fd00f39f97
Summary: Before this PR, `get_iostats_context()` will silently return a nullptr if no thread_local support is detected. This can be the result of build_detect_platform's failure to compile the simple code snippet on certain platforms, as reported in https://github.com/facebook/mysql-5.6/issues/904. To be safe, we should fail the compilation if user does not opt out IOStatsContext and ROCKSDB_SUPPORT_THREAD_LOCAL is not defined. If RocksDB relies on c++11, can we just always use thread_local? It turns out there might be performance concerns (https://github.com/facebook/rocksdb/issues/5774), which is beyond the scope of this PR. We can revisit this later. Here, we stick to the original impl. Pull Request resolved: https://github.com/facebook/rocksdb/pull/8117 Reviewed By: ajkr Differential Revision: D27356847 Pulled By: riversand963 fbshipit-source-id: f7d5776842277598d8341b955febb601946801ae
65 lines
2.0 KiB
C++
65 lines
2.0 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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#pragma once
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#include <stdint.h>
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#include <string>
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#include "rocksdb/perf_level.h"
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// A thread local context for gathering io-stats efficiently and transparently.
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// Use SetPerfLevel(PerfLevel::kEnableTime) to enable time stats.
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namespace ROCKSDB_NAMESPACE {
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struct IOStatsContext {
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// reset all io-stats counter to zero
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void Reset();
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std::string ToString(bool exclude_zero_counters = false) const;
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// the thread pool id
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uint64_t thread_pool_id;
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// number of bytes that has been written.
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uint64_t bytes_written;
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// number of bytes that has been read.
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uint64_t bytes_read;
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// time spent in open() and fopen().
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uint64_t open_nanos;
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// time spent in fallocate().
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uint64_t allocate_nanos;
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// time spent in write() and pwrite().
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uint64_t write_nanos;
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// time spent in read() and pread()
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uint64_t read_nanos;
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// time spent in sync_file_range().
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uint64_t range_sync_nanos;
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// time spent in fsync
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uint64_t fsync_nanos;
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// time spent in preparing write (fallocate etc).
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uint64_t prepare_write_nanos;
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// time spent in Logger::Logv().
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uint64_t logger_nanos;
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// CPU time spent in write() and pwrite()
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uint64_t cpu_write_nanos;
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// CPU time spent in read() and pread()
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uint64_t cpu_read_nanos;
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};
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// If RocksDB is compiled with -DNIOSTATS_CONTEXT, then a pointer to a global,
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// non-thread-local IOStatsContext object will be returned. Attempts to update
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// this object will be ignored, and reading from it will also be no-op.
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// Otherwise,
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// a) if thread-local is supported on the platform, then a pointer to
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// a thread-local IOStatsContext object will be returned.
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// b) if thread-local is NOT supported, then compilation will fail.
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//
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// This function never returns nullptr.
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IOStatsContext* get_iostats_context();
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} // namespace ROCKSDB_NAMESPACE
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