rocksdb/utilities/blob_db/blob_db.h
Yi Wu 1209b6db5c Blob DB: remove existing garbage collection implementation
Summary:
Red diff to remove existing implementation of garbage collection. The current approach is reference counting kind of approach and require a lot of effort to get the size counter right on compaction and deletion. I'm going to go with a simple mark-sweep kind of approach and will send another PR for that.

CompactionEventListener was added solely for blob db and it adds complexity and overhead to compaction iterator. Removing it as well.
Closes https://github.com/facebook/rocksdb/pull/3551

Differential Revision: D7130190

Pulled By: yiwu-arbug

fbshipit-source-id: c3a375ad2639a3f6ed179df6eda602372cc5b8df
2018-03-02 12:57:23 -08:00

256 lines
9.6 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
#ifndef ROCKSDB_LITE
#include <functional>
#include <string>
#include <vector>
#include "rocksdb/db.h"
#include "rocksdb/status.h"
#include "rocksdb/utilities/stackable_db.h"
namespace rocksdb {
namespace blob_db {
class TTLExtractor;
// A wrapped database which puts values of KV pairs in a separate log
// and store location to the log in the underlying DB.
// It lacks lots of importatant functionalities, e.g. DB restarts,
// garbage collection, iterators, etc.
//
// The factory needs to be moved to include/rocksdb/utilities to allow
// users to use blob DB.
struct BlobDBOptions {
// name of the directory under main db, where blobs will be stored.
// default is "blob_dir"
std::string blob_dir = "blob_dir";
// whether the blob_dir path is relative or absolute.
bool path_relative = true;
// is the eviction strategy fifo based
bool is_fifo = false;
// maximum size of the blob dir. Once this gets used, up
// evict the blob file which is oldest (is_fifo )
// 0 means no limits
uint64_t blob_dir_size = 0;
// a new bucket is opened, for ttl_range. So if ttl_range is 600seconds
// (10 minutes), and the first bucket starts at 1471542000
// then the blob buckets will be
// first bucket is 1471542000 - 1471542600
// second bucket is 1471542600 - 1471543200
// and so on
uint64_t ttl_range_secs = 3600;
// The smallest value to store in blob log. Value larger than this threshold
// will be inlined in base DB together with the key.
uint64_t min_blob_size = 0;
// Allows OS to incrementally sync blob files to disk for every
// bytes_per_sync bytes written. Users shouldn't rely on it for
// persistency guarantee.
uint64_t bytes_per_sync = 512 * 1024;
// the target size of each blob file. File will become immutable
// after it exceeds that size
uint64_t blob_file_size = 256 * 1024 * 1024;
// Instead of setting TTL explicitly by calling PutWithTTL or PutUntil,
// applications can set a TTLExtractor which can extract TTL from key-value
// pairs.
std::shared_ptr<TTLExtractor> ttl_extractor = nullptr;
// what compression to use for Blob's
CompressionType compression = kNoCompression;
// If enabled, blob DB periodically cleanup stale data by rewriting remaining
// live data in blob files to new files. If garbage collection is not enabled,
// blob files will be cleanup based on TTL.
bool enable_garbage_collection = false;
// Time interval to trigger garbage collection, in seconds.
uint64_t garbage_collection_interval_secs = 60;
// If garbage collection is enabled, blob files with deleted size no less
// than this ratio will become candidates to be cleanup.
double garbage_collection_deletion_size_threshold = 0.75;
// Disable all background job. Used for test only.
bool disable_background_tasks = false;
void Dump(Logger* log) const;
};
class BlobDB : public StackableDB {
public:
using rocksdb::StackableDB::Put;
virtual Status Put(const WriteOptions& options, const Slice& key,
const Slice& value) override = 0;
virtual Status Put(const WriteOptions& options,
ColumnFamilyHandle* column_family, const Slice& key,
const Slice& value) override {
if (column_family != DefaultColumnFamily()) {
return Status::NotSupported(
"Blob DB doesn't support non-default column family.");
}
return Put(options, key, value);
}
using rocksdb::StackableDB::Delete;
virtual Status Delete(const WriteOptions& options,
ColumnFamilyHandle* column_family,
const Slice& key) override {
if (column_family != DefaultColumnFamily()) {
return Status::NotSupported(
"Blob DB doesn't support non-default column family.");
}
assert(db_ != nullptr);
return db_->Delete(options, column_family, key);
}
virtual Status PutWithTTL(const WriteOptions& options, const Slice& key,
const Slice& value, uint64_t ttl) = 0;
virtual Status PutWithTTL(const WriteOptions& options,
ColumnFamilyHandle* column_family, const Slice& key,
const Slice& value, uint64_t ttl) {
if (column_family != DefaultColumnFamily()) {
return Status::NotSupported(
"Blob DB doesn't support non-default column family.");
}
return PutWithTTL(options, key, value, ttl);
}
// Put with expiration. Key with expiration time equal to
// std::numeric_limits<uint64_t>::max() means the key don't expire.
virtual Status PutUntil(const WriteOptions& options, const Slice& key,
const Slice& value, uint64_t expiration) = 0;
virtual Status PutUntil(const WriteOptions& options,
ColumnFamilyHandle* column_family, const Slice& key,
const Slice& value, uint64_t expiration) {
if (column_family != DefaultColumnFamily()) {
return Status::NotSupported(
"Blob DB doesn't support non-default column family.");
}
return PutUntil(options, key, value, expiration);
}
using rocksdb::StackableDB::Get;
virtual Status Get(const ReadOptions& options,
ColumnFamilyHandle* column_family, const Slice& key,
PinnableSlice* value) override = 0;
using rocksdb::StackableDB::MultiGet;
virtual std::vector<Status> MultiGet(
const ReadOptions& options,
const std::vector<Slice>& keys,
std::vector<std::string>* values) override = 0;
virtual std::vector<Status> MultiGet(
const ReadOptions& options,
const std::vector<ColumnFamilyHandle*>& column_families,
const std::vector<Slice>& keys,
std::vector<std::string>* values) override {
for (auto column_family : column_families) {
if (column_family != DefaultColumnFamily()) {
return std::vector<Status>(
column_families.size(),
Status::NotSupported(
"Blob DB doesn't support non-default column family."));
}
}
return MultiGet(options, keys, values);
}
using rocksdb::StackableDB::SingleDelete;
virtual Status SingleDelete(const WriteOptions& /*wopts*/,
ColumnFamilyHandle* /*column_family*/,
const Slice& /*key*/) override {
return Status::NotSupported("Not supported operation in blob db.");
}
using rocksdb::StackableDB::Merge;
virtual Status Merge(const WriteOptions& /*options*/,
ColumnFamilyHandle* /*column_family*/,
const Slice& /*key*/, const Slice& /*value*/) override {
return Status::NotSupported("Not supported operation in blob db.");
}
virtual Status Write(const WriteOptions& opts,
WriteBatch* updates) override = 0;
using rocksdb::StackableDB::NewIterator;
virtual Iterator* NewIterator(const ReadOptions& options) override = 0;
virtual Iterator* NewIterator(const ReadOptions& options,
ColumnFamilyHandle* column_family) override {
if (column_family != DefaultColumnFamily()) {
// Blob DB doesn't support non-default column family.
return nullptr;
}
return NewIterator(options);
}
// Opening blob db.
static Status Open(const Options& options, const BlobDBOptions& bdb_options,
const std::string& dbname, BlobDB** blob_db);
static Status Open(const DBOptions& db_options,
const BlobDBOptions& bdb_options,
const std::string& dbname,
const std::vector<ColumnFamilyDescriptor>& column_families,
std::vector<ColumnFamilyHandle*>* handles,
BlobDB** blob_db);
virtual BlobDBOptions GetBlobDBOptions() const = 0;
virtual Status SyncBlobFiles() = 0;
virtual ~BlobDB() {}
protected:
explicit BlobDB();
};
// Destroy the content of the database.
Status DestroyBlobDB(const std::string& dbname, const Options& options,
const BlobDBOptions& bdb_options);
// TTLExtractor allow applications to extract TTL from key-value pairs.
// This useful for applications using Put or WriteBatch to write keys and
// don't intend to migrate to PutWithTTL or PutUntil.
//
// Applications can implement either ExtractTTL or ExtractExpiration. If both
// are implemented, ExtractExpiration will take precedence.
class TTLExtractor {
public:
// Extract TTL from key-value pair.
// Return true if the key has TTL, false otherwise. If key has TTL,
// TTL is pass back through ttl. The method can optionally modify the value,
// pass the result back through new_value, and also set value_changed to true.
virtual bool ExtractTTL(const Slice& key, const Slice& value, uint64_t* ttl,
std::string* new_value, bool* value_changed);
// Extract expiration time from key-value pair.
// Return true if the key has expiration time, false otherwise. If key has
// expiration time, it is pass back through expiration. The method can
// optionally modify the value, pass the result back through new_value,
// and also set value_changed to true.
virtual bool ExtractExpiration(const Slice& key, const Slice& value,
uint64_t now, uint64_t* expiration,
std::string* new_value, bool* value_changed);
virtual ~TTLExtractor() = default;
};
} // namespace blob_db
} // namespace rocksdb
#endif // ROCKSDB_LITE