upstream/mercurial-mirror Files · mercurial/thirdparty/xdiff/xdiffi.h

merge: mark file gets as not thread safe (issue5933)...

merge: mark file gets as not thread safe (issue5933) In default installs, this has the effect of disabling the thread-based worker on Windows when manifesting files in the working directory. My measurements have shown that with revlog-based repositories, Mercurial spends a lot of CPU time in revlog code resolving file data. This ends up incurring a lot of context switching across threads and slows down `hg update` operations when going from an empty working directory to the tip of the repo. On mozilla-unified (246,351 files) on an i7-6700K (4+4 CPUs): before: 487s wall after: 360s wall (equivalent to worker.enabled=false) cpus=2: 379s wall Even with only 2 threads, the thread pool is still slower. The introduction of the thread-based worker (02b36e860e0b) states that it resulted in a "~50%" speedup for `hg sparse --enable-profile` and `hg sparse --disable-profile`. This disagrees with my measurement above. I theorize a few reasons for this: 1) Removal of files from the working directory is I/O - not CPU - bound and should benefit from a thread pool (unless I/O is insanely fast and the GIL release is near instantaneous). So tests like `hg sparse --enable-profile` may exercise deletion throughput and aren't good benchmarks for worker tasks that are CPU heavy. 2) The patch was authored by someone at Facebook. The results were likely measured against a repository using remotefilelog. And I believe that revision retrieval during working directory updates with remotefilelog will often use a remote store, thus being I/O and not CPU bound. This probably resulted in an overstated performance gain. Since there appears to be a need to enable the thread-based worker with some stores, I've made the flagging of file gets as thread safe configurable. I've made it experimental because I don't want to formalize a boolean flag for this option and because this attribute is best captured against the store implementation. But we don't have a proper store API for this yet. I'd rather cross this bridge later. It is possible there are revlog-based repositories that do benefit from a thread-based worker. I didn't do very comprehensive testing. If there are, we may want to devise a more proper algorithm for whether to use the thread-based worker, including possibly config options to limit the number of threads to use. But until I see evidence that justifies complexity, simplicity wins. Differential Revision: https://phab.mercurial-scm.org/D3963

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        Jun Wu
    
xdiff: vendor xdiff library from git...

              r36689
            
      /*

       *  LibXDiff by Davide Libenzi ( File Differential Library )

       *  Copyright (C) 2003  Davide Libenzi

       *

       *  This library is free software; you can redistribute it and/or

       *  modify it under the terms of the GNU Lesser General Public

       *  License as published by the Free Software Foundation; either

       *  version 2.1 of the License, or (at your option) any later version.

       *

       *  This library is distributed in the hope that it will be useful,

       *  but WITHOUT ANY WARRANTY; without even the implied warranty of

       *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

       *  Lesser General Public License for more details.

       *

       *  You should have received a copy of the GNU Lesser General Public

       *  License along with this library; if not, see

       *  <http://www.gnu.org/licenses/>.

       *

       *  Davide Libenzi <davidel@xmailserver.org>

       *

       */

      #if !defined(XDIFFI_H)

      #define XDIFFI_H

      typedef struct s_diffdata {

        Jun Wu
    
xdiff: replace {unsigned ,}long with {u,}int64_t...

              r36840
            
      	int64_t nrec;

      	uint64_t const *ha;

      	int64_t *rindex;

        Jun Wu
    
xdiff: vendor xdiff library from git...

              r36689
            
      	char *rchg;

      } diffdata_t;

      typedef struct s_xdalgoenv {

        Jun Wu
    
xdiff: replace {unsigned ,}long with {u,}int64_t...

              r36840
            
      	int64_t mxcost;

      	int64_t snake_cnt;

      	int64_t heur_min;

        Jun Wu
    
xdiff: vendor xdiff library from git...

              r36689
            
      } xdalgoenv_t;

      typedef struct s_xdchange {

      	struct s_xdchange *next;

        Jun Wu
    
xdiff: replace {unsigned ,}long with {u,}int64_t...

              r36840
            
      	int64_t i1, i2;

      	int64_t chg1, chg2;

        Jun Wu
    
xdiff: vendor xdiff library from git...

              r36689
            
      	int ignore;

      } xdchange_t;

        Jun Wu
    
xdiff: replace {unsigned ,}long with {u,}int64_t...

              r36840
            
      int xdl_recs_cmp(diffdata_t *dd1, int64_t off1, int64_t lim1,

      		 diffdata_t *dd2, int64_t off2, int64_t lim2,

      		 int64_t *kvdf, int64_t *kvdb, int need_min, xdalgoenv_t *xenv);

        Jun Wu
    
xdiff: vendor xdiff library from git...

              r36689
            
      int xdl_do_diff(mmfile_t *mf1, mmfile_t *mf2, xpparam_t const *xpp,

      		xdfenv_t *xe);

        Jun Wu
    
xdiff: replace {unsigned ,}long with {u,}int64_t...

              r36840
            
      int xdl_change_compact(xdfile_t *xdf, xdfile_t *xdfo, int64_t flags);

        Jun Wu
    
xdiff: vendor xdiff library from git...

              r36689
            
      int xdl_build_script(xdfenv_t *xe, xdchange_t **xscr);

      void xdl_free_script(xdchange_t *xscr);

      #endif /* #if !defined(XDIFFI_H) */

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Jun Wu xdiff: vendor xdiff library from git...	r36689	/*
		* LibXDiff by Davide Libenzi ( File Differential Library )
		* Copyright (C) 2003 Davide Libenzi
		*
		* This library is free software; you can redistribute it and/or
		* modify it under the terms of the GNU Lesser General Public
		* License as published by the Free Software Foundation; either
		* version 2.1 of the License, or (at your option) any later version.
		*
		* This library is distributed in the hope that it will be useful,
		* but WITHOUT ANY WARRANTY; without even the implied warranty of
		* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
		* Lesser General Public License for more details.
		*
		* You should have received a copy of the GNU Lesser General Public
		* License along with this library; if not, see
		* <http://www.gnu.org/licenses/>.
		*
		* Davide Libenzi <davidel@xmailserver.org>
		*
		*/

		#if !defined(XDIFFI_H)
		#define XDIFFI_H


		typedef struct s_diffdata {
Jun Wu xdiff: replace {unsigned ,}long with {u,}int64_t...	r36840	int64_t nrec;
		uint64_t const *ha;
		int64_t *rindex;
Jun Wu xdiff: vendor xdiff library from git...	r36689	char *rchg;
		} diffdata_t;

		typedef struct s_xdalgoenv {
Jun Wu xdiff: replace {unsigned ,}long with {u,}int64_t...	r36840	int64_t mxcost;
		int64_t snake_cnt;
		int64_t heur_min;
Jun Wu xdiff: vendor xdiff library from git...	r36689	} xdalgoenv_t;

		typedef struct s_xdchange {
		struct s_xdchange *next;
Jun Wu xdiff: replace {unsigned ,}long with {u,}int64_t...	r36840	int64_t i1, i2;
		int64_t chg1, chg2;
Jun Wu xdiff: vendor xdiff library from git...	r36689	int ignore;
		} xdchange_t;



Jun Wu xdiff: replace {unsigned ,}long with {u,}int64_t...	r36840	int xdl_recs_cmp(diffdata_t *dd1, int64_t off1, int64_t lim1,
		diffdata_t *dd2, int64_t off2, int64_t lim2,
		int64_t kvdf, int64_t kvdb, int need_min, xdalgoenv_t *xenv);
Jun Wu xdiff: vendor xdiff library from git...	r36689	int xdl_do_diff(mmfile_t mf1, mmfile_t mf2, xpparam_t const *xpp,
		xdfenv_t *xe);
Jun Wu xdiff: replace {unsigned ,}long with {u,}int64_t...	r36840	int xdl_change_compact(xdfile_t xdf, xdfile_t xdfo, int64_t flags);
Jun Wu xdiff: vendor xdiff library from git...	r36689	int xdl_build_script(xdfenv_t xe, xdchange_t *xscr);
		void xdl_free_script(xdchange_t *xscr);

		#endif /* #if !defined(XDIFFI_H) */