Minor performance improvements setting up intervention's log

- Initialize `log` temporary value on construction instead of doing
  default initialization and then calling `append`.
- Leverage `std::string_view` to replace `const std::string&` parameters
  in `utils::string::replaceAll` to avoid creating a `std::string`
  object (and associated allocation and copy) for the string literal`%d`

src/transaction.cc

@@ -1492,9 +1492,8 @@ bool Transaction::intervention(ModSecurityIntervention *it) {
         it->status = m_it.status;
 
         if (m_it.log != NULL) {
-            std::string log("");
-            log.append(m_it.log);
-            utils::string::replaceAll(&log, std::string("%d"),
+            std::string log(m_it.log);
+            utils::string::replaceAll(log, "%d",
                 std::to_string(it->status));
             it->log = strdup(log.c_str());
         } else {

src/utils/string.cc

@@ -254,11 +254,11 @@ unsigned char *c2x(unsigned what, unsigned char *where) {
 }
 
 
-void replaceAll(std::string *str, const std::string& from,
-    const std::string& to) {
+void replaceAll(std::string &str, std::string_view from,
+    std::string_view to) {
     size_t start_pos = 0;
-    while ((start_pos = str->find(from, start_pos)) != std::string::npos) {
-        str->replace(start_pos, from.length(), to);
+    while ((start_pos = str.find(from, start_pos)) != std::string::npos) {
+        str.replace(start_pos, from.length(), to);
         start_pos += to.length();
     }
 }

src/utils/string.h

@@ -68,8 +68,8 @@ std::vector<std::string> ssplit(std::string str, char delimiter);
 std::pair<std::string, std::string> ssplit_pair(const std::string& str, char delimiter);
 std::vector<std::string> split(std::string str, char delimiter);
 void chomp(std::string *str);
-void replaceAll(std::string *str, const std::string& from,
-    const std::string& to);
+void replaceAll(std::string &str, std::string_view from,
+    std::string_view to);
 std::string removeWhiteSpacesIfNeeded(std::string a);
 std::string parserSanitizer(std::string a);