Instead of using hard-coded HTTP status codes, use the enums
which makes it a bit easier to see what's expected.

Change-Id: I2da5d25632f374b8625d64da4df70d1c9c406bb1
Signed-off-by: David Pursehouse <david.pursehouse@gmail.com>

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

Change-Id: I495f0b60b7128fff27502641e6a5d05f888d4e8a
Signed-off-by: David Pursehouse <david.pursehouse@gmail.com>

According to the specification [1], the error response body must
include the error message in json format.

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

Change-Id: I79e7a841d230fdedefa53b9c6d2d477e81e1f9e6
Signed-off-by: David Pursehouse <david.pursehouse@gmail.com>

According to the specification [1], the error response status code
should be 422 when there is a validation error with one or more of
the objects in the request

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

Change-Id: Id03fe00a2109b896d9a154228a14a33bce5accc3
Signed-off-by: David Pursehouse <david.pursehouse@gmail.com>

The FileLfsRepository.out member could have been accessed from multiple
threads which would corrupt the content.

Don't store the AtomicObjectOutputStream in the FileLfsRepository.out but
move it to the ObjectUploadListener which is instantiated per-request.

Add a parallel upload test.

Change-Id: I62298630e99c46b500d376843ffcde934436215b
Signed-off-by: Saša Živkov <sasa.zivkov@sap.com>
Signed-off-by: Matthias Sohn <matthias.sohn@sap.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>