private DataNodeIdentifier pickReplacement(
SegmentGroup affectedGroup, DataNodeIdentifier oldNode) {
DataNodeIdentifier replacementNode = null;
List<DataNodeStatusPair> removedPairs = new ArrayList<DataNodeStatusPair>();
while (replacementNode == null) {
DataNodeStatusPair next = datanodeStatuses.poll();
removedPairs.add(next);
DataNodeIdentifier nextId = next.getIdentifier();
if (!nextId.equals(oldNode) && !affectedGroup.isMember(nextId)) {
replacementNode = nextId;
}
}
for (DataNodeStatusPair each : removedPairs) {
datanodeStatuses.add(each);
}
return replacementNode;
}
protected void reconfigureSegmentGroup(
SegmentGroup affectedGroup,
DataNodeIdentifier oldNode,
DataNodeIdentifier replacementNode,
boolean oldNodeIsUp) {
System.out.println("Reconfiguring");
/* what do we do? this is what we do...
note: we do NOT worry about the status of the node here; we assume that is set by the coordinator
for each segment in the segment group:
if (oldNodeIsUp):
send an unset-segment request
perform a read on the segment group
send a write request to the new node
swap the new node into the segment group
*/
int volumeId = affectedGroup.getVolumeId();
long startingOffset = affectedGroup.getStartingBlock();
long stoppingOffset = affectedGroup.getStoppingBlock();
if (oldNodeIsUp) {
List<DataNodeIdentifier> targets = new ArrayList<DataNodeIdentifier>();
targets.add(oldNode);
int unsetId =
coordinator
.getServer()
.issueUnsetSegmentRequest(targets, volumeId, startingOffset, stoppingOffset);
boolean waiting = true;
while (waiting) {
List<UnsetSegmentRequestResult> results =
coordinator.getServer().getUnsetSegmentRequestResults(unsetId);
if (results.get(0).wasSuccessful()) {
waiting = false;
}
}
}
List<DataNodeIdentifier> replacementMembers =
new ArrayList<DataNodeIdentifier>(affectedGroup.getMembers());
int oldNodeIndex = replacementMembers.indexOf(oldNode);
replacementMembers.set(oldNodeIndex, replacementNode);
SegmentGroup replacementGroup =
new SegmentGroup(replacementMembers, volumeId, startingOffset, stoppingOffset);
for (long offset = startingOffset; offset <= stoppingOffset; ++offset)
// TODO FIXME eventual improvement: make this whole loop asynchronous
// that is, issue each read request, then as the results come in, issue the write requests
{
int readId = coordinator.read(volumeId, logicalOffset);
while (!coordinator.requestFinished(readId)) {
// spin!!!
}
ReadRequestResult readResult = coordinator.readResult(readId);
byte[] block = readResult.getBlock();
int writeId = coordinator.writeWithTarget(replacementGroup, volumeId, offset, block);
while (!coordinator.requestFinished(writeId)) {
// spin!!!
}
// TODO FIXME check for success of the read (above) and the write (here)
}
affectedGroup.replace(oldNode, replacementNode);
}