CheckAndMutate uses timestamps inconsistently

Steps to reproduce

  @Test
  void testCantReadMyOwnWrites() throws IOException {
    Table table = // TODO
    byte[] row = Bytes.toBytes(System.currentTimeMillis());
    byte[] q = Bytes.toBytes("q");
    byte[] f = Bytes.toBytes("f");
    byte[] A = Bytes.toBytes("aaa");
    byte[] B = Bytes.toBytes("bbb");

    boolean success = table
        .checkAndMutate(row, f).qualifier(q).ifNotExists()
        .thenPut(new Put(row).addColumn(f, q, A));
    assertThat(success).isTrue();
    table.put(new Put(row).addColumn(f, q, B));
    byte[] value = table.get(new Get(row)).getValue(f, q);
    assertThat(value).isEqualTo(B); // 👈  this fails
  }

This (generally) works when setting a breakpoint on table.put(new Put(row).addColumn(f, q, B)); - i.e. slowing down the operation with the breakpoint seems to “fix” it.

[aditanase]

@kolea2 excellent feedback, thank you for the additional testing!

[kolea2]

Hi @aditanase - the Put call in HBase without a timestamp passed in will use the existing timestamp, see https://github.com/apache/hbase/blob/master/hbase-client/src/main/java/org/apache/hadoop/hbase/client/Put.java#L179, so I do not believe that will not work as is, as the existing timestamp will end up being the server side timestamp. I believe calling setTimestamp first will work. Here’s what I tried:

Example using setTimestamp last with custom timestamp:

Timestamp timestamp = new Timestamp(11111111);
            Put put = new Put(row)
                    .addColumn(f, q, A)
                    .addColumn(f, q2, B)
                    .setTimestamp(timestamp.getTime());
            boolean success = table
                    .checkAndMutate(row, f).qualifier(q).ifNotExists()
                    .thenPut(put);
            Assert.assertTrue(success);

Output (via cbt tool). Custom timestamp ignored:

xZ?6
  cf:q                                     @ 2021/03/22-13:07:13.094000
    "aaa"
  cf:q2                                    @ 2021/03/22-13:07:13.094000
    "bbb"

Example using custom timestamp first:

Timestamp timestamp = new Timestamp(11111111);
            Put put = new Put(row)
                    .setTimestamp(timestamp.getTime())
                    .addColumn(f, q, A)
                    .addColumn(f, q2, B);
            boolean success = table
                    .checkAndMutate(row, f).qualifier(q).ifNotExists()
                    .thenPut(put);
            Assert.assertTrue(success);

Output:

xZ?2
  cf:q                                     @ 1969/12/31-22:05:11.111000
    "aaa"
  cf:q2                                    @ 1969/12/31-22:05:11.111000
    "bbb"

Hope that helps!