源码基于：Android R
接上一篇：Android oom_adj 更新原理(一)
12. computeOomAdjLocked()
frameworks/base/services/core/java/com/android/server/am/OomAdjuster.java
private final boolean computeOomAdjLocked(ProcessRecord app, int cachedAdj,
ProcessRecord topApp, boolean doingAll, long now, boolean cycleReEval,
boolean computeClients) {
// 每次updateOomAdjLocked() 调用都会有个 mAdjSeq序号，用以确认该进程是否已经处理
if (mAdjSeq == app.adjSeq) {
if (app.adjSeq == app.completedAdjSeq) { //是否已经完成
// This adjustment has already been computed successfully.
return false;
} else { //如果没有完成，将进程 containsCycle置true
// The process is being computed, so there is a cycle. We cannot
// rely on this process's state.
app.containsCycle = true;
return false;
}
}
// 进程的thread不存在，应该是个empty，初始化之后放回，adj 被设为CACHED_APP_MAX_ADJ
if (app.thread == null) {
app.adjSeq = mAdjSeq;
app.setCurrentSchedulingGroup(ProcessList.SCHED_GROUP_BACKGROUND);
app.setCurProcState(PROCESS_STATE_CACHED_EMPTY);
app.curAdj = ProcessList.CACHED_APP_MAX_ADJ;
app.setCurRawAdj(ProcessList.CACHED_APP_MAX_ADJ);
app.completedAdjSeq = app.adjSeq;
app.curCapability = PROCESS_CAPABILITY_NONE;
return false;
}
// 如果不是 empty进程，进一步处理，相关的属性初始化
app.adjTypeCode = ActivityManager.RunningAppProcessInfo.REASON_UNKNOWN;
app.adjSource = null;
app.adjTarget = null;
app.empty = false;
app.setCached(false);
app.shouldNotFreeze = false;
final int appUid = app.info.uid;
final int logUid = mService.mCurOomAdjUid;
// 存放app 的当前adj，后面curAdj会变动
int prevAppAdj = app.curAdj;
int prevProcState = app.getCurProcState();
int prevCapability = app.curCapability;
// max adj 在0 以下的进程都是重要的系统进程(maxAdj初始化都为1001)，
// 这里的FOREGROUND_APP_ADJ = 0
if (app.maxAdj <= ProcessList.FOREGROUND_APP_ADJ) {
...
app.adjType = "fixed";
app.adjSeq = mAdjSeq;
app.setCurRawAdj(app.maxAdj);
app.setHasForegroundActivities(false);
app.setCurrentSchedulingGroup(ProcessList.SCHED_GROUP_DEFAULT);
app.curCapability = PROCESS_CAPABILITY_ALL;
app.setCurProcState(ActivityManager.PROCESS_STATE_PERSISTENT);
// System processes can do UI, and when they do we want to have
// them trim their memory after the user leaves the UI. To
// facilitate this, here we need to determine whether or not it
// is currently showing UI.
//系统进程是可以显示UI 的，当离开UI之后系统想trim内存
// 这里确定是否正在显示UI，默认值为true，即不显示UI
app.systemNoUi = true;
if (app == topApp) { //如果进程就是topApp，那设置为false，正在显示UI
app.systemNoUi = false;
app.setCurrentSchedulingGroup(ProcessList.SCHED_GROUP_TOP_APP);
app.adjType = "pers-top-activity";
} else if (app.hasTopUi()) { //另外进程有处理TOP UI，该值也设为false
// sched group/proc state adjustment is below
app.systemNoUi = false;
app.adjType = "pers-top-ui";
} else if (app.getCachedHasVisibleActivities()) {
app.systemNoUi = false;
}
// 如果该系统进程正在显示UI，调整proc_state
if (!app.systemNoUi) {
if (mService.mWakefulness == PowerManagerInternal.WAKEFULNESS_AWAKE) {
// 亮屏，提升proc_state至PERSISTENT_UI
app.setCurProcState(ActivityManager.PROCESS_STATE_PERSISTENT_UI);
app.setCurrentSchedulingGroup(ProcessList.SCHED_GROUP_TOP_APP);
} else {
// 屏灭，控制UI schedule
app.setCurProcState(PROCESS_STATE_BOUND_FOREGROUND_SERVICE);
app.setCurrentSchedulingGroup(ProcessList.SCHED_GROUP_RESTRICTED);
}
}
// 设置当前 unlimit proc_state
app.setCurRawProcState(app.getCurProcState());
// adj 提升到最大，重要性下降
app.curAdj = app.maxAdj;
// 完成处理，将completedAdjSeq设置为当前进程 adjSeq
app.completedAdjSeq = app.adjSeq;
// if curAdj is less than prevAppAdj, then this process was promoted
return app.curAdj < prevAppAdj || app.getCurProcState() < prevProcState;
}
// 对于maxAdj > 0 (即大于FOREGROUND_APP_ADJ)的进程继续下面的流程，
// 默认将systemNoUi该值设为false
app.systemNoUi = false;
// 该变量用以获取系统top进程的 proc_state
// 该变量只有两个值：PROCESS_STATE_TOP 和 PROCESS_STATE_TOP_SLEEPING
final int PROCESS_STATE_CUR_TOP = mService.mAtmInternal.getTopProcessState();
// Determine the importance of the process, starting with most
// important to least, and assign an appropriate OOM adjustment.
int adj;
int schedGroup;
int procState;
int cachedAdjSeq;
int capability = 0;
boolean foregroundActivities = false;
// 根据不同场景设置前台进程的 adjType，并且更新adj、schedGroup、procState
if (PROCESS_STATE_CUR_TOP == PROCESS_STATE_TOP && app == topApp) { //前台进程
// The last app on the list is the foreground app.
adj = ProcessList.FOREGROUND_APP_ADJ;
schedGroup = ProcessList.SCHED_GROUP_TOP_APP;
app.adjType = "top-activity";
foregroundActivities = true;
procState = PROCESS_STATE_CUR_TOP;
if (DEBUG_OOM_ADJ_REASON || logUid == appUid) {
reportOomAdjMessageLocked(TAG_OOM_ADJ, "Making top: " + app);
}
} else if (app.runningRemoteAnimation) { //正在运行远程动画
adj = ProcessList.VISIBLE_APP_ADJ;
schedGroup = ProcessList.SCHED_GROUP_TOP_APP;
app.adjType = "running-remote-anim";
procState = PROCESS_STATE_CUR_TOP;
...
} else if (app.getActiveInstrumentation() != null) { //与测试相关的场景
// Don't want to kill running instrumentation.
adj = ProcessList.FOREGROUND_APP_ADJ;
schedGroup = ProcessList.SCHED_GROUP_DEFAULT;
app.adjType = "instrumentation";
procState = PROCESS_STATE_FOREGROUND_SERVICE;
if (DEBUG_OOM_ADJ_REASON || logUid == appUid) {
reportOomAdjMessageLocked(TAG_OOM_ADJ, "Making instrumentation: " + app);
}
} else if (app.getCachedIsReceivingBroadcast(mTmpBroadcastQueue)) { //cache是否在接受广播
//处于接受广播状态的进程站在OOM killer的目的，也被认为是前台进程
adj = ProcessList.FOREGROUND_APP_ADJ;
schedGroup = (mTmpBroadcastQueue.contains(mService.mFgBroadcastQueue))
? ProcessList.SCHED_GROUP_DEFAULT : ProcessList.SCHED_GROUP_BACKGROUND;
app.adjType = "broadcast";
procState = ActivityManager.PROCESS_STATE_RECEIVER;
if (DEBUG_OOM_ADJ_REASON || logUid == appUid) {
reportOomAdjMessageLocked(TAG_OOM_ADJ, "Making broadcast: " + app);
}
} else if (app.executingServices.size() > 0) { //正在运行service调用，也看作前台进程
// An app that is currently executing a service callback also
// counts as being in the foreground.
adj = ProcessList.FOREGROUND_APP_ADJ;
schedGroup = app.execServicesFg ?
ProcessList.SCHED_GROUP_DEFAULT : ProcessList.SCHED_GROUP_BACKGROUND;
app.adjType = "exec-service";
procState = PROCESS_STATE_SERVICE;
if (DEBUG_OOM_ADJ_REASON || logUid == appUid) {
reportOomAdjMessageLocked(TAG_OOM_ADJ, "Making exec-service: " + app);
}
//Slog.i(TAG, "EXEC " + (app.execServicesFg ? "FG" : "BG") + ": " + app);
} else if (app == topApp) { //topApp，此时PROCESS_STATE_CUR_TOP 处于SLEEPING
adj = ProcessList.FOREGROUND_APP_ADJ;
schedGroup = ProcessList.SCHED_GROUP_BACKGROUND;
app.adjType = "top-sleeping";
foregroundActivities = true;
procState = PROCESS_STATE_CUR_TOP;
if (DEBUG_OOM_ADJ_REASON || logUid == appUid) {
reportOomAdjMessageLocked(TAG_OOM_ADJ, "Making top (sleeping): " + app);
}
} else { //empty进程
// As far as we know the process is empty. We may change our mind later.
schedGroup = ProcessList.SCHED_GROUP_BACKGROUND;
// At this point we don't actually know the adjustment. Use the cached adj
// value that the caller wants us to.
adj = cachedAdj;
procState = PROCESS_STATE_CACHED_EMPTY;
if (!app.containsCycle) {
app.setCached(true);
app.empty = true;
app.adjType = "cch-empty";
}
if (DEBUG_OOM_ADJ_REASON || logUid == appUid) {
reportOomAdjMessageLocked(TAG_OOM_ADJ, "Making empty: " + app);
}
}
// foregroundActivities 这个变量记录是否已经是前台进程(app为topapp时为true)
// 如果不是前台进程，且存在cache activities，则需要继续确定adj，重置adj 为cache
if (!foregroundActivities && app.getCachedHasActivities()) {
// mTmpComputeOomAdjWindowCallback计算adj时的window回调
// computeOomAdjFromActivitiesIfNecessary判断是否执行过
// 如果未执行过，则调用callback.initialize把adj/prostate存储
// 然后判断是否visible（adj=VISIBLE_APP_ADJ）、
// paused/stop(adj=PERCEPTIBLE_APP_ADJ)、other(procState=PROCESS_STATE_CACHED_ACTIVITY)
// 然后把adj/prostate赋值给app.mCachedAdj/app.mCachedProcState
// 如果执行过，则上一次计算出来的值
app.computeOomAdjFromActivitiesIfNecessary(mTmpComputeOomAdjWindowCallback,
adj, foregroundActivities, procState, schedGroup, appUid, logUid,
PROCESS_STATE_CUR_TOP);
// // 如果进入cache的应用，这里adj会为1001,procstate为PROCESS_STATE_CACHED_ACTIVITY
adj = app.mCachedAdj;
foregroundActivities = app.mCachedForegroundActivities;
procState = app.mCachedProcState;
schedGroup = app.mCachedSchedGroup;
}
//带有recentTasks的cache；如果adj过大，回拉
if (procState > PROCESS_STATE_CACHED_RECENT && app.getCachedHasRecentTasks()) {
procState = PROCESS_STATE_CACHED_RECENT;
app.adjType = "cch-rec";
if (DEBUG_OOM_ADJ_REASON || logUid == appUid) {
reportOomAdjMessageLocked(TAG_OOM_ADJ, "Raise procstate to cached recent: " + app);
}
}
//重要性低于可感知进程且级别高于带前台service的处理
//对于adj大于可感知进程，级别大于带service的前台进程，分带service和overlay UI分别处理，
//adj都是perceptible，但级别不同
if (adj > ProcessList.PERCEPTIBLE_APP_ADJ
|| procState > PROCESS_STATE_FOREGROUND_SERVICE) {
if (app.hasForegroundServices()) { //带前台service
// The user is aware of this app, so make it visible.
adj = ProcessList.PERCEPTIBLE_APP_ADJ; //adj任然设为PERCEPTIBLE_APP_ADJ
procState = PROCESS_STATE_FOREGROUND_SERVICE; //procState不同
app.adjType = "fg-service";
app.setCached(false);
schedGroup = ProcessList.SCHED_GROUP_DEFAULT;
...
} else if (app.hasOverlayUi()) { //overlay UI
// The process is display an overlay UI.
adj = ProcessList.PERCEPTIBLE_APP_ADJ;
procState = PROCESS_STATE_IMPORTANT_FOREGROUND;
app.setCached(false);
app.adjType = "has-overlay-ui";
schedGroup = ProcessList.SCHED_GROUP_DEFAULT;
...
}
}
// 从前台进程切换到带前台service，允许保持15s的更高级别adj，保证其完成一些剩余操作
if (app.hasForegroundServices() && adj > ProcessList.PERCEPTIBLE_RECENT_FOREGROUND_APP_ADJ
&& (app.lastTopTime + mConstants.TOP_TO_FGS_GRACE_DURATION > now
|| app.setProcState <= PROCESS_STATE_TOP)) {
adj = ProcessList.PERCEPTIBLE_RECENT_FOREGROUND_APP_ADJ; //adj被设为了50
app.adjType = "fg-service-act";
...
}
//adj大于可感知进程，级别大于后台进程
if (adj > ProcessList.PERCEPTIBLE_APP_ADJ
|| procState > PROCESS_STATE_TRANSIENT_BACKGROUND) {
if (app.forcingToImportant != null) { //使进程变成更重要的标志
adj = ProcessList.PERCEPTIBLE_APP_ADJ;
//级别降到PROCESS_STATE_TRANSIENT_BACKGROUND
procState = PROCESS_STATE_TRANSIENT_BACKGROUND;
app.setCached(false);
app.adjType = "force-imp";
app.adjSource = app.forcingToImportant;
schedGroup = ProcessList.SCHED_GROUP_DEFAULT;
if (DEBUG_OOM_ADJ_REASON || logUid == appUid) {
reportOomAdjMessageLocked(TAG_OOM_ADJ, "Raise to force imp: " + app);
}
}
}
//重量级后台进程，把adj和proc_state都拉回到 heavy weight水平
if (app.getCachedIsHeavyWeight()) {
if (adj > ProcessList.HEAVY_WEIGHT_APP_ADJ) {
// We don't want to kill the current heavy-weight process.
adj = ProcessList.HEAVY_WEIGHT_APP_ADJ;
schedGroup = ProcessList.SCHED_GROUP_BACKGROUND;
app.setCached(false);
app.adjType = "heavy";
if (DEBUG_OOM_ADJ_REASON || logUid == appUid) {
reportOomAdjMessageLocked(TAG_OOM_ADJ, "Raise adj to heavy: " + app);
}
}
if (procState > ActivityManager.PROCESS_STATE_HEAVY_WEIGHT) {
procState = ActivityManager.PROCESS_STATE_HEAVY_WEIGHT;
app.adjType = "heavy";
if (DEBUG_OOM_ADJ_REASON || logUid == appUid) {
reportOomAdjMessageLocked(TAG_OOM_ADJ, "Raise procstate to heavy: " + app);
}
}
}
//HOME 进程，将其拉回HOME_APP_ADJ
if (app.getCachedIsHomeProcess()) {
if (adj > ProcessList.HOME_APP_ADJ) {
// This process is hosting what we currently consider to be the
// home app, so we don't want to let it go into the background.
adj = ProcessList.HOME_APP_ADJ;
schedGroup = ProcessList.SCHED_GROUP_BACKGROUND;
app.setCached(false);
app.adjType = "home";
if (DEBUG_OOM_ADJ_REASON || logUid == appUid) {
reportOomAdjMessageLocked(TAG_OOM_ADJ, "Raise adj to home: " + app);
}
}
if (procState > ActivityManager.PROCESS_STATE_HOME) {
procState = ActivityManager.PROCESS_STATE_HOME;
app.adjType = "home";
if (DEBUG_OOM_ADJ_REASON || logUid == appUid) {
reportOomAdjMessageLocked(TAG_OOM_ADJ, "Raise procstate to home: " + app);
}
}
}
//前一个进程仍然带有activity，或者20s内刚被使用的provider进程，设置为PREVIOUS_APP_ADJ
if (app.getCachedIsPreviousProcess() && app.getCachedHasActivities()) {
if (adj > ProcessList.PREVIOUS_APP_ADJ) {
// This was the previous process that showed UI to the user.
// We want to try to keep it around more aggressively, to give
// a good experience around switching between two apps.
adj = ProcessList.PREVIOUS_APP_ADJ;
schedGroup = ProcessList.SCHED_GROUP_BACKGROUND;
app.setCached(false);
app.adjType = "previous";
if (DEBUG_OOM_ADJ_REASON || logUid == appUid) {
reportOomAdjMessageLocked(TAG_OOM_ADJ, "Raise adj to prev: " + app);
}
}
if (procState > PROCESS_STATE_LAST_ACTIVITY) {
procState = PROCESS_STATE_LAST_ACTIVITY;
app.adjType = "previous";
if (DEBUG_OOM_ADJ_REASON || logUid == appUid) {
reportOomAdjMessageLocked(TAG_OOM_ADJ, "Raise procstate to prev: " + app);
}
}
}
//前期进程的处理情况，这里可以做个打印
if (false) Slog.i(TAG, "OOM " + app + ": initial adj=" + adj
+ " reason=" + app.adjType);
// 当进程有关联的services或providers，还需要根据services和providers继续更新adj
if (cycleReEval) {
procState = Math.min(procState, app.getCurRawProcState());
adj = Math.min(adj, app.getCurRawAdj());
schedGroup = Math.max(schedGroup, app.getCurrentSchedulingGroup());
}
//前面根据不同场景更新了adj，schedGroup，proc_state等，先暂时更新到processRecord app的参数里面
app.setCurRawAdj(adj);
app.setCurRawProcState(procState);
app.hasStartedServices = false;
app.adjSeq = mAdjSeq;
//处理service中备份的进程
final BackupRecord backupTarget = mService.mBackupTargets.get(app.userId);
if (backupTarget != null && app == backupTarget.app) {
// If possible we want to avoid killing apps while they're being backed up
if (adj > ProcessList.BACKUP_APP_ADJ) {
if (DEBUG_BACKUP) Slog.v(TAG_BACKUP, "oom BACKUP_APP_ADJ for " + app);
adj = ProcessList.BACKUP_APP_ADJ;
if (procState > PROCESS_STATE_TRANSIENT_BACKGROUND) {
procState = PROCESS_STATE_TRANSIENT_BACKGROUND;
}
app.adjType = "backup";
if (DEBUG_OOM_ADJ_REASON || logUid == appUid) {
reportOomAdjMessageLocked(TAG_OOM_ADJ, "Raise adj to backup: " + app);
}
app.setCached(false);
}
if (procState > ActivityManager.PROCESS_STATE_BACKUP) {
procState = ActivityManager.PROCESS_STATE_BACKUP;
app.adjType = "backup";
if (DEBUG_OOM_ADJ_REASON || logUid == appUid) {
reportOomAdjMessageLocked(TAG_OOM_ADJ, "Raise procstate to backup: " + app);
}
}
}
int capabilityFromFGS = 0; // capability from foreground service.
/**************以下为service连接相关的处理逻辑***************/
//遍历adj > 前台进程的进程中正在运行的service，根据这些service进一步更新当前app的adj
for (int is = app.numberOfRunningServices() - 1;
is >= 0 && (adj > ProcessList.FOREGROUND_APP_ADJ
|| schedGroup == ProcessList.SCHED_GROUP_BACKGROUND
|| procState > PROCESS_STATE_TOP);
is--) {
ServiceRecord s = app.getRunningServiceAt(is);
if (s.startRequested) {
// 如果服务启动，则处理procState最低为PROCESS_STATE_SERVICE
app.hasStartedServices = true;
if (procState > PROCESS_STATE_SERVICE) {
procState = PROCESS_STATE_SERVICE;
app.adjType = "started-services";
if (DEBUG_OOM_ADJ_REASON || logUid == appUid) {
reportOomAdjMessageLocked(TAG_OOM_ADJ,
"Raise procstate to started service: " + app);
}
}
//有显示的UI并且不是home，则标记cch-started-ui-services
if (!s.mKeepWarming && app.hasShownUi && !app.getCachedIsHomeProcess()) {
// If this process has shown some UI, let it immediately
// go to the LRU list because it may be pretty heavy with
// UI stuff. We'll tag it with a label just to help
// debug and understand what is going on.
if (adj > ProcessList.SERVICE_ADJ) {
app.adjType = "cch-started-ui-services";
}
} else {
// 如果上一次调用service的时间间隔超过30 min，则设置adj为SERVICE_ADJ
if (s.mKeepWarming
|| now < (s.lastActivity + mConstants.MAX_SERVICE_INACTIVITY)) {
// This service has seen some activity within
// recent memory, so we will keep its process ahead
// of the background processes.
if (adj > ProcessList.SERVICE_ADJ) {
adj = ProcessList.SERVICE_ADJ;
app.adjType = "started-services";
if (DEBUG_OOM_ADJ_REASON || logUid == appUid) {
reportOomAdjMessageLocked(TAG_OOM_ADJ,
"Raise adj to started service: " + app);
}
app.setCached(false);
}
}
// If we have let the service slide into the background
// state, still have some text describing what it is doing
// even though the service no longer has an impact.
if (adj > ProcessList.SERVICE_ADJ) {
app.adjType = "cch-started-services";
}
}
}
//service运行在前台，主要更新capabilityFromFGS
if (s.isForeground) {
final int fgsType = s.foregroundServiceType;
if (s.mAllowWhileInUsePermissionInFgs) {
capabilityFromFGS |=
(fgsType & FOREGROUND_SERVICE_TYPE_LOCATION)
!= 0 ? PROCESS_CAPABILITY_FOREGROUND_LOCATION : 0;
boolean enabled = false;
try {
enabled = mPlatformCompat.isChangeEnabled(
CAMERA_MICROPHONE_CAPABILITY_CHANGE_ID, s.appInfo);
} catch (RemoteException e) {
}
if (enabled) {
capabilityFromFGS |=
(fgsType & FOREGROUND_SERVICE_TYPE_CAMERA)
!= 0 ? PROCESS_CAPABILITY_FOREGROUND_CAMERA : 0;
capabilityFromFGS |=
(fgsType & FOREGROUND_SERVICE_TYPE_MICROPHONE)
!= 0 ? PROCESS_CAPABILITY_FOREGROUND_MICROPHONE : 0;
} else {
capabilityFromFGS |= PROCESS_CAPABILITY_FOREGROUND_CAMERA
| PROCESS_CAPABILITY_FOREGROUND_MICROPHONE;
}
}
}
//该服务还被其他客户端连接时，遍历所有连接该service的客户端，对该服务进行adj计算
ArrayMap<IBinder, ArrayList<ConnectionRecord>> serviceConnections = s.getConnections();
for (int conni = serviceConnections.size() - 1;
conni >= 0 && (adj > ProcessList.FOREGROUND_APP_ADJ
|| schedGroup == ProcessList.SCHED_GROUP_BACKGROUND
|| procState > PROCESS_STATE_TOP);
conni--) {
// 获取这个服务链接的客户端进程
ArrayList<ConnectionRecord> clist = serviceConnections.valueAt(conni);
for (int i = 0;
i < clist.size() && (adj > ProcessList.FOREGROUND_APP_ADJ
|| schedGroup == ProcessList.SCHED_GROUP_BACKGROUND
|| procState > PROCESS_STATE_TOP);
i++) {
// XXX should compute this based on the max of
// all connected clients.
ConnectionRecord cr = clist.get(i);
if (cr.binding.client == app) { //连接到自己，不处理
// Binding to oneself is not interesting.
continue;
}
boolean trackedProcState = false;
ProcessRecord client = cr.binding.client; //获取客户端的ProcessRecord
/传入的参数，是否计算客户端的adj， 如果更新所有进程，则为true
if (computeClients) {
computeOomAdjLocked(client, cachedAdj, topApp, doingAll, now,
cycleReEval, true);
} else {
client.setCurRawAdj(client.setAdj);
client.setCurRawProcState(client.setProcState);
}
int clientAdj = client.getCurRawAdj();
int clientProcState = client.getCurRawProcState();
// 假如不包含BIND_WAIVE_PRIORITY状态，即没有加入特殊标记不影响服务进程优先级
if ((cr.flags & Context.BIND_WAIVE_PRIORITY) == 0) {
if (shouldSkipDueToCycle(app, client, procState, adj, cycleReEval)) {
continue;
}
if (cr.hasFlag(Context.BIND_INCLUDE_CAPABILITIES)) {
capability |= client.curCapability;
}
// 如果客户端进程是cache，则认为是empty进程
if (clientProcState >= PROCESS_STATE_CACHED_ACTIVITY) {
// If the other app is cached for any reason, for purposes here
// we are going to consider it empty. The specific cached state
// doesn't propagate except under certain conditions.
clientProcState = PROCESS_STATE_CACHED_EMPTY;
}
String adjType = null;
// BIND_ALLOW_OOM_MANAGEMENT代表保持服务受默认的服务管理器管理，
// 当内存不足时候，会销毁服务
if ((cr.flags&Context.BIND_ALLOW_OOM_MANAGEMENT) != 0) {
// Not doing bind OOM management, so treat
// this guy more like a started service.
if (app.hasShownUi && !app.getCachedIsHomeProcess()) {
// If this process has shown some UI, let it immediately
// go to the LRU list because it may be pretty heavy with
// UI stuff. We'll tag it with a label just to help
// debug and understand what is going on.
if (adj > clientAdj) {
adjType = "cch-bound-ui-services";
}
app.setCached(false);
clientAdj = adj;
clientProcState = procState;
} else {
if (now >= (s.lastActivity
+ mConstants.MAX_SERVICE_INACTIVITY)) {
// This service has not seen activity within
// recent memory, so allow it to drop to the
// LRU list if there is no other reason to keep
// it around. We'll also tag it with a label just
// to help debug and undertand what is going on.
if (adj > clientAdj) {
adjType = "cch-bound-services";
}
clientAdj = adj;
}
}
}
// 假如服务进程的优先级小于客户端进程，则提升优先级
if (adj > clientAdj) {
// If this process has recently shown UI, and
// the process that is binding to it is less
// important than being visible, then we don't
// care about the binding as much as we care
// about letting this process get into the LRU
// list to be killed and restarted if needed for
// memory.
// 如果当前进程有activity，但是与他关联的进程大于可感知状态
if (app.hasShownUi && !app.getCachedIsHomeProcess()
&& clientAdj > ProcessList.PERCEPTIBLE_APP_ADJ) {
if (adj >= ProcessList.CACHED_APP_MIN_ADJ) {
adjType = "cch-bound-ui-services";
}
} else {
int newAdj;
// BIND_ABOVE_CLIENT表明service比连接他的客户端更重要，
// 则客户端进程adj赋值给当前进程
// BIND_IMPORTANT 标识服务对客户端是非常重要的
if ((cr.flags&(Context.BIND_ABOVE_CLIENT
|Context.BIND_IMPORTANT)) != 0) {
// clientAdj 一般是大于PERSISTENT_SERVICE_ADJ的，
// 所以直接采用客户端adj
if (clientAdj >= ProcessList.PERSISTENT_SERVICE_ADJ) {
newAdj = clientAdj;
} else { //persistent进程
// make this service persistent
newAdj = ProcessList.PERSISTENT_SERVICE_ADJ;
schedGroup = ProcessList.SCHED_GROUP_DEFAULT;
procState = ActivityManager.PROCESS_STATE_PERSISTENT;
cr.trackProcState(procState, mAdjSeq, now);
trackedProcState = true;
}
} else if ((cr.flags & Context.BIND_NOT_PERCEPTIBLE) != 0
&& clientAdj <= ProcessList.PERCEPTIBLE_APP_ADJ
&& adj >= ProcessList.PERCEPTIBLE_LOW_APP_ADJ) {
// 不是可感知服务，但是adj优先级大于等于可感知，
// 则设置newadj为250
newAdj = ProcessList.PERCEPTIBLE_LOW_APP_ADJ;
} else if ((cr.flags&Context.BIND_NOT_VISIBLE) != 0
&& clientAdj < ProcessList.PERCEPTIBLE_APP_ADJ
&& adj >= ProcessList.PERCEPTIBLE_APP_ADJ) {
// 假如绑定服务状态BIND_NOT_VISIBLE，则设置200
newAdj = ProcessList.PERCEPTIBLE_APP_ADJ;
} else if (clientAdj >= ProcessList.PERCEPTIBLE_APP_ADJ) {
newAdj = clientAdj;
} else {
// 假如clientadj<PERCEPTIBLE_APP_ADJ，
// 则设置为VISIBLE_APP_ADJ
if (adj > ProcessList.VISIBLE_APP_ADJ) {
// TODO: Is this too limiting for apps bound from TOP?
newAdj = Math.max(clientAdj, ProcessList.VISIBLE_APP_ADJ);
} else {
newAdj = adj;
}
}
if (!client.isCached()) {
app.setCached(false);
}
if (adj > newAdj) {
adj = newAdj;
app.setCurRawAdj(adj);
adjType = "service";
}
}
}
// 根据后台情况，处理clientProcState，
// 然后赋值给当前ProcessRecord的adjSourceProcState
if ((cr.flags & (Context.BIND_NOT_FOREGROUND
| Context.BIND_IMPORTANT_BACKGROUND)) == 0) {
// This will treat important bound services identically to
// the top app, which may behave differently than generic
// foreground work.
final int curSchedGroup = client.getCurrentSchedulingGroup();
if (curSchedGroup > schedGroup) {
if ((cr.flags&Context.BIND_IMPORTANT) != 0) {
schedGroup = curSchedGroup;
} else {
schedGroup = ProcessList.SCHED_GROUP_DEFAULT;
}
}
if (clientProcState < PROCESS_STATE_TOP) {
// Special handling for above-top states (persistent
// processes). These should not bring the current process
// into the top state, since they are not on top. Instead
// give them the best bound state after that.
if (cr.hasFlag(Context.BIND_FOREGROUND_SERVICE)) {
clientProcState = PROCESS_STATE_BOUND_FOREGROUND_SERVICE; ;
} else if (mService.mWakefulness
== PowerManagerInternal.WAKEFULNESS_AWAKE
&& (cr.flags & Context.BIND_FOREGROUND_SERVICE_WHILE_AWAKE)
!= 0) {
clientProcState = PROCESS_STATE_BOUND_FOREGROUND_SERVICE;
} else {
clientProcState =
PROCESS_STATE_IMPORTANT_FOREGROUND;
}
} else if (clientProcState == PROCESS_STATE_TOP) {
// Go at most to BOUND_TOP, unless requested to elevate
// to client's state.
clientProcState = PROCESS_STATE_BOUND_TOP;
boolean enabled = false;
try {
enabled = mPlatformCompat.isChangeEnabled(
PROCESS_CAPABILITY_CHANGE_ID, client.info);
} catch (RemoteException e) {
}
if (enabled) {
if (cr.hasFlag(Context.BIND_INCLUDE_CAPABILITIES)) {
// TOP process passes all capabilities to the service.
capability |= PROCESS_CAPABILITY_ALL;
} else {
// TOP process passes no capability to the service.
}
} else {
// TOP process passes all capabilities to the service.
capability |= PROCESS_CAPABILITY_ALL;
}
}
} else if ((cr.flags & Context.BIND_IMPORTANT_BACKGROUND) == 0) {
if (clientProcState <
PROCESS_STATE_TRANSIENT_BACKGROUND) {
clientProcState =
PROCESS_STATE_TRANSIENT_BACKGROUND;
}
} else {
if (clientProcState <
PROCESS_STATE_IMPORTANT_BACKGROUND) {
clientProcState =
PROCESS_STATE_IMPORTANT_BACKGROUND;
}
}
if (schedGroup < ProcessList.SCHED_GROUP_TOP_APP
&& (cr.flags & Context.BIND_SCHEDULE_LIKE_TOP_APP) != 0) {
schedGroup = ProcessList.SCHED_GROUP_TOP_APP;
}
if (!trackedProcState) {
cr.trackProcState(clientProcState, mAdjSeq, now);
}
if (procState > clientProcState) {
procState = clientProcState;
app.setCurRawProcState(procState);
if (adjType == null) {
adjType = "service";
}
}
if (procState < PROCESS_STATE_IMPORTANT_BACKGROUND
&& (cr.flags & Context.BIND_SHOWING_UI) != 0) {
app.setPendingUiClean(true);
}
if (adjType != null) {
app.adjType = adjType;
app.adjTypeCode = ActivityManager.RunningAppProcessInfo
.REASON_SERVICE_IN_USE;
app.adjSource = cr.binding.client;
app.adjSourceProcState = clientProcState;
app.adjTarget = s.instanceName;
if (DEBUG_OOM_ADJ_REASON || logUid == appUid) {
reportOomAdjMessageLocked(TAG_OOM_ADJ, "Raise to " + adjType
+ ": " + app + ", due to " + cr.binding.client
+ " adj=" + adj + " procState="
+ ProcessList.makeProcStateString(procState));
}
}
} else { // BIND_WAIVE_PRIORITY == true
// BIND_WAIVE_PRIORITY bindings are special when it comes to the
// freezer. Processes bound via WPRI are expected to be running,
// but they are not promoted in the LRU list to keep them out of
// cached. As a result, they can freeze based on oom_adj alone.
// Normally, bindToDeath would fire when a cached app would die
// in the background, but nothing will fire when a running process
// pings a frozen process. Accordingly, any cached app that is
// bound by an unfrozen app via a WPRI binding has to remain
// unfrozen.
if (clientAdj < ProcessList.CACHED_APP_MIN_ADJ) {
app.shouldNotFreeze = true;
}
}
if ((cr.flags&Context.BIND_TREAT_LIKE_ACTIVITY) != 0) {
app.treatLikeActivity = true;
}
// 假如客户端进程的activity可见，
// 则提升当前ProcessRecord的adj为FOREGROUND_APP_ADJ
final ActivityServiceConnectionsHolder a = cr.activity;
if ((cr.flags&Context.BIND_ADJUST_WITH_ACTIVITY) != 0) {
if (a != null && adj > ProcessList.FOREGROUND_APP_ADJ
&& a.isActivityVisible()) {
adj = ProcessList.FOREGROUND_APP_ADJ;
app.setCurRawAdj(adj);
if ((cr.flags&Context.BIND_NOT_FOREGROUND) == 0) {
if ((cr.flags&Context.BIND_IMPORTANT) != 0) {
schedGroup = ProcessList.SCHED_GROUP_TOP_APP_BOUND;
} else {
schedGroup = ProcessList.SCHED_GROUP_DEFAULT;
}
}
app.setCached(false);
app.adjType = "service";
app.adjTypeCode = ActivityManager.RunningAppProcessInfo
.REASON_SERVICE_IN_USE;
app.adjSource = a;
app.adjSourceProcState = procState;
app.adjTarget = s.instanceName;
if (DEBUG_OOM_ADJ_REASON || logUid == appUid) {
reportOomAdjMessageLocked(TAG_OOM_ADJ,
"Raise to service w/activity: " + app);
}
}
}
}
}
}
/**************provider相关的处理*****************/
//根据provider客户端的状态确定当前app的 adj，scheduleGroup 和 ProcState
//遍历与当前进程相关的所有provider
for (int provi = app.pubProviders.size() - 1;
provi >= 0 && (adj > ProcessList.FOREGROUND_APP_ADJ
|| schedGroup == ProcessList.SCHED_GROUP_BACKGROUND
|| procState > PROCESS_STATE_TOP);
provi--) {
ContentProviderRecord cpr = app.pubProviders.valueAt(provi);
for (int i = cpr.connections.size() - 1;
i >= 0 && (adj > ProcessList.FOREGROUND_APP_ADJ
|| schedGroup == ProcessList.SCHED_GROUP_BACKGROUND
|| procState > PROCESS_STATE_TOP);
i--) {
ContentProviderConnection conn = cpr.connections.get(i);
ProcessRecord client = conn.client;
if (client == app) {
// Being our own client is not interesting.
continue;
}
if (computeClients) {
computeOomAdjLocked(client, cachedAdj, topApp, doingAll, now, cycleReEval,
true);
} else {
client.setCurRawAdj(client.setAdj);
client.setCurRawProcState(client.setProcState);
}
if (shouldSkipDueToCycle(app, client, procState, adj, cycleReEval)) {
continue;
}
int clientAdj = client.getCurRawAdj();
int clientProcState = client.getCurRawProcState();
if (clientProcState >= PROCESS_STATE_CACHED_ACTIVITY) {
// If the other app is cached for any reason, for purposes here
// we are going to consider it empty.
clientProcState = PROCESS_STATE_CACHED_EMPTY;
}
String adjType = null;
if (adj > clientAdj) {
if (app.hasShownUi && !app.getCachedIsHomeProcess()
&& clientAdj > ProcessList.PERCEPTIBLE_APP_ADJ) {
adjType = "cch-ui-provider";
} else {
adj = clientAdj > ProcessList.FOREGROUND_APP_ADJ
? clientAdj : ProcessList.FOREGROUND_APP_ADJ;
app.setCurRawAdj(adj);
adjType = "provider";
}
app.setCached(app.isCached() & client.isCached());
}
if (clientProcState <= PROCESS_STATE_FOREGROUND_SERVICE) {
if (adjType == null) {
adjType = "provider";
}
if (clientProcState == PROCESS_STATE_TOP) {
clientProcState = PROCESS_STATE_BOUND_TOP;
} else {
clientProcState = PROCESS_STATE_BOUND_FOREGROUND_SERVICE;
}
}
conn.trackProcState(clientProcState, mAdjSeq, now);
if (procState > clientProcState) {
procState = clientProcState;
app.setCurRawProcState(procState);
}
if (client.getCurrentSchedulingGroup() > schedGroup) {
schedGroup = ProcessList.SCHED_GROUP_DEFAULT;
}
if (adjType != null) {
app.adjType = adjType;
app.adjTypeCode = ActivityManager.RunningAppProcessInfo
.REASON_PROVIDER_IN_USE;
app.adjSource = client;
app.adjSourceProcState = clientProcState;
app.adjTarget = cpr.name;
if (DEBUG_OOM_ADJ_REASON || logUid == appUid) {
reportOomAdjMessageLocked(TAG_OOM_ADJ, "Raise to " + adjType
+ ": " + app + ", due to " + client
+ " adj=" + adj + " procState="
+ ProcessList.makeProcStateString(procState));
}
}
}
//provider有非framework层的外部进程依赖，保证其adj不高于前台进程
if (cpr.hasExternalProcessHandles()) {
if (adj > ProcessList.FOREGROUND_APP_ADJ) {
adj = ProcessList.FOREGROUND_APP_ADJ;
app.setCurRawAdj(adj);
schedGroup = ProcessList.SCHED_GROUP_DEFAULT;
app.setCached(false);
app.adjType = "ext-provider";
app.adjTarget = cpr.name;
if (DEBUG_OOM_ADJ_REASON || logUid == appUid) {
reportOomAdjMessageLocked(TAG_OOM_ADJ,
"Raise adj to external provider: " + app);
}
}
if (procState > PROCESS_STATE_IMPORTANT_FOREGROUND) {
procState = PROCESS_STATE_IMPORTANT_FOREGROUND;
app.setCurRawProcState(procState);
if (DEBUG_OOM_ADJ_REASON || logUid == appUid) {
reportOomAdjMessageLocked(TAG_OOM_ADJ,
"Raise procstate to external provider: " + app);
}
}
}
}
/**************收尾工作，有些数据需要特殊限制*****************/
//当一个进程20s前带有contentProvider，不会把他降到LRU list，避免provider进程陷入低内存状态
if (app.lastProviderTime > 0 &&
(app.lastProviderTime + mConstants.CONTENT_PROVIDER_RETAIN_TIME) > now) {
if (adj > ProcessList.PREVIOUS_APP_ADJ) {
adj = ProcessList.PREVIOUS_APP_ADJ;
schedGroup = ProcessList.SCHED_GROUP_BACKGROUND;
app.setCached(false);
app.adjType = "recent-provider";
if (DEBUG_OOM_ADJ_REASON || logUid == appUid) {
reportOomAdjMessageLocked(TAG_OOM_ADJ,
"Raise adj to recent provider: " + app);
}
}
if (procState > PROCESS_STATE_LAST_ACTIVITY) {
procState = PROCESS_STATE_LAST_ACTIVITY;
app.adjType = "recent-provider";
if (DEBUG_OOM_ADJ_REASON || logUid == appUid) {
reportOomAdjMessageLocked(TAG_OOM_ADJ,
"Raise procstate to recent provider: " + app);
}
}
}
//对cache进程进一步细分
if (procState >= PROCESS_STATE_CACHED_EMPTY) {
if (app.hasClientActivities()) {
// This is a cached process, but with client activities. Mark it so.
procState = PROCESS_STATE_CACHED_ACTIVITY_CLIENT;
app.adjType = "cch-client-act";
} else if (app.treatLikeActivity) {
// This is a cached process, but somebody wants us to treat it like it has
// an activity, okay!
procState = PROCESS_STATE_CACHED_ACTIVITY;
app.adjType = "cch-as-act";
}
}
//由adj判断是服务进程
if (adj == ProcessList.SERVICE_ADJ) {
//doingAll:传入的参数，只有一参的时候传入为true，其他二参、三参、五参都为false
// cycleReEval:传入的参数，只有一参的时候为true，其他为false
if (doingAll && !cycleReEval) {
//当A类Service个数 > service/3时，则加入到B类Service
app.serviceb = mNewNumAServiceProcs > (mNumServiceProcs/3);
mNewNumServiceProcs++;
//Slog.i(TAG, "ADJ " + app + " serviceb=" + app.serviceb);
if (!app.serviceb) { //不在service b list中
//当对于低RAM设备，则把该service直接放入B类Service
if (mService.mLastMemoryLevel > ProcessStats.ADJ_MEM_FACTOR_NORMAL
&& app.lastPss >= mProcessList.getCachedRestoreThresholdKb()) {
app.serviceHighRam = true;
app.serviceb = true;
//Slog.i(TAG, "ADJ " + app + " high ram!");
} else {
mNewNumAServiceProcs++;
//Slog.i(TAG, "ADJ " + app + " not high ram!");
}
} else { //在service b list中
app.serviceHighRam = false;
}
}
if (app.serviceb) {
adj = ProcessList.SERVICE_B_ADJ;
}
}
app.setCurRawAdj(adj);
//进一步计算之后的adj情况，可以选择打印
//Slog.i(TAG, "OOM ADJ " + app + ": pid=" + app.pid +
// " adj=" + adj + " curAdj=" + app.curAdj + " maxAdj=" + app.maxAdj);
//计算好的adj不能超过maxAdj
if (adj > app.maxAdj) {
adj = app.maxAdj;
if (app.maxAdj <= ProcessList.PERCEPTIBLE_LOW_APP_ADJ) {
schedGroup = ProcessList.SCHED_GROUP_DEFAULT;
}
}
// Put bound foreground services in a special sched group for additional
// restrictions on screen off
if (procState >= PROCESS_STATE_BOUND_FOREGROUND_SERVICE
&& mService.mWakefulness != PowerManagerInternal.WAKEFULNESS_AWAKE) {
if (schedGroup > ProcessList.SCHED_GROUP_RESTRICTED) {
schedGroup = ProcessList.SCHED_GROUP_RESTRICTED;
}
}
// apply capability from FGS.
if (app.hasForegroundServices()) {
capability |= capabilityFromFGS;
}
capability |= getDefaultCapability(app, procState);
// Do final modification to adj. Everything we do between here and applying
// the final setAdj must be done in this function, because we will also use
// it when computing the final cached adj later. Note that we don't need to
// worry about this for max adj above, since max adj will always be used to
// keep it out of the cached vaues.
app.curAdj = app.modifyRawOomAdj(adj);
app.curCapability = capability;
app.setCurrentSchedulingGroup(schedGroup);
app.setCurProcState(procState);
app.setCurRawProcState(procState);
app.setHasForegroundActivities(foregroundActivities);
app.completedAdjSeq = mAdjSeq;
// if curAdj or curProcState improved, then this process was promoted
return app.curAdj < prevAppAdj || app.getCurProcState() < prevProcState
|| app.curCapability != prevCapability ;
}一个函数快 1000 行代码，确实分析起来非常累，里面有很多逻辑，大致逻辑如下：
- 通过 mAdjSeq 确认此次计算是否有必要，是否已经计算过；
- 判断是否为空进程；
- 当maxAdj<=FOREGROUND_APP_ADJ（都是重要的系统进程）根据是否显示系统UI、是否为TOPAPP等条件设置adj、procState等，然后return；
- 前台进程相关处理，根据不同场景(远程动画、接受广播、运行service等)设置前台进程adj、adjType、procState、schedGroup；
- 如果不是前台进程，但存有cache activities，通过 computeOomAdjFromActivitiesIfNecessary()确定进程cachedadj等；
- 分别根据adj是否大于PERCEPTIBLE_APP_ADJ、HEAVY_WEIGHT_APP_ADJ、HOME_APP_ADJ、PREVIOUS_APP_ADJ等判断大致adj值，在根据activity具体运行状态进一步确认adj等值；
- 确认是否为backup进程；
- 遍历在进程上运行所有services，根据service的运行状态修正当前进程adj等值。还可能遍历引用service的所有client，进一步计算这些client 的adj值；
- 同service，遍历进程上关联的providers，根据providers以及客户端进一步修正adj值；
- 收尾，进一步确认：
- 当一个进程20s前带有contentProvider，不会把他降到LRU list，避免provider进程陷入低内存状态；
- procState >= PROCESS_STATE_CACHED_EMPTY时进一步调整procState和adjType；
- 当adj==SERVICE_ADJ，确认是否在serviceb中，如果是adj改成SERVICE_B_ADJ；
- 其他的限制确认；
这里弄个简单的流程图，方便记忆：
12.1 bind类型
| binder类型 | 说明 |
|---|---|
| BIND_WAIVE_PRIORITY | 不会影响服务的进程优先级，像通用的应用进程一样将服务放在一个LRU表中 |
| BIND_TREAT_LIKE_ACTIVITY | 将binding 视为持有一个activity，unbinding视为activity在后台，这个通常用在输入法进程，以便更快捷的切换键盘。 |
| BIND_ALLOW_OOM_MANAGEMENT | 保持服务受默认的服务管理器管理，当内存不足时候，会销毁服务 |
| BIND_ABOVE_CLIENT | 设置服务的进程优先级高于客户端的优先级，只有当需要服务晚于客户端被销毁这种情况才这样设置 |
| BIND_IMPORTANT | 标识服务对客户端是非常重要的，会将服务提升至前台进程优先级，通常情况下，即时客户端是前台优先级，服务最多也只能被提升至可见进程优先级 |
| BIND_NOT_FOREGROUND | 不会将被绑定的服务提升到前台优先级，但是这个服务也至少会和客户端在内存中优先级是相同的 |
| BIND_SCHEDULE_LIKE_TOP_APP | 此标志仅用于系统调整IME（以及与top应用程序紧密配合的任何进程外用户可见组件）的调度策略。所以托管此类服务的UI能够拥有top app一样的调度策略。仅限于系统调用，否则会抛出安全异常 |
| BIND_ADJUST_WITH_ACTIVITY | Service的优先级将相对于其绑定的Activity，Activity到前台，则Service优先级相对提升，Activity到后台，则Servcie优先级相对降低 |
| BIND_AUTO_CREATE | 绑定服务时候，如果服务尚未创建，服务会自动创建 |
13. ApplyOomAdjLocked()
private final boolean applyOomAdjLocked(ProcessRecord app, boolean doingAll, long now,
long nowElapsed) {
boolean success = true;
// setAdj 上次设置的adj
// curAdj 当前的adj
// setRawAdj 上一次设置的 unlimit adj
// curRawAdj 当前unlimit adj
if (app.getCurRawAdj() != app.setRawAdj) {
app.setRawAdj = app.getCurRawAdj();
}
int changes = 0;
// 在bootup 阶段不压缩
// useCompaction() 是app compact是否使能
if (mCachedAppOptimizer.useCompaction() && mService.mBooted) {
// 如果跟上次的adj 不一样，有变化
if (app.curAdj != app.setAdj) {
// 当app从perceptible变为home/previous，执行some等级内存压缩
// 当app变成cached，执行full等级内存压缩
if (app.setAdj <= ProcessList.PERCEPTIBLE_APP_ADJ &&
(app.curAdj == ProcessList.PREVIOUS_APP_ADJ ||
app.curAdj == ProcessList.HOME_APP_ADJ)) {
mCachedAppOptimizer.compactAppSome(app);
} else if ((app.setAdj < ProcessList.CACHED_APP_MIN_ADJ
|| app.setAdj > ProcessList.CACHED_APP_MAX_ADJ)
&& app.curAdj >= ProcessList.CACHED_APP_MIN_ADJ
&& app.curAdj <= ProcessList.CACHED_APP_MAX_ADJ) {
mCachedAppOptimizer.compactAppFull(app);
}
} else if (mService.mWakefulness != PowerManagerInternal.WAKEFULNESS_AWAKE //非唤醒状态
&& app.setAdj < ProcessList.FOREGROUND_APP_ADJ
&& mCachedAppOptimizer.shouldCompactPersistent(app, now)) {
//处于非唤醒状态，且上一次重要性高于前台进程adj，
// 且上一次压缩的时间已经尝过10min或者上次没压缩都返回true，
// 进行persistent 级别压缩
mCachedAppOptimizer.compactAppPersistent(app);
} else if (mService.mWakefulness != PowerManagerInternal.WAKEFULNESS_AWAKE
&& app.getCurProcState()
== ActivityManager.PROCESS_STATE_BOUND_FOREGROUND_SERVICE
&& mCachedAppOptimizer.shouldCompactBFGS(app, now)) {
// 非唤醒状态，且当前进程状态为绑定一个前台service进程
// 且上一次压缩的时间已经超过10min或上一次没压缩都返回true
mCachedAppOptimizer.compactAppBfgs(app);
}
}
// 当 adj当前值与上一次不一致时，发生变化
if (app.curAdj != app.setAdj) {
// setOomAdj() 通知lmkd
ProcessList.setOomAdj(app.pid, app.uid, app.curAdj);
app.setAdj = app.curAdj;
app.verifiedAdj = ProcessList.INVALID_ADJ;
synchronized (mCachedAppOptimizer) {
app.mSetAdjForCompact = app.setAdj;
}
}
final int curSchedGroup = app.getCurrentSchedulingGroup();
// schedGroup 发生了变化
if (app.setSchedGroup != curSchedGroup) {
int oldSchedGroup = app.setSchedGroup;
app.setSchedGroup = curSchedGroup;
//进程等待被kill，且当前进程关联的广播为空，
// 且上一次设置的schedGroup为SCHED_GROUP_BACKGROUND，进行kill处理，
// 且标记此次 applyOom 失败
if (app.waitingToKill != null && app.curReceivers.isEmpty()
&& app.setSchedGroup == ProcessList.SCHED_GROUP_BACKGROUND) {
app.kill(app.waitingToKill, ApplicationExitInfo.REASON_USER_REQUESTED,
ApplicationExitInfo.SUBREASON_UNKNOWN, true);
success = false;
} else {
int processGroup;
switch (curSchedGroup) {
case ProcessList.SCHED_GROUP_BACKGROUND:
processGroup = THREAD_GROUP_BACKGROUND;
break;
case ProcessList.SCHED_GROUP_TOP_APP:
case ProcessList.SCHED_GROUP_TOP_APP_BOUND:
processGroup = THREAD_GROUP_TOP_APP;
break;
case ProcessList.SCHED_GROUP_RESTRICTED:
processGroup = THREAD_GROUP_RESTRICTED;
break;
default:
processGroup = THREAD_GROUP_DEFAULT;
break;
}
mProcessGroupHandler.sendMessage(mProcessGroupHandler.obtainMessage(
0 /* unused */, app.pid, processGroup, app.processName));
try {
if (curSchedGroup == ProcessList.SCHED_GROUP_TOP_APP) {
// do nothing if we already switched to RT
if (oldSchedGroup != ProcessList.SCHED_GROUP_TOP_APP) {
app.getWindowProcessController().onTopProcChanged();
if (mService.mUseFifoUiScheduling) {
// Switch UI pipeline for app to SCHED_FIFO
app.savedPriority = Process.getThreadPriority(app.pid);
mService.scheduleAsFifoPriority(app.pid, /* suppressLogs */true);
if (app.renderThreadTid != 0) {
mService.scheduleAsFifoPriority(app.renderThreadTid,
/* suppressLogs */true);
if (DEBUG_OOM_ADJ) {
Slog.d("UI_FIFO", "Set RenderThread (TID " +
app.renderThreadTid + ") to FIFO");
}
} else {
if (DEBUG_OOM_ADJ) {
Slog.d("UI_FIFO", "Not setting RenderThread TID");
}
}
} else {
// Boost priority for top app UI and render threads
setThreadPriority(app.pid, TOP_APP_PRIORITY_BOOST);
if (app.renderThreadTid != 0) {
try {
setThreadPriority(app.renderThreadTid,
TOP_APP_PRIORITY_BOOST);
} catch (IllegalArgumentException e) {
// thread died, ignore
}
}
}
}
} else if (oldSchedGroup == ProcessList.SCHED_GROUP_TOP_APP &&
curSchedGroup != ProcessList.SCHED_GROUP_TOP_APP) {
app.getWindowProcessController().onTopProcChanged();
if (mService.mUseFifoUiScheduling) {
try {
// Reset UI pipeline to SCHED_OTHER
setThreadScheduler(app.pid, SCHED_OTHER, 0);
setThreadPriority(app.pid, app.savedPriority);
if (app.renderThreadTid != 0) {
setThreadScheduler(app.renderThreadTid,
SCHED_OTHER, 0);
}
} catch (IllegalArgumentException e) {
Slog.w(TAG,
"Failed to set scheduling policy, thread does not exist:\n"
+ e);
} catch (SecurityException e) {
Slog.w(TAG, "Failed to set scheduling policy, not allowed:\n" + e);
}
} else {
// Reset priority for top app UI and render threads
setThreadPriority(app.pid, 0);
}
if (app.renderThreadTid != 0) {
setThreadPriority(app.renderThreadTid, THREAD_PRIORITY_DISPLAY);
}
}
} catch (Exception e) {
if (DEBUG_ALL) {
Slog.w(TAG, "Failed setting thread priority of " + app.pid, e);
}
}
}
}
if (app.repForegroundActivities != app.hasForegroundActivities()) {
app.repForegroundActivities = app.hasForegroundActivities();
changes |= ActivityManagerService.ProcessChangeItem.CHANGE_ACTIVITIES;
}
// 更新app 的冻结状态
updateAppFreezeStateLocked(app);
// 如果进程状态发成变化，更新下进程状态
if (app.getReportedProcState() != app.getCurProcState()) {
app.setReportedProcState(app.getCurProcState());
if (app.thread != null) {
try {
if (false) {
//RuntimeException h = new RuntimeException("here");
Slog.i(TAG, "Sending new process state " + app.getReportedProcState()
+ " to " + app /*, h*/);
}
app.thread.setProcessState(app.getReportedProcState());
} catch (RemoteException e) {
}
}
}
// 执行pss统计操作，以及计算下一次pss的时间
if (app.setProcState == PROCESS_STATE_NONEXISTENT
|| ProcessList.procStatesDifferForMem(app.getCurProcState(), app.setProcState)) {
if (false && mService.mTestPssMode
&& app.setProcState >= 0 && app.lastStateTime <= (now-200)) {
// Experimental code to more aggressively collect pss while
// running test... the problem is that this tends to collect
// the data right when a process is transitioning between process
// states, which will tend to give noisy data.
long start = SystemClock.uptimeMillis();
long startTime = SystemClock.currentThreadTimeMillis();
long pss = Debug.getPss(app.pid, mTmpLong, null);
long endTime = SystemClock.currentThreadTimeMillis();
mService.recordPssSampleLocked(app, app.getCurProcState(), pss,
mTmpLong[0], mTmpLong[1], mTmpLong[2],
ProcessStats.ADD_PSS_INTERNAL_SINGLE, endTime-startTime, now);
mService.mPendingPssProcesses.remove(app);
Slog.i(TAG, "Recorded pss for " + app + " state " + app.setProcState
+ " to " + app.getCurProcState() + ": "
+ (SystemClock.uptimeMillis()-start) + "ms");
}
app.lastStateTime = now;
app.nextPssTime = ProcessList.computeNextPssTime(app.getCurProcState(),
app.procStateMemTracker, mService.mTestPssMode,
mService.mAtmInternal.isSleeping(), now);
if (DEBUG_PSS) Slog.d(TAG_PSS, "Process state change from "
+ ProcessList.makeProcStateString(app.setProcState) + " to "
+ ProcessList.makeProcStateString(app.getCurProcState()) + " next pss in "
+ (app.nextPssTime-now) + ": " + app);
} else {
if (now > app.nextPssTime || (now > (app.lastPssTime+ProcessList.PSS_MAX_INTERVAL)
&& now > (app.lastStateTime+ProcessList.minTimeFromStateChange(
mService.mTestPssMode)))) {
if (mService.requestPssLocked(app, app.setProcState)) {
app.nextPssTime = ProcessList.computeNextPssTime(app.getCurProcState(),
app.procStateMemTracker, mService.mTestPssMode,
mService.mAtmInternal.isSleeping(), now);
}
} else if (false && DEBUG_PSS) {
Slog.d(TAG_PSS,
"Not requesting pss of " + app + ": next=" + (app.nextPssTime-now));
}
}
if (app.setProcState != app.getCurProcState()) {
if (DEBUG_SWITCH || DEBUG_OOM_ADJ || mService.mCurOomAdjUid == app.uid) {
String msg = "Proc state change of " + app.processName
+ " to " + ProcessList.makeProcStateString(app.getCurProcState())
+ " (" + app.getCurProcState() + ")" + ": " + app.adjType;
reportOomAdjMessageLocked(TAG_OOM_ADJ, msg);
}
boolean setImportant = app.setProcState < PROCESS_STATE_SERVICE;
boolean curImportant = app.getCurProcState() < PROCESS_STATE_SERVICE;
if (setImportant && !curImportant) {
// This app is no longer something we consider important enough to allow to use
// arbitrary amounts of battery power. Note its current CPU time to later know to
// kill it if it is not behaving well.
app.setWhenUnimportant(now);
app.lastCpuTime = 0;
}
// Inform UsageStats of important process state change
// Must be called before updating setProcState
maybeUpdateUsageStatsLocked(app, nowElapsed);
maybeUpdateLastTopTime(app, now);
app.setProcState = app.getCurProcState();
if (app.setProcState >= ActivityManager.PROCESS_STATE_HOME) {
app.notCachedSinceIdle = false;
}
if (!doingAll) {
mService.setProcessTrackerStateLocked(app,
mService.mProcessStats.getMemFactorLocked(), now);
} else {
app.procStateChanged = true;
}
} else if (app.reportedInteraction && (nowElapsed - app.getInteractionEventTime())
> mConstants.USAGE_STATS_INTERACTION_INTERVAL) {
// For apps that sit around for a long time in the interactive state, we need
// to report this at least once a day so they don't go idle.
maybeUpdateUsageStatsLocked(app, nowElapsed);
} else if (!app.reportedInteraction && (nowElapsed - app.getFgInteractionTime())
> mConstants.SERVICE_USAGE_INTERACTION_TIME) {
// For foreground services that sit around for a long time but are not interacted with.
maybeUpdateUsageStatsLocked(app, nowElapsed);
}
if (app.curCapability != app.setCapability) {
changes |= ActivityManagerService.ProcessChangeItem.CHANGE_CAPABILITY;
app.setCapability = app.curCapability;
}
if (changes != 0) {
if (DEBUG_PROCESS_OBSERVERS) Slog.i(TAG_PROCESS_OBSERVERS,
"Changes in " + app + ": " + changes);
ActivityManagerService.ProcessChangeItem item =
mService.enqueueProcessChangeItemLocked(app.pid, app.info.uid);
item.changes |= changes;
item.foregroundActivities = app.repForegroundActivities;
item.capability = app.setCapability;
if (DEBUG_PROCESS_OBSERVERS) Slog.i(TAG_PROCESS_OBSERVERS,
"Item " + Integer.toHexString(System.identityHashCode(item))
+ " " + app.toShortString() + ": changes=" + item.changes
+ " foreground=" + item.foregroundActivities
+ " type=" + app.adjType + " source=" + app.adjSource
+ " target=" + app.adjTarget + " capability=" + item.capability);
}
return success;
}又是一段很长逻辑的代码，分析起来特别的类，主要经历如下流程：
- 当启动boot 完成且app compaction 使能，则进行app 压缩确认，满足条件会进行内存压缩；
- 当app 的adj 发生变化，通过setOomAdj() 通知 lmkd(采用 socket通信方式)；
- 当schedGroup 发生变化时，更新进程的scheduler 和priority，特殊的情况会被kill；
- 调用 updateAppFreezeStateLocked() 函数更新app 的冻结状态；
- 设置进程的 process state；
- 执行pss 统计操作，计算下一次 pss 时间；
13.1 Framework 调度策略
进程优先级级别：
- process.setThreadPriority(int tid, int priority);
组优先级：
- setProcessGroup(int pid, int group);
- setThreadGroup(int tid, int group);
调度器类别：
- setThreadScheduler(int tid, int policy, int prioriy);
| 进程优先级 | nice 值 | 说明 |
|---|---|---|
| THREAD_PRIORITY_LOWEST | 19 | 最低优先级 |
| THREAD_PRIORITY_BACKGROUND | 10 | 后台 |
| THREAD_PRIORITY_LESS_FAVORABLE | 1 | 比默认略低 |
| THREAD_PRIORITY_DEFAULT | 0 | 默认 |
| THREAD_PRIORITY_MORE_FAVORABLE | -1 | 比默认略高 |
| THREAD_PRIORITY_FOREGROUND | -2 | 前台 |
| THREAD_PRIORITY_DISPLAY | -4 | 显示相关 |
| THREAD_PRIORITY_URGENT_DISPLAY | -8 | 显示(更为重要)，input 事件 |
| TOP_APP_PRIORITY_BOOST | -10 | 前台进程的主线程和render 线程boost 优先级 |
| THREAD_PRIORITY_AUDIO | -16 | 音频相关 |
| THREAD_PRIORITY_URGENT_AUDIO | -19 | 音频(更重要) |
| 组优先级 | 取值 | 说明 |
|---|---|---|
| THREAD_GROUP_DEFAULT | -1 | 仅用于setProcessGroup，将优先级<=10的进程提升到-2 |
| THREAD_GROUP_BG_NONINTERACTIVE | 0 | CPU分时的时长缩短 |
| THREAD_GROUP_FOREGROUND | 1 | CPU分时的时长正常 |
| THREAD_GROUP_SYSTEM | 2 | 系统线程组 |
| THREAD_GROUP_AUDIO_APP | 3 | 应用程序音频 |
| THREAD_GROUP_AUDIO_SYS | 4 | 系统程序音频 |
| 调度器 | 名称 | 说明 |
|---|---|---|
| SCHED_OTHER | 默认 | 标准round-robin分时共享策略 |
| SCHED_BATCH | 批处理调度 | 针对具有batch风格（批处理）进程的调度策略 |
| SCHED_IDLE | 空闲调度 | 针对优先级非常低的适合在后台运行的进程 |
| SCHED_FIFO | 先进先出 | 实时调度策略 |
| SCHED_RR | 循环调度 | 实时调度策略 |
13.2 updateLruProcessLocked()
AMS中有一个LRU列表mProcessList经过AMS启动的每一个进程，都会加入到LRU列表中进行管理，这个LRU列表并不是随意排序或者说按加入的时间顺序进行排布的，而是有一定的逻辑进行计算，而后根据每个进程的实时动态状态进行改变的。
mProcessList这个LRU列表的定义其实最终在ProcessList.java中，AMS中定义了一个processList的实体，并且在整个系统中只有一个这样的LRU列表专门用于管理AMS启动的所有进程。
AMS中有一个成员变量 mLruProcesses，所有通过ams启动的java进程都会记录在里面，按照进程的使用时间以及进程种类，按照重要性由低到高排序，即越重要在 arraylist 中的index越大kill的时候也是先 kill index 小的进程， 总体来说index从小到大放置3类的进程：其他进程、含有service组件的进程、和activity有关的进程（包含 activity 或 client 包含 activity ）
调用 updateLruProcessLocked 更新LRU列表的地方：
- ASM 启动一个进程的时候
- 绑定/解绑服务：bindserviceLocked
- start/kill service的时候
- remove connection的时候
- update processInfo的时候
- 处理boardCastor receive的时候
- setSystemProcess的时候
- getContentProvider和addApp(AMS启动新进程的方法)的时候
LRU列表更新的逻辑如下：
- 首先LRU列表被分为三段，这三段分别放置带activity的进程，带service的进程以及其他以外的进程，使用两个标志mLruProcessServiceStart和mLruProcessActivityStart间隔开；其中，mLruProcessServiceStart表示带service的那一段进程的开始，如图所示，mLruProcessActivityStart表示带activity的那一段进程的开始，如图所示；这样区分是为了让LRU列表尾部的进程变得更重要，而头部就没这么重要；所以LRU列表中的进程重要性是从头到位逐步递增的。
- 在对一个进程进行逻辑计算adj值时，会对其所处的当前状态进行分析，判断其是否带有一些提升自身重要性的一些组件（带有activity，service或者provider等等），将其对应的分到三段进程中的某一段；
- 当进程被分到其对应的那一段进程的时候，其插入点默认都是那一段的尾部开始插入的；比如，当一个进程A，带有service时，他就被分到hasService这一段进程列表中，如果他本身就已经在LRU列表中（即不是新启动的进程），需要将其先从LRU列表删除，再将其插入到hasService这一段LRU列表的尾部，即mLruProcessActivityStart的前一个位置；如果他是新启动的进程，即原先不在LRU列表中，则直接找到对应的地方插入即可，而不必删除原先的进程
- 值得注意的是，mLruProcessServiceStart和mLruProcessActivityStart这两个标志是用于间隔开other，hasService和hasActivity列表的，所以任何一个对LRU列表进行的操作都要及时更新这两个标志位的位置（这两个标志位其实就相当于两个指针，用于插入一个新的进程时使用）
- AMS在更新所有的进程的adj的时候，都会调用updateLruProcessLocked 方法对LRU列表进行更新，实时更新每一个进程在LRU列表的位置，每一个进程一旦其状态有所改变（前后台切换，service切换等），其在LRU列表中的位置都将会被修改到合适的位置。
- 在对进程进行插入的时候，为什么要从尾部进行插入？？？之前说过，LRU列表中，进程的重要性都是从头到尾逐步增加的；也即是说这三段列表中，尾部的进程都是最重要的，头部的是没有这么重要的。当一个进程的状态被更新，其在LRU列表中的位置被更新，代表该进程最近的状态有被修改过，也就是说这个进程最近是有活跃过的；这样，每一次更新进程在LRU列表中的位置，都表示被更新的进程是最新的（最近活跃的），这样子逐步更新之后，那些老的进程，不活跃的，其状态没有改变，那么他在LRU列表中的位置就会逐步被沉淀到列表尾部，进一步变老，其重要性就越来越显得不这么重要了。就这样，经过逐步的迭代更新，最终LRU列表维护的进程都是越靠近尾部越重要的。
参考：
https://blog.csdn.net/zhzhangnews/article/details/110474461
