From eb64ea9fc7131f26d4da8bbb6509dcb933def443 Mon Sep 17 00:00:00 2001
From: Peter Johnson <johnson.peter@gmail.com>
Date: Sat, 28 Jul 2018 03:04:41 -0700
Subject: [PATCH] MotorSafetyHelper: Use SmallPtrSet instead of std::set

---
 .../src/main/native/cpp/MotorSafetyHelper.cpp   | 17 +++++++++--------
 .../main/native/include/frc/MotorSafetyHelper.h |  8 --------
 2 files changed, 9 insertions(+), 16 deletions(-)

diff --git a/wpilibc/src/main/native/cpp/MotorSafetyHelper.cpp b/wpilibc/src/main/native/cpp/MotorSafetyHelper.cpp
index 8e892bd95f..e2f0351aa6 100644
--- a/wpilibc/src/main/native/cpp/MotorSafetyHelper.cpp
+++ b/wpilibc/src/main/native/cpp/MotorSafetyHelper.cpp
@@ -7,6 +7,7 @@
 
 #include "frc/MotorSafetyHelper.h"
 
+#include <wpi/SmallPtrSet.h>
 #include <wpi/SmallString.h>
 #include <wpi/raw_ostream.h>
 
@@ -17,8 +18,8 @@
 
 using namespace frc;
 
-std::set<MotorSafetyHelper*> MotorSafetyHelper::m_helperList;
-wpi::mutex MotorSafetyHelper::m_listMutex;
+static wpi::SmallPtrSet<MotorSafetyHelper*, 32> helperList;
+static wpi::mutex listMutex;
 
 MotorSafetyHelper::MotorSafetyHelper(MotorSafety* safeObject)
     : m_safeObject(safeObject) {
@@ -26,13 +27,13 @@ MotorSafetyHelper::MotorSafetyHelper(MotorSafety* safeObject)
   m_expiration = DEFAULT_SAFETY_EXPIRATION;
   m_stopTime = Timer::GetFPGATimestamp();
 
-  std::lock_guard<wpi::mutex> lock(m_listMutex);
-  m_helperList.insert(this);
+  std::lock_guard<wpi::mutex> lock(listMutex);
+  helperList.insert(this);
 }
 
 MotorSafetyHelper::~MotorSafetyHelper() {
-  std::lock_guard<wpi::mutex> lock(m_listMutex);
-  m_helperList.erase(this);
+  std::lock_guard<wpi::mutex> lock(listMutex);
+  helperList.erase(this);
 }
 
 void MotorSafetyHelper::Feed() {
@@ -89,8 +90,8 @@ bool MotorSafetyHelper::IsSafetyEnabled() const {
 }
 
 void MotorSafetyHelper::CheckMotors() {
-  std::lock_guard<wpi::mutex> lock(m_listMutex);
-  for (auto elem : m_helperList) {
+  std::lock_guard<wpi::mutex> lock(listMutex);
+  for (auto elem : helperList) {
     elem->Check();
   }
 }
diff --git a/wpilibc/src/main/native/include/frc/MotorSafetyHelper.h b/wpilibc/src/main/native/include/frc/MotorSafetyHelper.h
index eb53917a37..8fbe91ba79 100644
--- a/wpilibc/src/main/native/include/frc/MotorSafetyHelper.h
+++ b/wpilibc/src/main/native/include/frc/MotorSafetyHelper.h
@@ -7,8 +7,6 @@
 
 #pragma once
 
-#include <set>
-
 #include <wpi/mutex.h>
 
 #include "frc/ErrorBase.h"
@@ -114,12 +112,6 @@ class MotorSafetyHelper : public ErrorBase {
 
   // The object that is using the helper
   MotorSafety* m_safeObject;
-
-  // List of all existing MotorSafetyHelper objects.
-  static std::set<MotorSafetyHelper*> m_helperList;
-
-  // Protect accesses to the list of helpers
-  static wpi::mutex m_listMutex;
 };
 
 }  // namespace frc