provide an api for retrieving the supported event mechanisms

svn:r788

ChangeLog

@@ -91,7 +91,7 @@ Changes in current version:
  o support for virtual HTTP hosts.
  o turn event_initialized() into a function, and add function equivalents to EVENT_SIGNAL and EVENT_FD so that people don't need to include event_struct.h
  o Build test directory correctly with CPPFLAGS set.
-
+ o Provide an API for retrieving the supported event mechanisms.
 
 Changes in 1.4.0:
  o allow \r or \n individually to separate HTTP headers instead of the standard "\r\n"; from Charles Kerr.

event.c

@@ -318,6 +318,36 @@ event_reinit(struct event_base *base)
 	return (res);
 }
 
+const char **
+event_supported_methods()
+{
+	static const char **methods;
+	const struct eventop **method;
+	const char **tmp;
+	int i = 0, k;
+
+	if (methods != NULL)
+		return (methods);
+
+	/* count all methods */
+	for (method = &eventops[0]; *method != NULL; ++method)
+		++i;
+
+	/* allocate one more than we need for the NULL pointer */
+	tmp = mm_malloc((i + 1) * sizeof(char *));
+	if (tmp == NULL)
+		return (NULL);
+
+	/* populate the array with the supported methods */
+	for (k = 0; k < i; ++k)
+		tmp[k] = eventops[k]->name;
+	tmp[i] = NULL;
+
+	methods = tmp;
+	
+	return (methods);
+}
+
 int
 event_priority_init(int npriorities)
 {

include/event2/event.h

@@ -97,6 +97,18 @@ int event_base_dispatch(struct event_base *);
  @return a string identifying the kernel event mechanism (kqueue, epoll, etc.)
  */
 const char *event_base_get_method(struct event_base *);
+
+/**
+   Gets all event notification mechanisms supported by libevent.
+
+   This functions returns the event mechanism in order preferred
+   by libevent.
+
+   @return an array with pointers to the names of support methods.
+     The end of the array is indicated by a NULL pointer.  If an
+     error is encountered NULL is returned.
+*/
+const char **event_supported_methods(void);
         
         
 /**

test/regress.c

@@ -2066,6 +2066,26 @@ test_evutil_strtoll(void)
         cleanup_test();
 }
 
+static void
+test_methods(void)
+{
+	const char **methods = event_supported_methods();
+
+	fprintf(stderr, "Testing supported methods: ");
+
+	if (methods == NULL) {
+		fprintf(stderr, "FAILED\n");
+		exit(1);
+	}
+
+	while (*methods != NULL) {
+		fprintf(stderr, "%s ", *methods);
+		++methods;
+	}
+
+	fprintf(stderr, "OK\n");
+}
+
 
 int
 main (int argc, char **argv)
@@ -2082,6 +2102,8 @@ main (int argc, char **argv)
 
 	setvbuf(stdout, NULL, _IONBF, 0);
 
+	test_methods();
+
 	/* Initalize the event library */
 	global_base = event_init();