From a60b0dc84907c323f553815dcd14e36d90ad326d Mon Sep 17 00:00:00 2001 From: Craig Ringer Date: Thu, 3 Sep 2020 13:53:29 +0800 Subject: [PATCH 6/9] Add a more succinct API for error context stack callbacks Error context stack callbacks may now be set up for a function with: void my_function(void) { PG_ERRCONTEXT_VARS(errcb); struct MyFunctionCtxArgs ctxargs; PG_ERRCONTEXT_PUSH(errcb, the_callback_fn(), ctxargs); PG_ERRCONTEXT_POP(errcb); } The macros push and pop the stack, maintain the previous error context stack pointer, etc. --- src/include/utils/elog.h | 26 +++++++++++++++++--------- 1 file changed, 17 insertions(+), 9 deletions(-) diff --git a/src/include/utils/elog.h b/src/include/utils/elog.h index 33fd1ca4a9..db713907e2 100644 --- a/src/include/utils/elog.h +++ b/src/include/utils/elog.h @@ -256,23 +256,19 @@ extern char *format_elog_string(const char *fmt,...) pg_attribute_printf(1, 2); * void * my_func(void) * { - * ErrorContextCallback errctx pgl_errcontext_check(); + * PG_ERRCONTEXT_VARS(errctx); * struct MyFuncErrctxArg ctxarg; * - * errctx.callback = my_func_errctx_callback; - * errctx.arg = &ctxarg; - * errctx.previous = error_context_stack; - * error_context_stack = &errctx; + * PG_ERRCONTEXT_PUSH(errctx, my_func_errctx_callback, &ctxarg); * * // do your normal work here but (important) do NOT return without * // popping the error context stack: * - * if (error_context_stack == &errctx) - * error_context_stack = error_context_stack->previous; + * PG_ERRCONTEXT_POP(errctx); * } * - * It's a bit verbose, but extremely valuable for adding extra diagnostic - * information to errors at runtime. + * The error context argument is optional. Your error context callback can use + * a constant message, global data, etc, instead. *------------ */ @@ -285,6 +281,18 @@ typedef struct ErrorContextCallback extern PGDLLIMPORT ErrorContextCallback *error_context_stack; +#define PG_ERRCONTEXT_VARS(varname) \ + ErrorContextCallback varname pgl_errcontext_check() + +#define PG_ERRCONTEXT_PUSH(varname, cbfunc, cbarg) \ + (varname).callback = (cbfunc); \ + (varname).arg = (cbarg); \ + (varname).previous = error_context_stack; \ + error_context_stack = &(varname) + +#define PG_ERRCONTEXT_POP(varname) \ + if (error_context_stack == &varname) \ + error_context_stack = error_context_stack->previous /*----------- * Check for error context stack escapes on cassert builds. -- 2.26.2