public boolean acquireExclusiveReadLock(
GenericFileOperations<FTPFile> operations, GenericFile<FTPFile> file, Exchange exchange)
throws Exception {
boolean exclusive = false;
LOG.trace("Waiting for exclusive read lock to file: " + file);
long lastModified = Long.MIN_VALUE;
long length = Long.MIN_VALUE;
StopWatch watch = new StopWatch();
long startTime = (new Date()).getTime();
while (!exclusive) {
// timeout check
if (timeout > 0) {
long delta = watch.taken();
if (delta > timeout) {
CamelLogger.log(
LOG,
readLockLoggingLevel,
"Cannot acquire read lock within "
+ timeout
+ " millis. Will skip the file: "
+ file);
// we could not get the lock within the timeout period, so return false
return false;
}
}
long newLastModified = 0;
long newLength = 0;
List<FTPFile> files;
if (fastExistsCheck) {
// use the absolute file path to only pickup the file we want to check, this avoids
// expensive
// list operations if we have a lot of files in the directory
LOG.trace("Using fast exists to update file information for {}", file);
files = operations.listFiles(file.getAbsoluteFilePath());
} else {
LOG.trace(
"Using full directory listing to update file information for {}. Consider enabling fastExistsCheck option.",
file);
// fast option not enabled, so list the directory and filter the file name
files = operations.listFiles(file.getParent());
}
LOG.trace("List files {} found {} files", file.getAbsoluteFilePath(), files.size());
for (FTPFile f : files) {
if (f.getName().equals(file.getFileNameOnly())) {
newLength = f.getSize();
if (f.getTimestamp() != null) {
newLastModified = f.getTimestamp().getTimeInMillis();
}
}
}
LOG.trace(
"Previous last modified: " + lastModified + ", new last modified: " + newLastModified);
LOG.trace("Previous length: " + length + ", new length: " + newLength);
long newOlderThan = startTime + watch.taken() - minAge;
LOG.trace("New older than threshold: {}", newOlderThan);
if (newLength >= minLength
&& ((minAge == 0 && newLastModified == lastModified && newLength == length)
|| (minAge != 0 && newLastModified < newOlderThan))) {
LOG.trace("Read lock acquired.");
exclusive = true;
} else {
// set new base file change information
lastModified = newLastModified;
length = newLength;
boolean interrupted = sleep();
if (interrupted) {
// we were interrupted while sleeping, we are likely being shutdown so return false
return false;
}
}
}
return exclusive;
}
