rocksdb/utilities/blob_db/blob_file.h

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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).
#pragma once
#ifndef ROCKSDB_LITE
#include <atomic>
#include <limits>
#include <memory>
#include <unordered_set>
#include "file/random_access_file_reader.h"
#include "port/port.h"
#include "rocksdb/env.h"
#include "rocksdb/options.h"
#include "utilities/blob_db/blob_log_format.h"
#include "utilities/blob_db/blob_log_reader.h"
#include "utilities/blob_db/blob_log_writer.h"
namespace rocksdb {
namespace blob_db {
class BlobDBImpl;
class BlobFile {
friend class BlobDBImpl;
friend struct BlobFileComparator;
friend struct BlobFileComparatorTTL;
private:
// access to parent
const BlobDBImpl* parent_{nullptr};
// path to blob directory
std::string path_to_dir_;
// the id of the file.
// the above 2 are created during file creation and never changed
// after that
uint64_t file_number_{0};
// The file numbers of the SST files whose oldest blob file reference
// points to this blob file.
std::unordered_set<uint64_t> linked_sst_files_;
// Info log.
Logger* info_log_{nullptr};
// Column family id.
uint32_t column_family_id_{std::numeric_limits<uint32_t>::max()};
// Compression type of blobs in the file
CompressionType compression_{kNoCompression};
// If true, the keys in this file all has TTL. Otherwise all keys don't
// have TTL.
bool has_ttl_{false};
// TTL range of blobs in the file.
ExpirationRange expiration_range_;
// number of blobs in the file
std::atomic<uint64_t> blob_count_{0};
// size of the file
std::atomic<uint64_t> file_size_{0};
BlobLogHeader header_;
// closed_ = true implies the file is no more mutable
// no more blobs will be appended and the footer has been written out
std::atomic<bool> closed_{false};
// The latest sequence number when the file was closed/made immutable.
SequenceNumber immutable_sequence_{0};
// has a pass of garbage collection successfully finished on this file
// obsolete_ still needs to do iterator/snapshot checks
std::atomic<bool> obsolete_{false};
// The last sequence number by the time the file marked as obsolete.
// Data in this file is visible to a snapshot taken before the sequence.
SequenceNumber obsolete_sequence_{0};
// Sequential/Append writer for blobs
std::shared_ptr<Writer> log_writer_;
// random access file reader for GET calls
std::shared_ptr<RandomAccessFileReader> ra_file_reader_;
// This Read-Write mutex is per file specific and protects
// all the datastructures
mutable port::RWMutex mutex_;
// time when the random access reader was last created.
std::atomic<std::int64_t> last_access_{-1};
// last time file was fsync'd/fdatasyncd
std::atomic<uint64_t> last_fsync_{0};
bool header_valid_{false};
bool footer_valid_{false};
public:
BlobFile() = default;
BlobFile(const BlobDBImpl* parent, const std::string& bdir, uint64_t fnum,
Logger* info_log);
BlobFile(const BlobDBImpl* parent, const std::string& bdir, uint64_t fnum,
Logger* info_log, uint32_t column_family_id,
CompressionType compression, bool has_ttl,
const ExpirationRange& expiration_range);
~BlobFile();
uint32_t column_family_id() const;
// Returns log file's absolute pathname.
std::string PathName() const;
// Primary identifier for blob file.
// once the file is created, this never changes
uint64_t BlobFileNumber() const { return file_number_; }
// Get the set of SST files whose oldest blob file reference points to
// this file.
const std::unordered_set<uint64_t>& GetLinkedSstFiles() const {
return linked_sst_files_;
}
// Link an SST file whose oldest blob file reference points to this file.
void LinkSstFile(uint64_t sst_file_number) {
assert(linked_sst_files_.find(sst_file_number) == linked_sst_files_.end());
linked_sst_files_.insert(sst_file_number);
}
// Unlink an SST file whose oldest blob file reference points to this file.
void UnlinkSstFile(uint64_t sst_file_number) {
auto it = linked_sst_files_.find(sst_file_number);
assert(it != linked_sst_files_.end());
linked_sst_files_.erase(it);
}
// the following functions are atomic, and don't need
// read lock
uint64_t BlobCount() const {
return blob_count_.load(std::memory_order_acquire);
}
std::string DumpState() const;
// if the file is not taking any more appends.
bool Immutable() const { return closed_.load(); }
// Mark the file as immutable.
// REQUIRES: write lock held, or access from single thread (on DB open).
void MarkImmutable(SequenceNumber sequence) {
closed_ = true;
immutable_sequence_ = sequence;
}
SequenceNumber GetImmutableSequence() const {
assert(Immutable());
return immutable_sequence_;
}
// if the file has gone through GC and blobs have been relocated
bool Obsolete() const {
assert(Immutable() || !obsolete_.load());
return obsolete_.load();
}
// Mark file as obsolete by garbage collection. The file is not visible to
// snapshots with sequence greater or equal to the given sequence.
void MarkObsolete(SequenceNumber sequence);
SequenceNumber GetObsoleteSequence() const {
assert(Obsolete());
return obsolete_sequence_;
}
// we will assume this is atomic
bool NeedsFsync(bool hard, uint64_t bytes_per_sync) const;
Status Fsync();
uint64_t GetFileSize() const {
return file_size_.load(std::memory_order_acquire);
}
// All Get functions which are not atomic, will need ReadLock on the mutex
ExpirationRange GetExpirationRange() const { return expiration_range_; }
void ExtendExpirationRange(uint64_t expiration) {
expiration_range_.first = std::min(expiration_range_.first, expiration);
expiration_range_.second = std::max(expiration_range_.second, expiration);
}
bool HasTTL() const { return has_ttl_; }
void SetHasTTL(bool has_ttl) { has_ttl_ = has_ttl; }
CompressionType compression() const { return compression_; }
std::shared_ptr<Writer> GetWriter() const { return log_writer_; }
// Read blob file header and footer. Return corruption if file header is
// malform or incomplete. If footer is malform or incomplete, set
// footer_valid_ to false and return Status::OK.
Status ReadMetadata(Env* env, const EnvOptions& env_options);
Status GetReader(Env* env, const EnvOptions& env_options,
std::shared_ptr<RandomAccessFileReader>* reader,
bool* fresh_open);
private:
std::shared_ptr<Reader> OpenRandomAccessReader(
Env* env, const DBOptions& db_options,
const EnvOptions& env_options) const;
Status ReadFooter(BlobLogFooter* footer);
Status WriteFooterAndCloseLocked(SequenceNumber sequence);
void CloseRandomAccessLocked();
// this is used, when you are reading only the footer of a
// previously closed file
Status SetFromFooterLocked(const BlobLogFooter& footer);
void set_expiration_range(const ExpirationRange& expiration_range) {
expiration_range_ = expiration_range;
}
// The following functions are atomic, and don't need locks
void SetFileSize(uint64_t fs) { file_size_ = fs; }
void SetBlobCount(uint64_t bc) { blob_count_ = bc; }
};
} // namespace blob_db
} // namespace rocksdb
#endif // ROCKSDB_LITE