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);
}
/**
* Add the provided record at the end of this log.
*
* <p>The record must have a key strictly higher than the key of the last record added. If it is
* not the case, the record is not appended and the method returns immediately.
*
* <p>In order to ensure that record is written out of buffers and persisted to file system, it is
* necessary to explicitely call the {@code syncToFileSystem()} method.
*
* @param record The record to add.
* @throws ChangelogException If an error occurs while adding the record to the log.
*/
public void append(final Record<K, V> record) throws ChangelogException {
// If this exclusive lock happens to be a bottleneck :
// 1. use a shared lock for appending the record first
// 2. switch to an exclusive lock only if rotation is needed
// See http://sources.forgerock.org/cru/CR-3548#c27521 for full detail
exclusiveLock.lock();
try {
if (isClosed) {
return;
}
if (recordIsBreakingKeyOrdering(record)) {
logger.info(
LocalizableMessage.raw(
"Rejecting append to log '%s' for record: [%s], last key appended: [%s]",
logPath.getPath(), record, lastAppendedKey != null ? lastAppendedKey : "null"));
return;
}
LogFile<K, V> headLogFile = getHeadLogFile();
if (mustRotate(headLogFile)) {
logger.trace(
INFO_CHANGELOG_LOG_FILE_ROTATION.get(logPath.getPath(), headLogFile.getSizeInBytes()));
rotateHeadLogFile();
headLogFile = getHeadLogFile();
}
headLogFile.append(record);
lastAppendedKey = record.getKey();
} finally {
exclusiveLock.unlock();
}
}
/**
* Find the highest key that corresponds to a record that is the oldest (or first) of a read-only
* log file and where value mapped from the record is lower or equals to provided limit value.
*
* <p>Example<br>
* Given a log with 3 log files, with Record<Int, String> and Mapper<String, Long> mapping a
* string to its long value
*
* <ul>
* <li>1_10.log where oldest record is (key=1, value="50")
* <li>11_20.log where oldest record is (key=11, value="150")
* <li>head.log where oldest record is (key=25, value="250")
* </ul>
*
* Then
*
* <ul>
* <li>findBoundaryKeyFromRecord(mapper, 20) => null
* <li>findBoundaryKeyFromRecord(mapper, 50) => 1
* <li>findBoundaryKeyFromRecord(mapper, 100) => 1
* <li>findBoundaryKeyFromRecord(mapper, 150) => 11
* <li>findBoundaryKeyFromRecord(mapper, 200) => 11
* <li>findBoundaryKeyFromRecord(mapper, 250) => 25
* <li>findBoundaryKeyFromRecord(mapper, 300) => 25
* </ul>
*
* @param <V2> Type of the value extracted from the record
* @param mapper The mapper to extract a value from a record. It is expected that extracted values
* are ordered according to an order consistent with this log ordering, i.e. for two records,
* if key(R1) > key(R2) then extractedValue(R1) > extractedValue(R2).
* @param limitValue The limit value to search for
* @return the key or {@code null} if no key corresponds
* @throws ChangelogException If a problem occurs
*/
<V2 extends Comparable<V2>> K findBoundaryKeyFromRecord(
Record.Mapper<V, V2> mapper, V2 limitValue) throws ChangelogException {
sharedLock.lock();
try {
K key = null;
for (LogFile<K, V> logFile : logFiles.values()) {
final Record<K, V> record = logFile.getOldestRecord();
final V2 oldestValue = mapper.map(record.getValue());
if (oldestValue.compareTo(limitValue) > 0) {
return key;
}
key = record.getKey();
}
return key;
} finally {
sharedLock.unlock();
}
}
/** Indicates if the provided record has a key that would break the key ordering in the log. */
private boolean recordIsBreakingKeyOrdering(final Record<K, V> record) {
return lastAppendedKey != null && record.getKey().compareTo(lastAppendedKey) <= 0;
}