Package com.google.appengine.api.memcache

Interface ErrorHandler

All Known Subinterfaces:
ConsistentErrorHandler
All Known Implementing Classes:
ConsistentLogAndContinueErrorHandler, LogAndContinueErrorHandler, StrictErrorHandler
public interface ErrorHandler
Handles errors raised by the MemcacheService, registered with BaseMemcacheService.setErrorHandler(ErrorHandler).

The default error handler is an instance of LogAndContinueErrorHandler. In most cases, this will log exceptions without throwing, which looks like a cache-miss behavior to the caller. A less permissive alternative is StrictErrorHandler, which will throw a MemcacheServiceException to surface errors to callers.

To guarantee that all instances of MemcacheServiceException are directed to the error handler, use a ConsistentErrorHandler such as ErrorHandlers.getConsistentLogAndContinue(Level) or ErrorHandlers.getStrict().

  • Method Details

    • handleDeserializationError

      void handleDeserializationError(InvalidValueException ivx)
      Handles deserialization errors. This method is called from either of the get methods, if the retrieved value cannot be deserialized. This normally indicates an application upgrade since the cache entry was stored, and should thus be treated as a cache miss, which is the behavior of LogAndContinueErrorHandler (the default).

    • handleServiceError

      void handleServiceError(MemcacheServiceException ex)
      Handles back-end service errors. This method is called from most of the MemcacheService methods in the event of a service error. This is also called for MemcacheService.put(Object, Object) when the combined key and value size is too large.

      The handler may throw any RuntimeException, or it may simply return for "permissive" error handling, which will generally emulate behavior of a cache miss due to a discarded entry.

      Parameters:
      ex - the service error exception