AbstractThreadedSyncAdapter.java revision 3cff76aaa893049d02467a231d477e86a0f80daa
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 mSyncThreadLock 43 private SyncThread mSyncThread; 44 private final Object mSyncThreadLock = new Object(); 45 46 /** Kernel event log tag. Also listed in data/etc/event-log-tags. */ 47 public static final int LOG_SYNC_DETAILS = 2743; 48 private final boolean mAutoInitialize; 49 50 /** 51 * Creates an {@link AbstractThreadedSyncAdapter}. 52 * @param context the {@link android.content.Context} that this is running within. 53 * @param autoInitialize if true then sync requests that have 54 * {@link ContentResolver#SYNC_EXTRAS_INITIALIZE} set will be internally handled by 55 * {@link AbstractThreadedSyncAdapter} by calling 56 * {@link ContentResolver#setIsSyncable(android.accounts.Account, String, int)} with 1 if it 57 * is currently set to <0. 58 */ 59 public AbstractThreadedSyncAdapter(Context context, boolean autoInitialize) { 60 mContext = context; 61 mISyncAdapterImpl = new ISyncAdapterImpl(); 62 mNumSyncStarts = new AtomicInteger(0); 63 mSyncThread = null; 64 mAutoInitialize = autoInitialize; 65 } 66 67 class ISyncAdapterImpl extends ISyncAdapter.Stub { 68 public void startSync(ISyncContext syncContext, String authority, Account account, 69 Bundle extras) { 70 final SyncContext syncContextClient = new SyncContext(syncContext); 71 72 boolean alreadyInProgress; 73 // synchronize to make sure that mSyncThread doesn't change between when we 74 // check it and when we use it 75 synchronized (mSyncThreadLock) { 76 if (mSyncThread == null) { 77 if (mAutoInitialize 78 && extras != null 79 && extras.getBoolean(ContentResolver.SYNC_EXTRAS_INITIALIZE, false)) { 80 if (ContentResolver.getIsSyncable(account, authority) < 0) { 81 ContentResolver.setIsSyncable(account, authority, 1); 82 } 83 syncContextClient.onFinished(new SyncResult()); 84 return; 85 } 86 mSyncThread = new SyncThread( 87 "SyncAdapterThread-" + mNumSyncStarts.incrementAndGet(), 88 syncContextClient, authority, account, extras); 89 mSyncThread.start(); 90 alreadyInProgress = false; 91 } else { 92 alreadyInProgress = true; 93 } 94 } 95 96 // do this outside since we don't want to call back into the syncContext while 97 // holding the synchronization lock 98 if (alreadyInProgress) { 99 syncContextClient.onFinished(SyncResult.ALREADY_IN_PROGRESS); 100 } 101 } 102 103 public void cancelSync(ISyncContext syncContext) { 104 // synchronize to make sure that mSyncThread doesn't change between when we 105 // check it and when we use it 106 synchronized (mSyncThreadLock) { 107 if (mSyncThread != null 108 && mSyncThread.mSyncContext.getISyncContext() == syncContext) { 109 mSyncThread.interrupt(); 110 } 111 } 112 } 113 } 114 115 /** 116 * The thread that invokes performSync(). It also acquires the provider for this sync 117 * before calling performSync and releases it afterwards. Cancel this thread in order to 118 * cancel the sync. 119 */ 120 private class SyncThread extends Thread { 121 private final SyncContext mSyncContext; 122 private final String mAuthority; 123 private final Account mAccount; 124 private final Bundle mExtras; 125 126 private SyncThread(String name, SyncContext syncContext, String authority, 127 Account account, Bundle extras) { 128 super(name); 129 mSyncContext = syncContext; 130 mAuthority = authority; 131 mAccount = account; 132 mExtras = extras; 133 } 134 135 public void run() { 136 Process.setThreadPriority(Process.THREAD_PRIORITY_BACKGROUND); 137 138 if (isCanceled()) { 139 return; 140 } 141 142 SyncResult syncResult = new SyncResult(); 143 ContentProviderClient provider = null; 144 try { 145 provider = mContext.getContentResolver().acquireContentProviderClient(mAuthority); 146 if (provider != null) { 147 AbstractThreadedSyncAdapter.this.performSync(mAccount, mExtras, 148 mAuthority, provider, syncResult); 149 } else { 150 // TODO(fredq) update the syncResults to indicate that we were unable to 151 // find the provider. maybe with a ProviderError? 152 } 153 } finally { 154 if (provider != null) { 155 provider.release(); 156 } 157 if (!isCanceled()) { 158 mSyncContext.onFinished(syncResult); 159 } 160 // synchronize so that the assignment will be seen by other threads 161 // that also synchronize accesses to mSyncThread 162 synchronized (mSyncThreadLock) { 163 mSyncThread = null; 164 } 165 } 166 } 167 168 private boolean isCanceled() { 169 return Thread.currentThread().isInterrupted(); 170 } 171 } 172 173 /** 174 * @return a reference to the ISyncAdapter interface into this SyncAdapter implementation. 175 */ 176 public final ISyncAdapter getISyncAdapter() { 177 return mISyncAdapterImpl; 178 } 179 180 /** 181 * Perform a sync for this account. SyncAdapter-specific parameters may 182 * be specified in extras, which is guaranteed to not be null. Invocations 183 * of this method are guaranteed to be serialized. 184 * 185 * @param account the account that should be synced 186 * @param extras SyncAdapter-specific parameters 187 * @param authority the authority of this sync request 188 * @param provider a ContentProviderClient that points to the ContentProvider for this 189 * authority 190 * @param syncResult SyncAdapter-specific parameters 191 */ 192 public abstract void performSync(Account account, Bundle extras, 193 String authority, ContentProviderClient provider, SyncResult syncResult); 194}