Revision d699676dda5fdf0996601006c3bac2a9c077a862 authored by Linus Torvalds on 10 August 2007, 19:31:20 UTC, committed by Junio C Hamano on 10 August 2007, 21:00:25 UTC
This trivially optimizes the two-way merge case of git-read-tree too, which affects switching branches. When you have tons and tons of files in your repository, but there are only small differences in the branches (maybe just a couple of files changed), the biggest cost of the branch switching was actually just the index calculations. This fixes it (timings for switching between the "testing" and "master" branches in the 100,000 file testing-repo-from-hell, where the branches only differ in one small file). Before: [torvalds@woody bummer]$ time git checkout master real 0m9.919s user 0m8.461s sys 0m0.264s After: [torvalds@woody bummer]$ time git checkout testing real 0m0.576s user 0m0.348s sys 0m0.228s so it's easily an order of magnitude different. This concludes the series. I think we could/should do the three-way merge too (to speed up merges), but I'm lazy. Somebody else can do it. The rule is very simple: you need to remove the old entry if: - you want to remove the file entirely - you replace it with a "merge conflict" entry (ie a non-stage-0 entry) and you can avoid removing it if you either - keep the old one - or resolve it to a new one. and these rules should all be valid for the three-way case too. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>
1 parent 288f072
base85.c
#include "cache.h"
#undef DEBUG_85
#ifdef DEBUG_85
#define say(a) fprintf(stderr, a)
#define say1(a,b) fprintf(stderr, a, b)
#define say2(a,b,c) fprintf(stderr, a, b, c)
#else
#define say(a) do {} while(0)
#define say1(a,b) do {} while(0)
#define say2(a,b,c) do {} while(0)
#endif
static const char en85[] = {
'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J',
'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T',
'U', 'V', 'W', 'X', 'Y', 'Z',
'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j',
'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't',
'u', 'v', 'w', 'x', 'y', 'z',
'!', '#', '$', '%', '&', '(', ')', '*', '+', '-',
';', '<', '=', '>', '?', '@', '^', '_', '`', '{',
'|', '}', '~'
};
static char de85[256];
static void prep_base85(void)
{
int i;
if (de85['Z'])
return;
for (i = 0; i < ARRAY_SIZE(en85); i++) {
int ch = en85[i];
de85[ch] = i + 1;
}
}
int decode_85(char *dst, const char *buffer, int len)
{
prep_base85();
say2("decode 85 <%.*s>", len/4*5, buffer);
while (len) {
unsigned acc = 0;
int de, cnt = 4;
unsigned char ch;
do {
ch = *buffer++;
de = de85[ch];
if (--de < 0)
return error("invalid base85 alphabet %c", ch);
acc = acc * 85 + de;
} while (--cnt);
ch = *buffer++;
de = de85[ch];
if (--de < 0)
return error("invalid base85 alphabet %c", ch);
/*
* Detect overflow. The largest
* 5-letter possible is "|NsC0" to
* encode 0xffffffff, and "|NsC" gives
* 0x03030303 at this point (i.e.
* 0xffffffff = 0x03030303 * 85).
*/
if (0x03030303 < acc ||
0xffffffff - de < (acc *= 85))
return error("invalid base85 sequence %.5s", buffer-5);
acc += de;
say1(" %08x", acc);
cnt = (len < 4) ? len : 4;
len -= cnt;
do {
acc = (acc << 8) | (acc >> 24);
*dst++ = acc;
} while (--cnt);
}
say("\n");
return 0;
}
void encode_85(char *buf, const unsigned char *data, int bytes)
{
prep_base85();
say("encode 85");
while (bytes) {
unsigned acc = 0;
int cnt;
for (cnt = 24; cnt >= 0; cnt -= 8) {
int ch = *data++;
acc |= ch << cnt;
if (--bytes == 0)
break;
}
say1(" %08x", acc);
for (cnt = 4; cnt >= 0; cnt--) {
int val = acc % 85;
acc /= 85;
buf[cnt] = en85[val];
}
buf += 5;
}
say("\n");
*buf = 0;
}
#ifdef DEBUG_85
int main(int ac, char **av)
{
char buf[1024];
if (!strcmp(av[1], "-e")) {
int len = strlen(av[2]);
encode_85(buf, av[2], len);
if (len <= 26) len = len + 'A' - 1;
else len = len + 'a' - 26 + 1;
printf("encoded: %c%s\n", len, buf);
return 0;
}
if (!strcmp(av[1], "-d")) {
int len = *av[2];
if ('A' <= len && len <= 'Z') len = len - 'A' + 1;
else len = len - 'a' + 26 + 1;
decode_85(buf, av[2]+1, len);
printf("decoded: %.*s\n", len, buf);
return 0;
}
if (!strcmp(av[1], "-t")) {
char t[4] = { -1,-1,-1,-1 };
encode_85(buf, t, 4);
printf("encoded: D%s\n", buf);
return 0;
}
}
#endif
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