net.openhft.chronicle.queue.internal.util

Class InternalFileUtil

java.lang.Object

net.openhft.chronicle.queue.internal.util.InternalFileUtil

public final class InternalFileUtil
extends Object

Utility methods for handling Files in connection with ChronicleQueue.

Since:

5.17.34

Author:

Per Minborg

Method Summary

Modifier and Type	Method and Description
static boolean	hasQueueSuffix(@NotNull File file) Returns if the provided file has the Chronicle Queue file suffix.
static @NotNull Stream<File>	removableRollFileCandidates(@NotNull File baseDir) Returns a Stream of roll Queue files that are likely removable from the given baseDir without affecting any Queue process that is currently active in the given baseDir reading data sequentially.
static FileState	state(@NotNull File file) Returns if the given file is used by any process (i.e.

Methods inherited from class java.lang.Object

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

Method Detail

removableRollFileCandidates

@NotNull
public static @NotNull Stream<File> removableRollFileCandidates(@NotNull
                                                                         @NotNull File baseDir)

Returns a Stream of roll Queue files that are likely removable from the given baseDir without affecting any Queue process that is currently active in the given baseDir reading data sequentially.

Files are returned in order of creation and can successively be removed in that order. If the removal of a particular file fails, then subsequent files must be untouched.

WARNING: This method is inherently un-deterministic as new Queue processes may join or leave at any time asynchronously. Thus, it is not recommended to store results produced by this method for longer periods.

Only sequential reading is supported because random access Tailers can read at any location at any time.

Here is an example of how unused files can be removed:

     for (File file : removableFileCandidates(baseDir).collect(Collectors.toList())) {
         if (!file.delete()) {
             break;
         }
     }
 

Parameters:

baseDir - containing queue file removal candidates

Returns:

a Stream of roll Queue files that are likely removable from the given baseDir without affecting any Queue process that is currently active in the given baseDir reading data sequentially

Throws:

UnsupportedOperationException - if this operation is not supported for the current platform (e.g. Windows).

hasQueueSuffix

public static boolean hasQueueSuffix(@NotNull
                                     @NotNull File file)

Returns if the provided file has the Chronicle Queue file suffix. The current file suffix is ".cq4".

Parameters:

file - to check

Returns:

if the provided file has the ChronicleQueue file suffix

state

public static FileState state(@NotNull
                              @NotNull File file)

Returns if the given file is used by any process (i.e. has the file open for reading or writing).

If the open state of the given file can not be determined, true is returned.

Parameters:

file - to check

Returns:

if the given file is used by any process

Throws:

UnsupportedOperationException - if this operation is not supported for the current platform (e.g. Windows).