/** Pairs up given nodes in balancing plan */
private void scheduleTask(Source source, long size, Target target) {
NodeTask nodeTask = new NodeTask(target, size);
source.addNodeTask(nodeTask);
target.addNodeTask(nodeTask);
sources.add(source);
targets.add(target);
LOG.info("scheduled " + size + " bytes : " + source.getName() + " -> " + target.getName());
}
/** Updates the plan with all pairs of nodes from this bucket which need to be connected */
public void updatePlan() {
while (!this.sources.isEmpty() && !this.targets.isEmpty()) {
Source source = this.sources.poll();
Target target = this.targets.poll();
if (!wasUrgent(source) && !wasUrgent(target)) {
// Due to ordering of DataNodes we can skip the rest
break;
}
long size = moveSize(source, target);
if (size > 0) {
scheduleTask(source, size, target);
}
if (source.getAvailableMoveSize() > 0) {
this.sources.add(source);
}
if (target.getAvailableMoveSize() > 0) {
this.targets.add(target);
}
// Loop termination:
// In each step we either scheduleTask, therefore decreasing sum (over
// all nodes) of availableMoveSize, or decrease number of nodes in
// sources or targets queue, all of them are bounded by 0.
}
}
/** Determines how much data to move between given nodes */
private long moveSize(Source source, BalancerDatanode target) {
// TODO balancing concurrency
return Math.min(source.getAvailableMoveSize(), target.getAvailableMoveSize());
}