wangle::LRUInMemoryCache< K, V, MutexT > Class Template Reference

#include <LRUInMemoryCache.h>

Public Member Functions
	LRUInMemoryCache (size_t capacity)
	~LRUInMemoryCache ()=default
folly::Optional< V >	get (const K &key)
void	put (const K &key, const V &val)
bool	remove (const K &key)
size_t	size () const
void	clear ()
CacheDataVersion	getVersion () const
CacheDataVersion	loadData (const folly::dynamic &kvPairs) noexcept
folly::Optional< std::pair< folly::dynamic, CacheDataVersion > >	convertToKeyValuePairs () noexcept
bool	hasChangedSince (CacheDataVersion version) const

Private Member Functions
void	incrementVersion ()

Private Attributes
folly::EvictingCacheMap< K, V >	cache_
CacheDataVersion	version_ {1}
MutexT	cacheLock_

Detailed Description

template<typename K, typename V, typename MutexT>
class wangle::LRUInMemoryCache< K, V, MutexT >

A threadsafe cache map that delegates to an EvictingCacheMap and maintains a version of the data.

Definition at line 32 of file LRUInMemoryCache.h.

Constructor & Destructor Documentation

template<typename K, typename V, typename MutexT>

wangle::LRUInMemoryCache< K, V, MutexT >::LRUInMemoryCache ( size_t  capacity )

inlineexplicit

Create with the specified capacity.

Definition at line 37 of file LRUInMemoryCache.h.

: cache_(capacity) {}

template<typename K, typename V, typename MutexT>

wangle::LRUInMemoryCache< K, V, MutexT >::~LRUInMemoryCache ( )

default

Referenced by wangle::LRUInMemoryCache< K, V, M >::LRUInMemoryCache().

Member Function Documentation

template<typename K , typename V , typename M >

void wangle::LRUInMemoryCache< K, V, M >::clear

(

)

Definition at line 59 of file LRUInMemoryCache-inl.h.

Referenced by wangle::LRUInMemoryCache< K, V, M >::LRUInMemoryCache().

                                      {
  typename wangle::CacheLockGuard<M>::Write writeLock(cacheLock_);
  if (cache_.empty()) {
    return;
  }
  cache_.clear();
  incrementVersion();
}

template<typename K , typename V , typename M >

folly::Optional< std::pair< folly::dynamic, CacheDataVersion > > wangle::LRUInMemoryCache< K, V, M >::convertToKeyValuePairs ( )

noexcept

Get the cache data as a list of kv pairs along with the version

Definition at line 105 of file LRUInMemoryCache-inl.h.

References folly::dynamic::array(), folly::gen::move, folly::none, folly::dynamic::push_back(), and folly::toDynamic().

Referenced by wangle::LRUInMemoryCache< K, V, M >::LRUInMemoryCache().

                                                           {
  typename wangle::CacheLockGuard<M>::Read readLock(cacheLock_);
  try {
    folly::dynamic dynObj = folly::dynamic::array;
    for (const auto& kv : cache_) {
      dynObj.push_back(folly::toDynamic(std::make_pair(kv.first, kv.second)));
    }
    return std::make_pair(std::move(dynObj), version_);
  } catch (const std::exception& err) {
    LOG(ERROR) << "Converting cache to folly::dynamic failed with error: "
               << err.what();
  }
  return folly::none;
}

template<typename K, typename V , typename M >

folly::Optional< V > wangle::LRUInMemoryCache< K, V, M >::get

(

const K &

key

)

Definition at line 24 of file LRUInMemoryCache-inl.h.

References folly::none.

                                                            {
  // need to take a write lock since get modifies the LRU
  typename wangle::CacheLockGuard<M>::Write writeLock(cacheLock_);
  auto itr = cache_.find(key);
  if (itr != cache_.end()) {
    return folly::Optional<V>(itr->second);
  }
  return folly::none;
}

template<typename K , typename V , typename M >

CacheDataVersion wangle::LRUInMemoryCache< K, V, M >::getVersion

(

)

const

Definition at line 69 of file LRUInMemoryCache-inl.h.

Referenced by wangle::LRUInMemoryCache< K, V, M >::hasChangedSince(), and wangle::LRUInMemoryCache< K, V, M >::LRUInMemoryCache().

                                                             {
  typename wangle::CacheLockGuard<M>::Read readLock(cacheLock_);
  return version_;
}

template<typename K, typename V, typename MutexT>

bool wangle::LRUInMemoryCache< K, V, MutexT >::hasChangedSince ( CacheDataVersion  version ) const

inline

Determine if the cache has changed since the specified version

Definition at line 63 of file LRUInMemoryCache.h.

                                                       {
    return getVersion() != version;
  }

template<typename K, typename V, typename MutexT>

void wangle::LRUInMemoryCache< K, V, MutexT >::incrementVersion ( )

inlineprivate

Definition at line 70 of file LRUInMemoryCache.h.

                          {
    ++version_;
    // if a uint64_t is incremented a billion times a second, it will still take
    // 585 years to wrap around, so don't bother
  }

template<typename K , typename V , typename M >

CacheDataVersion wangle::LRUInMemoryCache< K, V, M >::loadData ( const folly::dynamic &  kvPairs )

noexcept

Loads the list of kv pairs into the cache and bumps version. Returns the new cache version.

Definition at line 76 of file LRUInMemoryCache-inl.h.

References data.

Referenced by wangle::LRUInMemoryCache< K, V, M >::LRUInMemoryCache().

                                                                     {
  bool updated = false;
  typename wangle::CacheLockGuard<M>::Write writeLock(cacheLock_);
  try {
    for (const auto& kv : data) {
      cache_.set(
        folly::convertTo<K>(kv[0]),
        folly::convertTo<V>(kv[1]));
      updated = true;
    }
  } catch (const folly::TypeError& err) {
    LOG(ERROR) << "Load cache failed with type error: "
                << err.what();
  } catch (const std::out_of_range& err) {
    LOG(ERROR) << "Load cache failed with key error: "
                << err.what();
  } catch (const std::exception& err) {
    LOG(ERROR) << "Load cache failed with error: "
                << err.what();
  }
  if (updated) {
    // we still need to increment the version
    incrementVersion();
  }
  return version_;
}

template<typename K, typename V, typename M >

void wangle::LRUInMemoryCache< K, V, M >::put	(	const K &	key,
		const V &	val
	)

Definition at line 35 of file LRUInMemoryCache-inl.h.

Referenced by wangle::LRUInMemoryCache< K, V, M >::LRUInMemoryCache().

                                                              {
  typename wangle::CacheLockGuard<M>::Write writeLock(cacheLock_);
  cache_.set(key, val);
  incrementVersion();
}

template<typename K, typename V , typename M >

bool wangle::LRUInMemoryCache< K, V, M >::remove

(

const K &

key

)

Definition at line 42 of file LRUInMemoryCache-inl.h.

                                                   {
  typename wangle::CacheLockGuard<M>::Write writeLock(cacheLock_);
  size_t nErased = cache_.erase(key);
  if (nErased > 0) {
    incrementVersion();
    return true;
  }
  return false;
}

template<typename K , typename V , typename M >

size_t wangle::LRUInMemoryCache< K, V, M >::size

(

)

const

Definition at line 53 of file LRUInMemoryCache-inl.h.

Referenced by wangle::LRUInMemoryCache< K, V, M >::LRUInMemoryCache().

                                             {
  typename wangle::CacheLockGuard<M>::Read readLock(cacheLock_);
  return cache_.size();
}

Member Data Documentation

template<typename K, typename V, typename MutexT>

folly::EvictingCacheMap<K, V> wangle::LRUInMemoryCache< K, V, MutexT >::cache_

private

Definition at line 76 of file LRUInMemoryCache.h.

template<typename K, typename V, typename MutexT>

MutexT wangle::LRUInMemoryCache< K, V, MutexT >::cacheLock_

mutableprivate

Definition at line 80 of file LRUInMemoryCache.h.

template<typename K, typename V, typename MutexT>

CacheDataVersion wangle::LRUInMemoryCache< K, V, MutexT >::version_ {1}

private

Definition at line 78 of file LRUInMemoryCache.h.

Referenced by wangle::LRUInMemoryCache< K, V, M >::incrementVersion().

---

The documentation for this class was generated from the following files:

• proxygen/wangle/wangle/client/persistence/LRUInMemoryCache.h
• proxygen/wangle/wangle/client/persistence/LRUInMemoryCache-inl.h