org.apache.camel.component.file
Interface GenericFileExclusiveReadLockStrategy<T>

All Known Implementing Classes:

FileChangedExclusiveReadLockStrategy, FileLockExclusiveReadLockStrategy, FileRenameExclusiveReadLockStrategy, GenericFileRenameExclusiveReadLockStrategy, MarkerFileExclusiveReadLockStrategy

public interface GenericFileExclusiveReadLockStrategy<T>

Strategy for acquiring exclusive read locks for files to be consumed. After granting the read lock it is released, we just want to make sure that when we start consuming the file its not currently in progress of being written by third party.

Camel supports out of the box the following strategies:

• FileRenameExclusiveReadLockStrategy waiting until its possible to rename the file.
• FileLockExclusiveReadLockStrategy acquiring a RW file lock for the duration of the processing.
• MarkerFileExclusiveReadLockStrategy using a marker file for acquiring read lock.
• FileChangedExclusiveReadLockStrategy using a file changed detection for acquiring read lock.

Method Summary

boolean	acquireExclusiveReadLock(GenericFileOperations<T> operations, GenericFile<T> file, Exchange exchange) Acquires exclusive read lock to the file.
void	prepareOnStartup(GenericFileOperations<T> operations, GenericFileEndpoint<T> endpoint) Allows custom logic to be run on startup preparing the strategy, such as removing old lock files etc.
void	releaseExclusiveReadLock(GenericFileOperations<T> operations, GenericFile<T> file, Exchange exchange) Releases the exclusive read lock granted by the acquireExclusiveReadLock method.
void	setCheckInterval(long checkInterval) Sets the check interval period.
void	setTimeout(long timeout) Sets an optional timeout period.

Method Detail

prepareOnStartup

void prepareOnStartup(GenericFileOperations<T> operations,
                      GenericFileEndpoint<T> endpoint)
                      throws Exception

Allows custom logic to be run on startup preparing the strategy, such as removing old lock files etc.

Parameters:

operations - generic file operations

endpoint - the endpoint

Throws:

Exception - can be thrown in case of errors

acquireExclusiveReadLock

boolean acquireExclusiveReadLock(GenericFileOperations<T> operations,
                                 GenericFile<T> file,
                                 Exchange exchange)
                                 throws Exception

Acquires exclusive read lock to the file.

Parameters:

operations - generic file operations

file - the file

exchange - the exchange

Returns:

true if read lock was acquired. If false Camel will skip the file and try it on the next poll

Throws:

Exception - can be thrown in case of errors

releaseExclusiveReadLock

void releaseExclusiveReadLock(GenericFileOperations<T> operations,
                              GenericFile<T> file,
                              Exchange exchange)
                              throws Exception

Releases the exclusive read lock granted by the acquireExclusiveReadLock method.

Parameters:

operations - generic file operations

file - the file

exchange - the exchange

Throws:

Exception - can be thrown in case of errors

setTimeout

void setTimeout(long timeout)

Sets an optional timeout period.

If the readlock could not be granted within the time period then the wait is stopped and the acquireExclusiveReadLock method returns false.

Parameters:

timeout - period in millis

setCheckInterval

void setCheckInterval(long checkInterval)

Sets the check interval period.

The check interval is used for sleeping between attempts to acquire read lock. Setting a high value allows to cater for slow writes in case the producer of the file is slow.

The default period is 1000 millis.

Parameters:

checkInterval - interval in millis