SSH Authentication is quite expensive (~120ms on localhost against
Gerrit with LFS plugin). The SSH authentication typically also sends a
validity time of the returned token, which allows to re-use it for a
certain time, avoiding the expensive authentication on every download
request. This improves checkout times by large factors depending on the
LFS object amount/sizes.

Also make sure that all instances of Gson used by LFS are configured in
the same way.

Change-Id: I422c94c37021b4322789b3829fa0185e25d683f2
Signed-off-by: Markus Duft <markus.duft@ssi-schaefer.com>

Transfer data in chunks of 8k Transferring data byte per byte is slow,
running checkout with CleanFilter on a 2.9MB file takes 20 seconds.
Using a buffer of 8k shrinks this time to 70ms.

Also register the filter commands in a way that the native GIT LFS can
be used alongside with JGit.

Implements auto-discovery of LFS server URL when cloning from a Gerrit
LFS server.

Change-Id: I452a5aa177dcb346d92af08b27c2e35200f246fd
Also-by: Christian Halstrick <christian.halstrick@sap.com>
Signed-off-by: Markus Duft <markus.duft@ssi-schaefer.com>

For now ignore doclint "missing" warnings.

Change-Id: I0e5af7a757f4d92ffeeb113f30576a35414d6781
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>

Change-Id: I0a86ce0e393dfde9bb27f0b29e036e76c856396e
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
Signed-off-by: Chris Aniszczyk <zx@twitter.com>

Bug: 361548
CQ: 6243
Change-Id: I08e1369e142bb19f42a8d7bbb5a7d062cc8533fc
Signed-off-by: Chris Aniszczyk <zx@twitter.com>

Per CQ 3448 this is the initial contribution of the JGit project
to eclipse.org.  It is derived from the historical JGit repository
at commit 3a2dd9921c.

Signed-off-by: Shawn O. Pearce <spearce@spearce.org>