Examples of com.sleepycat.je.DatabaseEntry

com.sleepycat.je.DatabaseEntry
Encodes database key and data items as a byte array.
Storage and retrieval for the {@link com.sleepycat.je.Database Database}and {@link com.sleepycat.je.Cursor Cursor} methods are based on key/datapairs. Both key and data items are represented by DatabaseEntry objects. Key and data byte arrays may refer to arrays of zero length up to arrays of essentially unlimited length.

The DatabaseEntry class provides simple access to an underlying object whose elements can be examined or changed. DatabaseEntry objects can be subclassed, providing a way to associate with it additional data or references to other structures.

Access to DatabaseEntry objects is not re-entrant. In particular, if multiple threads simultaneously access the same DatabaseEntry object using {@link com.sleepycat.je.Database Database} or {@link com.sleepycat.je.Cursor Cursor} methods, the results are undefined.
DatabaseEntry objects may be used in conjunction with the object mapping support provided in the {@link com.sleepycat.bind} package.
Input and Output Parameters

DatabaseEntry objects are used for both input data (when writing to a database or specifying a search parameter) and output data (when reading from a database). For certain methods, one parameter may be an input parameter and another may be an output parameter. For example, the {@link Database#get} method has an input key parameter and an output dataparameter. The documentation for each method describes whether its parameters are input or output parameters.

For DatabaseEntry input parameters, the caller is responsible for initializing the data array of the DatabaseEntry. For DatabaseEntry output parameters, the method called will initialize the data array.

Also note that for DatabaseEntry output parameters, the method called will always allocate a new byte array. The byte array specified by the caller will not be used. Therefore, after calling a method that returns output parameters, the application can safely keep a reference to the byte array returned by {@link #getData} without danger that the array will beoverwritten in a subsequent call.

Offset and Size Properties

By default the Offset property is zero and the Size property is the length of the byte array. However, to allow for optimizations involving the partial use of a byte array, the Offset and Size may be set to non-default values.

For DatabaseEntry output parameters, the Size will always be set to the length of the byte array and the Offset will always be set to zero.

However, for DatabaseEntry input parameters the Offset and Size are set to non-default values by the built-in tuple and serial bindings. For example, with a tuple or serial binding the byte array is grown dynamically as data is output, and the Size is set to the number of bytes actually used. For a serial binding, the Offset is set to a non-zero value in order to implement an optimization having to do with the serialization stream header.

Therefore, for output DatabaseEntry parameters the application can assume that the Offset is zero and the Size is the length of the byte array. However, for input DatabaseEntry parameters the application should not make this assumption. In general, it is safest for the application to always honor the Size and Offset properties, rather than assuming they have default values.

Partial Offset and Length Properties

By default the specified data (byte array, offset and size) corresponds to the full stored key or data item. Optionally, the Partial property can be set to true, and the PartialOffset and PartialLength properties are used to specify the portion of the key or data item to be read or written. For details, see the {@link #setPartial(int,int,boolean)} method.
Note that the Partial properties are set only by the caller. They will never be set by a Database or Cursor method, nor will they every be set by bindings. Therefore, the application can assume that the Partial properties are not set, unless the application itself sets them explicitly.

See Using Partial DatabaseEntry Parameters for more information.

                            UUID id = UUIDGenerator.generateQueueUUID(enqueue.getQueueName(), virtualHostName);
                            newEnqueues[i] = new NewRecordImpl(id, enqueue.getMessageNumber());
                        }
                    }
                    NewPreparedTransaction newPreparedTransaction = new NewPreparedTransaction(newEnqueues, newDequeues);
                    DatabaseEntry newValue = new DatabaseEntry();
                    newTransactionBinding.objectToEntry(newPreparedTransaction, newValue);
                    put(newXidDatabase, transaction, key, newValue);
                }
            };
            new DatabaseTemplate(environment, OLD_XID_DB_NAME, NEW_XID_DB_NAME, transaction).run(xidEntriesCursor);

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                {
                    OldQueueEntryKey oldEntryRecord = oldBinding.entryToObject(key);
                    UUID queueId = UUIDGenerator.generateQueueUUID(oldEntryRecord.getQueueName().asString(), virtualHostName);


                    NewQueueEntryKey newEntryRecord = new NewQueueEntryKey(queueId, oldEntryRecord.getMessageId());
                    DatabaseEntry newKey = new DatabaseEntry();
                    newBinding.objectToEntry(newEntryRecord, newKey);
                    put(newDeliveryDatabase, transaction, newKey, value);
                }
            };
            new DatabaseTemplate(environment, OLD_DELIVERY_DB_NAME, NEW_DELIVERY_DB_NAME, transaction)

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    }


    private void storeConfiguredObjectEntry(Database configuredObjectsDatabase, UUID id,
            UpgradeConfiguredObjectRecord configuredObject, Transaction transaction)
    {
        DatabaseEntry key = new DatabaseEntry();
        DatabaseEntry value = new DatabaseEntry();
        UpgradeUUIDBinding uuidBinding = new UpgradeUUIDBinding();
        uuidBinding.objectToEntry(id, key);
        ConfiguredObjectBinding configuredBinding = new ConfiguredObjectBinding();
        configuredBinding.objectToEntry(configuredObject, value);
        put(configuredObjectsDatabase, transaction, key, value);

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        }
    }


    private void assertXidEntries(Environment environment)
    {
        final DatabaseEntry value = new DatabaseEntry();
        final DatabaseEntry key = getXidKey();
        new DatabaseTemplate(environment, NEW_XID_DB_NAME, null).run(new DatabaseRunnable()
        {


            @Override
            public void run(Database xidDatabase, Database nullDatabase, Transaction transaction)

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    }


    private void populateOldXidEntries(Environment environment)
    {


        final DatabaseEntry value = new DatabaseEntry();
        OldRecordImpl[] enqueues = { new OldRecordImpl("TEST1", 1) };
        OldRecordImpl[] dequeues = { new OldRecordImpl("TEST2", 2) };
        OldPreparedTransaction oldPreparedTransaction = new OldPreparedTransaction(enqueues, dequeues);
        OldPreparedTransactionBinding oldPreparedTransactionBinding = new OldPreparedTransactionBinding();
        oldPreparedTransactionBinding.objectToEntry(oldPreparedTransaction, value);


        final DatabaseEntry key = getXidKey();
        new DatabaseTemplate(environment, OLD_XID_DB_NAME, null).run(new DatabaseRunnable()
        {


            @Override
            public void run(Database xidDatabase, Database nullDatabase, Transaction transaction)

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        });
    }


    protected DatabaseEntry getXidKey()
    {
        final DatabaseEntry value = new DatabaseEntry();
        byte[] globalId = { 1 };
        byte[] branchId = { 2 };
        Xid xid = new Xid(1l, globalId, branchId);
        XidBinding xidBinding = XidBinding.getInstance();
        xidBinding.objectToEntry(xid, value);

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            {
                CompoundKeyBinding binding = new CompoundKeyBinding();
                CompoundKey originalCompoundKey = binding.entryToObject(key);
                int corruptedOffset = originalCompoundKey.getOffset() + 2;
                CompoundKey corruptedCompoundKey = new CompoundKey(originalCompoundKey.getMessageId(), corruptedOffset);
                DatabaseEntry newKey = new DatabaseEntry();
                binding.objectToEntry(corruptedCompoundKey, newKey);


                _logger.info("Deliberately corrupted message id " + originalCompoundKey.getMessageId()
                        + ", changed offset from " + originalCompoundKey.getOffset() + " to "
                        + corruptedCompoundKey.getOffset());

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        Cursor cursor = null;
        try
        {
            versionDb = _environment.openDatabase(null, Upgrader.VERSION_DB_NAME, dbConfig);
            cursor = versionDb.openCursor(null, null);
            DatabaseEntry key = new DatabaseEntry();
            DatabaseEntry value = new DatabaseEntry();
            while (cursor.getNext(key, value, null) == OperationStatus.SUCCESS)
            {
                int version = IntegerBinding.entryToInt(key);
                if (storeVersion < version)
                {

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                final int fj = j;
                results.add(service.submit(new Callable<Object>() {


                    public Object call() throws Exception {
                        db.put(null,
                               new DatabaseEntry(Integer.toString(fi * increment + fj).getBytes()),
                               new DatabaseEntry(Integer.toString(fi * increment + fj).getBytes()));
                        return null;
                    }
                }));
            }
            for(int j = 0; j < increment; j++)
                results.get(j).get();
            writeTimes[i] = System.currentTimeMillis() - startTime;
            System.out.println("write: " + (writeTimes[i] / (double) increment));
            results.clear();


            startTime = System.currentTimeMillis();
            for(int j = 0; j < increment; j++) {
                results.add(service.submit(new Callable<Object>() {


                    public Object call() throws Exception {
                        int value = rand.nextInt((fi + 1) * increment);
                        return db.get(null,
                                      new DatabaseEntry(Integer.toString(value).getBytes()),
                                      new DatabaseEntry(Integer.toString(value).getBytes()),
                                      null);
                    }
                }));
            }
            for(int j = 0; j < increment; j++)

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         * Fetches the next entry from the DB, for the partition
         * 
         * @return true if some new data was fetched, false if end of data
         */
        private boolean makeMore() {
            DatabaseEntry keyEntry = new DatabaseEntry();
            DatabaseEntry valueEntry = new DatabaseEntry();
            OperationStatus status;
            try {
                if(!positioned) {
                    positioned = true;
                    keyEntry.setData(StoreBinaryFormat.makePartitionKey(partition));
                    status = cursor.getSearchKeyRange(keyEntry,
                                                      valueEntry,
                                                      LockMode.READ_UNCOMMITTED);
                } else {
                    status = cursor.getNext(keyEntry, valueEntry, LockMode.READ_UNCOMMITTED);
                }


                if(OperationStatus.NOTFOUND == status) {
                    // we have reached the end of the cursor
                    return false;
                }


                // check if we are still in the same partition we need
                if(StoreBinaryFormat.extractPartition(keyEntry.getData()) != partition)
                    return false;


                ByteArray key = new ByteArray(StoreBinaryFormat.extractKey(keyEntry.getData()));
                for(Versioned<byte[]> val: StoreBinaryFormat.fromByteArray(valueEntry.getData()))
                    this.cache.add(Pair.create(key, val));
                return true;
            } catch(DatabaseException e) {
                bdbEngine.bdbEnvironmentStats.reportException(e);
                logger.error(e);

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Examples of com.sleepycat.je.DatabaseEntry

Input and Output Parameters

Offset and Size Properties

Partial Offset and Length Properties

Related Classes of com.sleepycat.je.DatabaseEntry