org.apache.hadoop.fs.s3a.s3guard

Class LocalMetadataStore

java.lang.Object

org.apache.hadoop.fs.s3a.s3guard.LocalMetadataStore

All Implemented Interfaces:

Closeable, AutoCloseable, MetadataStore

public class LocalMetadataStore
extends Object
implements MetadataStore

This is a local, in-memory implementation of MetadataStore. This is not a coherent cache across processes. It is only locally-coherent. The purpose of this is for unit and integration testing. It could also be used to accelerate local-only operations where only one process is operating on a given object store, or multiple processes are accessing a read-only storage bucket. This MetadataStore does not enforce filesystem rules such as disallowing non-recursive removal of non-empty directories. It is assumed the caller already has to perform these sorts of checks. Contains one cache internally with time based eviction.

Field Summary

Fields

Modifier and Type	Field and Description
static org.slf4j.Logger	LOG

Constructor Summary

Constructors

Constructor and Description
LocalMetadataStore()

Method Summary

Modifier and Type	Method and Description
void	close()
void	delete(org.apache.hadoop.fs.Path p) Deletes exactly one path, leaving a tombstone to prevent lingering, inconsistent copies of it from being listed.
void	deleteSubtree(org.apache.hadoop.fs.Path path) Deletes the entire sub-tree rooted at the given path, leaving tombstones to prevent lingering, inconsistent copies of it from being listed.
void	destroy() Destroy all resources associated with the metadata store.
void	forgetMetadata(org.apache.hadoop.fs.Path p) Removes the record of exactly one path.
PathMetadata	get(org.apache.hadoop.fs.Path p) Gets metadata for a path.
PathMetadata	get(org.apache.hadoop.fs.Path p, boolean wantEmptyDirectoryFlag) Gets metadata for a path.
Map<String,String>	getDiagnostics() Get any diagnostics information from a store, as a list of (key, value) tuples for display.
void	initialize(org.apache.hadoop.conf.Configuration conf) Performs one-time initialization of the metadata store via configuration.
void	initialize(org.apache.hadoop.fs.FileSystem fileSystem) Performs one-time initialization of the metadata store.
DirListingMetadata	listChildren(org.apache.hadoop.fs.Path p) Lists metadata for all direct children of a path.
void	move(Collection<org.apache.hadoop.fs.Path> pathsToDelete, Collection<PathMetadata> pathsToCreate) Record the effects of a FileSystem.rename(Path, Path) in the MetadataStore.
void	prune(long modTime) Clear any metadata older than a specified time from the repository.
void	prune(long modTime, String keyPrefix) Same as MetadataStore.prune(long), but with an additional keyPrefix parameter to filter the pruned keys with a prefix.
void	put(Collection<PathMetadata> metas) Saves metadata for any number of paths.
void	put(DirListingMetadata meta) Save directory listing metadata.
void	put(PathMetadata meta) Saves metadata for exactly one path.
String	toString()
void	updateParameters(Map<String,String> parameters) Tune/update parameters for an existing table.

Methods inherited from class java.lang.Object

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

Field Detail

LOG

public static final org.slf4j.Logger LOG

Constructor Detail

LocalMetadataStore

public LocalMetadataStore()

Method Detail

initialize

public void initialize(org.apache.hadoop.fs.FileSystem fileSystem)
                throws IOException

Description copied from interface: MetadataStore

Performs one-time initialization of the metadata store.

Specified by:

initialize in interface MetadataStore

Parameters:

fileSystem - FileSystem associated with the MetadataStore

Throws:

IOException - if there is an error

initialize

public void initialize(org.apache.hadoop.conf.Configuration conf)
                throws IOException

Description copied from interface: MetadataStore

Performs one-time initialization of the metadata store via configuration.

Specified by:

initialize in interface MetadataStore

Parameters:

conf - Configuration.

Throws:

IOException - if there is an error

See Also:

MetadataStore.initialize(FileSystem)

toString

public String toString()

Overrides:

toString in class Object

delete

public void delete(org.apache.hadoop.fs.Path p)
            throws IOException

Description copied from interface: MetadataStore

Deletes exactly one path, leaving a tombstone to prevent lingering, inconsistent copies of it from being listed.

Specified by:

delete in interface MetadataStore

Parameters:

p - the path to delete

Throws:

IOException - if there is an error

forgetMetadata

public void forgetMetadata(org.apache.hadoop.fs.Path p)
                    throws IOException

Description copied from interface: MetadataStore

Removes the record of exactly one path. Does not leave a tombstone (see MetadataStore.delete(Path). It is currently intended for testing only, and a need to use it as part of normal FileSystem usage is not anticipated.

Specified by:

forgetMetadata in interface MetadataStore

Parameters:

p - the path to delete

Throws:

IOException - if there is an error

deleteSubtree

public void deleteSubtree(org.apache.hadoop.fs.Path path)
                   throws IOException

Description copied from interface: MetadataStore

Deletes the entire sub-tree rooted at the given path, leaving tombstones to prevent lingering, inconsistent copies of it from being listed. In addition to affecting future calls to MetadataStore.get(Path), implementations must also update any stored DirListingMetadata objects which track the parent of this file.

Specified by:

deleteSubtree in interface MetadataStore

Parameters:

path - the root of the sub-tree to delete

Throws:

IOException - if there is an error

get

public PathMetadata get(org.apache.hadoop.fs.Path p)
                 throws IOException

Description copied from interface: MetadataStore

Gets metadata for a path.

Specified by:

get in interface MetadataStore

Parameters:

p - the path to get

Returns:

metadata for path, null if not found

Throws:

IOException - if there is an error

get

public PathMetadata get(org.apache.hadoop.fs.Path p,
                        boolean wantEmptyDirectoryFlag)
                 throws IOException

Description copied from interface: MetadataStore

Gets metadata for a path. Alternate method that includes a hint whether or not the MetadataStore should do work to compute the value for PathMetadata.isEmptyDirectory(). Since determining emptiness may be an expensive operation, this can save wasted work.

Specified by:

get in interface MetadataStore

Parameters:

p - the path to get

wantEmptyDirectoryFlag - Set to true to give a hint to the MetadataStore that it should try to compute the empty directory flag.

Returns:

metadata for path, null if not found

Throws:

IOException - if there is an error

listChildren

public DirListingMetadata listChildren(org.apache.hadoop.fs.Path p)
                                throws IOException

Description copied from interface: MetadataStore

Lists metadata for all direct children of a path.

Specified by:

listChildren in interface MetadataStore

Parameters:

p - the path to list

Returns:

metadata for all direct children of path which are being tracked by the MetadataStore, or null if the path was not found in the MetadataStore.

Throws:

IOException - if there is an error

move

public void move(Collection<org.apache.hadoop.fs.Path> pathsToDelete,
                 Collection<PathMetadata> pathsToCreate)
          throws IOException

Description copied from interface: MetadataStore

Record the effects of a FileSystem.rename(Path, Path) in the MetadataStore. Clients provide explicit enumeration of the affected paths (recursively), before and after the rename. This operation is not atomic, unless specific implementations claim otherwise. On the need to provide an enumeration of directory trees instead of just source and destination paths: Since a MetadataStore does not have to track all metadata for the underlying storage system, and a new MetadataStore may be created on an existing underlying filesystem, this move() may be the first time the MetadataStore sees the affected paths. Therefore, simply providing src and destination paths may not be enough to record the deletions (under src path) and creations (at destination) that are happening during the rename().

Specified by:

move in interface MetadataStore

Parameters:

pathsToDelete - Collection of all paths that were removed from the source directory tree of the move.

pathsToCreate - Collection of all PathMetadata for the new paths that were created at the destination of the rename ().

Throws:

IOException - if there is an error

put

public void put(PathMetadata meta)
         throws IOException

Description copied from interface: MetadataStore

Saves metadata for exactly one path. Implementations may pre-create all the path's ancestors automatically. Implementations must update any DirListingMetadata objects which track the immediate parent of this file.

Specified by:

put in interface MetadataStore

Parameters:

meta - the metadata to save

Throws:

IOException - if there is an error

put

public void put(DirListingMetadata meta)
         throws IOException

Description copied from interface: MetadataStore

Save directory listing metadata. Callers may save a partial directory listing for a given path, or may store a complete and authoritative copy of the directory listing. MetadataStore implementations may subsequently keep track of all modifications to the directory contents at this path, and return authoritative results from subsequent calls to MetadataStore.listChildren(Path). See DirListingMetadata. Any authoritative results returned are only authoritative for the scope of the MetadataStore: A per-process MetadataStore, for example, would only show results visible to that process, potentially missing metadata updates (create, delete) made to the same path by another process.

Specified by:

put in interface MetadataStore

Parameters:

meta - Directory listing metadata.

Throws:

IOException - if there is an error

put

public void put(Collection<PathMetadata> metas)
         throws IOException

Description copied from interface: MetadataStore

Saves metadata for any number of paths. Semantics are otherwise the same as single-path puts.

Specified by:

put in interface MetadataStore

Parameters:

metas - the metadata to save

Throws:

IOException - if there is an error

close

public void close()
           throws IOException

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable

Throws:

IOException

destroy

public void destroy()
             throws IOException

Description copied from interface: MetadataStore

Destroy all resources associated with the metadata store. The destroyed resources can be DynamoDB tables, MySQL databases/tables, or HDFS directories. Any operations after calling this method may possibly fail. This operation is idempotent.

Specified by:

destroy in interface MetadataStore

Throws:

IOException - if there is an error

prune

public void prune(long modTime)
           throws IOException

Description copied from interface: MetadataStore

Clear any metadata older than a specified time from the repository. Implementations MUST clear file metadata, and MAY clear directory metadata (s3a itself does not track modification time for directories). Implementations may also choose to throw UnsupportedOperationException istead. Note that modification times should be in UTC, as returned by System.currentTimeMillis at the time of modification.

Specified by:

prune in interface MetadataStore

Parameters:

modTime - Oldest modification time to allow

Throws:

IOException - if there is an error

prune

public void prune(long modTime,
                  String keyPrefix)

Description copied from interface: MetadataStore

Same as MetadataStore.prune(long), but with an additional keyPrefix parameter to filter the pruned keys with a prefix.

Specified by:

prune in interface MetadataStore

Parameters:

modTime - Oldest modification time to allow

keyPrefix - The prefix for the keys that should be removed

getDiagnostics

public Map<String,String> getDiagnostics()
                                  throws IOException

Description copied from interface: MetadataStore

Get any diagnostics information from a store, as a list of (key, value) tuples for display. Arbitrary values; no guarantee of stability. These are for debugging and testing only.

Specified by:

getDiagnostics in interface MetadataStore

Returns:

a map of strings.

Throws:

IOException - if there is an error

updateParameters

public void updateParameters(Map<String,String> parameters)
                      throws IOException

Description copied from interface: MetadataStore

Tune/update parameters for an existing table.

Specified by:

updateParameters in interface MetadataStore

Parameters:

parameters - map of params to change.

Throws:

IOException - if there is an error