upstream/mercurial-mirror Files · mercurial/cffi/mpatch.py

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.

Jun Wu - - Load All Authors

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                r31587:ed5b2587

4.1.2 stable

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             mpatch.py
        
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      from __future__ import absolute_import

      import cffi

      import os

      ffi = cffi.FFI()

      mpatch_c = os.path.join(os.path.join(os.path.dirname(__file__), '..',

                                           'mpatch.c'))

      ffi.set_source("_mpatch_cffi", open(mpatch_c).read(),

                     include_dirs=["mercurial"])

      ffi.cdef("""

      struct mpatch_frag {

             int start, end, len;

             const char *data;

      };

      struct mpatch_flist {

             struct mpatch_frag *base, *head, *tail;

      };

      extern "Python" struct mpatch_flist* cffi_get_next_item(void*, ssize_t);

      int mpatch_decode(const char *bin, ssize_t len, struct mpatch_flist** res);

      ssize_t mpatch_calcsize(size_t len, struct mpatch_flist *l);

      void mpatch_lfree(struct mpatch_flist *a);

      static int mpatch_apply(char *buf, const char *orig, size_t len,

                              struct mpatch_flist *l);

      struct mpatch_flist *mpatch_fold(void *bins,

                             struct mpatch_flist* (*get_next_item)(void*, ssize_t),

                             ssize_t start, ssize_t end);

      """)

      if __name__ == '__main__':

          ffi.compile()

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				from __future__ import absolute_import

				import cffi
				import os

				ffi = cffi.FFI()
				mpatch_c = os.path.join(os.path.join(os.path.dirname(__file__), '..',
				'mpatch.c'))
				ffi.set_source("_mpatch_cffi", open(mpatch_c).read(),
				include_dirs=["mercurial"])
				ffi.cdef("""

				struct mpatch_frag {
				int start, end, len;
				const char *data;
				};

				struct mpatch_flist {
				struct mpatch_frag base, head, *tail;
				};

				extern "Python" struct mpatch_flist* cffi_get_next_item(void*, ssize_t);

				int mpatch_decode(const char bin, ssize_t len, struct mpatch_flist* res);
				ssize_t mpatch_calcsize(size_t len, struct mpatch_flist *l);
				void mpatch_lfree(struct mpatch_flist *a);
				static int mpatch_apply(char buf, const char orig, size_t len,
				struct mpatch_flist *l);
				struct mpatch_flist mpatch_fold(void bins,
				struct mpatch_flist* (get_next_item)(void, ssize_t),
				ssize_t start, ssize_t end);
				""")

				if __name__ == '__main__':
				ffi.compile()