On 9/16/21 1:06 AM, Taylor Blau wrote:
On Wed, Sep 15, 2021 at 08:36:17PM +0000, Jeff Hostetler via GitGitGadget wrote:
From: Jeff Hostetler <jeffhost@xxxxxxxxxxxxx>
Convert test helper to use `start_bg_command()` when spawning a server
daemon in the background rather than blocks of platform-specific code.
Signed-off-by: Jeff Hostetler <jeffhost@xxxxxxxxxxxxx>
---
t/helper/test-simple-ipc.c | 193 ++++++++-----------------------------
1 file changed, 40 insertions(+), 153 deletions(-)
diff --git a/t/helper/test-simple-ipc.c b/t/helper/test-simple-ipc.c
index 91345180750..59a950f3b00 100644
--- a/t/helper/test-simple-ipc.c
+++ b/t/helper/test-simple-ipc.c
@@ -9,6 +9,7 @@
#include "parse-options.h"
#include "thread-utils.h"
#include "strvec.h"
+#include "run-command.h"
#ifndef SUPPORTS_SIMPLE_IPC
int cmd__simple_ipc(int argc, const char **argv)
@@ -274,178 +275,64 @@ static int daemon__run_server(void)
return ret;
}
-#ifndef GIT_WINDOWS_NATIVE
-/*
- * This is adapted from `daemonize()`. Use `fork()` to directly create and
- * run the daemon in a child process.
- */
-static int spawn_server(pid_t *pid)
-{
- struct ipc_server_opts opts = {
- .nr_threads = cl_args.nr_threads,
- };
+static start_bg_wait_cb bg_wait_cb;
This whole patch is delightful to read, as the new implementation is so
much cleaner as a result of the earlier work in this series.
Am I correct in assuming that this is to encourage a compiler error if
bg_wait_cb does not satisfy the type of start_bg_wait_cb? If so, then I
think we are already getting that by trying to pass bg_wait_cb to
start_bg_command().
I use that trick to get the compiler to give me a compiler error at the
point of the function declaration.
For example, If I add an arg to the function that doesn't match what's
in the prototype definition, I get:
t/helper/test-simple-ipc.c:280:12: error: conflicting types for 'bg_wait_cb'
static int bg_wait_cb(const struct child_process *cp, void *cb_data, int
foo)
^
t/helper/test-simple-ipc.c:278:25: note: previous declaration is here
static start_bg_wait_cb bg_wait_cb;
^
1 error generated.
Yes, we may get an error when the function pointer is referenced in
start_bg_command() or if we're using it to initialize a vtable or
something, but those errors are further away from the actual error
(and sometimes they can be a little cryptic).
Also, it helps document that this function's signature is predefined
for a reason.
It's a quirky trick I know, but it has served me well over the years.
E.g., applying this (intentionally broken) diff on top:
--- 8< ---
diff --git a/t/helper/test-simple-ipc.c b/t/helper/test-simple-ipc.c
index 59a950f3b0..3aed787206 100644
--- a/t/helper/test-simple-ipc.c
+++ b/t/helper/test-simple-ipc.c
@@ -275,9 +275,7 @@ static int daemon__run_server(void)
return ret;
}
-static start_bg_wait_cb bg_wait_cb;
-
-static int bg_wait_cb(void *cb_data, const struct child_process *cp)
+static int bg_wait_cb(const void *cb_data, const struct child_process *cp)
{
int s = ipc_get_active_state(cl_args.path);
--- >8 ---
and then compiling still warns of a mismatched type when calling
start_bg_command().
- *pid = fork();
-
- switch (*pid) {
- case 0:
- if (setsid() == -1)
- error_errno(_("setsid failed"));
- close(0);
- close(1);
- close(2);
- sanitize_stdfds();
+static int bg_wait_cb(void *cb_data, const struct child_process *cp)
+{
+ int s = ipc_get_active_state(cl_args.path);
- return ipc_server_run(cl_args.path, &opts, test_app_cb,
- (void*)&my_app_data);
+ switch (s) {
+ case IPC_STATE__LISTENING:
+ /* child is "ready" */
+ return 0;
- case -1:
- return error_errno(_("could not spawn daemon in the background"));
+ case IPC_STATE__NOT_LISTENING:
+ case IPC_STATE__PATH_NOT_FOUND:
+ /* give child more time */
+ return 1;
default:
I'm always a little hesitant to have default cases when switch over enum
types, since it suppresses the warning when there's a new value of that
type. But we already have a similar default in client__probe_server().
Do all compilers now handle switching over an enum and detect unhandled
cases? Once upon a time that wasn't the case IIRC.
...
Ditto.
Thanks,
Taylor
