1 /* 2 * Copyright (C) 2013 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package com.android.server; 18 19 import android.os.Handler; 20 import android.os.HandlerExecutor; 21 import android.os.Looper; 22 import android.os.Trace; 23 24 import java.util.concurrent.Executor; 25 26 /** 27 * Shared singleton foreground thread for the system. This is a thread for regular 28 * foreground service operations, which shouldn't be blocked by anything running in 29 * the background. In particular, the shared background thread could be doing 30 * relatively long-running operations like saving state to disk (in addition to 31 * simply being a background priority), which can cause operations scheduled on it 32 * to be delayed for a user-noticeable amount of time. 33 * 34 * @hide 35 */ 36 @android.ravenwood.annotation.RavenwoodKeepWholeClass 37 public final class FgThread extends ServiceThread { 38 private static final long SLOW_DISPATCH_THRESHOLD_MS = 100; 39 private static final long SLOW_DELIVERY_THRESHOLD_MS = 200; 40 41 private static FgThread sInstance; 42 private static Handler sHandler; 43 private static HandlerExecutor sHandlerExecutor; 44 FgThread()45 private FgThread() { 46 super("android.fg", android.os.Process.THREAD_PRIORITY_DEFAULT, true /*allowIo*/); 47 } 48 ensureThreadLocked()49 private static void ensureThreadLocked() { 50 if (sInstance == null) { 51 sInstance = new FgThread(); 52 sInstance.start(); 53 final Looper looper = sInstance.getLooper(); 54 looper.setTraceTag(Trace.TRACE_TAG_SYSTEM_SERVER); 55 looper.setSlowLogThresholdMs( 56 SLOW_DISPATCH_THRESHOLD_MS, SLOW_DELIVERY_THRESHOLD_MS); 57 sHandler = makeSharedHandler(sInstance.getLooper()); 58 sHandlerExecutor = new HandlerExecutor(sHandler); 59 } 60 } 61 get()62 public static FgThread get() { 63 synchronized (FgThread.class) { 64 ensureThreadLocked(); 65 return sInstance; 66 } 67 } 68 getHandler()69 public static Handler getHandler() { 70 synchronized (FgThread.class) { 71 ensureThreadLocked(); 72 return sHandler; 73 } 74 } 75 getExecutor()76 public static Executor getExecutor() { 77 synchronized (FgThread.class) { 78 ensureThreadLocked(); 79 return sHandlerExecutor; 80 } 81 } 82 } 83