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// Copyright Verizon Media. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
package com.yahoo.vespa.curator.stats;
import com.yahoo.jdisc.Metric;
import com.yahoo.vespa.curator.Lock;
import java.time.Duration;
import java.util.List;
import java.util.Optional;
import java.util.concurrent.ConcurrentLinkedDeque;
import java.util.function.Consumer;
/**
* This class manages thread-specific statistics and information related to acquiring and releasing
* {@link Lock}. Instances of this class contain information tied to a specific thread and lock path.
*
* <p>Instances of this class are thread-safe as long as foreign threads (!= this.thread) avoid mutable methods.</p>
*
* @author hakon
*/
public class ThreadLockStats {
private final Thread thread;
/**
* The locks are reentrant so there may be more than 1 lock for this thread:
* The first LockAttempt in lockAttemptsStack was the first and top-most lock that was acquired.
*/
private final ConcurrentLinkedDeque<LockAttempt> lockAttemptsStack = new ConcurrentLinkedDeque<>();
/** Non-empty if there is an ongoing recording for this thread. */
private volatile Optional<RecordedLockAttempts> ongoingRecording = Optional.empty();
ThreadLockStats(Thread currentThread) {
this.thread = currentThread;
}
public String getThreadName() { return thread.getName(); }
public String getStackTrace() {
var stackTrace = new StringBuilder();
StackTraceElement[] elements = thread.getStackTrace();
for (int i = 0; i < elements.length; ++i) {
var element = elements[i];
stackTrace.append(element.getClassName())
.append('.')
.append(element.getMethodName())
.append('(')
.append(element.getFileName())
.append(':')
.append(element.getLineNumber())
.append(")\n");
}
return stackTrace.toString();
}
public List<LockAttempt> getOngoingLockAttempts() { return List.copyOf(lockAttemptsStack); }
public Optional<LockAttempt> getTopMostOngoingLockAttempt() { return lockAttemptsStack.stream().findFirst(); }
public Optional<RecordedLockAttempts> getOngoingRecording() { return ongoingRecording; }
/** Mutable method (see class doc) */
public void invokingAcquire(String lockPath, Duration timeout,
Optional<Metric> metric, Optional<Metric.Context> metricContext) {
LockCounters lockCounters = getGlobalLockCounters(lockPath);
lockCounters.invokeAcquireCount.incrementAndGet();
lockCounters.inCriticalRegionCount.incrementAndGet();
LockAttempt lockAttempt = LockAttempt.invokingAcquire(this, lockPath, timeout, metric, metricContext);
LockAttempt lastLockAttempt = lockAttemptsStack.peekLast();
if (lastLockAttempt == null) {
ongoingRecording.ifPresent(recording -> recording.addTopLevelLockAttempt(lockAttempt));
} else {
lastLockAttempt.addNestedLockAttempt(lockAttempt);
}
lockAttemptsStack.addLast(lockAttempt);
}
/** Mutable method (see class doc) */
public void acquireFailed(String lockPath) {
LockCounters lockCounters = getGlobalLockCounters(lockPath);
lockCounters.acquireFailedCount.incrementAndGet();
removeLastLockAttempt(lockCounters, LockAttempt::acquireFailed);
}
/** Mutable method (see class doc) */
public void acquireTimedOut(String lockPath) {
LockCounters lockCounters = getGlobalLockCounters(lockPath);
lockCounters.acquireTimedOutCount.incrementAndGet();
removeLastLockAttempt(lockCounters, LockAttempt::timedOut);
}
/** Mutable method (see class doc) */
public void lockAcquired(String lockPath) {
getGlobalLockCounters(lockPath).lockAcquiredCount.incrementAndGet();
LockAttempt lockAttempt = lockAttemptsStack.peekLast();
if (lockAttempt == null) {
throw new IllegalStateException("lockAcquired invoked without lockAttempts");
}
lockAttempt.lockAcquired();
}
/** Mutable method (see class doc) */
public void lockReleased(String lockPath) {
LockCounters lockCounters = getGlobalLockCounters(lockPath);
lockCounters.locksReleasedCount.incrementAndGet();
removeLastLockAttempt(lockCounters, LockAttempt::released);
}
/** Mutable method (see class doc) */
public void lockReleaseFailed(String lockPath) {
LockCounters lockCounters = getGlobalLockCounters(lockPath);
lockCounters.lockReleaseErrorCount.incrementAndGet();
removeLastLockAttempt(lockCounters, LockAttempt::releasedWithError);
}
/** Mutable method (see class doc) */
public void startRecording(String recordId) {
ongoingRecording = Optional.of(RecordedLockAttempts.startRecording(recordId));
}
/** Mutable method (see class doc) */
public void stopRecording() {
if (ongoingRecording.isPresent()) {
RecordedLockAttempts recording = ongoingRecording.get();
ongoingRecording = Optional.empty();
// We'll keep the recordings with the longest durations.
recording.stopRecording();
LockStats.getGlobal().reportNewStoppedRecording(recording);
}
}
private LockCounters getGlobalLockCounters(String lockPath) {
return LockStats.getGlobal().getLockCounters(lockPath);
}
private void removeLastLockAttempt(LockCounters lockCounters, Consumer<LockAttempt> completeLockAttempt) {
lockCounters.inCriticalRegionCount.decrementAndGet();
if (lockAttemptsStack.isEmpty()) {
lockCounters.noLocksErrorCount.incrementAndGet();
return;
}
LockAttempt lockAttempt = lockAttemptsStack.pollLast();
completeLockAttempt.accept(lockAttempt);
LockStats.getGlobal().maybeSample(lockAttempt);
}
}
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