thodg/libgit2/src

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  Commit

• Hash : 2ba7020f
  Author :
  Date : 2019-06-27T09:23:59
  

  config_file: avoid re-reading files on write
  
  When we rewrite the configuration file due to any of its values
  being modified, we call `config_refresh` to update the in-memory
  representation of our config file backend. This is needlessly
  wasteful though, as `config_refresh` will always open the on-disk
  representation to reads the file contents while we already know
  the complete file contents at this point in time as we have just
  written it to disk.
  
  Implement a new function `config_refresh_from_buffer` that will
  refresh the backend's config entries from a buffer instead of
  from the config file itself. Note that this will thus _not_
  update the backend's timestamp, which will cause us to re-read
  the buffer when performing a read operation on it. But this is
  still an improvement as we now lazily re-read the contents, and
  most importantly we will avoid constantly re-reading the contents
  if we perform multiple write operations.
  
  The following strace demonstrates this if we're re-writing a key
  multiple times. It uses our config example with `config_set`
  changed to update the file 10 times with different keys:
  
  	$ strace lg2 config x.x z |& grep '^open.*config'
  	open("/tmp/repo/.git/config", O_RDONLY|O_CLOEXEC) = 3
  	open("/home/pks/.config/git/config", O_RDONLY|O_CLOEXEC) = 3
  	open("/tmp/repo/.git/config.lock", O_WRONLY|O_CREAT|O_EXCL|O_CLOEXEC, 0666) = 3
  	open("/tmp/repo/.git/config", O_RDONLY|O_CLOEXEC) = 4
  	open("/tmp/repo/.git/config", O_RDONLY|O_CLOEXEC) = 3
  	open("/tmp/repo/.git/config", O_RDONLY|O_CLOEXEC) = 3
  	open("/tmp/repo/.git/config.lock", O_WRONLY|O_CREAT|O_EXCL|O_CLOEXEC, 0666) = 3
  	open("/tmp/repo/.git/config", O_RDONLY|O_CLOEXEC) = 4
  	open("/tmp/repo/.git/config", O_RDONLY|O_CLOEXEC) = 3
  	open("/tmp/repo/.git/config", O_RDONLY|O_CLOEXEC) = 3
  	open("/tmp/repo/.git/config.lock", O_WRONLY|O_CREAT|O_EXCL|O_CLOEXEC, 0666) = 3
  	open("/tmp/repo/.git/config", O_RDONLY|O_CLOEXEC) = 4
  	open("/tmp/repo/.git/config", O_RDONLY|O_CLOEXEC) = 3
  	open("/tmp/repo/.git/config", O_RDONLY|O_CLOEXEC) = 3
  	open("/tmp/repo/.git/config.lock", O_WRONLY|O_CREAT|O_EXCL|O_CLOEXEC, 0666) = 3
  	open("/tmp/repo/.git/config", O_RDONLY|O_CLOEXEC) = 4
  	open("/tmp/repo/.git/config", O_RDONLY|O_CLOEXEC) = 3
  	open("/tmp/repo/.git/config", O_RDONLY|O_CLOEXEC) = 3
  	open("/tmp/repo/.git/config.lock", O_WRONLY|O_CREAT|O_EXCL|O_CLOEXEC, 0666) = 3
  	open("/tmp/repo/.git/config", O_RDONLY|O_CLOEXEC) = 4
  	open("/tmp/repo/.git/config", O_RDONLY|O_CLOEXEC) = 3
  	open("/tmp/repo/.git/config", O_RDONLY|O_CLOEXEC) = 3
  	open("/tmp/repo/.git/config.lock", O_WRONLY|O_CREAT|O_EXCL|O_CLOEXEC, 0666) = 3
  	open("/tmp/repo/.git/config", O_RDONLY|O_CLOEXEC) = 4
  	open("/tmp/repo/.git/config", O_RDONLY|O_CLOEXEC) = 3
  	open("/tmp/repo/.git/config", O_RDONLY|O_CLOEXEC) = 3
  	open("/tmp/repo/.git/config.lock", O_WRONLY|O_CREAT|O_EXCL|O_CLOEXEC, 0666) = 3
  	open("/tmp/repo/.git/config", O_RDONLY|O_CLOEXEC) = 4
  	open("/tmp/repo/.git/config", O_RDONLY|O_CLOEXEC) = 3
  	open("/tmp/repo/.git/config", O_RDONLY|O_CLOEXEC) = 3
  	open("/tmp/repo/.git/config.lock", O_WRONLY|O_CREAT|O_EXCL|O_CLOEXEC, 0666) = 3
  	open("/tmp/repo/.git/config", O_RDONLY|O_CLOEXEC) = 4
  	open("/tmp/repo/.git/config", O_RDONLY|O_CLOEXEC) = 3
  	open("/tmp/repo/.git/config", O_RDONLY|O_CLOEXEC) = 3
  	open("/tmp/repo/.git/config.lock", O_WRONLY|O_CREAT|O_EXCL|O_CLOEXEC, 0666) = 3
  	open("/tmp/repo/.git/config", O_RDONLY|O_CLOEXEC) = 4
  	open("/tmp/repo/.git/config", O_RDONLY|O_CLOEXEC) = 3
  	open("/tmp/repo/.git/config", O_RDONLY|O_CLOEXEC) = 3
  	open("/tmp/repo/.git/config.lock", O_WRONLY|O_CREAT|O_EXCL|O_CLOEXEC, 0666) = 3
  	open("/tmp/repo/.git/config", O_RDONLY|O_CLOEXEC) = 4
  	open("/tmp/repo/.git/config", O_RDONLY|O_CLOEXEC) = 3
  	open("/tmp/repo/.git/config", O_RDONLY|O_CLOEXEC) = 3
  
  And now with the optimization of `config_refresh_from_buffer`:
  
  	$ strace lg2 config x.x z |& grep '^open.*config'
  	open("/tmp/repo/.git/config", O_RDONLY|O_CLOEXEC) = 3
  	open("/home/pks/.config/git/config", O_RDONLY|O_CLOEXEC) = 3
  	open("/tmp/repo/.git/config.lock", O_WRONLY|O_CREAT|O_EXCL|O_CLOEXEC, 0666) = 3
  	open("/tmp/repo/.git/config", O_RDONLY|O_CLOEXEC) = 4
  	open("/tmp/repo/.git/config.lock", O_WRONLY|O_CREAT|O_EXCL|O_CLOEXEC, 0666) = 3
  	open("/tmp/repo/.git/config", O_RDONLY|O_CLOEXEC) = 4
  	open("/tmp/repo/.git/config.lock", O_WRONLY|O_CREAT|O_EXCL|O_CLOEXEC, 0666) = 3
  	open("/tmp/repo/.git/config", O_RDONLY|O_CLOEXEC) = 4
  	open("/tmp/repo/.git/config.lock", O_WRONLY|O_CREAT|O_EXCL|O_CLOEXEC, 0666) = 3
  	open("/tmp/repo/.git/config", O_RDONLY|O_CLOEXEC) = 4
  	open("/tmp/repo/.git/config.lock", O_WRONLY|O_CREAT|O_EXCL|O_CLOEXEC, 0666) = 3
  	open("/tmp/repo/.git/config", O_RDONLY|O_CLOEXEC) = 4
  	open("/tmp/repo/.git/config.lock", O_WRONLY|O_CREAT|O_EXCL|O_CLOEXEC, 0666) = 3
  	open("/tmp/repo/.git/config", O_RDONLY|O_CLOEXEC) = 4
  	open("/tmp/repo/.git/config.lock", O_WRONLY|O_CREAT|O_EXCL|O_CLOEXEC, 0666) = 3
  	open("/tmp/repo/.git/config", O_RDONLY|O_CLOEXEC) = 4
  	open("/tmp/repo/.git/config.lock", O_WRONLY|O_CREAT|O_EXCL|O_CLOEXEC, 0666) = 3
  	open("/tmp/repo/.git/config", O_RDONLY|O_CLOEXEC) = 4
  	open("/tmp/repo/.git/config.lock", O_WRONLY|O_CREAT|O_EXCL|O_CLOEXEC, 0666) = 3
  	open("/tmp/repo/.git/config", O_RDONLY|O_CLOEXEC) = 4
  	open("/tmp/repo/.git/config.lock", O_WRONLY|O_CREAT|O_EXCL|O_CLOEXEC, 0666) = 3
  	open("/tmp/repo/.git/config", O_RDONLY|O_CLOEXEC) = 4
  
  As can be seen, this is quite a lot of `open` calls less.
  

• Files

• CMakeLists.txt
• alloc.c
• alloc.h
• allocators/
• annotated_commit.c
• annotated_commit.h
• apply.c
• apply.h
• array.h
• attr.c
• attr.h
• attr_file.c
• attr_file.h
• attrcache.c
• attrcache.h
• bitvec.h
• blame.c
• blame.h
• blame_git.c
• blame_git.h
• blob.c
• blob.h
• branch.c
• branch.h
• buf_text.c
• buf_text.h
• buffer.c
• buffer.h
• cache.c
• cache.h
• cc-compat.h
• checkout.c
• checkout.h
• cherrypick.c
• clone.c
• clone.h
• commit.c
• commit.h
• commit_list.c
• commit_list.h
• common.h
• config.c
• config.h
• config_backend.h
• config_cache.c
• config_entries.c
• config_entries.h
• config_file.c
• config_mem.c
• config_parse.c
• config_parse.h
• crlf.c
• date.c
• delta.c
• delta.h
• describe.c
• diff.c
• diff.h
• diff_driver.c
• diff_driver.h
• diff_file.c
• diff_file.h
• diff_generate.c
• diff_generate.h
• diff_parse.c
• diff_parse.h
• diff_print.c
• diff_stats.c
• diff_tform.c
• diff_tform.h
• diff_xdiff.c
• diff_xdiff.h
• errors.c
• errors.h
• features.h.in
• fetch.c
• fetch.h
• fetchhead.c
• fetchhead.h
• filebuf.c
• filebuf.h
• fileops.c
• fileops.h
• filter.c
• filter.h
• global.c
• global.h
• graph.c
• hash.c
• hash.h
• hash/
• hashsig.c
• ident.c
• idxmap.c
• idxmap.h
• ignore.c
• ignore.h
• index.c
• index.h
• indexer.c
• indexer.h
• integer.h
• iterator.c
• iterator.h
• khash.h
• mailmap.c
• mailmap.h
• map.h
• merge.c
• merge.h
• merge_driver.c
• merge_driver.h
• merge_file.c
• message.c
• message.h
• mwindow.c
• mwindow.h
• net.c
• net.h
• netops.c
• netops.h
• notes.c
• notes.h
• object.c
• object.h
• object_api.c
• odb.c
• odb.h
• odb_loose.c
• odb_mempack.c
• odb_pack.c
• offmap.c
• offmap.h
• oid.c
• oid.h
• oidarray.c
• oidarray.h
• oidmap.c
• oidmap.h
• pack-objects.c
• pack-objects.h
• pack.c
• pack.h
• parse.c
• parse.h
• patch.c
• patch.h
• patch_generate.c
• patch_generate.h
• patch_parse.c
• patch_parse.h
• path.c
• path.h
• pathspec.c
• pathspec.h
• pool.c
• pool.h
• posix.c
• posix.h
• posix_regex.h
• pqueue.c
• pqueue.h
• proxy.c
• proxy.h
• push.c
• push.h
• reader.c
• reader.h
• rebase.c
• refdb.c
• refdb.h
• refdb_fs.c
• refdb_fs.h
• reflog.c
• reflog.h
• refs.c
• refs.h
• refspec.c
• refspec.h
• remote.c
• remote.h
• repo_template.h
• repository.c
• repository.h
• reset.c
• revert.c
• revparse.c
• revwalk.c
• revwalk.h
• settings.c
• sha1_lookup.c
• sha1_lookup.h
• signature.c
• signature.h
• sortedcache.c
• sortedcache.h
• stash.c
• status.c
• status.h
• stream.h
• streams/
• strmap.c
• strmap.h
• strnlen.h
• submodule.c
• submodule.h
• sysdir.c
• sysdir.h
• tag.c
• tag.h
• thread-utils.c
• thread-utils.h
• trace.c
• trace.h
• trailer.c
• transaction.c
• transaction.h
• transport.c
• transports/
• tree-cache.c
• tree-cache.h
• tree.c
• tree.h
• tsort.c
• unix/
• userdiff.h
• util.c
• util.h
• varint.c
• varint.h
• vector.c
• vector.h
• wildmatch.c
• wildmatch.h
• win32/
• worktree.c
• worktree.h
• xdiff/
• zstream.c
• zstream.h

• Properties

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  Git SSH	git@git.kmx.io:thodg/libgit2.git
  Public access ?	public
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