fixed an error when giving OpenMetrics statistics (#1367)

Author: Danil42Russia

common/server/stats.cpp

@@ -39,8 +39,7 @@ const char* engine_default_char_stats() {
   return engine_default_prepare_stats(tl_stats_t{}, NULL);
 }
 
-const char* engine_default_open_metrics_stat_stats() {
-  // TODO: also return the size
+std::string_view engine_default_open_metrics_stat_stats() noexcept {
   return engine_default_prepare_stats(open_metrics_stats_t{}, nullptr);
 }
 

common/server/stats.h

@@ -6,6 +6,7 @@
 
 #include <optional>
 #include <string>
+#include <string_view>
 #include <vector>
 
 #include "common/stats/provider.h"
@@ -16,7 +17,7 @@ char* get_engine_default_prepare_stats_buffer();
 std::pair<char*, int> engine_default_prepare_stats_with_tag_mask(stats_t&& stats, const char* stats_prefix, unsigned int tag_mask);
 char* engine_default_prepare_stats(stats_t&& stats, const char* stats_prefix);
 const char* engine_default_char_stats();
-const char* engine_default_open_metrics_stat_stats();
+std::string_view engine_default_open_metrics_stat_stats() noexcept;
 
 void engine_default_tl_stat_function(const std::optional<std::vector<std::string>>& sorted_filter_keys);
 extern int (*tl_stat_function)(const std::optional<std::vector<std::string>>& sorted_filter_keys);

server/php-master.cpp

@@ -1211,6 +1211,7 @@ int php_master_http_execute(struct connection *c, int op) {
     const std::string_view metrics_response = get_open_metrics_stats_http();
     write_basic_http_header(c, 200, 0, metrics_response.length(), nullptr, "text/plain; charset=UTF-8");
     write_out(&c->Out, metrics_response.data(), metrics_response.length());
+    return 0;
   }
 
   D->query_flags |= QF_ERROR;