From 36eaea466ebe019de21940502653380e20a5862d Mon Sep 17 00:00:00 2001
From: Dan Paulat <dpaulat@gmail.com>
Date: Sun, 9 Oct 2022 00:27:54 -0500
Subject: [PATCH] Garbage collect unused radar product manager instances

---
 .../scwx/qt/manager/radar_product_manager.cpp | 21 +++++++++++------
 .../scwx/qt/model/radar_product_model.cpp     | 23 ++++++++++++-------
 2 files changed, 29 insertions(+), 15 deletions(-)

diff --git a/scwx-qt/source/scwx/qt/manager/radar_product_manager.cpp b/scwx-qt/source/scwx/qt/manager/radar_product_manager.cpp
index 65ebe214..a5a6987f 100644
--- a/scwx-qt/source/scwx/qt/manager/radar_product_manager.cpp
+++ b/scwx-qt/source/scwx/qt/manager/radar_product_manager.cpp
@@ -50,8 +50,7 @@ static const std::string kDefaultLevel3Product_ {"N0B"};
 
 static constexpr std::chrono::seconds kRetryInterval_ {15};
 
-// TODO: Find a way to garbage collect this
-static std::unordered_map<std::string, std::shared_ptr<RadarProductManager>>
+static std::unordered_map<std::string, std::weak_ptr<RadarProductManager>>
                   instanceMap_;
 static std::mutex instanceMutex_;
 
@@ -960,14 +959,22 @@ RadarProductManager::Instance(const std::string& radarSite)
    {
       std::lock_guard<std::mutex> guard(instanceMutex_);
 
-      if (!instanceMap_.contains(radarSite))
+      // Look up instance weak pointer
+      auto it = instanceMap_.find(radarSite);
+      if (it != instanceMap_.end())
       {
-         instanceMap_[radarSite] =
-            std::make_shared<RadarProductManager>(radarSite);
-         instanceCreated = true;
+         // Attempt to convert the weak pointer to a shared pointer. It may have
+         // been garbage collected.
+         instance = it->second.lock();
       }
 
-      instance = instanceMap_[radarSite];
+      // If no active instance was found, create a new one
+      if (instance == nullptr)
+      {
+         instance = std::make_shared<RadarProductManager>(radarSite);
+         instanceMap_.insert_or_assign(radarSite, instance);
+         instanceCreated = true;
+      }
    }
 
    if (instanceCreated)
diff --git a/scwx-qt/source/scwx/qt/model/radar_product_model.cpp b/scwx-qt/source/scwx/qt/model/radar_product_model.cpp
index bb4ecebd..e2e158b0 100644
--- a/scwx-qt/source/scwx/qt/model/radar_product_model.cpp
+++ b/scwx-qt/source/scwx/qt/model/radar_product_model.cpp
@@ -50,17 +50,24 @@ RadarProductModelImpl::RadarProductModelImpl(RadarProductModel* self) :
       {
          logger_->debug("Adding radar site: {}", radarSite);
 
-         const QModelIndex rootIndex =
-            self_->createIndex(rootItem_->row(), 0, rootItem_.get());
-         const int rootChildren = rootItem_->child_count();
+         const QString radarSiteName {QString::fromStdString(radarSite)};
 
-         self_->beginInsertRows(rootIndex, rootChildren, rootChildren);
+         // Find existing radar site item (e.g., KLSX, KEAX)
+         TreeItem* radarSiteItem = rootItem_->FindChild(0, radarSiteName);
 
-         TreeItem* radarSiteItem =
-            new TreeItem({QString::fromStdString(radarSite)});
-         rootItem_->AppendChild(radarSiteItem);
+         if (radarSiteItem == nullptr)
+         {
+            const QModelIndex rootIndex =
+               self_->createIndex(rootItem_->row(), 0, rootItem_.get());
+            const int rootChildren = rootItem_->child_count();
 
-         self_->endInsertRows();
+            self_->beginInsertRows(rootIndex, rootChildren, rootChildren);
+
+            radarSiteItem = new TreeItem({radarSiteName});
+            rootItem_->AppendChild(radarSiteItem);
+
+            self_->endInsertRows();
+         }
 
          connect(
             manager::RadarProductManager::Instance(radarSite).get(),