How to use

convertBytesToLong

method

in

com.nike.wingtips.TraceAndSpanIdGenerator

/**
 * @return A random long pulled from the full 64-bit random search space (as opposed to the 48 bits of randomness you get from
 *          {@link java.util.Random#nextLong()}).
 */
public static long generate64BitRandomLong() {
  byte[] random8Bytes = new byte[8];
  random.nextBytes(random8Bytes);
  return convertBytesToLong(random8Bytes);
}

@Test
public void convertBytesToLong_should_work_correctly_for_known_value() {
  // given: byte[] that maps to known long value
  final long EXPECTED_LONG_VALUE = 4242424242L;
  ByteBuffer buffer = ByteBuffer.allocate(Long.SIZE / 8);
  buffer.putLong(EXPECTED_LONG_VALUE);
  byte[] longAsByteArray = buffer.array();
  assertThat(longAsByteArray.length).isEqualTo(8);
  // when: convertBytesToLong() is called
  long returnVal = TraceAndSpanIdGenerator.convertBytesToLong(longAsByteArray);
  // then: the return value is what we expect
  assertThat(returnVal).isEqualTo(EXPECTED_LONG_VALUE);
}

@Test(expected = IllegalArgumentException.class)
public void convertBytesToLong_should_explode_if_byte_array_is_less_than_8_bytes() {
  byte[] badByteArray = new byte[]{0, 0, 0, 0, 0, 0, 1};
  assertThat(badByteArray.length).isLessThan(8);
  TraceAndSpanIdGenerator.convertBytesToLong(badByteArray);
  fail("Expected IllegalArgumentException but none was thrown");
}

@Test(expected = IllegalArgumentException.class)
public void convertBytesToLong_should_explode_if_byte_array_is_more_than_8_bytes() {
  byte[] badByteArray = new byte[]{0, 0, 0, 0, 0, 0, 0, 0, 1};
  assertThat(badByteArray.length).isGreaterThan(8);
  TraceAndSpanIdGenerator.convertBytesToLong(badByteArray);
  fail("Expected IllegalArgumentException but none was thrown");
}