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https://github.com/git/git
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582aa00bdf
Ever since the xdiff library had been introduced to git, all its callers have used the flag XDF_NEED_MINIMAL. It makes sure that the smallest possible diff is produced, but that takes quite some time if there are lots of differences that can be expressed in multiple ways. This flag makes a difference for only 0.1% of the non-merge commits in the git repo of Linux, both in terms of diff size and execution time. The patches there are mostly nice and small. SungHyun Nam however reported a case in a different repo where a diff took more than 20 times longer to generate with XDF_NEED_MINIMAL than without. Rebasing became really slow. This patch removes this flag from all callers. The default of xdiff is saner because it has minimal to no impact in the normal case of small diffs and doesn't incur that much of a speed penalty for large ones. A follow-up patch may introduce a command line option to set the flag if the user needs it, similar to GNU diff's -d/--minimal. Signed-off-by: Rene Scharfe <rene.scharfe@lsrfire.ath.cx> Signed-off-by: Junio C Hamano <gitster@pobox.com>
118 lines
2.4 KiB
C
118 lines
2.4 KiB
C
#include "cache.h"
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#include "run-command.h"
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#include "xdiff-interface.h"
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#include "ll-merge.h"
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#include "blob.h"
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static int fill_mmfile_blob(mmfile_t *f, struct blob *obj)
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{
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void *buf;
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unsigned long size;
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enum object_type type;
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buf = read_sha1_file(obj->object.sha1, &type, &size);
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if (!buf)
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return -1;
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if (type != OBJ_BLOB)
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return -1;
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f->ptr = buf;
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f->size = size;
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return 0;
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}
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static void free_mmfile(mmfile_t *f)
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{
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free(f->ptr);
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}
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static void *three_way_filemerge(const char *path, mmfile_t *base, mmfile_t *our, mmfile_t *their, unsigned long *size)
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{
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int merge_status;
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mmbuffer_t res;
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merge_status = ll_merge(&res, path, base,
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our, ".our", their, ".their", 0);
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if (merge_status < 0)
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return NULL;
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*size = res.size;
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return res.ptr;
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}
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static int common_outf(void *priv_, mmbuffer_t *mb, int nbuf)
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{
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int i;
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mmfile_t *dst = priv_;
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for (i = 0; i < nbuf; i++) {
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memcpy(dst->ptr + dst->size, mb[i].ptr, mb[i].size);
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dst->size += mb[i].size;
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}
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return 0;
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}
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static int generate_common_file(mmfile_t *res, mmfile_t *f1, mmfile_t *f2)
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{
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unsigned long size = f1->size < f2->size ? f1->size : f2->size;
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void *ptr = xmalloc(size);
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xpparam_t xpp;
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xdemitconf_t xecfg;
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xdemitcb_t ecb;
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memset(&xpp, 0, sizeof(xpp));
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xpp.flags = 0;
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memset(&xecfg, 0, sizeof(xecfg));
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xecfg.ctxlen = 3;
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xecfg.flags = XDL_EMIT_COMMON;
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ecb.outf = common_outf;
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res->ptr = ptr;
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res->size = 0;
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ecb.priv = res;
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return xdi_diff(f1, f2, &xpp, &xecfg, &ecb);
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}
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void *merge_file(const char *path, struct blob *base, struct blob *our, struct blob *their, unsigned long *size)
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{
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void *res = NULL;
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mmfile_t f1, f2, common;
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/*
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* Removed in either branch?
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*
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* NOTE! This depends on the caller having done the
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* proper warning about removing a file that got
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* modified in the other branch!
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*/
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if (!our || !their) {
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enum object_type type;
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if (base)
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return NULL;
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if (!our)
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our = their;
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return read_sha1_file(our->object.sha1, &type, size);
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}
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if (fill_mmfile_blob(&f1, our) < 0)
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goto out_no_mmfile;
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if (fill_mmfile_blob(&f2, their) < 0)
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goto out_free_f1;
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if (base) {
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if (fill_mmfile_blob(&common, base) < 0)
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goto out_free_f2_f1;
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} else {
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if (generate_common_file(&common, &f1, &f2) < 0)
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goto out_free_f2_f1;
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}
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res = three_way_filemerge(path, &common, &f1, &f2, size);
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free_mmfile(&common);
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out_free_f2_f1:
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free_mmfile(&f2);
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out_free_f1:
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free_mmfile(&f1);
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out_no_mmfile:
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return res;
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}
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