Added lock to GetStaleOfferIds

Made `RagfairRequiredItemService` a singleton
Made `RagfairRequiredItemService ` store offerIds instead of offer objects, reducing memory footprint
Reworked `GetOffersThatRequireItem` to work with `RagfairRequiredItemService` changes
Moved `GenerateDynamicOffers` to run after garbage colelction, this means GC will work on memory prior to new offers being added but after stale offers are removed

Made `PaymentHelper` a singleton + Store currency tpls in a hashset instead of list

Comment improvements

Libraries/SPTarkov.Server.Core/Helpers/PaymentHelper.cs

@@ -5,23 +5,28 @@ using SPTarkov.Server.Core.Servers;
 
 namespace SPTarkov.Server.Core.Helpers;
 
-[Injectable]
-public class PaymentHelper(ConfigServer _configServer)
+[Injectable(InjectionType.Singleton)]
+public class PaymentHelper(ConfigServer configServer)
 {
     protected bool _addedCustomMoney;
-    protected InventoryConfig _inventoryConfig = _configServer.GetConfig<InventoryConfig>();
-    protected List<string> _moneyTpls = [Money.DOLLARS, Money.EUROS, Money.ROUBLES, Money.GP];
+    protected readonly InventoryConfig _inventoryConfig = configServer.GetConfig<InventoryConfig>();
+    protected readonly HashSet<string> _moneyTpls = [Money.DOLLARS, Money.EUROS, Money.ROUBLES, Money.GP];
 
     /// <summary>
     ///     Is the passed in tpl money (also checks custom currencies in inventoryConfig.customMoneyTpls)
     /// </summary>
-    /// <param name="tpl"></param>
+    /// <param name="tpl">Item Tpl to check</param>
     /// <returns></returns>
     public bool IsMoneyTpl(string tpl)
     {
+        // Add custom currency first time this method is accessed
         if (!_addedCustomMoney)
         {
-            _moneyTpls.AddRange(_inventoryConfig.CustomMoneyTpls);
+            foreach (var customMoney in _inventoryConfig.CustomMoneyTpls)
+            {
+                _moneyTpls.Add(customMoney);
+            }
+            
             _addedCustomMoney = true;
         }
 
@@ -32,7 +37,7 @@ public class PaymentHelper(ConfigServer _configServer)
     ///     Gets currency TPL from TAG
     /// </summary>
     /// <param name="currency"></param>
-    /// <returns></returns>
+    /// <returns>Tpl of currency</returns>
     public string GetCurrency(CurrencyType? currency)
     {
         return currency switch
@@ -41,7 +46,7 @@ public class PaymentHelper(ConfigServer _configServer)
             CurrencyType.USD => Money.DOLLARS,
             CurrencyType.RUB => Money.ROUBLES,
             CurrencyType.GP => Money.GP,
-            _ => ""
+            _ => string.Empty
         };
     }
 }

Libraries/SPTarkov.Server.Core/Helpers/RagfairOfferHelper.cs

@@ -168,31 +168,30 @@ public class RagfairOfferHelper(
     public List<RagfairOffer> GetOffersThatRequireItem(SearchRequestData searchRequest, PmcData pmcData)
     {
         // Get all offers that require the desired item and filter out offers from non traders if player below ragfair unlock
-        var requiredOffers = _ragfairRequiredItemsService.GetRequiredItemsById(searchRequest.NeededSearchId);
+        var offerIDsForItem = _ragfairRequiredItemsService.GetRequiredOffersById(searchRequest.NeededSearchId);
 
         var tieredFlea = _ragfairConfig.TieredFlea;
         var tieredFleaLimitTypes = tieredFlea.UnlocksType;
-        return requiredOffers.Where(offer =>
-                {
-                    if (!PassesSearchFilterCriteria(searchRequest, offer, pmcData))
-                    {
-                        return false;
-                    }
 
-                    if (tieredFlea.Enabled && !OfferIsFromTrader(offer))
-                    {
-                        CheckAndLockOfferFromPlayerTieredFlea(
-                            tieredFlea,
-                            offer,
-                            tieredFleaLimitTypes.Keys.ToList(),
-                            pmcData.Info.Level.Value
-                        );
-                    }
+        var result = new List<RagfairOffer>();
+        foreach (var offer in offerIDsForItem
+                     .Select(_ragfairOfferService.GetOfferByOfferId)
+                     .Where(offer => PassesSearchFilterCriteria(searchRequest, offer, pmcData)))
+        {
+            if (tieredFlea.Enabled && !OfferIsFromTrader(offer))
+            {
+                CheckAndLockOfferFromPlayerTieredFlea(
+                    tieredFlea,
+                    offer,
+                    tieredFleaLimitTypes.Keys.ToList(),
+                    pmcData.Info.Level.Value
+                );
+            }
 
-                    return true;
-                }
-            )
-            .ToList();
+            result.Add(offer);
+        }
+
+        return result;
     }
 
     /// <summary>

Libraries/SPTarkov.Server.Core/Servers/RagfairServer.cs

@@ -57,11 +57,13 @@ public class RagfairServer(
             // Must occur BEFORE "RemoveExpiredOffers"
             var expiredAssortsWithChildren = _ragfairOfferHolder.GetExpiredOfferItems();
 
+            _ragfairOfferService.RemoveExpiredOffers();
+
+            // Force a cleanup+compact now all the expired offers are gone
+            GC.Collect(GC.MaxGeneration, GCCollectionMode.Optimized, true, true);
+
             // Replace the expired offers with new ones
             _ragfairOfferGenerator.GenerateDynamicOffers(expiredAssortsWithChildren);
-
-            _ragfairOfferService.RemoveExpiredOffers();
-            GC.Collect(GC.MaxGeneration, GCCollectionMode.Optimized, true, true);
         }
 
         _ragfairRequiredItemsService.BuildRequiredItemTable();

Libraries/SPTarkov.Server.Core/Services/RagfairRequiredItemsService.cs

@@ -1,34 +1,44 @@
 using System.Collections.Concurrent;
 using SPTarkov.DI.Annotations;
 using SPTarkov.Server.Core.Helpers;
-using SPTarkov.Server.Core.Models.Eft.Ragfair;
 
 namespace SPTarkov.Server.Core.Services;
 
 [Injectable(InjectionType.Singleton)]
 public class RagfairRequiredItemsService(
-    RagfairOfferService _ragfairOfferService,
-    PaymentHelper _paymentHelper)
+    RagfairOfferService ragfairOfferService,
+    PaymentHelper paymentHelper)
 {
-    protected ConcurrentDictionary<string, List<RagfairOffer>> _requiredItemsCache = new();
+    /// <summary>
+    /// Key = tpl
+    /// </summary>
+    protected readonly ConcurrentDictionary<string, HashSet<string>> _requiredItemsCache = new();
 
-    public List<RagfairOffer> GetRequiredItemsById(string searchId)
+    /// <summary>
+    /// Get the offerId of offers that require the supplied tpl
+    /// </summary>
+    /// <param name="tpl">Tpl to find offers ids for</param>
+    /// <returns></returns>
+    public HashSet<string> GetRequiredOffersById(string tpl)
     {
-        if (_requiredItemsCache.TryGetValue(searchId, out var list))
+        if (_requiredItemsCache.TryGetValue(tpl, out var offerIds))
         {
-            return list;
+            return offerIds;
         }
 
         return [];
     }
 
+    /// <summary>
+    /// Create a cache of requirements to purchase item
+    /// </summary>
     public void BuildRequiredItemTable()
     {
         _requiredItemsCache.Clear();
-        foreach (var offer in _ragfairOfferService.GetOffers())
+        foreach (var offer in ragfairOfferService.GetOffers())
         foreach (var requirement in offer.Requirements)
         {
-            if (_paymentHelper.IsMoneyTpl(requirement.Template))
+            if (paymentHelper.IsMoneyTpl(requirement.Template))
                 // This would just be too noisy
             {
                 continue;
@@ -38,7 +48,7 @@ public class RagfairRequiredItemsService(
             _requiredItemsCache.TryAdd(requirement.Template, []);
 
             // Add matching offer
-            _requiredItemsCache.GetValueOrDefault(requirement.Template)?.Add(offer);
+            _requiredItemsCache.GetValueOrDefault(requirement.Template)?.Add(offer.Id);
         }
     }
 }

Libraries/SPTarkov.Server.Core/Utils/RagfairOfferHolder.cs

@@ -42,7 +42,10 @@ public class RagfairOfferHolder(
     /// <returns>RagfairOffer</returns>
     public HashSet<string> GetStaleOfferIds()
     {
-        return _expiredOfferIds;
+        lock (_expiredOfferIdsLock)
+        {
+            return _expiredOfferIds;
+        }
     }
 
     /// <summary>
@@ -90,7 +93,7 @@ public class RagfairOfferHolder(
     /// <returns>RagfairOffer list</returns>
     public List<RagfairOffer> GetOffers()
     {
-        if (_offersById.Count > 0)
+        if (!_offersById.IsEmpty)
         {
             return _offersById.Values.ToList();
         }
@@ -342,7 +345,7 @@ public class RagfairOfferHolder(
     }
 
     /// <summary>
-    ///     Flag offers with an expiry before the passed in timestamp
+    ///     Flag offers with a end date set before the passed in timestamp
     /// </summary>
     /// <param name="timestamp">Timestamp at point offer is 'expired'</param>
     public void FlagExpiredOffersAfterDate(long timestamp)