[PATCH 1/2] run-command: provide in_async query function
- From
Jeff King <peff@peff.net>
- Date
- Sep 1, 2015, 20:22 UTC
- Message-ID
- <20150901202243.GA6931@sigill.intra.peff.net>
- In-Reply-To
- <20150901202215.GA17370@sigill.intra.peff.net>
It's not easy for arbitrary code to find out whether it is running in an async process or not. A top-level function which is fed to start_async() can know (you just pass down an argument saying "you are async"). But that function may call other global functions, and we would not want to have to pass the information all the way through the call stack.
Nor can we simply set a global variable, as those may be shared between async threads and the main thread (if the platform supports pthreads). We need pthread tricks _or_ a global variable, depending on how start_async is implemented.
The callers don't have enough information to do this right, so let's provide a simple query function that does. Fortunately we can reuse the existing infrastructure to make the pthread case simple (and even simplify die_async() by using our new function).
Signed-off-by: Jeff King <peff@peff.net> --- run-command.c | 16 +++++++++++++++- run-command.h | 1 + 2 files changed, 16 insertions(+), 1 deletion(-)
diff --git a/run-command.c b/run-command.c index 3277cf7..c8029f2 100644 --- a/run-command.c +++ b/run-command.c @@ -595,7 +595,7 @@ static NORETURN void die_async(const char *err, va_list params) { vreportf("fatal: ", err, params); - if (!pthread_equal(main_thread, pthread_self())) { + if (in_async()) { struct async *async = pthread_getspecific(async_key); if (async->proc_in >= 0) close(async->proc_in); @@ -614,6 +614,13 @@ static int async_die_is_recursing(void) return ret != NULL; } +int in_async(void) +{ + if (!main_thread_set) + return 0; /* no asyncs started yet */ + return !pthread_equal(main_thread, pthread_self()); +} + #else static struct { @@ -653,6 +660,12 @@ int git_atexit(void (*handler)(void)) } #define atexit git_atexit +static int process_is_async; +int in_async(void) +{ + return process_is_async; +} + #endif int start_async(struct async *async) @@ -712,6 +725,7 @@ int start_async(struct async *async) if (need_out) close(fdout[0]); git_atexit_clear(); + process_is_async = 1; exit(!!async->proc(proc_in, proc_out, async->data)); } diff --git a/run-command.h b/run-command.h index 5b4425a..629fab7 100644 --- a/run-command.h +++ b/run-command.h @@ -118,5 +118,6 @@ struct async { int start_async(struct async *async); int finish_async(struct async *async); +int in_async(void); #endif
-- 2.5.1.739.g7891f6b