org.apache.hc.client5.http.impl.cache.memcached

Class MemcachedHttpAsyncCacheStorage

java.lang.Object

org.apache.hc.client5.http.impl.cache.AbstractSerializingAsyncCacheStorage<byte[],CAS>

org.apache.hc.client5.http.impl.cache.AbstractBinaryAsyncCacheStorage<net.spy.memcached.CASValue<Object>>

org.apache.hc.client5.http.impl.cache.memcached.MemcachedHttpAsyncCacheStorage

All Implemented Interfaces:

HttpAsyncCacheStorage

public class MemcachedHttpAsyncCacheStorage
extends AbstractBinaryAsyncCacheStorage<net.spy.memcached.CASValue<Object>>

This class is a storage backend that uses an external memcached for storing cached origin responses. This storage option provides a couple of interesting advantages over the default in-memory storage backend:

1. in-memory cached objects can survive an application restart since they are held in a separate process
2. it becomes possible for several cooperating applications to share a large memcached farm together

Note that in a shared memcached pool setting you may wish to make use of the Ketama consistent hashing algorithm to reduce the number of cache misses that might result if one of the memcached cluster members fails (see the KetamaConnectionFactory).

Because memcached places limits on the size of its keys, we need to introduce a key hashing scheme to map the annotated URLs the higher-level caching HTTP client wants to use as keys onto ones that are suitable for use with memcached. Please see KeyHashingScheme if you would like to use something other than the provided SHA256KeyHashingScheme.

Please refer to the memcached documentation and in particular to the documentation for the spymemcached documentation for details about how to set up and configure memcached and the Java client used here, respectively.

Since:

5.0

Constructor Summary

Constructors

Constructor and Description
MemcachedHttpAsyncCacheStorage(InetSocketAddress address) Create a storage backend talking to a memcached instance listening on the specified host and port.
MemcachedHttpAsyncCacheStorage(net.spy.memcached.MemcachedClient cache) Create a storage backend using the pre-configured given memcached client.
MemcachedHttpAsyncCacheStorage(net.spy.memcached.MemcachedClient client, CacheConfig config, HttpCacheEntrySerializer<byte[]> serializer, KeyHashingScheme keyHashingScheme) Create a storage backend using the given memcached client and applying the given cache configuration, serialization, and hashing mechanisms.

Method Summary

Modifier and Type	Method and Description
protected org.apache.hc.core5.concurrent.Cancellable	bulkRestore(Collection<String> storageKeys, org.apache.hc.core5.concurrent.FutureCallback<Map<String,byte[]>> callback)
protected org.apache.hc.core5.concurrent.Cancellable	delete(String storageKey, org.apache.hc.core5.concurrent.FutureCallback<Boolean> callback)
protected String	digestToStorageKey(String key)
protected org.apache.hc.core5.concurrent.Cancellable	getForUpdateCAS(String storageKey, org.apache.hc.core5.concurrent.FutureCallback<net.spy.memcached.CASValue<Object>> callback)
protected byte[]	getStorageObject(net.spy.memcached.CASValue<Object> casValue)
protected org.apache.hc.core5.concurrent.Cancellable	restore(String storageKey, org.apache.hc.core5.concurrent.FutureCallback<byte[]> callback)
protected org.apache.hc.core5.concurrent.Cancellable	store(String storageKey, byte[] storageObject, org.apache.hc.core5.concurrent.FutureCallback<Boolean> callback)
protected org.apache.hc.core5.concurrent.Cancellable	updateCAS(String storageKey, net.spy.memcached.CASValue<Object> casValue, byte[] storageObject, org.apache.hc.core5.concurrent.FutureCallback<Boolean> callback)

Methods inherited from class org.apache.hc.client5.http.impl.cache.AbstractSerializingAsyncCacheStorage

getEntries, getEntry, putEntry, removeEntry, updateEntry

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

MemcachedHttpAsyncCacheStorage

public MemcachedHttpAsyncCacheStorage(InetSocketAddress address)
                               throws IOException

Create a storage backend talking to a memcached instance listening on the specified host and port. This is useful if you just have a single local memcached instance running on the same machine as your application, for example.

Parameters:

address - where the memcached daemon is running

Throws:

IOException - in case of an error

MemcachedHttpAsyncCacheStorage

public MemcachedHttpAsyncCacheStorage(net.spy.memcached.MemcachedClient cache)

Create a storage backend using the pre-configured given memcached client.

Parameters:

cache - client to use for communicating with memcached

MemcachedHttpAsyncCacheStorage

public MemcachedHttpAsyncCacheStorage(net.spy.memcached.MemcachedClient client,
                                      CacheConfig config,
                                      HttpCacheEntrySerializer<byte[]> serializer,
                                      KeyHashingScheme keyHashingScheme)

Create a storage backend using the given memcached client and applying the given cache configuration, serialization, and hashing mechanisms.

Parameters:

client - how to talk to memcached

config - apply HTTP cache-related options

serializer - alternative serialization mechanism

keyHashingScheme - how to map higher-level logical "storage keys" onto "cache keys" suitable for use with memcached

Method Detail

digestToStorageKey

protected String digestToStorageKey(String key)

Specified by:

digestToStorageKey in class AbstractSerializingAsyncCacheStorage<byte[],net.spy.memcached.CASValue<Object>>

getStorageObject

protected byte[] getStorageObject(net.spy.memcached.CASValue<Object> casValue)
                           throws ResourceIOException

Specified by:

getStorageObject in class AbstractSerializingAsyncCacheStorage<byte[],net.spy.memcached.CASValue<Object>>

Throws:

ResourceIOException

store

protected org.apache.hc.core5.concurrent.Cancellable store(String storageKey,
                                                           byte[] storageObject,
                                                           org.apache.hc.core5.concurrent.FutureCallback<Boolean> callback)

Specified by:

store in class AbstractSerializingAsyncCacheStorage<byte[],net.spy.memcached.CASValue<Object>>

restore

protected org.apache.hc.core5.concurrent.Cancellable restore(String storageKey,
                                                             org.apache.hc.core5.concurrent.FutureCallback<byte[]> callback)

Specified by:

restore in class AbstractSerializingAsyncCacheStorage<byte[],net.spy.memcached.CASValue<Object>>

getForUpdateCAS

protected org.apache.hc.core5.concurrent.Cancellable getForUpdateCAS(String storageKey,
                                                                     org.apache.hc.core5.concurrent.FutureCallback<net.spy.memcached.CASValue<Object>> callback)

Specified by:

getForUpdateCAS in class AbstractSerializingAsyncCacheStorage<byte[],net.spy.memcached.CASValue<Object>>

updateCAS

protected org.apache.hc.core5.concurrent.Cancellable updateCAS(String storageKey,
                                                               net.spy.memcached.CASValue<Object> casValue,
                                                               byte[] storageObject,
                                                               org.apache.hc.core5.concurrent.FutureCallback<Boolean> callback)

Specified by:

updateCAS in class AbstractSerializingAsyncCacheStorage<byte[],net.spy.memcached.CASValue<Object>>

delete

protected org.apache.hc.core5.concurrent.Cancellable delete(String storageKey,
                                                            org.apache.hc.core5.concurrent.FutureCallback<Boolean> callback)

Specified by:

delete in class AbstractSerializingAsyncCacheStorage<byte[],net.spy.memcached.CASValue<Object>>

bulkRestore

protected org.apache.hc.core5.concurrent.Cancellable bulkRestore(Collection<String> storageKeys,
                                                                 org.apache.hc.core5.concurrent.FutureCallback<Map<String,byte[]>> callback)

Specified by:

bulkRestore in class AbstractSerializingAsyncCacheStorage<byte[],net.spy.memcached.CASValue<Object>>