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/*
* Copyright (c) 2010-2015 Pivotal Software, Inc. All rights reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License"); you
* may not use this file except in compliance with the License. You
* may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
* implied. See the License for the specific language governing
* permissions and limitations under the License. See accompanying
* LICENSE file.
*/
package com.gemstone.gemfire.internal;
import com.gemstone.gemfire.internal.cache.GemFireCacheImpl;
import com.gemstone.gemfire.internal.shared.NativeCalls;
import com.gemstone.gemfire.internal.shared.SystemProperties;
/**
* A timer class that reports current or elapsed time in nanonseconds.
* The static method {@link #getTime} reports the current time.
* The instance methods support basic
* stop-watch-style functions that are convenient for simple performance
* measurements. For example:
*
class Example {
void example() {
NanoTimer timer = new NanoTimer();
for (int i = 0; i < n; ++i) {
someComputationThatYouAreMeasuring();
long duration = timer.reset();
System.out.println("Duration: " + duration);
// To avoid contaminating timing with printing times,
// you could call reset again here.
}
long average = timer.getTimeSinceConstruction() / n;
System.out.println("Average: " + average);
}
}
*
*
* @author Darrel Schneider
* @author Kirk Lund
*/
public final class NanoTimer {
public static final long NANOS_PER_MILLISECOND = 1000000;
private static boolean isNativeTimer;
private static final NativeCalls nativeCall = NativeCalls.getInstance();
public static final int CLOCKID_BEST;
public static boolean CLOCKID_USE_SYSNANOTIME;
public final static String NATIVETIMER_TYPE_PROPERTY =
"gemfire.nativetimer.type";
public static int nativeTimerType;
static {
/*
* currently _nanoTime(..) isn't implemented in gemfire lib.
* for gemfirexd, its implemented only for Linux/Solaris as of now.
*
* TODO:SB: check for Mac linux variants.
*/
try {
isNativeTimer = GemFireCacheImpl.gfxdSystem()
&& NativeCalls.getInstance().loadNativeLibrary() ? SharedLibrary
.register("gemfirexd") : false;
// test method call. can throw UnsatisfiedLinkError if unsuccessful.
_nanoTime(NativeCalls.CLOCKID_REALTIME);
} catch (Exception e) {
isNativeTimer = false;
if (SharedLibrary.debug) {
SharedLibrary.logInitMessage(LogWriterImpl.WARNING_LEVEL,
"_nanoTime couldn't be invoked successfully.", e);
}
} catch (UnsatisfiedLinkError e) {
isNativeTimer = false;
if (SharedLibrary.debug) {
SharedLibrary.logInitMessage(LogWriterImpl.WARNING_LEVEL,
"_nanoTime couldn't be invoked successfully.", e);
}
}
int clockIdBest = NativeCalls.CLOCKID_MONOTONIC;
if (isNativeTimer) {
final NativeCalls n = NativeCalls.getInstance();
if (n != null && n.isNativeTimerEnabled()) {
final String msg = "nanoTime clock resolution: MONOTONIC="
+ n.clockResolution(NativeCalls.CLOCKID_MONOTONIC)
+ " CLOCK_PROCESS_CPUTIME_ID="
+ n.clockResolution(NativeCalls.CLOCKID_PROCESS_CPUTIME_ID)
+ " CLOCK_THREAD_CPUTIME_ID="
+ n.clockResolution(NativeCalls.CLOCKID_THREAD_CPUTIME_ID);
SharedLibrary.logInitMessage(LogWriterImpl.INFO_LEVEL, msg, null);
String testMsg = "nanoTime time taken for call+loop:";
// don't really believe clock_getres
// clockIds listed in order of preference; MONOTONIC highest
// preference since if it is proper then it is most efficient
// via System.nanoTime() itself
int[] clockIds = { NativeCalls.CLOCKID_PROCESS_CPUTIME_ID,
NativeCalls.CLOCKID_THREAD_CPUTIME_ID,
NativeCalls.CLOCKID_MONOTONIC };
// keep some warmup runs
int numRuns = 5;
while (numRuns-- > 0) {
clockIdBest = NativeCalls.CLOCKID_MONOTONIC;
for (int clockId : clockIds) {
int sum = 0;
long start = _nanoTime(clockId);
for (int i = 0; i < 10; i++) {
sum += i;
}
long end = _nanoTime(clockId);
if (numRuns == 0) {
testMsg += " CLOCKID=" + clockId + " time=" + (end - start)
+ "nanos (sum=" + sum + ')';
}
if (end > start) {
clockIdBest = clockId;
}
}
}
SharedLibrary.logInitMessage(LogWriterImpl.FINE_LEVEL, testMsg, null);
}
}
CLOCKID_BEST = clockIdBest;
setNativeTimer(true,
getNativeTimerTypeFromString(SystemProperties.getServerInstance()
.getString(NATIVETIMER_TYPE_PROPERTY, "DEFAULT")));
}
/**
* implemented in utils.c (@see com/pivotal/gemfirexd/internal/engine) & packed
* into gemfirexd native library. any change in the implementation should be
* recompiled using gfxd-rebuild-shared-library after incrementing the library
* version (gemfirexd.native.version) in the build script.
*
* @param clk_id
* enumeration constants as defined here.
*/
public static native long _nanoTime(int clk_id);
/**
* The timestamp taken when this timer was constructed.
*/
private final long constructionTime;
/**
* The timestamp taken when this timer was last reset or constructed.
*/
private long lastResetTime;
/**
* Create a NanoTimer.
*/
public NanoTimer() {
this.lastResetTime = getTime();
this.constructionTime = this.lastResetTime;
}
/**
* Converts nanoseconds to milliseconds by dividing nanos by
* {@link #NANOS_PER_MILLISECOND}.
*
* @param nanos value in nanoseconds
* @return value converted to milliseconds
*/
public static long nanosToMillis(long nanos) {
return nanos / NANOS_PER_MILLISECOND;
}
/**
* Converts milliseconds to nanoseconds by multiplying millis by
* {@link #NANOS_PER_MILLISECOND}.
*
* @param millis value in milliseconds
* @return value converted to nanoseconds
*/
public static long millisToNanos(long millis) {
return millis * NANOS_PER_MILLISECOND;
}
/**
* Return the time in nanoseconds since some arbitrary time in the past.
* The time rolls over to zero every 2^64 nanosecs (approx 584 years).
* Interval computations spanning periods longer than this will be wrong.
*/
public static long getTime() {
return java.lang.System.nanoTime();
}
/**
* Indicates whether native library will be used.
*
* @return returns whether JNI based timer is enabled.
*/
public static final boolean isJNINativeTimerEnabled() {
return isNativeTimer;
}
/**
* Check native timer using jni/jna is implemented in this platform.
*
* @return true if using o/s level system call via jni otherwise false.
* @see #isJNINativeTimerEnabled()
*/
public static final boolean isNativeTimerEnabled() {
return isNativeTimer || nativeCall.isNativeTimerEnabled();
}
/**
* Nanosecond precision performance counter using native system call. calling
* overhead is listed below for various kinds of clocks. if high precision
* counter is unsupported by the o/s or high precision clock isn't implemented
* yet, falls back to java.lang.System.nanoTime.
*
* The values for clock_id argument now reside in
* {@link NativeCalls} class.
*
* @param clock_id
*
* - CLOCK_THREAD_CPUTIME_ID
* In Linux:
* Average overhead is ~120 nanosecond irrespective of number of
* threads. This is because it provides thread work time excluding
* unscheduled wait time by the o/s (@see clock_gettime).
*
*
* - CLOCK_PROCESS_CPUTIME_ID
* In Linux:
* Average overhead varies depending on number of concurrent
* threads. For single threaded call it incurs ~5 to ~11 microsecond
*
*
*
* - CLOCK_REALTIME, CLOCK_MONOTONIC, CLOCK_MONOTONIC_RAW
* In Linux:
* Yields similar performance as o/s clock resolution offered by
* java.lang.System.nanoTime.
*
*
* @param useJNA
* if false, avoids JNA system call. if true, attempts to use jni for
* implemented platforms otherwise uses jna implementation. if
* neither is supported, returns System.nanoTime.
*
* @see #isNativeTimerEnabled()
* @return performance counter long value.
*/
public static final long nativeNanoTime(final int clock_id,
final boolean useJNA) {
return (isNativeTimer ? _nanoTime(clock_id)
: (useJNA ? NativeCalls.getInstance().nanoTime(clock_id)
: java.lang.System.nanoTime()));
}
/**
*
* This function was added because the call to {@link #nativeNanoTime(int, boolean)} with
* CLOCKID_PROCESS_CPUTIME_ID is taking few milliseconds. With this, EXPLAIN query
* scenarios are terribly slow because there can be millions of calls to nanoTime.
* java.lang.System.nanoTime() should be perfect in most of the cases because the
* timer resolution is 1 ns and timer speed is few tens of nano seconds. Making it
* as the default behavior. If {@link #NATIVETIMER_TYPE_PROPERTY} is set then
* native timer of the specified type is used.
*/
public static final long nanoTime() {
return CLOCKID_USE_SYSNANOTIME ? java.lang.System.nanoTime()
: nativeNanoTime(nativeTimerType, true);
}
/**
* Return the construction time in nanoseconds since some arbitrary time
* in the past.
*
* @return timestamp in nanoseconds since construction.
*/
public long getConstructionTime() {
return this.constructionTime;
}
/**
* Return the last reset time in naonseconds since some arbitrary time
* in the past.
*
* The time rolls over to zero every 2^64 nanosecs (approx 584 years).
* Interval computations spanning periods longer than this will be wrong.
* If the timer has not yet been reset then the construction time
* is returned.
*
* @return timestamp in nanoseconds of construction or the last reset.
*/
public long getLastResetTime() {
return this.lastResetTime;
}
/**
* Compute and return the time in nanoseconds since the last reset or
* construction of this timer, and reset the timer to the current
* {@link #getTime}.
*
* @return time in nanoseconds since construction or last reset.
*/
public long reset() {
long save = this.lastResetTime;
this.lastResetTime = getTime();
return this.lastResetTime - save;
}
/**
* Compute and return the time in nanoseconds since the last reset or
* construction of this Timer, but does not reset this timer.
*
* @return time in nanoseconds since construction or last reset.
*/
public long getTimeSinceReset() {
return getTime() - this.lastResetTime;
}
/**
* Compute and return the time in nanoseconds since this timer was
* constructed.
*
* @return time in nanoseconds since construction.
*/
public long getTimeSinceConstruction() {
return getTime() - this.constructionTime;
}
static final int getNativeTimerTypeFromString(String timerType) {
timerType = timerType.toUpperCase();
if (timerType.equals("CLOCK_REALTIME")) {
return NativeCalls.CLOCKID_REALTIME;
} else if (timerType.equals("CLOCK_MONOTONIC")) {
return NativeCalls.CLOCKID_MONOTONIC;
} else if (timerType.equals("CLOCK_PROCESS_CPUTIME_ID")) {
return NativeCalls.CLOCKID_PROCESS_CPUTIME_ID;
} else if (timerType.equals("CLOCK_THREAD_CPUTIME_ID")) {
return NativeCalls.CLOCKID_THREAD_CPUTIME_ID;
} else if (timerType.equals("CLOCK_MONOTONIC_RAW")) {
return NativeCalls.CLOCKID_MONOTONIC_RAW;
} else if (timerType.equals("DEFAULT")) {
return CLOCKID_BEST;
} else {
throw new IllegalArgumentException(
"Unknown native clockId type = " + timerType);
}
}
public static final void setNativeTimer(boolean nativeTimer,
String timerType) {
setNativeTimer(nativeTimer, getNativeTimerTypeFromString(timerType));
}
static final void setNativeTimer(boolean nativeTimer, int timerType) {
if (nativeTimer) {
nativeTimerType = timerType;
CLOCKID_USE_SYSNANOTIME = (timerType == NativeCalls.CLOCKID_MONOTONIC);
} else {
// reset to default timer type ignoring the actual argument
nativeTimerType = NativeCalls.CLOCKID_MONOTONIC;
CLOCKID_USE_SYSNANOTIME = true;
}
}
public static final boolean getIsNativeTimer() {
return nativeTimerType != NativeCalls.CLOCKID_MONOTONIC;
}
public static final String getNativeTimerType() {
switch (nativeTimerType) {
case NativeCalls.CLOCKID_REALTIME:
return "CLOCK_REALTIME";
case NativeCalls.CLOCKID_MONOTONIC:
return "CLOCK_MONOTONIC";
case NativeCalls.CLOCKID_PROCESS_CPUTIME_ID:
return "CLOCK_PROCESS_CPUTIME_ID";
case NativeCalls.CLOCKID_THREAD_CPUTIME_ID:
return "CLOCK_THREAD_CPUTIME_ID";
case NativeCalls.CLOCKID_MONOTONIC_RAW:
return "CLOCK_MONOTONIC_RAW";
default:
return "UNKNOWN";
}
}
}