Mercurial > hg
view mercurial/bdiff.c @ 13749:8bb03283e9b9
test-commit-multiple.t: improve committwice.py
- fix bug in replacebyte: parameter fn wasn't used (no harm done)
- remove unneeded matcher
- remove unused local n
- increase test coverage a bit with a second file and some sleeping
- show files changed in revisions
- move print statements out of racy path to make sure it's as racy as possible
author | Adrian Buehlmann <adrian@cadifra.com> |
---|---|
date | Wed, 23 Mar 2011 22:58:40 +0100 |
parents | afe9269dccec |
children | 73015301db86 |
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/* bdiff.c - efficient binary diff extension for Mercurial Copyright 2005, 2006 Matt Mackall <mpm@selenic.com> This software may be used and distributed according to the terms of the GNU General Public License, incorporated herein by reference. Based roughly on Python difflib */ #include <Python.h> #include <stdlib.h> #include <string.h> #include <limits.h> #if defined __hpux || defined __SUNPRO_C || defined _AIX #define inline #endif #ifdef __linux #define inline __inline #endif #ifdef _WIN32 #ifdef _MSC_VER #define inline __inline typedef unsigned long uint32_t; #else #include <stdint.h> #endif static uint32_t htonl(uint32_t x) { return ((x & 0x000000ffUL) << 24) | ((x & 0x0000ff00UL) << 8) | ((x & 0x00ff0000UL) >> 8) | ((x & 0xff000000UL) >> 24); } #else #include <sys/types.h> #if defined __BEOS__ && !defined __HAIKU__ #include <ByteOrder.h> #else #include <arpa/inet.h> #endif #include <inttypes.h> #endif #include "util.h" struct line { int hash, len, n, e; const char *l; }; struct pos { int pos, len; }; struct hunk; struct hunk { int a1, a2, b1, b2; struct hunk *next; }; static int splitlines(const char *a, int len, struct line **lr) { unsigned hash; int i; const char *p, *b = a; const char * const plast = a + len - 1; struct line *l; /* count the lines */ i = 1; /* extra line for sentinel */ for (p = a; p < a + len; p++) if (*p == '\n' || p == plast) i++; *lr = l = (struct line *)malloc(sizeof(struct line) * i); if (!l) return -1; /* build the line array and calculate hashes */ hash = 0; for (p = a; p < a + len; p++) { /* Leonid Yuriev's hash */ hash = (hash * 1664525) + (unsigned char)*p + 1013904223; if (*p == '\n' || p == plast) { l->hash = hash; hash = 0; l->len = p - b + 1; l->l = b; l->n = INT_MAX; l++; b = p + 1; } } /* set up a sentinel */ l->hash = 0; l->len = 0; l->l = a + len; return i - 1; } static inline int cmp(struct line *a, struct line *b) { return a->hash != b->hash || a->len != b->len || memcmp(a->l, b->l, a->len); } static int equatelines(struct line *a, int an, struct line *b, int bn) { int i, j, buckets = 1, t, scale; struct pos *h = NULL; /* build a hash table of the next highest power of 2 */ while (buckets < bn + 1) buckets *= 2; /* try to allocate a large hash table to avoid collisions */ for (scale = 4; scale; scale /= 2) { h = (struct pos *)malloc(scale * buckets * sizeof(struct pos)); if (h) break; } if (!h) return 0; buckets = buckets * scale - 1; /* clear the hash table */ for (i = 0; i <= buckets; i++) { h[i].pos = INT_MAX; h[i].len = 0; } /* add lines to the hash table chains */ for (i = bn - 1; i >= 0; i--) { /* find the equivalence class */ for (j = b[i].hash & buckets; h[j].pos != INT_MAX; j = (j + 1) & buckets) if (!cmp(b + i, b + h[j].pos)) break; /* add to the head of the equivalence class */ b[i].n = h[j].pos; b[i].e = j; h[j].pos = i; h[j].len++; /* keep track of popularity */ } /* compute popularity threshold */ t = (bn >= 31000) ? bn / 1000 : 1000000 / (bn + 1); /* match items in a to their equivalence class in b */ for (i = 0; i < an; i++) { /* find the equivalence class */ for (j = a[i].hash & buckets; h[j].pos != INT_MAX; j = (j + 1) & buckets) if (!cmp(a + i, b + h[j].pos)) break; a[i].e = j; /* use equivalence class for quick compare */ if (h[j].len <= t) a[i].n = h[j].pos; /* point to head of match list */ else a[i].n = INT_MAX; /* too popular */ } /* discard hash tables */ free(h); return 1; } static int longest_match(struct line *a, struct line *b, struct pos *pos, int a1, int a2, int b1, int b2, int *omi, int *omj) { int mi = a1, mj = b1, mk = 0, mb = 0, i, j, k; for (i = a1; i < a2; i++) { /* skip things before the current block */ for (j = a[i].n; j < b1; j = b[j].n) ; /* loop through all lines match a[i] in b */ for (; j < b2; j = b[j].n) { /* does this extend an earlier match? */ if (i > a1 && j > b1 && pos[j - 1].pos == i - 1) k = pos[j - 1].len + 1; else k = 1; pos[j].pos = i; pos[j].len = k; /* best match so far? */ if (k > mk) { mi = i; mj = j; mk = k; } } } if (mk) { mi = mi - mk + 1; mj = mj - mk + 1; } /* expand match to include neighboring popular lines */ while (mi - mb > a1 && mj - mb > b1 && a[mi - mb - 1].e == b[mj - mb - 1].e) mb++; while (mi + mk < a2 && mj + mk < b2 && a[mi + mk].e == b[mj + mk].e) mk++; *omi = mi - mb; *omj = mj - mb; return mk + mb; } static struct hunk *recurse(struct line *a, struct line *b, struct pos *pos, int a1, int a2, int b1, int b2, struct hunk *l) { int i, j, k; while (1) { /* find the longest match in this chunk */ k = longest_match(a, b, pos, a1, a2, b1, b2, &i, &j); if (!k) return l; /* and recurse on the remaining chunks on either side */ l = recurse(a, b, pos, a1, i, b1, j, l); if (!l) return NULL; l->next = (struct hunk *)malloc(sizeof(struct hunk)); if (!l->next) return NULL; l = l->next; l->a1 = i; l->a2 = i + k; l->b1 = j; l->b2 = j + k; l->next = NULL; /* tail-recursion didn't happen, so do equivalent iteration */ a1 = i + k; b1 = j + k; } } static int diff(struct line *a, int an, struct line *b, int bn, struct hunk *base) { struct hunk *curr; struct pos *pos; int t, count = 0; /* allocate and fill arrays */ t = equatelines(a, an, b, bn); pos = (struct pos *)calloc(bn ? bn : 1, sizeof(struct pos)); if (pos && t) { /* generate the matching block list */ curr = recurse(a, b, pos, 0, an, 0, bn, base); if (!curr) return -1; /* sentinel end hunk */ curr->next = (struct hunk *)malloc(sizeof(struct hunk)); if (!curr->next) return -1; curr = curr->next; curr->a1 = curr->a2 = an; curr->b1 = curr->b2 = bn; curr->next = NULL; } free(pos); /* normalize the hunk list, try to push each hunk towards the end */ for (curr = base->next; curr; curr = curr->next) { struct hunk *next = curr->next; int shift = 0; if (!next) break; if (curr->a2 == next->a1) while (curr->a2 + shift < an && curr->b2 + shift < bn && !cmp(a + curr->a2 + shift, b + curr->b2 + shift)) shift++; else if (curr->b2 == next->b1) while (curr->b2 + shift < bn && curr->a2 + shift < an && !cmp(b + curr->b2 + shift, a + curr->a2 + shift)) shift++; if (!shift) continue; curr->b2 += shift; next->b1 += shift; curr->a2 += shift; next->a1 += shift; } for (curr = base->next; curr; curr = curr->next) count++; return count; } static void freehunks(struct hunk *l) { struct hunk *n; for (; l; l = n) { n = l->next; free(l); } } static PyObject *blocks(PyObject *self, PyObject *args) { PyObject *sa, *sb, *rl = NULL, *m; struct line *a, *b; struct hunk l, *h; int an, bn, count, pos = 0; if (!PyArg_ParseTuple(args, "SS:bdiff", &sa, &sb)) return NULL; an = splitlines(PyBytes_AsString(sa), PyBytes_Size(sa), &a); bn = splitlines(PyBytes_AsString(sb), PyBytes_Size(sb), &b); if (!a || !b) goto nomem; l.next = NULL; count = diff(a, an, b, bn, &l); if (count < 0) goto nomem; rl = PyList_New(count); if (!rl) goto nomem; for (h = l.next; h; h = h->next) { m = Py_BuildValue("iiii", h->a1, h->a2, h->b1, h->b2); PyList_SetItem(rl, pos, m); pos++; } nomem: free(a); free(b); freehunks(l.next); return rl ? rl : PyErr_NoMemory(); } static PyObject *bdiff(PyObject *self, PyObject *args) { char *sa, *sb; PyObject *result = NULL; struct line *al, *bl; struct hunk l, *h; char encode[12], *rb; int an, bn, len = 0, la, lb, count; if (!PyArg_ParseTuple(args, "s#s#:bdiff", &sa, &la, &sb, &lb)) return NULL; an = splitlines(sa, la, &al); bn = splitlines(sb, lb, &bl); if (!al || !bl) goto nomem; l.next = NULL; count = diff(al, an, bl, bn, &l); if (count < 0) goto nomem; /* calculate length of output */ la = lb = 0; for (h = l.next; h; h = h->next) { if (h->a1 != la || h->b1 != lb) len += 12 + bl[h->b1].l - bl[lb].l; la = h->a2; lb = h->b2; } result = PyBytes_FromStringAndSize(NULL, len); if (!result) goto nomem; /* build binary patch */ rb = PyBytes_AsString(result); la = lb = 0; for (h = l.next; h; h = h->next) { if (h->a1 != la || h->b1 != lb) { len = bl[h->b1].l - bl[lb].l; *(uint32_t *)(encode) = htonl(al[la].l - al->l); *(uint32_t *)(encode + 4) = htonl(al[h->a1].l - al->l); *(uint32_t *)(encode + 8) = htonl(len); memcpy(rb, encode, 12); memcpy(rb + 12, bl[lb].l, len); rb += 12 + len; } la = h->a2; lb = h->b2; } nomem: free(al); free(bl); freehunks(l.next); return result ? result : PyErr_NoMemory(); } static char mdiff_doc[] = "Efficient binary diff."; static PyMethodDef methods[] = { {"bdiff", bdiff, METH_VARARGS, "calculate a binary diff\n"}, {"blocks", blocks, METH_VARARGS, "find a list of matching lines\n"}, {NULL, NULL} }; #ifdef IS_PY3K static struct PyModuleDef bdiff_module = { PyModuleDef_HEAD_INIT, "bdiff", mdiff_doc, -1, methods }; PyMODINIT_FUNC PyInit_bdiff(void) { return PyModule_Create(&bdiff_module); } #else PyMODINIT_FUNC initbdiff(void) { Py_InitModule3("bdiff", methods, mdiff_doc); } #endif