[RFC PATCH v3 3/9] libcamera: process: Use `pid_` member to decide if running

[Kieran Bingham]

Quoting Barnabás Pőcze (2025-03-25 18:08:15)
> Instead of using a separate member variable, use `pid_ > 0` to determine
> if the process is still running. Previously the value of `pid_` was not
> reset to -1 when the process terminated, but since it is only meaningful
> while the process is running, reset it to -1 in `Process::died()`.
> 
> Neither `pid_` nor `running_` are exposed, so this change has no effect
> on the public interface or observable behaviour.
> 
> Signed-off-by: Barnabás Pőcze <barnabas.pocze at ideasonboard.com>

Reviewed-by: Kieran Bingham <kieran.bingham at ideasonboard.com>

> ---
>  include/libcamera/internal/process.h | 1 -
>  src/libcamera/process.cpp            | 8 +++-----
>  2 files changed, 3 insertions(+), 6 deletions(-)
> 
> diff --git a/include/libcamera/internal/process.h b/include/libcamera/internal/process.h
> index 58e3e41ce..030a1e66e 100644
> --- a/include/libcamera/internal/process.h
> +++ b/include/libcamera/internal/process.h
> @@ -49,7 +49,6 @@ private:
>         void died(int wstatus);
>  
>         pid_t pid_;
> -       bool running_;
>         enum ExitStatus exitStatus_;
>         int exitCode_;
>  
> diff --git a/src/libcamera/process.cpp b/src/libcamera/process.cpp
> index 567b878d4..aa9e8f519 100644
> --- a/src/libcamera/process.cpp
> +++ b/src/libcamera/process.cpp
> @@ -208,7 +208,7 @@ const struct sigaction &ProcessManager::oldsa() const
>   */
>  
>  Process::Process()
> -       : pid_(-1), running_(false), exitStatus_(NotExited), exitCode_(0)
> +       : pid_(-1), exitStatus_(NotExited), exitCode_(0)
>  {
>  }
>  
> @@ -240,7 +240,7 @@ int Process::start(const std::string &path,
>  {
>         int ret;
>  
> -       if (running_)
> +       if (pid_ > 0)
>                 return 0;
>  
>         int childPid = fork();
> @@ -252,8 +252,6 @@ int Process::start(const std::string &path,
>                 pid_ = childPid;
>                 ProcessManager::instance()->registerProcess(this);
>  
> -               running_ = true;
> -
>                 return 0;
>         } else {
>                 if (isolate())
> @@ -327,7 +325,7 @@ int Process::isolate()
>   */
>  void Process::died(int wstatus)
>  {
> -       running_ = false;
> +       pid_ = -1;
>         exitStatus_ = WIFEXITED(wstatus) ? NormalExit : SignalExit;
>         exitCode_ = exitStatus_ == NormalExit ? WEXITSTATUS(wstatus) : -1;
>  
> -- 
> 2.49.0
>