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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