KAFKA-8570: Grow buffer to hold down converted records if it was insufficiently sized

[dhruvilshah3]

Backport #6974 to 1.1

When the log contains out of order message formats (for example v2 message followed by v1 message) and consists of compressed batches typically greater than 1kB in size, it is possible for down-conversion to fail. With compressed batches, we estimate the size of down-converted batches using:

    private static int estimateCompressedSizeInBytes(int size, CompressionType compressionType) {
        return compressionType == CompressionType.NONE ? size : Math.min(Math.max(size / 2, 1024), 1 << 16);
    }

This almost always underestimates size of down-converted records if the batch is between 1kB-64kB in size. In general, this means we may under estimate the total size required for compressed batches.

Because of an implicit assumption in the code that messages with a lower message format appear before any with a higher message format, we do not grow the buffer we copy the down converted records into when we see a message <= the target message format. This assumption becomes incorrect when the log contains out of order message formats, for example because of leaders flapping while upgrading the message format.

[hachikuji]

retest this please

[hachikuji]

retest this please

[dhruvilshah3]

Thanks for looking @hachikuji. Looks like we have 2 green builds. The test failure in the JDK 7 build seems unrelated to the changes - I ran the test locally to verify.

[hachikuji]

Thanks for the backport!