AbstractThreadedSyncAdapter.java revision 75d797c2e78d53f49d05b518adb14fd57e0c785c
1/* 2 * Copyright (C) 2009 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 17package android.content; 18 19import android.accounts.Account; 20import android.os.Bundle; 21import android.os.Process; 22 23import java.util.concurrent.atomic.AtomicInteger; 24 25/** 26 * An abstract implementation of a SyncAdapter that spawns a thread to invoke a sync operation. 27 * If a sync operation is already in progress when a startSync() request is received then an error 28 * will be returned to the new request and the existing request will be allowed to continue. 29 * When a startSync() is received and there is no sync operation in progress then a thread 30 * will be started to run the operation and {@link #performSync} will be invoked on that thread. 31 * If a cancelSync() is received that matches an existing sync operation then the thread 32 * that is running that sync operation will be interrupted, which will indicate to the thread 33 * that the sync has been canceled. 34 * 35 * @hide 36 */ 37public abstract class AbstractThreadedSyncAdapter { 38 private final Context mContext; 39 private final AtomicInteger mNumSyncStarts; 40 private final ISyncAdapterImpl mISyncAdapterImpl; 41 42 // all accesses to this member variable must be synchronized on "this" 43 private SyncThread mSyncThread; 44 45 /** Kernel event log tag. Also listed in data/etc/event-log-tags. */ 46 public static final int LOG_SYNC_DETAILS = 2743; 47 private final boolean mAutoInitialize; 48 49 /** 50 * Creates an {@link AbstractThreadedSyncAdapter}. 51 * @param context the {@link android.content.Context} that this is running within. 52 * @param autoInitialize if true then sync requests that have 53 * {@link ContentResolver#SYNC_EXTRAS_INITIALIZE} set will be internally handled by 54 * {@link AbstractThreadedSyncAdapter} by calling 55 * {@link ContentResolver#setIsSyncable(android.accounts.Account, String, int)} with 1 if it 56 * is currently set to <0. 57 */ 58 public AbstractThreadedSyncAdapter(Context context, boolean autoInitialize) { 59 mContext = context; 60 mISyncAdapterImpl = new ISyncAdapterImpl(); 61 mNumSyncStarts = new AtomicInteger(0); 62 mSyncThread = null; 63 mAutoInitialize = autoInitialize; 64 } 65 66 class ISyncAdapterImpl extends ISyncAdapter.Stub { 67 public void startSync(ISyncContext syncContext, String authority, Account account, 68 Bundle extras) { 69 final SyncContext syncContextClient = new SyncContext(syncContext); 70 71 boolean alreadyInProgress; 72 // synchronize to make sure that mSyncThread doesn't change between when we 73 // check it and when we use it 74 synchronized (this) { 75 if (mSyncThread == null) { 76 if (mAutoInitialize 77 && extras != null 78 && extras.getBoolean(ContentResolver.SYNC_EXTRAS_INITIALIZE, false)) { 79 if (ContentResolver.getIsSyncable(account, authority) < 0) { 80 ContentResolver.setIsSyncable(account, authority, 1); 81 } 82 syncContextClient.onFinished(new SyncResult()); 83 return; 84 } 85 mSyncThread = new SyncThread( 86 "SyncAdapterThread-" + mNumSyncStarts.incrementAndGet(), 87 syncContextClient, authority, account, extras); 88 mSyncThread.start(); 89 alreadyInProgress = false; 90 } else { 91 alreadyInProgress = true; 92 } 93 } 94 95 // do this outside since we don't want to call back into the syncContext while 96 // holding the synchronization lock 97 if (alreadyInProgress) { 98 syncContextClient.onFinished(SyncResult.ALREADY_IN_PROGRESS); 99 } 100 } 101 102 public void cancelSync(ISyncContext syncContext) { 103 // synchronize to make sure that mSyncThread doesn't change between when we 104 // check it and when we use it 105 synchronized (this) { 106 if (mSyncThread != null 107 && mSyncThread.mSyncContext.getISyncContext() == syncContext) { 108 mSyncThread.interrupt(); 109 } 110 } 111 } 112 } 113 114 /** 115 * The thread that invokes performSync(). It also acquires the provider for this sync 116 * before calling performSync and releases it afterwards. Cancel this thread in order to 117 * cancel the sync. 118 */ 119 private class SyncThread extends Thread { 120 private final SyncContext mSyncContext; 121 private final String mAuthority; 122 private final Account mAccount; 123 private final Bundle mExtras; 124 125 private SyncThread(String name, SyncContext syncContext, String authority, 126 Account account, Bundle extras) { 127 super(name); 128 mSyncContext = syncContext; 129 mAuthority = authority; 130 mAccount = account; 131 mExtras = extras; 132 } 133 134 public void run() { 135 Process.setThreadPriority(Process.THREAD_PRIORITY_BACKGROUND); 136 137 if (isCanceled()) { 138 return; 139 } 140 141 SyncResult syncResult = new SyncResult(); 142 ContentProviderClient provider = null; 143 try { 144 provider = mContext.getContentResolver().acquireContentProviderClient(mAuthority); 145 if (provider != null) { 146 AbstractThreadedSyncAdapter.this.performSync(mAccount, mExtras, 147 mAuthority, provider, syncResult); 148 } else { 149 // TODO(fredq) update the syncResults to indicate that we were unable to 150 // find the provider. maybe with a ProviderError? 151 } 152 } finally { 153 if (provider != null) { 154 provider.release(); 155 } 156 if (!isCanceled()) { 157 mSyncContext.onFinished(syncResult); 158 } 159 // synchronize so that the assignment will be seen by other threads 160 // that also synchronize accesses to mSyncThread 161 synchronized (this) { 162 mSyncThread = null; 163 } 164 } 165 } 166 167 private boolean isCanceled() { 168 return Thread.currentThread().isInterrupted(); 169 } 170 } 171 172 /** 173 * @return a reference to the ISyncAdapter interface into this SyncAdapter implementation. 174 */ 175 public final ISyncAdapter getISyncAdapter() { 176 return mISyncAdapterImpl; 177 } 178 179 /** 180 * Perform a sync for this account. SyncAdapter-specific parameters may 181 * be specified in extras, which is guaranteed to not be null. Invocations 182 * of this method are guaranteed to be serialized. 183 * 184 * @param account the account that should be synced 185 * @param extras SyncAdapter-specific parameters 186 * @param authority the authority of this sync request 187 * @param provider a ContentProviderClient that points to the ContentProvider for this 188 * authority 189 * @param syncResult SyncAdapter-specific parameters 190 */ 191 public abstract void performSync(Account account, Bundle extras, 192 String authority, ContentProviderClient provider, SyncResult syncResult); 193}