[PATCH 5/6] Reimplement async procedures using pthreads
On Windows, async procedures have always been run in threads, and the implementation used Windows specific APIs. Rewrite the code to use pthreads.
A new configuration option is introduced so that the threaded implementation can also be used on POSIX systems. Since this option is intended only as playground on POSIX, but is mandatory on Windows, the option is not documented.
One detail is that on POSIX it is necessary to set FD_CLOEXEC on the pipe handles. On Windows, this is not needed because pipe handles are not inherited to child processes, and the new calls to set_cloexec() are effectively no-ops.
Signed-off-by: Johannes Sixt <j6t@kdbg.org>
---
Makefile | 5 +++++
run-command.c | 41 +++++++++++++++++++++++------------------
run-command.h | 8 ++++++--
3 files changed, 34 insertions(+), 20 deletions(-)
Show changes to 3 files +34 −20
Makefile, run-command.c, run-command.h
diff --git a/Makefile b/Makefile
index afedb54..c5f0f9b 100644
--- a/Makefile
+++ b/Makefile
@@ -949,6 +949,7 @@ ifeq ($(uname_S),Windows)
NO_CURL = YesPlease
NO_PYTHON = YesPlease
BLK_SHA1 = YesPlease
+ ASYNC_AS_THREAD = YesPlease
CC = compat/vcbuild/scripts/clink.pl
AR = compat/vcbuild/scripts/lib.pl
@@ -1000,6 +1001,7 @@ ifneq (,$(findstring MINGW,$(uname_S)))
NO_REGEX = YesPlease
NO_PYTHON = YesPlease
BLK_SHA1 = YesPlease
+ ASYNC_AS_THREAD = YesPlease
COMPAT_CFLAGS += -D__USE_MINGW_ACCESS -DNOGDI -Icompat -Icompat/fnmatch -Icompat/win32
COMPAT_CFLAGS += -DSTRIP_EXTENSION=\".exe\"
COMPAT_OBJS += compat/mingw.o compat/fnmatch/fnmatch.o compat/winansi.o \
@@ -1301,6 +1303,9 @@ ifdef NO_PTHREADS
else
EXTLIBS += $(PTHREAD_LIBS)
LIB_OBJS += thread-utils.o
+ifdef ASYNC_AS_THREAD
+ BASIC_CFLAGS += -DASYNC_AS_THREAD
+endif
endif
ifdef DIR_HAS_BSD_GROUP_SEMANTICS
diff --git a/run-command.c b/run-command.c
index 0cd7f02..77aefff 100644
--- a/run-command.c
+++ b/run-command.c
@@ -82,6 +82,7 @@ static NORETURN void die_child(const char *err, va_list params)
write(child_err, "\n", 1);
exit(128);
}
+#endif
static inline void set_cloexec(int fd)
{
@@ -89,7 +90,6 @@ static inline void set_cloexec(int fd)
if (flags >= 0)
fcntl(fd, F_SETFD, flags | FD_CLOEXEC);
}
-#endif
static int wait_or_whine(pid_t pid, const char *argv0, int silent_exec_failure)
{
@@ -447,11 +447,12 @@ int run_command_v_opt_cd_env(const char **argv, int opt, const char *dir, const
return run_command(&cmd);
}
-#ifdef WIN32
-static unsigned __stdcall run_thread(void *data)
+#ifdef ASYNC_AS_THREAD
+static void *run_thread(void *data)
{
struct async *async = data;
- return async->proc(async->proc_in, async->proc_out, async->data);
+ intptr_t ret = async->proc(async->proc_in, async->proc_out, async->data);
+ return (void *)ret;
}
#endif
@@ -497,7 +498,7 @@ int start_async(struct async *async)
else
proc_out = -1;
-#ifndef WIN32
+#ifndef ASYNC_AS_THREAD
/* Flush stdio before fork() to avoid cloning buffers */
fflush(NULL);
@@ -524,12 +525,18 @@ int start_async(struct async *async)
else if (async->out)
close(async->out);
#else
+ if (proc_in >= 0)
+ set_cloexec(proc_in);
+ if (proc_out >= 0)
+ set_cloexec(proc_out);
async->proc_in = proc_in;
async->proc_out = proc_out;
- async->tid = (HANDLE) _beginthreadex(NULL, 0, run_thread, async, 0, NULL);
- if (!async->tid) {
- error("cannot create thread: %s", strerror(errno));
- goto error;
+ {
+ int err = pthread_create(&async->tid, NULL, run_thread, async);
+ if (err) {
+ error("cannot create thread: %s", strerror(err));
+ goto error;
+ }
}
#endif
return 0;
@@ -549,17 +556,15 @@ error:
int finish_async(struct async *async)
{
-#ifndef WIN32
- int ret = wait_or_whine(async->pid, "child process", 0);
+#ifndef ASYNC_AS_THREAD
+ return wait_or_whine(async->pid, "child process", 0);
#else
- DWORD ret = 0;
- if (WaitForSingleObject(async->tid, INFINITE) != WAIT_OBJECT_0)
- ret = error("waiting for thread failed: %lu", GetLastError());
- else if (!GetExitCodeThread(async->tid, &ret))
- ret = error("cannot get thread exit code: %lu", GetLastError());
- CloseHandle(async->tid);
+ void *ret = (void *)(intptr_t)(-1);
+
+ if (pthread_join(async->tid, &ret))
+ error("pthread_join failed");
+ return (int)(intptr_t)ret;
#endif
- return ret;
}
int run_hook(const char *index_file, const char *name, ...)
diff --git a/run-command.h b/run-command.h
index 94619f5..40db39c 100644
--- a/run-command.h
+++ b/run-command.h
@@ -1,6 +1,10 @@
#ifndef RUN_COMMAND_H
#define RUN_COMMAND_H
+#ifdef ASYNC_AS_THREAD
+#include <pthread.h>
+#endif
+
struct child_process {
const char **argv;
pid_t pid;
@@ -74,10 +78,10 @@ struct async {
void *data;
int in; /* caller writes here and closes it */
int out; /* caller reads from here and closes it */
-#ifndef WIN32
+#ifndef ASYNC_AS_THREAD
pid_t pid;
#else
- HANDLE tid;
+ pthread_t tid;
int proc_in;
int proc_out;
#endif
--
1.7.0.rc2.65.g7b13a
Johannes Sixt