foundationdb/fdbserver/workloads/MemoryKeyValueStore.cpp

144 lines
4.3 KiB
C++

/*
* MemoryKeyValueStore.cpp
*
* This source file is part of the FoundationDB open source project
*
* Copyright 2013-2018 Apple Inc. and the FoundationDB project authors
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "fdbserver/workloads/MemoryKeyValueStore.h"
// Get the value associated with a key
Optional<Value> MemoryKeyValueStore::get(KeyRef key) const {
std::map<Key, Value>::const_iterator value = store.find(key);
if (value != store.end())
return value->second;
else
return Optional<Value>();
}
// Returns the key designated by a key selector
Key MemoryKeyValueStore::getKey(KeySelectorRef selector) const {
// Begin by getting the start key referenced by the key selector
std::map<Key, Value>::const_iterator mapItr = store.lower_bound(selector.getKey());
// Update the iterator position if necessary based on the value of orEqual
int count = 0;
if (selector.offset <= 0) {
if (mapItr == store.end() || selector.getKey() != mapItr->first || !selector.orEqual) {
if (mapItr == store.begin())
return startKey();
mapItr--;
}
} else {
if (mapItr == store.end())
return endKey();
if (selector.getKey() == mapItr->first && selector.orEqual) {
mapItr++;
}
count++;
}
// Increment the map iterator until the desired offset is reached
for (; count < abs(selector.offset); count++) {
if (selector.offset < 0) {
if (mapItr == store.begin())
break;
mapItr--;
} else {
if (mapItr == store.end())
break;
mapItr++;
}
}
if (mapItr == store.end())
return endKey();
else if (count == abs(selector.offset))
return mapItr->first;
else
return startKey();
}
// Gets a range of key-value pairs, returning a maximum of <limit> results
RangeResult MemoryKeyValueStore::getRange(KeyRangeRef range, int limit, Reverse reverse) const {
RangeResult results;
if (!reverse) {
std::map<Key, Value>::const_iterator mapItr = store.lower_bound(range.begin);
for (; mapItr != store.end() && mapItr->first < range.end && results.size() < limit; mapItr++)
results.push_back_deep(results.arena(), KeyValueRef(mapItr->first, mapItr->second));
}
// Support for reverse getRange queries is supported, but not tested at this time. This is because reverse range
// queries have been disallowed by the database at the API level
else {
std::map<Key, Value>::const_iterator mapItr = store.lower_bound(range.end);
if (mapItr == store.begin())
return results;
for (--mapItr; mapItr->first >= range.begin && results.size() < abs(limit); mapItr--) {
results.push_back_deep(results.arena(), KeyValueRef(mapItr->first, mapItr->second));
if (mapItr == store.begin())
break;
}
}
return results;
}
// Stores a key-value pair in the database
void MemoryKeyValueStore::set(KeyRef key, ValueRef value) {
store[key] = value;
}
// Removes a key from the database
void MemoryKeyValueStore::clear(KeyRef key) {
store.erase(key);
}
// Removes a range of keys from the database
void MemoryKeyValueStore::clear(KeyRangeRef range) {
store.erase(store.lower_bound(range.begin), store.lower_bound(range.end));
}
// The number of keys in the database
uint64_t MemoryKeyValueStore::size() const {
return store.size();
}
// The first key in the database; returned by key selectors that choose a key off the front
Key MemoryKeyValueStore::startKey() const {
return LiteralStringRef("");
}
// The last key in the database; returned by key selectors that choose a key off the back
Key MemoryKeyValueStore::endKey() const {
return LiteralStringRef("\xff");
}
// Debugging function that prints all key-value pairs
void MemoryKeyValueStore::printContents() const {
printf("Contents:\n");
std::map<Key, Value>::const_iterator mapItr;
for (mapItr = store.begin(); mapItr != store.end(); mapItr++)
printf("%s\n", mapItr->first.toString().c_str());
}