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This package define Dart interfaces for memcache. The package defines both a high-level interface and a low-level interface.

These interfaces are used for the memcache support in the appengine package. Therefore these interfaces only support the memcache operations supported by App Engine.

The high-level interface is called Memcache. It provides a Future based API for the most common access patterns. It defaults to use String values for both keys and values. Store and retrieve single values:

Memcache memcache = ...
memcache.set('MyKey', 'MyValue').then((_) {
  memcache.get('MyKey').then((String value) {
    // value is read from memcache.
  });
});

Store and retrieve multiple values:

Memcache memcache = ...
memcache.setAll({'MyKey1': 'MyValue1',
                 'MyKey2': 'MyValue2').then((_) {
  memcache.getAll(['MyKey1', 'MyKey2']).then((Map result) {
    // result is a map with the values for MyKey1 and MyKey2.
  });
});

The high-level interface does not expose the CAS values directly. However through the withCAS method, it becomes simple to use CAS with memcache operations. withCAS returns an implemetation of Memcache which internally keeps track of the CAS for all keys retrieved. When a key is stored the CAS value from when it was retrieved, will be passed automatically to memcache.

Memcache memcache = ...
Memcache cas = memcache.withCAS();
cas.get('MyKey').then((value) {
  memcache.set('MyKey', 'MyNewValue').then((_) {
    // MyNewValue is stored in memcache if the CAS did not
    // change from when it was retrieved.
  });
});

The low-level interface is called RawMemcache and provides a generic interface using request/response objects send in batches to memcache.

In a Dart App Engine application using the appengine package the memcahce interface is available on the client context.

context.services.memcache.get('MyKey').then(String value) => ...

This package will also provide an implementation of the native memcached protocol. This is still work in progress, and it will support the interfaces defined in this package.