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Diffstat (limited to 'src/rocksdb/file/random_access_file_reader.h')
-rw-r--r-- | src/rocksdb/file/random_access_file_reader.h | 120 |
1 files changed, 120 insertions, 0 deletions
diff --git a/src/rocksdb/file/random_access_file_reader.h b/src/rocksdb/file/random_access_file_reader.h new file mode 100644 index 000000000..35027bf45 --- /dev/null +++ b/src/rocksdb/file/random_access_file_reader.h @@ -0,0 +1,120 @@ +// Copyright (c) 2011-present, Facebook, Inc. All rights reserved. +// This source code is licensed under both the GPLv2 (found in the +// COPYING file in the root directory) and Apache 2.0 License +// (found in the LICENSE.Apache file in the root directory). +// +// Copyright (c) 2011 The LevelDB Authors. All rights reserved. +// Use of this source code is governed by a BSD-style license that can be +// found in the LICENSE file. See the AUTHORS file for names of contributors. + +#pragma once +#include <atomic> +#include <sstream> +#include <string> +#include "port/port.h" +#include "rocksdb/env.h" +#include "rocksdb/file_system.h" +#include "rocksdb/listener.h" +#include "rocksdb/rate_limiter.h" +#include "util/aligned_buffer.h" + +namespace ROCKSDB_NAMESPACE { +class Statistics; +class HistogramImpl; + +// RandomAccessFileReader is a wrapper on top of Env::RnadomAccessFile. It is +// responsible for: +// - Handling Buffered and Direct reads appropriately. +// - Rate limiting compaction reads. +// - Notifying any interested listeners on the completion of a read. +// - Updating IO stats. +class RandomAccessFileReader { + private: +#ifndef ROCKSDB_LITE + void NotifyOnFileReadFinish(uint64_t offset, size_t length, + const FileOperationInfo::TimePoint& start_ts, + const FileOperationInfo::TimePoint& finish_ts, + const Status& status) const { + FileOperationInfo info(file_name_, start_ts, finish_ts); + info.offset = offset; + info.length = length; + info.status = status; + + for (auto& listener : listeners_) { + listener->OnFileReadFinish(info); + } + } +#endif // ROCKSDB_LITE + + bool ShouldNotifyListeners() const { return !listeners_.empty(); } + + std::unique_ptr<FSRandomAccessFile> file_; + std::string file_name_; + Env* env_; + Statistics* stats_; + uint32_t hist_type_; + HistogramImpl* file_read_hist_; + RateLimiter* rate_limiter_; + std::vector<std::shared_ptr<EventListener>> listeners_; + + public: + explicit RandomAccessFileReader( + std::unique_ptr<FSRandomAccessFile>&& raf, std::string _file_name, + Env* env = nullptr, Statistics* stats = nullptr, uint32_t hist_type = 0, + HistogramImpl* file_read_hist = nullptr, + RateLimiter* rate_limiter = nullptr, + const std::vector<std::shared_ptr<EventListener>>& listeners = {}) + : file_(std::move(raf)), + file_name_(std::move(_file_name)), + env_(env), + stats_(stats), + hist_type_(hist_type), + file_read_hist_(file_read_hist), + rate_limiter_(rate_limiter), + listeners_() { +#ifndef ROCKSDB_LITE + std::for_each(listeners.begin(), listeners.end(), + [this](const std::shared_ptr<EventListener>& e) { + if (e->ShouldBeNotifiedOnFileIO()) { + listeners_.emplace_back(e); + } + }); +#else // !ROCKSDB_LITE + (void)listeners; +#endif + } + + RandomAccessFileReader(RandomAccessFileReader&& o) ROCKSDB_NOEXCEPT { + *this = std::move(o); + } + + RandomAccessFileReader& operator=(RandomAccessFileReader&& o) + ROCKSDB_NOEXCEPT { + file_ = std::move(o.file_); + env_ = std::move(o.env_); + stats_ = std::move(o.stats_); + hist_type_ = std::move(o.hist_type_); + file_read_hist_ = std::move(o.file_read_hist_); + rate_limiter_ = std::move(o.rate_limiter_); + return *this; + } + + RandomAccessFileReader(const RandomAccessFileReader&) = delete; + RandomAccessFileReader& operator=(const RandomAccessFileReader&) = delete; + + Status Read(uint64_t offset, size_t n, Slice* result, char* scratch, + bool for_compaction = false) const; + + Status MultiRead(FSReadRequest* reqs, size_t num_reqs) const; + + Status Prefetch(uint64_t offset, size_t n) const { + return file_->Prefetch(offset, n, IOOptions(), nullptr); + } + + FSRandomAccessFile* file() { return file_.get(); } + + std::string file_name() const { return file_name_; } + + bool use_direct_io() const { return file_->use_direct_io(); } +}; +} // namespace ROCKSDB_NAMESPACE |