On May 18, 2021 4:24 AM, Jeff King wrote: >On Mon, May 17, 2021 at 01:46:46PM -0400, Randall S. Becker wrote: > >> On Wed, 17 Feb 2021 21:48:36, Jeff Hostetler wrote: >> >> >Here is V4 of my "Simple IPC" series. It addresses Gábor's comment >> >WRT shutting down the server to make unit tests more predictable on CI servers. >> >(https://lore.kernel.org/git/20210213093052.GJ1015009@xxxxxxxxxx) >> >> I missed this at the time, but it appears that ipc-unix-socket.c >> forces a dependency on pthreads for Git under Unix-like platforms. >> This is probably not a correct assumption (or likely intended), but >> causes git to no longer build on NonStop x86 and ia64 as of >> 2.32.0-rc0. I am not suggesting undoing this, but amending to make the >> change more sensitive to a lack of pthread support. >> pthread_sigmask() showed up as an undefined external: > >Hrm. Usually we do not assume that threads are available. For "async" >stuff via run-command, we allow it to be implemented via fork(), and insist that the async process talk back to us only over a pipe >descriptor (so it works whether it's a thread or a separate process). >In cases where we use worker threads for performance (like index-pack or pack-objects), we just run a single "thread" instead, waiting for >it to complete. > >In the simple-ipc API, there's an explicit "async" interface. But it's not clear to me how rich it expects the communication with the caller to >be (i.e., whether we could get away with the fork() trick here). Or if it would be OK for the threading to remain an implementation detail, >with one "worker" upon whom we wait for completion. > >> **** ERROR **** [1210]: >> libgit.a(ipc-unix-socket.o): In function `thread_block_sigpipe': >> ipc-unix-socket.o(.text+0xb87): unresolved reference to pthread_sigmask. >> >> On NonStop, pthread_sigmask is defined in -lput or -lspt, which are >> not used in our build – and would cause a bunch of other issues if referenced. The build does define NO_PTHREADS. > >So yeah, you hit that problem because you only have a sort-of-pthreads-ish case. But it seems like a system which truly has no pthread >support at all and defines NO_PTHREADS to tell us so will have much more of its compilation broken (because it's also missing obvious bits >like pthread_create()). > >We already make simple-ipc compilation conditional on NO_UNIX_SOCKETS. I think we could probably just do the same for >NO_PTHREADS? > >Something like: > >diff --git a/Makefile b/Makefile >index 3a2d3c80a8..bd7fe0fc24 100644 >--- a/Makefile >+++ b/Makefile >@@ -1687,14 +1687,20 @@ ifdef NO_UNIX_SOCKETS else > LIB_OBJS += unix-socket.o > LIB_OBJS += unix-stream-server.o >+endif >+ >+# All simple-ipc requires threads, and then individual # mechanisms >+have their own requirements. >+ifndef NO_PTHREADS >+ BASIC_CFLAGS += -DSUPPORTS_SIMPLE_IPC > LIB_OBJS += compat/simple-ipc/ipc-shared.o >+ifndef NO_UNIX_SOCKETS > LIB_OBJS += compat/simple-ipc/ipc-unix-socket.o > endif >- > ifdef USE_WIN32_IPC >- LIB_OBJS += compat/simple-ipc/ipc-shared.o > LIB_OBJS += compat/simple-ipc/ipc-win32.o endif >+endif > > ifdef NO_ICONV > BASIC_CFLAGS += -DNO_ICONV >diff --git a/simple-ipc.h b/simple-ipc.h index dc3606e30b..0f58be7945 100644 >--- a/simple-ipc.h >+++ b/simple-ipc.h >@@ -4,11 +4,6 @@ > /* > * See Documentation/technical/api-simple-ipc.txt > */ >- >-#if defined(GIT_WINDOWS_NATIVE) || !defined(NO_UNIX_SOCKETS) -#define SUPPORTS_SIMPLE_IPC -#endif >- > #ifdef SUPPORTS_SIMPLE_IPC > #include "pkt-line.h" I'm not sure this is going to work. The platform *does* support UNIX sockets (and not disabled) and pthreads, but we have disabled pthreads in our build. So in the above, ipc-unix-socket.o will be included at the ifndef NO_UNIX_SOCKETS. If NO_PTHREADS, not being pedantic, there should be no pthread references, regardless of other considerations. Although, at some point, I hope to resolve why pthreads (PUT) is having issues in git on the platform but not at this point.
