remove memcache::Trie from PrefixSelectorRoute (#441)

Summary:
Pull Request resolved: #441

migrating to LowerBoundPrefixMap

Reviewed By: udippant

Differential Revision: D53852214

fbshipit-source-id: c3646dd2dc1c7c5cbde256e9963706139d89417c

mcrouter/routes/PrefixSelectorRoute.h

@@ -16,7 +16,7 @@
 #include <folly/json/dynamic.h>
 
 #include "mcrouter/lib/config/RouteHandleFactory.h"
-#include "mcrouter/lib/fbi/cpp/Trie.h"
+#include "mcrouter/lib/fbi/cpp/LowerBoundPrefixMap.h"
 #include "mcrouter/lib/fbi/cpp/util.h"
 
 namespace facebook {
@@ -31,7 +31,7 @@ template <class RouteHandleIf>
 class PrefixSelectorRoute {
  public:
   /// Trie that acts like map from key prefix to corresponding RouteHandle.
-  Trie<std::shared_ptr<RouteHandleIf>> policies;
+  LowerBoundPrefixMap<std::shared_ptr<RouteHandleIf>> policies;
   /// Used when no RouteHandle found in policies
   std::shared_ptr<RouteHandleIf> wildcard;
 
@@ -64,9 +64,14 @@ class PrefixSelectorRoute {
       }
       // order is important
       std::sort(items.begin(), items.end());
+
+      typename LowerBoundPrefixMap<std::shared_ptr<RouteHandleIf>>::Builder
+          builder;
+      builder.reserve(items.size());
       for (const auto& it : items) {
-        policies.emplace(it.first, factory.create(*it.second));
+        builder.insert({std::string(it.first), factory.create(*it.second)});
       }
+      policies = std::move(builder).build();
     }
 
     if (jWildcard) {

mcrouter/routes/RoutePolicyMap-inl.h

@@ -60,9 +60,10 @@ RoutePolicyMap<RouteHandleIf>::RoutePolicyMap(
   // Combining routes for each key
   folly::F14FastSet<std::string_view> seen;
   for (const auto& cluster : clusters) {
-    for (const auto& [key, _] : cluster->policies) {
+    for (const auto& policy : cluster->policies) {
+      std::string_view key = policy.key();
       if (seen.insert(key).second) {
-        builder.insert({key, populateRoutesForKey(key, clusters)});
+        builder.insert({std::string(key), populateRoutesForKey(key, clusters)});
       }
     }
   }
@@ -104,7 +105,7 @@ auto RoutePolicyMap<RouteHandleIf>::populateRoutesForKey(
   for (const auto& cluster : clusters) {
     auto found = cluster->policies.findPrefix(key);
     const SharedRoutePtr& ptr =
-        found == cluster->policies.end() ? cluster->wildcard : found->second;
+        found == cluster->policies.end() ? cluster->wildcard : found->value();
     if (ptr && seen.insert(ptr.get()).second) {
       res.push_back(ptr);
     }

mcrouter/routes/test/PrefixSelectorRouteTest.cpp

@@ -41,7 +41,7 @@ void constructionTest(
   };
   std::vector<std::pair<std::string, RouteHandle>> policies;
   for (const auto& p : route.policies) {
-    policies.emplace_back(std::string(p.first), toInt(p.second));
+    policies.emplace_back(std::string(p.key()), toInt(p.value()));
   }
 
   EXPECT_EQ(expected.wildcard, toInt(route.wildcard));

mcrouter/routes/test/RoutePolicyMapTest.cpp

@@ -40,9 +40,11 @@ struct MockPrefixSelectorRoute {
       res->wildcard = kRouteHandles[*wildcard];
     }
 
+    LowerBoundPrefixMap<std::shared_ptr<RouteHandle>>::Builder builder;
     for (const auto& [k, v] : policies) {
-      res->policies.emplace(k, kRouteHandles[v]);
+      builder.insert({k, kRouteHandles[v]});
     }
+    res->policies = std::move(builder).build();
 
     return res;
   }