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.Looper; 21 import android.os.Trace; 22 23 /** 24 * Shared singleton foreground thread for the system. This is a thread for regular 25 * foreground service operations, which shouldn't be blocked by anything running in 26 * the background. In particular, the shared background thread could be doing 27 * relatively long-running operations like saving state to disk (in addition to 28 * simply being a background priority), which can cause operations scheduled on it 29 * to be delayed for a user-noticeable amount of time. 30 */ 31 public final class FgThread extends ServiceThread { 32 private static final long SLOW_DISPATCH_THRESHOLD_MS = 100; 33 private static final long SLOW_DELIVERY_THRESHOLD_MS = 200; 34 35 private static FgThread sInstance; 36 private static Handler sHandler; 37 38 private FgThread() { 39 super("android.fg", android.os.Process.THREAD_PRIORITY_DEFAULT, true /*allowIo*/); 40 } 41 42 private static void ensureThreadLocked() { 43 if (sInstance == null) { 44 sInstance = new FgThread(); 45 sInstance.start(); 46 final Looper looper = sInstance.getLooper(); 47 looper.setTraceTag(Trace.TRACE_TAG_SYSTEM_SERVER); 48 looper.setSlowLogThresholdMs( 49 SLOW_DISPATCH_THRESHOLD_MS, SLOW_DELIVERY_THRESHOLD_MS); 50 sHandler = new Handler(sInstance.getLooper()); 51 } 52 } 53 54 public static FgThread get() { 55 synchronized (FgThread.class) { 56 ensureThreadLocked(); 57 return sInstance; 58 } 59 } 60 61 public static Handler getHandler() { 62 synchronized (FgThread.class) { 63 ensureThreadLocked(); 64 return sHandler; 65 } 66 } 67 } 68
