1d848f643c
In addition to optimizing pathspecs that would never match, which was done earlier, this optimizes pathspecs that would always match (e.g. "arch/" while the traversal is already in "arch/i386/" hierarchy). This patch makes the worst case slightly more palatable, while improving average case. Signed-off-by: Junio C Hamano <junkio@cox.net>
365 lines
8.7 KiB
C
365 lines
8.7 KiB
C
/*
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* Helper functions for tree diff generation
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*/
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#include "cache.h"
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#include "diff.h"
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#include "tree.h"
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static char *malloc_base(const char *base, int baselen, const char *path, int pathlen)
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{
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char *newbase = xmalloc(baselen + pathlen + 2);
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memcpy(newbase, base, baselen);
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memcpy(newbase + baselen, path, pathlen);
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memcpy(newbase + baselen + pathlen, "/", 2);
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return newbase;
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}
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static void show_entry(struct diff_options *opt, const char *prefix, struct tree_desc *desc,
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const char *base, int baselen);
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static int compare_tree_entry(struct tree_desc *t1, struct tree_desc *t2, const char *base, int baselen, struct diff_options *opt)
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{
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unsigned mode1, mode2;
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const char *path1, *path2;
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const unsigned char *sha1, *sha2;
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int cmp, pathlen1, pathlen2;
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sha1 = tree_entry_extract(t1, &path1, &mode1);
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sha2 = tree_entry_extract(t2, &path2, &mode2);
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pathlen1 = tree_entry_len(path1, sha1);
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pathlen2 = tree_entry_len(path2, sha2);
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cmp = base_name_compare(path1, pathlen1, mode1, path2, pathlen2, mode2);
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if (cmp < 0) {
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show_entry(opt, "-", t1, base, baselen);
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return -1;
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}
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if (cmp > 0) {
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show_entry(opt, "+", t2, base, baselen);
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return 1;
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}
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if (!opt->find_copies_harder && !hashcmp(sha1, sha2) && mode1 == mode2)
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return 0;
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/*
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* If the filemode has changed to/from a directory from/to a regular
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* file, we need to consider it a remove and an add.
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*/
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if (S_ISDIR(mode1) != S_ISDIR(mode2)) {
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show_entry(opt, "-", t1, base, baselen);
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show_entry(opt, "+", t2, base, baselen);
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return 0;
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}
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if (opt->recursive && S_ISDIR(mode1)) {
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int retval;
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char *newbase = malloc_base(base, baselen, path1, pathlen1);
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if (opt->tree_in_recursive)
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opt->change(opt, mode1, mode2,
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sha1, sha2, base, path1);
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retval = diff_tree_sha1(sha1, sha2, newbase, opt);
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free(newbase);
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return retval;
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}
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opt->change(opt, mode1, mode2, sha1, sha2, base, path1);
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return 0;
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}
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/*
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* Is a tree entry interesting given the pathspec we have?
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*
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* Return:
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* - 2 for "yes, and all subsequent entries will be"
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* - 1 for yes
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* - zero for no
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* - negative for "no, and no subsequent entries will be either"
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*/
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static int tree_entry_interesting(struct tree_desc *desc, const char *base, int baselen, struct diff_options *opt)
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{
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const char *path;
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const unsigned char *sha1;
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unsigned mode;
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int i;
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int pathlen;
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int never_interesting = -1;
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if (!opt->nr_paths)
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return 1;
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sha1 = tree_entry_extract(desc, &path, &mode);
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pathlen = tree_entry_len(path, sha1);
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for (i = 0; i < opt->nr_paths; i++) {
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const char *match = opt->paths[i];
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int matchlen = opt->pathlens[i];
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int m = -1; /* signals that we haven't called strncmp() */
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if (baselen >= matchlen) {
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/* If it doesn't match, move along... */
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if (strncmp(base, match, matchlen))
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continue;
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/*
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* The base is a subdirectory of a path which
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* was specified, so all of them are interesting.
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*/
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return 2;
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}
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/* Does the base match? */
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if (strncmp(base, match, baselen))
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continue;
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match += baselen;
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matchlen -= baselen;
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if (never_interesting) {
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/*
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* We have not seen any match that sorts later
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* than the current path.
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*/
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/*
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* Does match sort strictly earlier than path
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* with their common parts?
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*/
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m = strncmp(match, path,
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(matchlen < pathlen) ? matchlen : pathlen);
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if (m < 0)
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continue;
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/*
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* If we come here even once, that means there is at
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* least one pathspec that would sort equal to or
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* later than the path we are currently looking at.
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* In other words, if we have never reached this point
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* after iterating all pathspecs, it means all
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* pathspecs are either outside of base, or inside the
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* base but sorts strictly earlier than the current
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* one. In either case, they will never match the
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* subsequent entries. In such a case, we initialized
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* the variable to -1 and that is what will be
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* returned, allowing the caller to terminate early.
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*/
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never_interesting = 0;
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}
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if (pathlen > matchlen)
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continue;
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if (matchlen > pathlen) {
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if (match[pathlen] != '/')
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continue;
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if (!S_ISDIR(mode))
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continue;
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}
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if (m == -1)
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/*
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* we cheated and did not do strncmp(), so we do
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* that here.
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*/
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m = strncmp(match, path, pathlen);
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/*
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* If common part matched earlier then it is a hit,
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* because we rejected the case where path is not a
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* leading directory and is shorter than match.
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*/
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if (!m)
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return 1;
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}
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return never_interesting; /* No matches */
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}
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/* A whole sub-tree went away or appeared */
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static void show_tree(struct diff_options *opt, const char *prefix, struct tree_desc *desc, const char *base, int baselen)
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{
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int all_interesting = 0;
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while (desc->size) {
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int show;
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if (all_interesting)
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show = 1;
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else {
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show = tree_entry_interesting(desc, base, baselen,
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opt);
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if (show == 2)
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all_interesting = 1;
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}
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if (show < 0)
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break;
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if (show)
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show_entry(opt, prefix, desc, base, baselen);
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update_tree_entry(desc);
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}
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}
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/* A file entry went away or appeared */
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static void show_entry(struct diff_options *opt, const char *prefix, struct tree_desc *desc,
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const char *base, int baselen)
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{
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unsigned mode;
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const char *path;
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const unsigned char *sha1 = tree_entry_extract(desc, &path, &mode);
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if (opt->recursive && S_ISDIR(mode)) {
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enum object_type type;
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int pathlen = tree_entry_len(path, sha1);
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char *newbase = malloc_base(base, baselen, path, pathlen);
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struct tree_desc inner;
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void *tree;
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unsigned long size;
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tree = read_sha1_file(sha1, &type, &size);
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if (!tree || type != OBJ_TREE)
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die("corrupt tree sha %s", sha1_to_hex(sha1));
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init_tree_desc(&inner, tree, size);
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show_tree(opt, prefix, &inner, newbase, baselen + 1 + pathlen);
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free(tree);
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free(newbase);
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} else {
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opt->add_remove(opt, prefix[0], mode, sha1, base, path);
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}
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}
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static void skip_uninteresting(struct tree_desc *t, const char *base, int baselen, struct diff_options *opt)
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{
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int all_interesting = 0;
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while (t->size) {
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int show;
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if (all_interesting)
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show = 1;
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else {
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show = tree_entry_interesting(t, base, baselen, opt);
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if (show == 2)
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all_interesting = 1;
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}
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if (!show) {
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update_tree_entry(t);
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continue;
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}
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/* Skip it all? */
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if (show < 0)
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t->size = 0;
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return;
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}
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}
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int diff_tree(struct tree_desc *t1, struct tree_desc *t2, const char *base, struct diff_options *opt)
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{
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int baselen = strlen(base);
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for (;;) {
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if (opt->quiet && opt->has_changes)
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break;
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if (opt->nr_paths) {
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skip_uninteresting(t1, base, baselen, opt);
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skip_uninteresting(t2, base, baselen, opt);
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}
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if (!t1->size) {
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if (!t2->size)
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break;
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show_entry(opt, "+", t2, base, baselen);
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update_tree_entry(t2);
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continue;
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}
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if (!t2->size) {
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show_entry(opt, "-", t1, base, baselen);
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update_tree_entry(t1);
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continue;
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}
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switch (compare_tree_entry(t1, t2, base, baselen, opt)) {
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case -1:
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update_tree_entry(t1);
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continue;
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case 0:
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update_tree_entry(t1);
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/* Fallthrough */
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case 1:
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update_tree_entry(t2);
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continue;
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}
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die("git-diff-tree: internal error");
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}
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return 0;
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}
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int diff_tree_sha1(const unsigned char *old, const unsigned char *new, const char *base, struct diff_options *opt)
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{
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void *tree1, *tree2;
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struct tree_desc t1, t2;
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unsigned long size1, size2;
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int retval;
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tree1 = read_object_with_reference(old, tree_type, &size1, NULL);
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if (!tree1)
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die("unable to read source tree (%s)", sha1_to_hex(old));
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tree2 = read_object_with_reference(new, tree_type, &size2, NULL);
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if (!tree2)
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die("unable to read destination tree (%s)", sha1_to_hex(new));
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init_tree_desc(&t1, tree1, size1);
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init_tree_desc(&t2, tree2, size2);
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retval = diff_tree(&t1, &t2, base, opt);
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free(tree1);
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free(tree2);
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return retval;
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}
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int diff_root_tree_sha1(const unsigned char *new, const char *base, struct diff_options *opt)
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{
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int retval;
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void *tree;
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unsigned long size;
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struct tree_desc empty, real;
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tree = read_object_with_reference(new, tree_type, &size, NULL);
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if (!tree)
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die("unable to read root tree (%s)", sha1_to_hex(new));
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init_tree_desc(&real, tree, size);
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init_tree_desc(&empty, "", 0);
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retval = diff_tree(&empty, &real, base, opt);
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free(tree);
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return retval;
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}
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static int count_paths(const char **paths)
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{
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int i = 0;
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while (*paths++)
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i++;
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return i;
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}
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void diff_tree_release_paths(struct diff_options *opt)
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{
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free(opt->pathlens);
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}
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void diff_tree_setup_paths(const char **p, struct diff_options *opt)
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{
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opt->nr_paths = 0;
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opt->pathlens = NULL;
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opt->paths = NULL;
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if (p) {
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int i;
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opt->paths = p;
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opt->nr_paths = count_paths(p);
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if (opt->nr_paths == 0) {
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opt->pathlens = NULL;
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return;
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}
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opt->pathlens = xmalloc(opt->nr_paths * sizeof(int));
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for (i=0; i < opt->nr_paths; i++)
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opt->pathlens[i] = strlen(p[i]);
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}
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}
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