- Patch from Neel Goyal: Add an API call to set an event base on an

existing ub_ctx.  This basically just destroys the current worker and
  sets the event base to the current.  And fix a deadlock in
  ub_resolve_event – the cfglock is held when libworker_create is
  called.  This ends up trying to acquire the lock again in
  context_obtain_alloc in the call chain.


git-svn-id: file:///svn/unbound/trunk@2992 be551aaa-1e26-0410-a405-d3ace91eadb9

doc/Changelog

@@ -1,3 +1,11 @@
+22 Oct 2013: Wouter
+	- Patch from Neel Goyal: Add an API call to set an event base on an
+	  existing ub_ctx.  This basically just destroys the current worker and
+	  sets the event base to the current.  And fix a deadlock in
+	  ub_resolve_event – the cfglock is held when libworker_create is
+	  called.  This ends up trying to acquire the lock again in
+	  context_obtain_alloc in the call chain.
+
 26 Sep 2013: Wouter
 	- unbound-event.h is installed if configured --with-libevent.  It
 	  contains low-level library calls, that use libevent's event_base

libunbound/libunbound.c

@@ -656,15 +656,14 @@ ub_resolve_event(struct ub_ctx* ctx, const char* name, int rrtype,
 			return r;
 		}
 	}
+	lock_basic_unlock(&ctx->cfglock);
 	if(!ctx->event_worker) {
 		ctx->event_worker = libworker_create_event(ctx,
 			ctx->event_base);
 		if(!ctx->event_worker) {
-			lock_basic_unlock(&ctx->cfglock);
 			return UB_INITFAIL;
 		}
 	}
-	lock_basic_unlock(&ctx->cfglock);
 
 	/* create new ctx_query and attempt to add to the list */
 	q = context_new(ctx, name, rrtype, rrclass, (ub_callback_t)callback,
@@ -1212,3 +1211,24 @@ const char* ub_version(void)
 {
 	return PACKAGE_VERSION;
 }
+
+int 
+ub_ctx_set_event(struct ub_ctx* ctx, struct event_base* base) {
+	if (!ctx || !ctx->event_base || !base) {
+		return UB_INITFAIL;
+	}
+	if (ctx->event_base == base) {
+		/* already set */
+		return UB_NOERROR;
+	}
+	
+	lock_basic_lock(&ctx->cfglock);
+	/* destroy the current worker - safe to pass in NULL */
+	libworker_delete_event(ctx->event_worker);
+	ctx->event_worker = NULL;
+	ctx->event_base = base;	
+	ctx->created_bg = 0;
+	ctx->dothread = 1;
+	lock_basic_unlock(&ctx->cfglock);
+	return UB_NOERROR;
+}

libunbound/ubsyms.def

@@ -29,3 +29,4 @@ ub_ctx_zone_remove
 ub_ctx_data_add
 ub_ctx_data_remove
 ub_version
+ub_ctx_set_event

libunbound/unbound-event.h

@@ -63,9 +63,9 @@ extern "C" {
 struct ub_ctx;
 struct ub_result;
 struct event_base;
-struct ldns_buffer;
+struct ldns_struct_buffer;
 
-typedef void (*ub_event_callback_t)(void*, int, struct ldns_buffer*, int, char*);
+typedef void (*ub_event_callback_t)(void*, int, struct ldns_struct_buffer*, int, char*);
 
 /**
  * Create a resolving and validation context.
@@ -81,6 +81,15 @@ typedef void (*ub_event_callback_t)(void*, int, struct ldns_buffer*, int, char*)
  */
 struct ub_ctx* ub_ctx_create_event(struct event_base* base);
 
+/**
+ * Set a new event_base on a context created with ub_ctx_create_event.
+ * Any outbound queries will be canceled.
+ * @param ctx the ub_ctx to update.  Must have been created with ub_ctx_create_event
+ * @param base the new event_base to attach to the ctx
+ * @return 0 if OK, else error
+ */
+int ub_ctx_set_event(struct ub_ctx* ctx, struct event_base* base); 
+
 /**
  * Perform resolution and validation of the target name.
  * Asynchronous, after a while, the callback will be called with your