com.google.cloud.hadoop.gcsio

Interface GoogleCloudStorage

All Known Implementing Classes:

CacheSupplementedGoogleCloudStorage, GoogleCloudStorageImpl, MetadataReadOnlyGoogleCloudStorage, ThrottledGoogleCloudStorage

public interface GoogleCloudStorage

Interface for exposing the Google Cloud Storage API behavior in a way more amenable to writing filesystem semantics on top of it, without having to deal with API-specific considerations such as HttpTransports, credentials, network errors, batching, etc.

Please read the following document to get familiarity with basic GCS concepts: https://developers.google.com/storage/docs/concepts-techniques

Field Summary

Fields

Modifier and Type	Field and Description
static String	PATH_DELIMITER

Method Summary

Methods

Modifier and Type	Method and Description
void	close() Releases resources used by this instance.
void	copy(String srcBucketName, List<String> srcObjectNames, String dstBucketName, List<String> dstObjectNames) Copies metadata of the given objects.
WritableByteChannel	create(StorageResourceId resourceId) Creates and opens an object for writing.
WritableByteChannel	create(StorageResourceId resourceId, CreateObjectOptions options) Creates and opens an object for writing.
void	create(String bucketName) Creates a bucket.
void	createEmptyObject(StorageResourceId resourceId) Creates an empty object, useful for placeholders representing, for example, directories.
void	createEmptyObject(StorageResourceId resourceId, CreateObjectOptions options) Creates an empty object, useful for placeholders representing, for example, directories.
void	createEmptyObjects(List<StorageResourceId> resourceIds) Creates a list of empty objects; see createEmptyObject(StorageResourceId) for the single-item version of this method.
void	createEmptyObjects(List<StorageResourceId> resourceIds, CreateObjectOptions options) Creates a list of empty objects; see createEmptyObject(StorageResourceId) for the single-item version of this method.
void	deleteBuckets(List<String> bucketNames) Deletes a list of buckets.
void	deleteObjects(List<StorageResourceId> fullObjectNames) Deletes the given objects.
GoogleCloudStorageItemInfo	getItemInfo(StorageResourceId resourceId) Gets information about an object or a bucket.
List<GoogleCloudStorageItemInfo>	getItemInfos(List<StorageResourceId> resourceIds) Gets information about multiple objects and/or buckets.
List<GoogleCloudStorageItemInfo>	listBucketInfo() Gets a list of GoogleCloudStorageItemInfo for all buckets of this project.
List<String>	listBucketNames() Gets a list of names of buckets in this project.
List<GoogleCloudStorageItemInfo>	listObjectInfo(String bucketName, String objectNamePrefix, String delimiter) Same name-matching semantics as listObjectNames except this method retrieves the full GoogleCloudStorageFileInfo for each item as well; generally the info is already available from the same "list()" calls, so the only additional cost is dispatching an extra batch request to retrieve object metadata for all listed *directories*, since these are originally listed as String prefixes without attached metadata.
List<String>	listObjectNames(String bucketName, String objectNamePrefix, String delimiter) Gets names of objects contained in the given bucket and whose names begin with the given prefix.
SeekableReadableByteChannel	open(StorageResourceId resourceId) Opens an object for reading.
List<GoogleCloudStorageItemInfo>	updateItems(List<UpdatableItemInfo> itemInfoList) Attempt to update metadata of the objects referenced within the passed itemInfo objects.
void	waitForBucketEmpty(String bucketName) Waits for the given bucket to be empty.

Field Detail

PATH_DELIMITER

static final String PATH_DELIMITER

See Also:

Constant Field Values

Method Detail

create

WritableByteChannel create(StorageResourceId resourceId)
                           throws IOException

Creates and opens an object for writing. The bucket must already exist. If the object already exists, it is deleted.

Parameters:

resourceId - identifies a StorageObject

Returns:

a channel for writing to the given object

Throws:

IOException - on IO error

create

WritableByteChannel create(StorageResourceId resourceId,
                         CreateObjectOptions options)
                           throws IOException

Creates and opens an object for writing. The bucket must already exist.

Parameters:

resourceId - identifies a StorageObject

options - Options to use when creating the object

Returns:

a channel for writing to the given object

Throws:

IOException - on IO error

createEmptyObject

void createEmptyObject(StorageResourceId resourceId)
                       throws IOException

Creates an empty object, useful for placeholders representing, for example, directories. The bucket must already exist. If the object already exists, it is overwritten.

Parameters:

resourceId - identifies a StorageObject

Throws:

IOException - on IO error

createEmptyObject

void createEmptyObject(StorageResourceId resourceId,
                     CreateObjectOptions options)
                       throws IOException

Creates an empty object, useful for placeholders representing, for example, directories. The bucket must already exist. If the object already exists, it is overwritten.

Parameters:

resourceId - identifies a StorageObject

options - options to use when creating the object

Throws:

IOException - on IO error

createEmptyObjects

void createEmptyObjects(List<StorageResourceId> resourceIds)
                        throws IOException

Creates a list of empty objects; see createEmptyObject(StorageResourceId) for the single-item version of this method. Implementations may use different flow than the single-item version for greater efficiency.

Throws:

IOException

createEmptyObjects

void createEmptyObjects(List<StorageResourceId> resourceIds,
                      CreateObjectOptions options)
                        throws IOException

Creates a list of empty objects; see createEmptyObject(StorageResourceId) for the single-item version of this method. Implementations may use different flow than the single-item version for greater efficiency.

Throws:

IOException

open

SeekableReadableByteChannel open(StorageResourceId resourceId)
                                 throws IOException

Opens an object for reading.

Parameters:

resourceId - identifies a StorageObject

Returns:

a channel for reading from the given object

Throws:

FileNotFoundException - if the given object does not exist

IOException - if object exists but cannot be opened

create

void create(String bucketName)
            throws IOException

Creates a bucket.

Parameters:

bucketName - name of the bucket to create

Throws:

IOException - on IO error

deleteBuckets

void deleteBuckets(List<String> bucketNames)
                   throws IOException

Deletes a list of buckets. Does not throw any exception for "bucket not found" errors.

Parameters:

bucketNames - name of the buckets to delete

Throws:

FileNotFoundException - if the given bucket does not exist

IOException - on IO error

deleteObjects

void deleteObjects(List<StorageResourceId> fullObjectNames)
                   throws IOException

Deletes the given objects. Does not throw any exception for "object not found" errors.

Parameters:

fullObjectNames - names of objects to delete with their respective bucketNames.

Throws:

FileNotFoundException - if the given object does not exist

IOException - if object exists but cannot be deleted

copy

void copy(String srcBucketName,
        List<String> srcObjectNames,
        String dstBucketName,
        List<String> dstObjectNames)
          throws IOException

Copies metadata of the given objects. After the copy is successfully complete, each object blob is reachable by two different names. Copying between two different locations or between two different storage classes is not allowed.

Parameters:

srcBucketName - name of the bucket containing the objects to copy

srcObjectNames - names of the objects to copy

dstBucketName - name of the bucket to copy to

dstObjectNames - names of the objects after copy

Throws:

FileNotFoundException - if the source object or the destination bucket does not exist

IOException - in all other error cases

listBucketNames

List<String> listBucketNames()
                             throws IOException

Gets a list of names of buckets in this project.

Throws:

IOException

listBucketInfo

List<GoogleCloudStorageItemInfo> listBucketInfo()
                                                throws IOException

Gets a list of GoogleCloudStorageItemInfo for all buckets of this project. This is no more expensive than calling listBucketNames(), since the list API for buckets already retrieves all the relevant bucket metadata.

Throws:

IOException

listObjectNames

List<String> listObjectNames(String bucketName,
                           String objectNamePrefix,
                           String delimiter)
                             throws IOException

Gets names of objects contained in the given bucket and whose names begin with the given prefix. Note: Although GCS does not implement a file system, it treats objects that contain a delimiter as different from other objects when listing objects. This will be clearer with an example. Consider a bucket with objects: o1, d1/, d1/o1, d1/o2 With prefix == null and delimiter == /, we get: d1/, o1 With prefix == null and delimiter == null, we get: o1, d1/, d1/o1, d1/o2 Thus when delimiter is null, the entire key name is considered an opaque string, otherwise only the part up to the first delimiter is considered.

Parameters:

bucketName - bucket name

objectNamePrefix - object name prefix or null if all objects in the bucket are desired

delimiter - delimiter to use (typically "/"), otherwise null

Returns:

list of object names

Throws:

IOException - on IO error

listObjectInfo

List<GoogleCloudStorageItemInfo> listObjectInfo(String bucketName,
                                              String objectNamePrefix,
                                              String delimiter)
                                                throws IOException

Same name-matching semantics as listObjectNames except this method retrieves the full GoogleCloudStorageFileInfo for each item as well; generally the info is already available from the same "list()" calls, so the only additional cost is dispatching an extra batch request to retrieve object metadata for all listed *directories*, since these are originally listed as String prefixes without attached metadata.

Parameters:

bucketName - bucket name

objectNamePrefix - object name prefix or null if all objects in the bucket are desired

delimiter - delimiter to use (typically "/"), otherwise null

Returns:

list of object info

Throws:

IOException - on IO error

getItemInfo

GoogleCloudStorageItemInfo getItemInfo(StorageResourceId resourceId)
                                       throws IOException

Gets information about an object or a bucket.

Parameters:

resourceId - identifies either root, a Bucket, or a StorageObject

Returns:

information about the given item

Throws:

IOException - on IO error

getItemInfos

List<GoogleCloudStorageItemInfo> getItemInfos(List<StorageResourceId> resourceIds)
                                              throws IOException

Gets information about multiple objects and/or buckets. Items which are "not found" will still have an entry in the returned list; exists() will return false for these entries.

Parameters:

resourceIds - names of the GCS StorageObjects or Buckets for which to retrieve info.

Returns:

information about the given resourceIds.

Throws:

IOException - on IO error

updateItems

List<GoogleCloudStorageItemInfo> updateItems(List<UpdatableItemInfo> itemInfoList)
                                             throws IOException

Attempt to update metadata of the objects referenced within the passed itemInfo objects.

Returns:

Updated GoogleCloudStorageItemInfo objects for the referenced objects.

Throws:

IOException - on IO error

close

void close()

Releases resources used by this instance.

waitForBucketEmpty

void waitForBucketEmpty(String bucketName)
                        throws IOException

Waits for the given bucket to be empty. Note: GCS only supports eventual consistency of object lists. When a user deletes a top-level directory recursively, the fact that all items have gone away is not reflected instantly. We retry and wait for that to happen.

Throws:

IOException