void CmdInterpreter::beginTxn(ProxyBeginTxnCmd &cmd, bool readOnly, TxnId csn) { assert(readOnly || csn == NULL_TXN_ID); // block checkpoints during this method DbHandle *pDbHandle = getDbHandle(cmd.getDbHandle()); SharedDatabase pDb = pDbHandle->pDb; SXMutexSharedGuard actionMutexGuard( pDb->getCheckpointThread()->getActionMutex()); std::auto_ptr<TxnHandle> pTxnHandle(newTxnHandle()); JniUtil::incrementHandleCount(TXNHANDLE_TRACE_TYPE_STR, pTxnHandle.get()); pTxnHandle->pDb = pDb; pTxnHandle->readOnly = readOnly; // TODO: CacheAccessor factory pTxnHandle->pTxn = pDb->getTxnLog()->newLogicalTxn(pDb->getCache()); pTxnHandle->pResourceGovernor = pDbHandle->pResourceGovernor; // NOTE: use a null scratchAccessor; individual ExecStreamGraphs // will have their own SegmentAccessor scratchAccessor; pTxnHandle->pFtrsTableWriterFactory = SharedFtrsTableWriterFactory( new FtrsTableWriterFactory( pDb, pDb->getCache(), pDb->getTypeFactory(), scratchAccessor)); // If snapshots are enabled, set up 2 snapshot segments -- one of which // only reads committed data. This will be used for streams that need to // read a snapshot of the data before other portions of the stream graph // have modified the segment. if (pDb->areSnapshotsEnabled()) { if (csn == NULL_TXN_ID) { csn = pTxnHandle->pTxn->getTxnId(); } pTxnHandle->pSnapshotSegment = pDb->getSegmentFactory()->newSnapshotRandomAllocationSegment( pDb->getDataSegment(), pDb->getDataSegment(), csn, false); pTxnHandle->pReadCommittedSnapshotSegment = pDb->getSegmentFactory()->newSnapshotRandomAllocationSegment( pDb->getDataSegment(), pDb->getDataSegment(), csn, true); } else { assert(csn == NULL_TXN_ID); } setTxnHandle(cmd.getResultHandle(), pTxnHandle.release()); }
void CmdInterpreter::visit(ProxyCmdCommit &cmd) { TxnHandle *pTxnHandle = getTxnHandle(cmd.getTxnHandle()); SharedDatabase pDb = pTxnHandle->pDb; // block checkpoints during this method bool txnBlocksCheckpoint = !pTxnHandle->readOnly && pDb->shouldForceTxns(); SXMutexSharedGuard actionMutexGuard( pDb->getCheckpointThread()->getActionMutex()); if (pDb->areSnapshotsEnabled()) { // Commit the current txn, and start a new one so the versioned // pages that we're now going to commit will be marked with a txnId // corresponding to the time of the commit. At present, those pages // are marked with a txnId corresponding to the start of the txn. pTxnHandle->pTxn->commit(); pTxnHandle->pTxn = pDb->getTxnLog()->newLogicalTxn(pDb->getCache()); SnapshotRandomAllocationSegment *pSnapshotSegment = SegmentFactory::dynamicCast<SnapshotRandomAllocationSegment *>( pTxnHandle->pSnapshotSegment); TxnId commitTxnId = pTxnHandle->pTxn->getTxnId(); pSnapshotSegment->commitChanges(commitTxnId); // Flush pages associated with the snapshot segment. Note that we // don't need to flush the underlying versioned segment first since // the snapshot pages are all new and therefore, are never logged. // Pages in the underlying versioned segment will be flushed in the // requestCheckpoint call further below. Also note that the // checkpoint is not initiated through the dynamically cast segment // to ensure that the command is traced if tracing is turned on. if (txnBlocksCheckpoint) { pTxnHandle->pSnapshotSegment->checkpoint(CHECKPOINT_FLUSH_ALL); } } if (cmd.getSvptHandle()) { SavepointId svptId = getSavepointId(cmd.getSvptHandle()); pTxnHandle->pTxn->commitSavepoint(svptId); } else { pTxnHandle->pTxn->commit(); deleteAndNullify(pTxnHandle); if (txnBlocksCheckpoint) { // release the checkpoint lock acquired above actionMutexGuard.unlock(); // force a checkpoint now to flush all data modified by transaction // to disk; wait for it to complete before reporting the // transaction as committed pDb->requestCheckpoint(CHECKPOINT_FLUSH_ALL, false); } } }