3102628873
Summary: added an argument to openttldb for read only and open the db in normal readonly mode if the arguments is set to true Test Plan: make ttl_test; ./ttl_test Reviewers: dhruba, haobo, vamsi, sheki Reviewed By: dhruba CC: leveldb Differential Revision: https://reviews.facebook.net/D10749
56 lines
2.4 KiB
C++
56 lines
2.4 KiB
C++
// 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.
|
|
|
|
#ifndef LEVELDB_INCLUDE_UTILITIES_UTILITY_DB_H_
|
|
#define LEVELDB_INCLUDE_UTILITIES_UTILITY_DB_H_
|
|
|
|
#include "leveldb/db.h"
|
|
|
|
namespace leveldb {
|
|
|
|
// This class contains APIs to open leveldb with specific support eg. TTL
|
|
class UtilityDB {
|
|
|
|
public:
|
|
// Open the database with TTL support.
|
|
//
|
|
// USE-CASES:
|
|
// This API should be used to open the db when key-values inserted are
|
|
// meant to be removed from the db in a non-strict 'ttl' amount of time
|
|
// Therefore, this guarantees that key-values inserted will remain in the
|
|
// db for >= ttl amount of time and the db will make efforts to remove the
|
|
// key-values as soon as possible after ttl seconds of their insertion.
|
|
//
|
|
// BEHAVIOUR:
|
|
// TTL is accepted in seconds
|
|
// (int32_t)Timestamp(creation) is suffixed to values in Put internally
|
|
// Expired TTL values deleted in compaction only:(Timestamp+ttl<time_now)
|
|
// Get/Iterator may return expired entries(compaction not run on them yet)
|
|
// Different TTL may be used during different Opens
|
|
// Example: Open1 at t=0 with ttl=4 and insert k1,k2, close at t=2
|
|
// Open2 at t=3 with ttl=5. Now k1,k2 should be deleted at t>=5
|
|
// read_only=true opens in the usual read-only mode. Compactions will not be
|
|
// triggered(neither manual nor automatic), so no expired entries removed
|
|
//
|
|
// CONSTRAINTS:
|
|
// The caller must not specify any compaction-filter in options
|
|
// Not specifying/passing or non-positive TTL behaves like TTL = infinity
|
|
//
|
|
// !!!WARNING!!!:
|
|
// Calling DB::Open directly to re-open a db created by this API will get
|
|
// corrupt values(timestamp suffixed) and no ttl effect will be there
|
|
// during the second Open, so use this API consistently to open the db
|
|
// Be careful when passing ttl with a small positive value because the
|
|
// whole database may be deleted in a small amount of time
|
|
static Status OpenTtlDB(const Options& options,
|
|
const std::string& name,
|
|
DB** dbptr,
|
|
int32_t ttl = 0,
|
|
bool read_only = false);
|
|
};
|
|
|
|
} // namespace leveldb
|
|
|
|
#endif // LEVELDB_INCLUDE_UTILITIES_UTILITY_DB_H_
|