@VisibleForTesting
boolean computeReplicationWorkForBlock(Block block, int priority) {
int requiredReplication, numEffectiveReplicas;
List<DatanodeDescriptor> containingNodes, liveReplicaNodes;
DatanodeDescriptor srcNode;
INodeFile fileINode = null;
int additionalReplRequired;
namesystem.writeLock();
try {
synchronized (neededReplications) {
// block should belong to a file
fileINode = blocksMap.getINode(block);
// abandoned block or block reopened for append
if(fileINode == null || fileINode.isUnderConstruction()) {
neededReplications.remove(block, priority); // remove from neededReplications
replIndex--;
return false;
}
requiredReplication = fileINode.getReplication();
// get a source data-node
containingNodes = new ArrayList<DatanodeDescriptor>();
liveReplicaNodes = new ArrayList<DatanodeDescriptor>();
NumberReplicas numReplicas = new NumberReplicas();
srcNode = chooseSourceDatanode(
block, containingNodes, liveReplicaNodes, numReplicas);
if(srcNode == null) // block can not be replicated from any node
return false;
assert liveReplicaNodes.size() == numReplicas.liveReplicas();
// do not schedule more if enough replicas is already pending
numEffectiveReplicas = numReplicas.liveReplicas() +
pendingReplications.getNumReplicas(block);
if (numEffectiveReplicas >= requiredReplication) {
if ( (pendingReplications.getNumReplicas(block) > 0) ||
(blockHasEnoughRacks(block)) ) {
neededReplications.remove(block, priority); // remove from neededReplications
replIndex--;
NameNode.stateChangeLog.info("BLOCK* "
+ "Removing block " + block
+ " from neededReplications as it has enough replicas.");
return false;
}
}
if (numReplicas.liveReplicas() < requiredReplication) {
additionalReplRequired = requiredReplication - numEffectiveReplicas;
} else {
additionalReplRequired = 1; //Needed on a new rack
}
}
} finally {
namesystem.writeUnlock();
}
// Exclude all of the containing nodes from being targets.
// This list includes decommissioning or corrupt nodes.
HashMap<Node, Node> excludedNodes = new HashMap<Node, Node>();
for (DatanodeDescriptor dn : containingNodes) {
excludedNodes.put(dn, dn);
}
// choose replication targets: NOT HOLDING THE GLOBAL LOCK
// It is costly to extract the filename for which chooseTargets is called,
// so for now we pass in the Inode itself.
DatanodeDescriptor targets[] =
blockplacement.chooseTarget(fileINode, additionalReplRequired,
srcNode, liveReplicaNodes, excludedNodes, block.getNumBytes());
if(targets.length == 0)
return false;
namesystem.writeLock();
try {
synchronized (neededReplications) {
// Recheck since global lock was released
// block should belong to a file
fileINode = blocksMap.getINode(block);
// abandoned block or block reopened for append
if(fileINode == null || fileINode.isUnderConstruction()) {
neededReplications.remove(block, priority); // remove from neededReplications
replIndex--;
return false;
}
requiredReplication = fileINode.getReplication();
// do not schedule more if enough replicas is already pending
NumberReplicas numReplicas = countNodes(block);
numEffectiveReplicas = numReplicas.liveReplicas() +
pendingReplications.getNumReplicas(block);