/**
* Create the voldemort key and value from the input key and value and map it out for each of the
* responsible voldemort nodes
*
* <p>The output key is the md5 of the serialized key returned by makeKey(). The output value is
* the node_id & partition_id of the responsible node followed by serialized value returned by
* makeValue() OR if we have setKeys flag on the serialized key and serialized value
*/
public void map(
K key, V value, OutputCollector<BytesWritable, BytesWritable> output, Reporter reporter)
throws IOException {
byte[] keyBytes = keySerializer.toBytes(makeKey(key, value));
byte[] valBytes = valueSerializer.toBytes(makeValue(key, value));
// Compress key and values if required
if (keySerializerDefinition.hasCompression()) {
keyBytes = keyCompressor.deflate(keyBytes);
}
if (valueSerializerDefinition.hasCompression()) {
valBytes = valueCompressor.deflate(valBytes);
}
// Get the output byte arrays ready to populate
byte[] outputValue;
BytesWritable outputKey;
// Leave initial offset for (a) node id (b) partition id
// since they are written later
int offsetTillNow = 2 * ByteUtils.SIZE_OF_INT;
// In order - 4 ( for node id ) + 4 ( partition id ) + 1 ( replica
// type - primary | secondary | tertiary... ] + 4 ( key size )
// size ) + 4 ( value size ) + key + value
outputValue =
new byte
[valBytes.length
+ keyBytes.length
+ ByteUtils.SIZE_OF_BYTE
+ 4 * ByteUtils.SIZE_OF_INT];
// Write key length - leave byte for replica type
offsetTillNow += ByteUtils.SIZE_OF_BYTE;
ByteUtils.writeInt(outputValue, keyBytes.length, offsetTillNow);
// Write value length
offsetTillNow += ByteUtils.SIZE_OF_INT;
ByteUtils.writeInt(outputValue, valBytes.length, offsetTillNow);
// Write key
offsetTillNow += ByteUtils.SIZE_OF_INT;
System.arraycopy(keyBytes, 0, outputValue, offsetTillNow, keyBytes.length);
// Write value
offsetTillNow += keyBytes.length;
System.arraycopy(valBytes, 0, outputValue, offsetTillNow, valBytes.length);
// Generate MR key - 16 byte md5
outputKey = new BytesWritable(keyBytes);
// Generate partition and node list this key is destined for
List<Integer> partitionList = routingStrategy.getPartitionList(keyBytes);
Node[] partitionToNode = routingStrategy.getPartitionToNode();
for (int replicaType = 0; replicaType < partitionList.size(); replicaType++) {
// Node id
ByteUtils.writeInt(outputValue, partitionToNode[partitionList.get(replicaType)].getId(), 0);
// Primary partition id
ByteUtils.writeInt(outputValue, partitionList.get(0), ByteUtils.SIZE_OF_INT);
// Replica type
ByteUtils.writeBytes(
outputValue, replicaType, 2 * ByteUtils.SIZE_OF_INT, ByteUtils.SIZE_OF_BYTE);
BytesWritable outputVal = new BytesWritable(outputValue);
output.collect(outputKey, outputVal);
}
}
