Package org.apache.flink.runtime.checkpoint.filemerging

Class FileMergingSnapshotManagerBase

java.lang.Object

org.apache.flink.runtime.checkpoint.filemerging.FileMergingSnapshotManagerBase

All Implemented Interfaces:

Closeable, AutoCloseable, FileMergingSnapshotManager

Direct Known Subclasses:

AcrossCheckpointFileMergingSnapshotManager, WithinCheckpointFileMergingSnapshotManager

public abstract class FileMergingSnapshotManagerBase
extends Object
implements FileMergingSnapshotManager

Base implementation of FileMergingSnapshotManager.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
protected static class	FileMergingSnapshotManagerBase.DirectoryHandleWithReferenceTrack	This class wrap DirectoryStreamStateHandle with reference count by ongoing checkpoint.

Nested classes/interfaces inherited from interface org.apache.flink.runtime.checkpoint.filemerging.FileMergingSnapshotManager

FileMergingSnapshotManager.SpaceStat, FileMergingSnapshotManager.SubtaskKey

Field Summary

Fields

Modifier and Type	Field	Description
protected org.apache.flink.core.fs.Path	checkpointDir
protected PhysicalFilePool.Type	filePoolType	Type of physical file pool.
protected org.apache.flink.core.fs.FileSystem	fs	The FileSystem that this manager works on.
protected final Executor	ioExecutor	The executor for I/O operations in this manager.
protected final Object	lock	Guard for initFileSystem(org.apache.flink.core.fs.FileSystem, org.apache.flink.core.fs.Path, org.apache.flink.core.fs.Path, org.apache.flink.core.fs.Path, int), restoreStateHandles(long, org.apache.flink.runtime.checkpoint.filemerging.FileMergingSnapshotManager.SubtaskKey, java.util.stream.Stream<org.apache.flink.runtime.state.filemerging.SegmentFileStateHandle>) and uploadedStates.
protected org.apache.flink.core.fs.Path	managedExclusiveStateDir	The private state files are merged across subtasks, there is only one directory for merged-files within one TM per job.
protected FileMergingSnapshotManagerBase.DirectoryHandleWithReferenceTrack	managedExclusiveStateDirHandle	The DirectoryStreamStateHandle with it ongoing checkpoint reference count for private state directory, one for each taskmanager and job.
protected long	maxPhysicalFileSize	Max size for a physical file.
protected final float	maxSpaceAmplification
protected FileMergingMetricGroup	metricGroup	The metric group for file merging snapshot manager.
protected PhysicalFile.PhysicalFileDeleter	physicalFileDeleter
protected org.apache.flink.core.fs.Path	sharedStateDir
protected boolean	shouldSyncAfterClosingLogicalFile	File-system dependent value.
protected FileMergingSnapshotManager.SpaceStat	spaceStat	The current space statistic, updated on file creation/deletion.
protected org.apache.flink.core.fs.Path	taskOwnedStateDir
protected TreeMap<Long,Set<LogicalFile>>	uploadedStates
protected int	writeBufferSize	The buffer size for writing files to the file system.

Constructor Summary

Constructors

Constructor	Description
FileMergingSnapshotManagerBase(String id, long maxFileSize, PhysicalFilePool.Type filePoolType, float maxSpaceAmplification, Executor ioExecutor, org.apache.flink.metrics.MetricGroup parentMetricGroup)

Method Summary

Modifier and Type	Method	Description
void	close()
boolean	couldReusePreviousStateHandle(StreamStateHandle stateHandle)	Check whether previous state handles could further be reused considering the space amplification.
FileMergingCheckpointStateOutputStream	createCheckpointStateOutputStream(FileMergingSnapshotManager.SubtaskKey subtaskKey, long checkpointId, CheckpointedStateScope scope)	Create a new FileMergingCheckpointStateOutputStream.
protected LogicalFile	createLogicalFile(PhysicalFile physicalFile, long startOffset, long length, FileMergingSnapshotManager.SubtaskKey subtaskKey)	Create a logical file on a physical file.
protected PhysicalFile	createPhysicalFile(FileMergingSnapshotManager.SubtaskKey subtaskKey, CheckpointedStateScope scope)	Create a physical file in right location (managed directory), which is specified by scope of this checkpoint and current subtask.
protected final PhysicalFilePool	createPhysicalPool()	Create physical pool by filePoolType.
protected final void	deletePhysicalFile(org.apache.flink.core.fs.Path filePath, long size)	Delete a physical file by given file path.
protected void	discardCheckpoint(long checkpointId)	The callback which will be triggered when all subtasks discarded (aborted or subsumed).
void	discardSingleLogicalFile(LogicalFile logicalFile, long checkpointId)
protected org.apache.flink.core.fs.Path	generatePhysicalFilePath(org.apache.flink.core.fs.Path dirPath)	Generate a file path for a physical file.
String	getId()
LogicalFile	getLogicalFile(LogicalFile.LogicalFileId fileId)
org.apache.flink.core.fs.Path	getManagedDir(FileMergingSnapshotManager.SubtaskKey subtaskKey, CheckpointedStateScope scope)	Get the managed directory of the file-merging snapshot manager, created in FileMergingSnapshotManager.initFileSystem(org.apache.flink.core.fs.FileSystem, org.apache.flink.core.fs.Path, org.apache.flink.core.fs.Path, org.apache.flink.core.fs.Path, int) or FileMergingSnapshotManager.registerSubtaskForSharedStates(org.apache.flink.runtime.checkpoint.filemerging.FileMergingSnapshotManager.SubtaskKey).
DirectoryStreamStateHandle	getManagedDirStateHandle(FileMergingSnapshotManager.SubtaskKey subtaskKey, CheckpointedStateScope scope)	Get the DirectoryStreamStateHandle of the managed directory, created in FileMergingSnapshotManager.initFileSystem(org.apache.flink.core.fs.FileSystem, org.apache.flink.core.fs.Path, org.apache.flink.core.fs.Path, org.apache.flink.core.fs.Path, int) or FileMergingSnapshotManager.registerSubtaskForSharedStates(org.apache.flink.runtime.checkpoint.filemerging.FileMergingSnapshotManager.SubtaskKey).
protected abstract PhysicalFile	getOrCreatePhysicalFileForCheckpoint(FileMergingSnapshotManager.SubtaskKey subtaskKey, long checkpointId, CheckpointedStateScope scope)	Get a reused physical file or create one.
void	initFileSystem(org.apache.flink.core.fs.FileSystem fileSystem, org.apache.flink.core.fs.Path checkpointBaseDir, org.apache.flink.core.fs.Path sharedStateDir, org.apache.flink.core.fs.Path taskOwnedStateDir, int writeBufferSize)	Initialize the file system, recording the checkpoint path the manager should work with.
void	notifyCheckpointAborted(FileMergingSnapshotManager.SubtaskKey subtaskKey, long checkpointId)	This method is called as a notification once a distributed checkpoint has been aborted.
void	notifyCheckpointComplete(FileMergingSnapshotManager.SubtaskKey subtaskKey, long checkpointId)	Notifies the manager that the checkpoint with the given checkpointId completed and was committed.
void	notifyCheckpointStart(FileMergingSnapshotManager.SubtaskKey subtaskKey, long checkpointId)	SubtaskCheckpointCoordinatorImpl use this method let the file merging manager know an ongoing checkpoint may reference the managed dirs.
void	notifyCheckpointSubsumed(FileMergingSnapshotManager.SubtaskKey subtaskKey, long checkpointId)	This method is called as a notification once a distributed checkpoint has been subsumed.
void	registerSubtaskForSharedStates(FileMergingSnapshotManager.SubtaskKey subtaskKey)	Register a subtask and create the managed directory for shared states.
void	restoreStateHandles(long checkpointId, FileMergingSnapshotManager.SubtaskKey subtaskKey, Stream<SegmentFileStateHandle> stateHandles)	Restore and re-register the SegmentFileStateHandles into FileMergingSnapshotManager.
protected abstract void	returnPhysicalFileForNextReuse(FileMergingSnapshotManager.SubtaskKey subtaskKey, long checkpointId, PhysicalFile physicalFile)	Try to return an existing physical file to the manager for next reuse.
void	reusePreviousStateHandle(long checkpointId, Collection<? extends StreamStateHandle> stateHandles)	A callback method which is called when previous state handles are reused by following checkpoint(s).
void	unregisterSubtask(FileMergingSnapshotManager.SubtaskKey subtaskKey)	Unregister a subtask.

Methods inherited from class java.lang.Object

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

Field Details

ioExecutor

protected final Executor ioExecutor

The executor for I/O operations in this manager.

lock

protected final Object lock

Guard for initFileSystem(org.apache.flink.core.fs.FileSystem, org.apache.flink.core.fs.Path, org.apache.flink.core.fs.Path, org.apache.flink.core.fs.Path, int), restoreStateHandles(long, org.apache.flink.runtime.checkpoint.filemerging.FileMergingSnapshotManager.SubtaskKey, java.util.stream.Stream<org.apache.flink.runtime.state.filemerging.SegmentFileStateHandle>) and uploadedStates.

uploadedStates

protected TreeMap<Long,Set<LogicalFile>> uploadedStates

fs

protected org.apache.flink.core.fs.FileSystem fs

The FileSystem that this manager works on.

checkpointDir

protected org.apache.flink.core.fs.Path checkpointDir

sharedStateDir

protected org.apache.flink.core.fs.Path sharedStateDir

taskOwnedStateDir

protected org.apache.flink.core.fs.Path taskOwnedStateDir

writeBufferSize

protected int writeBufferSize

The buffer size for writing files to the file system.

shouldSyncAfterClosingLogicalFile

protected boolean shouldSyncAfterClosingLogicalFile

File-system dependent value. Mark whether the file system this manager running on need sync for visibility. If true, DO a file sync after writing each segment .

maxPhysicalFileSize

protected long maxPhysicalFileSize

Max size for a physical file.

filePoolType

protected PhysicalFilePool.Type filePoolType

Type of physical file pool.

maxSpaceAmplification

protected final float maxSpaceAmplification

physicalFileDeleter

protected PhysicalFile.PhysicalFileDeleter physicalFileDeleter

managedExclusiveStateDir

protected org.apache.flink.core.fs.Path managedExclusiveStateDir

The private state files are merged across subtasks, there is only one directory for merged-files within one TM per job.

managedExclusiveStateDirHandle

protected FileMergingSnapshotManagerBase.DirectoryHandleWithReferenceTrack managedExclusiveStateDirHandle

The DirectoryStreamStateHandle with it ongoing checkpoint reference count for private state directory, one for each taskmanager and job.

spaceStat

protected FileMergingSnapshotManager.SpaceStat spaceStat

The current space statistic, updated on file creation/deletion.

metricGroup

protected FileMergingMetricGroup metricGroup

The metric group for file merging snapshot manager.

Constructor Details

FileMergingSnapshotManagerBase

public FileMergingSnapshotManagerBase(String id,
 long maxFileSize,
 PhysicalFilePool.Type filePoolType,
 float maxSpaceAmplification,
 Executor ioExecutor,
 org.apache.flink.metrics.MetricGroup parentMetricGroup)

Method Details

initFileSystem

public void initFileSystem(org.apache.flink.core.fs.FileSystem fileSystem,
 org.apache.flink.core.fs.Path checkpointBaseDir,
 org.apache.flink.core.fs.Path sharedStateDir,
 org.apache.flink.core.fs.Path taskOwnedStateDir,
 int writeBufferSize)
                    throws IllegalArgumentException

Description copied from interface: FileMergingSnapshotManager

Initialize the file system, recording the checkpoint path the manager should work with.

 The layout of checkpoint directory:
 /user-defined-checkpoint-dir
     /{job-id} (checkpointBaseDir)
         |
         + --shared/
             |
             + --subtask-1/
                 + -- merged shared state files
             + --subtask-2/
                 + -- merged shared state files
         + --taskowned/
             + -- merged private state files
         + --chk-1/
         + --chk-2/
         + --chk-3/
 

The reason why initializing directories in this method instead of the constructor is that the FileMergingSnapshotManager itself belongs to the TaskStateManager, which is initialized when receiving a task, while the base directories for checkpoint are created by FsCheckpointStorageAccess when the state backend initializes per subtask. After the checkpoint directories are initialized, the managed subdirectories are initialized here.

Note: This method may be called several times, the implementation should ensure idempotency, and throw IllegalArgumentException when any of the path in params change across function calls.

Specified by:

initFileSystem in interface FileMergingSnapshotManager

Parameters:

fileSystem - The filesystem to write to.

checkpointBaseDir - The base directory for checkpoints.

sharedStateDir - The directory for shared checkpoint data.

taskOwnedStateDir - The name of the directory for state not owned/released by the master, but by the TaskManagers.

writeBufferSize - The buffer size for writing files to the file system.

Throws:

IllegalArgumentException - thrown if these three paths are not deterministic across calls.

registerSubtaskForSharedStates

public void registerSubtaskForSharedStates(FileMergingSnapshotManager.SubtaskKey subtaskKey)

Description copied from interface: FileMergingSnapshotManager

Register a subtask and create the managed directory for shared states.

Specified by:

registerSubtaskForSharedStates in interface FileMergingSnapshotManager

Parameters:

subtaskKey - the subtask key identifying a subtask.

See Also:

• for layout information.

unregisterSubtask

public void unregisterSubtask(FileMergingSnapshotManager.SubtaskKey subtaskKey)

Description copied from interface: FileMergingSnapshotManager

Unregister a subtask.

Specified by:

unregisterSubtask in interface FileMergingSnapshotManager

Parameters:

subtaskKey - the subtask key identifying a subtask.

createLogicalFile

protected LogicalFile createLogicalFile(@Nonnull
 PhysicalFile physicalFile,
 long startOffset,
 long length,
 @Nonnull
 FileMergingSnapshotManager.SubtaskKey subtaskKey)

Create a logical file on a physical file.

Parameters:

physicalFile - the underlying physical file.

startOffset - the offset in the physical file that the logical file starts from.

length - the length of the logical file.

subtaskKey - the id of the subtask that the logical file belongs to.

Returns:

the created logical file.

createPhysicalFile

@Nonnull
protected PhysicalFile createPhysicalFile(FileMergingSnapshotManager.SubtaskKey subtaskKey,
 CheckpointedStateScope scope)
                                   throws IOException

Create a physical file in right location (managed directory), which is specified by scope of this checkpoint and current subtask.

Parameters:

subtaskKey - the FileMergingSnapshotManager.SubtaskKey of current subtask.

scope - the scope of the checkpoint.

Returns:

the created physical file.

Throws:

IOException - if anything goes wrong with file system.

createCheckpointStateOutputStream

public FileMergingCheckpointStateOutputStream createCheckpointStateOutputStream(FileMergingSnapshotManager.SubtaskKey subtaskKey,
 long checkpointId,
 CheckpointedStateScope scope)

Description copied from interface: FileMergingSnapshotManager

Create a new FileMergingCheckpointStateOutputStream. According to the file merging strategy, the streams returned by multiple calls to this function may share the same underlying physical file, and each stream writes to a segment of the physical file.

Specified by:

createCheckpointStateOutputStream in interface FileMergingSnapshotManager

Parameters:

subtaskKey - The subtask key identifying the subtask.

checkpointId - ID of the checkpoint.

scope - The state's scope, whether it is exclusive or shared.

Returns:

An output stream that writes state for the given checkpoint.

generatePhysicalFilePath

protected org.apache.flink.core.fs.Path generatePhysicalFilePath(org.apache.flink.core.fs.Path dirPath)

Generate a file path for a physical file.

Parameters:

dirPath - the parent directory path for the physical file.

Returns:

the generated file path for a physical file.

deletePhysicalFile

protected final void deletePhysicalFile(org.apache.flink.core.fs.Path filePath,
 long size)

Delete a physical file by given file path. Use the io executor to do the deletion.

Parameters:

filePath - the given file path to delete.

createPhysicalPool

protected final PhysicalFilePool createPhysicalPool()

Create physical pool by filePoolType.

Returns:

physical file pool.

getOrCreatePhysicalFileForCheckpoint

@Nonnull
protected abstract PhysicalFile getOrCreatePhysicalFileForCheckpoint(FileMergingSnapshotManager.SubtaskKey subtaskKey,
 long checkpointId,
 CheckpointedStateScope scope)
                                                              throws IOException

Get a reused physical file or create one. This will be called in checkpoint output stream creation logic.

Basic logic of file reusing: whenever a physical file is needed, this method is called with necessary information provided for acquiring a file. The file will not be reused until it is written and returned to the reused pool by calling returnPhysicalFileForNextReuse(org.apache.flink.runtime.checkpoint.filemerging.FileMergingSnapshotManager.SubtaskKey, long, org.apache.flink.runtime.checkpoint.filemerging.PhysicalFile).

Parameters:

subtaskKey - the subtask key for the caller

checkpointId - the checkpoint id

scope - checkpoint scope

Returns:

the requested physical file.

Throws:

IOException - thrown if anything goes wrong with file system.

returnPhysicalFileForNextReuse

protected abstract void returnPhysicalFileForNextReuse(FileMergingSnapshotManager.SubtaskKey subtaskKey,
 long checkpointId,
 PhysicalFile physicalFile)
                                                throws IOException

Try to return an existing physical file to the manager for next reuse. If this physical file is no longer needed (for reusing), it will be closed.

Basic logic of file reusing, see getOrCreatePhysicalFileForCheckpoint(org.apache.flink.runtime.checkpoint.filemerging.FileMergingSnapshotManager.SubtaskKey, long, org.apache.flink.runtime.state.CheckpointedStateScope).

Parameters:

subtaskKey - the subtask key for the caller

checkpointId - in which checkpoint this physical file is requested.

physicalFile - the returning checkpoint

Throws:

IOException - thrown if anything goes wrong with file system.

See Also:

• getOrCreatePhysicalFileForCheckpoint(SubtaskKey, long, CheckpointedStateScope)

discardCheckpoint

protected void discardCheckpoint(long checkpointId)
                          throws IOException

The callback which will be triggered when all subtasks discarded (aborted or subsumed).

Parameters:

checkpointId - the discarded checkpoint id.

Throws:

IOException - if anything goes wrong with file system.

notifyCheckpointStart

public void notifyCheckpointStart(FileMergingSnapshotManager.SubtaskKey subtaskKey,
 long checkpointId)

SubtaskCheckpointCoordinatorImpl use this method let the file merging manager know an ongoing checkpoint may reference the managed dirs.

Specified by:

notifyCheckpointStart in interface FileMergingSnapshotManager

Parameters:

subtaskKey - the subtask key identifying the subtask.

checkpointId - The ID of the checkpoint that has been started.

notifyCheckpointComplete

public void notifyCheckpointComplete(FileMergingSnapshotManager.SubtaskKey subtaskKey,
 long checkpointId)
                              throws Exception

Description copied from interface: FileMergingSnapshotManager

Notifies the manager that the checkpoint with the given checkpointId completed and was committed.

Specified by:

notifyCheckpointComplete in interface FileMergingSnapshotManager

Parameters:

subtaskKey - the subtask key identifying the subtask.

checkpointId - The ID of the checkpoint that has been completed.

Throws:

Exception - thrown if anything goes wrong with the listener.

notifyCheckpointAborted

public void notifyCheckpointAborted(FileMergingSnapshotManager.SubtaskKey subtaskKey,
 long checkpointId)
                             throws Exception

Description copied from interface: FileMergingSnapshotManager

This method is called as a notification once a distributed checkpoint has been aborted.

Specified by:

notifyCheckpointAborted in interface FileMergingSnapshotManager

Parameters:

subtaskKey - the subtask key identifying the subtask.

checkpointId - The ID of the checkpoint that has been completed.

Throws:

Exception - thrown if anything goes wrong with the listener.

notifyCheckpointSubsumed

public void notifyCheckpointSubsumed(FileMergingSnapshotManager.SubtaskKey subtaskKey,
 long checkpointId)
                              throws Exception

Description copied from interface: FileMergingSnapshotManager

This method is called as a notification once a distributed checkpoint has been subsumed.

Specified by:

notifyCheckpointSubsumed in interface FileMergingSnapshotManager

Parameters:

subtaskKey - the subtask key identifying the subtask.

checkpointId - The ID of the checkpoint that has been completed.

Throws:

Exception - thrown if anything goes wrong with the listener.

reusePreviousStateHandle

public void reusePreviousStateHandle(long checkpointId,
 Collection<? extends StreamStateHandle> stateHandles)

Description copied from interface: FileMergingSnapshotManager

A callback method which is called when previous state handles are reused by following checkpoint(s).

Specified by:

reusePreviousStateHandle in interface FileMergingSnapshotManager

Parameters:

checkpointId - the checkpoint that reuses the handles.

stateHandles - the handles to be reused.

couldReusePreviousStateHandle

public boolean couldReusePreviousStateHandle(StreamStateHandle stateHandle)

Description copied from interface: FileMergingSnapshotManager

Check whether previous state handles could further be reused considering the space amplification.

Specified by:

couldReusePreviousStateHandle in interface FileMergingSnapshotManager

Parameters:

stateHandle - the handle to be reused.

discardSingleLogicalFile

public void discardSingleLogicalFile(LogicalFile logicalFile,
 long checkpointId)
                              throws IOException

Throws:

IOException

getManagedDir

public org.apache.flink.core.fs.Path getManagedDir(FileMergingSnapshotManager.SubtaskKey subtaskKey,
 CheckpointedStateScope scope)

Description copied from interface: FileMergingSnapshotManager

Get the managed directory of the file-merging snapshot manager, created in FileMergingSnapshotManager.initFileSystem(org.apache.flink.core.fs.FileSystem, org.apache.flink.core.fs.Path, org.apache.flink.core.fs.Path, org.apache.flink.core.fs.Path, int) or FileMergingSnapshotManager.registerSubtaskForSharedStates(org.apache.flink.runtime.checkpoint.filemerging.FileMergingSnapshotManager.SubtaskKey).

Specified by:

getManagedDir in interface FileMergingSnapshotManager

Parameters:

subtaskKey - the subtask key identifying the subtask.

scope - the checkpoint scope.

Returns:

the managed directory for one subtask in specified checkpoint scope.

getManagedDirStateHandle

public DirectoryStreamStateHandle getManagedDirStateHandle(FileMergingSnapshotManager.SubtaskKey subtaskKey,
 CheckpointedStateScope scope)

Description copied from interface: FileMergingSnapshotManager

Get the DirectoryStreamStateHandle of the managed directory, created in FileMergingSnapshotManager.initFileSystem(org.apache.flink.core.fs.FileSystem, org.apache.flink.core.fs.Path, org.apache.flink.core.fs.Path, org.apache.flink.core.fs.Path, int) or FileMergingSnapshotManager.registerSubtaskForSharedStates(org.apache.flink.runtime.checkpoint.filemerging.FileMergingSnapshotManager.SubtaskKey).

Specified by:

getManagedDirStateHandle in interface FileMergingSnapshotManager

Parameters:

subtaskKey - the subtask key identifying the subtask.

scope - the checkpoint scope.

Returns:

the DirectoryStreamStateHandle for one subtask in specified checkpoint scope.

close

public void close()
           throws IOException

Specified by:

close in interface AutoCloseable

Specified by:

close in interface Closeable

Throws:

IOException

getId

@VisibleForTesting
public String getId()

restoreStateHandles

public void restoreStateHandles(long checkpointId,
 FileMergingSnapshotManager.SubtaskKey subtaskKey,
 Stream<SegmentFileStateHandle> stateHandles)

Description copied from interface: FileMergingSnapshotManager

Restore and re-register the SegmentFileStateHandles into FileMergingSnapshotManager.

Specified by:

restoreStateHandles in interface FileMergingSnapshotManager

Parameters:

checkpointId - the restored checkpoint id.

subtaskKey - the subtask key identifying the subtask.

stateHandles - the restored segment file handles.

getLogicalFile

@VisibleForTesting
public LogicalFile getLogicalFile(LogicalFile.LogicalFileId fileId)