Avoid vector overhead in isSupportedScheme.

Summary:
1) using vector is inefficient since it's heap-allocated and has indirection
2) using string is inefficient for similar reasons
3) using static for supported schemes is inefficient because it involves atomics or mutex to ensure thread safety
4) using folly::StringPiece provides more ergonomic APIs for `contains` and `starts_with`

Reviewed By: hanidamlaj

Differential Revision: D74557531

fbshipit-source-id: 2364bdbe9cd5aa6b292ad66a4d2ab461f6f890b8

Author: ttsugriy

proxygen/lib/utils/ParseURL.cpp

@@ -52,21 +52,19 @@ static bool validateScheme(folly::StringPiece url) {
       scheme.begin(), scheme.end(), [](auto _) { return std::isalpha(_); });
 }
 
-bool ParseURL::isSupportedScheme(const std::string& location) {
-  static const std::vector<std::string> supportedSchemes = {"http", "https"};
-  std::size_t containsScheme = location.find("://");
-  if (containsScheme == std::string::npos) {
+bool ParseURL::isSupportedScheme(folly::StringPiece location) {
+  static constexpr std::array<folly::StringPiece, 2> kSupportedSchemes{"http",
+                                                                       "https"};
+  if (!location.contains("://")) {
     // Location doesn't contain a scheme, so use the one from the original URL
     return true;
   }
 
-  for (const std::string& scheme : supportedSchemes) {
-    // Check to see whether or not it is a supported scheme
-    if (location.compare(0, scheme.length(), scheme) == 0) {
-      return true;
-    }
-  }
-  return false;
+  return std::any_of(kSupportedSchemes.begin(),
+                     kSupportedSchemes.end(),
+                     [location](folly::StringPiece scheme) {
+                       return location.starts_with(scheme);
+                     });
 }
 
 folly::Optional<std::string> ParseURL::getRedirectDestination(

proxygen/lib/utils/ParseURL.h

@@ -47,7 +47,7 @@ class ParseURL {
     return ParseURL(urlVal, strict);
   }
 
-  static bool isSupportedScheme(const std::string& location);
+  static bool isSupportedScheme(folly::StringPiece location);
 
   static folly::Optional<std::string> getRedirectDestination(
       folly::StringPiece url,