/**
* Check if the specified snapshot is done
*
* @param expected
* @return true if snapshot is ready to be restored, false if it is still being taken.
* @throws IOException IOException if error from HDFS or RPC
* @throws UnknownSnapshotException if snapshot is invalid or does not exist.
*/
public boolean isSnapshotDone(SnapshotDescription expected) throws IOException {
// check the request to make sure it has a snapshot
if (expected == null) {
throw new UnknownSnapshotException(
"No snapshot name passed in request, can't figure out which snapshot you want to check.");
}
String ssString = ClientSnapshotDescriptionUtils.toString(expected);
// check to see if the sentinel exists,
// and if the task is complete removes it from the in-progress snapshots map.
SnapshotSentinel handler = removeSentinelIfFinished(this.snapshotHandlers, expected);
// stop tracking "abandoned" handlers
cleanupSentinels();
if (handler == null) {
// If there's no handler in the in-progress map, it means one of the following:
// - someone has already requested the snapshot state
// - the requested snapshot was completed long time ago (cleanupSentinels() timeout)
// - the snapshot was never requested
// In those cases returns to the user the "done state" if the snapshots exists on disk,
// otherwise raise an exception saying that the snapshot is not running and doesn't exist.
if (!isSnapshotCompleted(expected)) {
throw new UnknownSnapshotException(
"Snapshot "
+ ssString
+ " is not currently running or one of the known completed snapshots.");
}
// was done, return true;
return true;
}
// pass on any failure we find in the sentinel
try {
handler.rethrowExceptionIfFailed();
} catch (ForeignException e) {
// Give some procedure info on an exception.
String status;
Procedure p = coordinator.getProcedure(expected.getName());
if (p != null) {
status = p.getStatus();
} else {
status = expected.getName() + " not found in proclist " + coordinator.getProcedureNames();
}
throw new HBaseSnapshotException(
"Snapshot " + ssString + " had an error. " + status,
e,
ProtobufUtil.createSnapshotDesc(expected));
}
// check to see if we are done
if (handler.isFinished()) {
LOG.debug("Snapshot '" + ssString + "' has completed, notifying client.");
return true;
} else if (LOG.isDebugEnabled()) {
LOG.debug("Snapshoting '" + ssString + "' is still in progress!");
}
return false;
}
/**
* Remove the sentinels that are marked as finished and the completion time has exceeded the
* removal timeout.
*
* @param sentinels map of sentinels to clean
*/
private synchronized void cleanupSentinels(final Map<TableName, SnapshotSentinel> sentinels) {
long currentTime = EnvironmentEdgeManager.currentTime();
Iterator<Map.Entry<TableName, SnapshotSentinel>> it = sentinels.entrySet().iterator();
while (it.hasNext()) {
Map.Entry<TableName, SnapshotSentinel> entry = it.next();
SnapshotSentinel sentinel = entry.getValue();
if (sentinel.isFinished()
&& (currentTime - sentinel.getCompletionTimestamp())
> SNAPSHOT_SENTINELS_CLEANUP_TIMEOUT) {
it.remove();
}
}
}
/**
* 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;
}
@Override
public void stop(String why) {
// short circuit
if (this.stopped) return;
// make sure we get stop
this.stopped = true;
// pass the stop onto take snapshot handlers
for (SnapshotSentinel snapshotHandler : this.snapshotHandlers.values()) {
snapshotHandler.cancel(why);
}
try {
if (coordinator != null) {
coordinator.close();
}
} catch (IOException e) {
LOG.error("stop ProcedureCoordinator error", e);
}
}
/**
* 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;
}
/**
* Check to see if the specified table has a snapshot in progress. Currently we have a limitation
* only allowing a single snapshot per table at a time.
*
* @param tableName name of the table being snapshotted.
* @return <tt>true</tt> if there is a snapshot in progress on the specified table.
*/
synchronized boolean isTakingSnapshot(final TableName tableName) {
SnapshotSentinel handler = this.snapshotHandlers.get(tableName);
return handler != null && !handler.isFinished();
}
