode,
                    mConfiguration, getCommonServicesLocked());
            updateLruProcessLocked(app, false, true);
            app.lastRequestedGc = app.lastLowMemory = SystemClock.uptimeMillis();
        } catch (Exception e) {
            // todo: Yikes!  What should we do?  For now we will try to
            // start another process, but that could easily get us in
            // an infinite loop of restarting processes...
            Slog.w(TAG, "Exception thrown during bind!", e);

            app.resetPackageList();
            startProcessLocked(app, "bind fail", processName);
            return false;
        }

        // Remove this record from the list of starting applications.
        mPersistentStartingProcesses.remove(app);
        if (DEBUG_PROCESSES && mProcessesOnHold.contains(app)) Slog.v(TAG,
                "Attach application locked removing on hold: " + app);
        mProcessesOnHold.remove(app);

        boolean badApp = false;
        boolean didSomething = false;

        // See if the top visible activity is waiting to run in this process...
        ActivityRecord hr = mMainStack.topRunningActivityLocked(null);
        if (hr != null && normalMode) {
            if (hr.app == null && app.info.uid == hr.info.applicationInfo.uid
                    && processName.equals(hr.processName)) {
                try {
                    if (mMainStack.realStartActivityLocked(hr, app, true, true)) {
                        didSomething = true;
                    }
                } catch (Exception e) {
                    Slog.w(TAG, "Exception in new application when starting activity "
                          + hr.intent.getComponent().flattenToShortString(), e);
                    badApp = true;
                }
            } else {
                mMainStack.ensureActivitiesVisibleLocked(hr, null, processName, 0);
            }
        }

        // Find any services that should be running in this process...
        if (!badApp && mPendingServices.size() > 0) {
            ServiceRecord sr = null;
            try {
                for (int i=0; i<mPendingServices.size(); i++) {
                    sr = mPendingServices.get(i);
                    if (app.info.uid != sr.appInfo.uid
                            || !processName.equals(sr.processName)) {
                        continue;
                    }

                    mPendingServices.remove(i);
                    i--;
                    realStartServiceLocked(sr, app);
                    didSomething = true;
                }
            } catch (Exception e) {
                Slog.w(TAG, "Exception in new application when starting service "
                      + sr.shortName, e);
                badApp = true;
            }
        }

        // Check if the next broadcast receiver is in this process...
        BroadcastRecord br = mPendingBroadcast;
        if (!badApp && br != null && br.curApp == app) {
            try {
                mPendingBroadcast = null;
                processCurBroadcastLocked(br, app);
                didSomething = true;
            } catch (Exception e) {
                Slog.w(TAG, "Exception in new application when starting receiver "
                      + br.curComponent.flattenToShortString(), e);
                badApp = true;
                logBroadcastReceiverDiscardLocked(br);
                finishReceiverLocked(br.receiver, br.resultCode, br.resultData,
                        br.resultExtras, br.resultAbort, true);
                scheduleBroadcastsLocked();
                // We need to reset the state if we fails to start the receiver.
                br.state = BroadcastRecord.IDLE;
            }
        }

        // Check whether the next backup agent is in this process...
        if (!badApp && mBackupTarget != null && mBackupTarget.appInfo.uid == app.info.uid) {
            if (DEBUG_BACKUP) Slog.v(TAG, "New app is backup target, launching agent for " + app);
            ensurePackageDexOpt(mBackupTarget.appInfo.packageName);
            try {
                thread.scheduleCreateBackupAgent(mBackupTarget.appInfo, mBackupTarget.backupMode);
            } catch (Exception e) {
                Slog.w(TAG, "Exception scheduling backup agent creation: ");
                e.printStackTrace();
            }
        }

        if (badApp) {
            // todo: Also need to kill application to deal with all
            // kinds of exceptions.
            handleAppDiedLocked(app, false);
            return false;
        }

        if (!didSomething) {
            updateOomAdjLocked();
        }

        return true;
    }

 

frameworks/base/core/java/android/app/ActivityThread.java

private final class ApplicationThread extends ApplicationThreadNative {
     public final void bindApplication(String processName,
             ApplicationInfo appInfo, List<ProviderInfo> providers,
             ComponentName instrumentationName, String profileFile,
             Bundle instrumentationArgs, IInstrumentationWatcher instrumentationWatcher,
             int debugMode, boolean isRestrictedBackupMode, Configuration config,
             Map<String, IBinder> services) {

         if (services != null) {
             // Setup the service cache in the ServiceManager
             ServiceManager.initServiceCache(services);
         }

         AppBindData data = new AppBindData();
         data.processName = processName;
         data.appInfo = appInfo;
         data.providers = providers;
         data.instrumentationName = instrumentationName;
         data.profileFile = profileFile;
         data.instrumentationArgs = instrumentationArgs;
         data.instrumentationWatcher = instrumentationWatcher;
         data.debugMode = debugMode;
         data.restrictedBackupMode = isRestrictedBackupMode;
         data.config = config;
         queueOrSendMessage(H.BIND_APPLICATION, data);
     }

   private final class ApplicationThread extends ApplicationThreadNative {
        public final void bindApplication(String processName,
                ApplicationInfo appInfo, List<ProviderInfo> providers,
                ComponentName instrumentationName, String profileFile,
                Bundle instrumentationArgs, IInstrumentationWatcher instrumentationWatcher,
                int debugMode, boolean isRestrictedBackupMode, Configuration config,
                Map<String, IBinder> services) {

            if (services != null) {
                // Setup the service cache in the ServiceManager
                ServiceManager.initServiceCache(services);
            }

            AppBindData data = new AppBindData();
            data.processName = processName;
            data.appInfo = appInfo;
            data.providers = providers;
            data.instrumentationName = instrumentationName;
            data.profileFile = profileFile;
            data.instrumentationArgs = instrumentationArgs;
            data.instrumentationWatcher = instrumentationWatcher;
            data.debugMode = debugMode;
            data.restrictedBackupMode = isRestrictedBackupMode;
            data.config = config;
            queueOrSendMessage(H.BIND_APPLICATION, data);
        }

 

public void handleMessage(Message msg) {

        case BIND_APPLICATION:
            AppBindData data = (AppBindData)msg.obj;
            handleBindApplication(data);
            break;

        public void handleMessage(Message msg) {
...
                case BIND_APPLICATION:
                    AppBindData data = (AppBindData)msg.obj;
                    handleBindApplication(data);
                    break;

 

private final void handleBindApplication(AppBindData data) {
    mBoundApplication = data;
    mConfiguration = new Configuration(data.config);

    // send up app name; do this *before* waiting for debugger
    Process.setArgV0(data.processName);
    android.ddm.DdmHandleAppName.setAppName(data.processName);

    /*
     * Before spawning a new process, reset the time zone to be the system time zone.
     * This needs to be done because the system time zone could have changed after the
     * the spawning of this process. Without doing this this process would have the incorrect
     * system time zone.
     */
    TimeZone.setDefault(null);

    /*
     * Initialize the default locale in this process for the reasons we set the time zone.
     */
    Locale.setDefault(data.config.locale);

    /*
     * Update the system configuration since its preloaded and might not
     * reflect configuration changes. The configuration object passed
     * in AppBindData can be safely assumed to be up to date
     */
    Resources.getSystem().updateConfiguration(mConfiguration, null);

    data.info = getPackageInfoNoCheck(data.appInfo);

    /**
     * For system applications on userdebug/eng builds, log stack
     * traces of disk and network access to dropbox for analysis.
     */
    if ((data.appInfo.flags &
         (ApplicationInfo.FLAG_SYSTEM |
          ApplicationInfo.FLAG_UPDATED_SYSTEM_APP)) != 0) {
        StrictMode.conditionallyEnableDebugLogging();
    }

    /**
     * Switch this process to density compatibility mode if needed.
     */
    if ((data.appInfo.flags&ApplicationInfo.FLAG_SUPPORTS_SCREEN_DENSITIES)
            == 0) {
        Bitmap.setDefaultDensity(DisplayMetrics.DENSITY_DEFAULT);
    }

    if (data.debugMode != IApplicationThread.DEBUG_OFF) {
        // XXX should have option to change the port.
        Debug.changeDebugPort(8100);
        if (data.debugMode == IApplicationThread.DEBUG_WAIT) {
            Slog.w(TAG, "Application " + data.info.getPackageName()
                  + " is waiting for the debugger on port 8100...");

            IActivityManager mgr = ActivityManagerNative.getDefault();
            try {
                mgr.showWaitingForDebugger(mAppThread, true);
            } catch (RemoteException ex) {
            }

            Debug.waitForDebugger();

            try {
                mgr.showWaitingForDebugger(mAppThread, false);
            } catch (RemoteException ex) {
            }

        } else {
            Slog.w(TAG, "Application " + data.info.getPackageName()
                  + " can be debugged on port 8100...");
        }
    }

    if (data.instrumentationName != null) {
        ContextImpl appContext = new ContextImpl();
        appContext.init(data.info, null, this);
        InstrumentationInfo ii = null;
        try {
            ii = appContext.getPackageManager().
                getInstrumentationInfo(data.instrumentationName, 0);
        } catch (PackageManager.NameNotFoundException e) {
        }
        if (ii == null) {
            throw new RuntimeException(
                "Unable to find instrumentation info for: "
                + data.instrumentationName);
        }

        mInstrumentationAppDir = ii.sourceDir;
        mInstrumentationAppPackage = ii.packageName;
        mInstrumentedAppDir = data.info.getAppDir();

        ApplicationInfo instrApp = new ApplicationInfo();
        instrApp.packageName = ii.packageName;
        instrApp.sourceDir = ii.sourceDir;
        instrApp.publicSourceDir = ii.publicSourceDir;
        instrApp.dataDir = ii.dataDir;
        instrApp.nativeLibraryDir = ii.nativeLibraryDir;
        LoadedApk pi = getPackageInfo(instrApp,
                appContext.getClassLoader(), false, true);
        ContextImpl instrContext = new ContextImpl();
        instrContext.init(pi, null, this);

        try {
            java.lang.ClassLoader cl = instrContext.getClassLoader();
            mInstrumentation = (Instrumentation)
                cl.loadClass(data.instrumentationName.getClassName()).newInstance();
        } catch (Exception e) {
            throw new RuntimeException(
                "Unable to instantiate instrumentation "
                + data.instrumentationName + ": " + e.toString(), e);
        }

        mInstrumentation.init(this, instrContext, appContext,
                new ComponentName(ii.packageName, ii.name), data.instrumentationWatcher);

        if (data.profileFile != null && !ii.handleProfiling) {
            data.handlingProfiling = true;
            File file = new File(data.profileFile);
            file.getParentFile().mkdirs();
            Debug.startMethodTracing(file.toString(), 8 * 1024 * 1024);
        }

        try {
            mInstrumentation.onCreate(data.instrumentationArgs);
        }
        catch (Exception e) {
            throw new RuntimeException(
                "Exception thrown in onCreate() of "
                + data.instrumentationName + ": " + e.toString(), e);
        }

    } else {
        mInstrumentation = new Instrumentation();
    }

    // If the app is being launched for full backup or restore, bring it up in
    // a restricted environment with the base application class.
    Application app = data.info.makeApplication(data.restrictedBackupMode, null);
    mInitialApplication = app;

    List<ProviderInfo> providers = data.providers;
    if (providers != null) {
        installContentProviders(app, providers);
        // For process that contain content providers, we want to
        // ensure that the JIT is enabled "at some point".
        mH.sendEmptyMessageDelayed(H.ENABLE_JIT, 10*1000);
    }

    try {
        mInstrumentation.callApplicationOnCreate(app);
    } catch (Exception e) {
        if (!mInstrumentation.onException(app, e)) {
            throw new RuntimeException(
                "Unable to create application " + app.getClass().getName()
                + ": " + e.toString(), e);
        }
    }
}

    private final void handleBindApplication(AppBindData data) {
        mBoundApplication = data;
        mConfiguration = new Configuration(data.config);

        // send up app name; do this *before* waiting for debugger
        Process.setArgV0(data.processName);
        android.ddm.DdmHandleAppName.setAppName(data.processName);

        /*
         * Before spawning a new process, reset the time zone to be the system time zone.
         * This needs to be done because the system time zone could have changed after the
         * the spawning of this process. Without doing this this process would have the incorrect
         * system time zone.
         */
        TimeZone.setDefault(null);

        /*
         * Initialize the default locale in this process for the reasons we set the time zone.
         */
        Locale.setDefault(data.config.locale);

        /*
         * Update the system configuration since its preloaded and might not
         * reflect configuration changes. The configuration object passed
         * in AppBindData can be safely assumed to be up to date
         */
        Resources.getSystem().updateConfiguration(mConfiguration, null);

        data.info = getPackageInfoNoCheck(data.appInfo);

        /**
         * For system applications on userdebug/eng builds, log stack
         * traces of disk and network access to dropbox for analysis.
         */
        if ((data.appInfo.flags &
             (ApplicationInfo.FLAG_SYSTEM |
              ApplicationInfo.FLAG_UPDATED_SYSTEM_APP)) != 0) {
            StrictMode.conditionallyEnableDebugLogging();
        }

        /**
         * Switch this process to density compatibility mode if needed.
         */
        if ((data.appInfo.flags&ApplicationInfo.FLAG_SUPPORTS_SCREEN_DENSITIES)
                == 0) {
            Bitmap.setDefaultDensity(DisplayMetrics.DENSITY_DEFAULT);
        }

        if (data.debugMode != IApplicationThread.DEBUG_OFF) {
            // XXX should have option to change the port.
            Debug.changeDebugPort(8100);
            if (data.debugMode == IApplicationThread.DEBUG_WAIT) {
                Slog.w(TAG, "Application " + data.info.getPackageName()
                      + " is waiting for the debugger on port 8100...");

                IActivityManager mgr = ActivityManagerNative.getDefault();
                try {
                    mgr.showWaitingForDebugger(mAppThread, true);
                } catch (RemoteException ex) {
                }

                Debug.waitForDebugger();

                try {
                    mgr.showWaitingForDebugger(mAppThread, false);
                } catch (RemoteException ex) {
                }

            } else {
                Slog.w(TAG, "Application " + data.info.getPackageName()
                      + " can be debugged on port 8100...");
            }
        }

        if (data.instrumentationName != null) {
            ContextImpl appContext = new ContextImpl();
            appContext.init(data.info, null, this);
            InstrumentationInfo ii = null;
            try {
                ii = appContext.getPackageManager().
                    getInstrumentationInfo(data.instrumentationName, 0);
            } catch (PackageManager.NameNotFoundException e) {
            }
            if (ii == null) {
                throw new RuntimeException(
                    "Unable to find instrumentation info for: "
                    + data.instrumentationName);
            }

            mInstrumentationAppDir = ii.sourceDir;
            mInstrumentationAppPackage = ii.packageName;
            mInstrumentedAppDir = data.info.getAppDir();

            ApplicationInfo instrApp = new ApplicationInfo();
            instrApp.packageName = ii.packageName;
            instrApp.sourceDir = ii.sourceDir;
            instrApp.publicSourceDir = ii.publicSourceDir;
            instrApp.dataDir = ii.dataDir;
            instrApp.nativeLibraryDir = ii.nativeLibraryDir;
            LoadedApk pi = getPackageInfo(instrApp,
                    appContext.getClassLoader(), false, true);
            ContextImpl instrContext = new ContextImpl();
            instrContext.init(pi, null, this);

            try {
                java.lang.ClassLoader cl = instrContext.getClassLoader();
                mInstrumentation = (Instrumentation)
                    cl.loadClass(data.instrumentationName.getClassName()).newInstance();
            } catch (Exception e) {
                throw new RuntimeException(
                    "Unable to instantiate instrumentation "
                    + data.instrumentationName + ": " + e.toString(), e);
            }

            mInstrumentation.init(this, instrContext, appContext,
                    new ComponentName(ii.packageName, ii.name), data.instrumentationWatcher);

            if (data.profileFile != null && !ii.handleProfiling) {
                data.handlingProfiling = true;
                File file = new File(data.profileFile);
                file.getParentFile().mkdirs();
                Debug.startMethodTracing(file.toString(), 8 * 1024 * 1024);
            }

            try {
                mInstrumentation.onCreate(data.instrumentationArgs);
            }
            catch (Exception e) {
                throw new RuntimeException(
                    "Exception thrown in onCreate() of "
                    + data.instrumentationName + ": " + e.toString(), e);
            }

        } else {
            mInstrumentation = new Instrumentation();
        }

        // If the app is being launched for full backup or restore, bring it up in
        // a restricted environment with the base application class.
        Application app = data.info.makeApplication(data.restrictedBackupMode, null);
        mInitialApplication = app;

        List<ProviderInfo> providers = data.providers;
        if (providers != null) {
            installContentProviders(app, providers);
            // For process that contain content providers, we want to
            // ensure that the JIT is enabled "at some point".
            mH.sendEmptyMessageDelayed(H.ENABLE_JIT, 10*1000);
        }

        try {
            mInstrumentation.callApplicationOnCreate(app);
        } catch (Exception e) {
            if (!mInstrumentation.onException(app, e)) {
                throw new RuntimeException(
                    "Unable to create application " + app.getClass().getName()
                    + ": " + e.toString(), e);
            }
        }
    }

frameworks/base/core/java/android/content/ContentProvider.java

<PRE class=java name="code">  public void attachInfo(Context context, ProviderInfo info) {

        /*
         * Only allow it to be set once, so after the content service gives
         * this to us clients can't change it.
         */
        if (mContext == null) {
            mContext = context;
            mMyUid = Process.myUid();
            if (info != null) {
                setReadPermission(info.readPermission);
                setWritePermission(info.writePermission);
                setPathPermissions(info.pathPermissions);
                mExported = info.exported;
            }
            ContentProvider.this.onCreate();
        }
    }</PRE>
<PRE></PRE>
<P></P>
<PRE></PRE>
<P></P>
<P>frameworks/base/services/java/com/android/server/am/ActivityManagerService.java </P>
<P></P>
<P></P>
<PRE class=cpp name="code">    public final void publishContentProviders(IApplicationThread caller,
            List<ContentProviderHolder> providers) {
        if (providers == null) {
            return;
        }

        synchronized(this) {
            final ProcessRecord r = getRecordForAppLocked(caller);
            if (r == null) {
                throw new SecurityException(
                        "Unable to find app for caller " + caller
                      + " (pid=" + Binder.getCallingPid()
                      + ") when publishing content providers");
            }

            final long origId = Binder.clearCallingIdentity();

            final int N = providers.size();
            for (int i=0; i<N; i++) {
                ContentProviderHolder src = providers.get(i);
                if (src == null || src.info == null || src.provider == null) {
                    continue;
                }
                ContentProviderRecord dst = r.pubProviders.get(src.info.name);
                if (dst != null) {
                    mProvidersByClass.put(dst.info.name, dst);
                    String names[] = dst.info.authority.split(";");
                    for (int j = 0; j < names.length; j++) {
                        mProvidersByName.put(names[j], dst);
                    }

                    int NL = mLaunchingProviders.size();
                    int j;
                    for (j=0; j<NL; j++) {
                        if (mLaunchingProviders.get(j) == dst) {
                            mLaunchingProviders.remove(j);
                            j--;
                            NL--;
                        }
                    }
                    synchronized (dst) {
                        dst.provider = src.provider;
                        dst.app = r;
                        dst.notifyAll();
                    }
                    updateOomAdjLocked(r);
                }
            }

            Binder.restoreCallingIdentity(origId);
        }
    }
</PRE><BR>
<P></P>
<P>frameworks/base/core/java/android/app/ActivityThread.java</P>
<P></P>
<P><BR>
</P>
<PRE class=cpp name="code"><PRE class=java name="code">    private final void installContentProviders(
            Context context, List<ProviderInfo> providers) {
        final ArrayList<IActivityManager.ContentProviderHolder> results =
            new ArrayList<IActivityManager.ContentProviderHolder>();

        Iterator<ProviderInfo> i = providers.iterator();
        while (i.hasNext()) {
            ProviderInfo cpi = i.next();
            StringBuilder buf = new StringBuilder(128);
            buf.append("Pub ");
            buf.append(cpi.authority);
            buf.append(": ");
            buf.append(cpi.name);
            Log.i(TAG, buf.toString());
            IContentProvider cp = installProvider(context, null, cpi, false);
            if (cp != null) {
                IActivityManager.ContentProviderHolder cph =
                    new IActivityManager.ContentProviderHolder(cpi);
                cph.provider = cp;
                results.add(cph);
                // Don't ever unload this provider from the process.
                synchronized(mProviderMap) {
                    mProviderRefCountMap.put(cp.asBinder(), new ProviderRefCount(10000));
                }
            }
        }

        try {
            ActivityManagerNative.getDefault().publishContentProviders(
                getApplicationThread(), results);
        } catch (RemoteException ex) {
        }
    }
</PRE>
<PRE></PRE>
<P>In the following code,ContentProvider is instantiated.</P>
<P></P>
<PRE class=cpp name="code"><PRE class=java name="code">    private final IContentProvider installProvider(Context context,
            IContentProvider provider, ProviderInfo info, boolean noisy) {
        ContentProvider localProvider = null;
        if (provider == null) {
            if (noisy) {
                Slog.d(TAG, "Loading provider " + info.authority + ": "
                        + info.name);
            }
            Context c = null;
            ApplicationInfo ai = info.applicationInfo;
            if (context.getPackageName().equals(ai.packageName)) {
                c = context;
            } else if (mInitialApplication != null &&
                    mInitialApplication.getPackageName().equals(ai.packageName)) {
                c = mInitialApplication;
            } else {
                try {
                    c = context.createPackageContext(ai.packageName,
                            Context.CONTEXT_INCLUDE_CODE);
                } catch (PackageManager.NameNotFoundException e) {
                }
            }
            if (c == null) {
                Slog.w(TAG, "Unable to get context for package " +
                      ai.packageName +
                      " while loading content provider " +
                      info.name);
                return null;
            }
            try {
                final java.lang.ClassLoader cl = c.getClassLoader();
                localProvider = (ContentProvider)cl.
                    loadClass(info.name).newInstance();               //这里构造ContentProvider实例，例如:new MediaProvider
                provider = localProvider.getIContentProvider();       //得到对应的Binder操作实例
                if (provider == null) {
                    Slog.e(TAG, "Failed to instantiate class " +
                          info.name + " from sourceDir " +
                          info.applicationInfo.sourceDir);
                    return null;
                }
                if (Config.LOGV) Slog.v(
                    TAG, "Instantiating local provider " + info.name);
                // XXX Need to create the correct context for this provider.
                localProvider.attachInfo(c, info);          //在这里调用ContentProvider.attachInfo,那里调用onCreate开始初始化Provider
            } catch (java.lang.Exception e) {
                if (!mInstrumentation.onException(null, e)) {
                    throw new RuntimeException(
                            "Unable to get provider " + info.name
                            + ": " + e.toString(), e);
                }
                return null;
            }
        } else if (localLOGV) {
            Slog.v(TAG, "Installing external provider " + info.authority + ": "
                    + info.name);
        }

        synchronized (mProviderMap) {
            // Cache the pointer for the remote provider.
            String names[] = PATTERN_SEMICOLON.split(info.authority); //同一个ContentProvider可能支持多个authority
            for (int i=0; i<names.length; i++) { //对每一个authority,构建对应的ProviderClientRecord
                ProviderClientRecord pr = new ProviderClientRecord(names[i], provider,
                        localProvider);
                try {
                    provider.asBinder().linkToDeath(pr, 0);
                    mProviderMap.put(names[i], pr);
                } catch (RemoteException e) {
                    return null;
                }
            }
            if (localProvider != null) { //如果provider早已创建出来了
                mLocalProviders.put(provider.asBinder(),
                        new ProviderClientRecord(null, provider, localProvider));
            }
        }

        return provider;
    }</PRE>
<PRE></PRE>
<P></P>
<PRE></PRE>
frameworks/base/services/java/com/android/server/am/ActivityManagerService.java
<P></P>
<P></P>
<PRE class=cpp name="code"><PRE class=java name="code">    public final void publishContentProviders(IApplicationThread caller,
            List<ContentProviderHolder> providers) {
        if (providers == null) {
            return;
        }

        synchronized(this) {
            final ProcessRecord r = getRecordForAppLocked(caller);
            if (r == null) {
                throw new SecurityException(
                        "Unable to find app for caller " + caller
                      + " (pid=" + Binder.getCallingPid()
                      + ") when publishing content providers");
            }

            final long origId = Binder.clearCallingIdentity();

            final int N = providers.size();
            for (int i=0; i<N; i++) {
                ContentProviderHolder src = providers.get(i);
                if (src == null || src.info == null || src.provider == null) {
                    continue;
                }
                ContentProviderRecord dst = r.pubProviders.get(src.info.name);
                if (dst != null) {
                    mProvidersByClass.put(dst.info.name, dst);
                    String names[] = dst.info.authority.split(";");
                    for (int j = 0; j < names.length; j++) {
                        mProvidersByName.put(names[j], dst);
                    }

                    int NL = mLaunchingProviders.size();
                    int j;
                    for (j=0; j<NL; j++) {
                        if (mLaunchingProviders.get(j) == dst) {
                            mLaunchingProviders.remove(j);
                            j--;
                            NL--;
                        }
                    }
                    synchronized (dst) {
                        dst.provider = src.provider;
                        dst.app = r;
                        dst.notifyAll();
                    }
                    updateOomAdjLocked(r);
                }
            }

            Binder.restoreCallingIdentity(origId);
        }
    }</PRE>
<PRE></PRE>
<P></P>
<PRE></PRE>
<P></P>
<P><BR>
</P>
<P><BR>
</P>
<P><BR>
</P>
<P><BR>
</P>
<P><BR>
</P>
<BR>
<PRE></PRE>
<PRE></PRE>
<PRE></PRE>
<PRE></PRE>
<PRE></PRE>
<PRE></PRE>
<PRE></PRE>
<PRE></PRE>
<PRE></PRE>
<PRE></PRE>
<PRE></PRE>
<PRE></PRE>
<PRE></PRE>
<PRE></PRE>
<PRE></PRE>
<PRE></PRE>
<PRE></PRE>
<PRE></PRE>
<PRE></PRE>
<PRE></PRE>
<PRE></PRE>
<PRE></PRE>
<PRE></PRE>
<PRE></PRE>
<PRE></PRE>
<PRE></PRE>
<PRE></PRE>
<PRE></PRE>
<PRE></PRE>
<PRE></PRE>
<PRE></PRE>
<PRE></PRE>
<PRE></PRE>
<PRE></PRE>
<PRE></PRE>
<PRE></PRE>
<PRE></PRE>
<PRE></PRE>
<PRE></PRE>
<PRE></PRE>
<PRE></PRE>
<PRE></PRE>
<PRE></PRE>

</PRE></PRE></PRE>