ARTEMIS-1294 Reverted TimedBuffer timeout policy
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@ -18,7 +18,6 @@ package org.apache.activemq.artemis.core.io.buffer;
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import java.nio.ByteBuffer;
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import java.util.ArrayList;
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import java.util.Collections;
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import java.util.List;
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import java.util.Timer;
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import java.util.TimerTask;
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@ -37,6 +36,9 @@ import org.apache.activemq.artemis.journal.ActiveMQJournalLogger;
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public final class TimedBuffer {
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// Constants -----------------------------------------------------
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// The number of tries on sleep before switching to spin
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private static final int MAX_CHECKS_ON_SLEEP = 20;
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// Attributes ----------------------------------------------------
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private TimedBufferObserver bufferObserver;
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@ -46,7 +48,7 @@ public final class TimedBuffer {
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// prevent that
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private final Semaphore spinLimiter = new Semaphore(1);
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private CheckTimer timerRunnable = new CheckTimer();
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private CheckTimer timerRunnable = null;
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private final int bufferSize;
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@ -58,7 +60,8 @@ public final class TimedBuffer {
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private final int timeout;
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private final AtomicLong pendingSyncs = new AtomicLong();
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// used to measure sync requests. When a sync is requested, it shouldn't take more than timeout to happen
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private volatile boolean pendingSync = false;
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private Thread timerThread;
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@ -73,7 +76,7 @@ public final class TimedBuffer {
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private final boolean logRates;
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private long bytesFlushed = 0;
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private final AtomicLong bytesFlushed = new AtomicLong(0);
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private final AtomicLong flushesDone = new AtomicLong(0);
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@ -81,6 +84,9 @@ public final class TimedBuffer {
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private TimerTask logRatesTimerTask;
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//used only in the timerThread do not synchronization
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private boolean useSleep = true;
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// no need to be volatile as every access is synchronized
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private boolean spinning = false;
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@ -99,16 +105,18 @@ public final class TimedBuffer {
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logRatesTimer = new Timer(true);
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}
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// Setting the interval for nano-sleeps
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//prefer off heap buffer to allow further humongous allocations and reduce GC overhead
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//NOTE: it is used ByteBuffer::allocateDirect instead of Unpooled::directBuffer, because the latter could allocate
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//direct ByteBuffers with no Cleaner!
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buffer = new ChannelBufferWrapper(Unpooled.wrappedBuffer(ByteBuffer.allocateDirect(size)));
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buffer.clear();
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bufferLimit = 0;
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callbacks = null;
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callbacks = new ArrayList<>();
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this.timeout = timeout;
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}
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@ -232,14 +240,11 @@ public final class TimedBuffer {
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buffer.setBytes(writerIndex, bytes, bytes.readerIndex(), readableBytes);
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buffer.writerIndex(writerIndex + readableBytes);
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if (callbacks == null) {
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callbacks = new ArrayList<>();
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}
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callbacks.add(callback);
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if (sync) {
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final long currentPendingSyncs = pendingSyncs.get();
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pendingSyncs.lazySet(currentPendingSyncs + 1);
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pendingSync = true;
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startSpin();
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}
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}
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@ -253,14 +258,11 @@ public final class TimedBuffer {
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bytes.encode(buffer);
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if (callbacks == null) {
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callbacks = new ArrayList<>();
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}
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callbacks.add(callback);
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if (sync) {
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final long currentPendingSyncs = pendingSyncs.get();
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pendingSyncs.lazySet(currentPendingSyncs + 1);
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pendingSync = true;
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startSpin();
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}
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@ -274,14 +276,18 @@ public final class TimedBuffer {
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* force means the Journal is moving to a new file. Any pending write need to be done immediately
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* or data could be lost
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*/
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private void flush(final boolean force) {
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public void flush(final boolean force) {
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synchronized (this) {
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if (!started) {
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throw new IllegalStateException("TimedBuffer is not started");
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}
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if ((force || !delayFlush) && buffer.writerIndex() > 0) {
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final int pos = buffer.writerIndex();
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int pos = buffer.writerIndex();
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if (logRates) {
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bytesFlushed.addAndGet(pos);
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}
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final ByteBuffer bufferToFlush = bufferObserver.newBuffer(bufferSize, pos);
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//bufferObserver::newBuffer doesn't necessary return a buffer with limit == pos or limit == bufferSize!!
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@ -289,33 +295,24 @@ public final class TimedBuffer {
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//perform memcpy under the hood due to the off heap buffer
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buffer.getBytes(0, bufferToFlush);
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final List<IOCallback> ioCallbacks = callbacks == null ? Collections.emptyList() : callbacks;
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bufferObserver.flushBuffer(bufferToFlush, pendingSyncs.get() > 0, ioCallbacks);
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bufferObserver.flushBuffer(bufferToFlush, pendingSync, callbacks);
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stopSpin();
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pendingSyncs.lazySet(0);
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pendingSync = false;
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callbacks = null;
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// swap the instance as the previous callback list is being used asynchronously
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callbacks = new ArrayList<>();
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buffer.clear();
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bufferLimit = 0;
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if (logRates) {
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logFlushed(pos);
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flushesDone.incrementAndGet();
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}
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}
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}
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}
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private void logFlushed(int bytes) {
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this.bytesFlushed += bytes;
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//more lightweight than XADD if single writer
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final long currentFlushesDone = flushesDone.get();
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//flushesDone::lazySet write-Release bytesFlushed
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flushesDone.lazySet(currentFlushesDone + 1L);
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}
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// Package protected ---------------------------------------------
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@ -340,21 +337,21 @@ public final class TimedBuffer {
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if (!closed) {
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long now = System.currentTimeMillis();
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final long flushesDone = TimedBuffer.this.flushesDone.get();
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//flushesDone::get read-Acquire bytesFlushed
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final long bytesFlushed = TimedBuffer.this.bytesFlushed;
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long bytesF = bytesFlushed.get();
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long flushesD = flushesDone.get();
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if (lastExecution != 0) {
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final double rate = 1000 * (double) (bytesFlushed - lastBytesFlushed) / (now - lastExecution);
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double rate = 1000 * (double) (bytesF - lastBytesFlushed) / (now - lastExecution);
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ActiveMQJournalLogger.LOGGER.writeRate(rate, (long) (rate / (1024 * 1024)));
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final double flushRate = 1000 * (double) (flushesDone - lastFlushesDone) / (now - lastExecution);
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double flushRate = 1000 * (double) (flushesD - lastFlushesDone) / (now - lastExecution);
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ActiveMQJournalLogger.LOGGER.flushRate(flushRate);
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}
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lastExecution = now;
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lastBytesFlushed = bytesFlushed;
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lastBytesFlushed = bytesF;
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lastFlushesDone = flushesDone;
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lastFlushesDone = flushesD;
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}
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}
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@ -370,40 +367,74 @@ public final class TimedBuffer {
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private volatile boolean closed = false;
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int checks = 0;
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int failedChecks = 0;
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long timeBefore = 0;
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@Override
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public void run() {
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int waitTimes = 0;
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long lastFlushTime = 0;
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long estimatedOptimalBatch = Runtime.getRuntime().availableProcessors();
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final Semaphore spinLimiter = TimedBuffer.this.spinLimiter;
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final long timeout = TimedBuffer.this.timeout;
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while (!closed) {
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boolean flushed = false;
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final long currentPendingSyncs = pendingSyncs.get();
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// We flush on the timer if there are pending syncs there and we've waited at least one
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// timeout since the time of the last flush.
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// Effectively flushing "resets" the timer
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// On the timeout verification, notice that we ignore the timeout check if we are using sleep
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if (currentPendingSyncs > 0) {
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if (bufferObserver != null) {
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final boolean checkpoint = System.nanoTime() > lastFlushTime + timeout;
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if (checkpoint || currentPendingSyncs >= estimatedOptimalBatch) {
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if (pendingSync) {
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if (useSleep) {
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// if using sleep, we will always flush
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flush();
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if (checkpoint) {
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estimatedOptimalBatch = currentPendingSyncs;
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} else {
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estimatedOptimalBatch = Math.max(estimatedOptimalBatch, currentPendingSyncs);
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}
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lastFlushTime = System.nanoTime();
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//a flush has been requested
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flushed = true;
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} else if (bufferObserver != null && System.nanoTime() > lastFlushTime + timeout) {
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// if not using flush we will spin and do the time checks manually
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flush();
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lastFlushTime = System.nanoTime();
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}
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}
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sleepIfPossible();
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try {
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spinLimiter.acquire();
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Thread.yield();
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spinLimiter.release();
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} catch (InterruptedException e) {
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throw new ActiveMQInterruptedException(e);
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}
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}
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}
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if (flushed) {
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waitTimes = 0;
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} else {
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//instead of interruptible sleeping, perform progressive parks depending on the load
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waitTimes = TimedBuffer.wait(waitTimes, spinLimiter);
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/**
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* We will attempt to use sleep only if the system supports nano-sleep
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* we will on that case verify up to MAX_CHECKS if nano sleep is behaving well.
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* if more than 50% of the checks have failed we will cancel the sleep and just use regular spin
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*/
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private void sleepIfPossible() {
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if (useSleep) {
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if (checks < MAX_CHECKS_ON_SLEEP) {
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timeBefore = System.nanoTime();
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}
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LockSupport.parkNanos(timeout);
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if (checks < MAX_CHECKS_ON_SLEEP) {
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long realTimeSleep = System.nanoTime() - timeBefore;
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// I'm letting the real time to be up to 50% than the requested sleep.
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if (realTimeSleep > timeout * 1.5) {
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failedChecks++;
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}
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if (++checks >= MAX_CHECKS_ON_SLEEP) {
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if (failedChecks > MAX_CHECKS_ON_SLEEP * 0.5) {
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ActiveMQJournalLogger.LOGGER.debug("Thread.sleep with nano seconds is not working as expected, Your kernel possibly doesn't support real time. the Journal TimedBuffer will spin for timeouts");
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useSleep = false;
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}
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}
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}
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}
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}
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@ -413,35 +444,6 @@ public final class TimedBuffer {
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}
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}
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private static int wait(int waitTimes, Semaphore spinLimiter) {
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if (waitTimes < 10) {
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//doesn't make sense to spin loop here, because of the lock around flush/addBytes operations!
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Thread.yield();
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waitTimes++;
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} else if (waitTimes < 20) {
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LockSupport.parkNanos(1L);
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waitTimes++;
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} else if (waitTimes < 50) {
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LockSupport.parkNanos(10L);
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waitTimes++;
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} else if (waitTimes < 100) {
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LockSupport.parkNanos(100L);
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waitTimes++;
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} else if (waitTimes < 1000) {
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LockSupport.parkNanos(1000L);
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waitTimes++;
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} else {
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LockSupport.parkNanos(100_000L);
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try {
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spinLimiter.acquire();
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spinLimiter.release();
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} catch (InterruptedException e) {
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throw new ActiveMQInterruptedException(e);
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}
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}
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return waitTimes;
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}
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/**
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* Sub classes (tests basically) can use this to override disabling spinning
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*/
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