From 04406a3c8ecd5bb21521b939b874db4aa192c5db Mon Sep 17 00:00:00 2001
From: Alexander Krotov <krotov@iitp.ru>
Date: Fri, 4 May 2018 13:08:29 +0300
Subject: [PATCH] wifi: Replace linear search with map lookup in
 MinstrelHtWifiManager

---
 src/wifi/model/minstrel-ht-wifi-manager.cc | 28 +++++++---------------
 src/wifi/model/minstrel-ht-wifi-manager.h  |  3 +--
 2 files changed, 9 insertions(+), 22 deletions(-)

diff --git a/src/wifi/model/minstrel-ht-wifi-manager.cc b/src/wifi/model/minstrel-ht-wifi-manager.cc
index 97695ca1a..2cd01a1af 100644
--- a/src/wifi/model/minstrel-ht-wifi-manager.cc
+++ b/src/wifi/model/minstrel-ht-wifi-manager.cc
@@ -339,44 +339,32 @@ Time
 MinstrelHtWifiManager::GetFirstMpduTxTime (uint32_t groupId, WifiMode mode) const
 {
   NS_LOG_FUNCTION (this << groupId << mode);
-  for (TxTime::const_iterator i = m_minstrelGroups[groupId].ratesFirstMpduTxTimeTable.begin (); i != m_minstrelGroups[groupId].ratesFirstMpduTxTimeTable.end (); i++)
-    {
-      if (mode == i->second)
-        {
-          return i->first;
-        }
-    }
-  NS_ASSERT (false);
-  return Seconds (0);
+  auto it = m_minstrelGroups[groupId].ratesFirstMpduTxTimeTable.find (mode);
+  NS_ASSERT (it != m_minstrelGroups[groupId].ratesFirstMpduTxTimeTable.end ());
+  return it->second;
 }
 
 void
 MinstrelHtWifiManager::AddFirstMpduTxTime (uint32_t groupId, WifiMode mode, Time t)
 {
   NS_LOG_FUNCTION (this << groupId << mode << t);
-  m_minstrelGroups[groupId].ratesFirstMpduTxTimeTable.push_back (std::make_pair (t, mode));
+  m_minstrelGroups[groupId].ratesFirstMpduTxTimeTable.insert (std::make_pair (mode, t));
 }
 
 Time
 MinstrelHtWifiManager::GetMpduTxTime (uint32_t groupId, WifiMode mode) const
 {
   NS_LOG_FUNCTION (this << groupId << mode);
-  for (TxTime::const_iterator i = m_minstrelGroups[groupId].ratesTxTimeTable.begin (); i != m_minstrelGroups[groupId].ratesTxTimeTable.end (); i++)
-    {
-      if (mode == i->second)
-        {
-          return i->first;
-        }
-    }
-  NS_ASSERT (false);
-  return Seconds (0);
+  auto it = m_minstrelGroups[groupId].ratesTxTimeTable.find (mode);
+  NS_ASSERT (it != m_minstrelGroups[groupId].ratesTxTimeTable.end ());
+  return it->second;
 }
 
 void
 MinstrelHtWifiManager::AddMpduTxTime (uint32_t groupId, WifiMode mode, Time t)
 {
   NS_LOG_FUNCTION (this << groupId << mode << t);
-  m_minstrelGroups[groupId].ratesTxTimeTable.push_back (std::make_pair (t, mode));
+  m_minstrelGroups[groupId].ratesTxTimeTable.insert (std::make_pair (mode, t));
 }
 
 WifiRemoteStation *
diff --git a/src/wifi/model/minstrel-ht-wifi-manager.h b/src/wifi/model/minstrel-ht-wifi-manager.h
index 077c9e014..c386b3f50 100644
--- a/src/wifi/model/minstrel-ht-wifi-manager.h
+++ b/src/wifi/model/minstrel-ht-wifi-manager.h
@@ -33,9 +33,8 @@ namespace ns3 {
 
 /**
  * Data structure to save transmission time calculations per rate.
- * A vector of Time, WifiMode pairs.
  */
-typedef std::vector<std::pair<Time, WifiMode> > TxTime;
+typedef std::map<WifiMode, Time> TxTime;
 
 /**
  * Data structure to contain the information that defines a group.