initial commit

timer/HRTimerResolution.java

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+import java.text.DecimalFormat;
+
+import com.vladium.utils.timing.ITimer;
+import com.vladium.utils.timing.TimerFactory;
+
+// ----------------------------------------------------------------------------
+/**
+ * A demo class to show off the higher resolution available from HRTimer class
+ * and to investigate the resolution offered by Java "time-related"
+ * methods other than System.currentTimeMillis().<P>
+ * 
+ * Make sure that hrtlib.dll JNI lib is in java.library.path or TimerFactory
+ * will fall back to the Java system timer:
+ * <PRE>
+ *  >java -Djava.library.path=(dir containing hrtlib.dll) HRTimerResolution
+ * </PRE>
+ * 
+ * @author (C) <a href="mailto:vroubtsov@illinoisalumni.org">Vlad Roubtsov</a>, 2002
+ */
+public class HRTimerResolution
+{
+    // public: ................................................................
+    
+    public static void main (final String [] args) throws Exception
+    {
+        final DecimalFormat format = new DecimalFormat ();
+        format.setMinimumFractionDigits (3);
+        format.setMaximumFractionDigits (3);
+        
+        // create an ITimer using the Factory class:
+        final ITimer timer = TimerFactory.newTimer ();
+        
+        // JIT/hotspot warmup:
+        for (int i = 0; i < 3000; ++ i)
+        {
+            timer.start ();
+            timer.stop ();
+            timer.getDuration ();
+            timer.reset ();
+        }
+        
+        final Object lock = new Object (); // this is used by monitor.wait() below
+        
+        for (int i = 0; i < 5; ++ i)
+        {
+            timer.start ();
+           
+            // uncomment various lines below to see the resolution
+            // offered by other Java time-related methods; with all
+            // lines commented out this loop reports time elapsed
+            // between successive calls to t.start() and t.stop(), thus
+            // providing an estimate for timer's raw resolution
+            
+            synchronized (lock) { lock.wait (1); }
+            //Thread.currentThread ().sleep (1);
+            //Thread.currentThread ().sleep (0, 500);
+            //Thread.currentThread ().join (1);
+    
+            timer.stop ();
+
+            System.out.println ("duration = "
+                + format.format (timer.getDuration ()) + " ms");            
+            timer.reset ();
+        }
+    } 
+
+} // end of class
+// ----------------------------------------------------------------------------

timer/SystemTimerResolution.java

@@ -0,0 +1,31 @@
+// ----------------------------------------------------------------------------
+/**
+ * A simple class to see what the Java system timer resolution is on your
+ * system.
+ * 
+ * @author (C) <a href="mailto:vroubtsov@illinoisalumni.org">Vlad Roubtsov</a>, 2002
+ */
+public class SystemTimerResolution
+{
+    // public: ................................................................
+    
+    public static void main (final String [] args)
+    {
+        // JIT/hotspot warmup:
+        for (int r = 0; r < 3000; ++ r) System.currentTimeMillis ();
+        
+        long time = System.currentTimeMillis (), time_prev = time;
+        
+        for (int i = 0; i < 5; ++ i)
+        {
+            // busy wait until system time changes: 
+            while (time == time_prev)
+                time = System.currentTimeMillis ();
+            
+            System.out.println ("delta = " + (time - time_prev) + " ms");
+            time_prev = time;
+        }
+    }
+
+} // end of class
+// ----------------------------------------------------------------------------

timer/com/vladium/utils/timing/ITimer.java

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+
+package com.vladium.utils.timing;
+
+// ----------------------------------------------------------------------------
+/**
+ * A simple interface for measuring time intervals. An instance of this goes
+ * through the following lifecycle states:
+ * <DL>
+ *  <DT> <EM>ready</EM>
+ *      <DD> timer is ready to start a new measurement
+ *  <DT> <EM>started</EM>
+ *      <DD> timer has recorded the starting time interval point
+ *  <DT> <EM>stopped</EM>
+ *      <DD> timer has recorded the ending time interval point
+ * </DL>
+ * See individual methods for details.<P>
+ * 
+ * If this library has been compiled with {@link ITimerConstants#DO_STATE_CHECKS}
+ * set to 'true' the implementation will enforce this lifecycle model and throw
+ * IllegalStateException when it is violated.
+ * 
+ * @author (C) <a href="mailto:vroubtsov@illinoisalumni.org">Vlad Roubtsov</a>, 2002
+ */
+public interface ITimer
+{
+    // public: ................................................................
+    
+    /**
+     * Starts a new time interval and advances this timer instance to 'started'
+     * state. This method can be called from 'ready' state only.
+     */
+    void start ();
+    
+    /**
+     * Terminates the current time interval and advances this timer instance to
+     * 'stopped' state. Interval duration will be available via
+     * {@link #getDuration()} method. This method can be called from 'started'
+     * state only. 
+     */
+    void stop ();
+    
+    /**
+     * Returns the duration of the time interval that elapsed between the last
+     * calls to {@link #start()} and {@link #stop()}. This method can be called
+     * any number of times from 'stopped' state and will return the same value
+     * each time.<P>
+     * 
+     * @return interval duration in milliseconds 
+     */
+    double getDuration ();
+    
+    /**
+     * This method can be called from any state and will reset this timer
+     * instance back to 'ready' state. 

timer/com/vladium/utils/timing/ITimerConstants.java

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+
+package com.vladium.utils.timing;
+
+// ----------------------------------------------------------------------------
+/**
+ * A package-private collection of constants used by {@link ITimer} implementations
+ * in <code>HRTimer</code> and <code>JavaSystemTimer</code> classes.
+ *
+ * @author (C) <a href="mailto:vroubtsov@illinoisalumni.org">Vlad Roubtsov</a>, 2002
+ */
+interface ITimerConstants
+{
+    // public: ................................................................
+    
+    /**
+     * Conditional compilation flag to enable/disable state checking in timer
+     * implementations. Just about the only reason you might want to disable
+     * this is to reduce the timer overhead, but in practice the gain is very
+     * small. 
+     */
+    static final boolean DO_STATE_CHECKS = true;
+    
+    /**
+     * Timer state enumeration. 
+     */
+    static final int STATE_READY = 0, STATE_STARTED = 1, STATE_STOPPED = 2;
+    
+    /**
+     * User-friendly timer state names indexed by their state values.
+     */
+    static final String [] STATE_NAMES = {"READY", "STARTED", "STOPPED"};

timer/com/vladium/utils/timing/JavaSystemTimer.java

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+
+package com.vladium.utils.timing;
+
+// ----------------------------------------------------------------------------
+/**
+ * A package-private implementation of {@link ITimer} based around Java system
+ * timer [<code>System.currentTimeMillis()</code> method]. It is used when
+ * <code>HRTimer</code> implementation is unavailable.<P> 
+ * 
+ * {@link TimerFactory} acts as the Factory for this class.<P>
+ * 
+ * MT-safety: an instance of this class is safe to be used within the same
+ * thread only.
+ * 
+ * @author (C) <a href="mailto:vroubtsov@illinoisalumni.org">Vlad Roubtsov</a>, 2002
+ */
+final class JavaSystemTimer implements ITimer, ITimerConstants 
+{
+    // public: ................................................................
+    
+    public void start ()
+    {
+        if (DO_STATE_CHECKS)
+        {
+            if (m_state != STATE_READY)
+                throw new IllegalStateException (this + ": start() must be called from READY state, current state is " + STATE_NAMES [m_state]);
+        }
+        
+        if (DO_STATE_CHECKS) m_state = STATE_STARTED;
+        m_data = System.currentTimeMillis ();
+    }
+    
+    public void stop ()
+    {
+        // latch stop time in a local var before doing anything else:
+        final long data = System.currentTimeMillis ();
+        
+        if (DO_STATE_CHECKS)
+        {
+            if (m_state != STATE_STARTED)
+                throw new IllegalStateException (this + ": stop() must be called from STARTED state, current state is " + STATE_NAMES [m_state]);
+        }
+        
+        m_data = data - m_data;
+        if (DO_STATE_CHECKS) m_state = STATE_STOPPED;
+    }
+    
+    public double getDuration ()
+    {
+        if (DO_STATE_CHECKS)
+        {
+            if (m_state != STATE_STOPPED)
+                throw new IllegalStateException (this + ": getDuration() must be called from STOPPED state, current state is " + STATE_NAMES [m_state]);
+        }
+        
+        return m_data;
+    }
+    
+    public void reset ()
+    {
+        if (DO_STATE_CHECKS) m_state = STATE_READY;
+    }
+    
+    // protected: .............................................................
+
+    // package: ...............................................................
+        
+    // private: ...............................................................
+    
+    private int m_state; // used to keep track of timer state
+    private long m_data; // timing data
+
+} // end of class
+// ----------------------------------------------------------------------------

timer/com/vladium/utils/timing/TimerFactory.java

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+
+package com.vladium.utils.timing;
+
+// ----------------------------------------------------------------------------
+/**
+ * This non-instantiable non-extendible class acts as a Factory for {@link ITimer}
+ * implementations.
+ * 
+ * @author (C) <a href="mailto:vroubtsov@illinoisalumni.org">Vlad Roubtsov</a>, 2002
+ */
+public abstract class TimerFactory
+{
+    // public: ................................................................
+
+	private static final String HRTIMER_LIB = "hrtlib";
+
+    /**
+     * Creates a new instance of {@link ITimer} which is returned in 'ready'
+     * state. If the JNI-based/high-resolution implementation is not available
+     * this will return an instance of <code>JavaSystemTimer</code>, so this
+     * method is guaranteed not to fail.
+     * 
+     * @return ITimer a new timer instance in 'ready' state [never null] 
+     */
+	
+	public static void initialize(String path) {
+
+		UnsatisfiedLinkError exception = null;
+		
+		try {
+			System.loadLibrary (HRTIMER_LIB);
+		} catch (UnsatisfiedLinkError e) {
+			if(path != null) {
+				try {
+					System.load(path);
+				} catch (UnsatisfiedLinkError ex) {
+					exception = ex;
+				}
+			} else {
+				exception = e;
+			}
+		}
+
+		if(exception != null) {
+			System.out.println ("native lib '" + HRTIMER_LIB
+					+ "' not found in 'java.library.path': "
+					+ System.getProperty ("java.library.path")
+					+path==null?"":(" or in "+path));
+
+			throw exception; // re-throw
+		}
+	}
+	
+    public static ITimer newTimer ()
+    {
+//        try
+//        {
+            return new HRTimer ();
+//        }
+//        catch (Throwable t)
+//        {
+//            return new JavaSystemTimer ();
+//        }
+    }
+    
+    // protected: .............................................................
+
+    // package: ...............................................................
+    
+    // private: ...............................................................
+    
+    private TimerFactory () {} // prevent subclassing
+    
+} // end of class

timer/native/com_vladium_utils_timing_HRTimer.c

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+/* ------------------------------------------------------------------------- */
+/*
+ * A win32 implementation of JNI methods in com.vladium.utils.timing.HRTimer
+ * class. The author compiled it using Microsoft Visual C++ but the code
+ * should be easy to use with any compiler for win32 platform.
+ *
+ * For simplicity, this implementaion assumes JNI 1.2+ and omits error handling.
+ *
+ * (C) 2002, Vladimir Roubtsov [vroubtsov@illinoisalumni.org]
+ */
+/* ------------------------------------------------------------------------- */
+
+#if !defined NDEBUG
+#include <stdio.h>
+#endif // NDEBUG
+
+#include <windows.h>
+
+#include "com_vladium_utils_timing_HRTimer.h"
+
+// scale factor for converting a performancce counter reading into milliseconds:
+static jdouble s_scaleFactor;
+
+/* ------------------------------------------------------------------------- */
+
+/*
+ * This method was added in JNI 1.2. It is executed once before any other
+ * methods are called and is ostensibly for negotiating JNI spec versions, but
+ * can also be conveniently used for initializing variables that will not
+ * change throughout the lifetime of this process.
+ */
+JNIEXPORT jint JNICALL
+JNI_OnLoad (JavaVM * vm, void * reserved)
+{
+    LARGE_INTEGER counterFrequency;
+
+    QueryPerformanceFrequency (& counterFrequency);
+
+    // NOTE: counterFrequency will be zero for a machine that does not have
+    // support for a high-resolution counter. This is only likely for very
+    // old hardware but for a robust implementation you should handle this
+    // case.
+
+#if !defined NDEBUG
+    printf ("PCFrequency called: %I64d\n", counterFrequency.QuadPart);
+#endif
+
+    s_scaleFactor = counterFrequency.QuadPart / 1000.0;
+
+
+    return JNI_VERSION_1_2;
+}
+/* ......................................................................... */
+
+/*
+ * Class:     com_vladium_utils_timing_HRTimer
+ * Method:    getTime
+ * Signature: ()D
+ */
+JNIEXPORT jdouble JNICALL
+Java_com_vladium_utils_timing_HRTimer_getTime (JNIEnv * e, jclass cls)
+{
+    LARGE_INTEGER counterReading;
+
+    QueryPerformanceCounter (& counterReading);
+
+    return counterReading.QuadPart / s_scaleFactor;
+}
+
+/* ------------------------------------------------------------------------- */
+/* end of file */

timer/native/com_vladium_utils_timing_HRTimer.h

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+/* DO NOT EDIT THIS FILE - it is machine generated */
+#include <jni.h>
+/* Header for class com_vladium_utils_timing_HRTimer */
+
+#ifndef _Included_com_vladium_utils_timing_HRTimer
+#define _Included_com_vladium_utils_timing_HRTimer
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/*
+ * Class:     com_vladium_utils_timing_HRTimer
+ * Method:    getTime
+ * Signature: ()D
+ */
+JNIEXPORT jdouble JNICALL
+Java_com_vladium_utils_timing_HRTimer_getTime (JNIEnv *, jclass);
+
+#ifdef __cplusplus
+}
+#endif
+#endif