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/*
* Copyright (C) 2011 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License
*/
package com.android.providers.contacts;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteTransactionListener;
import android.util.Log;
import com.google.android.collect.Lists;
import com.google.android.collect.Maps;
import java.util.List;
import java.util.Map;
/**
* A transaction for interacting with a Contacts provider. This is used to pass state around
* throughout the operations comprising the transaction, including which databases the overall
* transaction is involved in, and whether the operation being performed is a batch operation.
*/
public class ContactsTransaction {
/**
* Whether this transaction is encompassing a batch of operations. If we're in batch mode,
* transactional operations from non-batch callers are ignored.
*/
private final boolean mBatch;
/**
* The list of databases that have been enlisted in this transaction.
*
* Note we insert elements to the head of the list, so that we endTransaction() in the reverse
* order.
*/
private final List<SQLiteDatabase> mDatabasesForTransaction;
/**
* The mapping of tags to databases involved in this transaction.
*/
private final Map<String, SQLiteDatabase> mDatabaseTagMap;
/**
* Whether any actual changes have been made successfully in this transaction.
*/
private boolean mIsDirty;
/**
* Whether a yield operation failed with an exception. If this occurred, we may not have a
* lock on one of the databases that we started the transaction with (the yield code cleans
* that up itself), so we should do an extra check before ending transactions.
*/
private boolean mYieldFailed;
/**
* Creates a new transaction object, optionally marked as a batch transaction.
* @param batch Whether the transaction is in batch mode.
*/
public ContactsTransaction(boolean batch) {
mBatch = batch;
mDatabasesForTransaction = Lists.newArrayList();
mDatabaseTagMap = Maps.newHashMap();
mIsDirty = false;
}
public boolean isBatch() {
return mBatch;
}
public boolean isDirty() {
return mIsDirty;
}
public void markDirty() {
mIsDirty = true;
}
public void markYieldFailed() {
mYieldFailed = true;
}
/**
* If the given database has not already been enlisted in this transaction, adds it to our
* list of affected databases and starts a transaction on it. If we already have the given
* database in this transaction, this is a no-op.
* @param db The database to start a transaction on, if necessary.
* @param tag A constant that can be used to retrieve the DB instance in this transaction.
* @param listener A transaction listener to attach to this transaction. May be null.
*/
public void startTransactionForDb(SQLiteDatabase db, String tag,
SQLiteTransactionListener listener) {
if (AbstractContactsProvider.ENABLE_TRANSACTION_LOG) {
Log.i(AbstractContactsProvider.TAG, "startTransactionForDb: db=" + db.getPath() +
" tag=" + tag + " listener=" + listener +
" startTransaction=" + !hasDbInTransaction(tag),
new RuntimeException("startTransactionForDb"));
}
if (!hasDbInTransaction(tag)) {
// Insert a new db into the head of the list, so that we'll endTransaction() in
// the reverse order.
mDatabasesForTransaction.add(0, db);
mDatabaseTagMap.put(tag, db);
if (listener != null) {
db.beginTransactionWithListener(listener);
} else {
db.beginTransaction();
}
}
}
/**
* Returns whether DB corresponding to the given tag is currently enlisted in this transaction.
*/
public boolean hasDbInTransaction(String tag) {
return mDatabaseTagMap.containsKey(tag);
}
/**
* Retrieves the database enlisted in the transaction corresponding to the given tag.
* @param tag The tag of the database to look up.
* @return The database corresponding to the tag, or null if no database with that tag has been
* enlisted in this transaction.
*/
public SQLiteDatabase getDbForTag(String tag) {
return mDatabaseTagMap.get(tag);
}
/**
* Removes the database corresponding to the given tag from this transaction. It is now the
* caller's responsibility to do whatever needs to happen with this database - it is no longer
* a part of this transaction.
* @param tag The tag of the database to remove.
* @return The database corresponding to the tag, or null if no database with that tag has been
* enlisted in this transaction.
*/
public SQLiteDatabase removeDbForTag(String tag) {
SQLiteDatabase db = mDatabaseTagMap.get(tag);
mDatabaseTagMap.remove(tag);
mDatabasesForTransaction.remove(db);
return db;
}
/**
* Marks all active DB transactions as successful.
* @param callerIsBatch Whether this is being performed in the context of a batch operation.
* If it is not, and the transaction is marked as batch, this call is a no-op.
*/
public void markSuccessful(boolean callerIsBatch) {
if (!mBatch || callerIsBatch) {
for (SQLiteDatabase db : mDatabasesForTransaction) {
db.setTransactionSuccessful();
}
}
}
/**
* @return the tag for a database. Only intended to be used for logging.
*/
private String getTagForDb(SQLiteDatabase db) {
for (String tag : mDatabaseTagMap.keySet()) {
if (db == mDatabaseTagMap.get(tag)) {
return tag;
}
}
return null;
}
/**
* Completes the transaction, ending the DB transactions for all associated databases.
* @param callerIsBatch Whether this is being performed in the context of a batch operation.
* If it is not, and the transaction is marked as batch, this call is a no-op.
*/
public void finish(boolean callerIsBatch) {
if (AbstractContactsProvider.ENABLE_TRANSACTION_LOG) {
Log.i(AbstractContactsProvider.TAG, "ContactsTransaction.finish callerIsBatch=" +
callerIsBatch, new RuntimeException("ContactsTransaction.finish"));
}
if (!mBatch || callerIsBatch) {
for (SQLiteDatabase db : mDatabasesForTransaction) {
if (AbstractContactsProvider.ENABLE_TRANSACTION_LOG) {
Log.i(AbstractContactsProvider.TAG, "ContactsTransaction.finish: " +
"endTransaction for " + getTagForDb(db));
}
// If an exception was thrown while yielding, it's possible that we no longer have
// a lock on this database, so we need to check before attempting to end its
// transaction. Otherwise, we should always expect to be in a transaction (and will
// throw an exception if this is not the case).
if (mYieldFailed && !db.isDbLockedByCurrentThread()) {
// We no longer hold the lock, so don't do anything with this database.
continue;
}
db.endTransaction();
}
mDatabasesForTransaction.clear();
mDatabaseTagMap.clear();
mIsDirty = false;
}
}
}
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