Commits on Jul 22, 2021

1. tr2: make process info collection platform-generic …

   To pave the way for non-Windows platforms to define
   trace2_collect_process_info(), reorganize the stub-or-definition schema
   to something which doesn't directly reference Windows.
   
   Platforms which want to collect parent process information in the
   future should:
   
    1. Add an implementation to compat/ (e.g. compat/somearch/procinfo.c)
    2. Add that object to COMPAT_OBJS to config.mak.uname
       (e.g. COMPAT_OBJS += compat/somearch/procinfo.o)
    3. Define HAVE_PLATFORM_PROCINFO in config.mak.uname
   
   In the Windows case, this definition lives in
   compat/win32/trace2_win32_process_info.c, which is already conditionally
   added to COMPAT_OBJS; so let's add HAVE_PLATFORM_PROCINFO to hint to the
   build that compat/stub/procinfo.c should not be used.
   
   Signed-off-by: Emily Shaffer <emilyshaffer@google.com>
   Helped-by: Jonathan Nieder <jrnieder@gmail.com>
   Signed-off-by: Junio C Hamano <gitster@pobox.com>

   

   nasamuffin authored and gitster committed Jul 22, 2021
   Copy the full SHA

   b7e6a41 View commit details

   Browse the repository at this point in the history

2. tr2: log parent process name …

   It can be useful to tell who invoked Git - was it invoked manually by a
   user via CLI or script? By an IDE?  In some cases - like 'repo' tool -
   we can influence the source code and set the GIT_TRACE2_PARENT_SID
   environment variable from the caller process. In 'repo''s case, that
   parent SID is manipulated to include the string "repo", which means we
   can positively identify when Git was invoked by 'repo' tool. However,
   identifying parents that way requires both that we know which tools
   invoke Git and that we have the ability to modify the source code of
   those tools. It cannot scale to keep up with the various IDEs and
   wrappers which use Git, most of which we don't know about. Learning
   which tools and wrappers invoke Git, and how, would give us insight to
   decide where to improve Git's usability and performance.
   
   Unfortunately, there's no cross-platform reliable way to gather the name
   of the parent process. If procfs is present, we can use that; otherwise
   we will need to discover the name another way. However, the process ID
   should be sufficient to look up the process name on most platforms, so
   that code may be shareable.
   
   Git for Windows gathers similar information and logs it as a "data_json"
   event. However, since "data_json" has a variable format, it is difficult
   to parse effectively in some languages; instead, let's pursue a
   dedicated "cmd_ancestry" event to record information about the ancestry
   of the current process and a consistent, parseable way.
   
   Git for Windows also gathers information about more than one generation
   of parent. In Linux further ancestry info can be gathered with procfs,
   but it's unwieldy to do so. In the interest of later moving Git for
   Windows ancestry logging to the 'cmd_ancestry' event, and in the
   interest of later adding more ancestry to the Linux implementation - or
   of adding this functionality to other platforms which have an easier
   time walking the process tree - let's make 'cmd_ancestry' accept an
   array of parentage.
   
   Signed-off-by: Emily Shaffer <emilyshaffer@google.com>
   Signed-off-by: Junio C Hamano <gitster@pobox.com>

   

   nasamuffin authored and gitster committed Jul 22, 2021
   Copy the full SHA

   2f732bf View commit details

   Browse the repository at this point in the history