libdrgn: replace blocking callbacks with hard-coded functions

Now that Python support has been squashed into the main libdrgn.so,
there's no reason to go through an indirect call to release the GIL.

Signed-off-by: Omar Sandoval <osandov@osandov.com>

libdrgn/debug_info.c

@@ -5066,7 +5066,7 @@ drgn_program_load_debug_info(struct drgn_program *prog, const char **paths,
 		return NULL;
 	}
 
-	drgn_blocking_guard(prog);
+	drgn_blocking_guard();
 
 	const char *env = getenv("DRGN_MAX_DEBUG_INFO_ERRORS");
 	unsigned int max_warnings = env ? atoi(env) : 5;
@@ -5282,7 +5282,7 @@ drgn_load_module_debug_info(struct drgn_module **modules, size_t *num_modulesp)
 	for (size_t i = 0; i < num_wanted_modules; i++)
 		modules[i]->load_debug_info_generation = generation;
 
-	drgn_blocking_guard(prog);
+	drgn_blocking_guard();
 
 	const size_t orig_num_wanted_modules = num_wanted_modules;
 	drgn_handler_list_for_each_enabled(struct drgn_debug_info_finder,

libdrgn/drgn.h

@@ -1824,72 +1824,6 @@ void drgn_program_set_progress_file(struct drgn_program *prog, FILE *file);
 
 /** @} */
 
-/**
- * @defgroup Embedding Embedding
- *
- * Embedding drgn in another runtime.
- *
- * @{
- */
-
-/**
- * Callback before a blocking operation.
- *
- * @param[in] arg @c callback_arg passed to @ref
- * drgn_program_set_blocking_callback().
- * @return Opaque pointer to pass to @ref drgn_program_end_blocking_fn().
- */
-typedef void *drgn_program_begin_blocking_fn(struct drgn_program *prog,
-					     void *arg);
-
-/**
- * Callback after a blocking operation.
- *
- * @param[in] arg @c callback_arg passed to @ref
- * drgn_program_set_blocking_callback().
- * @param[in] state Return value of matching call to @ref
- * drgn_program_begin_blocking_fn().
- */
-typedef void drgn_program_end_blocking_fn(struct drgn_program *prog,
-					  void *arg, void *state);
-
-/**
- * Set callbacks around blocking operations.
- *
- * These callbacks will be called around blocking I/O operations and
- * long-running computations. They are intended for things like releasing the
- * [global interpreter
- * lock](https://docs.python.org/3/glossary.html#term-global-interpreter-lock).
- * Calls to these callbacks may be nested, but they will always be matched.
- *
- * @param[in] begin_callback Callback called before a blocking operation. Can be
- * @c NULL to unset.
- * @param[in] end_callback Callback called after a blocking operation. Can be @c
- * NULL to unset.
- * @param[in] callback_arg Argument passed to @p begin_callback and @p
- * end_callback.
- */
-void
-drgn_program_set_blocking_callback(struct drgn_program *prog,
-				   drgn_program_begin_blocking_fn *begin_callback,
-				   drgn_program_end_blocking_fn *end_callback,
-				   void *callback_arg);
-
-/**
- * Get callbacks set by @ref drgn_program_set_blocking_callback().
- *
- * @param[out] begin_callback_ret Returned @c begin_callback.
- * @param[out] end_callback_ret Returned @c end_callback.
- * @param[out] callback_arg_ret Returned @c callback_arg.
- */
-void
-drgn_program_get_blocking_callback(struct drgn_program *prog,
-				   drgn_program_begin_blocking_fn **begin_callback_ret,
-				   drgn_program_end_blocking_fn **end_callback_ret,
-				   void **callback_arg_ret);
-
-/** @} */
-
 /**
  * @defgroup Objects Objects
  *

libdrgn/dwarf_info.c

@@ -2165,7 +2165,7 @@ static struct drgn_error *index_namespace(struct drgn_namespace_dwarf_index *ns)
 		>= drgn_dwarf_index_cu_vector_size(&ns->dbinfo->dwarf.index_cus)))
 		return NULL;
 
-	drgn_blocking_guard(ns->dbinfo->prog);
+	drgn_blocking_guard();
 
 	struct drgn_error *err = drgn_dwarf_index_update(ns->dbinfo);
 	if (err)

libdrgn/program.c

@@ -2128,38 +2128,3 @@ drgn_program_element_info(struct drgn_program *prog, struct drgn_type *type,
 	ret->qualified_type = drgn_type_type(underlying_type);
 	return drgn_type_bit_size(ret->qualified_type.type, &ret->bit_size);
 }
-
-LIBDRGN_PUBLIC void
-drgn_program_set_blocking_callback(struct drgn_program *prog,
-				   drgn_program_begin_blocking_fn *begin_callback,
-				   drgn_program_end_blocking_fn *end_callback,
-				   void *callback_arg)
-{
-	prog->begin_blocking_fn = begin_callback;
-	prog->end_blocking_fn = end_callback;
-	prog->blocking_arg = callback_arg;
-}
-
-LIBDRGN_PUBLIC void
-drgn_program_get_blocking_callback(struct drgn_program *prog,
-				   drgn_program_begin_blocking_fn **begin_callback_ret,
-				   drgn_program_end_blocking_fn **end_callback_ret,
-				   void **callback_arg_ret)
-{
-	*begin_callback_ret = prog->begin_blocking_fn;
-	*end_callback_ret = prog->end_blocking_fn;
-	*callback_arg_ret = prog->blocking_arg;
-}
-
-void *drgn_program_begin_blocking(struct drgn_program *prog)
-{
-	if (!prog->begin_blocking_fn)
-		return NULL;
-	return prog->begin_blocking_fn(prog, prog->blocking_arg);
-}
-
-void drgn_program_end_blocking(struct drgn_program *prog, void *state)
-{
-	if (prog->end_blocking_fn)
-		prog->end_blocking_fn(prog, prog->blocking_arg, state);
-}

libdrgn/program.h

@@ -261,13 +261,6 @@ struct drgn_program {
 	FILE *progress_file;
 	enum drgn_log_level log_level;
 	bool default_progress_file;
-
-	/*
-	 * Blocking callbacks.
-	 */
-	drgn_program_begin_blocking_fn *begin_blocking_fn;
-	drgn_program_end_blocking_fn *end_blocking_fn;
-	void *blocking_arg;
 };
 
 /** Initialize a @ref drgn_program. */
@@ -469,49 +462,46 @@ drgn_program_register_symbol_finder_impl(struct drgn_program *prog,
 					 const struct drgn_symbol_finder_ops *ops,
 					 void *arg, size_t enable_index);
 
+#if ENABLE_PYTHON
 /**
  * Call before a blocking (I/O or long-running) operation.
  *
- * Must be paired with @ref drgn_program_end_blocking().
+ * Must be paired with @ref drgn_end_blocking().
  *
- * @return Opaque pointer to pass to @ref drgn_program_end_blocking().
+ * @return Opaque pointer to pass to @ref drgn_end_blocking().
  */
-void *drgn_program_begin_blocking(struct drgn_program *prog);
+void *drgn_begin_blocking(void);
 
 /**
  * Call after a blocking (I/O or long-running) operation.
  *
- * @param[in] state Return value of @ref drgn_program_begin_blocking().
+ * @param[in] state Return value of @ref drgn_begin_blocking().
  */
-void drgn_program_end_blocking(struct drgn_program *prog, void *state);
-
-struct drgn_blocking_guard_struct {
-	struct drgn_program *prog;
-	void *state;
-};
+void drgn_end_blocking(void *state);
+#else
+static inline void *drgn_begin_blocking(void)
+{
+	return NULL;
+}
 
-static inline struct drgn_blocking_guard_struct
-drgn_blocking_guard_init(struct drgn_program *prog)
+static inline void drgn_end_blocking(void *state)
 {
-	return (struct drgn_blocking_guard_struct){
-		prog, drgn_program_begin_blocking(prog),
-	};
 }
+#endif
 
-static inline void
-drgn_blocking_guard_cleanup(struct drgn_blocking_guard_struct *guard)
+static inline void drgn_blocking_guard_cleanup(void **statep)
 {
-	drgn_program_end_blocking(guard->prog, guard->state);
+	drgn_end_blocking(*statep);
 }
 
 /**
- * Scope guard that wraps @ref drgn_program_begin_blocking() and @ref
- * drgn_program_end_blocking().
+ * Scope guard that wraps @ref drgn_begin_blocking() and @ref
+ * drgn_end_blocking().
  */
-#define drgn_blocking_guard(prog)						\
-	struct drgn_blocking_guard_struct PP_UNIQUE(guard)			\
+#define drgn_blocking_guard()							\
+	void *PP_UNIQUE(guard)							\
 	__attribute__((__cleanup__(drgn_blocking_guard_cleanup), __unused__)) =	\
-	drgn_blocking_guard_init(prog)
+		drgn_begin_blocking()
 
 /**
  * @}

libdrgn/python/program.c

@@ -331,15 +331,15 @@ int Program_type_arg(Program *prog, PyObject *type_obj, bool can_be_none,
 	return 0;
 }
 
-static void *drgnpy_begin_blocking(struct drgn_program *prog, void *arg)
+void *drgn_begin_blocking(void)
 {
 	PyThreadState *state = PyThreadState_GetUnchecked();
 	if (state)
 		PyEval_ReleaseThread(state);
 	return state;
 }
 
-static void drgnpy_end_blocking(struct drgn_program *prog, void *arg, void *state)
+void drgn_end_blocking(void *state)
 {
 	if (state)
 		PyEval_RestoreThread(state);
@@ -357,8 +357,6 @@ static Program *Program_new_impl(const struct drgn_platform *platform)
 	prog->cache = no_cleanup_ptr(cache);
 	pyobjectp_set_init(&prog->objects);
 	drgn_program_init(&prog->prog, platform);
-	drgn_program_set_blocking_callback(&prog->prog, drgnpy_begin_blocking,
-					   drgnpy_end_blocking, NULL);
 	if (Program_init_logging(prog))
 		return NULL;
 	return_ptr(prog);