src: Minor optimization for appending single character

src/HttpServer.cc

@@ -1228,7 +1228,7 @@ void prepare_response(Stream *stream, Http2Handler *hd,
       close(file);
 
       if (query_pos == std::string::npos) {
-        reqpath += "/";
+        reqpath += '/';
       } else {
         reqpath.insert(query_pos, "/");
       }

src/asio_client_session_impl.cc

@@ -420,10 +420,10 @@ const request *session_impl::submit(boost::system::error_code &ec,
 
   if (util::ipv6_numeric_addr(uref.host.c_str())) {
     uref.host = "[" + uref.host;
-    uref.host += "]";
+    uref.host += ']';
   }
   if (u.field_set & (1 << UF_PORT)) {
-    uref.host += ":";
+    uref.host += ':';
     uref.host += util::utos(u.port);
   }
 
@@ -435,7 +435,7 @@ const request *session_impl::submit(boost::system::error_code &ec,
 
   auto path = uref.raw_path;
   if (u.field_set & (1 << UF_QUERY)) {
-    path += "?";
+    path += '?';
     path += uref.raw_query;
   }
 

src/asio_server_serve_mux.cc

@@ -83,7 +83,7 @@ request_cb serve_mux::handler(request_impl &req) const {
       auto new_uri = util::percent_encode_path(clean_path);
       auto &uref = req.uri();
       if (!uref.raw_query.empty()) {
-        new_uri += "?";
+        new_uri += '?';
         new_uri += uref.raw_query;
       }
 

src/h2load.cc

@@ -1177,7 +1177,7 @@ std::string get_reqline(const char *uri, const http_parser_url &u) {
   }
 
   if (util::has_uri_field(u, UF_QUERY)) {
-    reqline += "?";
+    reqline += '?';
     reqline += util::get_uri_field(uri, u, UF_QUERY);
   }
 
@@ -1954,7 +1954,7 @@ int main(int argc, char **argv) {
   for (auto &req : reqlines) {
     // For HTTP/1.1
     auto h1req = (*method_it).value;
-    h1req += " ";
+    h1req += ' ';
     h1req += req;
     h1req += " HTTP/1.1\r\n";
     for (auto &nv : shared_nva) {

src/http2.cc

@@ -471,12 +471,12 @@ std::string rewrite_location_uri(const std::string &uri,
   }
   if (u.field_set & (1 << UF_QUERY)) {
     field = &u.field_data[UF_QUERY];
-    res += "?";
+    res += '?';
     res.append(&uri[field->off], field->len);
   }
   if (u.field_set & (1 << UF_FRAGMENT)) {
     field = &u.field_data[UF_FRAGMENT];
-    res += "#";
+    res += '#';
     res.append(&uri[field->off], field->len);
   }
   return res;
@@ -1185,12 +1185,12 @@ std::string path_join(const char *base_path, size_t base_pathlen,
     }
     if (rel_querylen == 0) {
       if (base_querylen) {
-        res += "?";
+        res += '?';
         res.append(base_query, base_querylen);
       }
       return res;
     }
-    res += "?";
+    res += '?';
     res.append(rel_query, rel_querylen);
     return res;
   }
@@ -1242,7 +1242,7 @@ std::string path_join(const char *base_path, size_t base_pathlen,
       ;
   }
   if (rel_querylen) {
-    res += "?";
+    res += '?';
     res.append(rel_query, rel_querylen);
   }
   return res;
@@ -1500,7 +1500,7 @@ int construct_push_component(std::string &scheme, std::string &authority,
     if (u.field_set & (1 << UF_HOST)) {
       http2::copy_url_component(authority, &u, UF_HOST, uri);
       if (u.field_set & (1 << UF_PORT)) {
-        authority += ":";
+        authority += ':';
         authority += util::utos(u.port);
       }
     }

src/nghttp.cc

@@ -168,7 +168,7 @@ std::string Request::make_reqpath() const {
                          ? util::get_uri_field(uri.c_str(), u, UF_PATH)
                          : "/";
   if (util::has_uri_field(u, UF_QUERY)) {
-    path += "?";
+    path += '?';
     path.append(uri.c_str() + u.field_data[UF_QUERY].off,
                 u.field_data[UF_QUERY].len);
   }
@@ -828,7 +828,7 @@ int HttpClient::on_upgrade_connect() {
       reqvec[0]->method = "GET";
     } else {
       req = (*meth).value;
-      req += " ";
+      req += ' ';
       reqvec[0]->method = (*meth).value;
     }
     req += reqvec[0]->make_reqpath();

src/shrpx_config.cc

@@ -596,7 +596,7 @@ void parse_mapping(const DownstreamAddr &addr, const char *src) {
       // This effectively makes empty pattern to "/".
       pattern.assign(raw_pattern.first, raw_pattern.second);
       util::inp_strlower(pattern);
-      pattern += "/";
+      pattern += '/';
     } else {
       pattern.assign(raw_pattern.first, slash);
       util::inp_strlower(pattern);

src/shrpx_http.cc

@@ -55,7 +55,7 @@ std::string create_via_header_value(int major, int minor) {
   std::string hdrs;
   hdrs += static_cast<char>(major + '0');
   if (major < 2) {
-    hdrs += ".";
+    hdrs += '.';
     hdrs += static_cast<char>(minor + '0');
   }
   hdrs += " nghttpx";

src/shrpx_http2_session.cc

@@ -520,7 +520,7 @@ int Http2Session::downstream_connect_proxy() {
   std::string req = "CONNECT ";
   req += downstream_addr.hostport.get();
   if (downstream_addr.port == 80 || downstream_addr.port == 443) {
-    req += ":";
+    req += ':';
     req += util::utos(downstream_addr.port);
   }
   req += " HTTP/1.1\r\nHost: ";

src/shrpx_log.cc

@@ -297,7 +297,7 @@ void upstream_accesslog(const std::vector<LogFragment> &lfv,
       if (frac.size() < 3) {
         frac = std::string(3 - frac.size(), '0') + frac;
       }
-      sec += ".";
+      sec += '.';
       sec += frac;
 
       std::tie(p, avail) = copy(sec, avail, p);
@@ -415,12 +415,12 @@ void log_chld(pid_t pid, int rstatus, const char *msg) {
     auto s = strsignal(sig);
     if (s) {
       signalstr += s;
-      signalstr += "(";
+      signalstr += '(';
     } else {
       signalstr += "UNKNOWN(";
     }
     signalstr += util::utos(sig);
-    signalstr += ")";
+    signalstr += ')';
   }
 
   LOG(NOTICE) << msg << ": [" << pid << "] exited "

src/util.cc

@@ -89,7 +89,7 @@ std::string percentEncode(const unsigned char *target, size_t len) {
     if (inRFC3986UnreservedChars(c)) {
       dest += c;
     } else {
-      dest += "%";
+      dest += '%';
       dest += UPPER_XDIGITS[c >> 4];
       dest += UPPER_XDIGITS[(c & 0x0f)];
     }
@@ -110,7 +110,7 @@ std::string percent_encode_path(const std::string &s) {
       continue;
     }
 
-    dest += "%";
+    dest += '%';
     dest += UPPER_XDIGITS[(c >> 4) & 0x0f];
     dest += UPPER_XDIGITS[(c & 0x0f)];
   }
@@ -141,7 +141,7 @@ std::string percent_encode_token(const std::string &target) {
     if (c != '%' && in_token(c)) {
       dest += c;
     } else {
-      dest += "%";
+      dest += '%';
       dest += UPPER_XDIGITS[c >> 4];
       dest += UPPER_XDIGITS[(c & 0x0f)];
     }
@@ -712,7 +712,7 @@ std::string ascii_dump(const uint8_t *data, size_t len) {
     if (c >= 0x20 && c < 0x7f) {
       res += c;
     } else {
-      res += ".";
+      res += '.';
     }
   }
 
@@ -1103,17 +1103,17 @@ std::string make_hostport(const char *host, uint16_t port) {
   std::string hostport;
 
   if (ipv6) {
-    hostport += "[";
+    hostport += '[';
   }
 
   hostport += host;
 
   if (ipv6) {
-    hostport += "]";
+    hostport += ']';
   }
 
   if (port != 80 && port != 443) {
-    hostport += ":";
+    hostport += ':';
     hostport += utos(port);
   }