private void unlock() {
if (lock != null) {
try {
lock.release();
} catch (IOException e) {
log.error("Error releasing lock", e);
}
}
if (lock_fc != null) {
try {
lock_fc.close();
} catch (IOException e) {
log.error("Error closing file channel", e);
}
}
if (lock_raf != null) {
try {
lock_raf.close();
} catch (IOException e) {
log.error("Error closing file", e);
}
}
lock = null;
lock_raf = null;
lock_fc = null;
}
@CheckForNull
public synchronized byte[] get(@Nonnull String obj, @Nullable Callable<byte[]> valueLoader)
throws Exception {
String key = getKey(obj);
try {
lock();
if (!forceUpdate) {
byte[] cached = getCache(key);
if (cached != null) {
log.debug("cache hit for " + obj + " -> " + key);
return cached;
}
log.debug("cache miss for " + obj + " -> " + key);
} else {
log.debug("cache force update for " + obj + " -> " + key);
}
if (valueLoader != null) {
byte[] value = valueLoader.call();
if (value != null) {
putCache(key, value);
}
return value;
}
} finally {
unlock();
}
return null;
}
/**
* Deletes cache entries that are no longer valid according to the default expiration time period.
*/
public synchronized void clean() {
log.info("cache: cleaning");
try {
lock();
deleteCacheEntries(createCleanFilter());
} catch (IOException e) {
log.error("Error cleaning cache", e);
} finally {
unlock();
}
}
public PersistentCache(
Path baseDir, long defaultDurationToExpireMs, Log log, boolean forceUpdate) {
this.baseDir = baseDir;
this.defaultDurationToExpireMs = defaultDurationToExpireMs;
this.log = log;
reconfigure(forceUpdate);
log.debug("cache: " + baseDir + ", default expiration time (ms): " + defaultDurationToExpireMs);
}
private void deleteCacheEntries(DirectoryStream.Filter<Path> filter) throws IOException {
try (DirectoryStream<Path> stream = Files.newDirectoryStream(baseDir, filter)) {
for (Path p : stream) {
try {
Files.delete(p);
} catch (Exception e) {
log.error("Error deleting " + p, e);
}
}
}
}
public void reconfigure(boolean forceUpdate) {
this.forceUpdate = forceUpdate;
if (forceUpdate) {
log.debug("cache: forcing update");
}
try {
Files.createDirectories(baseDir);
} catch (IOException e) {
throw new IllegalStateException("failed to create cache dir", e);
}
}
private boolean validateCacheEntry(Path cacheEntryPath, long durationToExpireMs)
throws IOException {
if (!Files.exists(cacheEntryPath)) {
return false;
}
if (isCacheEntryExpired(cacheEntryPath, durationToExpireMs)) {
log.debug("cache: expiring entry");
Files.delete(cacheEntryPath);
return false;
}
return true;
}