/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- * vim: sw=2 ts=2 et lcs=trail\:.,tab\:>~ : * This Source Code Form is subject to the terms of the Mozilla Public * License, v. 2.0. If a copy of the MPL was not distributed with this * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ #include "nsAutoPtr.h" #include "sqlite3.h" #include "mozIStorageStatementCallback.h" #include "mozStorageBindingParams.h" #include "mozStorageHelper.h" #include "mozStorageResultSet.h" #include "mozStorageRow.h" #include "mozStorageConnection.h" #include "mozStorageError.h" #include "mozStoragePrivateHelpers.h" #include "mozStorageStatementData.h" #include "mozStorageAsyncStatementExecution.h" #include "mozilla/DebugOnly.h" #include "mozilla/Telemetry.h" namespace mozilla { namespace storage { /** * The following constants help batch rows into result sets. * MAX_MILLISECONDS_BETWEEN_RESULTS was chosen because any user-based task that * takes less than 200 milliseconds is considered to feel instantaneous to end * users. MAX_ROWS_PER_RESULT was arbitrarily chosen to reduce the number of * dispatches to calling thread, while also providing reasonably-sized sets of * data for consumers. Both of these constants are used because we assume that * consumers are trying to avoid blocking their execution thread for long * periods of time, and dispatching many small events to the calling thread will * end up blocking it. */ #define MAX_MILLISECONDS_BETWEEN_RESULTS 75 #define MAX_ROWS_PER_RESULT 15 //////////////////////////////////////////////////////////////////////////////// //// AsyncExecuteStatements /* static */ nsresult AsyncExecuteStatements::execute(StatementDataArray &aStatements, Connection *aConnection, sqlite3 *aNativeConnection, mozIStorageStatementCallback *aCallback, mozIStoragePendingStatement **_stmt) { // Create our event to run in the background RefPtr<AsyncExecuteStatements> event = new AsyncExecuteStatements(aStatements, aConnection, aNativeConnection, aCallback); NS_ENSURE_TRUE(event, NS_ERROR_OUT_OF_MEMORY); // Dispatch it to the background nsIEventTarget *target = aConnection->getAsyncExecutionTarget(); // If we don't have a valid target, this is a bug somewhere else. In the past, // this assert found cases where a Run method would schedule a new statement // without checking if asyncClose had been called. The caller must prevent // that from happening or, if the work is not critical, just avoid creating // the new statement during shutdown. See bug 718449 for an example. MOZ_ASSERT(target); if (!target) { return NS_ERROR_NOT_AVAILABLE; } nsresult rv = target->Dispatch(event, NS_DISPATCH_NORMAL); NS_ENSURE_SUCCESS(rv, rv); // Return it as the pending statement object and track it. event.forget(_stmt); return NS_OK; } AsyncExecuteStatements::AsyncExecuteStatements(StatementDataArray &aStatements, Connection *aConnection, sqlite3 *aNativeConnection, mozIStorageStatementCallback *aCallback) : mConnection(aConnection) , mNativeConnection(aNativeConnection) , mHasTransaction(false) , mCallback(aCallback) , mCallingThread(::do_GetCurrentThread()) , mMaxWait(TimeDuration::FromMilliseconds(MAX_MILLISECONDS_BETWEEN_RESULTS)) , mIntervalStart(TimeStamp::Now()) , mState(PENDING) , mCancelRequested(false) , mMutex(aConnection->sharedAsyncExecutionMutex) , mDBMutex(aConnection->sharedDBMutex) , mRequestStartDate(TimeStamp::Now()) { (void)mStatements.SwapElements(aStatements); NS_ASSERTION(mStatements.Length(), "We weren't given any statements!"); } AsyncExecuteStatements::~AsyncExecuteStatements() { MOZ_ASSERT(!mCallback, "Never called the Completion callback!"); MOZ_ASSERT(!mHasTransaction, "There should be no transaction at this point"); if (mCallback) { NS_ProxyRelease(mCallingThread, mCallback.forget()); } } bool AsyncExecuteStatements::shouldNotify() { #ifdef DEBUG mMutex.AssertNotCurrentThreadOwns(); bool onCallingThread = false; (void)mCallingThread->IsOnCurrentThread(&onCallingThread); NS_ASSERTION(onCallingThread, "runEvent not running on the calling thread!"); #endif // We do not need to acquire mMutex here because it can only ever be written // to on the calling thread, and the only thread that can call us is the // calling thread, so we know that our access is serialized. return !mCancelRequested; } bool AsyncExecuteStatements::bindExecuteAndProcessStatement(StatementData &aData, bool aLastStatement) { mMutex.AssertNotCurrentThreadOwns(); sqlite3_stmt *aStatement = nullptr; // This cannot fail; we are only called if it's available. (void)aData.getSqliteStatement(&aStatement); NS_ASSERTION(aStatement, "You broke the code; do not call here like that!"); BindingParamsArray *paramsArray(aData); // Iterate through all of our parameters, bind them, and execute. bool continueProcessing = true; BindingParamsArray::iterator itr = paramsArray->begin(); BindingParamsArray::iterator end = paramsArray->end(); while (itr != end && continueProcessing) { // Bind the data to our statement. nsCOMPtr<IStorageBindingParamsInternal> bindingInternal = do_QueryInterface(*itr); nsCOMPtr<mozIStorageError> error = bindingInternal->bind(aStatement); if (error) { // Set our error state. mState = ERROR; // And notify. (void)notifyError(error); return false; } // Advance our iterator, execute, and then process the statement. itr++; bool lastStatement = aLastStatement && itr == end; continueProcessing = executeAndProcessStatement(aStatement, lastStatement); // Always reset our statement. (void)::sqlite3_reset(aStatement); } return continueProcessing; } bool AsyncExecuteStatements::executeAndProcessStatement(sqlite3_stmt *aStatement, bool aLastStatement) { mMutex.AssertNotCurrentThreadOwns(); // Execute our statement bool hasResults; do { hasResults = executeStatement(aStatement); // If we had an error, bail. if (mState == ERROR) return false; // If we have been canceled, there is no point in going on... { MutexAutoLock lockedScope(mMutex); if (mCancelRequested) { mState = CANCELED; return false; } } // Build our result set and notify if we got anything back and have a // callback to notify. if (mCallback && hasResults && NS_FAILED(buildAndNotifyResults(aStatement))) { // We had an error notifying, so we notify on error and stop processing. mState = ERROR; // Notify, and stop processing statements. (void)notifyError(mozIStorageError::ERROR, "An error occurred while notifying about results"); return false; } } while (hasResults); #ifndef MOZ_STORAGE_SORTWARNING_SQL_DUMP if (MOZ_LOG_TEST(gStorageLog, LogLevel::Warning)) #endif { // Check to make sure that this statement was smart about what it did. checkAndLogStatementPerformance(aStatement); } // If we are done, we need to set our state accordingly while we still hold // our mutex. We would have already returned if we were canceled or had // an error at this point. if (aLastStatement) mState = COMPLETED; return true; } bool AsyncExecuteStatements::executeStatement(sqlite3_stmt *aStatement) { mMutex.AssertNotCurrentThreadOwns(); while (true) { // lock the sqlite mutex so sqlite3_errmsg cannot change SQLiteMutexAutoLock lockedScope(mDBMutex); int rc = mConnection->stepStatement(mNativeConnection, aStatement); // Stop if we have no more results. if (rc == SQLITE_DONE) { return false; } // If we got results, we can return now. if (rc == SQLITE_ROW) { return true; } // Some errors are not fatal, and we can handle them and continue. if (rc == SQLITE_BUSY) { // Don't hold the lock while we call outside our module. SQLiteMutexAutoUnlock unlockedScope(mDBMutex); // Yield, and try again (void)::PR_Sleep(PR_INTERVAL_NO_WAIT); continue; } // Set an error state. mState = ERROR; // Construct the error message before giving up the mutex (which we cannot // hold during the call to notifyError). nsCOMPtr<mozIStorageError> errorObj( new Error(rc, ::sqlite3_errmsg(mNativeConnection)) ); // We cannot hold the DB mutex while calling notifyError. SQLiteMutexAutoUnlock unlockedScope(mDBMutex); (void)notifyError(errorObj); // Finally, indicate that we should stop processing. return false; } } nsresult AsyncExecuteStatements::buildAndNotifyResults(sqlite3_stmt *aStatement) { NS_ASSERTION(mCallback, "Trying to dispatch results without a callback!"); mMutex.AssertNotCurrentThreadOwns(); // Build result object if we need it. if (!mResultSet) mResultSet = new ResultSet(); NS_ENSURE_TRUE(mResultSet, NS_ERROR_OUT_OF_MEMORY); RefPtr<Row> row(new Row()); NS_ENSURE_TRUE(row, NS_ERROR_OUT_OF_MEMORY); nsresult rv = row->initialize(aStatement); NS_ENSURE_SUCCESS(rv, rv); rv = mResultSet->add(row); NS_ENSURE_SUCCESS(rv, rv); // If we have hit our maximum number of allowed results, or if we have hit // the maximum amount of time we want to wait for results, notify the // calling thread about it. TimeStamp now = TimeStamp::Now(); TimeDuration delta = now - mIntervalStart; if (mResultSet->rows() >= MAX_ROWS_PER_RESULT || delta > mMaxWait) { // Notify the caller rv = notifyResults(); if (NS_FAILED(rv)) return NS_OK; // we'll try again with the next result // Reset our start time mIntervalStart = now; } return NS_OK; } nsresult AsyncExecuteStatements::notifyComplete() { mMutex.AssertNotCurrentThreadOwns(); NS_ASSERTION(mState != PENDING, "Still in a pending state when calling Complete!"); // Reset our statements before we try to commit or rollback. If we are // canceling and have statements that think they have pending work, the // rollback will fail. for (uint32_t i = 0; i < mStatements.Length(); i++) mStatements[i].reset(); // Release references to the statement data as soon as possible. If this // is the last reference, statements will be finalized immediately on the // async thread, hence avoiding several bounces between threads and possible // race conditions with AsyncClose(). mStatements.Clear(); // Handle our transaction, if we have one if (mHasTransaction) { if (mState == COMPLETED) { nsresult rv = mConnection->commitTransactionInternal(mNativeConnection); if (NS_FAILED(rv)) { mState = ERROR; (void)notifyError(mozIStorageError::ERROR, "Transaction failed to commit"); } } else { DebugOnly<nsresult> rv = mConnection->rollbackTransactionInternal(mNativeConnection); NS_WARNING_ASSERTION(NS_SUCCEEDED(rv), "Transaction failed to rollback"); } mHasTransaction = false; } // This will take ownership of mCallback and make sure its destruction will // happen on the owner thread. Unused << mCallingThread->Dispatch( NewRunnableMethod(this, &AsyncExecuteStatements::notifyCompleteOnCallingThread), NS_DISPATCH_NORMAL); return NS_OK; } nsresult AsyncExecuteStatements::notifyCompleteOnCallingThread() { #ifdef DEBUG bool onCallingThread = false; (void)mCallingThread->IsOnCurrentThread(&onCallingThread); MOZ_ASSERT(onCallingThread); #endif // Take ownership of mCallback and responsibility for freeing it when we // release it. Any notifyResultsOnCallingThread and notifyErrorOnCallingThread // calls on the stack spinning the event loop have guaranteed their safety by // creating their own strong reference before invoking the callback. nsCOMPtr<mozIStorageStatementCallback> callback = mCallback.forget(); if (callback) { Unused << callback->HandleCompletion(mState); } return NS_OK; } nsresult AsyncExecuteStatements::notifyError(int32_t aErrorCode, const char *aMessage) { mMutex.AssertNotCurrentThreadOwns(); mDBMutex.assertNotCurrentThreadOwns(); if (!mCallback) return NS_OK; nsCOMPtr<mozIStorageError> errorObj(new Error(aErrorCode, aMessage)); NS_ENSURE_TRUE(errorObj, NS_ERROR_OUT_OF_MEMORY); return notifyError(errorObj); } nsresult AsyncExecuteStatements::notifyError(mozIStorageError *aError) { mMutex.AssertNotCurrentThreadOwns(); mDBMutex.assertNotCurrentThreadOwns(); if (!mCallback) return NS_OK; Unused << mCallingThread->Dispatch( NewRunnableMethod<nsCOMPtr<mozIStorageError>>(this, &AsyncExecuteStatements::notifyErrorOnCallingThread, aError), NS_DISPATCH_NORMAL); return NS_OK; } nsresult AsyncExecuteStatements::notifyErrorOnCallingThread(mozIStorageError *aError) { #ifdef DEBUG bool onCallingThread = false; (void)mCallingThread->IsOnCurrentThread(&onCallingThread); MOZ_ASSERT(onCallingThread); #endif // Acquire our own strong reference so that if the callback spins a nested // event loop and notifyCompleteOnCallingThread is executed, forgetting // mCallback, we still have a valid/strong reference that won't be freed until // we exit. nsCOMPtr<mozIStorageStatementCallback> callback = mCallback; if (shouldNotify() && callback) { Unused << callback->HandleError(aError); } return NS_OK; } nsresult AsyncExecuteStatements::notifyResults() { mMutex.AssertNotCurrentThreadOwns(); MOZ_ASSERT(mCallback, "notifyResults called without a callback!"); // This takes ownership of mResultSet, a new one will be generated in // buildAndNotifyResults() when further results will arrive. Unused << mCallingThread->Dispatch( NewRunnableMethod<RefPtr<ResultSet>>(this, &AsyncExecuteStatements::notifyResultsOnCallingThread, mResultSet.forget()), NS_DISPATCH_NORMAL); return NS_OK; } nsresult AsyncExecuteStatements::notifyResultsOnCallingThread(ResultSet *aResultSet) { #ifdef DEBUG bool onCallingThread = false; (void)mCallingThread->IsOnCurrentThread(&onCallingThread); MOZ_ASSERT(onCallingThread); #endif // Acquire our own strong reference so that if the callback spins a nested // event loop and notifyCompleteOnCallingThread is executed, forgetting // mCallback, we still have a valid/strong reference that won't be freed until // we exit. nsCOMPtr<mozIStorageStatementCallback> callback = mCallback; if (shouldNotify() && callback) { Unused << callback->HandleResult(aResultSet); } return NS_OK; } NS_IMPL_ISUPPORTS( AsyncExecuteStatements, nsIRunnable, mozIStoragePendingStatement ) bool AsyncExecuteStatements::statementsNeedTransaction() { // If there is more than one write statement, run in a transaction. // Additionally, if we have only one statement but it needs a transaction, due // to multiple BindingParams, we will wrap it in one. for (uint32_t i = 0, transactionsCount = 0; i < mStatements.Length(); ++i) { transactionsCount += mStatements[i].needsTransaction(); if (transactionsCount > 1) { return true; } } return false; } //////////////////////////////////////////////////////////////////////////////// //// mozIStoragePendingStatement NS_IMETHODIMP AsyncExecuteStatements::Cancel() { #ifdef DEBUG bool onCallingThread = false; (void)mCallingThread->IsOnCurrentThread(&onCallingThread); NS_ASSERTION(onCallingThread, "Not canceling from the calling thread!"); #endif // If we have already canceled, we have an error, but always indicate that // we are trying to cancel. NS_ENSURE_FALSE(mCancelRequested, NS_ERROR_UNEXPECTED); { MutexAutoLock lockedScope(mMutex); // We need to indicate that we want to try and cancel now. mCancelRequested = true; } return NS_OK; } //////////////////////////////////////////////////////////////////////////////// //// nsIRunnable NS_IMETHODIMP AsyncExecuteStatements::Run() { MOZ_ASSERT(!mConnection->isClosed()); // Do not run if we have been canceled. { MutexAutoLock lockedScope(mMutex); if (mCancelRequested) mState = CANCELED; } if (mState == CANCELED) return notifyComplete(); if (statementsNeedTransaction() && mConnection->getAutocommit()) { if (NS_SUCCEEDED(mConnection->beginTransactionInternal(mNativeConnection, mozIStorageConnection::TRANSACTION_IMMEDIATE))) { mHasTransaction = true; } #ifdef DEBUG else { NS_WARNING("Unable to create a transaction for async execution."); } #endif } // Execute each statement, giving the callback results if it returns any. for (uint32_t i = 0; i < mStatements.Length(); i++) { bool finished = (i == (mStatements.Length() - 1)); sqlite3_stmt *stmt; { // lock the sqlite mutex so sqlite3_errmsg cannot change SQLiteMutexAutoLock lockedScope(mDBMutex); int rc = mStatements[i].getSqliteStatement(&stmt); if (rc != SQLITE_OK) { // Set our error state. mState = ERROR; // Build the error object; can't call notifyError with the lock held nsCOMPtr<mozIStorageError> errorObj( new Error(rc, ::sqlite3_errmsg(mNativeConnection)) ); { // We cannot hold the DB mutex and call notifyError. SQLiteMutexAutoUnlock unlockedScope(mDBMutex); (void)notifyError(errorObj); } break; } } // If we have parameters to bind, bind them, execute, and process. if (mStatements[i].hasParametersToBeBound()) { if (!bindExecuteAndProcessStatement(mStatements[i], finished)) break; } // Otherwise, just execute and process the statement. else if (!executeAndProcessStatement(stmt, finished)) { break; } } // If we still have results that we haven't notified about, take care of // them now. if (mResultSet) (void)notifyResults(); // Notify about completion return notifyComplete(); } } // namespace storage } // namespace mozilla