path: root/diffcore-rename.c
AgeCommit message (Collapse)Author
2011-02-19diffcore-rename: improve estimate_similarity() heuristicsLinus Torvalds
The logic to quickly dismiss potential rename pairs was broken. It would too eagerly dismiss possible renames when all of the difference was due to pure new data (or deleted data). Signed-off-by: Linus Torvalds <> Signed-off-by: Junio C Hamano <>
2011-02-19diffcore-rename: properly honor the difference between -M and -CLinus Torvalds
We would allow rename detection to do copy detection even when asked purely for renames. That confuses users, but more importantly it can terminally confuse the recursive merge rename logic. Signed-off-by: Linus Torvalds <> Signed-off-by: Junio C Hamano <>
2011-02-19for_each_hash: allow passing a 'void *data' pointer to callbackLinus Torvalds
For the find_exact_renames() function, this allows us to pass the diff_options structure pointer to the low-level routines. We will use that to distinguish between the "rename" and "copy" cases. Signed-off-by: Linus Torvalds <> Signed-off-by: Junio C Hamano <>
2010-05-07Add a macro DIFF_QUEUE_CLEAR.Bo Yang
Refactor the diff_queue_struct code, this macro help to reset the structure. Signed-off-by: Bo Yang <> Signed-off-by: Junio C Hamano <>
2009-11-21diffcore-rename: reduce memory footprint by freeing blob data earlyJunio C Hamano
After running one round of estimate_similarity(), filespecs on either side will have populated their cnt_data fields, and we do not need the blob text anymore. We used to retain the blob data to optimize for smaller projects (not freeing the blob data here would mean that the final output phase would not have to re-read it), but we are efficient enough without such optimization for smaller projects anyway, and freeing memory early will help larger projects. Signed-off-by: Junio C Hamano <>
2009-04-23Fix typos / spelling in commentsMike Ralphson
Signed-off-by: Mike Ralphson <> Signed-off-by: Junio C Hamano <>
2009-01-21Rename detection: Avoid repeated filespec populationBjörn Steinbrink
In diffcore_rename, we assume that the blob contents in the filespec aren't required anymore after estimate_similarity has been called and thus we free it. But estimate_similarity might return early when the file sizes differ too much. In that case, cnt_data is never set and the next call to estimate_similarity will populate the filespec again, eventually rereading the same blob over and over again. To fix that, we first get the blob sizes and only when the blob contents are actually required, and when cnt_data will be set, the full filespec is populated, once. Signed-off-by: Björn Steinbrink <> Signed-off-by: Junio C Hamano <>
2008-10-28Add file delete/create info when we overflow rename_limitLinus Torvalds
When we refuse to do rename detection due to having too many files created or deleted, let the user know the numbers. That way there is a reasonable starting point for setting the diff.renamelimit option. Signed-off-by: Linus Torvalds <> Signed-off-by: Junio C Hamano <>
2008-05-03diff: make "too many files" rename warning optionalJeff King
In many cases, the warning ends up as clutter, because the diff is being done "behind the scenes" from the user (e.g., when generating a commit diffstat), and whether we show renames or not is not particularly interesting to the user. However, in the case of a merge (which is what motivated the warning in the first place), it is a useful hint as to why a merge with renames might have failed. This patch makes the warning optional based on the code calling into diffcore. We default to not showing the warning, but turn it on for merges. Signed-off-by: Jeff King <> Signed-off-by: Junio C Hamano <>
2008-04-09Merge branch 'jc/rename'Junio C Hamano
* 'jc/rename' (early part): Optimize rename detection for a huge diff
2008-03-01rename: warn user when we have turned off rename detectionJeff King
Signed-off-by: Jeff King <> Signed-off-by: Junio C Hamano <>
2008-02-13Optimize rename detection for a huge diffJunio C Hamano
When there are N deleted paths and M created paths, we used to allocate (N x M) "struct diff_score" that record how similar each of the pair is, and picked the <src,dst> pair that gives the best match first, and then went on to process worse matches. This sorting is done so that when two new files in the postimage that are similar to the same file deleted from the preimage, we can process the more similar one first, and when processing the second one, it can notice "Ah, the source I was planning to say I am a copy of is already taken by somebody else" and continue on to match itself with another file in the preimage with a lessor match. This matters to a change introduced between 1.5.3.X series and 1.5.4-rc, that lets the code to favor unused matches first and then falls back to using already used matches. This instead allocates and keeps only a handful rename source candidates per new files in the postimage. I.e. it makes the memory requirement from O(N x M) to O(M). For each dst, we compute similarlity with all sources (i.e. the number of similarity estimate computations is still O(N x M)), but we keep handful best src candidates for each dst. Signed-off-by: Junio C Hamano <>
2007-11-30Fix a pathological case in git detecting proper renamesLinus Torvalds
On Thu, 29 Nov 2007, Jeff King wrote: > > I think it will get worse, because you are simultaneously calculating > all of the similarity scores bit by bit rather than doing a loop. Though > perhaps you mean at the end you will end up with a list of src/dst pairs > sorted by score, and you can loop over that. Well, after thinking about this a bit, I think there's a solution that may work well with the current thing too: instead of looping just *once* over the list of rename pairs, loop twice - and simply refuse to do copies on the first loop. This trivial patch does that, and turns Kumar's test-case into a perfect rename list. It's not pretty, it's not smart, but it seems to work. There's something to be said for keeping it simple and stupid. And it should not be nearly as expensive as it may _look_. Yes, the loop is "(i = 0; i < num_create * num_src; i++)", but the important part is that the whole array is sorted by rename score, and we have a if (mx[i].score < minimum_score) break; in it, so uthe loop actually would tend to terminate rather quickly. Anyway, Kumar, the thing to take away from this is: - git really doesn't even *care* about the whole "rename detection" internally, and any commits you have done with renames are totally independent of the heuristics we then use to *show* the renames. - the rename detection really is for just two reasons: (a) keep humans happy, and keep the diffs small and (b) help automatic merging across renames. So getting renames right is certainly good, but it's more of a "politeness" issue than a "correctness" issue, although the merge portion of it does matter a lot sometimes. - the important thing here is that you can commit your changes and not worry about them being somehow "corrupted" by lack of rename detection, even if you commit them with a version of git that doesn't do rename detection the way you expected it. The rename detection is an "after-the-fact" thing, not something that actually gets saved in the repository, which is why we can change the heuristics _after_ seeing examples, and the examples magically correct themselves! - try out the two patches I've posted, and see if they work for you. They pass the test-suite, and the output for your example commit looks sane, but hey, if you have other test-cases, try them out. Here's Kumar's pretty diffstat with both my patches: Makefile | 6 +++--- board/{cds => freescale}/common/cadmus.c | 0 board/{cds => freescale}/common/cadmus.h | 0 board/{cds => freescale}/common/eeprom.c | 0 board/{cds => freescale}/common/eeprom.h | 0 board/{cds => freescale}/common/ft_board.c | 0 board/{cds => freescale}/common/via.c | 0 board/{cds => freescale}/common/via.h | 0 board/{cds => freescale}/mpc8541cds/Makefile | 0 board/{cds => freescale}/mpc8541cds/ | 0 board/{cds => freescale}/mpc8541cds/init.S | 0 board/{cds => freescale}/mpc8541cds/mpc8541cds.c | 0 board/{cds => freescale}/mpc8541cds/ | 4 ++-- board/{cds => freescale}/mpc8548cds/Makefile | 0 board/{cds => freescale}/mpc8548cds/ | 0 board/{cds => freescale}/mpc8548cds/init.S | 0 board/{cds => freescale}/mpc8548cds/mpc8548cds.c | 0 board/{cds => freescale}/mpc8548cds/ | 4 ++-- board/{cds => freescale}/mpc8555cds/Makefile | 0 board/{cds => freescale}/mpc8555cds/ | 0 board/{cds => freescale}/mpc8555cds/init.S | 0 board/{cds => freescale}/mpc8555cds/mpc8555cds.c | 0 board/{cds => freescale}/mpc8555cds/ | 4 ++-- 23 files changed, 9 insertions(+), 9 deletions(-) and here it is before: Makefile | 6 +- board/cds/mpc8548cds/Makefile | 60 ----- board/cds/mpc8555cds/Makefile | 60 ----- board/cds/mpc8555cds/init.S | 255 -------------------- board/cds/mpc8555cds/ | 150 ------------ board/{cds => freescale}/common/cadmus.c | 0 board/{cds => freescale}/common/cadmus.h | 0 board/{cds => freescale}/common/eeprom.c | 0 board/{cds => freescale}/common/eeprom.h | 0 board/{cds => freescale}/common/ft_board.c | 0 board/{cds => freescale}/common/via.c | 0 board/{cds => freescale}/common/via.h | 0 board/{cds => freescale}/mpc8541cds/Makefile | 0 board/{cds => freescale}/mpc8541cds/ | 0 board/{cds => freescale}/mpc8541cds/init.S | 0 board/{cds => freescale}/mpc8541cds/mpc8541cds.c | 0 board/{cds => freescale}/mpc8541cds/ | 4 +- .../mpc8541cds => freescale/mpc8548cds}/Makefile | 0 board/{cds => freescale}/mpc8548cds/ | 0 board/{cds => freescale}/mpc8548cds/init.S | 0 board/{cds => freescale}/mpc8548cds/mpc8548cds.c | 0 board/{cds => freescale}/mpc8548cds/ | 4 +- .../mpc8541cds => freescale/mpc8555cds}/Makefile | 0 board/{cds => freescale}/mpc8555cds/ | 0 .../mpc8541cds => freescale/mpc8555cds}/init.S | 0 board/{cds => freescale}/mpc8555cds/mpc8555cds.c | 0 .../mpc8541cds => freescale/mpc8555cds}/ | 4 +- 27 files changed, 9 insertions(+), 534 deletions(-) so it certainly makes the diffs prettier. Linus Signed-off-by: Junio C Hamano <>
2007-11-30Fix a pathological case in git detecting proper renamesLinus Torvalds
Kumar Gala had a case in the u-boot archive with multiple renames of files with identical contents, and git would turn those into multiple "copy" operations of one of the sources, and just deleting the other sources. This patch makes the git exact rename detection prefer to spread out the renames over the multiple sources, rather than do multiple copies of one source. NOTE! The changes are a bit larger than required, because I also renamed the variables named "one" and "two" to "target" and "source" respectively. That makes the logic easier to follow, especially as the "one" was illogically the target and not the soruce, for purely historical reasons (this piece of code used to traverse over sources and targets in the wrong order, and when we fixed that, we didn't fix the names back then. So I fixed them now). The important part of this change is just the trivial score calculations for when files have identical contents: /* Give higher scores to sources that haven't been used already */ score = !source->rename_used; score += basename_same(source, target); and when we have multiple choices we'll now pick the choice that gets the best rename score, rather than only looking at whether the basename matched. It's worth noting a few gotchas: - this scoring is currently only done for the "exact match" case. In particular, in Kumar's example, even after this patch, the inexact match case is still done as a copy+delete rather than as two renames: delete mode 100644 board/cds/mpc8555cds/ copy board/{cds => freescale}/mpc8541cds/ (97%) rename board/{cds/mpc8541cds => freescale/mpc8555cds}/ (97%) because apparently the "cds/mpc8541cds/" copy looked a bit more similar to both end results. That said, I *suspect* we just have the exact same issue there - the similarity analysis just gave identical (or at least very _close_ to identical) similarity points, and we do not have any logic to prefer multiple renames over a copy/delete there. That is a separate patch. - When you have identical contents and identical basenames, the actual entry that is chosen is still picked fairly "at random" for the first one (but the subsequent ones will prefer entries that haven't already been used). It's not actually really random, in that it actually depends on the relative alphabetical order of the files (which in turn will have impacted the order that the entries got hashed!), so it gives consistent results that can be explained. But I wanted to point it out as an issue for when anybody actually does cross-renames. In Kumar's case the choice is the right one (and for a single normal directory rename it should always be, since the relative alphabetical sorting of the files will be identical), and we now get: rename board/{cds => freescale}/mpc8541cds/init.S (100%) rename board/{cds => freescale}/mpc8548cds/init.S (100%) which is the "expected" answer. However, it might still be better to change the pedantic "exact same basename" on/off choice into a more graduated "how similar are the pathnames" scoring situation, in order to be more likely to get the exact rename choice that people *expect* to see, rather than other alternatives that may *technically* be equally good, but are surprising to a human. It's also unclear whether we should consider "basenames are equal" or "have already used this as a source" to be more important. This gives them equal weight, but I suspect we might want to just multiple the "basenames are equal" weight by two, or something, to prefer equal basenames even if that causes a copy/delete pair. I dunno. Anyway, what I'm just saying in a really long-winded manner is that I think this is right as-is, but it's not the complete solution, and it may want some further tweaking in the future. Signed-off-by: Linus Torvalds <> Signed-off-by: Junio C Hamano <>
2007-10-27Do the fuzzy rename detection limits with the exact renames removedLinus Torvalds
When we do the fuzzy rename detection, we don't care about the destinations that we already handled with the exact rename detector. And, in fact, the code already knew that - but the rename limiter, which used to run *before* exact renames were detected, did not. This fixes it so that the rename detection limiter now bases its decisions on the *remaining* rename counts, rather than the original ones. Signed-off-by: Linus Torvalds <> Signed-off-by: Junio C Hamano <>
2007-10-27Fix ugly magic special case in exact rename detectionLinus Torvalds
For historical reasons, the exact rename detection had populated the filespecs for the entries it compared, and the rest of the similarity analysis depended on that. I hadn't even bothered to debug why that was the case when I re-did the rename detection, I just made the new one have the same broken behaviour, with a note about this special case. This fixes that fixme. The reason the exact rename detector needed to fill in the file sizes of the files it checked was that the _inexact_ rename detector was broken, and started comparing file sizes before it filled them in. Fixing that allows the exact phase to do the sane thing of never even caring (since all *it* cares about is really just the SHA1 itself, not the size nor the contents). It turns out that this also indirectly fixes a bug: trying to populate all the filespecs will run out of virtual memory if there is tons and tons of possible rename options. The fuzzy similarity analysis does the right thing in this regard, and free's the blob info after it has generated the hash tables, so the special case code caused more trouble than just some extra illogical code. Signed-off-by: Linus Torvalds <> Signed-off-by: Junio C Hamano <>
2007-10-27Do exact rename detection regardless of rename limitsLinus Torvalds
Now that the exact rename detection is linear-time (with a very small constant factor to boot), there is no longer any reason to limit it by the number of files involved. In some trivial testing, I created a repository with a directory that had a hundred thousand files in it (all with different contents), and then moved that directory to show the effects of renaming 100,000 files. With the new code, that resulted in [torvalds@woody big-rename]$ time ~/git/git show -C | wc -l 400006 real 0m2.071s user 0m1.520s sys 0m0.576s ie the code can correctly detect the hundred thousand renames in about 2 seconds (the number "400006" comes from four lines for each rename: diff --git a/really-big-dir/file-1-1-1-1-1 b/moved-big-dir/file-1-1-1-1-1 similarity index 100% rename from really-big-dir/file-1-1-1-1-1 rename to moved-big-dir/file-1-1-1-1-1 and the extra six lines is from a one-liner commit message and all the commit information and spacing). Most of those two seconds weren't even really the rename detection, it's really all the other stuff needed to get there. With the old code, this wouldn't have been practically possible. Doing a pairwise check of the ten billion possible pairs would have been prohibitively expensive. In fact, even with the rename limiter in place, the old code would waste a lot of time just on the diff_filespec checks, and despite not even trying to find renames, it used to look like: [torvalds@woody big-rename]$ time git show -C | wc -l 1400006 real 0m12.337s user 0m12.285s sys 0m0.192s ie we used to take 12 seconds for this load and not even do any rename detection! (The number 1400006 comes from fourteen lines per file moved: seven lines each for the delete and the create of a one-liner file, and the same extra six lines of commit information). Signed-off-by: Linus Torvalds <> Signed-off-by: Junio C Hamano <>
2007-10-27Do linear-time/space rename logic for exact renamesLinus Torvalds
This implements a smarter rename detector for exact renames, which rather than doing a pairwise comparison (time O(m*n)) will just hash the files into a hash-table (size O(n+m)), and only do pairwise comparisons to renames that have the same hash (time O(n+m) except for unrealistic hash collissions, which we just cull aggressively). Admittedly the exact rename case is not nearly as interesting as the generic case, but it's an important case none-the-less. A similar general approach should work for the generic case too, but even then you do need to handle the exact renames/copies separately (to avoid the inevitable added cost factor that comes from the _size_ of the file), so this is worth doing. In the expectation that we will indeed do the same hashing trick for the general rename case, this code uses a generic hash-table implementation that can be used for other things too. In fact, we might be able to consolidate some of our existing hash tables with the new generic code in hash.[ch]. Signed-off-by: Linus Torvalds <> Signed-off-by: Junio C Hamano <>
2007-10-27copy vs rename detection: avoid unnecessary O(n*m) loopsLinus Torvalds
The core rename detection had some rather stupid code to check if a pathname was used by a later modification or rename, which basically walked the whole pathname space for all renames for each rename, in order to tell whether it was a pure rename (no remaining users) or should be considered a copy (other users of the source file remaining). That's really silly, since we can just keep a count of users around, and replace all those complex and expensive loops with just testing that simple counter (but this all depends on the previous commit that shared the diff_filespec data structure by using a separate reference count). Note that the reference count is not the same as the rename count: they behave otherwise rather similarly, but the reference count is tied to the allocation (and decremented at de-allocation, so that when it turns zero we can get rid of the memory), while the rename count is tied to the renames and is decremented when we find a rename (so that when it turns zero we know that it was a rename, not a copy). Signed-off-by: Linus Torvalds <> Signed-off-by: Junio C Hamano <>
2007-10-27Ref-count the filespecs used by diffcoreLinus Torvalds
Rather than copy the filespecs when introducing new versions of them (for rename or copy detection), use a refcount and increment the count when reusing the diff_filespec. This avoids unnecessary allocations, but the real reason behind this is a future enhancement: we will want to track shared data across the copy/rename detection. In order to efficiently notice when a filespec is used by a rename, the rename machinery wants to keep track of a rename usage count which is shared across all different users of the filespec. Signed-off-by: Linus Torvalds <> Signed-off-by: Junio C Hamano <>
2007-10-27Split out "exact content match" phase of rename detectionLinus Torvalds
This makes the exact content match a separate function of its own. Partly to cut down a bit on the size of the diffcore_rename() function (which is too complex as it is), and partly because there are smarter ways to do this than an O(m*n) loop over it all, and that function should be rewritten to take that into account. Signed-off-by: Linus Torvalds <> Signed-off-by: Junio C Hamano <>
2007-10-03rename diff_free_filespec_data_large() to diff_free_filespec_blob()Junio C Hamano
Signed-off-by: Junio C Hamano <>
2007-10-03diffcore-rename: cache file deltasJeff King
We find rename candidates by computing a fingerprint hash of each file, and then comparing those fingerprints. There are inherently O(n^2) comparisons, so it pays in CPU time to hoist the (rather expensive) computation of the fingerprint out of that loop (or to cache it once we have computed it once). Previously, we didn't keep the filespec information around because then we had the potential to consume a great deal of memory. However, instead of keeping all of the filespec data, we can instead just keep the fingerprint. This patch implements and uses diff_free_filespec_data_large to accomplish that goal. We also have to change estimate_similarity not to needlessly repopulate the filespec data when we already have the hash. Practical tests showed 4.5x speedup for a 10% memory usage increase. Signed-off-by: Jeff King <> Signed-off-by: Junio C Hamano <>
2007-09-14Fix the rename detection limit checkingLinus Torvalds
This adds more proper rename detection limits. Instead of just checking the limit against the number of potential rename destinations, we verify that the rename matrix (which is what really matters) doesn't grow ridiculously large, and we also make sure that we don't overflow when doing the matrix size calculation. This also changes the default limits from unlimited, to a rename matrix that is limited to 100 entries on a side. You can raise it with the config entry, or by using the "-l<n>" command line flag, but at least the default is now a sane number that avoids spending lots of time (and memory) in situations that likely don't merit it. The choice of default value is of course very debatable. Limiting the rename matrix to a 100x100 size will mean that even if you have just one obvious rename, but you also create (or delete) 10,000 files, the rename matrix will be so big that we disable the heuristics. Sounds reasonable to me, but let's see if people hit this (and, perhaps more importantly, actually *care*) in real life. Signed-off-by: Linus Torvalds <> Signed-off-by: Junio C Hamano <>
2007-07-02Merge branch 'jc/diffcore'Junio C Hamano
* jc/diffcore: diffcore-delta.c: Ignore CR in CRLF for text files diffcore-delta.c: update the comment on the algorithm. diffcore_filespec: add is_binary diffcore_count_changes: pass diffcore_filespec
2007-07-01diffcore_count_changes: pass diffcore_filespecJunio C Hamano
We may want to use richer information on the data we are dealing with in this function, so instead of passing a buffer address and length, just pass the diffcore_filespec structure. Existing callers always call this function with parameters taken from a filespec anyway, so there is no functionality changes. Signed-off-by: Junio C Hamano <>
2007-06-25diffcore-rename: don't change similarity index based on basename equalityRené Scharfe
This implements a suggestion from Johannes. It uses a separate field in struct diff_score to keep the result of the file name comparison in the rename detection logic. This reverts the value of the similarity index to be a function of file contents, only, and basename comparison is only used to decide between files with equal amounts of content changes. Signed-off-by: Rene Scharfe <> Signed-off-by: Junio C Hamano <>
2007-06-23diffcore-rename: favour identical basenamesJohannes Schindelin
When there are several candidates for a rename source, and one of them has an identical basename to the rename target, take that one. Noticed by Govind Salinas, posted by Shawn O. Pearce, partial patch by Linus Torvalds. Signed-off-by: Johannes Schindelin <> Signed-off-by: Junio C Hamano <>
2007-05-07diff -M: release the preimage candidate blobs after rename detection.Junio C Hamano
We released the postimage candidate blobs after we are done to reduce memory pressure. Do the same for preimage candidate blobs. Signed-off-by: Junio C Hamano <>
2007-03-07Cast 64 bit off_t to 32 bit size_tShawn O. Pearce
Some systems have sizeof(off_t) == 8 while sizeof(size_t) == 4. This implies that we are able to access and work on files whose maximum length is around 2^63-1 bytes, but we can only malloc or mmap somewhat less than 2^32-1 bytes of memory. On such a system an implicit conversion of off_t to size_t can cause the size_t to wrap, resulting in unexpected and exciting behavior. Right now we are working around all gcc warnings generated by the -Wshorten-64-to-32 option by passing the off_t through xsize_t(). In the future we should make xsize_t on such problematic platforms detect the wrapping and die if such a file is accessed. Signed-off-by: Shawn O. Pearce <> Signed-off-by: Junio C Hamano <>
2006-12-14Bypass expensive content comparsion during rename detection.Shawn O. Pearce
When comparing file contents during the second loop through a rename detection attempt we can skip the expensive byte-by-byte comparsion if both source and destination files have valid SHA1 values. This improves performance by avoiding either an expensive open/mmap to read the working tree copy, or an expensive inflate of a blob object. Unfortunately we still have to at least initialize the sizes of the source and destination files even if the SHA1 values don't match. Failing to initialize the sizes causes a number of test cases to fail and start reporting different copy/rename behavior than was expected. Signed-off-by: Shawn O. Pearce <> Signed-off-by: Junio C Hamano <>
2006-11-04git-pickaxe: rename detection optimizationJunio C Hamano
The idea is that we are interested in renaming into only one path, so we do not care about renames that happen elsewhere. Signed-off-by: Junio C Hamano <>
2006-08-17Do not use memcmp(sha1_1, sha1_2, 20) with hardcoded length.David Rientjes
Introduces global inline: hashcmp(const unsigned char *sha1, const unsigned char *sha2) Uses memcmp for comparison and returns the result based on the length of the hash name (a future runtime decision). Acked-by: Alex Riesen <> Signed-off-by: David Rientjes <> Signed-off-by: Junio C Hamano <>
2006-08-03diff.c: do not use pathname comparison to tell renamesJunio C Hamano
The final output from diff used to compare pathnames between preimage and postimage to tell if the filepair is a rename/copy. By explicitly marking the filepair created by diffcore_rename(), the output routine, resolve_rename_copy(), does not have to do so anymore. This helps feeding a filepair that has different pathnames in one and two elements to the diff machinery (most notably, comparing two blobs). Signed-off-by: Junio C Hamano <>
2006-07-07diffcore-rename: try matching up renames without populating filespec first.Junio C Hamano
Signed-off-by: Junio C Hamano <>
2006-04-09diffcore-rename: fix merging back a broken pair.Junio C Hamano
When a broken pair is matched up by rename detector to be merged back, we do not want to say it is "dissimilar" with the similarity index. The output should just say they were changed, taking the break score left by the earlier diffcore-break run if any. Signed-off-by: Junio C Hamano <>
2006-03-13Fix up diffcore-rename scoringLinus Torvalds
The "score" calculation for diffcore-rename was totally broken. It scaled "score" as score = src_copied * MAX_SCORE / dst->size; which means that you got a 100% similarity score even if src and dest were different, if just every byte of dst was copied from src, even if source was much larger than dst (eg we had copied 85% of the bytes, but _deleted_ the remaining 15%). That's clearly bogus. We should do the score calculation relative not to the destination size, but to the max size of the two. This seems to fix it. Signed-off-by: Linus Torvalds <> Signed-off-by: Junio C Hamano <>
2006-03-13diffcore-delta: make the hash a bit denser.Junio C Hamano
To reduce wasted memory, wait until the hash fills up more densely before we rehash. This reduces the working set size a bit further. Signed-off-by: Junio C Hamano <>
2006-03-12diffcore-rename: somewhat optimized.Junio C Hamano
This changes diffcore-rename to reuse statistics information gathered during similarity estimation, and updates the hashtable implementation used to keep track of the statistics to be denser. This seems to give better performance. Signed-off-by: Junio C Hamano <>
2006-03-03diffcore-rename: similarity estimator fix.Junio C Hamano
The "similarity" logic was giving added material way too much negative weight. What we wanted to see was how similar the post-change image was compared to the pre-change image, so the natural definition of similarity is how much common things are there, relative to the post-change image's size. This simplifies things a lot. Signed-off-by: Junio C Hamano <>
2006-03-01diffcore-rename: split out the delta counting code.Junio C Hamano
This is to rework diffcore break/rename/copy detection code so that it does not affected when deltifier code gets improved. Signed-off-by: Junio C Hamano <>
2006-02-23diffcore-rename: plug memory leak.Junio C Hamano
Spotted by Nicolas Pitre. Signed-off-by: Junio C Hamano <>
2005-12-26short circuit out of a few places where we would allocate zero bytesEric Wong
dietlibc versions of malloc, calloc and realloc all return NULL if they're told to allocate 0 bytes, causes the x* wrappers to die(). There are several more places where these calls could end up asking for 0 bytes, too... Maybe simply not die()-ing in the x* wrappers if 0/NULL is returned when the requested size is zero is a safer and easier way to go. Signed-off-by: Eric Wong <> Signed-off-by: Junio C Hamano <>
2005-11-21rename detection with -M100 means "exact renames only".Junio C Hamano
When the user is interested in pure renames, there is no point doing the similarity scores. This changes the score argument parsing to special case -M100 (otherwise, it is a precision scaled value 0 <= v < 1 and would mean 0.1, not 1.0 --- if you do mean 0.1, you can say -M1), and optimizes the diffcore_rename transformation to only look at pure renames in that case. Signed-off-by: Junio C Hamano <>
2005-11-15diff: make default rename detection limit configurable.Junio C Hamano
A while ago, a rename-detection limit logic was implemented as a response to this thread: where gitweb was found to be using a lot of time and memory to detect renames on huge commits. git-diff family takes -l<num> flag, and if the number of paths that are rename destination candidates (i.e. new paths with -M, or modified paths with -C) are larger than that number, skips rename/copy detection even when -M or -C is specified on the command line. This commit makes the rename detection limit easier to use. You can have: [diff] renamelimit = 30 in your .git/config file to specify the default rename detection limit. You can override this from the command line; giving 0 means 'unlimited': git diff -M -l0 We might want to change the default behaviour, when you do not have the configuration, to limit it to say 20 paths or so. This would also help the diffstat generation after a big 'git pull'. Signed-off-by: Junio C Hamano <>
2005-09-25Diff: -l<num> to limit rename/copy detection.Junio C Hamano
When many paths are modified, rename detection takes a lot of time. The new option -l<num> can be used to disable rename detection when more than <num> paths are possibly created as renames. Signed-off-by: Junio C Hamano <>
2005-09-15Plug diff leaks.Junio C Hamano
It is a bit embarrassing that it took this long for a fix since the problem was first reported on Aug 13th. Message-ID: <> From: Yasushi SHOJI <> Newsgroups: gmane.comp.version-control.git Subject: [patch] possible memory leak in diff.c::diff_free_filepair() Date: Sat, 13 Aug 2005 19:58:56 +0900 This time I used valgrind to make sure that it does not overeagerly discard memory that is still being used. Signed-off-by: Junio C Hamano <>
2005-09-10Fix copy marking from diffcore-rename.Junio C Hamano
When (A,B) ==> (B,C) rename-copy was detected, we incorrectly said that C was created by copying B. This is because we only check if the path of rename/copy source still exists in the resulting tree to see if the file is renamed out of existence. In this case, the new B is created by copying or renaming A, so the original B is lost and we should say C is a rename of B not a copy of B. Signed-off-by: Junio C Hamano <>
2005-06-29[PATCH] Use enhanced diff_delta() in the similarity estimator.Junio C Hamano
The diff_delta() interface was extended to reject generating too big a delta while we were working on the packed GIT archive format. Take advantage of that when generating delta in the similarity estimator used in diffcore-rename.c Signed-off-by: Junio C Hamano <> Signed-off-by: Linus Torvalds <>
2005-06-26Add a "max_size" parameter to diff_delta()Linus Torvalds
Anything that generates a delta to see if two objects are close usually isn't interested in the delta ends up being bigger than some specified size, and this allows us to stop delta generation early when that happens.