1 /* 2 * Copyright (C) 2023 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.healthconnect; 18 19 import android.annotation.NonNull; 20 import android.util.Log; 21 22 import com.android.internal.annotations.GuardedBy; 23 24 import java.util.Map; 25 import java.util.Queue; 26 import java.util.concurrent.ConcurrentSkipListMap; 27 import java.util.concurrent.LinkedBlockingQueue; 28 29 /** 30 * A scheduler class to run the tasks in a Round Robin fashion based on client package names. 31 * 32 * @hide 33 */ 34 public final class HealthConnectRoundRobinScheduler { 35 private static final String TAG = "HealthConnectScheduler"; 36 private final ConcurrentSkipListMap<Integer, Queue<Runnable>> mTasks = 37 new ConcurrentSkipListMap<>(); 38 private final Object mLock = new Object(); 39 40 @GuardedBy("mLock") 41 private boolean mPauseScheduler; 42 43 @GuardedBy("mLock") 44 private Integer mLastKeyUsed; 45 resume()46 void resume() { 47 synchronized (mLock) { 48 mPauseScheduler = false; 49 } 50 } 51 addTask(int uid, Runnable task)52 void addTask(int uid, Runnable task) { 53 synchronized (mLock) { 54 // If the scheduler is currently paused (this can happen if the platform is doing a user 55 // switch), ignore this request. This most likely means that we won't be able to deliver 56 // the result back anyway. 57 if (mPauseScheduler) { 58 Log.e(TAG, "Unable to schedule task for uid: " + uid); 59 return; 60 } 61 62 mTasks.putIfAbsent(uid, new LinkedBlockingQueue<>()); 63 mTasks.get(uid).add(task); 64 } 65 } 66 67 @NonNull getNextTask()68 Runnable getNextTask() { 69 synchronized (mLock) { 70 if (mLastKeyUsed == null) { 71 mLastKeyUsed = mTasks.firstKey(); 72 } 73 74 Map.Entry<Integer, Queue<Runnable>> entry = mTasks.higherEntry(mLastKeyUsed); 75 while (entry != null && entry.getValue().isEmpty()) { 76 mTasks.remove(entry.getKey()); 77 entry = mTasks.higherEntry(entry.getKey()); 78 } 79 80 if (entry == null) { 81 // Reached the end, no tasks found. Reset to first entry and try again. 82 entry = mTasks.firstEntry(); 83 while (entry != null && entry.getValue().isEmpty()) { 84 mTasks.remove(entry.getKey()); 85 entry = mTasks.higherEntry(entry.getKey()); 86 } 87 } 88 89 if (entry != null) { 90 mLastKeyUsed = entry.getKey(); 91 return entry.getValue().poll(); 92 } 93 94 throw new InternalError("Task scheduled but none found"); 95 } 96 } 97 killTasksAndPauseScheduler()98 void killTasksAndPauseScheduler() { 99 synchronized (mLock) { 100 mPauseScheduler = true; 101 mTasks.clear(); 102 } 103 } 104 } 105