TestInputSampler.java 文件源码

/**
 * Verify IntervalSampler in mapred.lib.InputSampler, which is added back
 * for binary compatibility of M/R 1.x
 */
@Test (timeout = 30000)
@SuppressWarnings("unchecked") // IntWritable comparator not typesafe
public void testMapredIntervalSampler() throws Exception {
  final int TOT_SPLITS = 16;
  final int PER_SPLIT_SAMPLE = 4;
  final int NUM_SAMPLES = TOT_SPLITS * PER_SPLIT_SAMPLE;
  final double FREQ = 1.0 / TOT_SPLITS;
  org.apache.hadoop.mapred.lib.InputSampler.Sampler<IntWritable,NullWritable>
      sampler = new org.apache.hadoop.mapred.lib.InputSampler.IntervalSampler
          <IntWritable,NullWritable>(FREQ, NUM_SAMPLES);
  int inits[] = new int[TOT_SPLITS];
  for (int i = 0; i < TOT_SPLITS; ++i) {
    inits[i] = i;
  }
  Job ignored = Job.getInstance();
  Object[] samples = sampler.getSample(new TestInputSamplerIF(
        NUM_SAMPLES, TOT_SPLITS, inits), ignored);
  assertEquals(NUM_SAMPLES, samples.length);
  Arrays.sort(samples, new IntWritable.Comparator());
  for (int i = 0; i < NUM_SAMPLES; ++i) {
    assertEquals(i,
        ((IntWritable)samples[i]).get());
  }
}