[commons-rng] branch master updated: Add stress test option to combine bits with a system identity hash code.

[ah...@apache.org]

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aherbert pushed a commit to branch master
in repository https://gitbox.apache.org/repos/asf/commons-rng.git


The following commit(s) were added to refs/heads/master by this push:
     new 0bda14c  Add stress test option to combine bits with a system identity hash code.
0bda14c is described below

commit 0bda14cc5fc04155f8d1d2c4eeb8d1e1dd6160a3
Author: aherbert <ah...@apache.org>
AuthorDate: Mon Jun 3 11:38:09 2019 +0100

    Add stress test option to combine bits with a system identity hash code.
---
 .../commons/rng/examples/stress/RNGUtils.java      | 28 ++++++++++++++++++++++
 .../rng/examples/stress/StressTestCommand.java     | 16 ++++++++++++-
 2 files changed, 43 insertions(+), 1 deletion(-)

diff --git a/commons-rng-examples/examples-stress/src/main/java/org/apache/commons/rng/examples/stress/RNGUtils.java b/commons-rng-examples/examples-stress/src/main/java/org/apache/commons/rng/examples/stress/RNGUtils.java
index aac26fb..a7f77d5 100644
--- a/commons-rng-examples/examples-stress/src/main/java/org/apache/commons/rng/examples/stress/RNGUtils.java
+++ b/commons-rng-examples/examples-stress/src/main/java/org/apache/commons/rng/examples/stress/RNGUtils.java
@@ -79,6 +79,34 @@ final class RNGUtils {
     }
 
     /**
+     * Wrap the random generator with an {@link IntProvider} that will combine the bits
+     * using a {@code xor} operation with a generated hash code.
+     *
+     * <pre>{@code
+     * System.identityHashCode(new Object()) ^ rng.nextInt()
+     * }</pre>
+     *
+     * Note: This generator will be slow.
+     *
+     * @param rng The random generator.
+     * @return the hash code combined random generator.
+     * @see System#identityHashCode(Object)
+     */
+    static UniformRandomProvider createHashCodeIntProvider(final UniformRandomProvider rng) {
+        return new IntProvider() {
+            @Override
+            public int next() {
+                return System.identityHashCode(new Object()) ^ rng.nextInt();
+            }
+
+            @Override
+            public String toString() {
+                return "HashCode ^ " + rng.toString();
+            }
+        };
+    }
+
+    /**
      * Parses the argument into an object suitable for the RandomSource constructor. Supports:
      *
      * <ul>
diff --git a/commons-rng-examples/examples-stress/src/main/java/org/apache/commons/rng/examples/stress/StressTestCommand.java b/commons-rng-examples/examples-stress/src/main/java/org/apache/commons/rng/examples/stress/StressTestCommand.java
index 016d3a4..a34721e 100644
--- a/commons-rng-examples/examples-stress/src/main/java/org/apache/commons/rng/examples/stress/StressTestCommand.java
+++ b/commons-rng-examples/examples-stress/src/main/java/org/apache/commons/rng/examples/stress/StressTestCommand.java
@@ -121,13 +121,24 @@ class StressTestCommand implements Callable<Void> {
                            "Valid values: BIG_ENDIAN, LITTLE_ENDIAN."})
     private ByteOrder byteOrder = ByteOrder.nativeOrder();
 
-    /** The output byte order of the binary data. */
+    /** Flag to indicate the output should be bit-reversed. */
     @Option(names = {"-r", "--reverse-bits"},
             description = {"Reverse the bits in the data (default: ${DEFAULT-VALUE}).",
                            "Note: Generators may fail tests for a reverse sequence " +
                            "when passing using the standard sequence."})
     private boolean reverseBits;
 
+    /**
+     * Flag to indicate the output should be combined with a hashcode from a new object.
+     * This is a method used in the {@link org.apache.commons.rng.simple.internal.SeedFactory SeedFactory}.
+     *
+     * @see System#identityHashCode(Object)
+     */
+    @Option(names = {"--hashcode"},
+            description = {"Combine the bits with a hashcode (default: ${DEFAULT-VALUE}).",
+                           "System.identityHashCode(new Object()) ^ rng.nextInt()."})
+    private boolean xorHashCode;
+
     /** The flag to indicate a dry run. */
     @Option(names = {"--dry-run"},
             description = "Perform a dry run where the generators and output files are created " +
@@ -397,6 +408,9 @@ class StressTestCommand implements Callable<Void> {
             if (reverseBits) {
                 rng = RNGUtils.createReverseBitsIntProvider(rng);
             }
+            if (xorHashCode) {
+                rng = RNGUtils.createHashCodeIntProvider(rng);
+            }
             // Run the test
             final Runnable r = new StressTestTask(testData.getRandomSource(), rng, output, command,
                                                   this, progressTracker);