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package eu.shiftforward.apso.aws
import com.amazonaws.auth.AWSCredentials
import com.amazonaws.services.s3.{ AmazonS3, AmazonS3Client }
import com.amazonaws.services.s3.model._
import eu.shiftforward.apso.Logging
import scala.collection.convert.WrapAsScala._
/**
* A representation of Amazon's S3 service. This class wraps an
* [[com.amazonaws.services.s3.AmazonS3]] instance and provides a higher level interface for
* querying the information about the buckets and their objects.
* @param credentials optional AWS credentials to use. If the parameter is not supplied, they will
* be retrieved from the [[eu.shiftforward.apso.aws.CredentialStore]].
*/
class S3(credentials: AWSCredentials = CredentialStore.getCredentials) extends Logging {
/**
* The underlying [[com.amazonaws.services.s3.AmazonS3]] instance.
*/
val client: AmazonS3 = new AmazonS3Client(credentials)
/**
* Returns a list of all the buckets listable with this object's credentials.
* @return a list of all the buckets listable with this object's credentials.
*/
def buckets: Seq[Bucket] = client.listBuckets()
/**
* Returns the representation of an object in a bucket, if it exists.
* @param bucketName the name of the bucket
* @param objName the name of the object
* @return the object wrapped in a `Some` if that object exists, `None` otherwise.
*/
def apply(bucketName: String, objName: String): Option[S3Object] = try {
Some(client.getObject(bucketName, objName))
} catch {
case e: AmazonS3Exception => None
}
/**
* Returns the metadata of an object in a bucket, if it exists.
* @param bucketName the name of the bucket
* @param objName the name of the object
* @return the object metadata wrapped in a `Some` if that object exists, `None` otherwise.
*/
def metadata(bucketName: String, objName: String): Option[ObjectMetadata] = try {
Some(client.getObjectMetadata(bucketName, objName))
} catch {
case e: AmazonS3Exception => None
}
/**
* Returns the tags associated with a bucket.
* @param bucket the bucket object
* @return a map containing the tags associated with the given bucket. If the bucket doesn't
* exist, an empty map is returned.
*/
@inline def bucketTags(bucket: Bucket): Map[String, String] = bucketTags(bucket.getName)
/**
* Returns the tags associated with a bucket.
* @param bucketName the name of the bucket
* @return a map containing the tags associated with the given bucket. If the bucket doesn't
* exist, an empty map is returned.
*/
def bucketTags(bucketName: String): Map[String, String] = {
Option(client.getBucketTaggingConfiguration(bucketName))
.map(_.getTagSet.getAllTags.toMap).getOrElse(Map())
}
/**
* Returns the first object in a bucket, optionally with a given prefix and after a given marker,
* if it exists.
* @param bucketName the name of the bucket
* @param prefix the prefix of the object to return, or `null` for no prefix
* @param marker the marker from which the search is to be done, or `null` to search from the
* beginning of the bucket
* @return the first object in a bucket with the given prefix after the given marker wrapped in a
* `Some` if such an object exists, `None` otherwise.
*/
@inline def headObject(bucketName: String, prefix: String = null, marker: String = null): Option[S3ObjectSummary] =
objects(bucketName, prefix, marker).toStream.headOption
/**
* Returns the objects in a bucket, optionally with a given prefix and after a given marker.
* @param bucketName the name of the bucket
* @param prefix the prefix of the objects to return, or `null` for no prefix
* @param marker the marker from which the search is to be done, or `null` to search from the
* beginning of the bucket
* @param maxKeys the maximum number of objects to return. As S3 can limit the number of objects
* returned in a single request, there is no guarantee that `maxKeys` objects will
* be returned, even if there is more than `maxKeys` objects in S3 with the
* specified constraints.
* @return a list with at most `maxKeys` objects in a bucket with the given prefix after the given
* marker.
*/
def objects(
bucketName: String,
prefix: String = null,
marker: String = null,
maxKeys: Int = 1): Iterator[S3ObjectSummary] = {
def loop(last: String, max: Int): Iterator[S3ObjectSummary] = {
val req = new ListObjectsRequest(bucketName, prefix, last, null, max)
val objs = client.listObjects(req).getObjectSummaries
if (objs.length == max || objs.length < 1000) objs.toIterator
else objs.toIterator ++ loop(objs.get(objs.length - 1).getKey, max - 1000)
}
loop(marker, maxKeys)
}
}
