Author: chetanm
Date: Wed Dec 23 09:12:18 2015
New Revision: 1721509
URL: http://svn.apache.org/viewvc?rev=1721509&view=rev
Log:
OAK-3823 - Expose the count maintained by various stats
Use of count posed a problem with Meters which get reset each second i.e.
counter used is reset in TimeSeries part. For this we would need to maintain
our own counters. Given that Meter is used in very time sensitive operation
like reads introducing a new AtomicLong might impact performance. For now
making bast effort by using a primitive Long. With JDK8 LongAdder would be a
better option
Modified:
jackrabbit/oak/trunk/oak-core/src/main/java/org/apache/jackrabbit/oak/stats/SimpleStats.java
jackrabbit/oak/trunk/oak-core/src/test/java/org/apache/jackrabbit/oak/stats/SimpleStatsTest.java
Modified:
jackrabbit/oak/trunk/oak-core/src/main/java/org/apache/jackrabbit/oak/stats/SimpleStats.java
URL:
http://svn.apache.org/viewvc/jackrabbit/oak/trunk/oak-core/src/main/java/org/apache/jackrabbit/oak/stats/SimpleStats.java?rev=1721509&r1=1721508&r2=1721509&view=diff
==============================================================================
---
jackrabbit/oak/trunk/oak-core/src/main/java/org/apache/jackrabbit/oak/stats/SimpleStats.java
(original)
+++
jackrabbit/oak/trunk/oak-core/src/main/java/org/apache/jackrabbit/oak/stats/SimpleStats.java
Wed Dec 23 09:12:18 2015
@@ -25,7 +25,22 @@ import java.util.concurrent.atomic.Atomi
public final class SimpleStats implements TimerStats, MeterStats,
CounterStats, HistogramStats {
public enum Type {COUNTER, METER, TIMER, HISTOGRAM}
private final AtomicLong statsHolder;
- private final AtomicLong counter = new AtomicLong();
+ private long counter;
+
+ /*
+ Using 2 different variables for managing the sum in meter calls
+ 1. Primitive variant is used for just increment
+ 2. AtomicLong variant is used for increment by 'n'
+
+ This is done to ensure that more frequent mark() is fast (used for
Session reads)
+ and overhead of AtomicLong is used only for less critical flows
+
+ Once we move to JDK 8 we can probably use LongAdder from that has
lesser
+ impact on performance
+ */
+ private long meterSum;
+ private final AtomicLong meterSumRef = new AtomicLong();
+
private final Type type;
public SimpleStats(AtomicLong statsHolder, Type type) {
@@ -40,12 +55,15 @@ public final class SimpleStats implement
case TIMER:
//For timer and histogram we need to manage explicit
//invocation count
- return counter.get();
- default :
- //For meter and counter the statsHolder value is
- //same as count
+ return counter;
+ case COUNTER:
return statsHolder.get();
+ case METER:
+ //For Meter it can happen that backing statsHolder gets
+ //reset each second. So need to manage that sum separately
+ return meterSum + meterSumRef.get();
}
+ throw new IllegalStateException();
}
@Override
@@ -71,16 +89,18 @@ public final class SimpleStats implement
@Override
public void mark() {
inc();
+ meterSum++;
}
@Override
public void mark(long n) {
+ meterSumRef.getAndAdd(n);
statsHolder.getAndAdd(n);
}
@Override
public void update(long duration, TimeUnit unit) {
- counter.incrementAndGet();
+ counter++;
statsHolder.getAndAdd(unit.toMillis(duration));
}
@@ -91,7 +111,7 @@ public final class SimpleStats implement
@Override
public void update(long value) {
- counter.incrementAndGet();
+ counter++;
statsHolder.getAndAdd(value);
}
Modified:
jackrabbit/oak/trunk/oak-core/src/test/java/org/apache/jackrabbit/oak/stats/SimpleStatsTest.java
URL:
http://svn.apache.org/viewvc/jackrabbit/oak/trunk/oak-core/src/test/java/org/apache/jackrabbit/oak/stats/SimpleStatsTest.java?rev=1721509&r1=1721508&r2=1721509&view=diff
==============================================================================
---
jackrabbit/oak/trunk/oak-core/src/test/java/org/apache/jackrabbit/oak/stats/SimpleStatsTest.java
(original)
+++
jackrabbit/oak/trunk/oak-core/src/test/java/org/apache/jackrabbit/oak/stats/SimpleStatsTest.java
Wed Dec 23 09:12:18 2015
@@ -110,7 +110,26 @@ public class SimpleStatsTest {
assertNotNull(ts.getValuePerSecond());
assertNotNull(ts.getValuePerWeek());
assertEquals(0, ts.getMissingValue());
+ }
+
+ @Test
+ public void meterResetAndCount() throws Exception{
+ AtomicLong counter = new AtomicLong();
+ MeterStats stats = new SimpleStats(counter, SimpleStats.Type.METER);
+
+ stats.mark();
+ assertEquals(1, stats.getCount());
+
+ stats.mark();
+ assertEquals(2, stats.getCount());
+
+ stats.mark(5);
+ assertEquals(7, stats.getCount());
+
+ counter.set(0);
+ assertEquals(7, stats.getCount());
}
+
}
