rocksdb/db/memtable_list.h
Yi Wu d1cab2b64e Add ValueType::kTypeBlobIndex
Summary:
Add kTypeBlobIndex value type, which will be used by blob db only, to insert a (key, blob_offset) KV pair. The purpose is to
1. Make it possible to open existing rocksdb instance as blob db. Existing value will be of kTypeIndex type, while value inserted by blob db will be of kTypeBlobIndex.
2. Make rocksdb able to detect if the db contains value written by blob db, if so return error.
3. Make it possible to have blob db optionally store value in SST file (with kTypeValue type) or as a blob value (with kTypeBlobIndex type).

The root db (DBImpl) basically pretended kTypeBlobIndex are normal value on write. On Get if is_blob is provided, return whether the value read is of kTypeBlobIndex type, or return Status::NotSupported() status if is_blob is not provided. On scan allow_blob flag is pass and if the flag is true, return wether the value is of kTypeBlobIndex type via iter->IsBlob().

Changes on blob db side will be in a separate patch.
Closes https://github.com/facebook/rocksdb/pull/2886

Differential Revision: D5838431

Pulled By: yiwu-arbug

fbshipit-source-id: 3c5306c62bc13bb11abc03422ec5cbcea1203cca
2017-10-03 09:11:23 -07:00

264 lines
9.8 KiB
C++

// 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
#include <string>
#include <list>
#include <vector>
#include <set>
#include <deque>
#include "db/dbformat.h"
#include "db/memtable.h"
#include "db/range_del_aggregator.h"
#include "monitoring/instrumented_mutex.h"
#include "rocksdb/db.h"
#include "rocksdb/iterator.h"
#include "rocksdb/options.h"
#include "rocksdb/types.h"
#include "util/autovector.h"
#include "util/filename.h"
#include "util/log_buffer.h"
namespace rocksdb {
class ColumnFamilyData;
class InternalKeyComparator;
class InstrumentedMutex;
class MergeIteratorBuilder;
// keeps a list of immutable memtables in a vector. the list is immutable
// if refcount is bigger than one. It is used as a state for Get() and
// Iterator code paths
//
// This class is not thread-safe. External synchronization is required
// (such as holding the db mutex or being on the write thread).
class MemTableListVersion {
public:
explicit MemTableListVersion(size_t* parent_memtable_list_memory_usage,
MemTableListVersion* old = nullptr);
explicit MemTableListVersion(size_t* parent_memtable_list_memory_usage,
int max_write_buffer_number_to_maintain);
void Ref();
void Unref(autovector<MemTable*>* to_delete = nullptr);
// Search all the memtables starting from the most recent one.
// Return the most recent value found, if any.
//
// If any operation was found for this key, its most recent sequence number
// will be stored in *seq on success (regardless of whether true/false is
// returned). Otherwise, *seq will be set to kMaxSequenceNumber.
bool Get(const LookupKey& key, std::string* value, Status* s,
MergeContext* merge_context, RangeDelAggregator* range_del_agg,
SequenceNumber* seq, const ReadOptions& read_opts,
ReadCallback* callback = nullptr, bool* is_blob_index = nullptr);
bool Get(const LookupKey& key, std::string* value, Status* s,
MergeContext* merge_context, RangeDelAggregator* range_del_agg,
const ReadOptions& read_opts, ReadCallback* callback = nullptr,
bool* is_blob_index = nullptr) {
SequenceNumber seq;
return Get(key, value, s, merge_context, range_del_agg, &seq, read_opts,
callback, is_blob_index);
}
// Similar to Get(), but searches the Memtable history of memtables that
// have already been flushed. Should only be used from in-memory only
// queries (such as Transaction validation) as the history may contain
// writes that are also present in the SST files.
bool GetFromHistory(const LookupKey& key, std::string* value, Status* s,
MergeContext* merge_context,
RangeDelAggregator* range_del_agg, SequenceNumber* seq,
const ReadOptions& read_opts);
bool GetFromHistory(const LookupKey& key, std::string* value, Status* s,
MergeContext* merge_context,
RangeDelAggregator* range_del_agg,
const ReadOptions& read_opts) {
SequenceNumber seq;
return GetFromHistory(key, value, s, merge_context, range_del_agg, &seq,
read_opts);
}
Status AddRangeTombstoneIterators(const ReadOptions& read_opts, Arena* arena,
RangeDelAggregator* range_del_agg);
Status AddRangeTombstoneIterators(
const ReadOptions& read_opts,
std::vector<InternalIterator*>* range_del_iters);
void AddIterators(const ReadOptions& options,
std::vector<InternalIterator*>* iterator_list,
Arena* arena);
void AddIterators(const ReadOptions& options,
MergeIteratorBuilder* merge_iter_builder);
uint64_t GetTotalNumEntries() const;
uint64_t GetTotalNumDeletes() const;
MemTable::MemTableStats ApproximateStats(const Slice& start_ikey,
const Slice& end_ikey);
// Returns the value of MemTable::GetEarliestSequenceNumber() on the most
// recent MemTable in this list or kMaxSequenceNumber if the list is empty.
// If include_history=true, will also search Memtables in MemTableList
// History.
SequenceNumber GetEarliestSequenceNumber(bool include_history = false) const;
private:
// REQUIRE: m is an immutable memtable
void Add(MemTable* m, autovector<MemTable*>* to_delete);
// REQUIRE: m is an immutable memtable
void Remove(MemTable* m, autovector<MemTable*>* to_delete);
void TrimHistory(autovector<MemTable*>* to_delete);
bool GetFromList(std::list<MemTable*>* list, const LookupKey& key,
std::string* value, Status* s, MergeContext* merge_context,
RangeDelAggregator* range_del_agg, SequenceNumber* seq,
const ReadOptions& read_opts,
ReadCallback* callback = nullptr,
bool* is_blob_index = nullptr);
void AddMemTable(MemTable* m);
void UnrefMemTable(autovector<MemTable*>* to_delete, MemTable* m);
friend class MemTableList;
// Immutable MemTables that have not yet been flushed.
std::list<MemTable*> memlist_;
// MemTables that have already been flushed
// (used during Transaction validation)
std::list<MemTable*> memlist_history_;
// Maximum number of MemTables to keep in memory (including both flushed
// and not-yet-flushed tables).
const int max_write_buffer_number_to_maintain_;
int refs_ = 0;
size_t* parent_memtable_list_memory_usage_;
};
// This class stores references to all the immutable memtables.
// The memtables are flushed to L0 as soon as possible and in
// any order. If there are more than one immutable memtable, their
// flushes can occur concurrently. However, they are 'committed'
// to the manifest in FIFO order to maintain correctness and
// recoverability from a crash.
//
//
// Other than imm_flush_needed, this class is not thread-safe and requires
// external synchronization (such as holding the db mutex or being on the
// write thread.)
class MemTableList {
public:
// A list of memtables.
explicit MemTableList(int min_write_buffer_number_to_merge,
int max_write_buffer_number_to_maintain)
: imm_flush_needed(false),
min_write_buffer_number_to_merge_(min_write_buffer_number_to_merge),
current_(new MemTableListVersion(&current_memory_usage_,
max_write_buffer_number_to_maintain)),
num_flush_not_started_(0),
commit_in_progress_(false),
flush_requested_(false) {
current_->Ref();
current_memory_usage_ = 0;
}
// Should not delete MemTableList without making sure MemTableList::current()
// is Unref()'d.
~MemTableList() {}
MemTableListVersion* current() { return current_; }
// so that background threads can detect non-nullptr pointer to
// determine whether there is anything more to start flushing.
std::atomic<bool> imm_flush_needed;
// Returns the total number of memtables in the list that haven't yet
// been flushed and logged.
int NumNotFlushed() const;
// Returns total number of memtables in the list that have been
// completely flushed and logged.
int NumFlushed() const;
// Returns true if there is at least one memtable on which flush has
// not yet started.
bool IsFlushPending() const;
// Returns the earliest memtables that needs to be flushed. The returned
// memtables are guaranteed to be in the ascending order of created time.
void PickMemtablesToFlush(autovector<MemTable*>* mems);
// Reset status of the given memtable list back to pending state so that
// they can get picked up again on the next round of flush.
void RollbackMemtableFlush(const autovector<MemTable*>& mems,
uint64_t file_number);
// Commit a successful flush in the manifest file
Status InstallMemtableFlushResults(
ColumnFamilyData* cfd, const MutableCFOptions& mutable_cf_options,
const autovector<MemTable*>& m, VersionSet* vset, InstrumentedMutex* mu,
uint64_t file_number, autovector<MemTable*>* to_delete,
Directory* db_directory, LogBuffer* log_buffer);
// New memtables are inserted at the front of the list.
// Takes ownership of the referenced held on *m by the caller of Add().
void Add(MemTable* m, autovector<MemTable*>* to_delete);
// Returns an estimate of the number of bytes of data in use.
size_t ApproximateMemoryUsage();
// Returns an estimate of the number of bytes of data used by
// the unflushed mem-tables.
size_t ApproximateUnflushedMemTablesMemoryUsage();
// Request a flush of all existing memtables to storage. This will
// cause future calls to IsFlushPending() to return true if this list is
// non-empty (regardless of the min_write_buffer_number_to_merge
// parameter). This flush request will persist until the next time
// PickMemtablesToFlush() is called.
void FlushRequested() { flush_requested_ = true; }
bool HasFlushRequested() { return flush_requested_; }
// Copying allowed
// MemTableList(const MemTableList&);
// void operator=(const MemTableList&);
size_t* current_memory_usage() { return &current_memory_usage_; }
uint64_t GetMinLogContainingPrepSection();
private:
// DB mutex held
void InstallNewVersion();
const int min_write_buffer_number_to_merge_;
MemTableListVersion* current_;
// the number of elements that still need flushing
int num_flush_not_started_;
// committing in progress
bool commit_in_progress_;
// Requested a flush of all memtables to storage
bool flush_requested_;
// The current memory usage.
size_t current_memory_usage_;
};
} // namespace rocksdb