android中dumpsys函数介绍与使用
dumpsys是系统中重要的函数，我们来看看它如何使用，都能dump出来一些什么东西
首先我们来看看dumpsys的源码，在4.1中，它在framework/native目录下面
frameworks/native/cmds/dumpsys/dumpsys.cpp
if (argc == 1) {
services = sm->listServices();
services.sort(sort_func);
args.add(String16("-a"));
} else {
services.add(String16(argv[1]));
for (int i=2; i<argc; i++) {
args.add(String16(argv[i]));
}
}
const size_t N = services.size();
if (N > 1) {
// first print a list of the current services
aout << "Currently running services:" << endl;
for (size_t i=0; i<N; i++) {
sp<IBinder> service = sm->checkService(services[i]);
if (service != NULL) {
aout << " " << services[i] << endl;
}
}
}
for (size_t i=0; i<N; i++) {
sp<IBinder> service = sm->checkService(services[i]);
if (service != NULL) {
if (N > 1) {//dump多个Service时，Service信息之间的分隔
aout << "------------------------------------------------------------"
"-------------------" << endl;
aout << "DUMP OF SERVICE " << services[i] << ":" << endl;
}
int err = service->dump(STDOUT_FILENO, args);
if (err != 0) {
aerr << "Error dumping service info: (" << strerror(err)
<< ") " << services[i] << endl;
}
} else {
aerr << "Can't find service: " << services[i] << endl;
}
}
我只会java，上面的代码还是留给大家自己阅读吧，我就不详细解释了……
如果参数个数=1，则在ServiceManager中查找注册的Service
否则查找指定的Service，并且将剩余参数传给Serivce
如果执行dumpsys命令，那么将会dump所有Service，每个Service之间会分隔开
如果dumpsys一个没有注册的Service，那么则提示找不到Service，比如：
# dumpsys adb
Can't find service: adb
那么我们到底都可以dump一些什么呢？
其实最简单的办法就是执行dumpsys，看看其结果，下面是我手机中执行的结果（HTCg14）
# dumpsys Currently running services: DeviceManager3LM Encryption3LMService HtcAppUsageStatsService SurfaceFlinger accessibility account activity alarm appwidget audio backup battery batteryinfo bluetooth bluetooth_a2dp bluetooth_hid bt_fm_management clipboard connectivity content country_detector cpuinfo device_policy devicestoragemonitor diskstats display drm.drmManager dropbox entropy gfxinfo hardware htc_checkin htchardware htctelephony htctelephonyinternal input_method iphonesubinfo isms location media.audio_flinger media.audio_policy media.camera media.player meminfo mount netpolicy netstats network_management notification package permission phone power samplingprofiler search secfirewall secloader sensorservice simphonebook sip statusbar stub_activity stub_audio stub_iphonesubinfo stub_isms stub_location stub_phone stub_telephony.registry telephony.registry textservices throttle uimode usagestats usb usbnet userbehavior vibrator wallpaper wifi wifip2p window ------------------------------------------------------------------------------- DUMP OF SERVICE DeviceManager3LM: ------------------------------------------------------------------------------- DUMP OF SERVICE Encryption3LMService:
由于dump service的log实在太长，我就截取了最前面的“Currently running services”和两个Service的dump信息
为什么DeviceManager3LM和Encryption3LMService后面没有内容？这和Service的内部实现有关，也许它只是写了一个空的dump函数，也许有什么其他条件。
这个问题一会再说，我们先看看这些Service都是在哪注册的
其中大部分Service都是在SystemServer中的main函数里注册的，它调用了一个叫init2的函数
public static final void init2() {
Slog.i(TAG, "Entered the Android system server!");
Thread thr = new ServerThread();
thr.setName("android.server.ServerThread");
thr.start();
}
init2非常简单，所有任务都交给新线程ServerThread来处理
在ServerThread的run函数中，注册了系统大部分的Service，有兴趣的同学可以看看这部分代码
这部分代码有点长（大概800行），因为它一直重复这建立各种Service，然后注册，输出log
比如下面的WifiP2pService
try {
Slog.i(TAG, "Wi-Fi P2pService");
wifiP2p = new WifiP2pService(context);
ServiceManager.addService(Context.WIFI_P2P_SERVICE, wifiP2p);
} catch (Throwable e) {
reportWtf("starting Wi-Fi P2pService", e);
}
其中WIFI_P2P_SERVICE就是服务的名字
public static final String WIFI_P2P_SERVICE = "wifip2p";
当执行dumpsys wifip2p的时候，并没有任何输出，为什么呢？我们看看WifiP2pService的代码
@Override
protected void dump(FileDescriptor fd, PrintWriter pw, String[] args) {
if (mContext.checkCallingOrSelfPermission(android.Manifest.permission.DUMP)
!= PackageManager.PERMISSION_GRANTED) {
pw.println("Permission Denial: can't dump WifiP2pService from from pid="
+ Binder.getCallingPid()
+ ", uid=" + Binder.getCallingUid());
return;
}
}
现在似乎可以理解为什么dumpsys wifip2p的时候没有输出了
我们再来看一个简单的例子
# dumpsys diskstats
Latency: 5ms [512B Data Write]
Data-Free: 362888K / 1161104K total = 31% free
Cache-Free: 116756K / 120900K total = 96% free
System-Free: 133036K / 806284K total = 16% free
ServiceManager.addService("diskstats", new DiskStatsService(context));
protected void dump(FileDescriptor fd, PrintWriter pw, String[] args) {
……
reportFreeSpace(Environment.getDataDirectory(), "Data", pw);
reportFreeSpace(Environment.getDownloadCacheDirectory(), "Cache", pw);
reportFreeSpace(new File("/system"), "System", pw);
}
private void reportFreeSpace(File path, String name, PrintWriter pw) {
try {
StatFs statfs = new StatFs(path.getPath());
long bsize = statfs.getBlockSize();
long avail = statfs.getAvailableBlocks();
long total = statfs.getBlockCount();
if (bsize <= 0 || total <= 0) {
throw new IllegalArgumentException(
"Invalid stat: bsize=" + bsize + " avail=" + avail + " total=" + total);
}
pw.print(name);
pw.print("-Free: ");
pw.print(avail * bsize / 1024);
pw.print("K / ");
pw.print(total * bsize / 1024);
pw.print("K total = ");
pw.print(avail * 100 / total);
pw.println("% free");
} catch (IllegalArgumentException e) {
pw.print(name);
pw.print("-Error: ");
pw.println(e.toString());
return;
}
}
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