Add support for runtime arguments in injection points

The macros INJECTION_POINT() and INJECTION_POINT_CACHED() are extended
with an optional argument that can be passed down to the callback
attached when an injection point is run, giving to callbacks the
possibility to manipulate a stack state given by the caller.  The
existing callbacks in modules injection_points and test_aio have their
declarations adjusted based on that.

da7226993fd4 (core AIO infrastructure) and 93bc3d75d8e1 (test_aio) and
been relying on a set of workarounds where a static variable called
pgaio_inj_cur_handle is used as runtime argument in the injection point
callbacks used by the AIO tests, in combination with a TRY/CATCH block
to reset the argument value.  The infrastructure introduced in this
commit will be reused for the AIO tests, simplifying them.

Reviewed-by: Greg Burd <greg@burd.me>
Discussion: https://postgr.es/m/Z_y9TtnXubvYAApS@paquier.xyz

1 files changed, 8 insertions, 7 deletions

diff --git a/src/include/utils/injection_point.h b/src/include/utils/injection_point.h
index 6ba64cd1ebc..a37958e1835 100644
--- a/src/include/utils/injection_point.h
+++ b/src/include/utils/injection_point.h
@@ -16,13 +16,13 @@
  */
 #ifdef USE_INJECTION_POINTS
 #define INJECTION_POINT_LOAD(name) InjectionPointLoad(name)
-#define INJECTION_POINT(name) InjectionPointRun(name)
-#define INJECTION_POINT_CACHED(name) InjectionPointCached(name)
+#define INJECTION_POINT(name, arg) InjectionPointRun(name, arg)
+#define INJECTION_POINT_CACHED(name, arg) InjectionPointCached(name, arg)
 #define IS_INJECTION_POINT_ATTACHED(name) IsInjectionPointAttached(name)
 #else
 #define INJECTION_POINT_LOAD(name) ((void) name)
-#define INJECTION_POINT(name) ((void) name)
-#define INJECTION_POINT_CACHED(name) ((void) name)
+#define INJECTION_POINT(name, arg) ((void) name)
+#define INJECTION_POINT_CACHED(name, arg) ((void) name)
 #define IS_INJECTION_POINT_ATTACHED(name) (false)
 #endif
 
@@ -30,7 +30,8 @@
  * Typedef for callback function launched by an injection point.
  */
 typedef void (*InjectionPointCallback) (const char *name,
-										const void *private_data);
+										const void *private_data,
+										void *arg);
 
 extern Size InjectionPointShmemSize(void);
 extern void InjectionPointShmemInit(void);
@@ -41,8 +42,8 @@ extern void InjectionPointAttach(const char *name,
 								 const void *private_data,
 								 int private_data_size);
 extern void InjectionPointLoad(const char *name);
-extern void InjectionPointRun(const char *name);
-extern void InjectionPointCached(const char *name);
+extern void InjectionPointRun(const char *name, void *arg);
+extern void InjectionPointCached(const char *name, void *arg);
 extern bool IsInjectionPointAttached(const char *name);
 extern bool InjectionPointDetach(const char *name);