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

Class MemcachedHttpCacheStorage

java.lang.Object

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

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

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

All Implemented Interfaces:

HttpCacheStorage

public class MemcachedHttpCacheStorage
extends AbstractBinaryCacheStorage<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:

4.1

Constructor Summary

Constructors

Constructor and Description
MemcachedHttpCacheStorage(InetSocketAddress address) Create a storage backend talking to a memcached instance listening on the specified host and port.
MemcachedHttpCacheStorage(net.spy.memcached.MemcachedClient cache) Create a storage backend using the pre-configured given memcached client.
MemcachedHttpCacheStorage(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.
MemcachedHttpCacheStorage(net.spy.memcached.MemcachedClientIF cache) Create a storage backend using the pre-configured given memcached client.
MemcachedHttpCacheStorage(net.spy.memcached.MemcachedClientIF 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 Map<String,byte[]>	bulkRestore(Collection<String> storageKeys)
protected void	delete(String storageKey)
protected String	digestToStorageKey(String key)
protected net.spy.memcached.CASValue<Object>	getForUpdateCAS(String storageKey)
protected byte[]	getStorageObject(net.spy.memcached.CASValue<Object> casValue)
protected byte[]	restore(String storageKey)
protected void	store(String storageKey, byte[] storageObject)
protected boolean	updateCAS(String storageKey, net.spy.memcached.CASValue<Object> casValue, byte[] storageObject)

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

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

MemcachedHttpCacheStorage

public MemcachedHttpCacheStorage(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

MemcachedHttpCacheStorage

public MemcachedHttpCacheStorage(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

MemcachedHttpCacheStorage

public MemcachedHttpCacheStorage(net.spy.memcached.MemcachedClientIF cache)

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

Parameters:

cache - client to use for communicating with memcached

Since:

5.2

MemcachedHttpCacheStorage

public MemcachedHttpCacheStorage(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

MemcachedHttpCacheStorage

public MemcachedHttpCacheStorage(net.spy.memcached.MemcachedClientIF 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

Since:

5.2

Method Detail

digestToStorageKey

protected String digestToStorageKey(String key)

Specified by:

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

store

protected void store(String storageKey,
                     byte[] storageObject)
              throws ResourceIOException

Specified by:

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

Throws:

ResourceIOException

restore

protected byte[] restore(String storageKey)
                  throws ResourceIOException

Specified by:

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

Throws:

ResourceIOException

getForUpdateCAS

protected net.spy.memcached.CASValue<Object> getForUpdateCAS(String storageKey)
                                                      throws ResourceIOException

Specified by:

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

Throws:

ResourceIOException

getStorageObject

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

Specified by:

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

Throws:

ResourceIOException

updateCAS

protected boolean updateCAS(String storageKey,
                            net.spy.memcached.CASValue<Object> casValue,
                            byte[] storageObject)
                     throws ResourceIOException

Specified by:

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

Throws:

ResourceIOException

delete

protected void delete(String storageKey)
               throws ResourceIOException

Specified by:

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

Throws:

ResourceIOException

bulkRestore

protected Map<String,byte[]> bulkRestore(Collection<String> storageKeys)
                                  throws ResourceIOException

Specified by:

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

Throws:

ResourceIOException