Check 'breaker_list' before locking. (sogou#1767)

* Check breaker_list before locking.

* Remove 'pre_select'.

Author: Barenboim

src/nameservice/WFDnsResolver.h

@@ -61,7 +61,6 @@ class WFResolverTask : public WFRouterTask
 protected:
 	virtual void dispatch();
 	virtual SubTask *done();
-	void set_has_next() { has_next_ = true; }
 
 private:
 	void thread_dns_callback(void *thrd_dns_task);

src/nameservice/WFServiceGovernance.cc

@@ -144,23 +144,6 @@ void WFSGResolverTask::dispatch()
 		return;
 	}
 
-	if (sg_->pre_select_)
-	{
-		WFConditional *cond = sg_->pre_select_(this);
-		if (cond)
-		{
-			series_of(this)->push_front(cond);
-			this->set_has_next();
-			this->subtask_done();
-			return;
-		}
-		else if (this->state != WFT_STATE_UNDEFINED)
-		{
-			this->subtask_done();
-			return;
-		}
-	}
-
 	if (sg_->select(ns_params_.uri, tracing, &addr))
 	{
 		auto *tracing_data = (WFServiceGovernance::TracingData *)tracing->data;
@@ -324,10 +307,12 @@ void WFServiceGovernance::check_breaker_locked(int64_t cur_time)
 
 void WFServiceGovernance::check_breaker()
 {
-	pthread_mutex_lock(&this->breaker_lock);
 	if (!list_empty(&this->breaker_list))
+	{
+		pthread_mutex_lock(&this->breaker_lock);
 		this->check_breaker_locked(GET_CURRENT_SECOND);
-	pthread_mutex_unlock(&this->breaker_lock);
+		pthread_mutex_unlock(&this->breaker_lock);
+	}
 }
 
 void WFServiceGovernance::try_clear_breaker()

src/nameservice/WFServiceGovernance.h

@@ -25,7 +25,6 @@
 #include <unordered_map>
 #include <vector>
 #include <atomic>
-#include <functional>
 #include "URIParser.h"
 #include "EndpointParams.h"
 #include "WFNameService.h"
@@ -123,14 +122,6 @@ class WFServiceGovernance : public WFNSPolicy
 
 	static bool in_select_history(WFNSTracing *tracing, EndpointAddress *addr);
 
-public:
-	using pre_select_t = std::function<WFConditional *(WFRouterTask *)>;
-
-	void set_pre_select(pre_select_t pre_select)
-	{
-		pre_select_ = std::move(pre_select);
-	}
-
 private:
 	virtual bool select(const ParsedURI& uri, WFNSTracing *tracing,
 						EndpointAddress **addr);
@@ -156,7 +147,6 @@ class WFServiceGovernance : public WFNSPolicy
 	struct list_head breaker_list;
 	pthread_mutex_t breaker_lock;
 	unsigned int mttr_seconds;
-	pre_select_t pre_select_;
 
 protected:
 	virtual EndpointAddress *first_strategy(const ParsedURI& uri,