今天來寫一個關於LeakCanary-1.5.0的一些心得;我們移動端性能方面第一個就想到使用LeakCanary;但是很多使用LeakCanary無法解析,以及LeakCanary在不同手機上面也會有不同的一些提示;我這邊自己抽了一些時間,對LeakCanary的架構進行分析,以及代碼的實現過程進行分析;不知道一篇能不能寫完:下面先上一個圖;
這個是自己畫的LeakCanary的uml圖;僅僅畫了初始化的地方;這邊會從這個圖一步步解析LeakCanary的作用;首先我們先看到LeakCanary的初始化
1)install(Application application)初始化方法
public static RefWatcher install(Application application) {
return refWatcher(application).listenerServiceClass(DisplayLeakService.class)
.excludedRefs(AndroidExcludedRefs.createAppDefaults().build())
.buildAndInstall();
}
public static AndroidRefWatcherBuilder refWatcher(Context context) {
return new AndroidRefWatcherBuilder(context);
}
其中new 一個AndroidRefWatcherBuilder對象,開始註冊listenerServiceClass並且註冊一個ExcludedRefs,最後進行組裝;
其中buildAndInstall方法裏面涉及到了Application註冊Activity的生命週期;主要在生命週期的裏面的onActivityDestroyed裏面進行觸發一個方法ActivityRefWatcher.this.onActivityDestroyed(activity);
2)我們開始分析,第一步new AndroidRefWatcherBuilder並且設置ApplicationContext;
3)設置listenerServiceClass;其中傳入了DisplayLeakService.class;(專門處理heapDump文件)
DisplayLeakService的父類是AbstractAnalysisResultService,AbstractAnalysisResultService的父類是IntentService。其實走到這一步;大概能看出來做一個異步的耗時操作了;肯定是在onHandleIntent(Intent intent);並且sendResultToListener是進行發送耗時操作的方式;獲取heapDump文件,進行分析;重寫onHeapAnalyzed方法,具體在DisplayLeakService實現;(具體實現後面分析)
4) 獲取AndroidExcludedRefs;創建ExcludedRefs對象;裏面更多包含的是配置
先看一下createAndroidDefaults方法;其中裏面默認實現了SOFT_REFERENCES, FINALIZER_WATCHDOG_DAEMON, MAIN, LEAK_CANARY_THREAD, EVENT_RECEIVER__MMESSAGE_QUEUE;
A) SOFT_REFERENCES:
a.註冊軟引用的類名
b.註冊弱引用的類名
c.註冊虛引用的類名
d.註冊Finalizer的類名(GC: 從一個對象變得不可達開始,到執行它的finalizer方法,時間可能任意長)
f.註冊FinalizerReference的類名(class類裏面定義finalize方法,就會創建)
B)FINALIZER_WATCHDOG_DAEMON:
a.註冊FinalizerWatchdogDaemon線程名稱(回收的線程)
C)MAIN
a.註冊主線程名稱
D)LEAK_CANARY_THREAD
a.註冊LeakCanary的工作線程名稱
E)EVENT_RECEIVER__MMESSAGE_QUEUE
a.註冊android.view.Choreographer$FrameDisplayEventReceiver以及mMessageQueue;應該是需要繼承修改;後續在看
F)剩下的其他和機型;Api相關。是針對某一個Api遇到內存泄露作出的指定捕獲,或者刨除;這邊也是後續抽一個例子細看
這個類使用的是 EnumSet.allOf 該方法接受一個元素類型的參數elementType,並引用其元素將存儲到集合中的類對象;
5)buildAndInstall()方法
調用這個方法的時候;判斷是否是初始化默認的DISABLED;這個位子後續說;這邊不是;所以走下面的代碼;
public RefWatcher buildAndInstall() {
RefWatcher refWatcher = build();
if (refWatcher != DISABLED) {
LeakCanary.enableDisplayLeakActivity(context);
ActivityRefWatcher.installOnIcsPlus((Application) context, refWatcher);
}
return refWatcher;
}
走到enableDisplayLeakActivity方法;
public static void enableDisplayLeakActivity(Context context) {
setEnabled(context, DisplayLeakActivity.class, true);
}
裏面開啓類一個單核心線程
public static void setEnabled(Context context, final Class<?> componentClass,
final boolean enabled) {
final Context appContext = context.getApplicationContext();
executeOnFileIoThread(new Runnable() {
@Override public void run() {
setEnabledBlocking(appContext, componentClass, enabled);
}
});
}
來處理setEnabledBlocking方法;
public static void setEnabledBlocking(Context appContext, Class<?> componentClass,
boolean enabled) {
ComponentName component = new ComponentName(appContext, componentClass);
PackageManager packageManager = appContext.getPackageManager();
int newState = enabled ? COMPONENT_ENABLED_STATE_ENABLED : COMPONENT_ENABLED_STATE_DISABLED;
// Blocks on IPC.
packageManager.setComponentEnabledSetting(component, newState, DONT_KILL_APP);
}
其中packageManager.setComponentEnabledSetting(component, newState, DONT_KILL_APP);來控制啓用 禁用 四大組件
由上面代碼裏面 對DisplayLeakActivity進行設置成----可用狀態,並且不殺死APP(明顯是在處理Activity的)
下面在走 installOnIcsPlus 方法;
其中SDK低於14的不進行初始化觀察;
public static void installOnIcsPlus(Application application, RefWatcher refWatcher) {
if (SDK_INT < ICE_CREAM_SANDWICH) {
// If you need to support Android < ICS, override onDestroy() in your base activity.
return;
}
ActivityRefWatcher activityRefWatcher = new ActivityRefWatcher(application, refWatcher);
activityRefWatcher.watchActivities();
}
其中使用Application進行註冊Activity生命週期,所以Fragment的泄露希望是自己去調用
private final Application.ActivityLifecycleCallbacks lifecycleCallbacks =
new Application.ActivityLifecycleCallbacks() {
@Override public void onActivityCreated(Activity activity, Bundle savedInstanceState) {
}
@Override public void onActivityStarted(Activity activity) {
}
@Override public void onActivityResumed(Activity activity) {
}
@Override public void onActivityPaused(Activity activity) {
}
@Override public void onActivityStopped(Activity activity) {
}
@Override public void onActivitySaveInstanceState(Activity activity, Bundle outState) {
}
@Override public void onActivityDestroyed(Activity activity) {
ActivityRefWatcher.this.onActivityDestroyed(activity);
}
};
在裏面執行了onActivityDestroyed方法;
剛剛在上面沒有提到buildAndInstall方法裏面的build;現在我們回過來講一下;因爲我們現在已經知道了,這個LeakCanary觸發的時機;
public final RefWatcher build() {
if (isDisabled()) {
return RefWatcher.DISABLED;
}
//1
ExcludedRefs excludedRefs = this.excludedRefs;
if (excludedRefs == null) {
excludedRefs = defaultExcludedRefs();
}
//2
HeapDump.Listener heapDumpListener = this.heapDumpListener;
if (heapDumpListener == null) {
heapDumpListener = defaultHeapDumpListener();
}
//3
DebuggerControl debuggerControl = this.debuggerControl;
if (debuggerControl == null) {
debuggerControl = defaultDebuggerControl();
}
//4
HeapDumper heapDumper = this.heapDumper;
if (heapDumper == null) {
heapDumper = defaultHeapDumper();
}
// 5
WatchExecutor watchExecutor = this.watchExecutor;
if (watchExecutor == null) {
watchExecutor = defaultWatchExecutor();
}
// 6
GcTrigger gcTrigger = this.gcTrigger;
if (gcTrigger == null) {
gcTrigger = defaultGcTrigger();
}
return new RefWatcher(watchExecutor, debuggerControl, gcTrigger, heapDumper, heapDumpListener,
excludedRefs);
}
我們先看到 :
1 是ExcludedRefs對象的賦值;從uml圖裏面可以看到子類AndroidRefWatcherBuilder和父類RefWatcherBuilder;在初始化的時候調用的就是對父類this.excludedRefs賦值;
2是AndroidRefWatcherBuilder子類裏面調用父類的heapDumpListener方法賦值this.heapDumpListener
3是AndroidRefWatcherBuilder類裏面重寫子類的defaultDebuggerControl方法,裏面獲取是否是被調試狀態:Debug.isDebuggerConnected()
4 是AndroidRefWatcherBuilder類裏面重寫子類的defaultHeapDumper方法 (下面細講)
5 是AndroidRefWatcherBuilder類裏面重寫子類的defaultWatchExecutor方法,初始化AndroidWatchExecutor延遲5000毫秒
(專門開了一個工作線程處理)
6 是AndroidRefWatcherBuilder類裏面 使用默認的GcTrigger(做GC操作的)
然後組裝到RefWatcher裏面去;下面我們開始講解一下整個工作的流程;以及重點的實現部分
現在開走;實現的內存泄露檢測流程
當Activity涉及到destory時
void onActivityDestroyed(Activity activity) {
refWatcher.watch(activity);
}
調用watch方法
public void watch(Object watchedReference, String referenceName) {
if (this == DISABLED) {
return;
}
checkNotNull(watchedReference, "watchedReference");//校驗不爲null
checkNotNull(referenceName, "referenceName");//校驗不爲null
final long watchStartNanoTime = System.nanoTime();//納秒
String key = UUID.randomUUID().toString();//唯一標識碼
retainedKeys.add(key);//緩存起來
final KeyedWeakReference reference =
new KeyedWeakReference(watchedReference, key, referenceName, queue);//生成weak;配置一個key和name(name看起來是空值),加到隊列裏面去,繼承WeakReference
ensureGoneAsync(watchStartNanoTime, reference);//實現runable的方法;
}
private void ensureGoneAsync(final long watchStartNanoTime, final KeyedWeakReference reference) {
watchExecutor.execute(new Retryable() {//watchExecutor上面說的設置一個工作線程;
//判斷是否是主線程; 如果是的話,直接addIdleHandler(CPU空閒的時候會調用)然後執行run();(有重試機制)都是延時操作
// 如果不是主線程,先post回主線程,addIdleHandler(CPU空閒的時候會調用)然後執行run();(有重試機制)都是延時操作
@Override public Retryable.Result run() {
return ensureGone(reference, watchStartNanoTime);//RETRY會進行重試
}
});
}
Retryable.Result ensureGone(final KeyedWeakReference reference, final long watchStartNanoTime) {
long gcStartNanoTime = System.nanoTime();//獲取納秒
long watchDurationMs = NANOSECONDS.toMillis(gcStartNanoTime - watchStartNanoTime);//計算出來耗時多久
removeWeaklyReachableReferences();//移除隊列裏面的值,以及對應的retainedKeys的name 重要1
if (debuggerControl.isDebuggerAttached()) {//判斷是否在調試,如果是調試的返回重試
// The debugger can create false leaks.
return RETRY;
}
if (gone(reference)) {//如果retainedKeys沒有緩存的reference的話,不做操作
return DONE;
}
gcTrigger.runGc();//表示有reference,進行GC操作 重要2
//Runtime.getRuntime().gc(); 發起GC操作
//Thread.sleep(100);//等待 100毫秒
//System.runFinalization();//運行處於掛起終止狀態的所有對象的終止方法。
//調用該方法說明 Java 虛擬機做了一些努力運行已被丟棄對象的 finalize 方法,但是這些對象的 finalize 方法至今尚未運行。當控制權從方法調用中返回時,Java 虛擬機已經盡最大努力去完成所有未執行的終止方法。
removeWeaklyReachableReferences();//移除隊列裏面的值,以及對應的retainedKeys的name
if (!gone(reference)) {//如果這個時候,隊列裏面的reference被移除了,但是retainedKeys還是包含reference,進行下一步內存泄露分析,如果沒有表示被回收了;重要 3
long startDumpHeap = System.nanoTime();//再來一個納秒
long gcDurationMs = NANOSECONDS.toMillis(startDumpHeap - gcStartNanoTime);//計算耗時
File heapDumpFile = heapDumper.dumpHeap();//生成heap dump文件,並且保存起來;看 AndroidHeapDumper類 重要4
if (heapDumpFile == RETRY_LATER) {//如果是重試,進行重試操作
// Could not dump the heap.
return RETRY;
}
long heapDumpDurationMs = NANOSECONDS.toMillis(System.nanoTime() - startDumpHeap);//計算耗時
heapdumpListener.analyze(
new HeapDump(heapDumpFile, reference.key, reference.name, excludedRefs, watchDurationMs,
gcDurationMs, heapDumpDurationMs));//開始分析,看ServiceHeapDumpListener 類 ->HeapAnalyzerService類 重要5
}
return DONE;
}
重點說明:(這個操作是線程空餘狀態進行)
重點1:
清空不存在的誤差
重點2:
進行GC的操作,並且還是延遲了
重點3:
是利用緩存,以及隊列的刪除進行判斷是否存在內存泄漏
重點4:
AndroidHeapDumper類:
@Override public File dumpHeap() {
File heapDumpFile = leakDirectoryProvider.newHeapDumpFile();//生成路徑
// 看下面的DefaultLeakDirectoryProvider類newHeapDumpFile();生成路徑不多說明
if (heapDumpFile == RETRY_LATER) {//如果稍後在進行重試;會返回一個標識
return RETRY_LATER;
}
FutureResult<Toast> waitingForToast = new FutureResult<>();
showToast(waitingForToast);//先進行彈框出現內存泄露標誌,這個也是cpu空閒時,緩存該toast
if (!waitingForToast.wait(5, SECONDS)) {//併發
CanaryLog.d("Did not dump heap, too much time waiting for Toast.");
return RETRY_LATER;
}
Toast toast = waitingForToast.get();//獲取toat
try {
Debug.dumpHprofData(heapDumpFile.getAbsolutePath());//Debug.dumpHprofData 生成heap dump文件,後面是路徑;//目標找到了,這個是生成文件
cancelToast(toast);//取消彈窗
return heapDumpFile;//返回寫入的路徑
} catch (Exception e) {
CanaryLog.d(e, "Could not dump heap");
// Abort heap dump
return RETRY_LATER;//失敗了重試
}
}
裏面生成了真正的dump的對象,以及解析的類
重點5:
ServiceHeapDumpListener 類 ->HeapAnalyzerService類
@Override protected void onHandleIntent(Intent intent) {
if (intent == null) {
CanaryLog.d("HeapAnalyzerService received a null intent, ignoring.");
return;
}
String listenerClassName = intent.getStringExtra(LISTENER_CLASS_EXTRA);
HeapDump heapDump = (HeapDump) intent.getSerializableExtra(HEAPDUMP_EXTRA);
HeapAnalyzer heapAnalyzer = new HeapAnalyzer(heapDump.excludedRefs);//輸入信息類
AnalysisResult result = heapAnalyzer.checkForLeak(heapDump.heapDumpFile, heapDump.referenceKey);//TODO 1 檢測內存泄漏,以及生成result
AbstractAnalysisResultService.sendResultToListener(this, listenerClassName, heapDump, result);
//TODO 2 DisplayLeakService 也是一樣開啓一個IntentService處理 onHeapAnalyzed方法裏面
}
這個類操作之後,到DisplayLeakService 這個進行最後的數據小處理,以及彈通知操作
下面細講一下TODO:
TODO 1:
HeapAnalyzer類:這個是我們非常關鍵的類。因爲會涉及到我們判斷哪一些不需要寫入;不需要生成泄漏文件;所以上面的配置類很重要
public AnalysisResult checkForLeak(File heapDumpFile, String referenceKey) {//確定一下是否是內存泄露
long analysisStartNanoTime = System.nanoTime();//納秒
if (!heapDumpFile.exists()) {//判斷文件是否存在;不存在的話,進行返回失敗操作
Exception exception = new IllegalArgumentException("File does not exist: " + heapDumpFile);
return failure(exception, since(analysisStartNanoTime));
}
try {
HprofBuffer buffer = new MemoryMappedFileBuffer(heapDumpFile);//MemoryMappedFileBuffer 將heapDumpFile傳入,生成HprofBuffer,這個到haha的那個庫,後續分析
HprofParser parser = new HprofParser(buffer);//轉碼,也是haha
Snapshot snapshot = parser.parse();//這幾個轉化後續在看,上面就是將文件轉化成可以識別的對象
deduplicateGcRoots(snapshot);//生成GC root快照
Instance leakingRef = findLeakingReference(referenceKey, snapshot);//這邊開始查找泄漏Instance
// False alarm, weak reference was cleared in between key check and heap dump.
if (leakingRef == null) {//如果沒找到,表示沒有內存泄漏
return noLeak(since(analysisStartNanoTime));
}
return findLeakTrace(analysisStartNanoTime, snapshot, leakingRef);//有的話,開始繼續查找
} catch (Throwable e) {
return failure(e, since(analysisStartNanoTime));
}
}
/**
* Pruning duplicates reduces memory pressure from hprof bloat added in Marshmallow.
*/
void deduplicateGcRoots(Snapshot snapshot) {
// THashMap has a smaller memory footprint than HashMap.
final THashMap<String, RootObj> uniqueRootMap = new THashMap<>();
final List<RootObj> gcRoots = (ArrayList) snapshot.getGCRoots();//獲取根的gc root(可達性分析法)
for (RootObj root : gcRoots) {//開始遍歷
String key = generateRootKey(root);//轉化成字符串
if (!uniqueRootMap.containsKey(key)) {//排重操作,如果沒有的話,就加進去
uniqueRootMap.put(key, root);
}
}
// Repopulate snapshot with unique GC roots.
gcRoots.clear();//清空
uniqueRootMap.forEach(new TObjectProcedure<String>() {//haha裏面的,這邊應該是轉化成字符串之類的,方便後續識別
@Override public boolean execute(String key) {
return gcRoots.add(uniqueRootMap.get(key));
}
});
}
private String generateRootKey(RootObj root) {
return String.format("%s@0x%08x", root.getRootType().getName(), root.getId());
}
private Instance findLeakingReference(String key, Snapshot snapshot) {//返回找到的referenceKey的KeyedWeakReference泄漏
ClassObj refClass = snapshot.findClass(KeyedWeakReference.class.getName());//看是否包含 KeyedWeakReference這個對象名字(弱引用);對象無法被銷燬導致的
List<String> keysFound = new ArrayList<>();
for (Instance instance : refClass.getInstancesList()) {//haha裏面,進行遍歷
List<ClassInstance.FieldValue> values = classInstanceValues(instance);//獲取 List<FieldValue>
String keyCandidate = asString(fieldValue(values, "key"));
if (keyCandidate.equals(key)) {//看一下是否包含該key名稱的,即referenceKey,有的話就是找到了該泄漏的
return fieldValue(values, "referent");
}
keysFound.add(keyCandidate);
}
throw new IllegalStateException(
"Could not find weak reference with key " + key + " in " + keysFound);
}
private AnalysisResult findLeakTrace(long analysisStartNanoTime, Snapshot snapshot,
Instance leakingRef) {
ShortestPathFinder pathFinder = new ShortestPathFinder(excludedRefs);//之前的配置類;
ShortestPathFinder.Result result = pathFinder.findPath(snapshot, leakingRef);//ShortestPathFinder類
// False alarm, no strong reference path to GC Roots.
if (result.leakingNode == null) {
return noLeak(since(analysisStartNanoTime));
}
LeakTrace leakTrace = buildLeakTrace(result.leakingNode);
String className = leakingRef.getClassObj().getClassName();
// Side effect: computes retained size.
snapshot.computeDominators();
Instance leakingInstance = result.leakingNode.instance;
long retainedSize = leakingInstance.getTotalRetainedSize();
retainedSize += computeIgnoredBitmapRetainedSize(snapshot, leakingInstance);
return leakDetected(result.excludingKnownLeaks, className, leakTrace, retainedSize,
since(analysisStartNanoTime));
}
TODO 2:
DisplayLeakService類,進行發送通知
@Override protected final void onHeapAnalyzed(HeapDump heapDump, AnalysisResult result) {
String leakInfo = leakInfo(this, heapDump, result, true);
CanaryLog.d(leakInfo);
boolean resultSaved = false;
boolean shouldSaveResult = result.leakFound || result.failure != null;
if (shouldSaveResult) {
heapDump = renameHeapdump(heapDump);//生成heapDump
resultSaved = saveResult(heapDump, result);//保存起來。這個會讓另一個頁面去找到該路徑
}
PendingIntent pendingIntent;
String contentTitle;
String contentText;
if (!shouldSaveResult) {
contentTitle = getString(R.string.leak_canary_no_leak_title);
contentText = getString(R.string.leak_canary_no_leak_text);
pendingIntent = null;
} else if (resultSaved) {
pendingIntent = DisplayLeakActivity.createPendingIntent(this, heapDump.referenceKey);
if (result.failure == null) {
String size = formatShortFileSize(this, result.retainedHeapSize);
String className = classSimpleName(result.className);
if (result.excludedLeak) {
contentTitle = getString(R.string.leak_canary_leak_excluded, className, size);
} else {
contentTitle = getString(R.string.leak_canary_class_has_leaked, className, size);
}
} else {
contentTitle = getString(R.string.leak_canary_analysis_failed);
}
contentText = getString(R.string.leak_canary_notification_message);
} else {
contentTitle = getString(R.string.leak_canary_could_not_save_title);
contentText = getString(R.string.leak_canary_could_not_save_text);
pendingIntent = null;
}
// New notification id every second.
int notificationId = (int) (SystemClock.uptimeMillis() / 1000);
showNotification(this, contentTitle, contentText, pendingIntent, notificationId);//發送Notification通知
afterDefaultHandling(heapDump, result, leakInfo);
}
以上是我們使用LeakCanary的基本操作流程;所以這些是我需要了解;後續我們再去分析haha這個庫