/**
* Check to make sure that we are OK to run the passed snapshot. Checks to make sure that we
* aren't already running a snapshot or restore on the requested table.
*
* @param snapshot description of the snapshot we want to start
* @throws HBaseSnapshotException if the filesystem could not be prepared to start the snapshot
*/
private synchronized void prepareToTakeSnapshot(SnapshotDescription snapshot)
throws HBaseSnapshotException {
FileSystem fs = master.getMasterFileSystem().getFileSystem();
Path workingDir = SnapshotDescriptionUtils.getWorkingSnapshotDir(snapshot, rootDir);
TableName snapshotTable = TableName.valueOf(snapshot.getTable());
// make sure we aren't already running a snapshot
if (isTakingSnapshot(snapshot)) {
SnapshotSentinel handler = this.snapshotHandlers.get(snapshotTable);
throw new SnapshotCreationException(
"Rejected taking "
+ ClientSnapshotDescriptionUtils.toString(snapshot)
+ " because we are already running another snapshot "
+ (handler != null
? ("on the same table "
+ ClientSnapshotDescriptionUtils.toString(handler.getSnapshot()))
: "with the same name"),
ProtobufUtil.createSnapshotDesc(snapshot));
}
// make sure we aren't running a restore on the same table
if (isRestoringTable(snapshotTable)) {
throw new SnapshotCreationException(
"Rejected taking "
+ ClientSnapshotDescriptionUtils.toString(snapshot)
+ " because we are already have a restore in progress on the same snapshot.");
}
try {
// delete the working directory, since we aren't running the snapshot. Likely leftovers
// from a failed attempt.
fs.delete(workingDir, true);
// recreate the working directory for the snapshot
if (!fs.mkdirs(workingDir)) {
throw new SnapshotCreationException(
"Couldn't create working directory (" + workingDir + ") for snapshot",
ProtobufUtil.createSnapshotDesc(snapshot));
}
} catch (HBaseSnapshotException e) {
throw e;
} catch (IOException e) {
throw new SnapshotCreationException(
"Exception while checking to see if snapshot could be started.",
e,
ProtobufUtil.createSnapshotDesc(snapshot));
}
}
/**
* Check to see if there is a snapshot in progress with the same name or on the same table.
* Currently we have a limitation only allowing a single snapshot per table at a time. Also we
* don't allow snapshot with the same name.
*
* @param snapshot description of the snapshot being checked.
* @return <tt>true</tt> if there is a snapshot in progress with the same name or on the same
* table.
*/
synchronized boolean isTakingSnapshot(final SnapshotDescription snapshot) {
TableName snapshotTable = TableName.valueOf(snapshot.getTable());
if (isTakingSnapshot(snapshotTable)) {
return true;
}
Iterator<Map.Entry<TableName, SnapshotSentinel>> it =
this.snapshotHandlers.entrySet().iterator();
while (it.hasNext()) {
Map.Entry<TableName, SnapshotSentinel> entry = it.next();
SnapshotSentinel sentinel = entry.getValue();
if (snapshot.getName().equals(sentinel.getSnapshot().getName()) && !sentinel.isFinished()) {
return true;
}
}
return false;
}
/**
* Return the handler if it is currently live and has the same snapshot target name. The handler
* is removed from the sentinels map if completed.
*
* @param sentinels live handlers
* @param snapshot snapshot description
* @return null if doesn't match, else a live handler.
*/
private synchronized SnapshotSentinel removeSentinelIfFinished(
final Map<TableName, SnapshotSentinel> sentinels, final SnapshotDescription snapshot) {
if (!snapshot.hasTable()) {
return null;
}
TableName snapshotTable = TableName.valueOf(snapshot.getTable());
SnapshotSentinel h = sentinels.get(snapshotTable);
if (h == null) {
return null;
}
if (!h.getSnapshot().getName().equals(snapshot.getName())) {
// specified snapshot is to the one currently running
return null;
}
// Remove from the "in-progress" list once completed
if (h.isFinished()) {
sentinels.remove(snapshotTable);
}
return h;
}