Caffeine Cache

Since Camel 2.20

Only producer is supported

The Caffeine Cache component enables you to perform caching operations using the simple cache from Caffeine.

Maven users will need to add the following dependency to their pom.xml for this component:

<dependency>
    <groupId>org.apache.camel</groupId>
    <artifactId>camel-caffeine</artifactId>
    <version>x.x.x</version>
    <!-- use the same version as your Camel core version -->
</dependency>
caffeine-cache://cacheName[?options]

You can append query options to the URI in the following format, ?option=value&option=#beanRef&…​

Configuring Options

Camel components are configured on two separate levels:

  • component level

  • endpoint level

Configuring Component Options

The component level is the highest level which holds general and common configurations that are inherited by the endpoints. For example a component may have security settings, credentials for authentication, urls for network connection and so forth.

Some components only have a few options, and others may have many. Because components typically have pre configured defaults that are commonly used, then you may often only need to configure a few options on a component; or none at all.

Configuring components can be done with the Component DSL, in a configuration file (application.properties|yaml), or directly with Java code.

Configuring Endpoint Options

Where you find yourself configuring the most is on endpoints, as endpoints often have many options, which allows you to configure what you need the endpoint to do. The options are also categorized into whether the endpoint is used as consumer (from) or as a producer (to), or used for both.

Configuring endpoints is most often done directly in the endpoint URI as path and query parameters. You can also use the Endpoint DSL and DataFormat DSL as a type safe way of configuring endpoints and data formats in Java.

A good practice when configuring options is to use Property Placeholders, which allows to not hardcode urls, port numbers, sensitive information, and other settings. In other words placeholders allows to externalize the configuration from your code, and gives more flexibility and reuse.

The following two sections lists all the options, firstly for the component followed by the endpoint.

Component Options

The Caffeine Cache component supports 16 options, which are listed below.

Name Description Default Type

action (producer)

To configure the default cache action. If an action is set in the message header, then the operation from the header takes precedence.

Enum values:

  • GET

  • GET_ALL

  • PUT

  • PUT_ALL

  • INVALIDATE

  • INVALIDATE_ALL

  • CLEANUP

  • AS_MAP

String

createCacheIfNotExist (producer)

Automatic create the Caffeine cache if none has been configured or exists in the registry.

true

boolean

evictionType (producer)

Set the eviction Type for this cache.

Enum values:

  • size_based

  • time_based

SIZE_BASED

EvictionType

expireAfterAccessTime (producer)

Specifies that each entry should be automatically removed from the cache once a fixed duration has elapsed after the entry’s creation, the most recent replacement of its value, or its last read. Access time is reset by all cache read and write operations. The unit is in seconds.

300

int

expireAfterWriteTime (producer)

Specifies that each entry should be automatically removed from the cache once a fixed duration has elapsed after the entry’s creation, or the most recent replacement of its value. The unit is in seconds.

300

int

initialCapacity (producer)

Sets the minimum total size for the internal data structures. Providing a large enough estimate at construction time avoids the need for expensive resizing operations later, but setting this value unnecessarily high wastes memory.

Integer

key (producer)

To configure the default action key. If a key is set in the message header, then the key from the header takes precedence.

String

lazyStartProducer (producer)

Whether the producer should be started lazy (on the first message). By starting lazy you can use this to allow CamelContext and routes to startup in situations where a producer may otherwise fail during starting and cause the route to fail being started. By deferring this startup to be lazy then the startup failure can be handled during routing messages via Camel’s routing error handlers. Beware that when the first message is processed then creating and starting the producer may take a little time and prolong the total processing time of the processing.

false

boolean

maximumSize (producer)

Specifies the maximum number of entries the cache may contain. Note that the cache may evict an entry before this limit is exceeded or temporarily exceed the threshold while evicting. As the cache size grows close to the maximum, the cache evicts entries that are less likely to be used again. For example, the cache may evict an entry because it hasn’t been used recently or very often. When size is zero, elements will be evicted immediately after being loaded into the cache. This can be useful in testing, or to disable caching temporarily without a code change. As eviction is scheduled on the configured executor, tests may instead prefer to configure the cache to execute tasks directly on the same thread.

Integer

autowiredEnabled (advanced)

Whether autowiring is enabled. This is used for automatic autowiring options (the option must be marked as autowired) by looking up in the registry to find if there is a single instance of matching type, which then gets configured on the component. This can be used for automatic configuring JDBC data sources, JMS connection factories, AWS Clients, etc.

true

boolean

cacheLoader (advanced)

To configure a CacheLoader in case of a LoadCache use.

CacheLoader

configuration (advanced)

Sets the global component configuration.

CaffeineConfiguration

removalListener (advanced)

Set a specific removal Listener for the cache.

RemovalListener

statsCounter (advanced)

Set a specific Stats Counter for the cache stats.

StatsCounter

statsEnabled (advanced)

To enable stats on the cache.

false

boolean

valueType (advanced)

The cache value type, default java.lang.Object.

String

Endpoint Options

The Caffeine Cache endpoint is configured using URI syntax:

caffeine-cache:cacheName

with the following path and query parameters:

Path Parameters (1 parameters)

Name Description Default Type

cacheName (producer)

Required Cache name.

String

Query Parameters (14 parameters)

Name Description Default Type

action (producer)

To configure the default cache action. If an action is set in the message header, then the operation from the header takes precedence.

Enum values:

  • GET

  • GET_ALL

  • PUT

  • PUT_ALL

  • INVALIDATE

  • INVALIDATE_ALL

  • CLEANUP

  • AS_MAP

String

createCacheIfNotExist (producer)

Automatic create the Caffeine cache if none has been configured or exists in the registry.

true

boolean

evictionType (producer)

Set the eviction Type for this cache.

Enum values:

  • size_based

  • time_based

SIZE_BASED

EvictionType

expireAfterAccessTime (producer)

Specifies that each entry should be automatically removed from the cache once a fixed duration has elapsed after the entry’s creation, the most recent replacement of its value, or its last read. Access time is reset by all cache read and write operations. The unit is in seconds.

300

int

expireAfterWriteTime (producer)

Specifies that each entry should be automatically removed from the cache once a fixed duration has elapsed after the entry’s creation, or the most recent replacement of its value. The unit is in seconds.

300

int

initialCapacity (producer)

Sets the minimum total size for the internal data structures. Providing a large enough estimate at construction time avoids the need for expensive resizing operations later, but setting this value unnecessarily high wastes memory.

Integer

key (producer)

To configure the default action key. If a key is set in the message header, then the key from the header takes precedence.

String

maximumSize (producer)

Specifies the maximum number of entries the cache may contain. Note that the cache may evict an entry before this limit is exceeded or temporarily exceed the threshold while evicting. As the cache size grows close to the maximum, the cache evicts entries that are less likely to be used again. For example, the cache may evict an entry because it hasn’t been used recently or very often. When size is zero, elements will be evicted immediately after being loaded into the cache. This can be useful in testing, or to disable caching temporarily without a code change. As eviction is scheduled on the configured executor, tests may instead prefer to configure the cache to execute tasks directly on the same thread.

Integer

lazyStartProducer (producer (advanced))

Whether the producer should be started lazy (on the first message). By starting lazy you can use this to allow CamelContext and routes to startup in situations where a producer may otherwise fail during starting and cause the route to fail being started. By deferring this startup to be lazy then the startup failure can be handled during routing messages via Camel’s routing error handlers. Beware that when the first message is processed then creating and starting the producer may take a little time and prolong the total processing time of the processing.

false

boolean

cacheLoader (advanced)

To configure a CacheLoader in case of a LoadCache use.

CacheLoader

removalListener (advanced)

Set a specific removal Listener for the cache.

RemovalListener

statsCounter (advanced)

Set a specific Stats Counter for the cache stats.

StatsCounter

statsEnabled (advanced)

To enable stats on the cache.

false

boolean

valueType (advanced)

The cache value type, default java.lang.Object.

String

Message Headers

The Caffeine Cache component supports 7 message header(s), which is/are listed below:

Name Description Default Type

CamelCaffeineAction (producer)

Constant: ACTION

The action to execute. Possible values: CLEANUP PUT PUT_ALL GET GET_ALL INVALIDATE INVALIDATE_ALL AS_MAP.

String

CamelCaffeineActionHasResult (producer)

Constant: ACTION_HAS_RESULT

The flag indicating whether the action has a result or not.

Boolean

CamelCaffeineActionSucceeded (producer)

Constant: ACTION_SUCCEEDED

The flag indicating whether the action was successful or not.

Boolean

CamelCaffeineKey (producer)

Constant: KEY

The key for all actions on a single entry.

CamelCaffeineKeys (producer)

Constant: KEYS

The keys to get (GET_ALL), to invalidate (INVALIDATE_ALL) or existing (AS_MAP) according to the action.

Set

CamelCaffeineValue (producer)

Constant: VALUE

The value of key for all put actions (PUT or PUT_ALL).

CamelCaffeineOldValue (producer)

Constant: OLD_VALUE

The old value returned according to the action.

Examples

You can use your cache with the following code:

@BindToRegistry("cache")
Cache cache = Caffeine.newBuilder().recordStats().build();

@Override
protected RouteBuilder createRouteBuilder() throws Exception {
    return new RouteBuilder() {
        public void configure() {
            from("direct://start")
                .to("caffeine-cache://cache?action=PUT&key=1")
                .to("caffeine-cache://cache?key=1&action=GET")
                .log("Test! ${body}")
                .to("mock:result");
        }
    };
}

In this way you’ll work always on the same cache in the registry.

Check operation result

Each time you’ll use an operation on the cache you’ll have two different headers to check for status:

CaffeineConstants.ACTION_HAS_RESULT
CaffeineConstants.ACTION_SUCCEEDED