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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.vespa.curator.Lock;
import java.time.Duration;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentLinkedDeque;
import java.util.function.Consumer;
/**
* This class contains process-wide 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 static final ConcurrentHashMap<Thread, ThreadLockStats> locks = new ConcurrentHashMap<>();
private static final LockAttemptSamples COMPLETED_LOCK_ATTEMPT_SAMPLES = new LockAttemptSamples();
private static final ConcurrentHashMap<String, LockCounters> countersByLockPath = new ConcurrentHashMap<>();
private final Thread thread;
/** The locks are reentrant so there may be more than 1 lock for this thread. */
private final ConcurrentLinkedDeque<LockAttempt> lockAttempts = new ConcurrentLinkedDeque<>();
public static Map<String, LockCounters> getLockCountersByPath() { return Map.copyOf(countersByLockPath); }
public static List<ThreadLockStats> getThreadLockInfos() { return List.copyOf(locks.values()); }
public static List<LockAttempt> getLockInfoSamples() {
return COMPLETED_LOCK_ATTEMPT_SAMPLES.asList();
}
/** Returns the per-thread singleton ThreadLockStats. */
public static ThreadLockStats getCurrentThreadLockInfo() {
return locks.computeIfAbsent(Thread.currentThread(), ThreadLockStats::new);
}
static void clearStaticDataForTesting() {
locks.clear();
COMPLETED_LOCK_ATTEMPT_SAMPLES.clear();
countersByLockPath.clear();
}
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> getLockAttempts() { return List.copyOf(lockAttempts); }
/** Mutable method (see class doc) */
public void invokingAcquire(String lockPath, Duration timeout) {
LockCounters lockCounters = getLockCounters(lockPath);
lockCounters.invokeAcquireCount.incrementAndGet();
lockCounters.inCriticalRegionCount.incrementAndGet();
lockAttempts.addLast(LockAttempt.invokingAcquire(this, lockPath, timeout));
}
/** Mutable method (see class doc) */
public void acquireFailed(String lockPath) {
LockCounters lockCounters = getLockCounters(lockPath);
lockCounters.acquireFailedCount.incrementAndGet();
removeLastLockInfo(lockCounters, LockAttempt::acquireFailed);
}
/** Mutable method (see class doc) */
public void acquireTimedOut(String lockPath) {
LockCounters lockCounters = getLockCounters(lockPath);
if (lockAttempts.size() > 1) {
lockCounters.timeoutOnReentrancyErrorCount.incrementAndGet();
}
lockCounters.acquireTimedOutCount.incrementAndGet();
removeLastLockInfo(lockCounters, LockAttempt::timedOut);
}
/** Mutable method (see class doc) */
public void lockAcquired(String lockPath) {
getLockCounters(lockPath).lockAcquiredCount.incrementAndGet();
LockAttempt lastLockAttempt = lockAttempts.peekLast();
if (lastLockAttempt == null) {
throw new IllegalStateException("lockAcquired invoked without lockAttempts");
}
lastLockAttempt.lockAcquired();
}
/** Mutable method (see class doc) */
public void lockReleased(String lockPath) {
LockCounters lockCounters = getLockCounters(lockPath);
lockCounters.locksReleasedCount.incrementAndGet();
removeLastLockInfo(lockCounters, LockAttempt::released);
}
private LockCounters getLockCounters(String lockPath) {
return countersByLockPath.computeIfAbsent(lockPath, __ -> new LockCounters());
}
private void removeLastLockInfo(LockCounters lockCounters, Consumer<LockAttempt> completeLockInfo) {
lockCounters.inCriticalRegionCount.decrementAndGet();
if (lockAttempts.isEmpty()) {
lockCounters.noLocksErrorCount.incrementAndGet();
return;
}
LockAttempt lockAttempt = lockAttempts.pollLast();
completeLockInfo.accept(lockAttempt);
COMPLETED_LOCK_ATTEMPT_SAMPLES.maybeSample(lockAttempt);
}
}
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