/*
* The Alluxio Open Foundation licenses this work under the Apache License, version 2.0
* (the "License"). You may not use this work except in compliance with the License, which is
* available at www.apache.org/licenses/LICENSE-2.0
*
* This software is distributed on an "AS IS" basis, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
* either express or implied, as more fully set forth in the License.
*
* See the NOTICE file distributed with this work for information regarding copyright ownership.
*/
package alluxio.master.journal.ufs;
import alluxio.underfs.UfsStatus;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import javax.annotation.concurrent.ThreadSafe;
/**
* This class provides a snapshot of everything in the journal and some utility methods.
*/
@ThreadSafe
final class UfsJournalSnapshot {
/** The committed checkpoints. */
private final List<UfsJournalFile> mCheckpoints;
/** The journal edit logs including the incomplete log. */
private final List<UfsJournalFile> mLogs;
/** The temporary checkpoint files. */
private final List<UfsJournalFile> mTemporaryCheckpoints;
/**
* Creates an instance of the journal snapshot.
*
* @param checkpoints the checkpoints
* @param logs the logs including the incomplete log
* @param temporaryCheckpoints the temporary checkpoint files
*/
private UfsJournalSnapshot(List<UfsJournalFile> checkpoints, List<UfsJournalFile> logs,
List<UfsJournalFile> temporaryCheckpoints) {
mCheckpoints = checkpoints;
mLogs = logs;
mTemporaryCheckpoints = temporaryCheckpoints;
}
/**
* @return the checkpoints sorted by end sequence number increasingly
*/
List<UfsJournalFile> getCheckpoints() {
return mCheckpoints;
}
/**
* @return the latest checkpoint, null if no checkpoint exists
*/
UfsJournalFile getLatestCheckpoint() {
if (!mCheckpoints.isEmpty()) {
return mCheckpoints.get(mCheckpoints.size() - 1);
}
return null;
}
/**
* @return the logs sorted by the end sequence number increasingly
*/
List<UfsJournalFile> getLogs() {
return mLogs;
}
/**
* @return the temporary checkpoints
*/
List<UfsJournalFile> getTemporaryCheckpoints() {
return mTemporaryCheckpoints;
}
/**
* Creates a snapshot of the journal.
*
* @return the journal snapshot
*/
static UfsJournalSnapshot getSnapshot(UfsJournal journal) throws IOException {
// Checkpoints.
List<UfsJournalFile> checkpoints = new ArrayList<>();
UfsStatus[] statuses = journal.getUfs().listStatus(journal.getCheckpointDir().toString());
if (statuses != null) {
for (UfsStatus status : statuses) {
UfsJournalFile file = UfsJournalFile.decodeCheckpointFile(journal, status.getName());
if (file != null) {
checkpoints.add(file);
}
}
Collections.sort(checkpoints);
}
List<UfsJournalFile> logs = new ArrayList<>();
statuses = journal.getUfs().listStatus(journal.getLogDir().toString());
if (statuses != null) {
for (UfsStatus status : statuses) {
UfsJournalFile file = UfsJournalFile.decodeLogFile(journal, status.getName());
if (file != null) {
logs.add(file);
}
}
Collections.sort(logs);
}
List<UfsJournalFile> tmpCheckpoints = new ArrayList<>();
statuses = journal.getUfs().listStatus(journal.getTmpDir().toString());
if (statuses != null) {
for (UfsStatus status : statuses) {
tmpCheckpoints.add(UfsJournalFile.decodeTemporaryCheckpointFile(journal, status.getName()));
}
}
return new UfsJournalSnapshot(checkpoints, logs, tmpCheckpoints);
}
/**
* Gets the current log (the incomplete log) that is being written to.
*
* @return the current log
*/
static UfsJournalFile getCurrentLog(UfsJournal journal) throws IOException {
List<UfsJournalFile> logs = new ArrayList<>();
UfsStatus[] statuses = journal.getUfs().listStatus(journal.getLogDir().toString());
if (statuses != null) {
for (UfsStatus status : statuses) {
UfsJournalFile file = UfsJournalFile.decodeLogFile(journal, status.getName());
if (file != null) {
logs.add(file);
}
}
if (!logs.isEmpty()) {
UfsJournalFile file = Collections.max(logs);
if (file.isIncompleteLog()) {
return file;
}
}
}
return null;
}
/**
* Gets the first journal log sequence number that is not yet checkpointed.
*
* @return the first journal log sequence number that is not yet checkpointed
*/
static long getNextLogSequenceNumberToCheckpoint(UfsJournal journal) throws IOException {
List<UfsJournalFile> checkpoints = new ArrayList<>();
UfsStatus[] statuses = journal.getUfs().listStatus(journal.getCheckpointDir().toString());
if (statuses != null) {
for (UfsStatus status : statuses) {
UfsJournalFile file = UfsJournalFile.decodeCheckpointFile(journal, status.getName());
if (file != null) {
checkpoints.add(file);
}
}
Collections.sort(checkpoints);
}
if (checkpoints.isEmpty()) {
return 0;
}
return checkpoints.get(checkpoints.size() - 1).getEnd();
}
}