Package org.syncany.plugins.transfer.features

Class ReadAfterWriteConsistentFeatureTransferManager

java.lang.Object

org.syncany.plugins.transfer.features.ReadAfterWriteConsistentFeatureTransferManager

All Implemented Interfaces:

FeatureTransferManager, TransferManager

public class ReadAfterWriteConsistentFeatureTransferManager
extends java.lang.Object
implements FeatureTransferManager

The ReadWriteConsistentFeatureTransferManager waits specific amount of time after upload(File, RemoteFile) and move(RemoteFile, RemoteFile) operations because some storage backends do no guarantee that a file immediately exists after creation.

It throttles existence check using a simple exponential method:
throttle(n) = 3 ^ n * 100 ms, with n being the current iteration

Constructor Summary

Constructors

Constructor	Description
ReadAfterWriteConsistentFeatureTransferManager(TransferManager originalTransferManager, TransferManager underlyingTransferManager, Config config, ReadAfterWriteConsistent readAfterWriteConsistentAnnotation)

Method Summary

Modifier and Type	Method	Description
void	connect()	Establish a connection with the remote storage.
boolean	delete(RemoteFile remoteFile)	Deletes an existing file from the remote storage permanently.
void	disconnect()	Disconnect from the remote storage.
void	download(RemoteFile remoteFile, java.io.File localFile)	Download an existing remote file to the local disk.
java.lang.String	getRemoteFilePath(java.lang.Class<? extends RemoteFile> remoteFileClass)	Return the path for a concrete RemoteFile implementation as it is stored on the remote side *
void	init(boolean createIfRequired)	Initialize remote storage.
<T extends RemoteFile> java.util.Map<java.lang.String,T>	list(java.lang.Class<T> remoteFileClass)	Retrieves a list of all files in the remote repository, filtered by the type of the desired file, i.e.
void	move(RemoteFile sourceFile, RemoteFile targetFile)	Moves an existing file in the online storage.
StorageTestResult	test(boolean testCreateTarget)	Tests whether the repository parameters are valid.
boolean	testRepoFileExists()	Tests whether the repository file exists (see SyncanyRemoteFile).
boolean	testTargetCanCreate()	Tests whether the target path/folder can be created (if it does not exist already).
boolean	testTargetCanWrite()	Tests whether the target path/folder is writable by the application.
boolean	testTargetExists()	Tests whether the target path/folder exists.
void	upload(java.io.File localFile, RemoteFile remoteFile)	Update an existing local file to the online storage.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ReadAfterWriteConsistentFeatureTransferManager

public ReadAfterWriteConsistentFeatureTransferManager(TransferManager originalTransferManager,
                                                      TransferManager underlyingTransferManager,
                                                      Config config,
                                                      ReadAfterWriteConsistent readAfterWriteConsistentAnnotation)

Method Detail

connect

public void connect()
             throws StorageException

Description copied from interface: TransferManager

Establish a connection with the remote storage.

This method does not validate the correctness of the repository and it does not create any folders. The former is done by TransferManager.test(boolean), the latter is done by TransferManager.init(boolean).

Specified by:

connect in interface TransferManager

Throws:

StorageException - If the connection fails due to no Internet connection, authentication errors, etc.

disconnect

public void disconnect()
                throws StorageException

Description copied from interface: TransferManager

Disconnect from the remote storage.

Specified by:

disconnect in interface TransferManager

Throws:

StorageException - If the connection fails due to no Internet connection, authentication errors, etc.

init

public void init(boolean createIfRequired)
          throws StorageException

Description copied from interface: TransferManager

Initialize remote storage. This method is called to set up a new repository.

Specified by:

init in interface TransferManager

Parameters:

createIfRequired - true if the method should handle repo creation

Throws:

StorageException - If the connection drops, or any other exception occurs.

download

public void download(RemoteFile remoteFile,
                     java.io.File localFile)
              throws StorageException

Description copied from interface: TransferManager

Download an existing remote file to the local disk.

The file is either downloaded completely or nothing at all. In the latter case, a StorageException is thrown.

Implementations must make sure that if a file matches the specified name schema, it must be complete and consistent.

If remoteFile does not exist, a StorageFileNotFoundException is thrown.

Specified by:

download in interface TransferManager

Parameters:

remoteFile - Existing source file on the remote storage. The only required property of the remote file is the name.

localFile - Not existing local file to which the remote file is going to be downloaded.

Throws:

StorageException - If the connection fails due to no Internet connection, authentication errors, etc.

move

public void move(RemoteFile sourceFile,
                 RemoteFile targetFile)
          throws StorageException

Description copied from interface: TransferManager

Moves an existing file in the online storage.

If the sourceFile does not exists, a StorageMoveException is thrown.

Specified by:

move in interface TransferManager

Parameters:

sourceFile - Existing remote file that is to be moved.

targetFile - Destination for the remote file.

Throws:

StorageException - If the connection fails due to no Internet connection, authentication errors, etc.

upload

public void upload(java.io.File localFile,
                   RemoteFile remoteFile)
            throws StorageException

Description copied from interface: TransferManager

Update an existing local file to the online storage.

The file is either uploaded completely or nothing at all. In the latter case, a StorageException is thrown.

Implementations must make sure that if a file matches the specified name schema, it must be complete and consistent.

Implementations must NOT upload a file if it already exists and has the same file size as the local file.

Specified by:

upload in interface TransferManager

Parameters:

localFile - Existing local file that is going to be uploaded.

remoteFile - Not existing destination file on the remote storage. The only required property of the remote file is the name.

Throws:

StorageException - If the connection fails due to no Internet connection, authentication errors, etc.

delete

public boolean delete(RemoteFile remoteFile)
               throws StorageException

Description copied from interface: TransferManager

Deletes an existing file from the remote storage permanently.

In case the remote file does not exist, it returns immediately without any notice. If the file cannot be deleted or the connection breaks, a StorageException is thrown.

Specified by:

delete in interface TransferManager

Parameters:

remoteFile - Existing remote file to be deleted. The only required property of the remote file is the name.

Throws:

StorageException - If the connection fails due to no Internet connection, authentication errors, etc

list

public <T extends RemoteFile> java.util.Map<java.lang.String,T> list(java.lang.Class<T> remoteFileClass)
                                                                    throws StorageException

Description copied from interface: TransferManager

Retrieves a list of all files in the remote repository, filtered by the type of the desired file, i.e. by a sub-class of RemoteFile.

Specified by:

list in interface TransferManager

Parameters:

remoteFileClass - Filter class: RemoteFile or a sub-type thereof

Returns:

Returns a list of remote files. In the map, the key is the file name, the value the entire RemoteFile object.

Throws:

StorageException - If the connection fails due to no Internet connection, authentication errors, etc

getRemoteFilePath

public java.lang.String getRemoteFilePath(java.lang.Class<? extends RemoteFile> remoteFileClass)

Description copied from interface: TransferManager

Return the path for a concrete RemoteFile implementation as it is stored on the remote side *

Specified by:

getRemoteFilePath in interface TransferManager

Parameters:

remoteFileClass - The class to provide the path for

Returns:

A string pointing to the folder where a file is stored

test

public StorageTestResult test(boolean testCreateTarget)

Description copied from interface: TransferManager

Tests whether the repository parameters are valid. In particular, the method tests whether a target (folder, bucket, etc.) exists or, if not, whether it can be created. It furthermore tests whether a repository at the target already exists by checking if the SyncanyRemoteFile exists.

The relevant result is determined by the following methods:

• TransferManager.testTargetExists(): Tests whether the target exists.
• TransferManager.testTargetCanWrite(): Tests whether the target is writable.
• TransferManager.testTargetCanCreate(): Tests whether the target can be created if it does not exist already. This is only called if testCreateTarget is set.
• TransferManager.testRepoFileExists(): Tests whether the repo file exists.

Specified by:

test in interface TransferManager

Parameters:

testCreateTarget - If true, the test will test if the target can be created in case it does not exist. If false, this test will be skipped.

Returns:

Returns the result of testing the repository.

See Also:

StorageTestResult

testTargetExists

public boolean testTargetExists()
                         throws StorageException

Description copied from interface: TransferManager

Tests whether the target path/folder exists. This might be done by listing the parent path/folder or by retrieving metadata about the target. The method returns true if the target exists, false otherwise.

This method is called by the TransferManager.test(boolean) method (only during repository initialization or initial connection).

Specified by:

testTargetExists in interface TransferManager

Returns:

Returns true if the target exists, false otherwise

Throws:

StorageException - If the test cannot be performed, e.g. due to a connection failure

testTargetCanWrite

public boolean testTargetCanWrite()
                           throws StorageException

Description copied from interface: TransferManager

Tests whether the target path/folder is writable by the application. This method may either check the write permissions of the target or actually write a test file to check write access. If the target does not exist, false is returned. If the target exists and is writable, true is returned.

This method is called by the TransferManager.test(boolean) method (only during repository initialization or initial connection).

Specified by:

testTargetCanWrite in interface TransferManager

Returns:

Returns true if the target can be written to, false otherwise

Throws:

StorageException - If the test cannot be performed, e.g. due to a connection failure

testTargetCanCreate

public boolean testTargetCanCreate()
                            throws StorageException

Description copied from interface: TransferManager

Tests whether the target path/folder can be created (if it does not exist already). This method may either check the permissions of the parent path/folder or actually create and delete the target to determine create permissions.

If the target already exists, the method returns true. If it does not, but it can be created (according to tests of this method), it also returns true. In all other cases, false is returned.

This method is called by the TransferManager.test(boolean) method, but only if the testCreateTarget flag is set to true!

Specified by:

testTargetCanCreate in interface TransferManager

Returns:

Returns true if the target can be created or already exists, false otherwise

Throws:

StorageException - If the test cannot be performed, e.g. due to a connection failure

testRepoFileExists

public boolean testRepoFileExists()
                           throws StorageException

Description copied from interface: TransferManager

Tests whether the repository file exists (see SyncanyRemoteFile). This method is called by the TransferManager.test(boolean) method (only during repository initialization (or initial connection).

This method is called by the TransferManager.test(boolean) method (only during repository initialization or initial connection).

Specified by:

testRepoFileExists in interface TransferManager

Returns:

Returns true if the repository is valid, false otherwise

Throws:

StorageException - If the test cannot be performed, e.g. due to a connection failure