Xodus VFS not able to persist bytes

Question

The problem with the code below is that the VFS does not seem to be able to persist the byte array. As Xodus VFS writes zero byte:

  @Override
  public FileModel put(
      String appId, String namespace, String name, InputStream is) {
    final FileModel[] createdFile = {null};
    final Environment env = manager.getEnvironment(xodusRoot, appId);
    final VirtualFileSystem vfs  = new VirtualFileSystem(env);
    env.executeInTransaction(
        new TransactionalExecutable() {
          @Override
          public void execute(@NotNull final Transaction txn) {
            final File file = vfs.openFile(txn, name, true);;
            try {
              byte[] ba = ByteStreams.toByteArray(is);
              LOG.info("Byte array size: " + ba.length); // Size: 3466
              vfs.writeFile(txn, file).write(ba, 0, ba.length);
            } catch (IOException e) {
              e.printStackTrace();
            }
            long fileSize = vfs.getFileLength(txn, file);
            LOG.info("File Size: " + fileSize); // Size: 0 <----
            createdFile[0] = new FileModel();
            createdFile[0].setDescriptor(file.getDescriptor());
            createdFile[0].setName(name);
            createdFile[0].setCreated(file.getCreated());
            createdFile[0].setModified(file.getLastModified());
          }
        });
    vfs.shutdown();
    return createdFile[0];
  }

And here's the log:

[qtp1007568224-16] WARN jetbrains.exodus.io.FileDataWriter - Can't open directory channel. Log directory fsync won't be performed.
[qtp1007568224-16] WARN jetbrains.exodus.io.FileDataWriter - Can't open directory channel. Log directory fsync won't be performed.
[qtp1007568224-16] INFO jetbrains.exodus.env.EnvironmentImpl - Exodus environment created: \tmp\xodus\master
[qtp1007568224-16] WARN jetbrains.exodus.io.FileDataWriter - Can't open directory channel. Log directory fsync won't be performed.
[qtp1007568224-16] INFO jetbrains.exodus.env.EnvironmentImpl - Exodus environment created: \tmp\xodus\ab5b92099ad443259b4deaf8df6facc4
[qtp1007568224-16] INFO com.backend.repository.jee.JeeXodusVFSRepository - Byte array size: 3466
[qtp1007568224-16] INFO com.backend.repository.jee.JeeXodusVFSRepository - File Size: 0
[qtp1007568224-16] INFO com.backend.resource.jee.JeeFileServerResource - File size=3466; File.created=1575274836678; File.name="index.html"; File.modified=1575274836678; File.etag=<null>; File.descriptor=261; File.url=<null>

What if you replace `executeInTransaction` by `executeInExclusiveTransaction`? — Vyacheslav Lukianov, Dec 03 '19 at 13:24
@VyacheslavLukianov same result, size of `getFileLength` is zero — quarks, Dec 03 '19 at 13:29
What would be the possible reason that the file size is `0`? Is there a bug in the `writeFile` method? — quarks, Dec 03 '19 at 13:36

score 1 · Accepted Answer · answered Dec 03 '19 at 13:42

1

The method vfs.writeFile(txn, file) returns an OutputStream instance that should be closed to save written data.

answered Dec 03 '19 at 13:42

Vyacheslav Lukianov

1,913
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12

The problem with the VFS also is that when you try to override a file, like `File file = vfs.openFile(txn, name, true);` it appends the stream and corrupts the file. – quarks Dec 03 '19 at 16:18
It seems if the new bytes to write into the filed is shorter the other bytes that are part of the file still exists. – quarks Dec 03 '19 at 16:20
And in order to work around this ` `txn -> { vfs.deleteFile(txn, name); File file = vfs.openFile(txn, name, true);}` but I feel that this is quite not the correct way to do it. – quarks Dec 03 '19 at 16:42
1

It shouldn't append. It doesn't clear the content of the file before writing, it writes above existing content from the beginning – Vyacheslav Lukianov Dec 03 '19 at 16:53
Ah yes, I mean it writes but does not remove existing bytes, what is the proper way to achieve normal override? – quarks Dec 03 '19 at 17:08

Xodus VFS not able to persist bytes

1 Answers1