来源:https://www.jianshu.com/p/528303e3afba

一. 概述

在调试分析Android的过程中，比较常用的地查看EventLog，非常简洁明了地展现当前Activity各种状态，当然不至于此，比如还有window的信息。那么本文就列举以下am相关的tags含义。

本文涉及的源码类有EventLog.java, EventLogTags.java，另外tags格式的定义位于文件/system/etc/event-log-tags。

如果在终端输入：

logcat -b events

那么会输出大量类似这样的信息：

06-01 13:44:55.518  7361  8289 I am_create_service: [0,111484394,.StatService,10094,7769]
06-01 13:44:55.540  7361  8343 I am_proc_bound: [0,3976,com.android.providers.calendar]
06-01 13:44:55.599  7361  8033 I am_create_service: [0,61349752,.UpdateService,10034,1351]
06-01 13:44:55.625  7361  7774 I am_destroy_service: [0,61349752,1351]
...

通过字面意思，就能得到不少信息量，比如am_create_service，创建service，但是后面括号中内容的具体含义，其实有很高的价值。 接下来通过一张表格来展示含义。

二. EventLog

2.1 ActivityManager

Num	TagName	格式	功能
30001	am_finish_activity	User,Token,TaskID,ComponentName,Reason
30002	am_task_to_front	User,Task
30003	am_new_intent	User,Token,TaskID,ComponentName,Action,MIMEType,URI,Flags
30004	am_create_task	User ,Task ID
30005	am_create_activity	User ,Token ,TaskID ,ComponentName,Action,MIMEType,URI,Flags
30006	am_restart_activity	User ,Token ,TaskID,ComponentName
30007	am_resume_activity	User ,Token ,TaskID,ComponentName
30008	am_anr	User ,pid ,Package Name,Flags ,reason	ANR
30009	am_activity_launch_time	User ,Token ,ComponentName,time
30010	am_proc_bound	User ,PID ,ProcessName
30011	am_proc_died	User ,PID ,ProcessName
30012	am_failed_to_pause	User ,Token ,Wanting to pause,Currently pausing
30013	am_pause_activity	User ,Token ,ComponentName
30014	am_proc_start	User ,PID ,UID ,ProcessName,Type,Component
30015	am_proc_bad	User ,UID ,ProcessName
30016	am_proc_good	User ,UID ,ProcessName
30017	am_low_memory	NumProcesses	Lru
30018	am_destroy_activity	User ,Token ,TaskID,ComponentName,Reason
30019	am_relaunch_resume_activity	User ,Token ,TaskID,ComponentName
30020	am_relaunch_activity	User ,Token ,TaskID,ComponentName
30021	am_on_paused_called	User ,ComponentName
30022	am_on_resume_called	User ,ComponentName
30023	am_kill	User ,PID ,ProcessName,OomAdj ,Reason	杀进程
30024	am_broadcast_discard_filter	User ,Broadcast ,Action,ReceiverNumber,BroadcastFilter
30025	am_broadcast_discard_app	User ,Broadcast ,Action,ReceiverNumber,App
30030	am_create_service	User ,ServiceRecord ,Name,UID ,PID
30031	am_destroy_service	User ,ServiceRecord ,PID
30032	am_process_crashed_too_much	User ,Name,PID
30033	am_drop_process	PID
30034	am_service_crashed_too_much	User ,Crash Count,ComponentName,PID
30035	am_schedule_service_restart	User ,ComponentName,Time
30036	am_provider_lost_process	User ,Package Name,UID ,Name
30037	am_process_start_timeout	User ,PID ,UID ,ProcessName	timeout
30039	am_crash	User ,PID ,ProcessName,Flags ,Exception,Message,File,Line	Crash
30040	am_wtf	User ,PID ,ProcessName,Flags ,Tag,Message	Wtf
30041	am_switch_user	id
30042	am_activity_fully_drawn_time	User ,Token ,ComponentName,time
30043	am_focused_activity	User ,ComponentName
30044	am_home_stack_moved	User ,To Front ,Top Stack Id ,Focused Stack Id ,Reason
30045	am_pre_boot	User ,Package
30046	am_meminfo	Cached,Free,Zram,Kernel,Native	内存
30047	am_pss	Pid, UID, ProcessName, Pss, Uss	进程

下面列举tag可能使用的部分场景：

• am_low_memory：位于AMS.killAllBackgroundProcesses或者AMS.appDiedLocked，记录当前Lru进程队列长度。
• am_pss：位于AMS.recordPssSampleLocked(
• am_meminfo：位于AMS.dumpApplicationMemoryUsage
• am_proc_start:位于AMS.startProcessLocked，启动进程
• am_proc_bound:位于AMS.attachApplicationLocked
• am_kill: 位于ProcessRecord.kill，杀掉进程
• am_anr: 位于AMS.appNotResponding
• am_crash:位于AMS.handleApplicationCrashInner
• am_wtf:位于AMS.handleApplicationWtf
• am_activity_launch_time：位于ActivityRecord.reportLaunchTimeLocked()，后面两个参数分别是thisTime和 totalTime.
• am_activity_fully_drawn_time:位于ActivityRecord.reportFullyDrawnLocked, 后面两个参数分别是thisTime和 totalTime
• am_broadcast_discard_filter:位于BroadcastQueue.logBroadcastReceiverDiscardLocked
• am_broadcast_discard_app:位于BroadcastQueue.logBroadcastReceiverDiscardLocked

Activity生命周期相关的方法:

• am_on_resume_called: 位于AT.performResumeActivity
• am_on_paused_called: 位于AT.performPauseActivity, performDestroyActivity
• am_resume_activity: 位于AS.resumeTopActivityInnerLocked
• am_pause_activity: 位于AS.startPausingLocked
• am_finish_activity: 位于AS.finishActivityLocked, removeHistoryRecordsForAppLocked
• am_destroy_activity: 位于AS.destroyActivityLocked
• am_focused_activity: 位于AMS.setFocusedActivityLocked, clearFocusedActivity
• am_restart_activity: 位于ASS.realStartActivityLocked
• am_create_activity: 位于ASS.startActivityUncheckedLocked
• am_new_intent: 位于ASS.startActivityUncheckedLocked
• am_task_to_front: 位于AS.moveTaskToFrontLocked

Window相关

• wm_task_moved: 位于TaskStack.positionTask()
  • TaskId, toTop ? 1 : 0, position；
  • 206，1，3，是指吧TaskId=206的移动到栈顶(即该栈的长度为4)
• am_home_stack_moved: 位于ASS.moveHomeStack
  • CurrentUser, toFront ? 1:0 , homStackId, FocusedStackId
  • 0,1,0,0, 是指userId=0, home栈顶的StackId=0, 当前focusedStackId=0,

2.2 Power

Num	TagName	格式	功能
2722	battery_level	level, voltage, temperature
2723	battery_status	status,health,present,plugged,technology
2730	battery_discharge	duration, minLevel,maxLevel
2724	power_sleep_requested	wakeLocksCleared	唤醒锁数量
2725	power_screen_broadcast_send	wakelockCount
2726	power_screen_broadcast_done	on, broadcastDuration, wakelockCount
2727	power_screen_broadcast_stop	which,wakelockCount	系统还没进入ready状态
2728	power_screen_state	offOrOn, becauseOfUser, totalTouchDownTime, touchCycles
2729	power_partial_wake_state	releasedorAcquired, tag

部分含义：

• battery_level: [19,3660,352] //剩余电量19%, 电池电压3.66v, 电池温度35.2℃
• power_screen_state: [0,3,0,0] // 灭屏状态(0), 屏幕超时(3). 当然还有其他设备管理策略(1),其他理由都为用户行为(2)
• power_screen_state: [1,0,0,0] // 亮屏状态(1)

下面列举tag可能使用的部分场景：

• power_sleep_requested: 位于PMS.goToSleepNoUpdateLocked
• power_screen_state:位于Notifer.handleEarlyInteractiveChange, handleLateInteractiveChange

三. EventLog完整语义分析

在源码EventLogTags.java中,有大量类似的定义,那么括号中数字是什么含义呢? (以进程启动为例)

30014 am_proc_start (User|1|5),(PID|1|5),(UID|1|5),(Process Name|3),(Type|3),(Component|3)

am_proc_start之后紧跟着的几个括号，其中括号里的内容格式如下：

(<name>|data type[|data unit])
(<名字>|数据类型[|数据单位])

那么(User|1|5) ==> 名字为User, 数据类型为1，数据单位为5，下面再来看看数据类型和数据单位：

3.1 数据类型

• 1: int
• 2: long
• 3: string
• 4: list

数据类型中int和string用得最多.

3.2 数据单位

• 1: Number of objects(对象个数)
• 2: Number of bytes(字节数)
• 3: Number of milliseconds(毫秒)
• 4: Number of allocations(分配个数)
• 5: Id
• 6: Percent(百分比)

3.3 实例解析

有了前面的准备知识，再来完整的看看如下语句：

am_proc_start (User|1|5),(PID|1|5),(UID|1|5),(Process Name|3),(Type|3),(Component|3) am_proc_start: [0,9227,10002,com.android.browser,content provider,com.android.browser/.provider.BrowserProvider2] 

含义如下：

进程启动: UserId=0, pid=9227, uid=10002, ProcessName=com.android.browser, 数据类型=ContentProvider, 组件=com.android.browser/.provider.BrowserProvider2