/**
* Returns the file name to use for the read-only version of the provided log file.
*
* <p>The file name is based on the lowest and highest key in the log file.
*
* @return the name to use for the read-only version of the log file
* @throws ChangelogException If an error occurs.
*/
private String generateReadOnlyFileName(final LogFile<K, V> logFile) throws ChangelogException {
final K lowestKey = logFile.getOldestRecord().getKey();
final K highestKey = logFile.getNewestRecord().getKey();
return recordParser.encodeKeyToString(lowestKey)
+ LOG_FILE_NAME_SEPARATOR
+ recordParser.encodeKeyToString(highestKey)
+ LOG_FILE_SUFFIX;
}
/**
* Returns the key bounds for the provided log file.
*
* @return the pair of (lowest key, highest key) that correspond to records stored in the
* corresponding log file.
* @throws ChangelogException if an error occurs while retrieving the keys
*/
private Pair<K, K> getKeyBounds(final LogFile<K, V> logFile) throws ChangelogException {
try {
final String name = logFile.getFile().getName();
final String[] keys =
name.substring(0, name.length() - Log.LOG_FILE_SUFFIX.length())
.split(LOG_FILE_NAME_SEPARATOR);
return Pair.of(
recordParser.decodeKeyFromString(keys[0]), recordParser.decodeKeyFromString(keys[1]));
} catch (Exception e) {
throw new ChangelogException(
ERR_CHANGELOG_UNABLE_TO_RETRIEVE_KEY_BOUNDS_FROM_FILE.get(logFile.getFile().getPath()),
e);
}
}
private void openHeadLogFile() throws ChangelogException {
final LogFile<K, V> head =
LogFile.newAppendableLogFile(new File(logPath, HEAD_LOG_FILE_NAME), recordParser);
final Record<K, V> newestRecord = head.getNewestRecord();
lastAppendedKey = newestRecord != null ? newestRecord.getKey() : null;
logFiles.put(recordParser.getMaxKey(), head);
}
/** Update the cursors that were pointing to head after a rotation of the head log file. */
private void updateOpenedCursorsOnHeadAfterRotation(
List<Pair<AbortableLogCursor<K, V>, CursorState<K, V>>> cursors) throws ChangelogException {
for (Pair<AbortableLogCursor<K, V>, CursorState<K, V>> pair : cursors) {
final CursorState<K, V> cursorState = pair.getSecond();
// Need to update the cursor only if it is pointing to the head log file
if (cursorState.isValid() && isHeadLogFile(cursorState.logFile)) {
final K previousKey = logFiles.lowerKey(recordParser.getMaxKey());
final LogFile<K, V> logFile = findLogFileFor(previousKey);
final AbortableLogCursor<K, V> cursor = pair.getFirst();
cursor.reinitializeTo(
new CursorState<K, V>(logFile, cursorState.filePosition, cursorState.record));
}
}
}