pass parameters string to lb SetParamters()

src/brpc/load_balancer.cpp

@@ -64,7 +64,7 @@ SharedLoadBalancer::~SharedLoadBalancer() {
 
 int SharedLoadBalancer::Init(const char* lb_protocol) {
     std::string lb_name;
-    butil::StringPairs lb_params;
+    butil::StringPiece lb_params;
     if (!ParseParameters(lb_protocol, &lb_name, &lb_params)) {
         LOG(FATAL) << "Fail to parse this load balancer protocol '" << lb_protocol << '\'';
         return -1;
@@ -101,22 +101,20 @@ void SharedLoadBalancer::Describe(std::ostream& os,
 
 bool SharedLoadBalancer::ParseParameters(const butil::StringPiece& lb_protocol,
                                          std::string* lb_name,
-                                         butil::StringPairs* lb_params) {
+                                         butil::StringPiece* lb_params) {
     lb_name->clear();
     lb_params->clear();
     if (lb_protocol.empty()) {
         return false;
     }
-    size_t pos = lb_protocol.find(':');
+    const char separator = ':';
+    size_t pos = lb_protocol.find(separator);
     if (pos == std::string::npos) {
         lb_name->append(lb_protocol.data(), lb_protocol.size());
     } else {
         lb_name->append(lb_protocol.data(), pos);
-        butil::StringPiece params_piece = lb_protocol.substr(pos + sizeof(':'));
-        std::string params_str(params_piece.data(), params_piece.size());
-        if (!butil::SplitStringIntoKeyValuePairs(params_str, '=', ' ', lb_params)) {
-            lb_params->clear();
-            return false;
+        if (pos < lb_protocol.size() - sizeof(separator)) {
+            *lb_params = lb_protocol.substr(pos + sizeof(separator));
         }
     }
 

src/brpc/load_balancer.h

@@ -106,10 +106,18 @@ public:
 
     // Config user passed parameters to lb after constrction which 
     // make lb function more flexible.
-    virtual bool SetParameters(const butil::StringPairs& params) { return true; }
+    virtual bool SetParameters(const butil::StringPiece& params) { return true; }
 
 protected:
     virtual ~LoadBalancer() { }
+    bool SplitParameters(const butil::StringPiece& params, butil::StringPairs* param_vec) {
+        std::string params_str(params.data(), params.size());
+        if (!butil::SplitStringIntoKeyValuePairs(params_str, '=', ' ', param_vec)) {
+            param_vec->clear();
+            return false;
+        }
+        return true;
+    }
 };
 
 DECLARE_bool(show_lb_in_vars);
@@ -172,7 +180,7 @@ public:
 private:
     static bool ParseParameters(const butil::StringPiece& lb_protocol,
                                 std::string* lb_name,
-                                butil::StringPairs* lb_params);
+                                butil::StringPiece* lb_params);
     static void DescribeLB(std::ostream& os, void* arg);
     void ExposeLB();
 

src/brpc/policy/consistent_hashing_load_balancer.cpp

@@ -341,8 +341,12 @@ void ConsistentHashingLoadBalancer::GetLoads(
     }
 }
 
-bool ConsistentHashingLoadBalancer::SetParameters(const butil::StringPairs& params) {
-    for (const std::pair<std::string, std::string>& param : params) {
+bool ConsistentHashingLoadBalancer::SetParameters(const butil::StringPiece& params) {
+    butil::StringPairs param_vec;
+    if (!SplitParameters(params, &param_vec)) {
+        return false;
+    }
+    for (const std::pair<std::string, std::string>& param : param_vec) {
         if (param.first == "replicas") {
             size_t replicas = 0;
             if (butil::StringToSizeT(param.second, &replicas)) {

src/brpc/policy/consistent_hashing_load_balancer.h

@@ -54,7 +54,7 @@ public:
     void Destroy();
     int SelectServer(const SelectIn &in, SelectOut *out);
     void Describe(std::ostream &os, const DescribeOptions& options);
-    virtual bool SetParameters(const butil::StringPairs& params);
+    virtual bool SetParameters(const butil::StringPiece& params);
 
 private:
     void Init(const std::string& name);