From 13ac7ff493583f11b9a0c4dfea9e8ae8220e2585 Mon Sep 17 00:00:00 2001
From: Ashton Larkin <ashton@openrobotics.org>
Date: Fri, 9 Apr 2021 12:19:12 -0400
Subject: [PATCH] use unordered maps for component lookups in views

Signed-off-by: Ashton Larkin <ashton@openrobotics.org>
---
 .../gazebo/detail/ComponentStorageBase.hh     |  4 +--
 include/ignition/gazebo/detail/View.hh        | 29 +++++++++++++++++--
 2 files changed, 28 insertions(+), 5 deletions(-)

diff --git a/include/ignition/gazebo/detail/ComponentStorageBase.hh b/include/ignition/gazebo/detail/ComponentStorageBase.hh
index ca9e5e8960..f095704884 100644
--- a/include/ignition/gazebo/detail/ComponentStorageBase.hh
+++ b/include/ignition/gazebo/detail/ComponentStorageBase.hh
@@ -17,7 +17,7 @@
 #ifndef IGNITION_GAZEBO_DETAIL_COMPONENTSTORAGEBASE_HH_
 #define IGNITION_GAZEBO_DETAIL_COMPONENTSTORAGEBASE_HH_
 
-#include <map>
+#include <unordered_map>
 #include <utility>
 #include <vector>
 #include "ignition/gazebo/components/Component.hh"
@@ -212,7 +212,7 @@ namespace ignition
       private: ComponentId idCounter = 0;
 
       /// \brief Map of ComponentId to Components (see the components vector).
-      private: std::map<ComponentId, int> idMap;
+      private: std::unordered_map<ComponentId, int> idMap;
 
       /// \brief Sequential storage of components.
       public: std::vector<ComponentTypeT> components;
diff --git a/include/ignition/gazebo/detail/View.hh b/include/ignition/gazebo/detail/View.hh
index 654a146291..f3b9ed327c 100644
--- a/include/ignition/gazebo/detail/View.hh
+++ b/include/ignition/gazebo/detail/View.hh
@@ -17,9 +17,9 @@
 #ifndef IGNITION_GAZEBO_DETAIL_VIEW_HH_
 #define IGNITION_GAZEBO_DETAIL_VIEW_HH_
 
-#include <map>
 #include <set>
 #include <string>
+#include <unordered_map>
 #include <utility>
 #include "ignition/gazebo/components/Component.hh"
 #include "ignition/gazebo/Entity.hh"
@@ -126,9 +126,32 @@ class IGNITION_GAZEBO_VISIBLE View
   /// \brief List of entities about to be removed
   public: std::set<Entity> toRemoveEntities;
 
+  /// \brief Hash functor for std::pair<Entity, ComponentTypeId>
+  public: struct Hasher
+          {
+            std::size_t operator()(
+                std::pair<Entity, ComponentTypeId> _pair) const
+            {
+              _pair.first ^= _pair.second + 0x9e3779b9 + (_pair.second << 6)
+                 + (_pair.second >> 2);
+              return _pair.first;
+            }
+          };
+
+  /// \brief Equality functor for std::pair<Entity, ComponentTypeId>
+  public: struct EqualTo
+          {
+            bool operator()(const std::pair<Entity, ComponentTypeId> &_lhs,
+                const std::pair<Entity, ComponentTypeId> &_rhs) const
+            {
+              return _lhs.first == _rhs.first &&
+                _lhs.second == _rhs.second;
+            }
+          };
+
   /// \brief All of the components for each entity.
-  public: std::map<std::pair<Entity, ComponentTypeId>,
-          ComponentId> components;
+  public: std::unordered_map<std::pair<Entity, ComponentTypeId>, ComponentId,
+            Hasher, EqualTo> components;
 };
 /// \endcond
 }