* Database access is always performed using a session. The session * manages the lifecycle of transactions and database connections. *
* Sessions can be used to perform both read-only and read-write operations. * There is some advantage to knowing when a session is being used for * read-only purposes because the connection pool can optimize the use * of the available connections to permit multiple read-only operations * to execute in parallel whereas read-write operations may need to be serialized. *
* When Write Ahead Logging (WAL) is enabled, the database can * execute simultaneous read-only and read-write transactions, provided that * at most one read-write transaction is performed at a time. When WAL is not * enabled, read-only transactions can execute in parallel but read-write * transactions are mutually exclusive. *
* ** Session objects are not thread-safe. In fact, session objects are thread-bound. * The {@link SQLiteDatabase} uses a thread-local variable to associate a session * with each thread for the use of that thread alone. Consequently, each thread * has its own session object and therefore its own transaction state independent * of other threads. *
* A thread has at most one session per database. This constraint ensures that * a thread can never use more than one database connection at a time for a * given database. As the number of available database connections is limited, * if a single thread tried to acquire multiple connections for the same database * at the same time, it might deadlock. Therefore we allow there to be only * one session (so, at most one connection) per thread per database. *
* ** There are two kinds of transaction: implicit transactions and explicit * transactions. *
* An implicit transaction is created whenever a database operation is requested * and there is no explicit transaction currently in progress. An implicit transaction * only lasts for the duration of the database operation in question and then it * is ended. If the database operation was successful, then its changes are committed. *
* An explicit transaction is started by calling {@link #beginTransaction} and * specifying the desired transaction mode. Once an explicit transaction has begun, * all subsequent database operations will be performed as part of that transaction. * To end an explicit transaction, first call {@link #setTransactionSuccessful} if the * transaction was successful, then call {@link #end}. If the transaction was * marked successful, its changes will be committed, otherwise they will be rolled back. *
* Explicit transactions can also be nested. A nested explicit transaction is * started with {@link #beginTransaction}, marked successful with * {@link #setTransactionSuccessful}and ended with {@link #endTransaction}. * If any nested transaction is not marked successful, then the entire transaction * including all of its nested transactions will be rolled back * when the outermost transaction is ended. *
* To improve concurrency, an explicit transaction can be yielded by calling * {@link #yieldTransaction}. If there is contention for use of the database, * then yielding ends the current transaction, commits its changes, releases the * database connection for use by another session for a little while, and starts a * new transaction with the same properties as the original one. * Changes committed by {@link #yieldTransaction} cannot be rolled back. *
* When a transaction is started, the client can provide a {@link SQLiteTransactionListener} * to listen for notifications of transaction-related events. *
* Recommended usage:
*
* // First, begin the transaction.
* session.beginTransaction(SQLiteSession.TRANSACTION_MODE_DEFERRED, 0);
* try {
* // Then do stuff...
* session.execute("INSERT INTO ...", null, 0);
*
* // As the very last step before ending the transaction, mark it successful.
* session.setTransactionSuccessful();
* } finally {
* // Finally, end the transaction.
* // This statement will commit the transaction if it was marked successful or
* // roll it back otherwise.
* session.endTransaction();
* }
*
* A {@link SQLiteDatabase} can have multiple active sessions at the same * time. Each session acquires and releases connections to the database * as needed to perform each requested database transaction. If all connections * are in use, then database transactions on some sessions will block until a * connection becomes available. *
* The session acquires a single database connection only for the duration * of a single (implicit or explicit) database transaction, then releases it. * This characteristic allows a small pool of database connections to be shared * efficiently by multiple sessions as long as they are not all trying to perform * database transactions at the same time. *
* ** Because there are a limited number of database connections and the session holds * a database connection for the entire duration of a database transaction, * it is important to keep transactions short. This is especially important * for read-write transactions since they may block other transactions * from executing. Consider calling {@link #yieldTransaction} periodically * during long-running transactions. *
* Another important consideration is that transactions that take too long to * run may cause the application UI to become unresponsive. Even if the transaction * is executed in a background thread, the user will get bored and * frustrated if the application shows no data for several seconds while * a transaction runs. *
* Guidelines: *
* This class must tolerate reentrant execution of SQLite operations because * triggers may call custom SQLite functions that perform additional queries. *
* * @hide */ public final class SQLiteSession { private final SQLiteConnectionPool mConnectionPool; private SQLiteConnection mConnection; private int mConnectionFlags; private int mConnectionUseCount; private Transaction mTransactionPool; private Transaction mTransactionStack; /** * Transaction mode: Deferred. *
* In a deferred transaction, no locks are acquired on the database
* until the first operation is performed. If the first operation is
* read-only, then a SHARED lock is acquired, otherwise
* a RESERVED lock is acquired.
*
* While holding a SHARED lock, this session is only allowed to
* read but other sessions are allowed to read or write.
* While holding a RESERVED lock, this session is allowed to read
* or write but other sessions are only allowed to read.
*
* Because the lock is only acquired when needed in a deferred transaction, * it is possible for another session to write to the database first before * this session has a chance to do anything. *
* Corresponds to the SQLite BEGIN DEFERRED transaction mode.
*
* When an immediate transaction begins, the session acquires a
* RESERVED lock.
*
* While holding a RESERVED lock, this session is allowed to read
* or write but other sessions are only allowed to read.
*
* Corresponds to the SQLite BEGIN IMMEDIATE transaction mode.
*
* When an exclusive transaction begins, the session acquires an
* EXCLUSIVE lock.
*
* While holding an EXCLUSIVE lock, this session is allowed to read
* or write but no other sessions are allowed to access the database.
*
* Corresponds to the SQLite BEGIN EXCLUSIVE transaction mode.
*
* Transactions may nest. If the transaction is not in progress, * then a database connection is obtained and a new transaction is started. * Otherwise, a nested transaction is started. *
* Each call to {@link #beginTransaction} must be matched exactly by a call * to {@link #endTransaction}. To mark a transaction as successful, * call {@link #setTransactionSuccessful} before calling {@link #endTransaction}. * If the transaction is not successful, or if any of its nested * transactions were not successful, then the entire transaction will * be rolled back when the outermost transaction is ended. *
* * @param transactionMode The transaction mode. One of: {@link #TRANSACTION_MODE_DEFERRED}, * {@link #TRANSACTION_MODE_IMMEDIATE}, or {@link #TRANSACTION_MODE_EXCLUSIVE}. * Ignored when creating a nested transaction. * @param transactionListener The transaction listener, or null if none. * @param connectionFlags The connection flags to use if a connection must be * acquired by this operation. Refer to {@link SQLiteConnectionPool}. * @param cancellationSignal A signal to cancel the operation in progress, or null if none. * * @throws IllegalStateException if {@link #setTransactionSuccessful} has already been * called for the current transaction. * @throws SQLiteException if an error occurs. * @throws OperationCanceledException if the operation was canceled. * * @see #setTransactionSuccessful * @see #yieldTransaction * @see #endTransaction */ public void beginTransaction(int transactionMode, SQLiteTransactionListener transactionListener, int connectionFlags, CancellationSignal cancellationSignal) { throwIfTransactionMarkedSuccessful(); beginTransactionUnchecked(transactionMode, transactionListener, connectionFlags, cancellationSignal); } private void beginTransactionUnchecked(int transactionMode, SQLiteTransactionListener transactionListener, int connectionFlags, CancellationSignal cancellationSignal) { if (cancellationSignal != null) { cancellationSignal.throwIfCanceled(); } if (mTransactionStack == null) { acquireConnection(null, connectionFlags, cancellationSignal); // might throw } try { // Set up the transaction such that we can back out safely // in case we fail part way. if (mTransactionStack == null) { // Execute SQL might throw a runtime exception. switch (transactionMode) { case TRANSACTION_MODE_IMMEDIATE: mConnection.execute("BEGIN IMMEDIATE;", null, cancellationSignal); // might throw break; case TRANSACTION_MODE_EXCLUSIVE: mConnection.execute("BEGIN EXCLUSIVE;", null, cancellationSignal); // might throw break; default: mConnection.execute("BEGIN;", null, cancellationSignal); // might throw break; } } // Listener might throw a runtime exception. if (transactionListener != null) { try { transactionListener.onBegin(); // might throw } catch (RuntimeException ex) { if (mTransactionStack == null) { mConnection.execute("ROLLBACK;", null, cancellationSignal); // might throw } throw ex; } } // Bookkeeping can't throw, except an OOM, which is just too bad... Transaction transaction = obtainTransaction(transactionMode, transactionListener); transaction.mParent = mTransactionStack; mTransactionStack = transaction; } finally { if (mTransactionStack == null) { releaseConnection(); // might throw } } } /** * Marks the current transaction as having completed successfully. ** This method can be called at most once between {@link #beginTransaction} and * {@link #endTransaction} to indicate that the changes made by the transaction should be * committed. If this method is not called, the changes will be rolled back * when the transaction is ended. *
* * @throws IllegalStateException if there is no current transaction, or if * {@link #setTransactionSuccessful} has already been called for the current transaction. * * @see #beginTransaction * @see #endTransaction */ public void setTransactionSuccessful() { throwIfNoTransaction(); throwIfTransactionMarkedSuccessful(); mTransactionStack.mMarkedSuccessful = true; } /** * Ends the current transaction and commits or rolls back changes. ** If this is the outermost transaction (not nested within any other * transaction), then the changes are committed if {@link #setTransactionSuccessful} * was called or rolled back otherwise. *
* This method must be called exactly once for each call to {@link #beginTransaction}. *
* * @param cancellationSignal A signal to cancel the operation in progress, or null if none. * * @throws IllegalStateException if there is no current transaction. * @throws SQLiteException if an error occurs. * @throws OperationCanceledException if the operation was canceled. * * @see #beginTransaction * @see #setTransactionSuccessful * @see #yieldTransaction */ public void endTransaction(CancellationSignal cancellationSignal) { throwIfNoTransaction(); assert mConnection != null; endTransactionUnchecked(cancellationSignal, false); } private void endTransactionUnchecked(CancellationSignal cancellationSignal, boolean yielding) { if (cancellationSignal != null) { cancellationSignal.throwIfCanceled(); } final Transaction top = mTransactionStack; boolean successful = (top.mMarkedSuccessful || yielding) && !top.mChildFailed; RuntimeException listenerException = null; final SQLiteTransactionListener listener = top.mListener; if (listener != null) { try { if (successful) { listener.onCommit(); // might throw } else { listener.onRollback(); // might throw } } catch (RuntimeException ex) { listenerException = ex; successful = false; } } mTransactionStack = top.mParent; recycleTransaction(top); if (mTransactionStack != null) { if (!successful) { mTransactionStack.mChildFailed = true; } } else { try { if (successful) { mConnection.execute("COMMIT;", null, cancellationSignal); // might throw } else { mConnection.execute("ROLLBACK;", null, cancellationSignal); // might throw } } finally { releaseConnection(); // might throw } } if (listenerException != null) { throw listenerException; } } /** * Temporarily ends a transaction to let other threads have use of * the database. Begins a new transaction after a specified delay. ** If there are other threads waiting to acquire connections, * then the current transaction is committed and the database * connection is released. After a short delay, a new transaction * is started. *
* The transaction is assumed to be successful so far. Do not call * {@link #setTransactionSuccessful()} before calling this method. * This method will fail if the transaction has already been marked * successful. *
* The changes that were committed by a yield cannot be rolled back later. *
* Before this method was called, there must already have been * a transaction in progress. When this method returns, there will * still be a transaction in progress, either the same one as before * or a new one if the transaction was actually yielded. *
* This method should not be called when there is a nested transaction
* in progress because it is not possible to yield a nested transaction.
* If throwIfNested is true, then attempting to yield
* a nested transaction will throw {@link IllegalStateException}, otherwise
* the method will return false in that case.
*
* If there is no nested transaction in progress but a previous nested
* transaction failed, then the transaction is not yielded (because it
* must be rolled back) and this method returns false.
*
throwIfNested is true and
* there is no current transaction, there is a nested transaction in progress or
* if {@link #setTransactionSuccessful} has already been called for the current transaction.
* @throws SQLiteException if an error occurs.
* @throws OperationCanceledException if the operation was canceled.
*
* @see #beginTransaction
* @see #endTransaction
*/
public boolean yieldTransaction(long sleepAfterYieldDelayMillis, boolean throwIfUnsafe,
CancellationSignal cancellationSignal) {
if (throwIfUnsafe) {
throwIfNoTransaction();
throwIfTransactionMarkedSuccessful();
throwIfNestedTransaction();
} else {
if (mTransactionStack == null || mTransactionStack.mMarkedSuccessful
|| mTransactionStack.mParent != null) {
return false;
}
}
assert mConnection != null;
if (mTransactionStack.mChildFailed) {
return false;
}
return yieldTransactionUnchecked(sleepAfterYieldDelayMillis,
cancellationSignal); // might throw
}
private boolean yieldTransactionUnchecked(long sleepAfterYieldDelayMillis,
CancellationSignal cancellationSignal) {
if (cancellationSignal != null) {
cancellationSignal.throwIfCanceled();
}
if (!mConnectionPool.shouldYieldConnection(mConnection, mConnectionFlags)) {
return false;
}
final int transactionMode = mTransactionStack.mMode;
final SQLiteTransactionListener listener = mTransactionStack.mListener;
final int connectionFlags = mConnectionFlags;
endTransactionUnchecked(cancellationSignal, true); // might throw
if (sleepAfterYieldDelayMillis > 0) {
try {
Thread.sleep(sleepAfterYieldDelayMillis);
} catch (InterruptedException ex) {
// we have been interrupted, that's all we need to do
}
}
beginTransactionUnchecked(transactionMode, listener, connectionFlags,
cancellationSignal); // might throw
return true;
}
/**
* Prepares a statement for execution but does not bind its parameters or execute it.
* * This method can be used to check for syntax errors during compilation * prior to execution of the statement. If the {@code outStatementInfo} argument * is not null, the provided {@link SQLiteStatementInfo} object is populated * with information about the statement. *
* A prepared statement makes no reference to the arguments that may eventually * be bound to it, consequently it it possible to cache certain prepared statements * such as SELECT or INSERT/UPDATE statements. If the statement is cacheable, * then it will be stored in the cache for later and reused if possible. *
* * @param sql The SQL statement to prepare. * @param connectionFlags The connection flags to use if a connection must be * acquired by this operation. Refer to {@link SQLiteConnectionPool}. * @param cancellationSignal A signal to cancel the operation in progress, or null if none. * @param outStatementInfo The {@link SQLiteStatementInfo} object to populate * with information about the statement, or null if none. * * @throws SQLiteException if an error occurs, such as a syntax error. * @throws OperationCanceledException if the operation was canceled. */ public void prepare(String sql, int connectionFlags, CancellationSignal cancellationSignal, SQLiteStatementInfo outStatementInfo) { if (sql == null) { throw new IllegalArgumentException("sql must not be null."); } if (cancellationSignal != null) { cancellationSignal.throwIfCanceled(); } acquireConnection(sql, connectionFlags, cancellationSignal); // might throw try { mConnection.prepare(sql, outStatementInfo); // might throw } finally { releaseConnection(); // might throw } } /** * Executes a statement that does not return a result. * * @param sql The SQL statement to execute. * @param bindArgs The arguments to bind, or null if none. * @param connectionFlags The connection flags to use if a connection must be * acquired by this operation. Refer to {@link SQLiteConnectionPool}. * @param cancellationSignal A signal to cancel the operation in progress, or null if none. * * @throws SQLiteException if an error occurs, such as a syntax error * or invalid number of bind arguments. * @throws OperationCanceledException if the operation was canceled. */ public void execute(String sql, Object[] bindArgs, int connectionFlags, CancellationSignal cancellationSignal) { if (sql == null) { throw new IllegalArgumentException("sql must not be null."); } if (executeSpecial(sql, bindArgs, connectionFlags, cancellationSignal)) { return; } acquireConnection(sql, connectionFlags, cancellationSignal); // might throw try { mConnection.execute(sql, bindArgs, cancellationSignal); // might throw } finally { releaseConnection(); // might throw } } /** * Executes a statement that returns a singlelong result.
*
* @param sql The SQL statement to execute.
* @param bindArgs The arguments to bind, or null if none.
* @param connectionFlags The connection flags to use if a connection must be
* acquired by this operation. Refer to {@link SQLiteConnectionPool}.
* @param cancellationSignal A signal to cancel the operation in progress, or null if none.
* @return The value of the first column in the first row of the result set
* as a long, or zero if none.
*
* @throws SQLiteException if an error occurs, such as a syntax error
* or invalid number of bind arguments.
* @throws OperationCanceledException if the operation was canceled.
*/
public long executeForLong(String sql, Object[] bindArgs, int connectionFlags,
CancellationSignal cancellationSignal) {
if (sql == null) {
throw new IllegalArgumentException("sql must not be null.");
}
if (executeSpecial(sql, bindArgs, connectionFlags, cancellationSignal)) {
return 0;
}
acquireConnection(sql, connectionFlags, cancellationSignal); // might throw
try {
return mConnection.executeForLong(sql, bindArgs, cancellationSignal); // might throw
} finally {
releaseConnection(); // might throw
}
}
/**
* Executes a statement that returns a single {@link String} result.
*
* @param sql The SQL statement to execute.
* @param bindArgs The arguments to bind, or null if none.
* @param connectionFlags The connection flags to use if a connection must be
* acquired by this operation. Refer to {@link SQLiteConnectionPool}.
* @param cancellationSignal A signal to cancel the operation in progress, or null if none.
* @return The value of the first column in the first row of the result set
* as a String, or null if none.
*
* @throws SQLiteException if an error occurs, such as a syntax error
* or invalid number of bind arguments.
* @throws OperationCanceledException if the operation was canceled.
*/
public String executeForString(String sql, Object[] bindArgs, int connectionFlags,
CancellationSignal cancellationSignal) {
if (sql == null) {
throw new IllegalArgumentException("sql must not be null.");
}
if (executeSpecial(sql, bindArgs, connectionFlags, cancellationSignal)) {
return null;
}
acquireConnection(sql, connectionFlags, cancellationSignal); // might throw
try {
return mConnection.executeForString(sql, bindArgs, cancellationSignal); // might throw
} finally {
releaseConnection(); // might throw
}
}
/**
* Executes a statement that returns a single BLOB result as a
* file descriptor to a shared memory region.
*
* @param sql The SQL statement to execute.
* @param bindArgs The arguments to bind, or null if none.
* @param connectionFlags The connection flags to use if a connection must be
* acquired by this operation. Refer to {@link SQLiteConnectionPool}.
* @param cancellationSignal A signal to cancel the operation in progress, or null if none.
* @return The file descriptor for a shared memory region that contains
* the value of the first column in the first row of the result set as a BLOB,
* or null if none.
*
* @throws SQLiteException if an error occurs, such as a syntax error
* or invalid number of bind arguments.
* @throws OperationCanceledException if the operation was canceled.
*/
public ParcelFileDescriptor executeForBlobFileDescriptor(String sql, Object[] bindArgs,
int connectionFlags, CancellationSignal cancellationSignal) {
if (sql == null) {
throw new IllegalArgumentException("sql must not be null.");
}
if (executeSpecial(sql, bindArgs, connectionFlags, cancellationSignal)) {
return null;
}
acquireConnection(sql, connectionFlags, cancellationSignal); // might throw
try {
return mConnection.executeForBlobFileDescriptor(sql, bindArgs,
cancellationSignal); // might throw
} finally {
releaseConnection(); // might throw
}
}
/**
* Executes a statement that returns a count of the number of rows
* that were changed. Use for UPDATE or DELETE SQL statements.
*
* @param sql The SQL statement to execute.
* @param bindArgs The arguments to bind, or null if none.
* @param connectionFlags The connection flags to use if a connection must be
* acquired by this operation. Refer to {@link SQLiteConnectionPool}.
* @param cancellationSignal A signal to cancel the operation in progress, or null if none.
* @return The number of rows that were changed.
*
* @throws SQLiteException if an error occurs, such as a syntax error
* or invalid number of bind arguments.
* @throws OperationCanceledException if the operation was canceled.
*/
public int executeForChangedRowCount(String sql, Object[] bindArgs, int connectionFlags,
CancellationSignal cancellationSignal) {
if (sql == null) {
throw new IllegalArgumentException("sql must not be null.");
}
if (executeSpecial(sql, bindArgs, connectionFlags, cancellationSignal)) {
return 0;
}
acquireConnection(sql, connectionFlags, cancellationSignal); // might throw
try {
return mConnection.executeForChangedRowCount(sql, bindArgs,
cancellationSignal); // might throw
} finally {
releaseConnection(); // might throw
}
}
/**
* Executes a statement that returns the row id of the last row inserted
* by the statement. Use for INSERT SQL statements.
*
* @param sql The SQL statement to execute.
* @param bindArgs The arguments to bind, or null if none.
* @param connectionFlags The connection flags to use if a connection must be
* acquired by this operation. Refer to {@link SQLiteConnectionPool}.
* @param cancellationSignal A signal to cancel the operation in progress, or null if none.
* @return The row id of the last row that was inserted, or 0 if none.
*
* @throws SQLiteException if an error occurs, such as a syntax error
* or invalid number of bind arguments.
* @throws OperationCanceledException if the operation was canceled.
*/
public long executeForLastInsertedRowId(String sql, Object[] bindArgs, int connectionFlags,
CancellationSignal cancellationSignal) {
if (sql == null) {
throw new IllegalArgumentException("sql must not be null.");
}
if (executeSpecial(sql, bindArgs, connectionFlags, cancellationSignal)) {
return 0;
}
acquireConnection(sql, connectionFlags, cancellationSignal); // might throw
try {
return mConnection.executeForLastInsertedRowId(sql, bindArgs,
cancellationSignal); // might throw
} finally {
releaseConnection(); // might throw
}
}
/**
* Executes a statement and populates the specified {@link CursorWindow}
* with a range of results. Returns the number of rows that were counted
* during query execution.
*
* @param sql The SQL statement to execute.
* @param bindArgs The arguments to bind, or null if none.
* @param window The cursor window to clear and fill.
* @param startPos The start position for filling the window.
* @param requiredPos The position of a row that MUST be in the window.
* If it won't fit, then the query should discard part of what it filled
* so that it does. Must be greater than or equal to startPos.
* @param countAllRows True to count all rows that the query would return
* regagless of whether they fit in the window.
* @param connectionFlags The connection flags to use if a connection must be
* acquired by this operation. Refer to {@link SQLiteConnectionPool}.
* @param cancellationSignal A signal to cancel the operation in progress, or null if none.
* @return The number of rows that were counted during query execution. Might
* not be all rows in the result set unless countAllRows is true.
*
* @throws SQLiteException if an error occurs, such as a syntax error
* or invalid number of bind arguments.
* @throws OperationCanceledException if the operation was canceled.
*/
public int executeForCursorWindow(String sql, Object[] bindArgs,
CursorWindow window, int startPos, int requiredPos, boolean countAllRows,
int connectionFlags, CancellationSignal cancellationSignal) {
if (sql == null) {
throw new IllegalArgumentException("sql must not be null.");
}
if (window == null) {
throw new IllegalArgumentException("window must not be null.");
}
if (executeSpecial(sql, bindArgs, connectionFlags, cancellationSignal)) {
window.clear();
return 0;
}
acquireConnection(sql, connectionFlags, cancellationSignal); // might throw
try {
return mConnection.executeForCursorWindow(sql, bindArgs,
window, startPos, requiredPos, countAllRows,
cancellationSignal); // might throw
} finally {
releaseConnection(); // might throw
}
}
/**
* Performs special reinterpretation of certain SQL statements such as "BEGIN",
* "COMMIT" and "ROLLBACK" to ensure that transaction state invariants are
* maintained.
*
* This function is mainly used to support legacy apps that perform their
* own transactions by executing raw SQL rather than calling {@link #beginTransaction}
* and the like.
*
* @param sql The SQL statement to execute.
* @param bindArgs The arguments to bind, or null if none.
* @param connectionFlags The connection flags to use if a connection must be
* acquired by this operation. Refer to {@link SQLiteConnectionPool}.
* @param cancellationSignal A signal to cancel the operation in progress, or null if none.
* @return True if the statement was of a special form that was handled here,
* false otherwise.
*
* @throws SQLiteException if an error occurs, such as a syntax error
* or invalid number of bind arguments.
* @throws OperationCanceledException if the operation was canceled.
*/
private boolean executeSpecial(String sql, Object[] bindArgs, int connectionFlags,
CancellationSignal cancellationSignal) {
if (cancellationSignal != null) {
cancellationSignal.throwIfCanceled();
}
final int type = DatabaseUtils.getSqlStatementType(sql);
switch (type) {
case DatabaseUtils.STATEMENT_BEGIN:
beginTransaction(TRANSACTION_MODE_EXCLUSIVE, null, connectionFlags,
cancellationSignal);
return true;
case DatabaseUtils.STATEMENT_COMMIT:
setTransactionSuccessful();
endTransaction(cancellationSignal);
return true;
case DatabaseUtils.STATEMENT_ABORT:
endTransaction(cancellationSignal);
return true;
}
return false;
}
private void acquireConnection(String sql, int connectionFlags,
CancellationSignal cancellationSignal) {
if (mConnection == null) {
assert mConnectionUseCount == 0;
mConnection = mConnectionPool.acquireConnection(sql, connectionFlags,
cancellationSignal); // might throw
mConnectionFlags = connectionFlags;
}
mConnectionUseCount += 1;
}
private void releaseConnection() {
assert mConnection != null;
assert mConnectionUseCount > 0;
if (--mConnectionUseCount == 0) {
try {
mConnectionPool.releaseConnection(mConnection); // might throw
} finally {
mConnection = null;
}
}
}
private void throwIfNoTransaction() {
if (mTransactionStack == null) {
throw new IllegalStateException("Cannot perform this operation because "
+ "there is no current transaction.");
}
}
private void throwIfTransactionMarkedSuccessful() {
if (mTransactionStack != null && mTransactionStack.mMarkedSuccessful) {
throw new IllegalStateException("Cannot perform this operation because "
+ "the transaction has already been marked successful. The only "
+ "thing you can do now is call endTransaction().");
}
}
private void throwIfNestedTransaction() {
if (hasNestedTransaction()) {
throw new IllegalStateException("Cannot perform this operation because "
+ "a nested transaction is in progress.");
}
}
private Transaction obtainTransaction(int mode, SQLiteTransactionListener listener) {
Transaction transaction = mTransactionPool;
if (transaction != null) {
mTransactionPool = transaction.mParent;
transaction.mParent = null;
transaction.mMarkedSuccessful = false;
transaction.mChildFailed = false;
} else {
transaction = new Transaction();
}
transaction.mMode = mode;
transaction.mListener = listener;
return transaction;
}
private void recycleTransaction(Transaction transaction) {
transaction.mParent = mTransactionPool;
transaction.mListener = null;
mTransactionPool = transaction;
}
private static final class Transaction {
public Transaction mParent;
public int mMode;
public SQLiteTransactionListener mListener;
public boolean mMarkedSuccessful;
public boolean mChildFailed;
}
}