Re: [PATCH v7 14/17] run-command: add stdin callback for parallelization

> If a user of the run_processes_parallel() API wants to pipe a large
> amount of information to stdin of each parallel command, that
> information could exceed the buffer of the pipe allocated for that
> process's stdin.  Generally this is solved by repeatedly writing to
> child_process.in between calls to start_command() and finish_command();
> run_processes_parallel() did not provide users an opportunity to access
> child_process at that time.

> diff --git a/run-command.h b/run-command.h
> index 6472b38bde..e058c0e2c8 100644
> --- a/run-command.h
> +++ b/run-command.h
> @@ -436,6 +436,20 @@ typedef int (*start_failure_fn)(struct strbuf *out,
>  				void *pp_cb,
>  				void *pp_task_cb);
>  
> +/**
> + * This callback is called repeatedly on every child process who requests
> + * start_command() to create a pipe by setting child_process.in < 0.
> + *
> + * pp_cb is the callback cookie as passed into run_processes_parallel, and
> + * pp_task_cb is the callback cookie as passed into get_next_task_fn.
> + * The contents of 'send' will be read into the pipe and passed to the pipe.
> + *
> + * Return nonzero to close the pipe.
> + */
> +typedef int (*feed_pipe_fn)(struct strbuf *pipe,
> +			    void *pp_cb,
> +			    void *pp_task_cb);
> +