mirror of https://github.com/facebook/rocksdb.git
63 lines
2.4 KiB
C++
63 lines
2.4 KiB
C++
// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
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// This source code is licensed under both the GPLv2 (found in the
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// COPYING file in the root directory) and Apache 2.0 License
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// (found in the LICENSE.Apache file in the root directory).
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//
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#pragma once
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#include <cassert>
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#include <cstdint>
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#include <cstdlib>
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#include <mutex>
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#include <unordered_map>
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#include <vector>
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#include "rocksdb/rocksdb_namespace.h"
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namespace ROCKSDB_NAMESPACE {
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// This class is used to track the log files with outstanding prepare entries.
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class LogsWithPrepTracker {
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public:
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// Called when a transaction prepared in `log` has been committed or aborted.
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void MarkLogAsHavingPrepSectionFlushed(uint64_t log);
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// Called when a transaction is prepared in `log`.
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void MarkLogAsContainingPrepSection(uint64_t log);
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// Return the earliest log file with outstanding prepare entries.
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uint64_t FindMinLogContainingOutstandingPrep();
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size_t TEST_PreparedSectionCompletedSize() {
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return prepared_section_completed_.size();
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}
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size_t TEST_LogsWithPrepSize() { return logs_with_prep_.size(); }
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private:
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// REQUIRES: logs_with_prep_mutex_ held
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//
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// sorted list of log numbers still containing prepared data.
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// this is used by FindObsoleteFiles to determine which
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// flushed logs we must keep around because they still
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// contain prepared data which has not been committed or rolled back
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struct LogCnt {
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uint64_t log; // the log number
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uint64_t cnt; // number of prepared sections in the log
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};
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std::vector<LogCnt> logs_with_prep_;
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std::mutex logs_with_prep_mutex_;
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// REQUIRES: prepared_section_completed_mutex_ held
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//
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// to be used in conjunction with logs_with_prep_.
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// once a transaction with data in log L is committed or rolled back
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// rather than updating logs_with_prep_ directly we keep track of that
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// in prepared_section_completed_ which maps LOG -> instance_count. This helps
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// avoiding contention between a commit thread and the prepare threads.
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//
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// when trying to determine the minimum log still active we first
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// consult logs_with_prep_. while that root value maps to
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// an equal value in prepared_section_completed_ we erase the log from
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// both logs_with_prep_ and prepared_section_completed_.
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std::unordered_map<uint64_t, uint64_t> prepared_section_completed_;
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std::mutex prepared_section_completed_mutex_;
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};
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} // namespace ROCKSDB_NAMESPACE
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