使用工具查看服务信息

dumpsys工具使用

我们知道Android使用ServiceManager服务进程来管理系统所有的服务，在系统启动时，每个服务必须注册到ServiceManager进程中，那如何查看系统运行了那些服务呢？ServiceManager提供了listServices接口来罗列出系统注册的所有服务。Android提供了dumpsys工具来dump出所有的服务信息，通过以下命令可以查看系统注册的所有服务：

adb shell dumpsys  

Currently running services:
  SurfaceFlinger
  country_detector
  cpuinfo
  dbinfo
  device_policy
  devicestoragemonitor
  diskstats
  drm.drmManager
  dropbox
  entropy
  fm
  gfxinfo
  hardware
  input
  isms
  location
  lock_settings
  meminfo
  network_management
  notification
  package
  permission
  phone
  power
  samplingprofiler
  scheduling_policy
  search
  sensorservice
  serial
  servicediscovery
  sim_manager
  simphonebook
  ...
-------------------------------------------------------------------------------
DUMP OF SERVICE SurfaceFlinger:
Visible layers (count = 4)

...

也可以dump指定服务信息：

adb shell dumpsys SurfaceFlinger  

Visible layers (count = 4)
+ Layer 0x41ba5008 (com.android.settings/com.android.settings.SprdUsbSettings)
  Region transparentRegion (this=0x41ba51e4, count=0)
  Region transparentRegionScreen (this=0x41ba503c, count=0)
  Region visibleRegionScreen (this=0x41ba5018, count=0)
      z=    21005, pos=(0,0), size=( 480, 854), crop=(   0,  38, 480, 854), isOp
aque=1, needsDithering=0, invalidate=0, alpha=0x00, flags=0x00000001, tr=[1.00,
0.00][0.00, 1.00]
      client=0x41c14ee0, identity=7
      format= 2, activeBuffer=[ 480x 854: 480,  2], transform-hint=0x00, queued-
frames=0, mRefreshPending=0

...

dumpsys源码分析

dumpsys工具比较简单，就是调用ServiceManager服务的listServices来查询系统注册的所有服务，并且通过checkService接口来获取服务的Binder远程代理对象，使用每个服务的dump函数来打印该服务的相关信息。

frameworks\native\cmds\dumpsys\dumpsys.cpp

{
    signal(SIGPIPE, SIG_IGN);
    //取得ServiceManager服务的远程Binder代理对象
    sp<IServiceManager> sm = defaultServiceManager();
    fflush(stdout);
    if (sm == NULL) {
        ALOGE("Unable to get default service manager!");
        aerr << "dumpsys: Unable to get default service manager!" << endl;
        return 20;
    }
    Vector<String16> services;
    Vector<String16> args;
    //如果命令行参数只有1个
    if (argc == 1) {
            //使用ServiceManager服务的Binder远程代理对象查询所有的服务
        services = sm->listServices();
        services.sort(sort_func);
        args.add(String16("-a"));
    } else {
            //添加命令行指定的服务及参数
        services.add(String16(argv[1]));
        for (int i=2; i<argc; i++) {
            args.add(String16(argv[i]));
        }
    }
    //根据服务名称查找服务对应的Binder代理对象，如果存在，打印该服务
    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;
            }
        }
    }
    //调用服务的dump函数打印服务相关信息
    for (size_t i=0; i<N; i++) {
        sp<IBinder> service = sm->checkService(services[i]);
        if (service != NULL) {
            if (N > 1) {
                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;
        }
    }
    return 0;
}

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