server/blob/blob-api/src/main/java/org/apache/james/blob/api/BlobStoreDAO.java

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package org.apache.james.blob.api;

import java.io.InputStream;
import java.nio.charset.StandardCharsets;

import org.reactivestreams.Publisher;

import com.google.common.io.ByteSource;

public interface BlobStoreDAO {

    /**
     * Reads a Blob based on its BucketName and its BlobId.
     *
     * @throws ObjectNotFoundException when the blobId or the bucket is not found
     * @throws ObjectStoreIOException when an unexpected IO error occurs
     */
    InputStream read(BucketName bucketName, BlobId blobId) throws ObjectStoreIOException, ObjectNotFoundException;


    /**
     * Reads a Blob based on its BucketName and its BlobId
     *
     * @return a Mono containing the content of the blob or
     *  an ObjectNotFoundException in its error channel when the blobId or the bucket is not found
     *  or an IOObjectStoreException when an unexpected IO error occurs
     */
    Publisher<byte[]> readBytes(BucketName bucketName, BlobId blobId);


    /**
     * Save the blob with the provided blob id, and overwrite the previous blob with the same id if it already exists
     * The bucket is created if it not already exists.
     * This operation should be atomic and isolated
     * Two blobs having the same blobId must have the same content
     * @return an empty Mono when the save succeed,
     *  otherwise an IOObjectStoreException in its error channel
     */
    Publisher<Void> save(BucketName bucketName, BlobId blobId, byte[] data);

    /**
     * @see #save(BucketName, BlobId, byte[])
     *
     * The InputStream should be closed after the call to this method
     */
    Publisher<Void> save(BucketName bucketName, BlobId blobId, InputStream inputStream);

    /**
     * @see #save(BucketName, BlobId, byte[])
     */
    Publisher<Void> save(BucketName bucketName, BlobId blobId, ByteSource content);

    /**
     * @see #save(BucketName, BlobId, byte[])
     *
     * The String is stored as UTF-8.
     */
    default Publisher<Void> save(BucketName bucketName, BlobId blobId, String data) {
        return save(bucketName, blobId, data.getBytes(StandardCharsets.UTF_8));
    }

    /**
     * Remove a Blob based on its BucketName and its BlobId.
     * This operation should be atomic
     *
     * @return a successful Mono if the Blob is deleted or did not exist
     * (either the blob doesn't exist in the bucket or the bucket itself doesn't exist)
     *  otherwise an IOObjectStoreException in its error channel
     */
    Publisher<Void> delete(BucketName bucketName, BlobId blobId);

    /**
     * Remove a bucket based on its BucketName
     *
     * Deleting a bucket is not guaranteed to be atomic nor isolated.
     * Saving or reading blobs concurrently of bucket deletion can lead
     * to an inconsistent state.
     *
     * @return a successful Publisher if the bucket is deleted or did not exist
     *  otherwise an IOObjectStoreException in its error channel
     */
    Publisher<Void> deleteBucket(BucketName bucketName);
}