69 lines
2.1 KiB
Java
69 lines
2.1 KiB
Java
// Copyright (C) 2015 The Android Open Source Project
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package com.google.gerrit.metrics.dropwizard;
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import com.google.common.collect.ImmutableSet;
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import java.util.concurrent.TimeUnit;
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import java.util.concurrent.atomic.AtomicLong;
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/**
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* Run a user specified trigger only once every 2 seconds.
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*
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* <p>This allows the same Runnable trigger to be applied to several metrics. When a recorder is
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* sampling the related metrics only the first access will perform recomputation. Reading other
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* related metrics will rely on the already set values for the next several seconds.
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*/
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class CallbackGroup implements Runnable {
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private static final long PERIOD = TimeUnit.SECONDS.toNanos(2);
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private final AtomicLong reloadAt;
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private final Runnable trigger;
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private final ImmutableSet<CallbackMetricGlue> metrics;
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private final Object reloadLock = new Object();
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CallbackGroup(Runnable trigger, ImmutableSet<CallbackMetricGlue> metrics) {
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this.reloadAt = new AtomicLong(0);
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this.trigger = trigger;
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this.metrics = metrics;
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}
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@Override
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public void run() {
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if (reload()) {
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synchronized (reloadLock) {
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for (CallbackMetricGlue m : metrics) {
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m.beginSet();
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}
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trigger.run();
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for (CallbackMetricGlue m : metrics) {
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m.endSet();
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}
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}
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}
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}
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private boolean reload() {
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for (; ; ) {
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long now = System.nanoTime();
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long next = reloadAt.get();
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if (next > now) {
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return false;
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} else if (reloadAt.compareAndSet(next, now + PERIOD)) {
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return true;
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}
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}
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}
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}
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