thodg/libgit2/src/mwindow.h

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• Hash : b3b66c57
  Author :
  Date : 2014-06-18T17:13:12
  

  Share packs across repository instances Opening the same repository multiple times will currently open the same file multiple times, as well as map the same region of the file multiple times. This is not necessary, as the packfile data is immutable. Instead of opening and closing packfiles directly, introduce an indirection and allocate packfiles globally. This does mean locking on each packfile open, but we already use this lock for the global mwindow list so it doesn't introduce a new contention point.

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• src/mwindow.h

• /*
   * Copyright (C) the libgit2 contributors. All rights reserved.
   *
   * This file is part of libgit2, distributed under the GNU GPL v2 with
   * a Linking Exception. For full terms see the included COPYING file.
   */
  
  #ifndef INCLUDE_mwindow__
  #define INCLUDE_mwindow__
  
  #include "map.h"
  #include "vector.h"
  
  typedef struct git_mwindow {
  	struct git_mwindow *next;
  	git_map window_map;
  	git_off_t offset;
  	size_t last_used;
  	size_t inuse_cnt;
  } git_mwindow;
  
  typedef struct git_mwindow_file {
  	git_mwindow *windows;
  	int fd;
  	git_off_t size;
  } git_mwindow_file;
  
  typedef struct git_mwindow_ctl {
  	size_t mapped;
  	unsigned int open_windows;
  	unsigned int mmap_calls;
  	unsigned int peak_open_windows;
  	size_t peak_mapped;
  	size_t used_ctr;
  	git_vector windowfiles;
  } git_mwindow_ctl;
  
  int git_mwindow_contains(git_mwindow *win, git_off_t offset);
  void git_mwindow_free_all(git_mwindow_file *mwf); /* locks */
  void git_mwindow_free_all_locked(git_mwindow_file *mwf); /* run under lock */
  unsigned char *git_mwindow_open(git_mwindow_file *mwf, git_mwindow **cursor, git_off_t offset, size_t extra, unsigned int *left);
  int git_mwindow_file_register(git_mwindow_file *mwf);
  void git_mwindow_file_deregister(git_mwindow_file *mwf);
  void git_mwindow_close(git_mwindow **w_cursor);
  
  int git_mwindow_files_init(void);
  void git_mwindow_files_free(void);
  
  struct git_pack_file; /* just declaration to avoid cyclical includes */
  int git_mwindow_get_pack(struct git_pack_file **out, const char *path);
  int git_mwindow_put_pack(struct git_pack_file *pack);
  
  #endif
  

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