61 lines
2.8 KiB
C++
61 lines
2.8 KiB
C++
/*
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* IDiskQueue.h
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*
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* This source file is part of the FoundationDB open source project
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*
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* Copyright 2013-2018 Apple Inc. and the FoundationDB project authors
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef FDBSERVER_IDISKQUEUE_H
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#define FDBSERVER_IDISKQUEUE_H
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#pragma once
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#include "fdbclient/FDBTypes.h"
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#include "IKeyValueStore.h"
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class IDiskQueue : public IClosable {
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public:
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struct location {
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int64_t hi, lo;
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location() : hi(0), lo(0) {}
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location(int64_t lo) : hi(0), lo(lo) {}
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location(int64_t hi, int64_t lo) : hi(hi), lo(lo) {}
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operator std::string() { return format("%lld.%lld", hi, lo); } // FIXME: Return a 'HumanReadableDescription' instead of std::string, make TraceEvent::detail accept that (for safety)
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bool operator < (location const& r) const {
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if (hi<r.hi) return true;
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if (hi>r.hi) return false;
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return lo < r.lo;
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}
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};
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// Before calling push or commit, the caller *must* perform recovery by calling readNext() until it returns less than the requested number of bytes.
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// Thereafter it may not be called again.
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virtual Future<Standalone<StringRef>> readNext( int bytes ) = 0; // Return the next bytes in the queue (beginning, the first time called, with the first unpopped byte)
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virtual location getNextReadLocation() = 0; // Returns a location >= the location of all bytes previously returned by readNext(), and <= the location of all bytes subsequently returned
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virtual location push( StringRef contents ) = 0; // Appends the given bytes to the byte stream. Returns a location token representing the *end* of the contents.
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virtual void pop( location upTo ) = 0; // Removes all bytes before the given location token from the byte stream.
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virtual Future<Void> commit() = 0; // returns when all prior pushes and pops are durable. If commit does not return (due to close or a crash), any prefix of the pushed bytes and any prefix of the popped bytes may be durable.
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virtual int getCommitOverhead() = 0; // returns the amount of unused space that would be written by a commit that immediately followed this call
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virtual StorageBytes getStorageBytes() = 0;
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};
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IDiskQueue* openDiskQueue( std::string basename, UID dbgid, int64_t fileSizeWarningLimit = -1 ); // opens basename+"0.fdq" and basename+"1.fdq"
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#endif
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