cffi: typedef shmem_{ctx|team}_t as an opaque struct type

This allows for OpenSHMEM implementations declaring ctx/team types as
either a pointer types or an integral types.

Declaring `shmem_{ctx|team}_t` as an opaque struct type has an annoying
side-effect: now ctx/team handles can no longer be compared for equality.
Therefore, add a couple auxiliary functions `eq_{ctx|team}` to compare
handles for equality. Additionally, in case we need them in the future,
add functions to convert to/from integer values.

Author: dalcinl

src/ffibuilder.py

@@ -11,8 +11,8 @@
 def build_api(
     module="api",
     shmem_h="shmem.h",
-    shmem_ctx_t='...*',
-    shmem_team_t='...*',
+    shmem_ctx_t='struct{...;}',
+    shmem_team_t='struct{...;}',
 ):
     from apicodegen import generate
     ffi = cffi.FFI()
@@ -23,6 +23,12 @@ def build_api(
         ffi.cdef(code)
     for code in generate():
         ffi.cdef(code)
+    for hdl in ('ctx', 'team'):
+        ffi.cdef(f"""
+        bool eq_{hdl}(shmem_{hdl}_t, shmem_{hdl}_t);
+        uintptr_t {hdl}2id(shmem_{hdl}_t);
+        shmem_{hdl}_t id2{hdl}(uintptr_t);
+        """)
     ffi.cdef("""
     int shmem_alltoallsmem_x(
         shmem_team_t team,

src/libshmem.c

@@ -50,6 +50,7 @@
 
 /* --- */
 
+#include "libshmem/hdltypes.h"
 #include "libshmem/fallback.h"
 #include "libshmem/initfini.h"
 #include "libshmem/memalloc.h"

src/libshmem/hdltypes.h

@@ -0,0 +1,7 @@
+#define eq_ctx(a, b) ((a) == (b))
+#define ctx2id(c) ((uintptr_t)(c))
+#define id2ctx(i) ((shmem_ctx_t)(i))
+
+#define eq_team(a, b) ((a) == (b))
+#define team2id(t) ((uintptr_t)(t))
+#define id2team(i) ((shmem_team_t)i)

src/shmem4py/shmem.py

@@ -281,15 +281,15 @@ def __new__(
     def __eq__(self, other: Any) -> bool:
         if not isinstance(other, Ctx):
             return NotImplemented
-        return self.ob_ctx == other.ob_ctx
+        return lib.eq_ctx(self.ob_ctx, other.ob_ctx)
 
     def __ne__(self, other: Any) -> bool:
         if not isinstance(other, Ctx):
             return NotImplemented
-        return self.ob_ctx != other.ob_ctx
+        return not lib.eq_ctx(self.ob_ctx, other.ob_ctx)
 
     def __bool__(self) -> bool:
-        return self.ob_ctx != lib.SHMEM_CTX_INVALID
+        return not lib.eq_ctx(self.ob_ctx, lib.SHMEM_CTX_INVALID)
 
     def __enter__(self) -> Ctx:
         return self
@@ -331,9 +331,9 @@ def destroy(self) -> None:
             return
         ctx = self.ob_ctx
         self.ob_ctx = lib.SHMEM_CTX_INVALID
-        if ctx == lib.SHMEM_CTX_DEFAULT:
+        if lib.eq_ctx(ctx, lib.SHMEM_CTX_DEFAULT):
             return
-        if ctx == lib.SHMEM_CTX_INVALID:
+        if lib.eq_ctx(ctx, lib.SHMEM_CTX_INVALID):
             return
         lib.shmem_ctx_destroy(ctx)
 
@@ -400,15 +400,15 @@ def __new__(
     def __eq__(self, other: Any) -> bool:
         if not isinstance(other, Team):
             return NotImplemented
-        return self.ob_team == other.ob_team
+        return lib.eq_team(self.ob_team, other.ob_team)
 
     def __ne__(self, other: Any) -> bool:
         if not isinstance(other, Team):
             return NotImplemented
-        return self.ob_team != other.ob_team
+        return not lib.eq_team(self.ob_team, other.ob_team)
 
     def __bool__(self) -> bool:
-        return self.ob_team != lib.SHMEM_TEAM_INVALID
+        return not lib.eq_team(self.ob_team, lib.SHMEM_TEAM_INVALID)
 
     def __enter__(self) -> Team:
         return self
@@ -426,11 +426,11 @@ def destroy(self) -> None:
             return
         team = self.ob_team
         self.ob_team = lib.SHMEM_TEAM_INVALID
-        if team == lib.SHMEM_TEAM_WORLD:
+        if lib.eq_team(team, lib.SHMEM_TEAM_WORLD):
             return
-        if team == lib.SHMEM_TEAM_SHARED:
+        if lib.eq_team(team, lib.SHMEM_TEAM_SHARED):
             return
-        if team == lib.SHMEM_TEAM_INVALID:
+        if lib.eq_team(team, lib.SHMEM_TEAM_INVALID):
             return
         lib.shmem_team_destroy(team)