com.couchbase.lite.support.action

Class Action

java.lang.Object

com.couchbase.lite.support.action.Action

All Implemented Interfaces:

AtomicAction

public class Action
extends java.lang.Object
implements AtomicAction

An AtomicAction implementation to provide an ability to perform actions, back them out if there is an error, and clean up.

Constructor Summary

Constructors

Constructor and Description
Action()
Action(ActionBlock perform, ActionBlock backout, ActionBlock cleanup)

Method Summary

Modifier and Type	Method and Description
void	add(ActionBlock perform, ActionBlock backoutOrCleanup) Adds an action as a step of this one.
void	add(ActionBlock perform, ActionBlock backout, ActionBlock cleanup) Adds an action as a step of this one.
void	add(AtomicAction action) Adds an action as a step of thid one.
void	backout() Backs out the completed action.
void	cleanup() Cleans up after all actions have completed.
static Action	deleteFile(java.lang.String path, java.lang.String tempDir) Deletes the file/directory at the given path, if it exists.
int	getFailedStep()
java.lang.Exception	getLastError()
static Action	moveAndReplaceFile(java.lang.String srcPath, java.lang.String destPath, java.lang.String tempDir) Moves the file/directory to a new location, replacing anything that already exists there.
static Action	moveFileToEmptyPath(java.lang.String srcPath, java.lang.String destPath) Moves the file/directory to a new location, which must not already exist.
void	perform() Performs the action.
void	run() Performs all the actions in order.

Methods inherited from class java.lang.Object

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

Constructor Detail

Action

public Action()

Action

public Action(ActionBlock perform,
              ActionBlock backout,
              ActionBlock cleanup)

Method Detail

getLastError

public java.lang.Exception getLastError()

Returns:

Last exception occurred

getFailedStep

public int getFailedStep()

Returns:

Last failure step

add

public void add(AtomicAction action)

Adds an action as a step of thid one.

Parameters:

action -

add

public void add(ActionBlock perform,
                ActionBlock backout,
                ActionBlock cleanup)

Adds an action as a step of this one. The action has three components, each optional.

Parameters:

perform - A block that tries to perform the action, or returns an error if it fails. (If the block fails, it should clean up; the backOut will _not_ be called!)

backout - A block that undoes the effect of the action; it will be called if a _later_ action fails, so that the system can be returned to the initial state.

cleanup - A block that performs any necessary cleanup after all actions have been performed (e.g. deleting a temporary file.)

add

public void add(ActionBlock perform,
                ActionBlock backoutOrCleanup)

Adds an action as a step of this one. The action has two components (backout and cleanup are the same action), each optional.

Parameters:

perform - A block that tries to perform the action, or returns an error if it fails. (If the block fails, it should clean up; the backOut will _not_ be called!)

backoutOrCleanup - A block that can be both backout and cleanup block.A backout block.

run

public void run()
         throws ActionException

Performs all the actions in order. If any action fails, backs out the previously performed actions in reverse order. If the actions succeeded, cleans them up in reverse order. The `lastError` property is set to the exception thrown by the failed perform block. The `failedStep` property is set to the index of the failed perform block.

Throws:

ActionException

perform

public void perform()
             throws ActionException

Description copied from interface: AtomicAction

Performs the action. Behavior should be all-or-nothing: if the action doesn't succeed, it should restore any temporary state to what it was before, before throwing an exception.

Specified by:

perform in interface AtomicAction

Throws:

ActionException

backout

public void backout()
             throws ActionException

Description copied from interface: AtomicAction

Backs out the completed action. This will be called if a subsequent action has failed.

Specified by:

backout in interface AtomicAction

Throws:

ActionException

cleanup

public void cleanup()
             throws ActionException

Description copied from interface: AtomicAction

Cleans up after all actions have completed. This may involve releasing/deleting any temporary resources being kept around to fulfil a backOut request.

Specified by:

cleanup in interface AtomicAction

Throws:

ActionException

deleteFile

public static Action deleteFile(java.lang.String path,
                                java.lang.String tempDir)

Deletes the file/directory at the given path, if it exists.

Parameters:

path - Path to the file or directory to be deleted

tempDir - Path to a tem directory used for backing out the deleted file

Returns:

A delete file Action

moveFileToEmptyPath

public static Action moveFileToEmptyPath(java.lang.String srcPath,
                                         java.lang.String destPath)

Moves the file/directory to a new location, which must not already exist.

Parameters:

srcPath - Source path

destPath - Destination path which must not exist

Returns:

A moveFileToEmptyPath action

moveAndReplaceFile

public static Action moveAndReplaceFile(java.lang.String srcPath,
                                        java.lang.String destPath,
                                        java.lang.String tempDir)

Moves the file/directory to a new location, replacing anything that already exists there.

Parameters:

srcPath - Source path

destPath - Destination path to be replaced

tempDir - Path to a temp directory used for backing out file deletion

Returns:

A moveAndReplaceFile action