Package com.google.appengine.api.memcache

Provides fast but unreliable data storage, also accessible via a JCache interface. Objects may be stored in the cache with an explicit expiration time, but may also be evicted before that expiration to make room for newer, more active entries.

The cache is accessed via a MemcacheService object, obtained from the MemcacheServiceFactory. It offers the cache as a map from key Object to value Object.

In the Development Server, the system property memcache.maxsize can be set to limit the available cache, taking values like "100M" (the default), "10K", or "768" (bytes).

Because the cache offers best-effort data storage, by default most errors are treated as a cache miss. More explicit error handling can be installed via BaseMemcacheService.setErrorHandler(ErrorHandler).

See Also:

MemcacheService, The Memcache Java API in the Google App Engine Developer's Guide., JCache API

Interface Summary

Interface	Description
AsyncMemcacheService	An asynchronous version of MemcacheService.
BaseMemcacheService	Methods that are common between MemcacheService and AsyncMemcacheService.
ConsistentErrorHandler	A marker interface to indicate that all MemcacheServiceException exceptions should be handled by ErrorHandler.handleServiceError(MemcacheServiceException).
ErrorHandler	Handles errors raised by the MemcacheService, registered with BaseMemcacheService.setErrorHandler(ErrorHandler).
IMemcacheServiceFactory	The factory by which users acquire a handle to the MemcacheService.
MemcacheService	The Java API for the App Engine Memcache service.
MemcacheService.IdentifiableValue	Encapsulates an Object that is returned by MemcacheService.getIdentifiable(java.lang.Object).
Stats	Statistics from the cache, available via MemcacheService.getStatistics()

Class Summary

Class	Description
ConsistentLogAndContinueErrorHandler	Similar to the deprecated LogAndContinueErrorHandler but consistently handles all back-end related errors.
ErrorHandlers	Static utility for getting built-in ErrorHandlers.
Expiration	Expiration specifications on MemcacheService.putAll(Map , Expiration) and MemcacheService.put(Object, Object, Expiration) operations.
IMemcacheServiceFactoryProvider	Factory provider for IMemcacheServiceFactory.
LogAndContinueErrorHandler	The default error handler, which will cause most service errors to behave as though there were a cache miss, not an error.
MemcacheSerialization	Static serialization helpers used by MemcacheServiceImpl This class is thread-safe.
MemcacheSerialization.ValueAndFlags	Tuple of a serialized byte array value and associated flags to interpret that value.
MemcacheService.CasValues	A holder for compare and set values.
MemcacheServiceFactory	The factory by which users acquire a handle to the MemcacheService.
StrictErrorHandler	A strict error handler, which will throw MemcacheServiceException or InvalidValueException for any service error condition.

Enum Summary

Enum	Description
MemcacheSerialization.Flag	Values used as flags on the MemcacheService's values.
MemcacheService.SetPolicy	Cache replacement strategies for MemcacheService.put(java.lang.Object, java.lang.Object, com.google.appengine.api.memcache.Expiration, com.google.appengine.api.memcache.MemcacheService.SetPolicy) operations, indicating how to handle putting a value that already exists.

Exception Summary

Exception	Description
InvalidValueException	Thrown when a cache entry has content, but it cannot be read.
MemcacheServiceException	An exception for backend non-availability or similar error states which may occur, but are not necessarily indicative of a coding or usage error by the application.