File pairs that are very dissimilar during a diff were not being
broken apart into their constituent ADD/DELETE pairs. The leads to
sub-optimal rename detection. Take, for example, this situation:
A file exists at src/a.txt containing "foo". A user renames src/a.txt
to src/b.txt, then adds a new src/a.txt containing "bar".
Even though the old a.txt and the new b.txt are identical, the
rename detection algorithm would not detect it as a rename since
it was already paired in a MODIFY. I added code to split all
MODIFYs below a certain score into their constituent ADD/DELETE
pairs. This allows situations like the one I described above to be
more correctly handled.
Change-Id: I22c04b70581f206bbc68c4cd1ee87a1f663b418e
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Add methods to the Repository class which write into MERGE_HEAD
and MERGE_MSG files. Since we have the read methods in the same
class this seems to be the right place.
Change-Id: I5dd65306ceb06e008fcc71b37ca3a649632ba462
Signed-off-by: Christian Halstrick <christian.halstrick@sap.com>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
LockFile.commit fails if another thread concurrently reads
the base file. The problem is fixed by retrying the rename
operation if it fails.
Change-Id: I6bb76ea7f2e6e90e3ddc45f9dd4d69bd1b6fa1eb
Bug: 308506
Signed-off-by: Jens Baumgart <jens.baumgart@sap.com>
There were some broken links, incorrect uses of @value, an invalid
tag and an outdated comment.
Change-Id: I22886bcc869a4b62bd606ebed40669f7b4723664
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
This simplifies the logic for those who already have an ObjectReader
on hand want to reuse it to lookup a single path.
Change-Id: Ief17d6b2a0674ddb34bbc9f43121b756eae960fb
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
This exposes a load and save method, allowing a Repository to denote
that it has a persistent configuration of some kind which can be
accessed by the application, without needing to know exact details
of how its stored .
Change-Id: I7c414bc0f975b80f083084ea875eca25c75a07b2
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
This is e.g. useful when a client of the AddCommand has
additional rules to ignore files. In Eclipse a resource can
be set to derived or be excluded by preferences.
Change-Id: I6c47e54a1ce26315faf5ed0723298ad2c2db197c
Signed-off-by: Stefan Lay <stefan.lay@sap.com>
The working tree iterator has perfect knowledge of the path structure
as well as immediate information about whether or not an ignore file
even exists at this level. We can exploit that to simplify the
logic and running time for testing ignored file status by pushing
all of the checks down into the iterator itself.
Change-Id: I22ff534853e8c5672cc5c2d9444aeb14e294070e
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
CC: Charley Wang <chwang@redhat.com>
CC: Chris Aniszczyk <caniszczyk@gmail.com>
CC: Stefan Lay <stefan.lay@sap.com>
CC: Matthias Sohn <matthias.sohn@sap.com>
GitIndex.write fails if another thread concurrently reads
the index file. The problem is fixed by retrying the rename
operation if it fails.
Bug: 311051
Change-Id: Ib243d2a90adae312712d02521de4834d06804944
Signed-off-by: Jens Baumgart <jens.baumgart@sap.com>
The WorkingTreeIterator has a method to check whether
the current file differs from the corresponding index
entry. This commit improves this check to also handle
racy git situations.
See http://git.kernel.org/?p=git/git.git;a=blob;f=Documentation/technical/racy-git.txt;hb=HEAD
Change-Id: I3ad0897211dcbb2eac9eebcb19d095a5052fb06b
Signed-off-by: Christian Halstrick <christian.halstrick@sap.com>
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
To mark an entry racily clean we set its length to 0 (like native git
does). Entries which are not racily clean and have zero length can be
distinguished from racily clean entries by checking P_OBJECTID
against the SHA1 of empty content. When length is 0 and P_OBJECTID is
different from SHA1 of empty content we know the entry is marked
racily clean.
See http://dev.eclipse.org/mhonarc/lists/jgit-dev/msg00488.html
Change-Id: I689552931441ab51964b430b303160c9126b66af
Signed-off-by: Christian Halstrick <christian.halstrick@sap.com>
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
We have a constant for .gitignore, so use it. While we are in
the same method, correct the reference of ".git" to be the actual
GIT_DIR given. This might not be within the work tree if the
GIT_DIR and GIT_WORK_TREE environment variables were used.
Change-Id: I38e1cec13405109b9c347858b38dd9fb2f1f2560
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
CC: Charley Wang <chwang@redhat.com>
CC: Chris Aniszczyk <caniszczyk@gmail.com>
CC: Stefan Lay <stefan.lay@sap.com>
CC: Matthias Sohn <matthias.sohn@sap.com>
This never should have been exposed on the top of the
AbstractTreeIterator type hierarchy. There is no concept of a
timestamp in a canonical tree read from the object database, and
the time in the DirCache isn't what we want here either.
Actually all that we need is to find the files whose names are
".gitignore" and are below the root directory. We can accomplish
that with a suffix filter, and process them immediately.
Change-Id: Ib09cbf81a9e038452ce491385c65498312e2916b
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
CC: Charley Wang <chwang@redhat.com>
CC: Chris Aniszczyk <caniszczyk@gmail.com>
CC: Stefan Lay <stefan.lay@sap.com>
CC: Matthias Sohn <matthias.sohn@sap.com>
If we have two adds of the same object but no deletes the detector
threw an NPE because the entry that came back from the deleted map
was null (no matching objects). In this case we need to put the
adds all back onto the list of left over additions since they did
not match a delete.
Change-Id: Ie68fbe7426b4dc0cb571a08911c7adbffff755d5
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
CC: Jeffrey Schumacher" <jeffschu@google.com>
We didn't correctly handle the zlib trailer for an object. If the
trailer bytes were outside of the current buffer window but we had
fully inflated the object itself, we broke out of the loop (as we had
our target size) but inflate wasn't finished (as it did not yet get
the trailer) so we failed the test and threw a corruption exception.
Use an infinite loop and only break out when the inflater is done.
Change-Id: I7c9bbbeb577a990d9bc56a50ebd485935460f6c8
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
The DeltaCache will most likely need to copy the compressed delta
into a new buffer in order to compact away the wasted space at the
end caused by over allocation. Since we don't need the uncompressed
format anymore, null out our only reference to it so the GC can
reclaim this memory if it needs to perform a collection in order
to satisfy the cache's allocation attempt.
Change-Id: I50403cfd2e3001b093f93a503cccf7adab43cc9d
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
A programming error using the Inflater API led to an infinite
loop within IndexPack, caused by the Inflater returning 0 from
the inflate() method, but it didn't want more input. This happens
when it has reached the end of the stream, or has reached a spot
asking for an external dictionary. Such a case is a failure for us,
and we should abort out.
Thanks to Alex for pointing out that we had 3 implementations of
the inflate rountine, which should be consolidated into one and
use a switch to determine where to load data from.
Bug: 317416
Change-Id: I34120482375b687ea36ed9154002d77047e94b1f
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
During the exact rename detection phase in RenameDetector, ties were
resolved on a first-found basis. I added support for file path based
tie breaking during that phase. Basically, there are four situations
that have to be handled:
One add matching one delete:
In this simple case, we pair them as a rename.
One add matching many deletes:
Find the delete whos path matches the add the closest, and
pair them as a rename.
Many adds matching one delete:
Similar to the above case, we find the add that matches the
delete the closest, and pair them as a rename. The other adds
are marked as copies of the delete.
Many adds matching many deletes:
Build a scoring matrix similar to the one used for content-
based matching, scoring instead by file path. Some of the
utility functions in SimilarityRenameDetector are used in
this case, as we use the same encoding scheme. Once the
matrix is built, scan it for the best matches, marking them
as renames. The rest are marked as copies.
I don't particularly like the idea of using utility functions right
out of SimilarityRenameDetector, but it works for the moment. A later
commit will likely refactor this into a common utility class, as well
as bringing exact rename detection out of RenameDetector and into a
separate class, much like SimilarityRenameDetector.
Change-Id: I1fb08390aebdcbf20d049aecf402a36506e55611
Added possibility to compare the current entry of a WorkingTreeIterator
to a given DirCacheEntry. This is done to detect whether an entry
in the index is dirty or not. 'Dirty' means that the file in the working tree
is different from what's in the index. Merge algorithms will make use of
this to detect conflicts.
Change-Id: I3ff847f4bf392553dcbd6ee236c6ca32a13eedeb
Signed-off-by: Christian Halstrick <christian.halstrick@sap.com>
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
When the path is prefixed with ~ the URI parser thought about this
as /~. Strip the / if the next character is the tilde.
Bug: 307017
Change-Id: I58203e5617956b46d83e8987d1f8042beddffac3
Signed-off-by: Robin Rosenberg <robin.rosenberg@dewire.com>
The new Add command adds files to the Git Index.
It uses the DirCache to access the git index. It
works also in case of an existing conflict.
Fileglobs (e.g. *.c) are not yet supported.
The new Add command does add ignored files because
there is no gitignore support in jgit yet.
Bug: 318440
Change-Id: If16fdd4443e46b27361c2a18ed8f51668af5d9ff
Signed-off-by: Stefan Lay <stefan.lay@sap.com>
This patch adds ignore compatibility to jgit. It encompasses
exclude files as well as .gitignore. Uses TreeWalk and
FileTreeIterator to find nodes and parses .gitignore
files when required. The patch includes a simple cache that
can be used to save results and avoid excessive gitignore
parsing.
CQ: 4302
Bug: 303925
Change-Id: Iebd7e5bb534accca4bf00d25bbc1f561d7cad11b
Signed-off-by: Chris Aniszczyk <caniszczyk@gmail.com>
Signed-off-by: Stefan Lay <stefan.lay@sap.com>
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>
Optimized a small loop in findExactRenames. The loop would go through
all the items in a list of DiffEntries even after it already found
what it was looking for. I made it break out of the loop as soon as
a good match was found.
Change-Id: I28741e0c49ce52d8008930a87cd1db7037700a61
The javadoc for the setRenameLimit method in RenameDetector said
that you could only have limits in the range (0,100), implying
that 0 and 100 were illegal inputs. The code, however, allowed 0 and
100. I changed the javadoc to say that the range [0,100] was legal.
I also documented the IllegalArgumentException that is thrown if the
limit is outside that range.
Change-Id: I916838f254859f6f0e1516bb55b8e7dc87e57dc2
The scoring method was not taking into account the similarity of
the file paths and file names. I changed the metric so that it is 99%
based on content (which used to be 100% of the old metric), and 1%
based on path similarity. Of that 1%, half (.5% of the total final
score) is based on the actual file names (e.g. "foo.java"), and half
on the directory (e.g. "src/com/foo/bar/").
Change-Id: I94f0c23bf6413c491b10d5625f6ad7d2ecfb4def
The scoring logic in SimilarityIndex was dividing by the max file
size. If both files are empty, this would cause a div by zero
error. This case cannot currently happen, since two empty files
would have the same SHA1, and would therefore be caught in the
earlier SHA1 based detection pass. Still, if this logic eventually
gets separated from that pass, a div by zero error would occur.
I changed the logic to instead consider two empty files to have a
similarity score of 100.
Change-Id: Ic08e18a066b8fef25bb5e7c62418106a8cee762a
Prior to this change, files that were very different in size (enough
so that they could not have enough in common to be detected as
renames) were still having their scores calculated. I added an
optimization to skip such files. For example, if the rename detection
threshold is 60%, the larger file is 200kb, and the smaller file is
50kb, the pair cannot be counted as a rename since they cannot
possibly share 60% of their content in common. (200*.6=120, 120>50)
Change-Id: Icd8315412d5de6292839778e7cea7fe6f061b0fc
The pack.windowlimit configuration parameter places an upper bound
on the number of bytes used by the DeltaWindow class as it scans
through the object list. If memory usage would exceed the limit
the window is temporarily decreased in size to keep memory used
within that bound.
Change-Id: I09521b8f335475d8aee6125826da8ba2e545060d
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
If we have multiple CPUs available, packing usually goes faster
when each CPU is assigned a slice of the available search space.
The number of threads to use is guessed from the runtime if it
wasn't set by the caller, or wasn't set in the configuration.
Change-Id: If554fd8973db77632a52a0f45377dd6ec13fc220
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
PackWriter now caches small deltas, or deltas that are very tiny
compared to their source inputs, so that the writing phase goes
faster by reusing those cached deltas.
The cached data is stored compressed, which usually translates to
a bigger footprint due to deltas being very hard to compress, but
saves time during writing by avoiding the deflate step. They are
held under SoftReferences so that the JVM GC can clear out deltas
if memory gets very tight. We would rather continue working and
spend a bit more CPU time during writing than crash due to OOME.
To avoid OutOfMemoryErrors during the caching phase we also trap
OOME and just abort out of the caching.
Because deflateBound() always produces something larger than what
we need to actually store the deflated data, we copy it over into
a new buffer if the actual length doesn't match the buffer length.
When packing jgit.git this saves over 111 KiB in the cache, and is
thus a worthwhile hit on CPU time.
To further save memory we store the inflated size of the delta
(which we need for the object header) in the same field as the
pathHash, as the pathHash is no longer necessary by this phase
of the packing algorithm.
Change-Id: I0da0c600d845e8ec962289751f24e65b5afa56d7
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
PackWriter now produces new deltas if there is not a suitable delta
available for reuse from an existing pack file. This permits JGit to
send less data on the wire by sending a delta relative to an object
the other side already has, instead of sending the whole object.
The delta searching algorithm is similar in style to what C Git
uses, but apparently has some differences (see below for more on).
Briefly, objects that should be considered for delta compression are
pushed onto a list. This list is then sorted by a rough similarity
score, which is derived from the path name the object was discovered
at in the repository during object counting. The list is then
walked in order.
At each position in the list, up to $WINDOW objects prior to it
are attempted as delta bases. Each object in the window is tried,
and the shortest delta instruction sequence selects the base object.
Some rough rules are used to prevent pathological behavior during
this matching phase, like skipping pairings of objects that are
not similar enough in size.
PackWriter intentionally excludes commits and annotated tags from
this new delta search phase. In the JGit repository only 28 out
of 2600+ commits can be delta compressed by C Git. As the commit
count tends to be a fair percentage of the total number of objects
in the repository, and they generally do not delta compress well,
skipping over them can improve performance with little increase in
the output pack size.
Because this implementation was rebuilt from scratch based on my own
memory of how the packing algorithm has evolved over the years in
C Git, PackWriter, DeltaWindow, and DeltaEncoder don't use exactly
the same rules everywhere, and that leads JGit to produce different
(but logically equivalent) pack files.
Repository | Pack Size (bytes) | Packing Time
| JGit - CGit = Difference | JGit / CGit
-----------+----------------------------------+-----------------
git | 25094348 - 24322890 = +771458 | 59.434s / 59.133s
jgit | 5669515 - 5709046 = - 39531 | 6.654s / 6.806s
linux-2.6 | 389M - 386M = +3M | 20m02s / 18m01s
For the above tests pack.threads was set to 1, window size=10,
delta depth=50, and delta and object reuse was disabled for both
implementations. Both implementations were reading from an already
fully packed repository on local disk. The running time reported
is after 1 warm-up run of the tested implementation.
PackWriter is writing 771 KiB more data on git.git, 3M more on
linux-2.6, but is actually 39.5 KiB smaller on jgit.git. Being
larger by less than 0.7% on linux-2.6 isn't bad, nor is taking an
extra 2 minutes to pack. On the running time side, JGit is at a
major disadvantage because linux-2.6 doesn't fit into the default
WindowCache of 20M, while C Git is able to mmap the entire pack and
have it available instantly in physical memory (assuming hot cache).
CGit also has a feature where it caches deltas that were created
during the compression phase, and uses those cached deltas during
the writing phase. PackWriter does not implement this (yet),
and therefore must create every delta twice. This could easily
account for the increased running time we are seeing.
Change-Id: I6292edc66c2e95fbe45b519b65fdb3918068889c
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
This is a horribly crude application, it doesn't even verify that
the object its dumping is delta encoded. Its method of getting the
delta is pretty abusive to the public PackWriter API, because right
now we don't want to expose the real internal low-level methods
actually required to do this.
Change-Id: I437a17ceb98708b5603a2061126eb251e82f4ed4
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
DeltaIndex is a simple pack style delta generator. The function works
by creating a compact index of a source buffer's blocks, and then
walking a sliding window along a desired result buffer, searching for
the window in the index. When a match is found, the window is
stretched to the longest possible length that is common with the
source buffer, and a copy instruction is created.
Rabin's polynomial hash function is used to compute the hash for a
block, permitting efficient sliding of the window in single byte
increments. The update function to slide one byte originated from
David Mazieres' work in LBFS, and our implementation of the update
step was certainly inspired by the initial work Geert Bosch proposed
for C Git in http://marc.info/?l=git&m=114565424620771&w=2.
To ensure the encoder runs in linear time with respect to the size of
the two input buffers (source and result), the maximum number of
blocks that can share the same position in the index's hashtable is
capped at a constant number. This prevents bad inputs from causing
the encoder to run in quadratic time, but comes with a penalty of
creating a longer delta due to fewer considered copy positions.
Strange hackery is used to cap the amount of memory used by the index
to be no more than 12 bytes for every 16 bytes of source buffer, no
matter what the JVM per-object overhead is. This permits an index to
always be no larger than 1.75x the source buffer length, which is an
important feature to support large windows of candidates to match
against while packing. Here the strange hackery is nothing more than
a manually managed chained hashtable, where pointers are array indexes
into storage arrays rather than object references.
Computation of the hash function for a single fixed sized block is
done through an unrolled loop, where the first 4 iterations have been
manually reduced down to eliminate unnecessary instructions. The
pattern is derived from ObjectId.equals(byte[], int, byte[], int),
where we have unrolled the loop required to compare two 20 byte
arrays. Hours of testing with the Sun 1.6 JRE concluded that the
non-obvious "foo[idx + 1]" style of reference is faster than
"foo[idx++]", and so that is what we use here during hashing.
Change-Id: If9fb2a1524361bc701405920560d8ae752221768
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Its useful to know what the flags are or what the base that was
selected is. Dump these out as part of the object's toString.
Change-Id: I8810067fb8337b08b4fcafd5f9ea3e1e31ca6726
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
A subclass may want to use this method to release handles that are
caching reuse information. Make it protected so they can override
it and update themselves.
Change-Id: I2277a56ad28560d2d2d97961cbc74bc7405a70d4
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Searching for reuse candidates should be fast compared to actually
doing delta compression. So pull the progress monitor out of this
phase and rename it back to identify the compressing objects state.
Change-Id: I5eb80919f21c1251e0e3420ff7774126f1f79b27
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Long ago when PackWriter is first written we thought that the delta
depth could be updated automatically. But its never used. Instead
make this a simple standard setter so the caller can more directly
set the delta depth of this object. This permits us to configure a
depth that takes into account more than just the depth of another
object in this same pack.
Change-Id: I1d71b74f2edd7029b8743a2c13b591098ce8cc8f
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
C Git's fast-import uses this to determine the maximum file size
that it tries to delta compress, anything equal to or above this
setting is stored with as a whole object with simple deflate.
Define the configuration so we can use it later.
Change-Id: Iea46e787d019a1b6c51135cc73d7688a02e207f5
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
This flag will later control whether or not PackWriter search for a
delta base for this object. Edge objects will never get searched,
as the writer won't be outputting them, so they should always have
this flag set on. Sometime in the future this flag should also be
set for file blobs on file paths that have the "-delta" gitattribute
set in the repository's attributes file.
Change-Id: I6e518e1a6996c8ce00b523727f1b605e400e82c6
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
We now at least import other pack settings like pack.window, which
means we can later use these to control how we search for deltas.
The compression level was fixed to use pack.compression rather than
the loose object core.compression setting.
Change-Id: I72ff6d481c936153ceb6a9e485fa731faf075a9a
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
C Git allows this and it is quite handy.
Change-Id: I1d0238b43fca931ad2079649fb7b431e2815c351
Signed-off-by: Robin Rosenberg <robin.rosenberg@dewire.com>
We need to remember these so we can later cluster objects that
have similar file paths near each other as we search for deltas
between them.
Change-Id: I52cb1e4ca15c9c267a2dbf51dd0d795f885f4cf8
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
PackWriter wants to categorize objects that are similar in path name,
so blobs that are probably from the same file (or same sort of file)
can be delta compressed against each other. Avoid converting into
a string by performing the hashing directly against the path buffer
in the tree iterator.
We only hash the last 16 bytes of the path, and we try avoid any
spaces, as we want the suffix of a file such as ".java" to be more
important than the directory it is in, like "src".
Change-Id: I31770ee711526306769a6f534afb19f937e0ba85
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
This is an informational function used by PackWriter to help it
better organize objects for delta compression. Storage systems
can implement it to provide up more detailed size information,
or they can simply rely on the default behavior that uses the
ObjectLoader obtained from open.
For local file storage, we can obtain this information faster
through specialized routines that parse a pack object header.
Change-Id: I13a09b4effb71ea5151b51547f7d091564531e58
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
If the heap limit was set to something smaller than 8 KiB, we were
still allocating the full 8 KiB block size, and accepting up to
the amount we allocated by. Instead actually put a hard cap on
the limit.
Change-Id: Id1da26fde2102e76510b1da4ede8493928a981cc
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Added support for converting DiffEntrys to FileHeaders. FileHeaders
are DiffEntrys with a buffer containing the diff output as well as
a list of HunkHeaders. The HunkHeaders contain EditLists. The
createFileHeader(DiffEntry) method in DiffFormatter performs a Myers
Diff on the files refered to by the DiffEntry, then puts the returned
EditList into a single HunkHeader, which is then put into the
FileHeader to be returned. It also generates the appropriate diff
header an puts it into the FileHeader's buffer. The rest of the diff
output, which would normally be parsed to generate the HunkHeaders,
is not generated. In fact, the purpose of this method is to avoid
the costly diff output generation and parsing normally required to
create a FileHeader.
Change-Id: I7d8b18c0f6c85e3d02ad58995d3d231e69af5887
Jeff Schumacher
Christian Halstrick
Jens Baumgart
Robin Stocker
Shawn O. Pearce
Stefan Lay
Robin Rosenberg
Charley Wang
Matthias Sohn