.. _program_listing_file_src_translator_cache.h:

Program Listing for File cache.h
================================

|exhale_lsh| :ref:`Return to documentation for file <file_src_translator_cache.h>` (``src/translator/cache.h``)

.. |exhale_lsh| unicode:: U+021B0 .. UPWARDS ARROW WITH TIP LEFTWARDS

.. code-block:: cpp

   #pragma once
   #include <atomic>
   #include <memory>
   #include <mutex>
   #include <vector>
   
   #include "definitions.h"
   #include "translator/history.h"
   
   namespace marian::bergamot {
   
   template <class Key, class Value, class Hash = std::hash<Key>, class Equals = std::equal_to<Key>>
   class AtomicCache {
    public:
     struct Stats {
       size_t hits{0};
       size_t misses{0};
     };
   
     explicit AtomicCache(size_t size, size_t buckets) : records_(size), mutexBuckets_(buckets) {}
   
     std::pair<bool, Value> find(const Key &key) const {
       Value value;
       bool found = atomicLoad(key, value);
       return std::make_pair(found, value);
     }
   
     void store(const Key &key, Value value) { atomicStore(key, value); }
   
     const Stats stats() const {
   #ifdef ENABLE_CACHE_STATS
       return Stats{hits_.load(), misses_.load()};
   #else
       ABORT("Cache statistics requested without enabling in builds. Please use -DENABLE_CACHE_STATS with cmake.");
       return Stats{0, 0};
   #endif
     }
   
    private:
     using Record = std::pair<Key, Value>;
   
     bool atomicLoad(const Key &key, Value &value) const {
       // No probing, direct map onto records_
       size_t index = hash_(key) % records_.size();
       size_t mutexId = index % mutexBuckets_.size();
   
       std::lock_guard<std::mutex> lock(mutexBuckets_[mutexId]);
       const Record &candidate = records_[index];
       if (equals_(key, candidate.first)) {
         value = candidate.second;
   #ifdef ENABLE_CACHE_STATS
         ++hits_;
   #endif
         return true;
       } else {
   #ifdef ENABLE_CACHE_STATS
         ++misses_;
   #endif
       }
   
       return false;
     }
   
     void atomicStore(const Key &key, Value value) {
       // No probing, direct map onto records_
       size_t index = hash_(key) % records_.size();
       size_t mutexId = index % mutexBuckets_.size();
   
       std::lock_guard<std::mutex> lock(mutexBuckets_[mutexId]);
       Record &candidate = records_[index];
   
       candidate.first = key;
       candidate.second = value;
     }
   
     std::vector<Record> records_;
   
     mutable std::vector<std::mutex> mutexBuckets_;
   
   #ifdef ENABLE_CACHE_STATS
     mutable std::atomic<size_t> hits_{0};
     mutable std::atomic<size_t> misses_{0};
   #endif
   
     Hash hash_;
     Equals equals_;
   };
   
   typedef AtomicCache<size_t, Ptr<History>> TranslationCache;
   
   }  // namespace marian::bergamot