Persist and Replay Runtime Data Using Apache Java Caching

System and Javassist

https://bitbucket.org/wishcoder/jcs.marketdata.replay/wiki/Home

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Persist and Replay Runtime Data

• The ability to persist data created at runtime is useful when application states and data are required to be replayed multiple times to investigate application issues.

• This article demonstrates how to persist

runtime data to disk and load disk persisted data to replay in new JVM instances.

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Apache JCS and Javassist

• JCS is a distributed caching system written in Java. Indexed Disk Auxiliary Cache is used to persist data on disk. JCS only persist Serializable java objects.

• Javassist (Java Programming Assistant) makes Java bytecode manipulation simple. Javassist is used to dynamically set values for transient fields that are not persisted due to transient nature.

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Maven Dependencies<properties>

<org.javassist-version>3.19.0-GA</org.javassist-version><jcs-version>1.3</jcs-version>

</properties>

<dependencies><dependency><groupId>org.javassist</groupId><artifactId>javassist</artifactId><version>${org.javassist-version}</version></dependency><dependency><groupId>jcs</groupId><artifactId>jcs</artifactId><version>${jcs-version}</version></dependency>

</dependencies>

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Log4j Settings for JCS<appender name="CONSOLE" class="org.apache.log4j.ConsoleAppender">

<layout class="org.apache.log4j.PatternLayout"><param name="ConversionPattern" value="%d [%t] %C{1} %p - %m%n"/>

</layout></appender>

<logger name="org.apache.jcs"><!– DEBUG level in dev mode will enable useful logs from JCS jar -><!– DON’T PUT THIS IN PRODUCTION ENVIRONMENT -><level value="DEBUG"/><appender-ref ref="CONSOLE"/>

</logger>

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Setup JCS - DEFAULT CACHE REGION

Properties props = new Properties();

props.put("jcs.default", "DC");props.put("jcs.default.cacheattributes", "org.apache.jcs.engine.CompositeCacheAttributes");props.put("jcs.default.cacheattributes.MaxObjects", 1000);props.put("jcs.default.cacheattributes.MemoryCacheName", "org.apache.jcs.engine.memory.lru.LRUMemoryCache");props.put("jcs.default.cacheattributes.DiskUsagePatternName", "UPDATE");props.put("jcs.default.elementattributes", "org.apache.jcs.engine.ElementAttributes");props.put("jcs.default.elementattributes.IsSpool", "true");props.put("jcs.region.elementattributes.IsEternal", "false");props.put("jcs.default.elementattributes.IsLateral", "false");props.put("jcs.default.elementattributes.IsRemote", "false");

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Setup JCS - AUXILARY/DISK CACHEprops.put("jcs.auxiliary.DC", "org.apache.jcs.auxiliary.disk.indexed.IndexedDiskCacheFactory");props.put("jcs.auxiliary.DC.attributes", "org.apache.jcs.auxiliary.disk.indexed.IndexedDiskCacheAttributes");props.put("jcs.auxiliary.DC.attributes.DiskPath", “C:\TradeCache”);props.put("jcs.auxiliary.DC.attributes.MaxPurgatorySize", "10000000"); // 10000000// If the maximum key size is less than 0, no limit will be placed on// the number of keys. By default, the max key size is 5000.props.put("jcs.auxiliary.DC.attributes.MaxKeySize", "-1");

// Use Thread Pool for disk operationprops.put("jcs.auxiliary.DC.attributes.EventQueueType", "POOLED");props.put("jcs.auxiliary.DC.attributes.EventQueuePoolName", "disk_cache_event_queue");

// Disk Cache Event Queue Poolprops.put("thread_pool.disk_cache_event_queue.useBoundary", "false");props.put("thread_pool.remote_cache_client.maximumPoolSize", "15");props.put("thread_pool.disk_cache_event_queue.minimumPoolSize", "1");props.put("thread_pool.disk_cache_event_queue.keepAliveTime", "3500");props.put("thread_pool.disk_cache_event_queue.startUpSize", "1");

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Setup JCS – CUSTOM DATA CACHE REGION

props.put("jcs.region.marketdata_cache", "DC");props.put("jcs.region.marketdata_cache.cacheattributes", "org.apache.jcs.engine.CompositeCacheAttributes");props.put("jcs.region.marketdata_cache.cacheattributes.MaxObjects", maxObjectInMemory);props.put("jcs.region.marketdata_cache.cacheattributes.MemoryCacheName",

"org.apache.jcs.engine.memory.lru.LRUMemoryCache");props.put("jcs.region.marketdata_cache.cacheattributes.DiskUsagePatternName", "UPDATE");props.put("jcs.region.marketdata_cache.elementattributes", "org.apache.jcs.engine.ElementAttributes");props.put("jcs.region.marketdata_cache.elementattributes.IsEternal", "false");props.put("jcs.region.marketdata_cache.elementattributes.IsLateral", "false");props.put("jcs.region.marketdata_cache.elementattributes.IsRemote", "false");

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Initialize and use JCSCompositeCacheManager ccm = CompositeCacheManager.getUnconfiguredInstance();ccm.configure(props )

CacheAccess cCache = JCS.getInstance(“marketdata_cache”);

• Write cCache.put(Object name, Object obj);

• ReadObject obj = cCache.get(name);

• Persist Cache To Disk // marketdata_cache.data and marketdata_cache.key files generatedcCache.dispose();

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JCS - Load Data From CacheCompositeCacheManager ccm = CompositeCacheManager.getUnconfiguredInstance();ccm.configure(props )

CacheAccess cCache = JCS.getInstance(“marketdata_cache”);

• ReadObject obj = cCache.get(name);

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Javassist – Inject Transient Data

Javassist (Java Programming Assistant) makes Java bytecode manipulation simple. Javassist is used to dynamically set values for transient fields that are not persisted due to transient nature.

Ajay Singh | message4ajay@gmail.com | LinkedIn - https://www.linkedin.com/in/ajaysinghonline | Bitbucket - https://bitbucket.org/wishcoder

Javassist – Helper Class CacheReplayHelper .javahttps://bitbucket.org/wishcoder/jcs.marketdata.replay/raw/de77eb8afaa818d21b1ac4bd1f0c90bc99521cd4/jcs.marketdata.replay/trade.common/src/main/java/com/wishcoder/samples/jcs/trade/common/cache/CacheReplayHelper.java

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Javassist – Dynamically Add Setter Method

List<CtMethod> setterMethods = new ArrayList<CtMethod>();CtClass sourceClass =

ClassPool.getDefault().get("com.wishcoder.samples.jcs.trade.common.data.TickEvent");CtMethod setSourceMethod = getCacheManager().getMethod(sourceClass,

"setSource", "source","com.wishcoder.samples.jcs.trade.common.data.User");

setterMethods.add(setTickBookMethod);CacheReplayHelper.addSetterMethods(sourceClass, setterMethods);

Class<?>[] userObject = new Class[1];userObject[0] =

Class.forName("com.wishcoder.samples.jcs.trade.common.data.User");HashMap<String, Class<?>[]> parameterMap = new HashMap<String, Class<?>[]>();parameterMap.put("setSource", userObject);

CacheReplayHelper.prepareNonSerializeSetters("com.wishcoder.samples.jcs.trade.common.data.TickEvent",parameterMap);

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Javassist – Set Transient Data • Read object from JCS Cache:CompositeCacheManager ccm = CompositeCacheManager.getUnconfiguredInstance();ccm.configure(props )

CacheAccess cCache = JCS.getInstance(“marketdata_cache”);Object cachedObject = cCache.get(name);

• Initialize object that need to be injected in cached objectUser user = new User(‘1’, ‘Name’);

• Inject Transient data in cached object cachedObject = CacheReplayHelper.setNonSerializeSetter(cachedObject ,"setSource", user );

Ajay Singh | message4ajay@gmail.com | LinkedIn - https://www.linkedin.com/in/ajaysinghonline | Bitbucket - https://bitbucket.org/wishcoder

Wiki and Source Repository

https://bitbucket.org/wishcoder/jcs.marketdata.replay/wiki/Home

Ajay Singh | message4ajay@gmail.com | LinkedIn - https://www.linkedin.com/in/ajaysinghonline | Bitbucket - https://bitbucket.org/wishcoder

Useful Links

• Log4J• Java• Java MigLayout• Javassist• Apache Java Caching System - JCS

Ajay Singh | message4ajay@gmail.com | LinkedIn - https://www.linkedin.com/in/ajaysinghonline | Bitbucket - https://bitbucket.org/wishcoder

Questions?

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Bitbucket - https://bitbucket.org/wishcoder Slideshare - http://www.slideshare.net/ajaysingh672

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