Add new constructors to PackFile to improve a common use case where
callers know the directory, id, and extension, but previously needed to
construct a valid file name (with prefix, '.', etc) to create a
PackFile. Most callers can use the variant that has id as an ObjectId,
but provide an id as String variant too.

Change-Id: I39e4466abe8c9509f5916d5bfe675066570b8585
Signed-off-by: Nasser Grainawi <quic_nasserg@quicinc.com>

If
- pack.waitPreventRacyPack = true (default is false)
- packfile size > pack.minSizePreventRacyPack (default is 100 MB)
wait after a new packfile was written and before it is opened until it
cannot be racy anymore.

If a new packfile is accessed while it's still racy at least the pack's
index will be reread by ObjectDirectory.scanPacksImpl(). Hence it may
save resources to wait one tick of the file system timer to avoid this
reloading. On filesystems with a coarse timestamp resolution it may be
beneficial to skip this wait for small packfiles.

Bug: 546891
Change-Id: I0e8bf3d7677a025edd2e397dd2c9134ba59b1a18
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>

Change-Id: Id924f79c8b2c720297ebc49bf9c5d4ddd6d52547
Signed-off-by: Han-Wen Nienhuys <hanwen@google.com>

The intent with the setCompressionLevel and checkExisting methods (which
are already public) is for callers to be able to call them, but they
can't do that if the class itself is not public.

Change-Id: I014044fec3bfa1d33775500345efd60eb5d45bde

When interleaving reads and writes from an unflushed pack, we forgot to
reset the file pointer back to the end of the file before writing more
new objects. This had at least two unfortunate effects:
  * The pack data was potentially corrupt, since we could overwrite
    previous portions of the file willy-nilly.
  * The CountingOutputStream would report more bytes read than the size
    of the file, which stored the wrong PackedObjectInfo, which would
    cause EOFs during reading.

We already had a test in PackInserterTest which was supposed to catch
bugs like this, by interleaving reads and writes. Unfortunately, it
didn't catch the bug, since as an implementation detail we always read a
full buffer's worth of data from the file when inflating during
readback. If the size of the file was less than the offset of the object
we were reading back plus one buffer (8192 bytes), we would completely
accidentally end up back in the right place in the file.

So, add another test for this case where we read back a small object
positioned before a large object. Before the fix, this test exhibited
exactly the "Unexpected EOF" error reported at crbug.com/gerrit/7668.

Change-Id: I74f08f3d5d9046781d59e5bd7c84916ff8225c3b

CorruptObjectException has a constructor that takes Throwable and
calls initCause with it.  Use that instead of instantiating the
exception and explicitly calling initCause.

Change-Id: I1f2747d6c4cc5249e93401b9787eb4ceb50cb995
Signed-off-by: David Pursehouse <david.pursehouse@gmail.com>

Change-Id: Ieb2f66aef2cab7e2a6d8e35c5f5047da881994dd
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>

So far, in order to get the pack directory it was necessary to resolve
it from the object directory. This resolution is already done when
creating the object directory, so simplify the call by just adding a
getter to the pack directory.

Change-Id: I69e783141dc6739024e8b3d5acc30843edd651a7
Signed-off-by: Hector Caballero <hector.caballero@ericsson.com>

Change-Id: Ib9e7f6439332eaed3d936f895a5271a7d514d3e9

Applications that use ObjectInserters to create lots of individual
objects may prefer to avoid cluttering up the object directory with
loose objects. Add a specialized inserter implementation that produces a
single pack file no matter how many objects. This inserter is loosely
based on the existing DfsInserter implementation, but is simpler since
we don't need to buffer blocks in memory before writing to storage.

An alternative for such applications would be to write out the loose
objects and then repack just those objects later. This operation is not
currently supported with the GC class, which always repacks existing
packs when compacting loose objects. This in turn requires more
CPU-intensive reachability checks and extra I/O to copy objects from old
packs to new packs.

So, the choice was between implementing a new variant of repack, or not
writing loose objects in the first place. The latter approach is likely
less code overall, and avoids unnecessary I/O at runtime.

The current implementation does not yet support newReader() for reading
back objects.

Change-Id: I2074418f4e65853b7113de5eaced3a6b037d1a17