kerneltime commented on code in PR #6385:
URL: https://github.com/apache/ozone/pull/6385#discussion_r1571124162
##########
hadoop-ozone/client/src/main/java/org/apache/hadoop/ozone/client/OzoneBucket.java:
##########
@@ -469,6 +469,30 @@ public OzoneOutputStream createKey(String key, long size,
.createKey(volumeName, name, key, size, replicationConfig,
keyMetadata);
}
+ /**
+ * Overwrite an existing key using optimistic locking. The existingKey must
exist in Ozone to allow
+ * the new key to be created with the same name. Additionally, the existing
Key must not have been
+ * modified since the time it's details were read. This is controlled by the
updateID
+ * field in the existing Key. If the key is replaced or updated the updateID
will change. If the
+ * updateID has changed since the existing Key was read, either the initial
key create will fail,
+ * or the key will fail to commit after the data has been written as the
checks are carried out
+ * both a key open and commit time.
+ *
+ * For now this feature only works on Object Store Buckets. FSO support will
be added a later.
+ *
+ * @param existingKey Name of the key to be created.
+ * @param replicationConfig Replication configuration.
+ * @return OzoneOutputStream to which the data has to be written.
+ * @throws IOException
+ */
+ public OzoneOutputStream overwriteKey(OzoneKeyDetails existingKey,
ReplicationConfig replicationConfig)
Review Comment:
```suggestion
public OzoneOutputStream atomicUpdateKey(OzoneKeyDetails existingKey,
ReplicationConfig replicationConfig)
```
##########
hadoop-ozone/client/src/main/java/org/apache/hadoop/ozone/client/OzoneBucket.java:
##########
@@ -469,6 +469,30 @@ public OzoneOutputStream createKey(String key, long size,
.createKey(volumeName, name, key, size, replicationConfig,
keyMetadata);
}
+ /**
+ * Overwrite an existing key using optimistic locking. The existingKey must
exist in Ozone to allow
+ * the new key to be created with the same name. Additionally, the existing
Key must not have been
+ * modified since the time it's details were read. This is controlled by the
updateID
+ * field in the existing Key. If the key is replaced or updated the updateID
will change. If the
+ * updateID has changed since the existing Key was read, either the initial
key create will fail,
+ * or the key will fail to commit after the data has been written as the
checks are carried out
+ * both a key open and commit time.
+ *
+ * For now this feature only works on Object Store Buckets. FSO support will
be added a later.
+ *
+ * @param existingKey Name of the key to be created.
+ * @param replicationConfig Replication configuration.
+ * @return OzoneOutputStream to which the data has to be written.
+ * @throws IOException
+ */
+ public OzoneOutputStream overwriteKey(OzoneKeyDetails existingKey,
ReplicationConfig replicationConfig)
+ throws IOException {
+ if (this.bucketLayout != BucketLayout.OBJECT_STORE) {
+ throw new IllegalArgumentException("Optimistic locking is only supported
on Object Store Buckets");
Review Comment:
This validation should move into OM to allow older clients to be able to
update keys when OM supports it.
##########
hadoop-ozone/client/src/main/java/org/apache/hadoop/ozone/client/OzoneBucket.java:
##########
@@ -469,6 +469,30 @@ public OzoneOutputStream createKey(String key, long size,
.createKey(volumeName, name, key, size, replicationConfig,
keyMetadata);
}
+ /**
+ * Overwrite an existing key using optimistic locking. The existingKey must
exist in Ozone to allow
+ * the new key to be created with the same name. Additionally, the existing
Key must not have been
+ * modified since the time it's details were read. This is controlled by the
updateID
+ * field in the existing Key. If the key is replaced or updated the updateID
will change. If the
+ * updateID has changed since the existing Key was read, either the initial
key create will fail,
+ * or the key will fail to commit after the data has been written as the
checks are carried out
+ * both a key open and commit time.
+ *
+ * For now this feature only works on Object Store Buckets. FSO support will
be added a later.
Review Comment:
```suggestion
* This API allows to atomically update an existing key. The key read
before invoking this API
* should remain unchanged for this key to be written. This is controlled
by the updateID
* field in the existing Key param. If the key is replaced or updated the
updateID will change. If the
* updateID has changed since the existing Key was read, either the
initial key create will fail,
* or the key will fail to commit after the data has been written as the
checks are carried out
* both a key open and commit time.
*
* For now this feature only works on Object Store Buckets. FSO support
will be added a later.
```
##########
hadoop-ozone/client/src/main/java/org/apache/hadoop/ozone/client/OzoneKey.java:
##########
@@ -70,11 +70,19 @@ public class OzoneKey {
* Constructs OzoneKey from OmKeyInfo.
*
*/
+
+ /**
+ * The update ID of an existing key. This will be null if this OzoneKey
+ * object has not been created from an existing key read from OM, as OM
allocates
+ * the update ID on commit of the key.
+ */
+ private final Long updateID;
Review Comment:
We are leaking internal names into public APIs. For public facing API, I
would model it how google APIs have documented theirs :
https://cloud.google.com/storage/docs/metadata#generation-number
(We do not have the split between metadata only updates vs. whole object.)
For now, I would change this to `generation` and document the guarantees
that an application has around the use of generation. This should apply to the
entire PR, where we use `updateID` which is a more nebulous name.
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