co.codewizards.cloudstore.core.repo.transport

Enum FileWriteStrategy

java.lang.Object

java.lang.Enum<FileWriteStrategy>

co.codewizards.cloudstore.core.repo.transport.FileWriteStrategy

All Implemented Interfaces:

Serializable, Comparable<FileWriteStrategy>

public enum FileWriteStrategy
extends Enum<FileWriteStrategy>

Strategy controlling how and when a destination file is written.

This is merely a setting in the Config. The actual implementation is in the FileRepoTransport.

Author:

Marco หงุ่ยตระกูล-Schulze - marco at codewizards dot co

Enum Constant Summary

Enum Constants

Enum Constant and Description
directAfterTransfer Write directly into the destination file after all blocks have been transferred.
directDuringTransfer Write each block directly into the destination file immediately when it was transferred.
replaceAfterTransfer Similar to directAfterTransfer, but write a new file and then switch the files (delete the old file and rename the new file).

Field Summary

Fields

Modifier and Type	Field and Description
static FileWriteStrategy	CONFIG_DEFAULT_VALUE The defaultValue used with Config.getPropertyAsEnum(String, Enum).
static String	CONFIG_KEY The key used with Config.getPropertyAsEnum(String, Enum).

Method Summary

Methods

Modifier and Type	Method and Description
static FileWriteStrategy	valueOf(String name) Returns the enum constant of this type with the specified name.
static FileWriteStrategy[]	values() Returns an array containing the constants of this enum type, in the order they are declared.

Methods inherited from class java.lang.Enum

clone, compareTo, equals, finalize, getDeclaringClass, hashCode, name, ordinal, toString, valueOf

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Enum Constant Detail

directAfterTransfer

public static final FileWriteStrategy directAfterTransfer

Write directly into the destination file after all blocks have been transferred. During transfer, the destination file is not touched.

This strategy requires as much temporary space in the destination file system as blocks are transferred: The maximum total space requirement is thus twice the file size (old file + all blocks).

directDuringTransfer

public static final FileWriteStrategy directDuringTransfer

Write each block directly into the destination file immediately when it was transferred. Don't wait for all other blocks.

In contrast to directAfterTransfer this may leave the destination file in an inconsistent state for hours or even days - as long as the transfer takes.

However, this strategy requires the least space in the file system: Only once the file size. There are no temporary files involved and thus no additional temporary space required.

replaceAfterTransfer

public static final FileWriteStrategy replaceAfterTransfer

Similar to directAfterTransfer, but write a new file and then switch the files (delete the old file and rename the new file).

This strategy is the safest concerning consistency, but requires the most temporary space in the destination file system: The maximum total space requirement is a bit more than twice the file size (old file + blocks not yet written to new file + partial new file). Because the blocks are immediately deleted when written to the (partial) new file and the new file is growing while blocks are deleted (it doesn't have the final size immediately), the required space is not 3 times the size, but - as said - only a bit more than twice the size.

Field Detail

CONFIG_KEY

public static final String CONFIG_KEY

The key used with Config.getPropertyAsEnum(String, Enum).

See Also:

Constant Field Values

CONFIG_DEFAULT_VALUE

public static final FileWriteStrategy CONFIG_DEFAULT_VALUE

The defaultValue used with Config.getPropertyAsEnum(String, Enum).

Method Detail

values

public static FileWriteStrategy[] values()

Returns an array containing the constants of this enum type, in the order they are declared. This method may be used to iterate over the constants as follows:

for (FileWriteStrategy c : FileWriteStrategy.values())
    System.out.println(c);

Returns:

an array containing the constants of this enum type, in the order they are declared

valueOf

public static FileWriteStrategy valueOf(String name)

Returns the enum constant of this type with the specified name. The string must match exactly an identifier used to declare an enum constant in this type. (Extraneous whitespace characters are not permitted.)

Parameters:

name - the name of the enum constant to be returned.

Returns:

the enum constant with the specified name

Throws:

IllegalArgumentException - if this enum type has no constant with the specified name

NullPointerException - if the argument is null