upstream/mercurial-mirror Files · mercurial/bdiff.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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                r31587:ed5b2587

4.1.2 stable

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      #ifndef _HG_BDIFF_H_

      #define _HG_BDIFF_H_

      struct bdiff_line {

      	int hash, n, e;

      	ssize_t len;

      	const char *l;

      };

      struct bdiff_hunk;

      struct bdiff_hunk {

      	int a1, a2, b1, b2;

      	struct bdiff_hunk *next;

      };

      int bdiff_splitlines(const char *a, ssize_t len, struct bdiff_line **lr);

      int bdiff_diff(struct bdiff_line *a, int an, struct bdiff_line *b, int bn,

      	struct bdiff_hunk *base);

      void bdiff_freehunks(struct bdiff_hunk *l);

      #endif

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				#ifndef _HG_BDIFF_H_
				#define _HG_BDIFF_H_

				struct bdiff_line {
				int hash, n, e;
				ssize_t len;
				const char *l;
				};

				struct bdiff_hunk;
				struct bdiff_hunk {
				int a1, a2, b1, b2;
				struct bdiff_hunk *next;
				};

				int bdiff_splitlines(const char a, ssize_t len, struct bdiff_line *lr);
				int bdiff_diff(struct bdiff_line a, int an, struct bdiff_line b, int bn,
				struct bdiff_hunk *base);
				void bdiff_freehunks(struct bdiff_hunk *l);

				#endif