rocksdb/utilities/blob_db/ttl_extractor.cc
Yi Wu 6083bc79f8 Blob DB TTL extractor
Summary:
Introducing blob_db::TTLExtractor to replace extract_ttl_fn. The TTL
extractor can be use to extract TTL from keys insert with Put or
WriteBatch. Change over existing extract_ttl_fn are:
* If value is changed, it will be return via std::string* (rather than Slice*). With Slice* the new value has to be part of the existing value. With std::string* the limitation is removed.
* It can optionally return TTL or expiration.

Other changes in this PR:
* replace `std::chrono::system_clock` with `Env::NowMicros` so that I can mock time in tests.
* add several TTL tests.
* other minor naming change.
Closes https://github.com/facebook/rocksdb/pull/2659

Differential Revision: D5512627

Pulled By: yiwu-arbug

fbshipit-source-id: 0dfcb00d74d060b8534c6130c808e4d5d0a54440
2017-07-27 23:26:04 -07:00

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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).
#include "ttl_extractor.h"
#include "util/coding.h"
namespace rocksdb {
namespace blob_db {
bool TTLExtractor::ExtractTTL(const Slice& /*key*/, const Slice& /*value*/,
uint64_t* /*ttl*/, std::string* /*new_value*/,
bool* /*value_changed*/) {
return false;
}
bool TTLExtractor::ExtractExpiration(const Slice& key, const Slice& value,
uint64_t now, uint64_t* expiration,
std::string* new_value,
bool* value_changed) {
uint64_t ttl;
bool has_ttl = ExtractTTL(key, value, &ttl, new_value, value_changed);
if (has_ttl) {
*expiration = now + ttl;
}
return has_ttl;
}
} // namespace blob_db
} // namespace rocksdb