Example usage for org.apache.hadoop.record Buffer setCapacity

Introduction

In this page you can find the example usage for org.apache.hadoop.record Buffer setCapacity.

Prototype

public void setCapacity(int newCapacity) 

Source Link

Document

Change the capacity of the backing storage.

Usage

From source file:org.commoncrawl.util.TimeSeriesDataFile.java

License:Open Source License

private void doCommonRead(ArrayList<KeyValueTuple<Long, ValueType>> valuesOut, RandomAccessFile file,
        long headerOffset, long endOfPrevRecord, int currentRecordLength, int recordsToRead,
        long optionalMinKeyValue) throws IOException {

    Buffer recordBuffer = new Buffer();
    DataInputBuffer inputBuffer = new DataInputBuffer();

    // ok start walking backwards ... 
    while (recordsToRead != 0) {
        // setup new previous record pos pointer  
        endOfPrevRecord = endOfPrevRecord - currentRecordLength - 4;
        // and seek to it endOfLastRecord - 4
        file.seek(endOfPrevRecord - 4);//  w  ww.j av a  2s. c om

        recordBuffer.setCapacity(currentRecordLength + 8);
        // read in proper amount of data ...
        file.read(recordBuffer.get(), 0, currentRecordLength + 8);
        // ok initialize input buffer ... 
        inputBuffer.reset(recordBuffer.get(), currentRecordLength + 8);
        // now read next record length first ... 
        int nextRecordLength = inputBuffer.readInt();
        // next read sync bytes ... 
        int syncBytes = inputBuffer.readInt();
        // validate 
        if (syncBytes != SyncBytes) {
            throw new IOException("Corrupt Record Detected!");
        }
        // ok read real record bytes ... 
        int realRecordBytes = inputBuffer.readInt();
        // read crc ... 
        long crcValue = inputBuffer.readLong();
        // ok validate crc ...  
        crc.reset();
        crc.update(inputBuffer.getData(), inputBuffer.getPosition(), realRecordBytes - 8);
        if (crcValue != crc.getValue()) {
            throw new IOException("CRC Mismatch!");
        }
        // ok now read key and value 
        try {
            long key = WritableUtils.readVLong(inputBuffer);

            if (optionalMinKeyValue != -1 && key < optionalMinKeyValue) {
                break;
            }

            ValueType value = (ValueType) valueClass.newInstance();
            value.readFields(inputBuffer);
            KeyValueTuple tuple = new KeyValueTuple<Long, ValueType>(key, value);
            tuple.recordPos = endOfPrevRecord;
            valuesOut.add(0, tuple);

        } catch (Exception e) {
            throw new IOException(e);
        }

        currentRecordLength = nextRecordLength;

        recordsToRead--;

        if (endOfPrevRecord == headerOffset)
            break;
    }
}

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