private void startChecksum(ByteBuffer dataBuffer, boolean isChecksumTarget)
throws ChecksumException {
if (!doChecksumOnRead) {
return;
}
if (!isChecksumTarget) {
return;
}
/* Clear out any previous data. */
cksumValidator.reset();
int originalPosition = threadSafeBufferPosition(dataBuffer);
if (currentEntryHeader.isInvisible()) {
/*
* Turn off invisibility so that the checksum will succeed. When
* entries are made invisible, the checksum is not adjusted. Note
* that the dataBuffer can leave the invisible bit transformed,
* because the header has already been initialized, and this data
* will never be read again.
*/
LogEntryHeader.turnOffInvisible(
dataBuffer, originalPosition - LogEntryHeader.MIN_HEADER_SIZE);
}
/* Position the buffer at the start of the data, after the checksum. */
int headerSizeMinusChecksum = currentEntryHeader.getInvariantSizeMinusChecksum();
int entryTypeStart = originalPosition - headerSizeMinusChecksum;
threadSafeBufferPosition(dataBuffer, entryTypeStart);
/* Load the validate with the header bytes. */
cksumValidator.update(dataBuffer, headerSizeMinusChecksum);
/* Move the data buffer back to the original position. */
threadSafeBufferPosition(dataBuffer, originalPosition);
}
