Examples of com.sun.messaging.jmq.util.PHashMapMMF

com.sun.messaging.jmq.util.PHashMapMMF
PHashMapMMF is a persistent HashMap that is backed by a memory-mapped file. Due to the nature of memory-mapped file, PHashMapMMF implementation can provide partial entry udpate optimization which greatly improves PHashMap update performance. In a standard PHashMap, the key and value object is either serialized or externalized as a VRecord and it is written to the backing file when an entry is updated, i.e. even when only a single field in the value object is modified. Partial entry update optimization is implemented by providing a client data section as part of the record and additional APIs to update just the client data section of the record. So instead of rewriting the whole record, the user of this class can just update the client data portion of the record, e.g. value of the modified field for the value object. Note: to use partial entry update optimization, the user of the this class is responsible for processing the client data and update the value object when PHashMapMMF is loaded (see com.sun.messaging.jmq.jmsserver.persist.file.TidList for example usage). Each record has the following layout:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| record header |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| serialized key object |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| serialized value object |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|%CD| client data section (optional) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

            _logger.log(Level.INFO, _jbr.getString(_jbr.I_FILETXNLOG_INIT, fname));
        }
        _backFile = new File(_txlogdir, fname);


        if (_useMmappedFile) {
            _gxidMap = new PHashMapMMF(_backFile, _logsize, 1024, false, reset);
            ((PHashMapMMF)_gxidMap).intClientData(_clientDataSize);
        } else {
            _gxidMap = new PHashMap(_backFile, _logsize, 1024, false, reset);
        }
        try {

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            useMemoryMappedFile = config.getBooleanProperty(
                TidList.TXN_USE_MEMORY_MAPPED_FILE_PROP,
                TidList.DEFAULT_TXN_USE_MEMORY_MAPPED_FILE);


            if (useMemoryMappedFile) {
          tidMap = new PHashMapMMF(
                    backingFile, filesize.getBytes(), 1024, false, clear);
            } else {
                tidMap = new PHashMap(
                    backingFile, filesize.getBytes(), 1024, false, clear);
            }

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  try {
      // pass in safe=false; let caller decide when to sync
      // safe=false; reset=false
            if (config.getBooleanProperty(TidList.TXN_USE_MEMORY_MAPPED_FILE_PROP,
                TidList.DEFAULT_TXN_USE_MEMORY_MAPPED_FILE)) {
          tidMap = new PHashMapMMF(
                    backingFile, oldFile.length(), 1024, false, false);
            } else {
                tidMap = new PHashMap(
                    backingFile, oldFile.length(), 1024, false, false);
            }

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                    TXN_UPDATE_OPTIMIZATION_PROP,
                    DEFAULT_TXN_UPDATE_OPTIMIZATION);


            // safe = false; caller controls data synchronization
            if (useMemoryMappedFile) {
                tidMap = new PHashMapMMF(
                    backingFile, filesize.getBytes(), 1024, false, clear);
                if (updateOptimization) {
                    ((PHashMapMMF)tidMap).intClientData(CLIENT_DATA_SIZE);
                }
            } else {

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                    DEFAULT_TXN_UPDATE_OPTIMIZATION);


            // pass in safe=false; caller decide when to sync
            // safe=false; reset=false
            if (useMemoryMappedFile) {
          tidMap = new PHashMapMMF(
                    backingFile, oldFile.length(), 1024, false, false);
                if (updateOptimization) {
                    ((PHashMapMMF)tidMap).intClientData(CLIENT_DATA_SIZE);
                }
            } else {

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                if (updateOptimization) {
                    // To improve I/O performance, just persist the new
                    // state as client data and not the whole record
                    byte[] cd = generateClientData(id, txnInfo);
                    PHashMapMMF tidMapMMF = (PHashMapMMF)tidMap;
                    tidMapMMF.putClientData(id, cd);
                } else {
                    tidMap.put(id, txnInfo);
                }
            } else {
                sync = false;   // No need to sync

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            if (updateOptimization) {
                // To improve I/O performance, just persist the new
                // state as client data and not the whole record
                byte[] cd = generateClientData(id, txnInfo);
                PHashMapMMF tidMapMMF = (PHashMapMMF)tidMap;
                tidMapMMF.putClientData(id, cd);


            } else {
                tidMap.put(id, txnInfo);
            }

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Related Classes of com.sun.messaging.jmq.util.PHashMapMMF

com.sun.messaging.bridge.service.jms.tx.log.FileTxLogImpl

com.sun.messaging.jmq.io.MQObjectInputStream

com.sun.messaging.jmq.io.VRecordMap

com.sun.messaging.jmq.io.VRFileMap

com.sun.messaging.jmq.jmsserver.persist.file.TidList

com.sun.messaging.jmq.jmsserver.persist.file.TxnAckList

java.util.concurrent.ConcurrentHashMap

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