thredds.crawlabledataset.s3

Class CachingThreddsS3Client

java.lang.Object

thredds.crawlabledataset.s3.CachingThreddsS3Client

All Implemented Interfaces:

ThreddsS3Client

public class CachingThreddsS3Client
extends java.lang.Object
implements ThreddsS3Client

A ThreddsS3Client that wraps another ThreddsS3Client and caches its methods' return values for efficiency.

Since:

2015/08/22

Constructor Summary

Constructors

Constructor and Description
CachingThreddsS3Client(ThreddsS3Client threddsS3Client)
CachingThreddsS3Client(ThreddsS3Client threddsS3Client, com.google.common.cache.RemovalListener<S3URI,com.google.common.base.Optional<java.io.File>> removalListener)

Method Summary

Modifier and Type	Method and Description
void	clear() Discards all entries from all caches.
com.amazonaws.services.s3.model.ObjectMetadata	getObjectMetadata(S3URI s3uri) Gets the metadata for the specified Amazon S3 object without actually fetching the object itself.
com.amazonaws.services.s3.model.ObjectListing	listObjects(S3URI s3uri) Returns a listing of the objects located in the "virtual filesystem" at the specified URI.
java.io.File	saveObjectToFile(S3URI s3uri, java.io.File file) Gets the object metadata for the object stored in Amazon S3 under the specified bucket and key, and saves the object contents to the specified file.

Methods inherited from class java.lang.Object

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

Constructor Detail

CachingThreddsS3Client

public CachingThreddsS3Client(ThreddsS3Client threddsS3Client)

CachingThreddsS3Client

public CachingThreddsS3Client(ThreddsS3Client threddsS3Client,
                              com.google.common.cache.RemovalListener<S3URI,com.google.common.base.Optional<java.io.File>> removalListener)

Method Detail

getObjectMetadata

public com.amazonaws.services.s3.model.ObjectMetadata getObjectMetadata(S3URI s3uri)

Description copied from interface: ThreddsS3Client

Gets the metadata for the specified Amazon S3 object without actually fetching the object itself. The object metadata contains information such as content type, content disposition, etc., as well as custom user metadata that can be associated with an object in Amazon S3.

Specified by:

getObjectMetadata in interface ThreddsS3Client

Parameters:

s3uri - the Amazon S3 URI of the object whose metadata is being retrieved.

Returns:

all Amazon S3 object metadata for the specified object. Will be null if there is no S3 bucket with the specified name that has the specified key.

listObjects

public com.amazonaws.services.s3.model.ObjectListing listObjects(S3URI s3uri)

Description copied from interface: ThreddsS3Client

Returns a listing of the objects located in the "virtual filesystem" at the specified URI. s3uri.getKey() is interpreted as a path, and only objects (accessible via ObjectListing.getObjectSummaries()) or "directories" (accessible via ObjectListing.getCommonPrefixes()) that have that prefix will be part of the returned listing.

NOTE: To manage large result sets, Amazon S3 uses pagination to split them into multiple responses. As a consequence, this listing will only include the first 1000-or-so results.

TODO: Extend this API so that it allows the retrieval of more than 1000 results.

Specified by:

listObjects in interface ThreddsS3Client

Parameters:

s3uri - the Amazon S3 URI of the "virtual directory" whose objects are being retrieved.

Returns:

a listing of objects. Will be null if the specified URI does not denote an existing virtual directory. Otherwise, the result will be non-null and non-empty. That is, it will have at least one object summary or at least one common prefix.

See Also:

AmazonS3.listObjects(String)

saveObjectToFile

public java.io.File saveObjectToFile(S3URI s3uri,
                                     java.io.File file)
                              throws java.io.IOException

Gets the object metadata for the object stored in Amazon S3 under the specified bucket and key, and saves the object contents to the specified file.

WARNING: If the content at s3uri was previously saved using this method, and the old file to which it was saved is not the same as file, the object content will be copied to the new file and the old file will be deleted.

Specified by:

saveObjectToFile in interface ThreddsS3Client

Parameters:

s3uri - the Amazon S3 URI of the object whose content is being saved.

file - indicates the file (which might already exist) where to save the object content being downloading from Amazon S3.

Returns:

the file in which the Amazon S3 object's content was saved. Returns null if there is no S3 bucket with the specified name that has the specified key.

Throws:

java.io.IOException - if some I/O error occurred on the local filesystem while writing to file.

clear

public void clear()

Discards all entries from all caches. Any files created by saveObjectToFile(thredds.crawlabledataset.s3.S3URI, java.io.File) will be deleted.