org.apache.druid.segment.loading

Class StorageLocation

java.lang.Object

org.apache.druid.segment.loading.StorageLocation

public class StorageLocation
extends Object

This class is a very simple logical representation of a local path. It keeps track of files stored under the path via reserve(java.lang.String, org.apache.druid.timeline.DataSegment), so that the total size of stored files doesn't exceed the maxSizeBytes and available space is always kept smaller than freeSpaceToKeep. This class is thread-safe, so that multiple threads can update its state at the same time. One example usage is that a historical can use multiple threads to load different segments in parallel from deep storage.

Constructor Summary

Constructors

Constructor and Description
StorageLocation(File path, long maxSizeBytes, Double freeSpacePercent)

Method Summary

Modifier and Type	Method and Description
long	availableSizeBytes()
long	currSizeBytes()
File	getPath()
boolean	isReserved(String segmentDir)
void	maybeReserve(String segmentFilePathToAdd, DataSegment segment) Reserves space to store the given segment, only if it has not been done already.
boolean	release(String segmentFilePath, long segmentSize)
void	removeFile(File file) Remove a segment file from this location.
void	removeSegmentDir(File segmentDir, DataSegment segment) Remove a segment dir from this location.
File	reserve(String segmentDir, DataSegment segment) Reserves space to store the given segment.
File	reserve(String segmentFilePathToAdd, String segmentId, long segmentSize) Reserves space to store the given segment.
File	segmentDirectoryAsFile(String segmentDir)

Methods inherited from class java.lang.Object

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

Constructor Detail

StorageLocation

public StorageLocation(File path,
                       long maxSizeBytes,
                       @Nullable
                       Double freeSpacePercent)

Method Detail

getPath

public File getPath()

removeFile

public void removeFile(File file)

Remove a segment file from this location. The given file argument must be a file rather than directory.

removeSegmentDir

public void removeSegmentDir(File segmentDir,
                             DataSegment segment)

Remove a segment dir from this location. The segment size is subtracted from currSizeBytes.

reserve

@Nullable
public File reserve(String segmentDir,
                              DataSegment segment)

Reserves space to store the given segment. The segment size is added to currSizeBytes. If it succeeds, it returns a file for the given segmentDir in this storage location. Returns null otherwise.

isReserved

public boolean isReserved(String segmentDir)

segmentDirectoryAsFile

public File segmentDirectoryAsFile(String segmentDir)

maybeReserve

public void maybeReserve(String segmentFilePathToAdd,
                         DataSegment segment)

Reserves space to store the given segment, only if it has not been done already. This can be used when segment is already downloaded on the disk. Unlike reserve(String, DataSegment), this function skips the check on disk availability. We also account for segment usage even if available size dips below 0. Such a situation indicates a configuration problem or a bug and we don't let segment loading fail because of this.

reserve

@Nullable
public File reserve(String segmentFilePathToAdd,
                              String segmentId,
                              long segmentSize)

Reserves space to store the given segment. If it succeeds, it returns a file for the given segmentFilePathToAdd in this storage location. Returns null otherwise.

release

public boolean release(String segmentFilePath,
                       long segmentSize)

availableSizeBytes

public long availableSizeBytes()

currSizeBytes

public long currSizeBytes()