Link to an example type constant.

Change-Id: I214ab834fa02901a38e6048a94a5224b30c5d93f
Signed-off-by: Robin Stocker <robin@nibor.org>

Similar to what we did on Repository, the openObject method
already implied we wanted to open an object, given its main
argument was of type AnyObjectId.  Simplify the method name
to just the action, has or open.

Change-Id: If055e5e0d8de0e2424c18a773f6d2bc2f66054f4
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>

We drop the "Object" suffix, because its pretty clear here that
we want to open an object, given that we pass in AnyObjectId as
the main parameter.  We also fix the calling convention to throw
a MissingObjectException or IncorrectObjectTypeException, so that
callers don't have to do this error checking themselves.

Change-Id: I72c43353cea8372278b032f5086d52082c1eee39
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>

The WindowCache is an implementation detail of PackFile and how its
used by ObjectDirectory.  Lets start to hide it and replace the public
API with a more generic concept, ObjectReader.

Because PackedObjectLoader is also considered a private detail of
PackFile, we have to make PackWriter temporarily dependent upon the
WindowCursor and thus FileRepository and ObjectDirectory in order to
just start the refactoring.  In later changes we will clean up the
APIs more, exposing sufficient support to PackWriter without needing
the file specific implementation details.

Change-Id: I676be12b57f3534f1285854ee5de1aa483895398
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>

Not every object storage system will have the concept of alternate
object databases to search, and even if they do, they may not have
the notion of fast-access / slow-access split like we do within
the ObjectDirectory code for pack files and loose objects.

Push all of that down below the generic API so that it is a hidden
detail of the ObjectDirectory and its related supporting classes.

Change-Id: I54bc1ca5ff2ac94dfffad1f9a9dad7af202b9523
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>

The ObjectInserter API permits ObjectDatabase implementations to
control their own object insertion behavior, rather than forcing
it to always be a new loose file created in the local filesystem.
Inserted objects can also be queued and written asynchronously to
the main application, such as by appending into a pack file that
is later closed and added to the repository.

This change also starts to open the door to non-file based object
storage, such as an in-memory HashMap for unit testing, or a more
complex system built on top of a distributed hash table.

To help existing application code port to the newer interface we
are keeping ObjectWriter as a delegation wrapper to the new API.
Each ObjectWriter instances holds a reference to an ObjectInserter
for the Repository's top-level ObjectDatabase, and it flushes and
releases that instance on each object processed.

Change-Id: I413224fb95563e7330c82748deb0aada4e0d6ace
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>

On Windows systems, file system lookup is a slow operation, so
checking each object if it exists during indexing (after receiving
the pack) could take a siginificant time. This patch introduces
CachedObjectDirectory that pre-caches lookup results.

Bug: 300397
Change-Id: I471b93f9bb3ee173eb37cae1d75e9e4eb49985e7
Signed-off-by: Constantine Plotnikov <constantine.plotnikov@gmail.com>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>

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>