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Diffstat (limited to 'M4-RCs/qpid/dotnet/Qpid.Integration.Tests/framework/clocksynch/UDPClockSynchronizer.csx')
| -rw-r--r-- | M4-RCs/qpid/dotnet/Qpid.Integration.Tests/framework/clocksynch/UDPClockSynchronizer.csx | 453 |
1 files changed, 0 insertions, 453 deletions
diff --git a/M4-RCs/qpid/dotnet/Qpid.Integration.Tests/framework/clocksynch/UDPClockSynchronizer.csx b/M4-RCs/qpid/dotnet/Qpid.Integration.Tests/framework/clocksynch/UDPClockSynchronizer.csx deleted file mode 100644 index 98b02a043b..0000000000 --- a/M4-RCs/qpid/dotnet/Qpid.Integration.Tests/framework/clocksynch/UDPClockSynchronizer.csx +++ /dev/null @@ -1,453 +0,0 @@ -/*
- *
- * Licensed to the Apache Software Foundation (ASF) under one
- * or more contributor license agreements. See the NOTICE file
- * distributed with this work for additional information
- * regarding copyright ownership. The ASF licenses this file
- * to you 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.
- *
- */
-using log4net;
-
-using uk.co.thebadgerset.junit.extensions.util.CommandLineParser;
-using uk.co.thebadgerset.junit.extensions.util.ParsedProperties;
-
-using java.io.IOException;
-using java.net.*;
-using java.nio.ByteBuffer;
-using java.util.Arrays;
-
-namespace Apache.Qpid.Integration.Tests.framework.clocksynch
-{
- /// <summary>
- /// UDPClockSynchronizer is a <see cref="ClockSynchronizer"/> that sends pings as UDP datagrams, and uses the following simple
- /// algorithm to perform clock synchronization:
- ///
- /// <ol>
- /// <li>Slave initiates synchronization with a Reference clock.</li>
- /// <li>Slave stamps current local time on a "time request" message and sends to the Reference.</li>
- /// <li>Upon receipt by Reference, Reference stamps Reference-time and returns.</li>
- /// <li>Upon receipt by Slave, Slave subtracts current time from sent time and divides by two to compute latency. It
- /// subtracts current time from Reference time to determine Slave-Reference time delta and adds in the
- /// half-latency to get the correct clock delta.</li>
- /// <li>The first result is immediately used to update the clock since it will get the local clock into at least
- /// the right ballpark.</li>
- /// <li>The Slave repeats steps 2 through 4, 15 more times.</li>
- /// <li>The results of the packet receipts are accumulated and sorted in lowest-latency to highest-latency order. The
- /// median latency is determined by picking the mid-point sample from this ordered list.</li>
- /// <li>All samples outside 1 standard-deviation from the median are discarded and the remaining samples
- /// are averaged using an arithmetic mean.</li>
- /// </ol>
- ///
- /// <p/>The use of UDP datagrams, instead of TCP based communication eliminates the hidden delays that TCP can introduce,
- /// as it can transparently re-order or re-send packets, or introduce delays as packets are naggled.
- ///
- /// <p/><table id="crc"><caption>CRC Card</caption>
- /// <tr><th> Responsibilities <th> Collaborations
- /// <tr><td> Trigger a clock synchronziation.
- /// <tr><td> Compute a clock delta to apply to the local clock.
- /// <tr><td> Estimate the error in the synchronzation.
- /// </table>
- /// </summary>
- public class UDPClockSynchronizer : ClockSynchronizer
- {
- /// <summary> Used for debugging. </summary>
- // private static ILog log = LogManager.GetLogger(typeof(UDPClockSynchronizer));
-
- /// <summary> Defines the timeout to use when waiting for responses to time requests. </summary>
- private static final int TIMEOUT = 50;
-
- /// <summary> The clock delta. </summary>
- private long delta = 0L;
-
- /// <summary> Holds an estimate of the clock error relative to the reference clock. </summary>
- private long epsilon = 0L;
-
- /// <summary> Holds the address of the reference clock. </summary>
- private InetAddress referenceAddress;
-
- /// <summary> Holds the socket to communicate with the reference service over. </summary>
- private DatagramSocket socket;
-
- /// <summary> Used to control the shutdown in the main test loop. </summary>
- private static bool doSynch = true;
-
- /// <summary>
- /// Creates a clock synchronizer against the specified address for the reference.
- /// </summary>
- /// <param name="address"> The address of the reference service. </param>
- public UDPClockSynchronizer(string address)
- {
- try
- {
- referenceAddress = InetAddress.getByName(address);
- }
- catch (UnknownHostException e)
- {
- throw new RuntimeException(e);
- }
- }
-
- /// <summary>
- /// The slave side should call this to compute a clock delta with the reference.
- /// </summary>
- /// <exception cref="ClockSynchFailureException"> If synchronization cannot be achieved, due to unavailability of the reference
- /// time service. </exception>
- public void synch() throws ClockSynchFailureException
- {
- try
- {
- socket = new DatagramSocket();
- socket.setSoTimeout(TIMEOUT);
-
- // Synchronize on a single ping, to get the clock into the right ball-park.
- synch(1);
-
- // Synchronize on 15 pings.
- synch(15);
-
- // And again, for greater accuracy, on 31.
- synch(31);
-
- socket.close();
- }
- catch (SocketException e)
- {
- throw new RuntimeException(e);
- }
- }
-
- /// <summary>
- /// Updates the synchronization delta by performing the specified number of reference clock requests.
- /// </summary>
- /// <param name="n"> The number of reference clock request cycles to perform. </param>
- ///
- /// <exception cref="ClockSynchFailureException"> If synchronization cannot be achieved, due to unavailability of the reference
- /// time service. </exception>
- protected void synch(int n) throws ClockSynchFailureException
- {
- // log.debug("protected void synch(int n = " + n + "): called");
-
- // Create an array of deltas by performing n reference pings.
- long[] delta = new long[n];
-
- for (int i = 0; i < n; i++)
- {
- delta[i] = ping();
- }
-
- // Reject any deltas that are larger than 1 s.d. above the median.
- long median = median(delta);
- long sd = standardDeviation(delta);
-
- // log.debug("median = " + median);
- // log.debug("sd = " + sd);
-
- long[] tempDeltas = new long[n];
- int count = 0;
-
- for (int i = 0; i < n; i++)
- {
- if ((delta[i] <= (median + sd)) && (delta[i] >= (median - sd)))
- {
- tempDeltas[count] = delta[i];
- count++;
- }
- else
- {
- // log.debug("Rejected: " + delta[i]);
- }
- }
-
- System.arraycopy(tempDeltas, 0, delta, 0, count);
-
- // Estimate the delta as the mean of the remaining deltas.
- this.delta += mean(delta);
-
- // Estimate the error as the standard deviation of the remaining deltas.
- this.epsilon = standardDeviation(delta);
-
- // log.debug("this.delta = " + this.delta);
- // log.debug("this.epsilon = " + this.epsilon);
- }
-
- /// <summary>
- /// Performs a single reference clock request cycle and returns the estimated delta relative to the local clock.
- /// This is computed as the half-latency of the requst cycle, plus the reference clock, minus the local clock.
- /// </summary>
- /// <return> The estimated clock delta. </return>
- ///
- /// <exception cref="ClockSynchFailureException"> If the reference service is not responding. </exception>
- protected long ping() throws ClockSynchFailureException
- {
- // log.debug("protected long ping(): called");
-
- try
- {
- byte[] buf = new byte[256];
-
- bool timedOut = false;
- long start = 0L;
- long refTime = 0L;
- long localTime = 0L;
- long latency = 0L;
- int failCount = 0;
-
- // Keep trying the ping until it gets a response, or 10 tries in a row all time out.
- do
- {
- // Start timing the request latency.
- start = nanoTime();
-
- // Get the reference time.
- DatagramPacket packet =
- new DatagramPacket(buf, buf.length, referenceAddress, UDPClockReference.REFERENCE_PORT);
- socket.send(packet);
- packet = new DatagramPacket(buf, buf.length);
-
- timedOut = false;
-
- try
- {
- socket.receive(packet);
- }
- catch (SocketTimeoutException e)
- {
- timedOut = true;
- failCount++;
-
- continue;
- }
-
- ByteBuffer bbuf = ByteBuffer.wrap(packet.getData());
- refTime = bbuf.getLong();
-
- // Stop timing the request latency.
- localTime = nanoTime();
- latency = localTime - start;
-
- // log.debug("refTime = " + refTime);
- // log.debug("localTime = " + localTime);
- // log.debug("start = " + start);
- // log.debug("latency = " + latency);
- // log.debug("delta = " + ((latency / 2) + (refTime - localTime)));
-
- }
- while (timedOut && (failCount < 10));
-
- // Fail completely if the fail count is too high.
- if (failCount >= 10)
- {
- throw new ClockSynchFailureException("Clock reference not responding.", null);
- }
-
- // Estimate delta as (ref clock + half-latency) - local clock.
- return (latency / 2) + (refTime - localTime);
- }
- catch (IOException e)
- {
- throw new RuntimeException(e);
- }
- }
-
- /// <summary>
- /// Gets the clock delta in nano seconds.
- /// </summary>
- /// <return> The clock delta in nano seconds. </return>
- public long getDelta()
- {
- return delta;
- }
-
- /// <summary>
- /// Gets an estimate of the clock error in nan seconds.
- /// </summary>
- /// <return> An estimate of the clock error in nan seconds. </return>
- public long getEpsilon()
- {
- return epsilon;
- }
-
- /// <summary>
- /// Gets the local clock time with any computed delta added in.
- /// </summary>
- /// <return> The local clock time with any computed delta added in. </return>
- public long nanoTime()
- {
- return System.nanoTime() + delta;
- }
-
- /// <summary>
- /// Computes the median of a series of values.
- /// </summary>
- /// <param name="values"> The values. </param>
- ///
- /// <return> The median. </return>
- public static long median(long[] values)
- {
- // log.debug("public static long median(long[] values = " + Arrays.ToString(values) + "): called");
-
- long median;
-
- // Order the list of values.
- long[] orderedValues = new long[values.length];
- System.arraycopy(values, 0, orderedValues, 0, values.length);
- Arrays.sort(orderedValues);
-
- // Check if the median is computed from a pair of middle value.
- if ((orderedValues.length % 2) == 0)
- {
- int middle = orderedValues.length / 2;
-
- median = (orderedValues[middle] + orderedValues[middle - 1]) / 2;
- }
- // The median is computed from a single middle value.
- else
- {
- median = orderedValues[orderedValues.length / 2];
- }
-
- // log.debug("median = " + median);
-
- return median;
- }
-
- /// <summary>
- /// Computes the mean of a series of values.
- /// </summary>
- /// <param name="values"> The values. </param>
- ///
- /// <return> The mean. </return>
- public static long mean(long[] values)
- {
- // log.debug("public static long mean(long[] values = " + Arrays.ToString(values) + "): called");
-
- long total = 0L;
-
- for (long value : values)
- {
- total += value;
- }
-
- long mean = total / values.length;
-
- // log.debug("mean = " + mean);
-
- return mean;
- }
-
- /// <summary>
- /// Computes the variance of series of values.
- /// </summary>
- /// <param name="values"> The values. </param>
- ///
- /// <return> The variance of the values. </return>
- public static long variance(long[] values)
- {
- // log.debug("public static long variance(long[] values = " + Arrays.ToString(values) + "): called");
-
- long mean = mean(values);
-
- long totalVariance = 0;
-
- for (long value : values)
- {
- long diff = (value - mean);
- totalVariance += diff/// diff;
- }
-
- long variance = totalVariance / values.length;
-
- // log.debug("variance = " + variance);
-
- return variance;
- }
-
- /// <summary>
- /// Computes the standard deviation of a series of values.
- /// </summary>
- /// <param name="values"> The values. </param>
- ///
- /// <return> The standard deviation. </return>
- public static long standardDeviation(long[] values)
- {
- // log.debug("public static long standardDeviation(long[] values = " + Arrays.ToString(values) + "): called");
-
- long sd = Double.valueOf(Math.sqrt(variance(values))).longValue();
-
- // log.debug("sd = " + sd);
-
- return sd;
- }
-
- /// <summary>
- /// For testing purposes. Supply address of reference clock as arg 1.
- /// </summary>
- /// <param name="args"> Address of reference clock as arg 1. </param>
- public static void main(String[] args)
- {
- ParsedProperties options =
- new ParsedProperties(CommandLineParser.processCommandLine(args,
- new CommandLineParser(
- new String[][]
- {
- { "1", "Address of clock reference service.", "address", "true" }
- }), System.getProperties()));
-
- string address = options.getProperty("1");
-
- // Create a clock synchronizer.
- UDPClockSynchronizer clockSyncher = new UDPClockSynchronizer(address);
-
- // Set up a shutdown hook for it.
- Runtime.getRuntime().addShutdownHook(new Thread(new Runnable()
- {
- public void run()
- {
- doSynch = false;
- }
- }));
-
- // Repeat the clock synching until the user kills the progam.
- while (doSynch)
- {
- // Perform a clock clockSynch.
- try
- {
- clockSyncher.synch();
-
- // Print out the clock delta and estimate of the error.
- System.out.println("Delta = " + clockSyncher.getDelta());
- System.out.println("Epsilon = " + clockSyncher.getEpsilon());
-
- try
- {
- Thread.sleep(250);
- }
- catch (InterruptedException e)
- {
- // Restore the interrupted status and terminate the loop.
- Thread.currentThread().interrupt();
- doSynch = false;
- }
- }
- // Terminate if the reference time service is unavailable.
- catch (ClockSynchFailureException e)
- {
- doSynch = false;
- }
- }
- }
- }
-}
\ No newline at end of file |