...
The strategy has the following options:
Option | Default | Description | |||
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| | Base directory where temporary files for spooled streams should be stored. | spoolThreshold | 128kb | Size in bytes when the stream should be spooled to disk instead of keeping in memory. Use a value of 0 or negative to disable it all together so streams is always kept in memory regardless of their sizeThis option supports naming patterns as documented below. |
| | If set, the temporary files are encrypted using the specified cipher transformation (i.e., a valid stream or 8-bit cipher name such as "RC4", "AES/CTR/NoPadding". An empty name "" is treated as null). | |||
bufferSize | 4096 | Size in bytes when the stream should be spooled to disk instead of the buffer used in the streamkeeping in memory. Use a value of 0 or negative to disable it all together so streams is always kept in memory regardless of their size. | |||
| | A percentage (1 to 99) of current used heap memory to use as threshold for spooling streams to disk. The upper bounds is based on heap committed (guaranteed memory the JVM can claim). This can be used to spool to disk when running low on memory. | |||
| | If | |||
| | Whether any or all | |||
| | Initial size if in-memory created stream buffers. | |||
| | Whether to remove the spool directory when stopping CamelContext. | |||
| | Whether utilization statistics is enabled. By enabling this you can see these statics for example with JMX. |
SpoolDirectory naming pattern
The following patterns is supported:
- #uuid# = a random UUID
- #camelId# = the CamelContext id (eg the name)
- #name# - same as #camelId#
- #counter# - an incrementing counter
- #bundleId# - the OSGi bundle id (only for OSGi environments)
- #symbolicName# - the OSGi symbolic name (only for OSGi environments)
- #version# - the OSGi bundle version (only for OSGi environments)
- ${env:key} - the environment variable with the key
- ${key} - the JVM system property with the key
A could of examples, to store in the java temp directory with a sub directory using the CamelContext name:
Code Block |
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context.getStreamCachingStrategy().setSpoolDirectory"${java.io.tmpdir}#name#/");
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To store in KARAF_HOME/tmp/bundleId directory
Code Block |
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context.getStreamCachingStrategy().setSpoolDirectory"${env:KARAF_HOME}/tmp/bundle#bundleId#");
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Using StreamCachingStrategy in Java
...
Using StreamCachingStrategy in XML
And in XML you do:
Code Block | ||||
---|---|---|---|---|
| ||||
<camelContext streamCache="true" xmlns="http://camel.apache.org/schema/blueprint">
<streamCaching id="myCacheConfig" bufferSize="16384" spoolDirectory="/tmp/cachedir" spoolThreshold="65536"/>
<route>
<from uri="direct:c"/>
<to uri="mock:c"/>
</route>
</camelContext>
|
You can also define a <bean> instead of using the <streamCaching> tag:
And in XML you do
Code Block | ||||
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| ||||
<!-- define a bean of type StreamCachingStrategy which CamelContext will automatic use -->
<bean id="streamStrategy" class="org.apache.camel.impl.DefaultStreamCachingStrategy">
<property name="spoolDirectory" value="/tmp/cachedir"/>
<property name="spoolThreshold" value="65536"/>
<property name="bufferSize" value="16384"/>
</bean>
<!-- remember to enable stream caching -->
<camelContext streamCaching="true" xmlns="http://camel.apache.org/schema/spring">
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Using spoolUsedHeapMemoryThreshold
By default stream caching will spool only big payloads (128kb or bigger) to disk. However you can also set the spoolUsedHeapMemoryThreshold option which is a percentage of used heap memory. This can be used to also spool to disk when running low on memory.
For example with:
Code Block |
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<streamCaching id="myCacheConfig" spoolDirectory="/tmp/cachedir" spoolUsedHeapMemoryThreshold="70"/> |
Then notice that as spoolThreshold is default enabled with 128kb, then we have both thresholds in use (spoolThreshold and spoolUsedHeapMemoryThreshold). And in this example then we only spool to disk if payload is > 128kb and that used heap memory is > 70%. The reason is that we have the option anySpoolRules
as default false
. That means both rules must be true
(eg AND).
If we want to spool to disk if either of the rules (eg OR), then we can do:
Code Block |
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<streamCaching id="myCacheConfig" spoolDirectory="/tmp/cachedir" spoolUsedHeapMemoryThreshold="70" anySpoolRules="true"/>
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If we only want to spool to disk if we run low on memory then we can set:
Code Block |
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<streamCaching id="myCacheConfig" spoolDirectory="/tmp/cachedir" spoolThreshold="-1" spoolUsedHeapMemoryThreshold="70"/>
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... then we do not use the spoolThreshold rule, and only the heap memory based is in use.
By default the upper limit of the used heap memory is based on the maximum heap size. Though you can also configure to use the committed heap size as the upper limit, this is done using the spoolUsedHeapMemoryThreshold
option as shown below:
Code Block |
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<streamCaching id="myCacheConfig" spoolDirectory="/tmp/cachedir" spoolUsedHeapMemoryThreshold="70" spoolUsedHeapMemoryLimit="Committed"/>
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Using custom SpoolRule implementations
You can implement your custom rules to determine if the stream should be spooled to disk. This can be done by implementing the interface org.apache.camel.spi.StreamCachingStrategy.SpoolRule
which has a single method:
Code Block |
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boolean shouldSpoolCache(long length);
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The length is the length of the stream.
To use the rule then add it to the StreamCachingStrategy
as shown below:
Code Block |
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SpoolRule mySpoolRule = ...
context.getStreamCachingStrategy().addSpoolRule(mySpoolRule);
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And from XML you need to define a <bean> with your custom rule
Code Block | ||||
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| ||||
<bean id="mySpoolRule" class="com.foo.MySpoolRule"/>
<streamCaching id="myCacheConfig" spoolDirectory="/tmp/cachedir" spoolRules="mySpoolRule"/>
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Using the spoolRules
attribute on <streamCaching>. if you have more rules, then separate them by comma.
Code Block | ||||
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<streamCaching id="myCacheConfig" spoolDirectory="/tmp/cachedir" spoolRules="mySpoolRule,myOtherSpoolRule"/>
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How it works?
In order to determine if a type requires caching, we leverage the type converter feature. Any type that requires stream caching can be converted into an org.apache.camel.StreamCache
instance.