[
https://issues.apache.org/jira/browse/HADOOP-5438?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12689229#action_12689229
]
Jakob Homan commented on HADOOP-5438:
-------------------------------------
The Java-centric way to do C-style bit packing is with EnumSets
(http://www.jakobhoman.com/2008/08/javas-enumset-fun-for-whole-family.html),
which is future-proof but a bit verbose.
{code}
enum CreateFlag {
OVERWRITE ((short)0x01),
APPEND ((short)0x02);
CreateFlag(short mode) { this.mode = mode; }
CreateFlag() { this.mode = (short)0x01; }
public short getMode() { return mode; }
private short mode;
}
public static createFile(Path p, EnumSet<CreateFlag> flags) {
if(flags.contains(CreateFlag.APPEND))
// blah
}
{code}
We ran into a similar issue with create flags on Zookeeper (ZOOKEEPER-132), and
ended up using them but had to enumerate all the possible values for creating
actual integer flags.
> Merge FileSystem.create and FileSystem.append
> ---------------------------------------------
>
> Key: HADOOP-5438
> URL: https://issues.apache.org/jira/browse/HADOOP-5438
> Project: Hadoop Core
> Issue Type: Improvement
> Reporter: He Yongqiang
>
> Currently, when a user wants to modify a file, the user first calls exists()
> to know if this file is already there. And then uses create() or append()
> according to whether the file exists or not.
> the code looks like:
> {code}
> FSDataOutputStream out_1 = null;
> if (fs.exists(path_1))
> out_1 = fs.append(path_1);
> else
> out_1 = fs.create(path_1);
> {code}
> . On the performace side,It involes two RPCs. On the easy-of-use side, it is
> not very convient in contrast to the traditional open interface.
> It will more complicate if there is a overwrite parameter specified. I donot
> know whether there is a bug about 'overwrite' in 0.19, some times it takes a
> long time for overwrite creates to reture. So i make the write file code with
> overwrite param works like:
> {code}
> boolean exists = fs.exists(name);
> if (overwrite) {
> if (exists)
> fs.delete(name, true);
> this.out = fs.create(name, overwrite, bufferSize, replication,
> blockSize, progress);
> this.currentRowID = 0;
> } else {
> if (!exists)
> this.out = fs.create(name, overwrite, bufferSize,
> replication, blockSize, progress);
> else
> this.out = fs.append(name, bufferSize, progress);
> {code}
> Some code statements there are really redundant and not needed, especialy
> with the delete(). But without deleting first, the overwrite takes a long
> time to reture.
> BTW, i will create another issue about the overwrite problem. If it is not a
> bug at all or a duplicate, someone please close it.
--
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.
