branchcache: add a "pure topological head" fast path
In a narrow but actually quick common case, all topological heads are all on
the same branch and all open. In this case, computing the branch map is very
simple. We can quickly detect situation where this situation will not change.
So we update the V3 format to be able to express this situation and upgrade the
update code to detect we remains in that mode.
The branch cache is populated with the actual value when the branch map is
accessed, but the update_disk method can do the update without needing to
populate it.
#ifndef HG_BITMANIPULATION_H
#define HG_BITMANIPULATION_H
#include <string.h>
#include "compat.h"
/* Reads a 64 bit integer from big-endian bytes. Assumes that the data is long
enough */
static inline uint64_t getbe64(const char *c)
{
const unsigned char *d = (const unsigned char *)c;
return ((((uint64_t)d[0]) << 56) | (((uint64_t)d[1]) << 48) |
(((uint64_t)d[2]) << 40) | (((uint64_t)d[3]) << 32) |
(((uint64_t)d[4]) << 24) | (((uint64_t)d[5]) << 16) |
(((uint64_t)d[6]) << 8) | (d[7]));
}
static inline uint32_t getbe32(const char *c)
{
const unsigned char *d = (const unsigned char *)c;
return ((((uint32_t)d[0]) << 24) | (((uint32_t)d[1]) << 16) |
(((uint32_t)d[2]) << 8) | (d[3]));
}
static inline int16_t getbeint16(const char *c)
{
const unsigned char *d = (const unsigned char *)c;
return ((d[0] << 8) | (d[1]));
}
static inline uint16_t getbeuint16(const char *c)
{
const unsigned char *d = (const unsigned char *)c;
return ((d[0] << 8) | (d[1]));
}
/* Writes a 64 bit integer to bytes in a big-endian format.
Assumes that the buffer is long enough */
static inline void putbe64(uint64_t x, char *c)
{
c[0] = (x >> 56) & 0xff;
c[1] = (x >> 48) & 0xff;
c[2] = (x >> 40) & 0xff;
c[3] = (x >> 32) & 0xff;
c[4] = (x >> 24) & 0xff;
c[5] = (x >> 16) & 0xff;
c[6] = (x >> 8) & 0xff;
c[7] = (x)&0xff;
}
static inline void putbe32(uint32_t x, char *c)
{
c[0] = (x >> 24) & 0xff;
c[1] = (x >> 16) & 0xff;
c[2] = (x >> 8) & 0xff;
c[3] = (x)&0xff;
}
static inline double getbefloat64(const char *c)
{
const unsigned char *d = (const unsigned char *)c;
double ret;
int i;
uint64_t t = 0;
for (i = 0; i < 8; i++) {
t = (t << 8) + d[i];
}
memcpy(&ret, &t, sizeof(t));
return ret;
}
#endif