bd45633b71
Summary: @igor pointed out that there is a potential data race because of the way we use the newly introduced LogBuffer. After "bg_compaction_scheduled_--" or "bg_flush_scheduled_--", they can both become 0. As soon as the lock is released after that, DBImpl's deconstructor can go ahead and deconstruct all the states inside DB, including the info_log object hold in a shared pointer of the options object it keeps. At that point it is not safe anymore to continue using the info logger to write the delayed logs. With the patch, lock is released temporarily for log buffer to be flushed before "bg_compaction_scheduled_--" or "bg_flush_scheduled_--". In order to make sure we don't miss any pending flush or compaction, a new flag bg_schedule_needed_ is added, which is set to be true if there is a pending flush or compaction but not scheduled because of the max thread limit. If the flag is set to be true, the scheduling function will be called before compaction or flush thread finishes. Thanks @igor for this finding! Test Plan: make all check Reviewers: haobo, igor Reviewed By: haobo CC: dhruba, ljin, yhchiang, igor, leveldb Differential Revision: https://reviews.facebook.net/D16767
49 lines
1.4 KiB
C++
49 lines
1.4 KiB
C++
// Copyright (c) 2014, Facebook, Inc. All rights reserved.
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// This source code is licensed under the BSD-style license found in the
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// LICENSE file in the root directory of this source tree. An additional grant
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// of patent rights can be found in the PATENTS file in the same directory.
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#pragma once
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#include "rocksdb/env.h"
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#include "util/arena.h"
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#include "util/autovector.h"
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namespace rocksdb {
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class Logger;
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// A class to buffer info log entries and flush them in the end.
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class LogBuffer {
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public:
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// log_level: the log level for all the logs
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// info_log: logger to write the logs to
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LogBuffer(const InfoLogLevel log_level, Logger* info_log);
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// Add a log entry to the buffer.
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void AddLogToBuffer(const char* format, va_list ap);
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size_t IsEmpty() const { return logs_.empty(); }
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// Flush all buffered log to the info log.
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void FlushBufferToLog();
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private:
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// One log entry with its timestamp
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struct BufferedLog {
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struct timeval now_tv; // Timestamp of the log
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char message[1]; // Beginning of log message
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};
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const InfoLogLevel log_level_;
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Logger* info_log_;
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Arena arena_;
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autovector<BufferedLog*> logs_;
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};
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// Add log to the LogBuffer for a delayed info logging. It can be used when
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// we want to add some logs inside a mutex.
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extern void LogToBuffer(LogBuffer* log_buffer, const char* format, ...);
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} // namespace rocksdb
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