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
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