@Test
  public void testStatSampler() throws Exception {
    StatArchiveWriter.setTraceFilter("st1_1", "ST1");

    File folder = temporaryFolder.newFolder();
    String archiveFileName = folder.getAbsolutePath() + File.separator + getName() + ".gfs";

    System.setProperty("stats.disable", "false");
    System.setProperty("stats.name", getName());
    System.setProperty("stats.archive-file", archiveFileName);
    System.setProperty("stats.file-size-limit", "0");
    System.setProperty("stats.disk-space-limit", "0");
    System.setProperty("stats.sample-rate", "100");

    final CancelCriterion stopper = new CancelCriterion() {
      @Override
      public String cancelInProgress() {
        return null;
      }

      @Override
      public RuntimeException generateCancelledException(Throwable e) {
        return null;
      }
    };
    final LocalStatisticsFactory factory = new LocalStatisticsFactory(stopper);
    final StatisticDescriptor[] statsST1 =
        new StatisticDescriptor[] {factory.createDoubleCounter("double_counter_1", "d1", "u1"),
            factory.createDoubleCounter("double_counter_2", "d2", "u2", true),
            factory.createDoubleGauge("double_gauge_3", "d3", "u3"),
            factory.createDoubleGauge("double_gauge_4", "d4", "u4", false),
            factory.createIntCounter("int_counter_5", "d5", "u5"),
            factory.createIntCounter("int_counter_6", "d6", "u6", true),
            factory.createIntGauge("int_gauge_7", "d7", "u7"),
            factory.createIntGauge("int_gauge_8", "d8", "u8", false),
            factory.createLongCounter("long_counter_9", "d9", "u9"),
            factory.createLongCounter("long_counter_10", "d10", "u10", true),
            factory.createLongGauge("long_gauge_11", "d11", "u11"),
            factory.createLongGauge("long_gauge_12", "d12", "u12", false),
            factory.createLongGauge("sampled_long", "d13", "u13", false),
            factory.createIntGauge("sampled_int", "d14", "u14", false),
            factory.createDoubleGauge("sampled_double", "d15", "u15", false)};
    final StatisticsType ST1 = factory.createType("ST1", "ST1", statsST1);
    final Statistics st1_1 = factory.createAtomicStatistics(ST1, "st1_1", 1);
    st1_1.setIntSupplier("sampled_int", () -> 5);
    getOrCreateExpectedValueMap(st1_1).put("sampled_int", 5);
    st1_1.setLongSupplier("sampled_long", () -> 6);
    getOrCreateExpectedValueMap(st1_1).put("sampled_long", 6);
    st1_1.setDoubleSupplier("sampled_double", () -> 7.0);
    getOrCreateExpectedValueMap(st1_1).put("sampled_double", 7.0);

    await("awaiting StatSampler readiness")
        .until(() -> hasSamplerStatsInstances(factory));

    Statistics[] samplerStatsInstances = factory.findStatisticsByTextId("statSampler");
    assertNotNull(samplerStatsInstances);
    assertEquals(1, samplerStatsInstances.length);
    final Statistics samplerStats = samplerStatsInstances[0];

    incDouble(st1_1, "double_counter_1", 1);
    incDouble(st1_1, "double_gauge_3", 3);
    incInt(st1_1, "int_counter_5", 5);
    incInt(st1_1, "int_gauge_7", 7);
    incLong(st1_1, "long_counter_9", 9);
    incLong(st1_1, "long_gauge_11", 11);

    waitForStatSamplerToRun(samplerStats);

    incDouble(st1_1, "double_counter_1", 1);
    incDouble(st1_1, "double_counter_2", 1);
    incDouble(st1_1, "double_gauge_3", 1);
    incDouble(st1_1, "double_gauge_4", 1);
    incInt(st1_1, "int_counter_5", 1);
    incInt(st1_1, "int_counter_6", 1);

    waitForStatSamplerToRun(samplerStats);

    incDouble(st1_1, "double_counter_1", 1);
    incDouble(st1_1, "double_counter_2", 1);
    incDouble(st1_1, "double_gauge_3", 1);
    incDouble(st1_1, "double_gauge_4", 1);
    incInt(st1_1, "int_counter_5", 1);
    incInt(st1_1, "int_counter_6", 1);
    incInt(st1_1, "int_gauge_7", 1);
    incInt(st1_1, "int_gauge_8", 1);
    incLong(st1_1, "long_counter_9", 1);
    incLong(st1_1, "long_counter_10", 1);
    incLong(st1_1, "long_gauge_11", 1);
    incLong(st1_1, "long_gauge_12", 1);

    waitForStatSamplerToRun(samplerStats);

    incDouble(st1_1, "double_counter_1", 1);
    incDouble(st1_1, "double_counter_2", 1);
    incDouble(st1_1, "double_gauge_3", -1);
    incDouble(st1_1, "double_gauge_4", 1);
    incInt(st1_1, "int_counter_5", 1);
    incInt(st1_1, "int_counter_6", 1);
    incInt(st1_1, "int_gauge_7", -1);
    incInt(st1_1, "int_gauge_8", 1);
    incLong(st1_1, "long_counter_9", 1);
    incLong(st1_1, "long_counter_10", 1);
    incLong(st1_1, "long_gauge_11", -1);
    incLong(st1_1, "long_gauge_12", 1);

    waitForStatSamplerToRun(samplerStats);

    incDouble(st1_1, "double_counter_1", 1);
    incDouble(st1_1, "double_counter_2", 1);
    incDouble(st1_1, "double_gauge_3", 1);
    incDouble(st1_1, "double_gauge_4", 1);
    incInt(st1_1, "int_counter_5", 1);
    incInt(st1_1, "int_counter_6", 1);
    incInt(st1_1, "int_gauge_7", 1);
    incInt(st1_1, "int_gauge_8", 1);
    incLong(st1_1, "long_counter_9", 1);
    incLong(st1_1, "long_counter_10", 1);
    incLong(st1_1, "long_gauge_11", 1);
    incLong(st1_1, "long_gauge_12", 1);

    waitForStatSamplerToRun(samplerStats);
    waitForStatSamplerToRun(samplerStats);
    waitForStatSamplerToRun(samplerStats);

    incDouble(st1_1, "double_counter_1", 1);
    incDouble(st1_1, "double_gauge_3", 3);
    incInt(st1_1, "int_counter_5", 5);
    incInt(st1_1, "int_gauge_7", 7);
    incLong(st1_1, "long_counter_9", 9);
    incLong(st1_1, "long_gauge_11", 11);

    waitForStatSamplerToRun(samplerStats);

    incDouble(st1_1, "double_counter_1", 1);
    incDouble(st1_1, "double_counter_2", 1);
    incDouble(st1_1, "double_gauge_3", 1);
    incDouble(st1_1, "double_gauge_4", 1);
    incInt(st1_1, "int_counter_5", 1);
    incInt(st1_1, "int_counter_6", 1);

    waitForStatSamplerToRun(samplerStats);

    incDouble(st1_1, "double_counter_1", 1);
    incDouble(st1_1, "double_counter_2", 1);
    incDouble(st1_1, "double_gauge_3", 1);
    incDouble(st1_1, "double_gauge_4", 1);
    incInt(st1_1, "int_counter_5", 1);
    incInt(st1_1, "int_counter_6", 1);
    incInt(st1_1, "int_gauge_7", 1);
    incInt(st1_1, "int_gauge_8", 1);
    incLong(st1_1, "long_counter_9", 1);
    incLong(st1_1, "long_counter_10", 1);
    incLong(st1_1, "long_gauge_11", 1);
    incLong(st1_1, "long_gauge_12", 1);

    waitForStatSamplerToRun(samplerStats);

    incDouble(st1_1, "double_counter_1", 1);
    incDouble(st1_1, "double_counter_2", 1);
    incDouble(st1_1, "double_gauge_3", -1);
    incDouble(st1_1, "double_gauge_4", 1);
    incInt(st1_1, "int_counter_5", 1);
    incInt(st1_1, "int_counter_6", 1);
    incInt(st1_1, "int_gauge_7", -1);
    incInt(st1_1, "int_gauge_8", 1);
    incLong(st1_1, "long_counter_9", 1);
    incLong(st1_1, "long_counter_10", 1);
    incLong(st1_1, "long_gauge_11", -1);
    incLong(st1_1, "long_gauge_12", 1);

    waitForStatSamplerToRun(samplerStats);

    incDouble(st1_1, "double_counter_1", 1);
    incDouble(st1_1, "double_counter_2", 1);
    incDouble(st1_1, "double_gauge_3", 1);
    incDouble(st1_1, "double_gauge_4", 1);
    incInt(st1_1, "int_counter_5", 1);
    incInt(st1_1, "int_counter_6", 1);
    incInt(st1_1, "int_gauge_7", 1);
    incInt(st1_1, "int_gauge_8", 1);
    incLong(st1_1, "long_counter_9", 1);
    incLong(st1_1, "long_counter_10", 1);
    incLong(st1_1, "long_gauge_11", 1);
    incLong(st1_1, "long_gauge_12", 1);

    /*
     * After updating all stats we should wait for the stat sampler to run at least twice. The
     * first statSampler iteration may be running as the stats are being updated. The second
     * statSampler iteration
     * makes sure that all the stats we care about have been sampled and flush to the stat archive
     */
    waitForStatSamplerToRun(samplerStats, 2);

    factory.close();

    final File archiveFile = new File(System.getProperty("stats.archive-file"));
    assertTrue(archiveFile.exists());
    final StatArchiveReader reader = new StatArchiveReader(new File[] {archiveFile}, null, false);

    List resources = reader.getResourceInstList();
    for (Object resource : resources) {
      StatArchiveReader.ResourceInst ri = (StatArchiveReader.ResourceInst) resource;
      String resourceName = ri.getName();
      assertNotNull(resourceName);

      if (!resourceName.equals("st1_1")) {
        logger.info("testStatSampler skipping {}", resourceName);
        continue;
      }

      String expectedStatsType = statisticTypes.get(resourceName);
      assertNotNull(expectedStatsType);
      assertEquals(expectedStatsType, ri.getType().getName());

      Map<String, Number> expectedStatValues = allStatistics.get(resourceName);
      assertNotNull(expectedStatValues);

      StatValue[] statValues = ri.getStatValues();
      for (int i = 0; i < statValues.length; i++) {
        String statName = ri.getType().getStats()[i].getName();
        assertNotNull(statName);
        assertNotNull(expectedStatValues.get(statName));

        assertEquals(statName, statValues[i].getDescriptor().getName());

        statValues[i].setFilter(StatValue.FILTER_NONE);
        // double[] rawSnapshots = statValues[i].getRawSnapshots();
        assertEquals("Value " + i + " for " + statName + " is wrong: " + expectedStatValues,
            expectedStatValues.get(statName).doubleValue(), statValues[i].getSnapshotsMostRecent(),
            0);
      }
    }
  }
Integration tests for statistics sampling.

@since GemFire 7.0
geode-core/src/integrationTest/java/org/apache/geode/internal/statistics/StatSamplerIntegrationTest.java