| <?xml version="1.0" encoding="UTF-8"?> |
| <!-- |
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| distributed under the License is distributed on an "AS IS" BASIS, |
| WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
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| --> |
| <!-- |
| CacheManager Configuration |
| ========================== |
| An ehcache.xml corresponds to a single CacheManager. |
| |
| See instructions below or the ehcache schema (ehcache.xsd) on how to configure. |
| |
| System property tokens can be specified in this file which are replaced when the configuration |
| is loaded. For example multicastGroupPort=${multicastGroupPort} can be replaced with the |
| System property either from an environment variable or a system property specified with a |
| command line switch such as -DmulticastGroupPort=4446. Another example, useful for Terracotta |
| server based deployments is <terracottaConfig url="${serverAndPort}"/ and specify a command line |
| switch of -Dserver36:9510 |
| |
| The attributes of <ehcache> are: |
| * name - an optional name for the CacheManager. The name is optional and primarily used |
| for documentation or to distinguish Terracotta clustered cache state. With Terracotta |
| clustered caches, a combination of CacheManager name and cache name uniquely identify a |
| particular cache store in the Terracotta clustered memory. |
| * updateCheck - an optional boolean flag specifying whether this CacheManager should check |
| for new versions of Ehcache over the Internet. If not specified, updateCheck="true". |
| * dynamicConfig - an optional setting that can be used to disable dynamic configuration of caches |
| associated with this CacheManager. By default this is set to true - i.e. dynamic configuration |
| is enabled. Dynamically configurable caches can have their TTI, TTL and maximum disk and |
| in-memory capacity changed at runtime through the cache's configuration object. |
| * monitoring - an optional setting that determines whether the CacheManager should |
| automatically register the SampledCacheMBean with the system MBean server. |
| |
| Currently, this monitoring is only useful when using Terracotta clustering and using the |
| Terracotta Developer Console. With the "autodetect" value, the presence of Terracotta clustering |
| will be detected and monitoring, via the Developer Console, will be enabled. Other allowed values |
| are "on" and "off". The default is "autodetect". This setting does not perform any function when |
| used with JMX monitors. |
| |
| * maxBytesLocalHeap - optional setting that constraints the memory usage of the Caches managed by the CacheManager |
| to use at most the specified number of bytes of the local VM's heap. |
| * maxBytesLocalOffHeap - optional setting that constraints the offHeap usage of the Caches managed by the CacheManager |
| to use at most the specified number of bytes of the local VM's offHeap memory. |
| * maxBytesLocalDisk - optional setting that constraints the disk usage of the Caches managed by the CacheManager |
| to use at most the specified number of bytes of the local disk. |
| |
| These settings let you define "resource pools", caches will share. For instance setting maxBytesLocalHeap to 100M, will result in |
| all caches sharing 100 MegaBytes of ram. The CacheManager will balance these 100 MB across all caches based on their respective usage |
| patterns. You can allocate a precise amount of bytes to a particular cache by setting the appropriate maxBytes* attribute for that cache. |
| That amount will be subtracted from the CacheManager pools, so that if a cache a specified 30M requirement, the other caches will share |
| the remaining 70M. |
| |
| Also, specifying a maxBytesLocalOffHeap at the CacheManager level will result in overflowToOffHeap to be true by default. If you don't want |
| a specific cache to overflow to off heap, you'll have to set overflowToOffHeap="false" explicitly |
| |
| Here is an example of CacheManager level resource tuning, which will use up to 400M of heap and 2G of offHeap: |
| |
| <ehcache xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" |
| xsi:noNamespaceSchemaLocation="ehcache.xsd" |
| updateCheck="true" monitoring="autodetect" |
| dynamicConfig="true" maxBytesLocalHeap="400M" maxBytesLocalOffHeap="2G"> |
| |
| --> |
| <ehcache name="LDCache" |
| xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" |
| xsi:noNamespaceSchemaLocation="http://ehcache.org/ehcache.xsd" |
| updateCheck="true" monitoring="autodetect" |
| dynamicConfig="true"> |
| |
| |
| |
| <!-- |
| DiskStore configuration |
| ======================= |
| |
| The diskStore element is optional. To turn off disk store path creation, comment out the diskStore |
| element below. |
| |
| Configure it if you have disk persistence enabled for any cache or if you use |
| unclustered indexed search. |
| |
| If it is not configured, and a cache is created which requires a disk store, a warning will be |
| issued and java.io.tmpdir will automatically be used. |
| |
| diskStore has only one attribute - "path". It is the path to the directory where |
| any required disk files will be created. |
| |
| If the path is one of the following Java System Property it is replaced by its value in the |
| running VM. For backward compatibility these should be specified without being enclosed in the ${token} |
| replacement syntax. |
| |
| The following properties are translated: |
| * user.home - User's home directory |
| * user.dir - User's current working directory |
| * java.io.tmpdir - Default temp file path |
| * ehcache.disk.store.dir - A system property you would normally specify on the command line |
| e.g. java -Dehcache.disk.store.dir=/u01/myapp/diskdir ... |
| |
| Subdirectories can be specified below the property e.g. java.io.tmpdir/one |
| |
| --> |
| <diskStore path="java.io.tmpdir"/> |
| |
| |
| <!-- |
| Cache configuration |
| =================== |
| |
| The following attributes are required. |
| |
| name: |
| Sets the name of the cache. This is used to identify the cache. It must be unique. |
| |
| maxEntriesLocalHeap: |
| Sets the maximum number of objects that will be created in memory. 0 = no limit. |
| In practice no limit means Integer.MAX_SIZE (2147483647) unless the cache is distributed |
| with a Terracotta server in which case it is limited by resources. |
| |
| maxEntriesLocalDisk: |
| Sets the maximum number of objects that will be maintained in the DiskStore |
| The default value is zero, meaning unlimited. |
| |
| eternal: |
| Sets whether elements are eternal. If eternal, timeouts are ignored and the |
| element is never expired. |
| |
| The following attributes and elements are optional. |
| |
| overflowToOffHeap: |
| (boolean) This feature is available only in enterprise versions of Ehcache. |
| When set to true, enables the cache to utilize off-heap memory |
| storage to improve performance. Off-heap memory is not subject to Java |
| GC. The default value is false. |
| |
| maxBytesLocalHeap: |
| Defines how many bytes the cache may use from the VM's heap. If a CacheManager |
| maxBytesLocalHeap has been defined, this Cache's specified amount will be |
| subtracted from the CacheManager. Other caches will share the remainder. |
| This attribute's values are given as <number>k|K|m|M|g|G for |
| kilobytes (k|K), megabytes (m|M), or gigabytes (g|G). |
| For example, maxBytesLocalHeap="2g" allots 2 gigabytes of heap memory. |
| If you specify a maxBytesLocalHeap, you can't use the maxEntriesLocalHeap attribute. |
| maxEntriesLocalHeap can't be used if a CacheManager maxBytesLocalHeap is set. |
| |
| Elements put into the cache will be measured in size using net.sf.ehcache.pool.sizeof.SizeOf |
| If you wish to ignore some part of the object graph, see net.sf.ehcache.pool.sizeof.annotations.IgnoreSizeOf |
| |
| maxBytesLocalOffHeap: |
| This feature is available only in enterprise versions of Ehcache. |
| Sets the amount of off-heap memory this cache can use, and will reserve. |
| |
| This setting will set overflowToOffHeap to true. Set explicitly to false to disable overflow behavior. |
| |
| Note that it is recommended to set maxEntriesLocalHeap to at least 100 elements |
| when using an off-heap store, otherwise performance will be seriously degraded, |
| and a warning will be logged. |
| |
| The minimum amount that can be allocated is 128MB. There is no maximum. |
| |
| maxBytesLocalDisk: |
| As for maxBytesLocalHeap, but specifies the limit of disk storage this cache will ever use. |
| |
| timeToIdleSeconds: |
| Sets the time to idle for an element before it expires. |
| i.e. The maximum amount of time between accesses before an element expires |
| Is only used if the element is not eternal. |
| Optional attribute. A value of 0 means that an Element can idle for infinity. |
| The default value is 0. |
| |
| timeToLiveSeconds: |
| Sets the time to live for an element before it expires. |
| i.e. The maximum time between creation time and when an element expires. |
| Is only used if the element is not eternal. |
| Optional attribute. A value of 0 means that and Element can live for infinity. |
| The default value is 0. |
| |
| diskExpiryThreadIntervalSeconds: |
| The number of seconds between runs of the disk expiry thread. The default value |
| is 120 seconds. |
| |
| diskSpoolBufferSizeMB: |
| This is the size to allocate the DiskStore for a spool buffer. Writes are made |
| to this area and then asynchronously written to disk. The default size is 30MB. |
| Each spool buffer is used only by its cache. If you get OutOfMemory errors consider |
| lowering this value. To improve DiskStore performance consider increasing it. Trace level |
| logging in the DiskStore will show if put back ups are occurring. |
| |
| clearOnFlush: |
| whether the MemoryStore should be cleared when flush() is called on the cache. |
| By default, this is true i.e. the MemoryStore is cleared. |
| |
| statistics: |
| Whether to collect statistics. Note that this should be turned on if you are using |
| the Ehcache Monitor. By default statistics is turned off to favour raw performance. |
| To enable set statistics="true" |
| |
| memoryStoreEvictionPolicy: |
| Policy would be enforced upon reaching the maxEntriesLocalHeap limit. Default |
| policy is Least Recently Used (specified as LRU). Other policies available - |
| First In First Out (specified as FIFO) and Less Frequently Used |
| (specified as LFU) |
| |
| copyOnRead: |
| Whether an Element is copied when being read from a cache. |
| By default this is false. |
| |
| copyOnWrite: |
| Whether an Element is copied when being added to the cache. |
| By default this is false. |
| |
| Cache persistence is configured through the persistence sub-element. The attributes of the |
| persistence element are: |
| |
| strategy: |
| Configures the type of persistence provided by the configured cache. This must be one of the |
| following values: |
| |
| * localRestartable - Enables the RestartStore and copies all cache entries (on-heap and/or off-heap) |
| to disk. This option provides fast restartability with fault tolerant cache persistence on disk. |
| It is available for Enterprise Ehcache users only. |
| |
| * localTempSwap - Swaps cache entries (on-heap and/or off-heap) to disk when the cache is full. |
| "localTempSwap" is not persistent. |
| |
| * none - Does not persist cache entries. |
| |
| * distributed - Defers to the <terracotta> configuration for persistence settings. This option |
| is not applicable for standalone. |
| |
| synchronousWrites: |
| When set to true write operations on the cache do not return until after the operations data has been |
| successfully flushed to the disk storage. This option is only valid when used with the "localRestartable" |
| strategy, and defaults to false. |
| |
| The following example configuration shows a cache configured for localTempSwap restartability. |
| |
| <cache name="persistentCache" maxEntriesLocalHeap="1000"> |
| <persistence strategy="localTempSwap"/> |
| </cache> |
| |
| Cache elements can also contain sub elements which take the same format of a factory class |
| and properties. Defined sub-elements are: |
| |
| * cacheEventListenerFactory - Enables registration of listeners for cache events, such as |
| put, remove, update, and expire. |
| |
| * bootstrapCacheLoaderFactory - Specifies a BootstrapCacheLoader, which is called by a |
| cache on initialisation to prepopulate itself. |
| |
| * cacheExtensionFactory - Specifies a CacheExtension, a generic mechanism to tie a class |
| which holds a reference to a cache to the cache lifecycle. |
| |
| * cacheExceptionHandlerFactory - Specifies a CacheExceptionHandler, which is called when |
| cache exceptions occur. |
| |
| * cacheLoaderFactory - Specifies a CacheLoader, which can be used both asynchronously and |
| synchronously to load objects into a cache. More than one cacheLoaderFactory element |
| can be added, in which case the loaders form a chain which are executed in order. If a |
| loader returns null, the next in chain is called. |
| |
| * copyStrategy - Specifies a fully qualified class which implements |
| net.sf.ehcache.store.compound.CopyStrategy. This strategy will be used for copyOnRead |
| and copyOnWrite in place of the default which is serialization. |
| |
| Example of cache level resource tuning: |
| <cache name="memBound" maxBytesLocalHeap="100m" maxBytesLocalOffHeap="4g" maxBytesLocalDisk="200g" /> |
| |
| |
| Cache Event Listeners |
| +++++++++++++++++++++ |
| |
| All cacheEventListenerFactory elements can take an optional property listenFor that describes |
| which events will be delivered in a clustered environment. The listenFor attribute has the |
| following allowed values: |
| |
| * all - the default is to deliver all local and remote events |
| * local - deliver only events originating in the current node |
| * remote - deliver only events originating in other nodes |
| |
| Example of setting up a logging listener for local cache events: |
| |
| <cacheEventListenerFactory class="my.company.log.CacheLogger" |
| listenFor="local" /> |
| |
| |
| Search |
| ++++++ |
| |
| A <cache> can be made searchable by adding a <searchable/> sub-element. By default the keys |
| and value objects of elements put into the cache will be attributes against which |
| queries can be expressed. |
| |
| <cache> |
| <searchable/> |
| </cache> |
| |
| |
| An "attribute" of the cache elements can also be defined to be searchable. In the example below |
| an attribute with the name "age" will be available for use in queries. The value for the "age" |
| attribute will be computed by calling the method "getAge()" on the value object of each element |
| in the cache. See net.sf.ehcache.search.attribute.ReflectionAttributeExtractor for the format of |
| attribute expressions. Attribute values must also conform to the set of types documented in the |
| net.sf.ehcache.search.attribute.AttributeExtractor interface |
| |
| <cache> |
| <searchable> |
| <searchAttribute name="age" expression="value.getAge()"/> |
| </searchable> |
| </cache> |
| |
| |
| Attributes may also be defined using a JavaBean style. With the following attribute declaration |
| a public method getAge() will be expected to be found on either the key or value for cache elements |
| |
| <cache> |
| <searchable> |
| <searchAttribute name="age"/> |
| </searchable> |
| </cache> |
| |
| In more complex situations you can create your own attribute extractor by implementing the |
| AttributeExtractor interface. Providing your extractor class is shown in the following example: |
| |
| <cache> |
| <searchable> |
| <searchAttribute name="age" class="com.example.MyAttributeExtractor"/> |
| </searchable> |
| </cache> |
| |
| Use properties to pass state to your attribute extractor if needed. Your implementation must provide |
| a public constructor that takes a single java.util.Properties instance |
| |
| <cache> |
| <searchable> |
| <searchAttribute name="age" class="com.example.MyAttributeExtractor" properties="foo=1,bar=2"/> |
| </searchable> |
| </cache> |
| |
| |
| RMI Cache Replication |
| +++++++++++++++++++++ |
| |
| Each cache that will be distributed needs to set a cache event listener which replicates |
| messages to the other CacheManager peers. For the built-in RMI implementation this is done |
| by adding a cacheEventListenerFactory element of type RMICacheReplicatorFactory to each |
| distributed cache's configuration as per the following example: |
| |
| <cacheEventListenerFactory class="net.sf.ehcache.distribution.RMICacheReplicatorFactory" |
| properties="replicateAsynchronously=true, |
| replicatePuts=true, |
| replicatePutsViaCopy=false, |
| replicateUpdates=true, |
| replicateUpdatesViaCopy=true, |
| replicateRemovals=true, |
| asynchronousReplicationIntervalMillis=<number of milliseconds>, |
| asynchronousReplicationMaximumBatchSize=<number of operations>" |
| propertySeparator="," /> |
| |
| The RMICacheReplicatorFactory recognises the following properties: |
| |
| * replicatePuts=true|false - whether new elements placed in a cache are |
| replicated to others. Defaults to true. |
| |
| * replicatePutsViaCopy=true|false - whether the new elements are |
| copied to other caches (true), or whether a remove message is sent. Defaults to true. |
| |
| * replicateUpdates=true|false - whether new elements which override an |
| element already existing with the same key are replicated. Defaults to true. |
| |
| * replicateRemovals=true - whether element removals are replicated. Defaults to true. |
| |
| * replicateAsynchronously=true | false - whether replications are |
| asynchronous (true) or synchronous (false). Defaults to true. |
| |
| * replicateUpdatesViaCopy=true | false - whether the new elements are |
| copied to other caches (true), or whether a remove message is sent. Defaults to true. |
| |
| * asynchronousReplicationIntervalMillis=<number of milliseconds> - The asynchronous |
| replicator runs at a set interval of milliseconds. The default is 1000. The minimum |
| is 10. This property is only applicable if replicateAsynchronously=true |
| |
| * asynchronousReplicationMaximumBatchSize=<number of operations> - The maximum |
| number of operations that will be batch within a single RMI message. The default |
| is 1000. This property is only applicable if replicateAsynchronously=true |
| |
| JGroups Replication |
| +++++++++++++++++++ |
| |
| For the Jgroups replication this is done with: |
| <cacheEventListenerFactory class="net.sf.ehcache.distribution.jgroups.JGroupsCacheReplicatorFactory" |
| properties="replicateAsynchronously=true, replicatePuts=true, |
| replicateUpdates=true, replicateUpdatesViaCopy=false, |
| replicateRemovals=true,asynchronousReplicationIntervalMillis=1000"/> |
| This listener supports the same properties as the RMICacheReplicationFactory. |
| |
| |
| JMS Replication |
| +++++++++++++++ |
| |
| For JMS-based replication this is done with: |
| <cacheEventListenerFactory |
| class="net.sf.ehcache.distribution.jms.JMSCacheReplicatorFactory" |
| properties="replicateAsynchronously=true, |
| replicatePuts=true, |
| replicateUpdates=true, |
| replicateUpdatesViaCopy=true, |
| replicateRemovals=true, |
| asynchronousReplicationIntervalMillis=1000" |
| propertySeparator=","/> |
| |
| This listener supports the same properties as the RMICacheReplicationFactory. |
| |
| Cluster Bootstrapping |
| +++++++++++++++++++++ |
| |
| Bootstrapping a cluster may use a different mechanism to replication. e.g you can mix |
| JMS replication with bootstrap via RMI - just make sure you have the cacheManagerPeerProviderFactory |
| and cacheManagerPeerListenerFactory configured. |
| |
| There are two bootstrapping mechanisms: RMI and JGroups. |
| |
| RMI Bootstrap |
| |
| The RMIBootstrapCacheLoader bootstraps caches in clusters where RMICacheReplicators are |
| used. It is configured as per the following example: |
| |
| <bootstrapCacheLoaderFactory |
| class="net.sf.ehcache.distribution.RMIBootstrapCacheLoaderFactory" |
| properties="bootstrapAsynchronously=true, maximumChunkSizeBytes=5000000" |
| propertySeparator="," /> |
| |
| The RMIBootstrapCacheLoaderFactory recognises the following optional properties: |
| |
| * bootstrapAsynchronously=true|false - whether the bootstrap happens in the background |
| after the cache has started. If false, bootstrapping must complete before the cache is |
| made available. The default value is true. |
| |
| * maximumChunkSizeBytes=<integer> - Caches can potentially be very large, larger than the |
| memory limits of the VM. This property allows the bootstraper to fetched elements in |
| chunks. The default chunk size is 5000000 (5MB). |
| |
| JGroups Bootstrap |
| |
| Here is an example of bootstrap configuration using JGroups boostrap: |
| |
| <bootstrapCacheLoaderFactory class="net.sf.ehcache.distribution.jgroups.JGroupsBootstrapCacheLoaderFactory" |
| properties="bootstrapAsynchronously=true"/> |
| |
| The configuration properties are the same as for RMI above. Note that JGroups bootstrap only supports |
| asynchronous bootstrap mode. |
| |
| |
| Cache Exception Handling |
| ++++++++++++++++++++++++ |
| |
| By default, most cache operations will propagate a runtime CacheException on failure. An |
| interceptor, using a dynamic proxy, may be configured so that a CacheExceptionHandler can |
| be configured to intercept Exceptions. Errors are not intercepted. |
| |
| It is configured as per the following example: |
| |
| <cacheExceptionHandlerFactory class="com.example.ExampleExceptionHandlerFactory" |
| properties="logLevel=FINE"/> |
| |
| Caches with ExceptionHandling configured are not of type Cache, but are of type Ehcache only, |
| and are not available using CacheManager.getCache(), but using CacheManager.getEhcache(). |
| |
| |
| Cache Loader |
| ++++++++++++ |
| |
| A default CacheLoader may be set which loads objects into the cache through asynchronous and |
| synchronous methods on Cache. This is different to the bootstrap cache loader, which is used |
| only in distributed caching. |
| |
| It is configured as per the following example: |
| |
| <cacheLoaderFactory class="com.example.ExampleCacheLoaderFactory" |
| properties="type=int,startCounter=10"/> |
| |
| Element value comparator |
| ++++++++++++++++++++++++ |
| |
| These two cache atomic methods: |
| removeElement(Element e) |
| replace(Element old, Element element) |
| |
| rely on comparison of cached elements value. The default implementation relies on Object.equals() |
| but that can be changed in case you want to use a different way to compute equality of two elements. |
| |
| This is configured as per the following example: |
| |
| <elementValueComparator class="com.company.xyz.MyElementComparator"/> |
| |
| The MyElementComparator class must implement the is net.sf.ehcache.store.ElementValueComparator |
| interface. The default implementation is net.sf.ehcache.store.DefaultElementValueComparator. |
| |
| |
| SizeOf Policy |
| +++++++++++++ |
| |
| Control how deep the SizeOf engine can go when sizing on-heap elements. |
| |
| This is configured as per the following example: |
| |
| <sizeOfPolicy maxDepth="100" maxDepthExceededBehavior="abort"/> |
| |
| maxDepth controls how many linked objects can be visited before the SizeOf engine takes any action. |
| maxDepthExceededBehavior specifies what happens when the max depth is exceeded while sizing an object graph. |
| "continue" makes the SizeOf engine log a warning and continue the sizing. This is the default. |
| "abort" makes the SizeOf engine abort the sizing, log a warning and mark the cache as not correctly tracking |
| memory usage. This makes Ehcache.hasAbortedSizeOf() return true when this happens. |
| |
| The SizeOf policy can be configured at the cache manager level (directly under <ehcache>) and at |
| the cache level (under <cache> or <defaultCache>). The cache policy always overrides the cache manager |
| one if both are set. This element has no effect on distributed caches. |
| |
| Transactions |
| ++++++++++++ |
| |
| To enable an ehcache as transactions, set the transactionalMode |
| |
| transactionalMode="xa" - high performance JTA/XA implementation |
| transactionalMode="xa_strict" - canonically correct JTA/XA implementation |
| transactionMode="local" - high performance local transactions involving caches only |
| transactionalMode="off" - the default, no transactions |
| |
| If set, all cache operations will need to be done through transactions. |
| |
| To prevent users keeping references on stored elements and modifying them outside of any transaction's control, |
| transactions also require the cache to be configured copyOnRead and copyOnWrite. |
| |
| CacheWriter |
| ++++++++++++ |
| |
| A CacheWriter can be set to write to an underlying resource. Only one CacheWriter can be |
| configured per cache. |
| |
| The following is an example of how to configure CacheWriter for write-through: |
| |
| <cacheWriter writeMode="write-through" notifyListenersOnException="true"> |
| <cacheWriterFactory class="net.sf.ehcache.writer.TestCacheWriterFactory" |
| properties="type=int,startCounter=10"/> |
| </cacheWriter> |
| |
| The following is an example of how to configure CacheWriter for write-behind: |
| |
| <cacheWriter writeMode="write-behind" minWriteDelay="1" maxWriteDelay="5" |
| rateLimitPerSecond="5" writeCoalescing="true" writeBatching="true" writeBatchSize="1" |
| retryAttempts="2" retryAttemptDelaySeconds="1"> |
| <cacheWriterFactory class="net.sf.ehcache.writer.TestCacheWriterFactory" |
| properties="type=int,startCounter=10"/> |
| </cacheWriter> |
| |
| The cacheWriter element has the following attributes: |
| * writeMode: the write mode, write-through or write-behind |
| |
| These attributes only apply to write-through mode: |
| * notifyListenersOnException: Sets whether to notify listeners when an exception occurs on a writer operation. |
| |
| These attributes only apply to write-behind mode: |
| * minWriteDelay: Set the minimum number of seconds to wait before writing behind. If set to a value greater than 0, |
| it permits operations to build up in the queue. This is different from the maximum write delay in that by waiting |
| a minimum amount of time, work is always being built up. If the minimum write delay is set to zero and the |
| CacheWriter performs its work very quickly, the overhead of processing the write behind queue items becomes very |
| noticeable in a cluster since all the operations might be done for individual items instead of for a collection |
| of them. |
| * maxWriteDelay: Set the maximum number of seconds to wait before writing behind. If set to a value greater than 0, |
| it permits operations to build up in the queue to enable effective coalescing and batching optimisations. |
| * writeBatching: Sets whether to batch write operations. If set to true, writeAll and deleteAll will be called on |
| the CacheWriter rather than write and delete being called for each key. Resources such as databases can perform |
| more efficiently if updates are batched, thus reducing load. |
| * writeBatchSize: Sets the number of operations to include in each batch when writeBatching is enabled. If there are |
| less entries in the write-behind queue than the batch size, the queue length size is used. |
| * rateLimitPerSecond: Sets the maximum number of write operations to allow per second when writeBatching is enabled. |
| * writeCoalescing: Sets whether to use write coalescing. If set to true and multiple operations on the same key are |
| present in the write-behind queue, only the latest write is done, as the others are redundant. |
| * retryAttempts: Sets the number of times the operation is retried in the CacheWriter, this happens after the |
| original operation. |
| * retryAttemptDelaySeconds: Sets the number of seconds to wait before retrying an failed operation. |
| |
| Cache Extension |
| +++++++++++++++ |
| |
| CacheExtensions are a general purpose mechanism to allow generic extensions to a Cache. |
| CacheExtensions are tied into the Cache lifecycle. |
| |
| CacheExtensions are created using the CacheExtensionFactory which has a |
| <code>createCacheCacheExtension()</code> method which takes as a parameter a |
| Cache and properties. It can thus call back into any public method on Cache, including, of |
| course, the load methods. |
| |
| Extensions are added as per the following example: |
| |
| <cacheExtensionFactory class="com.example.FileWatchingCacheRefresherExtensionFactory" |
| properties="refreshIntervalMillis=18000, loaderTimeout=3000, |
| flushPeriod=whatever, someOtherProperty=someValue ..."/> |
| |
| Cache Decorator Factory |
| +++++++++++++++++++++++ |
| |
| Cache decorators can be configured directly in ehcache.xml. The decorators will be created and added to the CacheManager. |
| It accepts the name of a concrete class that extends net.sf.ehcache.constructs.CacheDecoratorFactory |
| The properties will be parsed according to the delimiter (default is comma ',') and passed to the concrete factory's |
| <code>createDecoratedEhcache(Ehcache cache, Properties properties)</code> method along with the reference to the owning cache. |
| |
| It is configured as per the following example: |
| |
| <cacheDecoratorFactory |
| class="com.company.DecoratedCacheFactory" |
| properties="property1=true ..." /> |
| |
| Distributed Caching with Terracotta |
| +++++++++++++++++++++++++++++++++++ |
| |
| Distributed Caches connect to a Terracotta Server Array. They are configured with the <terracotta> sub-element. |
| |
| The <terracotta> sub-element has the following attributes: |
| |
| * clustered=true|false - indicates whether this cache should be clustered (distributed) with Terracotta. By |
| default, if the <terracotta> element is included, clustered=true. |
| |
| * valueMode=serialization|identity - the default is serialization |
| |
| Indicates whether cache Elements are distributed with serialized copies or whether a single copy |
| in identity mode is distributed. |
| |
| The implications of Identity mode should be clearly understood with reference to the Terracotta |
| documentation before use. |
| |
| * copyOnRead=true|false - indicates whether cache values are deserialized on every read or if the |
| materialized cache value can be re-used between get() calls. This setting is useful if a cache |
| is being shared by callers with disparate classloaders or to prevent local drift if keys/values |
| are mutated locally without being put back in the cache. |
| |
| The default is false. |
| |
| Note: This setting is only relevant for caches with valueMode=serialization |
| |
| * consistency=strong|eventual - Indicates whether this cache should have strong consistency or eventual |
| consistency. The default is eventual. See the documentation for the meaning of these terms. |
| |
| * synchronousWrites=true|false |
| |
| Synchronous writes (synchronousWrites="true") maximize data safety by blocking the client thread until |
| the write has been written to the Terracotta Server Array. |
| |
| This option is only available with consistency=strong. The default is false. |
| |
| * concurrency - the number of segments that will be used by the map underneath the Terracotta Store. |
| Its optional and has default value of 0, which means will use default values based on the internal |
| Map being used underneath the store. |
| |
| This value cannot be changed programmatically once a cache is initialized. |
| |
| The <terracotta> sub-element also has a <nonstop> sub-element to allow configuration of cache behaviour if a distributed |
| cache operation cannot be completed within a set time or in the event of a clusterOffline message. If this element does not appear, nonstop behavior is off. |
| |
| <nonstop> has the following attributes: |
| |
| * enabled="true" - defaults to true. |
| |
| * timeoutMillis - An SLA setting, so that if a cache operation takes longer than the allowed ms, it will timeout. |
| |
| * immediateTimeout="true|false" - What to do on receipt of a ClusterOffline event indicating that communications |
| with the Terracotta Server Array were interrupted. |
| |
| <nonstop> has one sub-element, <timeoutBehavior> which has the following attribute: |
| |
| * type="noop|exception|localReads" - What to do when a timeout has occurred. Exception is the default. |
| |
| Simplest example to indicate clustering: |
| <terracotta/> |
| |
| To indicate the cache should not be clustered (or remove the <terracotta> element altogether): |
| <terracotta clustered="false"/> |
| |
| To indicate the cache should be clustered using identity mode: |
| <terracotta clustered="true" valueMode="identity"/> |
| |
| To indicate the cache should be clustered using "eventual" consistency mode for better performance : |
| <terracotta clustered="true" consistency="eventual"/> |
| |
| To indicate the cache should be clustered using synchronous-write locking level: |
| <terracotta clustered="true" synchronousWrites="true"/> |
| --> |
| |
| <!-- |
| Default Cache configuration. These settings will be applied to caches |
| created programmatically using CacheManager.add(String cacheName). |
| This element is optional, and using CacheManager.add(String cacheName) when |
| its not present will throw CacheException |
| |
| The defaultCache has an implicit name "default" which is a reserved cache name. |
| --> |
| <defaultCache |
| maxEntriesLocalHeap="10000" |
| eternal="false" |
| timeToIdleSeconds="120" |
| timeToLiveSeconds="120" |
| diskSpoolBufferSizeMB="30" |
| maxEntriesLocalDisk="10000000" |
| diskExpiryThreadIntervalSeconds="120" |
| memoryStoreEvictionPolicy="LRU" |
| statistics="false"> |
| <persistence strategy="localTempSwap"/> |
| </defaultCache> |
| |
| <!-- |
| Sample caches. Following are some example caches. Remove these before use. |
| --> |
| |
| <cache name="ldcache" |
| maxEntriesLocalHeap="10000" |
| maxEntriesLocalDisk="1000" |
| eternal="false" |
| diskSpoolBufferSizeMB="20" |
| timeToIdleSeconds="300" |
| timeToLiveSeconds="600" |
| memoryStoreEvictionPolicy="LFU" |
| transactionalMode="off"> |
| <persistence strategy="localTempSwap"/> |
| </cache> |
| |
| |
| |
| </ehcache> |
