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// 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
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