HADOOP-14276. Add a nanosecond API to Time/Timer/FakeTimer. Contributed by Erik Krogen.

This commit is contained in:
Zhe Zhang 2017-04-06 16:52:22 -07:00
parent 0116c3c957
commit 95b7f1d29a
5 changed files with 52 additions and 31 deletions

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@ -76,14 +76,6 @@ public int compare(Entry left, Entry right) {
return l > r? 1: l < r? -1: 0; return l > r? 1: l < r? -1: 0;
} }
}; };
/** A clock for measuring time so that it can be mocked in unit tests. */
static class Clock {
/** @return the current time. */
long currentTime() {
return System.nanoTime();
}
}
private static int updateRecommendedLength(int recommendedLength, private static int updateRecommendedLength(int recommendedLength,
int sizeLimit) { int sizeLimit) {
@ -102,7 +94,7 @@ private static int updateRecommendedLength(int recommendedLength,
private final long creationExpirationPeriod; private final long creationExpirationPeriod;
private final long accessExpirationPeriod; private final long accessExpirationPeriod;
private final int sizeLimit; private final int sizeLimit;
private final Clock clock; private final Timer timer;
/** /**
* @param recommendedLength Recommended size of the internal array. * @param recommendedLength Recommended size of the internal array.
@ -120,7 +112,7 @@ public LightWeightCache(final int recommendedLength,
final long creationExpirationPeriod, final long creationExpirationPeriod,
final long accessExpirationPeriod) { final long accessExpirationPeriod) {
this(recommendedLength, sizeLimit, this(recommendedLength, sizeLimit,
creationExpirationPeriod, accessExpirationPeriod, new Clock()); creationExpirationPeriod, accessExpirationPeriod, new Timer());
} }
@VisibleForTesting @VisibleForTesting
@ -128,7 +120,7 @@ public LightWeightCache(final int recommendedLength,
final int sizeLimit, final int sizeLimit,
final long creationExpirationPeriod, final long creationExpirationPeriod,
final long accessExpirationPeriod, final long accessExpirationPeriod,
final Clock clock) { final Timer timer) {
super(updateRecommendedLength(recommendedLength, sizeLimit)); super(updateRecommendedLength(recommendedLength, sizeLimit));
this.sizeLimit = sizeLimit; this.sizeLimit = sizeLimit;
@ -147,11 +139,11 @@ public LightWeightCache(final int recommendedLength,
this.queue = new PriorityQueue<Entry>( this.queue = new PriorityQueue<Entry>(
sizeLimit > 0? sizeLimit + 1: 1 << 10, expirationTimeComparator); sizeLimit > 0? sizeLimit + 1: 1 << 10, expirationTimeComparator);
this.clock = clock; this.timer = timer;
} }
void setExpirationTime(final Entry e, final long expirationPeriod) { void setExpirationTime(final Entry e, final long expirationPeriod) {
e.setExpirationTime(clock.currentTime() + expirationPeriod); e.setExpirationTime(timer.monotonicNowNanos() + expirationPeriod);
} }
boolean isExpired(final Entry e, final long now) { boolean isExpired(final Entry e, final long now) {
@ -168,7 +160,7 @@ private E evict() {
/** Evict expired entries. */ /** Evict expired entries. */
private void evictExpiredEntries() { private void evictExpiredEntries() {
final long now = clock.currentTime(); final long now = timer.monotonicNowNanos();
for(int i = 0; i < EVICTION_LIMIT; i++) { for(int i = 0; i < EVICTION_LIMIT; i++) {
final Entry peeked = queue.peek(); final Entry peeked = queue.peek();
if (peeked == null || !isExpired(peeked, now)) { if (peeked == null || !isExpired(peeked, now)) {

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@ -65,6 +65,16 @@ public static long monotonicNow() {
return System.nanoTime() / NANOSECONDS_PER_MILLISECOND; return System.nanoTime() / NANOSECONDS_PER_MILLISECOND;
} }
/**
* Same as {@link #monotonicNow()} but returns its result in nanoseconds.
* Note that this is subject to the same resolution constraints as
* {@link System#nanoTime()}.
* @return a monotonic clock that counts in nanoseconds.
*/
public static long monotonicNowNanos() {
return System.nanoTime();
}
/** /**
* Convert time in millisecond to human readable format. * Convert time in millisecond to human readable format.
* @return a human readable string for the input time * @return a human readable string for the input time

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@ -48,4 +48,14 @@ public long now() {
* @return a monotonic clock that counts in milliseconds. * @return a monotonic clock that counts in milliseconds.
*/ */
public long monotonicNow() { return Time.monotonicNow(); } public long monotonicNow() { return Time.monotonicNow(); }
/**
* Same as {@link #monotonicNow()} but returns its result in nanoseconds.
* Note that this is subject to the same resolution constraints as
* {@link System#nanoTime()}.
* @return a monotonic clock that counts in nanoseconds.
*/
public long monotonicNowNanos() {
return Time.monotonicNowNanos();
}
} }

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@ -18,6 +18,7 @@
package org.apache.hadoop.util; package org.apache.hadoop.util;
import java.util.concurrent.TimeUnit;
import org.apache.hadoop.classification.InterfaceAudience; import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability; import org.apache.hadoop.classification.InterfaceStability;
@ -28,25 +29,38 @@
@InterfaceAudience.Private @InterfaceAudience.Private
@InterfaceStability.Unstable @InterfaceStability.Unstable
public class FakeTimer extends Timer { public class FakeTimer extends Timer {
private long nowMillis; private long nowNanos;
/** Constructs a FakeTimer with a non-zero value */ /** Constructs a FakeTimer with a non-zero value */
public FakeTimer() { public FakeTimer() {
nowMillis = 1000; // Initialize with a non-trivial value. nowNanos = 1000; // Initialize with a non-trivial value.
} }
@Override @Override
public long now() { public long now() {
return nowMillis; return TimeUnit.NANOSECONDS.toMillis(nowNanos);
} }
@Override @Override
public long monotonicNow() { public long monotonicNow() {
return nowMillis; return TimeUnit.NANOSECONDS.toMillis(nowNanos);
}
@Override
public long monotonicNowNanos() {
return nowNanos;
} }
/** Increases the time by milliseconds */ /** Increases the time by milliseconds */
public void advance(long advMillis) { public void advance(long advMillis) {
nowMillis += advMillis; nowNanos += TimeUnit.MILLISECONDS.toNanos(advMillis);
}
/**
* Increases the time by nanoseconds.
* @param advNanos Nanoseconds to advance by.
*/
public void advanceNanos(long advNanos) {
nowNanos += advNanos;
} }
} }

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@ -213,7 +213,7 @@ private static class LightWeightCacheTestCase implements GSet<IntEntry, IntEntry
int iterate_count = 0; int iterate_count = 0;
int contain_count = 0; int contain_count = 0;
private long currentTestTime = ran.nextInt(); private FakeTimer fakeTimer = new FakeTimer();
LightWeightCacheTestCase(int tablelength, int sizeLimit, LightWeightCacheTestCase(int tablelength, int sizeLimit,
long creationExpirationPeriod, long accessExpirationPeriod, long creationExpirationPeriod, long accessExpirationPeriod,
@ -230,12 +230,7 @@ private static class LightWeightCacheTestCase implements GSet<IntEntry, IntEntry
data = new IntData(datasize, modulus); data = new IntData(datasize, modulus);
cache = new LightWeightCache<IntEntry, IntEntry>(tablelength, sizeLimit, cache = new LightWeightCache<IntEntry, IntEntry>(tablelength, sizeLimit,
creationExpirationPeriod, 0, new LightWeightCache.Clock() { creationExpirationPeriod, 0, fakeTimer);
@Override
long currentTime() {
return currentTestTime;
}
});
Assert.assertEquals(0, cache.size()); Assert.assertEquals(0, cache.size());
} }
@ -247,7 +242,7 @@ private boolean containsTest(IntEntry key) {
} else { } else {
final IntEntry h = hashMap.remove(key); final IntEntry h = hashMap.remove(key);
if (h != null) { if (h != null) {
Assert.assertTrue(cache.isExpired(h, currentTestTime)); Assert.assertTrue(cache.isExpired(h, fakeTimer.monotonicNowNanos()));
} }
} }
return c; return c;
@ -266,7 +261,7 @@ private IntEntry getTest(IntEntry key) {
} else { } else {
final IntEntry h = hashMap.remove(key); final IntEntry h = hashMap.remove(key);
if (h != null) { if (h != null) {
Assert.assertTrue(cache.isExpired(h, currentTestTime)); Assert.assertTrue(cache.isExpired(h, fakeTimer.monotonicNowNanos()));
} }
} }
return c; return c;
@ -286,7 +281,7 @@ private IntEntry putTest(IntEntry entry) {
final IntEntry h = hashMap.put(entry); final IntEntry h = hashMap.put(entry);
if (h != null && h != entry) { if (h != null && h != entry) {
// if h == entry, its expiration time is already updated // if h == entry, its expiration time is already updated
Assert.assertTrue(cache.isExpired(h, currentTestTime)); Assert.assertTrue(cache.isExpired(h, fakeTimer.monotonicNowNanos()));
} }
} }
return c; return c;
@ -305,7 +300,7 @@ private IntEntry removeTest(IntEntry key) {
} else { } else {
final IntEntry h = hashMap.remove(key); final IntEntry h = hashMap.remove(key);
if (h != null) { if (h != null) {
Assert.assertTrue(cache.isExpired(h, currentTestTime)); Assert.assertTrue(cache.isExpired(h, fakeTimer.monotonicNowNanos()));
} }
} }
return c; return c;
@ -339,7 +334,7 @@ boolean tossCoin() {
} }
void check() { void check() {
currentTestTime += ran.nextInt() & 0x3; fakeTimer.advanceNanos(ran.nextInt() & 0x3);
//test size //test size
sizeTest(); sizeTest();