Optimize dirstate walking
This generally cuts the time for hg status/diff in half, from 2s down to 1s.
The main parts I'm trying to optimize are:
1) os.walk stats every file. dirstate.changes then stats every file again.
2) os.walk yields every file and subdir to dirstate.traverse who yields every
file and everything in the dirstate map. dirstate.walk then
filters this mass and yields every file to the caller. There should be
fewer steps in here, and fewer duplicate strings yielded.
3) dirstate.walk runs util.unique on the results from dirstate.traverse,
even though it is also passing things through dirstate.seen to look for
duplicates.
I've turned os.walk into something hg specific that takes all the dirstate
ignore and matching rules into account. The new function also takes an
function arg (statmatch()) the caller supplies to help filter out
files it doesn't care about. dirstate.changes uses this to update state
for each file, avoiding the second stat call.
dirstate.walk is changed to turn the match function it is passed into
a statmatch function. The only real difference is that a statmatch
function takes the stat data as a second parameter. It now calls
dirstate.walkhelper, who requires a statmatch function to be passed.
This fails test-walk, but right now I think this is from a sorting error
fixed by this patch.
Index: crew/mercurial/dirstate.py
===================================================================
/*
mpatch.c - efficient binary patching for Mercurial
This implements a patch algorithm that's O(m + nlog n) where m is the
size of the output and n is the number of patches.
Given a list of binary patches, it unpacks each into a hunk list,
then combines the hunk lists with a treewise recursion to form a
single hunk list. This hunk list is then applied to the original
text.
The text (or binary) fragments are copied directly from their source
Python objects into a preallocated output string to avoid the
allocation of intermediate Python objects. Working memory is about 2x
the total number of hunks.
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.
*/
#include <Python.h>
#include <stdlib.h>
#include <string.h>
#ifdef _WIN32
#ifdef _MSC_VER
#define inline __inline
typedef unsigned long uint32_t;
#else
#include <stdint.h>
#endif
static uint32_t ntohl(uint32_t x)
{
return ((x & 0x000000ffUL) << 24) |
((x & 0x0000ff00UL) << 8) |
((x & 0x00ff0000UL) >> 8) |
((x & 0xff000000UL) >> 24);
}
#else
#include <sys/types.h>
#include <arpa/inet.h>
#endif
static char mpatch_doc[] = "Efficient binary patching.";
struct frag {
int start, end, len;
char *data;
};
struct flist {
struct frag *base, *head, *tail;
};
static struct flist *lalloc(int size)
{
struct flist *a = NULL;
a = malloc(sizeof(struct flist));
if (a) {
a->base = malloc(sizeof(struct frag) * size);
if (!a->base) {
free(a);
a = NULL;
} else
a->head = a->tail = a->base;
}
return a;
}
static void lfree(struct flist *a)
{
if (a) {
free(a->base);
free(a);
}
}
static int lsize(struct flist *a)
{
return a->tail - a->head;
}
/* move hunks in source that are less cut to dest, compensating
for changes in offset. the last hunk may be split if necessary.
*/
static int gather(struct flist *dest, struct flist *src, int cut, int offset)
{
struct frag *d = dest->tail, *s = src->head;
int postend, c, l;
while (s != src->tail) {
if (s->start + offset >= cut)
break; /* we've gone far enough */
postend = offset + s->start + s->len;
if (postend <= cut) {
/* save this hunk */
offset += s->start + s->len - s->end;
*d++ = *s++;
}
else {
/* break up this hunk */
c = cut - offset;
if (s->end < c)
c = s->end;
l = cut - offset - s->start;
if (s->len < l)
l = s->len;
offset += s->start + l - c;
d->start = s->start;
d->end = c;
d->len = l;
d->data = s->data;
d++;
s->start = c;
s->len = s->len - l;
s->data = s->data + l;
break;
}
}
dest->tail = d;
src->head = s;
return offset;
}
/* like gather, but with no output list */
static int discard(struct flist *src, int cut, int offset)
{
struct frag *s = src->head;
int postend, c, l;
while (s != src->tail) {
if (s->start + offset >= cut)
break;
postend = offset + s->start + s->len;
if (postend <= cut) {
offset += s->start + s->len - s->end;
s++;
}
else {
c = cut - offset;
if (s->end < c)
c = s->end;
l = cut - offset - s->start;
if (s->len < l)
l = s->len;
offset += s->start + l - c;
s->start = c;
s->len = s->len - l;
s->data = s->data + l;
break;
}
}
src->head = s;
return offset;
}
/* combine hunk lists a and b, while adjusting b for offset changes in a/
this deletes a and b and returns the resultant list. */
static struct flist *combine(struct flist *a, struct flist *b)
{
struct flist *c = NULL;
struct frag *bh, *ct;
int offset = 0, post;
if (a && b)
c = lalloc((lsize(a) + lsize(b)) * 2);
if (c) {
for (bh = b->head; bh != b->tail; bh++) {
/* save old hunks */
offset = gather(c, a, bh->start, offset);
/* discard replaced hunks */
post = discard(a, bh->end, offset);
/* insert new hunk */
ct = c->tail;
ct->start = bh->start - offset;
ct->end = bh->end - post;
ct->len = bh->len;
ct->data = bh->data;
c->tail++;
offset = post;
}
/* hold on to tail from a */
memcpy(c->tail, a->head, sizeof(struct frag) * lsize(a));
c->tail += lsize(a);
}
lfree(a);
lfree(b);
return c;
}
/* decode a binary patch into a hunk list */
static struct flist *decode(char *bin, int len)
{
struct flist *l;
struct frag *lt;
char *end = bin + len;
char decode[12]; /* for dealing with alignment issues */
/* assume worst case size, we won't have many of these lists */
l = lalloc(len / 12);
lt = l->tail;
while (bin < end) {
memcpy(decode, bin, 12);
lt->start = ntohl(*(uint32_t *)decode);
lt->end = ntohl(*(uint32_t *)(decode + 4));
lt->len = ntohl(*(uint32_t *)(decode + 8));
lt->data = bin + 12;
bin += 12 + lt->len;
lt++;
}
l->tail = lt;
return l;
}
/* calculate the size of resultant text */
static int calcsize(int len, struct flist *l)
{
int outlen = 0, last = 0;
struct frag *f = l->head;
while (f != l->tail) {
outlen += f->start - last;
last = f->end;
outlen += f->len;
f++;
}
outlen += len - last;
return outlen;
}
static void apply(char *buf, char *orig, int len, struct flist *l)
{
struct frag *f = l->head;
int last = 0;
char *p = buf;
while (f != l->tail) {
memcpy(p, orig + last, f->start - last);
p += f->start - last;
memcpy(p, f->data, f->len);
last = f->end;
p += f->len;
f++;
}
memcpy(p, orig + last, len - last);
}
/* recursively generate a patch of all bins between start and end */
static struct flist *fold(PyObject *bins, int start, int end)
{
int len;
if (start + 1 == end) {
/* trivial case, output a decoded list */
PyObject *tmp = PyList_GetItem(bins, start);
if (!tmp)
return NULL;
return decode(PyString_AsString(tmp), PyString_Size(tmp));
}
/* divide and conquer, memory management is elsewhere */
len = (end - start) / 2;
return combine(fold(bins, start, start + len),
fold(bins, start + len, end));
}
static PyObject *
patches(PyObject *self, PyObject *args)
{
PyObject *text, *bins, *result;
struct flist *patch;
char *in, *out;
int len, outlen;
if (!PyArg_ParseTuple(args, "SO:mpatch", &text, &bins))
return NULL;
len = PyList_Size(bins);
if (!len) {
/* nothing to do */
Py_INCREF(text);
return text;
}
patch = fold(bins, 0, len);
if (!patch)
return PyErr_NoMemory();
outlen = calcsize(PyString_Size(text), patch);
result = PyString_FromStringAndSize(NULL, outlen);
if (result) {
in = PyString_AsString(text);
out = PyString_AsString(result);
apply(out, in, PyString_Size(text), patch);
}
lfree(patch);
return result;
}
static PyMethodDef methods[] = {
{"patches", patches, METH_VARARGS, "apply a series of patches\n"},
{NULL, NULL}
};
PyMODINIT_FUNC
initmpatch(void)
{
Py_InitModule3("mpatch", methods, mpatch_doc);
}