It is not obvious why this return statement is needed. Clarify with a
comment that otherwise endless loop may show up when recent versions
of Jetty are used.

Change-Id: I8e5d4de51869fb1179bf599bfb81bcd7d745874b
Signed-off-by: David Ostrovsky <david@ostrovsky.org>

Current code violates the ServletOutputStream contract. For every
out.isReady() == true either write or close of that ServletOutputStream
should be called.

See also this issue upstream for more context: [1].

[1] https://github.com/eclipse/jetty.project/issues/2911

Change-Id: Ied575f3603a6be0d2dafc6c3329d685fc212c7a3
Signed-off-by: David Ostrovsky <david@ostrovsky.org>
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>

When buffer was written not only call AsyncContext#complete() but also
return from the ObjectDownloadListener#onWritePossible(). This avoids
endless loop after upgrading from Jetty 9.3.x to 9.4.x lines.

In Jetty example implementation:[1] the return statemnt is also used:

  // If we are at EOF then complete
  if (len < 0)
  {
    async.complete();
    return;
  }

See also this issue upstream: [2].

[1] https://webtide.com/servlet-3-1-async-io-and-jetty
[2] https://github.com/eclipse/jetty.project/issues/2911

Change-Id: Iac73fb25e67d40228a378a8e34103f1d28b72a76
Signed-off-by: David Ostrovsky <david@ostrovsky.org>

Change-Id: I0c52536ebeeb8e71d95c6420f6db7055ff082dfa
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>

The same was already done for ObjectUploadListener in I5b0fb1220.

Change-Id: Ie8a79f715fe69bed9331962fb478f7e35acf8680
Signed-off-by: David Pursehouse <david.pursehouse@gmail.com>

Change-Id: Ib7b73d7d37574682bb58f969822c842e4e579233
Signed-off-by: David Pursehouse <david.pursehouse@gmail.com>

Implement LfsProtocolServlet handling the "Git LFS v1 Batch API"
protocol [1]. Add a simple file system based LFS content store and the
debug-lfs-store command to simplify testing.

Introduce a LargeFileRepository interface to enable additional storage
implementation while reusing the same protocol implementation.

At the client side we have to configure the lfs.url, specify that
we use the batch API and we don't use authentication:

  [lfs]
	  url = http://host:port/lfs
	  batch = true
  [lfs "http://host:port/lfs"]
	  access = none

the git-lfs client appends the "objects/batch" to the lfs.url.

Hard code an Authorization header in the FileLfsRepository.getAction
because then git-lfs client will skip asking for credentials. It will
just forward the Authorization header from the response to the
download/upload request.

The FileLfsServlet supports file content storage for "Large File
Storage" (LFS) server as defined by the Github LFS API [2].

- upload and download of large files is probably network bound hence use
  an asynchronous servlet for good scalability
- simple object storage in file system with 2 level fan-out
- use LockFile to protect writing large objects against multiple
  concurrent uploads of the same object
- to prevent corrupt uploads the uploaded file is rejected if its hash
  doesn't match id given in URL

The debug-lfs-store command is used to run the LfsProtocolServlet and,
optionally, the FileLfsServlet which makes it easier to setup a
local test server.

[1]
https://github.com/github/git-lfs/blob/master/docs/api/http-v1-batch.md
[2] https://github.com/github/git-lfs/tree/master/docs/api

Bug: 472961
Change-Id: I7378da5575159d2195138d799704880c5c82d5f3
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
Signed-off-by: Sasa Zivkov <sasa.zivkov@sap.com>