upstream/mercurial-mirror Files · mercurial/bitmanipulation.h

changegroup: store old heads as a set...

changegroup: store old heads as a set Previously, the "oldheads" variable was a list. On a repository at Mozilla with 46,492 heads, profiling revealed that list membership testing was dominating execution time of applying small changegroups. This patch converts the list of old heads to a set. This makes membership testing significantly faster. On the aforementioned repository with 46,492 heads: $ hg unbundle <file with 1 changeset> before: 18.535s wall after: 1.303s Consumers of this variable only check for truthiness (`if oldheads`), length (`len(oldheads)`), and (most importantly) item membership (`h not in oldheads` - which occurs twice). So, the change to a set should be safe and suitable for stable. The practical effect of this change is that changegroup application and related operations (like `hg push`) no longer exhibit an O(n^2) CPU explosion as the number of heads grows.

Maciej Fijalkowski - - Load All Authors

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r29444:284d742e default


                r31587:ed5b2587

4.1.2 stable

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             bitmanipulation.h
        
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      #ifndef _HG_BITMANIPULATION_H_

      #define _HG_BITMANIPULATION_H_

      #include "compat.h"

      static inline uint32_t getbe32(const char *c)

      {

      	const unsigned char *d = (const unsigned char *)c;

      	return ((d[0] << 24) |

      		(d[1] << 16) |

      		(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]));

      }

      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

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				#ifndef _HG_BITMANIPULATION_H_
				#define _HG_BITMANIPULATION_H_

				#include "compat.h"

				static inline uint32_t getbe32(const char *c)
				{
				const unsigned char d = (const unsigned char )c;

				return ((d[0] << 24) \|
				(d[1] << 16) \|
				(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]));
				}

				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