Merge "Avoid locks in various singleton HandlerThread types" into main (2bbd28e4) · Commits · e / os / android_frameworks_base

core/java/com/android/internal/os/BackgroundThread.java

+34 −28

Original line number	Diff line number	Diff line
		@@ -32,9 +32,13 @@ import java.util.concurrent.Executor;
		public final class BackgroundThread extends HandlerThread {
		private static final long SLOW_DISPATCH_THRESHOLD_MS = 10_000;
		private static final long SLOW_DELIVERY_THRESHOLD_MS = 30_000;
		private static BackgroundThread sInstance;
		private static Handler sHandler;
		private static HandlerExecutor sHandlerExecutor;

		// Note: These static fields are shadowed in Robolectric, and cannot be easily changed without
		// breaking downstream tests. This makes refactoring or optimization a bit messier than it could
		// be, e.g., using common lazy singleton abstractions or the holder init pattern.
		private static volatile BackgroundThread sInstance;
		private static volatile Handler sHandler;
		private static volatile HandlerExecutor sHandlerExecutor;

		private BackgroundThread() {
		super("android.bg", android.os.Process.THREAD_PRIORITY_BACKGROUND);
		@@ -47,9 +51,14 @@ public final class BackgroundThread extends HandlerThread {
		}
		}

		private static void ensureThreadReadyLocked() {
		private static void ensureThreadReady() {
		// As the executor is assigned and initialized last, we use it to signal full readiness.
		if (sHandlerExecutor != null) {
		return;
		}
		synchronized (BackgroundThread.class) {
		if (sHandlerExecutor == null) {
		ensureThreadStartedLocked();
		if (sHandler == null) {
		// This will block until the looper is initialized on the background thread.
		final Looper looper = sInstance.getLooper();
		looper.setTraceTag(Trace.TRACE_TAG_SYSTEM_SERVER);
		@@ -60,37 +69,34 @@ public final class BackgroundThread extends HandlerThread {
		sHandlerExecutor = new HandlerExecutor(sHandler);
		}
		}
		}

		/**
		* Starts the thread if needed, but doesn't block on thread initialization or readiness.
		*/
		public static void startIfNeeded() {
		if (sInstance == null) {
		synchronized (BackgroundThread.class) {
		ensureThreadStartedLocked();
		}
		}
		}

		@NonNull
		public static BackgroundThread get() {
		synchronized (BackgroundThread.class) {
		ensureThreadReadyLocked();
		ensureThreadReady();
		return sInstance;
		}
		}

		@NonNull
		public static Handler getHandler() {
		synchronized (BackgroundThread.class) {
		ensureThreadReadyLocked();
		ensureThreadReady();
		return sHandler;
		}
		}

		@NonNull
		public static Executor getExecutor() {
		synchronized (BackgroundThread.class) {
		ensureThreadReadyLocked();
		ensureThreadReady();
		return sHandlerExecutor;
		}
		}
		}

core/java/com/android/server/FgThread.java

+15 −28

Original line number	Diff line number	Diff line
		@@ -38,45 +38,32 @@ public final class FgThread extends ServiceThread {
		private static final long SLOW_DISPATCH_THRESHOLD_MS = 100;
		private static final long SLOW_DELIVERY_THRESHOLD_MS = 200;

		private static FgThread sInstance;
		private static Handler sHandler;
		private static HandlerExecutor sHandlerExecutor;
		private static final class NoPreloadHolder {
		private static final FgThread sInstance = new FgThread();
		}

		private final Handler mHandler;
		private final HandlerExecutor mHandlerExecutor;

		private FgThread() {
		super("android.fg", android.os.Process.THREAD_PRIORITY_DEFAULT, true /allowIo/);
		}

		private static void ensureThreadLocked() {
		if (sInstance == null) {
		sInstance = new FgThread();
		sInstance.start();
		final Looper looper = sInstance.getLooper();
		start();
		final Looper looper = getLooper();
		looper.setTraceTag(Trace.TRACE_TAG_SYSTEM_SERVER);
		looper.setSlowLogThresholdMs(
		SLOW_DISPATCH_THRESHOLD_MS, SLOW_DELIVERY_THRESHOLD_MS);
		sHandler = makeSharedHandler(sInstance.getLooper());
		sHandlerExecutor = new HandlerExecutor(sHandler);
		}
		looper.setSlowLogThresholdMs(SLOW_DISPATCH_THRESHOLD_MS, SLOW_DELIVERY_THRESHOLD_MS);
		mHandler = makeSharedHandler(looper);
		mHandlerExecutor = new HandlerExecutor(mHandler);
		}

		public static FgThread get() {
		synchronized (FgThread.class) {
		ensureThreadLocked();
		return sInstance;
		}
		return NoPreloadHolder.sInstance;
		}

		public static Handler getHandler() {
		synchronized (FgThread.class) {
		ensureThreadLocked();
		return sHandler;
		}
		return NoPreloadHolder.sInstance.mHandler;
		}

		public static Executor getExecutor() {
		synchronized (FgThread.class) {
		ensureThreadLocked();
		return sHandlerExecutor;
		}
		return NoPreloadHolder.sInstance.mHandlerExecutor;
		}
		}

services/core/java/com/android/server/IoThread.java

+15 −25

Original line number	Diff line number	Diff line
		@@ -18,6 +18,7 @@ package com.android.server;

		import android.os.Handler;
		import android.os.HandlerExecutor;
		import android.os.Looper;
		import android.os.Trace;

		import java.util.concurrent.Executor;
		@@ -28,42 +29,31 @@ import java.util.concurrent.Executor;
		* (not waiting for data itself, but communicating with network daemons).
		*/
		public final class IoThread extends ServiceThread {
		private static IoThread sInstance;
		private static Handler sHandler;
		private static HandlerExecutor sHandlerExecutor;
		private static final class NoPreloadHolder {
		private static final IoThread sInstance = new IoThread();
		}

		private final Handler mHandler;
		private final HandlerExecutor mHandlerExecutor;

		private IoThread() {
		super("android.io", android.os.Process.THREAD_PRIORITY_DEFAULT, true /allowIo/);
		}

		private static void ensureThreadLocked() {
		if (sInstance == null) {
		sInstance = new IoThread();
		sInstance.start();
		sInstance.getLooper().setTraceTag(Trace.TRACE_TAG_SYSTEM_SERVER);
		sHandler = makeSharedHandler(sInstance.getLooper());
		sHandlerExecutor = new HandlerExecutor(sHandler);
		}
		start();
		final Looper looper = getLooper();
		looper.setTraceTag(Trace.TRACE_TAG_SYSTEM_SERVER);
		mHandler = new Handler(looper, /callback=/ null, /* async=/ false, / shared=*/ true);
		mHandlerExecutor = new HandlerExecutor(mHandler);
		}

		public static IoThread get() {
		synchronized (IoThread.class) {
		ensureThreadLocked();
		return sInstance;
		}
		return NoPreloadHolder.sInstance;
		}

		public static Handler getHandler() {
		synchronized (IoThread.class) {
		ensureThreadLocked();
		return sHandler;
		}
		return NoPreloadHolder.sInstance.mHandler;
		}

		public static Executor getExecutor() {
		synchronized (IoThread.class) {
		ensureThreadLocked();
		return sHandlerExecutor;
		}
		return NoPreloadHolder.sInstance.mHandlerExecutor;
		}
		}

services/core/java/com/android/server/PermissionThread.java

+13 −35

Original line number	Diff line number	Diff line
		@@ -21,8 +21,6 @@ import android.os.HandlerExecutor;
		import android.os.Looper;
		import android.os.Trace;

		import com.android.internal.annotations.GuardedBy;

		import java.util.concurrent.Executor;

		/**
		@@ -34,61 +32,41 @@ public final class PermissionThread extends ServiceThread {
		private static final long SLOW_DISPATCH_THRESHOLD_MS = 100;
		private static final long SLOW_DELIVERY_THRESHOLD_MS = 200;

		private static final Object sLock = new Object();
		private static final class NoPreloadHolder {
		private static final PermissionThread sInstance = new PermissionThread();
		}

		@GuardedBy("sLock")
		private static PermissionThread sInstance;
		private static Handler sHandler;
		private static HandlerExecutor sHandlerExecutor;
		private final Handler mHandler;
		private final HandlerExecutor mHandlerExecutor;

		private PermissionThread() {
		super("android.perm", android.os.Process.THREAD_PRIORITY_DEFAULT, /* allowIo= */ true);
		}

		@GuardedBy("sLock")
		private static void ensureThreadLocked() {
		if (sInstance != null) {
		return;
		}

		sInstance = new PermissionThread();
		sInstance.start();
		final Looper looper = sInstance.getLooper();
		start();
		final Looper looper = getLooper();
		looper.setTraceTag(Trace.TRACE_TAG_SYSTEM_SERVER);
		looper.setSlowLogThresholdMs(
		SLOW_DISPATCH_THRESHOLD_MS, SLOW_DELIVERY_THRESHOLD_MS);
		sHandler = new Handler(sInstance.getLooper());
		sHandlerExecutor = new HandlerExecutor(sHandler);
		looper.setSlowLogThresholdMs(SLOW_DISPATCH_THRESHOLD_MS, SLOW_DELIVERY_THRESHOLD_MS);
		mHandler = new Handler(looper);
		mHandlerExecutor = new HandlerExecutor(mHandler);
		}

		/**
		* Obtain a singleton instance of the PermissionThread.
		*/
		public static PermissionThread get() {
		synchronized (sLock) {
		ensureThreadLocked();
		return sInstance;
		}
		return NoPreloadHolder.sInstance;
		}

		/**
		* Obtain a singleton instance of a handler executing in the PermissionThread.
		*/
		public static Handler getHandler() {
		synchronized (sLock) {
		ensureThreadLocked();
		return sHandler;
		}
		return NoPreloadHolder.sInstance.mHandler;
		}


		/**
		* Obtain a singleton instance of an executor of the PermissionThread.
		*/
		public static Executor getExecutor() {
		synchronized (sLock) {
		ensureThreadLocked();
		return sHandlerExecutor;
		}
		return NoPreloadHolder.sInstance.mHandlerExecutor;
		}
		}