Mercurial > hg
view mercurial/bdiff.c @ 460:6409d9a0df43
add dirstate debugging commands
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add dirstate debugging commands
As I've played with various different merges and more recently
rawcommit, I've found the following patch to be very very helpful in
figuring out whether the dirstate is being left in a consistent or
inconsistent state with respect to the current manifest.
I attempted to deduce the invariants that were assumed by the current
code, and then check it in this code.
I may or may not have captured the design intent in this check; if not,
I'd be very happy to hear more clearly what was intended, so that I can
write tests to that expectation.
Anyway, here's the patch. Not sure if it's a good idea to commit it to
the mainline, or just leave it as a debugging aid. I attempted to
package it so that it doesn't interfere with normal usage.
Michael Fetterman
(tweaked by mpm: remove -d magic)
manifest hash: 869f5b5f954dc0f46ba27322359e811d5e21d71c
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author | mpm@selenic.com |
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date | Fri, 24 Jun 2005 22:51:39 -0800 |
parents | f81a011fba3d |
children | ea93402b81b9 50da4bb9cab6 |
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/* bdiff.c - efficient binary diff extension for Mercurial Copyright 2005 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> #ifdef _WIN32 typedef unsigned long uint32_t; static uint32_t htonl(uint32_t x) { return ((x & 0x000000ffUL) << 24) | ((x & 0x0000ff00UL) << 8) | ((x & 0x00ff0000UL) >> 8) | ((x & 0xff000000UL) >> 24); } #else #include <netinet/in.h> #include <sys/types.h> #endif struct line { int h, len, n, e; const char *l; }; struct hunk { int a1, a2, b1, b2; }; struct hunklist { struct hunk *base, *head; }; static __inline uint32_t rol32(uint32_t word, unsigned int shift) { return (word << shift) | (word >> (32 - shift)); } int splitlines(const char *a, int len, struct line **lr) { int h, i; const char *p, *b = a; struct line *l; /* count the lines */ i = 1; /* extra line for sentinel */ for (p = a; p < a + len; p++) if (*p == '\n' || p == a + len - 1) i++; *lr = l = malloc(sizeof(struct line) * i); if (!l) return -1; /* build the line array and calculate hashes */ h = 0; for (p = a; p < a + len; p++) { h = *p + rol32(h, 7); /* a simple hash from GNU diff */ if (*p == '\n' || p == a + len - 1) { l->len = p - b + 1; l->h = h * l->len; l->l = b; l->n = -1; l++; b = p + 1; h = 0; } } /* set up a sentinel */ l->h = l->len = 0; l->l = a + len; return i - 1; } int inline cmp(struct line *a, struct line *b) { return a->h != b->h || 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, *h, *l; /* build a hash table of the next highest power of 2 */ while (buckets < bn + 1) buckets *= 2; h = malloc(buckets * sizeof(int)); l = calloc(buckets, sizeof(int)); buckets = buckets - 1; if (!h || !l) { free(h); return 0; } /* clear the hash table */ for (i = 0; i <= buckets; i++) h[i] = -1; /* add lines to the hash table chains */ for (i = bn - 1; i >= 0; i--) { /* find the equivalence class */ for (j = b[i].h & buckets; h[j] != -1; j = (j + 1) & buckets) if (!cmp(b + i, b + h[j])) break; /* add to the head of the equivalence class */ b[i].n = h[j]; b[i].e = j; h[j] = i; l[j]++; /* keep track of popularity */ } /* compute popularity threshold */ t = (bn >= 200) ? bn / 100 : 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].h & buckets; h[j] != -1; j = (j + 1) & buckets) if (!cmp(a + i, b + h[j])) break; a[i].e = j; /* use equivalence class for quick compare */ if(l[j] <= t) a[i].n = h[j]; /* point to head of match list */ else a[i].n = -1; /* too popular */ } /* discard hash tables */ free(h); free(l); return 1; } static int longest_match(struct line *a, struct line *b, int *jpos, int *jlen, 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 != -1 && j < b1; j = b[j].n) ; /* loop through all lines match a[i] in b */ for (; j != -1 && j < b2; j = b[j].n) { /* does this extend an earlier match? */ if (i > a1 && j > b1 && jpos[j - 1] == i - 1) k = jlen[j - 1] + 1; else k = 1; jpos[j] = i; jlen[j] = 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 void recurse(struct line *a, struct line *b, int *jpos, int *jlen, int a1, int a2, int b1, int b2, struct hunklist *l) { int i, j, k; /* find the longest match in this chunk */ k = longest_match(a, b, jpos, jlen, a1, a2, b1, b2, &i, &j); if (!k) return; /* and recurse on the remaining chunks on either side */ recurse(a, b, jpos, jlen, a1, i, b1, j, l); l->head->a1 = i; l->head->a2 = i + k; l->head->b1 = j; l->head->b2 = j + k; l->head++; recurse(a, b, jpos, jlen, i + k, a2, j + k, b2, l); } static struct hunklist diff(struct line *a, int an, struct line *b, int bn) { struct hunklist l; int *jpos, *jlen, t; /* allocate and fill arrays */ t = equatelines(a, an, b, bn); jpos = calloc(bn, sizeof(int)); jlen = calloc(bn, sizeof(int)); l.head = l.base = malloc(sizeof(struct hunk) * ((an + bn) / 4 + 2)); if (jpos && jlen && l.base && t) { /* generate the matching block list */ recurse(a, b, jpos, jlen, 0, an, 0, bn, &l); l.head->a1 = an; l.head->b1 = bn; l.head++; } free(jpos); free(jlen); return l; } static PyObject *blocks(PyObject *self, PyObject *args) { PyObject *sa, *sb, *rl = NULL, *m; struct line *a, *b; struct hunklist l; struct hunk *h; int an, bn, pos = 0; if (!PyArg_ParseTuple(args, "SS:bdiff", &sa, &sb)) return NULL; an = splitlines(PyString_AsString(sa), PyString_Size(sa), &a); bn = splitlines(PyString_AsString(sb), PyString_Size(sb), &b); if (!a || !b) goto nomem; l = diff(a, an, b, bn); rl = PyList_New(l.head - l.base); if (!l.head || !rl) goto nomem; for(h = l.base; h != l.head; h++) { m = Py_BuildValue("iiii", h->a1, h->a2, h->b1, h->b2); PyList_SetItem(rl, pos, m); pos++; } nomem: free(a); free(b); free(l.base); return rl ? rl : PyErr_NoMemory(); } static PyObject *bdiff(PyObject *self, PyObject *args) { PyObject *sa, *sb, *result = NULL; struct line *al, *bl; struct hunklist l; struct hunk *h; char encode[12], *rb; int an, bn, len = 0, la = 0, lb = 0; if (!PyArg_ParseTuple(args, "SS:bdiff", &sa, &sb)) return NULL; an = splitlines(PyString_AsString(sa), PyString_Size(sa), &al); bn = splitlines(PyString_AsString(sb), PyString_Size(sb), &bl); if (!al || !bl) goto nomem; l = diff(al, an, bl, bn); if (!l.head) goto nomem; /* calculate length of output */ for(h = l.base; h != l.head; h++) { if (h->a1 != la || h->b1 != lb) len += 12 + bl[h->b1].l - bl[lb].l; la = h->a2; lb = h->b2; } result = PyString_FromStringAndSize(NULL, len); if (!result) goto nomem; /* build binary patch */ rb = PyString_AsString(result); la = lb = 0; for(h = l.base; h != l.head; h++) { 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); free(l.base); 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} }; PyMODINIT_FUNC initbdiff(void) { Py_InitModule3("bdiff", methods, mdiff_doc); }