mirror of https://github.com/facebook/rocksdb.git
69 lines
2.7 KiB
C++
69 lines
2.7 KiB
C++
// Copyright (c) 2013, Facebook, Inc. All rights reserved.
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// This source code is licensed under the BSD-style license found in the
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// LICENSE file in the root directory of this source tree. An additional grant
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// of patent rights can be found in the PATENTS file in the same directory.
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#pragma once
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#ifndef ROCKSDB_LITE
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#include <string>
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#include <vector>
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#include "utilities/stackable_db.h"
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#include "rocksdb/db.h"
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namespace rocksdb {
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// Database with TTL support.
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//
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// USE-CASES:
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// This API should be used to open the db when key-values inserted are
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// meant to be removed from the db in a non-strict 'ttl' amount of time
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// Therefore, this guarantees that key-values inserted will remain in the
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// db for >= ttl amount of time and the db will make efforts to remove the
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// key-values as soon as possible after ttl seconds of their insertion.
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//
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// BEHAVIOUR:
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// TTL is accepted in seconds
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// (int32_t)Timestamp(creation) is suffixed to values in Put internally
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// Expired TTL values deleted in compaction only:(Timestamp+ttl<time_now)
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// Get/Iterator may return expired entries(compaction not run on them yet)
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// Different TTL may be used during different Opens
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// Example: Open1 at t=0 with ttl=4 and insert k1,k2, close at t=2
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// Open2 at t=3 with ttl=5. Now k1,k2 should be deleted at t>=5
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// read_only=true opens in the usual read-only mode. Compactions will not be
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// triggered(neither manual nor automatic), so no expired entries removed
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//
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// CONSTRAINTS:
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// Not specifying/passing or non-positive TTL behaves like TTL = infinity
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//
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// !!!WARNING!!!:
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// Calling DB::Open directly to re-open a db created by this API will get
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// corrupt values(timestamp suffixed) and no ttl effect will be there
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// during the second Open, so use this API consistently to open the db
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// Be careful when passing ttl with a small positive value because the
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// whole database may be deleted in a small amount of time
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class DBWithTTL : public StackableDB {
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public:
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virtual Status CreateColumnFamilyWithTtl(
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const ColumnFamilyOptions& options, const std::string& column_family_name,
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ColumnFamilyHandle** handle, int ttl) = 0;
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static Status Open(const Options& options, const std::string& dbname,
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DBWithTTL** dbptr, int32_t ttl = 0,
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bool read_only = false);
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static Status Open(const DBOptions& db_options, const std::string& dbname,
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const std::vector<ColumnFamilyDescriptor>& column_families,
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std::vector<ColumnFamilyHandle*>* handles,
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DBWithTTL** dbptr, std::vector<int32_t> ttls,
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bool read_only = false);
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protected:
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explicit DBWithTTL(DB* db) : StackableDB(db) {}
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};
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} // namespace rocksdb
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#endif // ROCKSDB_LITE
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