Shawn Pearce [Thu, 9 May 2013 00:34:47 +0000 (17:34 -0700)]
Fix hardcoded use of target/trash in LocalDiskRepositoryTestCase
`pwd`/target is only valid in Maven Reactor builds where Maven
has moved into the project directory and created a target for
the build output. Most other build systems do not use "target"
and may not even perform a directory change between test suites.
Rewrite LocalDiskRepositoryTestCase's temporary directory code
to use the system specified location and create new unique names.
This prevents fixes between concurrently running tests and allows
the caller to specify the root using java.io.tmpdir.
Update the surefire command lines to use target within each project as
the system temporary directory during unit testing, preventing JGit's
own test suite from writing to /tmp or somewhere like C:\tmp.
Dave Borowitz [Fri, 3 May 2013 18:22:25 +0000 (11:22 -0700)]
Remove unused repository field from RevWalk
The comment about legacy Tag and Object types no longer applies,
though prior to Idb273d5a92849b42935ac14eed73b796b80aad50 the field
was still being used by RewriteTreeFilter.
Dave Borowitz [Fri, 3 May 2013 18:18:53 +0000 (11:18 -0700)]
Require a DiffConfig when creating a FollowFilter
The various rename detection options are an inherent part of the
filter, similar to the path being followed.
This fixes a potential NPE when a RevWalk with a FollowFilter is
created without a Repository, since the old code path tried to get
the DiffConfig from the RevWalk's possibly-missing repository.
Matthias Sohn [Mon, 11 Mar 2013 23:40:34 +0000 (00:40 +0100)]
Add optional feature to install Java 7 support
Change-Id: I15cfd91857830d69abbe729be3e237fc9cd4fca0 Signed-off-by: Robin Rosenberg <robin.rosenberg@dewire.com> Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
Robin Rosenberg [Mon, 4 Feb 2013 00:10:26 +0000 (01:10 +0100)]
Extend the FS class for Java7
The most important difference is that in Java7 we have symbolic links
and for most operations in the work tree we want to operate on the link
itself rather than the link target, which the old File methods generally
do.
We also add support for the hidden attribute, which only makes sense
on Windows and exists, just since there are claims that Files.exists
is faster the File.exists.
A new bundle is only activated when run with a Java7 execution
environment. It is implemented as a fragment.
Tycho currently has no way to conditionally include optional features
based on the java version used to run the build, this means with this
change the jgit packaging build always needs to be run using java 7.
Change-Id: I3d6580d6fa7b22f60d7e54ab236898ed44954ffd Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
Robin Stocker [Sat, 27 Apr 2013 14:14:46 +0000 (16:14 +0200)]
Only fetch tags that do not exist locally with auto-follow
This corresponds to what C Git does, quoting from the fetch man page:
This is done by first fetching from the remote using the given
<refspec>s, and if the repository has objects that are pointed by
remote tags that it does not yet have, then fetch those missing tags.
Before, JGit would also fetch tags that exist locally but point to a
different object, resulting in REJECTED results for these.
Also add some test cases to cover more cases.
Bug: 388095
Change-Id: Ib03d2d82e9c4b60179d626cfd5174be1da6388b2 Also-by: Stefan Lay <stefan.lay@sap.com>
Robin Stocker [Fri, 12 Apr 2013 12:21:02 +0000 (14:21 +0200)]
Abort before delete in FileUtils.delete EMPTY_DIRECTORIES_ONLY|RECURSIVE
Depending on the order in which items are traversed for RECURSIVE, an
empty directory may come first before detecting that there is a file and
aborting.
This fixes it by traversing files first.
Bug: 405558
Change-Id: I638b7da58e33ffeb0fee172b96f4c823943d29e9 Signed-off-by: Robin Rosenberg <robin.rosenberg@dewire.com> Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
Alex Blewitt [Sat, 27 Apr 2013 10:34:57 +0000 (11:34 +0100)]
Allow deletions to occur when there is no HEAD
If the HEAD is not present in a repository, then there is a
NullPointerException thrown in the delete code. Since this only
exists to verify if the deletion is not the HEAD reference, then
skip this check if the HEAD cannot be found.
Bug: 406722
Change-Id: I882497202d986096513a4d791cd07fa935a3f9e4 Signed-off-by: Alex Blewitt <alex.blewitt@gmail.com>
Jonathan Nieder [Thu, 25 Apr 2013 21:20:54 +0000 (14:20 -0700)]
archive: Release resources before returning
The only caller exits immediately after calling execute() so this
shouldn't make a difference, but it's good practice and should make it
easier to expose the functionality in a public API later.
Jonathan Nieder [Fri, 26 Apr 2013 17:16:09 +0000 (10:16 -0700)]
Remove unused logger from RecursiveMerger
JGit doesn't currently use java.util.logging.Logger. Remove this
never-used Logger introduced in ab99b78ca08a (Implement recursive
merge strategy, 2013-02-21) to make that easier to see.
Revert "Add tests for FileUtils.delete and EMPTY_DIREECTORIES_ONLY"
This reverts commit 7aa54967a26cb027fe390ad1c624ebb30f9ac6d5.
The unit test dependend upon the specific order of names that
listFiles() returned members in. The order is completely undefined
and may differ even on different versions of Linux based systems.
A proper unit test for this code would have considered both cases,
where the deletion function was able to remove an empty subdirectory,
or fail to remove a subdirectory because a file was still present
within. This is not such a test.
Robin Stocker [Thu, 21 Mar 2013 00:39:04 +0000 (01:39 +0100)]
IndexDiff: Provide stage state for conflicting entries
Adds a new method getConflictingStageStates() which returns a
Map<String, StageState> (path to stage state). StageState is an enum for
all possible stage combinations (BOTH_DELETED, ADDED_BY_US, ...).
This can be used to implement the conflict text for unmerged paths in
output of "git status" or in EGit for decorations/hints.
Bug: 403697
Change-Id: Ib461640a43111b7df4a0debe92ff69b82171329c Signed-off-by: Chris Aniszczyk <zx@twitter.com>
Matthias Sohn [Thu, 18 Apr 2013 20:35:37 +0000 (22:35 +0200)]
Do not export package org.eclipse.jgit from jgit tests
Commit 3344b93c erroneously exported the package org.eclipse.jgit.lib
from the org.eclipse.jgit.test bundle which made this a split package
since the bundle org.eclipse.jgit exports the same package.
Split packages are evil in general and most probably caused the build
cycle errors observed recently when importing the jgit projects in
Eclipse [1].
Rescale "Compressing objects" progress meter by size
Instead of counting objects processed, count number of bytes added
into the window. This should rescale the progress meter so that 30%
complete means 30% of the total uncompressed content size has been
inflated and fed into the window.
In theory the progress meter should be more accurate about its
percentage complete/remaining fraction than with objects. When
counting objects small objects move the progress meter more rapidly
than large objects, but demand a smaller amount of work than large
objects being compressed.
Instead of assuming all objects cost the same amount of time to
delta compress, aggregate the byte size of objects in the list
and partition threads with roughly equal total bytes.
Before splitting the list select the N largest paths and assign
each one to its own thread. This allows threads to get through the
worst cases in parallel before attempting smaller paths that are
more likely to be splittable.
By running the largest path buckets first on each thread the likely
slowest part of compression is done early, while progress is still
reporting a low percentage. This gives users a better impression of
how fast the phase will run. On very complex inputs the slow part
is more likely to happen first, making a user realize its time to
go grab lunch, or even run it overnight.
If the worst sections are earlier, memory overruns may show up
earlier, giving the user a chance to correct the configuration and
try again before wasting large amounts of time. It also makes it
less likely the delta compression phase reaches 92% in 30 minutes
and then crawls for 10 hours through the remaining 8%.
By excluding objects the compactor can avoid storing objects that
are already well packed in the base GC packs, or any other pack
not being replaced by the current compaction operation.
For deltas the base object is still included even if the base exists
in another exclusion set. This favors keeping deltas for recent
history, to support faster fetch operations for clients.
Matthias Sohn [Mon, 25 Mar 2013 02:39:58 +0000 (03:39 +0100)]
Make recursive merge strategy the default merge strategy
Use recursive merge as the default strategy since it can successfully
merge more cases than the resolve strategy can. This is also the default
in native Git.
Change-Id: I38fd522edb2791f15d83e99038185edb09fed8e1 Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
Update PackBitmapIndexRemapper to handle mappings not in the new pack.
Previously, the code assumed all commits in the old pack would also
be present in the new pack. This assumption caused an
ArrayIndexOutOfBoundsException during remapping of ids. Fix the
iterator to only return entries that may be remapped. Furthermore,
update getBitmap() to return null if commit does not exist in the
new pack.
* changes:
Always attempt delta compression when reuseDeltas is false
Avoid TemporaryBuffer.Heap on very small deltas
Correct distribution of allowed delta size along chain length
Split remaining delta work on path boundaries
Replace DeltaWindow array with circularly linked list
Micro-optimize copy instructions in DeltaEncoder
Micro-optimize DeltaWindow primary loop
Micro-optimize DeltaWindow maxMemory test to be != 0
Mark DeltaWindowEntry methods final
Always attempt delta compression when reuseDeltas is false
If reuseObjects=true but reuseDeltas=false the caller wants attempt
a delta for every object in the input list. Test for reuseDeltas
to ensure every object passes through the searchInWindow() method.
If no delta is possible for an object and it will be stored whole
(non-delta format), PackWriter may still reuse its content from any
source pack. This avoids an inflate()-deflate() cycle to recompress
the object contents.
TemporaryBuffer is great when the output size is not known, but must
be bound by a relatively large upper limit that fits in memory, e.g.
64 KiB or 20 MiB. The buffer gracefully supports growing storage by
allocating 8 KiB blocks and storing them in an ArrayList.
In a Git repository many deltas are less than 8 KiB. Typical tree
objects are well below this threshold, and their deltas must be
encoded even smaller.
For these much smaller cases avoid the 8 KiB minimum allocation used
by TemporaryBuffer. Instead allocate a very small OutputStream
writing to an array that is sized at the limit.
Correct distribution of allowed delta size along chain length
Nicolas Pitre discovered a very simple rule for selecting between two
different delta base candidates:
- if based whole object, must be <= 50% of target
- if at end of a chain, must be <= 1/depth * 50% of target
The rule penalizes deltas near the end of the chain, requiring them to
be very small in order to be kept by the packer. This favors deltas
that are based on a shorter chain, where the read-time unpack cost is
much lower. Fewer bytes need to be consulted from the source pack
file, and less copying is required in memory to rebuild the object.
Junio Hamano explained Nico's rule to me today, and this commit fixes
DeltaWindow to implement it as described.
When no base has been chosen the computation is simply the statements
denoted above. However once a base with depth of 9 has been chosen
(e.g. when pack.depth is limited to 10), a non-delta source may
create a new delta that is up to 10x larger than the already selected
base. This reflects the intent of Nico's size distribution rule no
matter what order objects are visited in the DeltaWindow.
With this patch and my other patches applied, repacking JGit with:
CGit (all) 5,711,735 bytes; real 0m13.942s user 0m47.722s [1]
JGit heads 5,718,295 bytes; real 0m11.880s user 0m38.177s [2]
rest 9,809 bytes
The improved JGit result for the head pack is only 6.4 KiB larger than
CGit's resulting pack. This patch allowed JGit to find an additional
39.7 KiB worth of space savings. JGit now also often runs 2s faster
than CGit, despite also creating bitmaps and pruning objects after the
head pack creation.
[1] time git repack -a -d -F --window=250 --depth=50
[2] time java -Xmx128m -jar jgit debug-gc
When an idle thread tries to steal work from a sibling's remaining
toSearch queue, always try to split along a path boundary. This
avoids missing delta opportunities in the current window of the
thread whose work is being taken.
The search order is reversed to walk further down the chain from
current position, avoiding the risk of splitting the list within
the path the thread is currently processing.
When selecting which thread to split from use an accurate estimate
of the size to be taken. This avoids selecting a thread that has
only one path remaining but may contain more pending entries than
another thread with several paths remaining.
As there is now a race condition where the straggling thread can
start the next path before the split can finish, the stealWork()
loop spins until it is able to acquire a split or there is only
one path remaining in the siblings.
PackWriter generally chooses the order for objects when it builds the
object lists. This ordering already depends on history information to
guide placing more recent objects first and historical objects last.
Allow PackWriter to make the basic ordering decisions, instead of
trying to override them. The old approach of sorting the list caused
DfsReader to override any ordering change PackWriter might have tried
to make when repacking a repository.
This now better matches with WindowCursor's implementation, where
PackWriter solely determines the object ordering.
Replace DeltaWindow array with circularly linked list
Typical window sizes are 10 and 250 (although others are accepted).
In either case the pointer overhead of 1 pointer in an array or
2 pointers for a double linked list is trivial. A doubly linked
list as used here for window=250 is only another 1024 bytes on a
32 bit machine, or 2048 bytes on a 64 bit machine.
The critical search loops scan through the array in either the
previous direction or the next direction until the cycle is finished,
or some other scan abort condition is reached. Loading the next
object's pointer from a field in the current object avoids the
branch required to test for wrapping around the edge of the array.
It also saves the array bounds check on each access.
When a delta is chosen the window is shuffled to hoist the currently
selected base as an earlier candidate for the next object. Moving
the window entry is easier in a double-linked list than sliding a
group of array entries.
The copy instruction formatter should not to compute the shifts and
masks twice. Instead compute them once and assume there is a register
available to store the temporary "b" for compare with 0.
javac and the JIT are more likely to understand a boolean being
used as a branch conditional than comparing int against 0 and 1.
Rewrite NEXT_RES and NEXT_SRC constants to be booleans so the
code is clarified for the JIT.
Micro-optimize DeltaWindow maxMemory test to be != 0
Instead of using a compare-with-0 use a does not equal 0.
javac bytecode has a special instruction for this, as it
is very common in software. We can assume the JIT knows
how to efficiently translate the opcode to machine code,
and processors can do != 0 very quickly.
* changes:
Increase PackOutputStream copy buffer to 64 KiB
Tighten object header writing in PackOutuptStream
Skip main thread test in ThreadSafeProgressMonitor
Declare members of PackOutputStream final
Always allocate the PackOutputStream copyBuffer
Disable CRC32 computation when no PackIndex will be created
Steal work from delta threads to rebalance CPU load
Most objects are written as OFS_DELTA with the base in the pack,
that is why this case comes first in writeHeader(). Rewrite the
condition to always examine this first and cache the PackWriter's
formatting flag for use of OFS_DELTA headers, in modern Git networks
this is true more often then it it is false.
Assume the cost of write() is high, especially due to entering the
MessageDigest to update the pack footer SHA-1 computation. Combine
the OFS_DELTA information as part of the header buffer so that the
entire burst is a single write call, rather than two relatively
small ones. Most OFS_DELTA headers are <= 6 bytes, so this rewrite
tranforms 2 writes of 3 bytes each into 1 write of ~6 bytes.
Try to simplify the objectHeader code to reduce branches and use
more local registers. This shouldn't really be necessary if the
compiler is well optimized, but it isn't very hard to clarify data
usage to either javac or the JIT, which may make it easier for the
JIT to produce better machine code for this method.
Skip main thread test in ThreadSafeProgressMonitor
update(int) is only invoked from a worker thread, in JGit's case
this is DeltaTask. The Javadoc of TSPM suggests update should only
ever be used by a worker thread.
Skip the main thread check, saving some cycles on each run of the
progress monitor.
These methods cannot be sanely overridden anywhere. Most methods
are package visible only, or are private. A few public methods do
exist but there is no useful way to override them since creation
of PackOutputStream is managed by PackWriter and cannot be delegated.
The getCopyBuffer() is almost always used during output. All known
implementations of ObjectReuseAsIs rely on the buffer to be present,
and the only sane way to get good performance from PackWriter is to
reuse objects during packing.
Avoid a branch and test when obtaining this buffer by making sure
it is always populated.
Disable CRC32 computation when no PackIndex will be created
If a server is streaming 3GiB worth of pack data to a client there
is no reason to compute the CRC32 checksum on the objects. The
CRC32 code computed by PackWriter is used only in the new index
created by writeIndex(), which is never invoked for the native Git
network protocols.
Object reuse may still compute its own CRC32 to verify the data
being copied from an existing pack has not been corrupted. This
check is done by the ObjectReader that implements ObjectReuseAsIs
and has no relationship to the CRC32 being skipped during output.
Steal work from delta threads to rebalance CPU load
If the configuration wants to run 4 threads the delta search work
is initially split somewhat evenly across the 4 threads. During
execution some threads will finish early due to the work not being
split fairly, as the initial partitions were based on object count
and not cost to inflate or size of DeltaIndex.
When a thread finishes early it now tries to take 50% of the work
remaining on a sibling thread, and executes that before exiting.
This repeats as each thread completes until a thread has only 1
object remaining.
Repacking Blink, Chromium's new fork of WebKit (2.2M objects 3.9G):
Matthias Sohn [Mon, 8 Apr 2013 21:25:01 +0000 (17:25 -0400)]
Merge changes I8445070d,I38f10d62,I2af0bf68
* changes:
Fix plugin provider names to conform with release train requirement
Add missing @since tags for new API methods
DfsReaderOptions are options for a DFS stored repository
Support cutting existing delta chains longer than the max depth
Some packs built by JGit have incredibly long delta chains due to a
long standing bug in PackWriter. Google has packs created by JGit's
DfsGarbageCollector with chains of 6000 objects long, or more.
Inflating objects at the end of this 6000 long chain is impossible
to complete within a reasonable time bound. It could take a beefy
system hours to perform even using the heavily optimized native C
implementation of Git, let alone with JGit.
Enable pack.cutDeltaChains to be set in a configuration file to
permit the PackWriter to determine the length of each delta chain
and clip the chain at arbitrary points to fit within pack.depth.
Delta chain cycles are still possible, but no attempt is made to
detect them. A trivial chain of A->B->A will iterate for the full
pack.depth configured limit (e.g. 50) and then pick an object to
store as non-delta.
When cutting chains the object list is walked in reverse to try
and take advantage of existing chain computations. The assumption
here is most deltas are near the end of the list, and their bases
are near the front of the list. Going up from the tail attempts to
reuse chainLength computations by relying on the memoized value in
the delta base.
The chainLength field in ObjectToPack is overloaded into the depth
field normally used by DeltaWindow. This is acceptable because the
chain cut happens before delta search, and the chainLength is reset
to 0 if delta search will follow.
This switch is called mostly for OBJ_TREE and OBJ_BLOB types, which
typically make up 66% of the objects in a repository. Simplify the
test for these common types by testing for the one bit they have in
common and returning early.
Object type 5 is currently undefined. In the old code it would hit
the default and return true. In the new code it will match the early
case and also return true. In either implementation 5 should never show
up as it is not a valid type known to Git.
Object type 6 OFS_DELTA is not permitted to be supplied here.
Object type 7 REF_DELTA is not permitted to be supplied here.
Now that WANT_WRITE is gone renumber the flags to move the unused
bit next to the type. Recluster AS_IS and DELTA_ATTEMPTED to be
next to each other since these bits are tested as a pair.
Free up the WANT_WRITE flag in ObjectToPack by switching the test
to use the special offset value of 1. The Git pack file format
calls for the first 4 bytes to be 'PACK', which means any object
must start at an offset >= 4. Current versions require another 8
bytes in the header, placing the first object at offset = 12.
So offset = 1 is an invalid location for an object, and can be
used as a marker signal to indicate the writing loop has tried
to write the object, but recursed into the base first. When an
object is visited with offset == 1 it means there is a cycle in
the delta base path, and the cycle must be broken.
Garbage is randomly ordered and unlikely to delta compress against
other garbage. Disable delta compression allowing objects to switch
to whole form when moving to the garbage pack.
Because the garbage is not well compressed assume deltas were not
attempted during a normal GC cycle.
Override the reuse settings, garbage that can be reused should be
reused as-is into the garbage pack rather than switching something
like the compression level during a GC. It is intended that garbage
will eventually be removed from the repository so expending CPU
time on a compression switch is not worthwhile.
This implementation has been proven to deadlock in production server
loads. Google has been running with it disabled for a quite a while,
as the bugs have been difficult to identify and fix.
Instead of suggesting it works and is useful, drop the code. JGit
should not advertise support for functionality that is known to
be broken.
In a few of the places where read-ahead was enabled by DfsReader
there is more information about what blocks should be loaded when.
During object representation selection, or size lookup, or sending
object as-is to a PackWriter, or sending an entire pack as-is the
reader knows exactly which blocks are required in the cache, and it
also can compute when those will be needed. The broken read-ahead
code was stupid and just read a fixed amount ahead of the current
offset, which can waste IOs if more precise data was available.
DFS systems are usually slow to respond so read-ahead is still
a desired feature, but it needs to be rebuilt from scratch and
make better use of the offset information.
Rewrite this complicated logic to examine each pack file exactly
once. This reduces thrashing when there are many large pack files
present and the reader needs to locate each object's header.
The intermediate temporary list is now smaller, it is bounded to
the same length as the input object list. In the prior version of
this code the list contained one entry for every representation of
every object being packed.
Only one representation object is allocated, reducing the overall
memory footprint to be approximately one reference per object found
in the current pack file (the pointer in the BlockList). This saves
considerable working set memory compared to the prior version that
made and held onto a new representation for every ObjectToPack.
Clip the configured limit to Integer.MAX_VALUE at the top of the
loop, saving a compare branch per object considered. This can cut
2M branches out of a repacking of the Linux kernel.
Rewrite the logic so the primary path is to match the conditional;
most objects are larger than BLKSZ (16 bytes) and less than limit.
This may help branch prediction on CPUs if the CPU tries to assume
execution takes the side of the branch and not the second.
projects / jgit.git / log