98 lines
4.0 KiB
C++
98 lines
4.0 KiB
C++
/*
|
|
* LogSystemDiskQueueAdapter.h
|
|
*
|
|
* This source file is part of the FoundationDB open source project
|
|
*
|
|
* Copyright 2013-2018 Apple Inc. and the FoundationDB project authors
|
|
*
|
|
* 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.
|
|
*/
|
|
|
|
#ifndef FDBSERVER_LOGSYSTEMDISKQUEUEADAPTER_H
|
|
#define FDBSERVER_LOGSYSTEMDISKQUEUEADAPTER_H
|
|
#pragma once
|
|
|
|
#include "fdbclient/FDBTypes.h"
|
|
#include "IDiskQueue.h"
|
|
|
|
class LogSystemDiskQueueAdapter : public IDiskQueue {
|
|
public:
|
|
// This adapter is designed to let KeyValueStoreMemory use ILogSystem
|
|
// as a backing store, so that the transaction subsystem can in
|
|
// turn use KeyValueStoreMemory to track configuration information as of
|
|
// the database version and recover it from the logging subsystem as necessary.
|
|
|
|
// Because the transaction subsystem will need to control the actual pushing of
|
|
// committed information to the ILogSystem, commit() in this interface doesn't directly
|
|
// call ILogSystem::push(). Instead it makes a commit message available through
|
|
// getCommitMessage(), and doesn't return until its acknowledge promise is set.
|
|
// The caller is responsible for calling ILogSystem::push() and ILogSystem::pop() with the results.
|
|
|
|
// It does, however, peek the specified tag directly at recovery time.
|
|
|
|
LogSystemDiskQueueAdapter( Reference<ILogSystem> logSystem, Tag tag, bool recover=true ) : logSystem(logSystem), tag(tag), enableRecovery(recover), recoveryLoc(1), recoveryQueueLoc(1), poppedUpTo(0), nextCommit(1), recoveryQueueDataSize(0) {
|
|
if (enableRecovery)
|
|
cursor = logSystem->peek( UID(), 0, tag, true );
|
|
}
|
|
|
|
struct CommitMessage {
|
|
Standalone<VectorRef<VectorRef<uint8_t>>> messages; // push this into the logSystem with `tag`
|
|
Version popTo; // pop this from the logSystem with `tag`
|
|
Promise<Void> acknowledge; // then send Void to this, so commit() can return
|
|
};
|
|
|
|
// Set the version of the next push or commit (or a lower version)
|
|
// If lower, locations returned by the IDiskQueue interface will be conservative, so things that could be popped might not be
|
|
void setNextVersion( Version next ) { nextCommit = next; }
|
|
|
|
// Return the next commit message resulting from a call to commit().
|
|
Future<CommitMessage> getCommitMessage();
|
|
|
|
// IClosable interface
|
|
virtual Future<Void> getError();
|
|
virtual Future<Void> onClosed();
|
|
virtual void dispose();
|
|
virtual void close();
|
|
|
|
// IDiskQueue interface
|
|
virtual Future<Standalone<StringRef>> readNext( int bytes );
|
|
virtual IDiskQueue::location getNextReadLocation();
|
|
virtual IDiskQueue::location push( StringRef contents );
|
|
virtual void pop( IDiskQueue::location upTo );
|
|
virtual Future<Void> commit();
|
|
virtual StorageBytes getStorageBytes() { ASSERT(false); throw internal_error(); }
|
|
virtual int getCommitOverhead() { return 0; } //SOMEDAY: could this be more accurate?
|
|
|
|
private:
|
|
Reference<ILogSystem::IPeekCursor> cursor;
|
|
Tag tag;
|
|
|
|
// Recovery state (used while readNext() is being called repeatedly)
|
|
bool enableRecovery;
|
|
Reference<ILogSystem> logSystem;
|
|
Version recoveryLoc, recoveryQueueLoc;
|
|
std::vector<Standalone<StringRef>> recoveryQueue;
|
|
int recoveryQueueDataSize;
|
|
|
|
// State for next commit() call
|
|
Standalone<VectorRef<VectorRef<uint8_t>>> pushedData; // SOMEDAY: better representation?
|
|
Version poppedUpTo;
|
|
std::deque< Promise<CommitMessage> > commitMessages;
|
|
Version nextCommit;
|
|
|
|
friend class LogSystemDiskQueueAdapterImpl;
|
|
};
|
|
|
|
LogSystemDiskQueueAdapter* openDiskQueueAdapter( Reference<ILogSystem> logSystem, Tag tag );
|
|
|
|
#endif |