#include "lru_cache.h"

Inheritance diagram for net_instaweb::LRUCache:

Public Member Functions
	LRUCache (size_t max_size)

virtual void	Get (const GoogleString &key, Callback *callback)

virtual void	Put (const GoogleString &key, const SharedString &new_value)

virtual void	Delete (const GoogleString &key)

void	DeleteWithPrefixForTesting (StringPiece prefix)

size_t	size_bytes () const
	Total size in bytes of keys and values stored.

size_t	max_bytes_in_cache () const
	Maximum capacity.

size_t	num_elements () const
	Number of elements stored.

size_t	num_evictions () const

size_t	num_hits () const

size_t	num_misses () const

size_t	num_inserts () const

size_t	num_identical_reinserts () const

size_t	num_deletes () const

void	SanityCheck ()
	Sanity check the cache data structures.

void	Clear ()

void	ClearStats ()
	Clear the stats – note that this will not clear the content.

virtual GoogleString	Name () const

virtual bool	IsBlocking () const

virtual bool	IsHealthy () const

virtual void	ShutDown ()

void	set_is_healthy (bool x)

Public Member Functions inherited from net_instaweb::CacheInterface
virtual void	MultiGet (MultiGetRequest *request)

void	PutSwappingString (const GoogleString &key, GoogleString *value)

virtual CacheInterface *	Backend ()

virtual bool	MustEncodeKeyInValueOnPut () const

virtual void	PutWithKeyInValue (const GoogleString &key, const SharedString &key_and_value)

Static Public Member Functions
static GoogleString	FormatName ()

Static Public Member Functions inherited from net_instaweb::CacheInterface
static const char *	KeyStateName (KeyState state)

Additional Inherited Members
Public Types inherited from net_instaweb::CacheInterface
enum	KeyState { kAvailable = 0, kNotFound = 1, kOverload = 2, kNetworkError = 3, kTimeout = 4 }

typedef std::vector< KeyCallback >	MultiGetRequest

Protected Member Functions inherited from net_instaweb::CacheInterface
void	ValidateAndReportResult (const GoogleString &key, KeyState state, Callback *callback)
	Invokes callback->ValidateCandidate() and callback->Done() as appropriate.

void	ReportMultiGetNotFound (MultiGetRequest *request)

Detailed Description

Simple C++ implementation of an in-memory least-recently used (LRU) cache. This implementation is not thread-safe, and must be combined with a mutex to make it so.

The purpose of this implementation is as a default implementation, or an local shadow for memcached.

Also of note: the Get interface allows for streaming. To get into a GoogleString, use a StringWriter.

Todo:: TODO(jmarantz): The Put interface does not currently stream, but this should be added.

Member Function Documentation

void net_instaweb::LRUCache::Clear ( )

inline

Clear the entire cache. Used primarily for testing. Note that this will not clear the stats, however it will update current_bytes_in_cache_.

void net_instaweb::LRUCache::DeleteWithPrefixForTesting ( StringPiece prefix )

Deletes all objects whose key starts with prefix. Not part of cache interface. Exported for testing only.

virtual void net_instaweb::LRUCache::Get	(	const GoogleString &	key,
		Callback *	callback
	)

virtual

Initiates a cache fetch, calling callback->ValidateCandidate() and then callback->Done(state) when done.

Note: implementations should normally invoke the callback via ValidateAndReportResult, which will combine ValidateCandidate() and Done() together properly.

Implements net_instaweb::CacheInterface.

virtual bool net_instaweb::LRUCache::IsBlocking ( ) const

inlinevirtual

Returns true if this cache is guaranteed to call its callbacks before returning from Get and MultiGet.

Implements net_instaweb::CacheInterface.

virtual bool net_instaweb::LRUCache::IsHealthy ( ) const

inlinevirtual

IsHealthy() is a rough estimation of whether cache is available for any operations. If it's false, caller may reasonably expect that making calls right now is useless as they will fail or have high latency. If it's true, operations should succeed, but some still may fail occasionally. The primary goal is to avoid sending commands to 'unhealthy' caches, e.g. if cache is under heavy load, we do not want to send even more requests.

Memory and file-based caches can simply return 'true'. It should be safe to call this frequently – the implementation shouldn't do much more that check a bool flag under mutex.

Implements net_instaweb::CacheInterface.

virtual GoogleString net_instaweb::LRUCache::Name ( ) const

inlinevirtual

The name of this CacheInterface – used for logging and debugging.

It is strongly recommended that you provide a static GoogleString FormatName(...) method for use in formatting the Name() return, and in testing, e.g. in third_party/pagespeed/system/system_caches_test.cc.

Implements net_instaweb::CacheInterface.

virtual void net_instaweb::LRUCache::Put	(	const GoogleString &	key,
		const SharedString &	new_value
	)

virtual

Puts an object into the cache, sharing the bytes.

Todo:: TODO(jmarantz): currently if the caller mutates the SharedString after having called Put, it will actually modify the value in the cache. We should change SharedString to Copy-On-Write semantics.

Implements net_instaweb::CacheInterface.

virtual void net_instaweb::LRUCache::ShutDown ( )

inlinevirtual

Stops all cache activity. Further Put/Delete calls will be dropped, and MultiGet/Get will call the callback with kNotFound immediately. Note there is no Enable(); once the cache is stopped it is stopped forever. This function is intended for use during process shutdown.

Implements net_instaweb::CacheInterface.

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

pagespeed/kernel/cache/lru_cache.h

Public Member Functions

Static Public Member Functions

Additional Inherited Members

Detailed Description

Member Function Documentation