57 lines
1.6 KiB
C++
57 lines
1.6 KiB
C++
#ifndef CONCURRENT_ID_MAP_HPP
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#define CONCURRENT_ID_MAP_HPP
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#include <boost/interprocess/sync/interprocess_upgradable_mutex.hpp>
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#include <boost/interprocess/sync/scoped_lock.hpp>
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#include <boost/interprocess/sync/sharable_lock.hpp>
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#include <unordered_map>
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namespace osrm
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{
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namespace util
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{
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/**
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* This is a special purpose map for caching incrementing IDs
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*/
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template <typename KeyType, typename ValueType, typename HashType = std::hash<KeyType>>
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struct ConcurrentIDMap
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{
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static_assert(std::is_unsigned<ValueType>::value, "Only unsigned integer types are supported.");
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using UpgradableMutex = boost::interprocess::interprocess_upgradable_mutex;
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using ScopedReaderLock = boost::interprocess::sharable_lock<UpgradableMutex>;
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using ScopedWriterLock = boost::interprocess::scoped_lock<UpgradableMutex>;
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std::unordered_map<KeyType, ValueType, HashType> data;
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mutable UpgradableMutex mutex;
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const ValueType ConcurrentFindOrAdd(const KeyType &key)
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{
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{
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ScopedReaderLock sentry{mutex};
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const auto result = data.find(key);
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if (result != data.end())
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{
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return result->second;
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}
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}
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{
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ScopedWriterLock sentry{mutex};
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const auto result = data.find(key);
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if (result != data.end())
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{
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return result->second;
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}
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const auto id = static_cast<ValueType>(data.size());
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data[key] = id;
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return id;
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}
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}
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};
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} // util
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} // osrm
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#endif // CONCURRENT_ID_MAP_HPP
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