Change-Id: Ib6ee3a2874a7e2240aa68f4ac32d00c4d1fab5ae
Signed-off-by: Chris Aniszczyk <zx@twitter.com>

This breaks all existing callers once. Applications are not supposed
to build against the internal storage API unless they can accept API
churn and make necessary updates as versions change.

Change-Id: I2ab1327c202ef2003565e1b0770a583970e432e9

Change-Id: I83ca25fb569c0dbc36eb374d5437fcf2b65a6f68

Change-Id: I1df945011f8e5f03959b693d3564fe357e707f91

Change-Id: I763590a45d75f00a09097ab6f89581a3bbd3c797

By moving the logic that parses a pack stream from the network (or
a bundle) into a type that can be constructed by an ObjectInserter,
repository implementations have a chance to inject their own logic
for storing object data received into the destination repository.

The API isn't completely generic yet, there are still quite a few
assumptions that the PackParser subclass is storing the data onto
the local filesystem as a single file.  But its about the simplest
split of IndexPack I can come up with without completely ripping
the code apart.

Change-Id: I5b167c9cc6d7a7c56d0197c62c0fd0036a83ec6c
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Chris Aniszczyk <caniszczyk@gmail.com>

Eclipse has some problem re-running single JUnit tests if
the tests are in Junit 3 format, but the JUnit 4 launcher
is used. This was quite unnecessary and the move was not
completed. We still have no JUnit4 test.

This completes the extermination of JUnit3. Most of the
work was global searce/replace using regular expression,
followed by numerous invocarions of quick-fix and organize
imports and verification that we had the same number of
tests before and after.

- Annotations were introduced.
- All references to JUnit3 classes removed
- Half-good replacement for getting the test name. This was
  needed to make the TestRngs work. The initialization of
  TestRngs was also made lazily since we can not longer find
  out the test name in runtime in the @Before methods.
- Renamed test classes to end with Test, with the exception
  of TestTranslateBundle, which fails from Maven
- Moved JGitTestUtil to the junit support bundle

Change-Id: Iddcd3da6ca927a7be773a9c63ebf8bb2147e2d13
Signed-off-by: Robin Rosenberg <robin.rosenberg@dewire.com>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>

Projects like org.eclipse.mdt contain large XML files about 6 MiB
in size.  So does the Android project platform/frameworks/base.
Doing a clone of either project with JGit takes forever to checkout
the files into the working directory, because delta decompression
tends to be very expensive as we need to constantly reposition the
base stream for each copy instruction.  This can be made worse by
a very bad ordering of offsets, possibly due to an XML editor that
doesn't preserve the order of elements in the file very well.

Increasing the threshold to the same limit PackWriter uses when
doing delta compression (50 MiB) permits a default configured
JGit to decompress these XML file objects using the faster
random-access arrays, rather than re-seeking through an inflate
stream, significantly reducing checkout time after a clone.

Since this new limit may be dangerously close to the JVM maximum
heap size, every allocation attempt is now wrapped in a try/catch
so that JGit can degrade by switching to the large object stream
mode when the allocation is refused.  It will run slower, but the
operation will still complete.

The large stream mode will run very well for big objects that aren't
delta compressed, and is acceptable for delta compressed objects that
are using only forward referencing copy instructions.  Copies using
prior offsets are still going to be horrible, and there is nothing
we can do about it except increase core.streamFileThreshold.

We might in the future want to consider changing the way the delta
generators work in JGit and native C Git to avoid prior offsets once
an object reaches a certain size, even if that causes the delta
instruction stream to be slightly larger.  Unfortunately native
C Git won't want to do that until its also able to stream objects
rather than malloc them as contiguous blocks.

Change-Id: Ief7a3896afce15073e80d3691bed90c6a3897307
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Chris Aniszczyk <caniszczyk@gmail.com>

Use 3 different types of LargeObjectException for the 3 major ways
that we can fail to load an object.  For each of these use a unique
string translation which describes the root cause better than just
the ObjectId.name() does.

Change-Id: I810c98d5691b74af9fc6cbd46fc9879e35a7bdca
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>

Because we are using the large stream size, we have to be
above the STREAM_THRESHOLD constant, which I just increased.

Change-Id: I6f10ec8558d9f751d4b547fcae05af94f1c8866b
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>

We default this to 1 MiB for now, but we allow users to modify
it through the Repository's configuration file to be a different
value.  A new repository listener is used to identify when the
setting has been updated and trigger a reconfiguration of any
active ObjectReaders.

To prevent a horrible explosion we cap core.streamFileThreshold
at no more than 1/4 of the maximum JVM heap size.  We do this
because we need at least 2 byte arrays equal in size to the
stream threshold for the worst case delta inflation scenario,
and our host application probably also needs some amount of the
heap for their working set size.

Change-Id: I103b3a541dc970bbf1a6d92917a12c5a1ee34d6c
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>

Very large delta instruction streams, or deltas which use very large
base objects, are now streamed through as large objects rather than
being inflated into a byte array.

This isn't the most efficient way to access delta encoded content, as
we may need to rewind and reprocess the base object when there was a
block moved within the file, but it will at least prevent the JVM from
having its heap explode.

When streaming a delta we have an inflater open for each level in the
delta chain, to inflate the instruction set of the delta, as well as
an inflater for the base level object.  The base object is buffered,
as is the top level delta requested by the application, but we do not
buffer the intermediate delta streams.  This keeps memory usage lower,
so its closer to 1024 bytes per level in the chain, without having an
adverse impact on raw throughput as the top-level buffer gets pushed
down to the lowest stream that has the next region.

Delta instructions transparently collapse here, if the top level does
not copy a region from its base, the base won't materialize that part
from its own base, etc.  This allows us to avoid copying around a lot
of segments which have been deleted from the final version.

Change-Id: I724d45245cebb4bad2deeae7b896fc55b2dd49b3
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>

Similar to the loose object support, whole packed objects can
now be streamed back to the caller.  The streaming is less
efficient as we copy the data from the cached window array
into the InflaterInputStream's internal buffer, then inflate
it there before returning to the application.

Like with unpacked objects, there is plenty of room for some
optimization, especially for the copyTo method, where we don't
necessarily need so much buffering to exist.

Change-Id: Ie23be81289e37e24b91d17b0891e47b9da988008
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>