Improve Item request processing (#13)

Currently the addon isn't correctly tracking when an item doesn't exist. This is causing an excessive number of item info queries when logging in, since the same items are being checked repeatedly.

Testing was done on Classic Era, logging in for the first time after restarting the game.
Before changes, I recorded 242 GET_ITEM_INFO_RECEIVED events over ~85 seconds when the addon loads.
After changes, I recorded 30 GET_ITEM_INFO_RECEIVED events over ~5 seconds when the addon loads.

I've also tested changes on Wrath, but not Retail. As far as I know, the ItemMixin API is unchanged in all game versions.

LibRangeCheck-3.0/LibRangeCheck-3.0.lua

@@ -40,7 +40,7 @@ License: MIT
 -- @class file
 -- @name LibRangeCheck-3.0
 local MAJOR_VERSION = "LibRangeCheck-3.0"
-local MINOR_VERSION = 9
+local MINOR_VERSION = 10
 
 ---@class lib
 local lib, oldminor = LibStub:NewLibrary(MAJOR_VERSION, MINOR_VERSION)
@@ -524,8 +524,8 @@ end
 
 -- temporary stuff
 
-local pendingItemRequest
-local itemRequestTimeoutAt
+local pendingItemRequest = {}
+local itemRequestTimeoutAt = {}
 local foundNewItems
 local cacheAllItems
 local friendItemRequests
@@ -675,7 +675,7 @@ local function createCheckerList(spellList, itemList, interactList)
     for range, items in pairs(itemList) do
       for i = 1, #items do
         local item = items[i]
-        if GetItemInfo(item) then
+        if Item:CreateFromItemID(item):IsItemDataCached() and GetItemInfo(item) then
           addChecker(res, range, nil, checkers_Item[item], "item:" .. item)
           break
         end
@@ -1238,8 +1238,9 @@ end
 
 function lib:GET_ITEM_INFO_RECEIVED(event, item, success)
   -- print("### GET_ITEM_INFO_RECEIVED: " .. tostring(item) .. ", " .. tostring(success))
-  if item == pendingItemRequest then
-    pendingItemRequest = nil
+  if pendingItemRequest[item] then
+    pendingItemRequest[item] = nil
+    itemRequestTimeoutAt[item] = nil
     if not success then
       self.failedItemRequests[item] = true
     end
@@ -1258,40 +1259,40 @@ function lib:processItemRequests(itemRequests)
       if not i then
         itemRequests[range] = nil
         break
-      elseif self.failedItemRequests[item] then
+      elseif Item:CreateFromItemID(item):IsItemEmpty() or self.failedItemRequests[item] then
         -- print("### processItemRequests: failed: " .. tostring(item))
         tremove(items, i)
-      elseif item == pendingItemRequest and GetTime() < itemRequestTimeoutAt then
+      elseif pendingItemRequest[item] and GetTime() < itemRequestTimeoutAt[item] then
         return true -- still waiting for server response
       elseif GetItemInfo(item) then
         -- print("### processItemRequests: found: " .. tostring(item))
-        if itemRequestTimeoutAt then
+        if itemRequestTimeoutAt[item] then
           -- print("### processItemRequests: new: " .. tostring(item))
           foundNewItems = true
-          itemRequestTimeoutAt = nil
-          pendingItemRequest = nil
+          itemRequestTimeoutAt[item] = nil
+          pendingItemRequest[item] = nil
         end
         if not cacheAllItems then
           itemRequests[range] = nil
           break
         end
         tremove(items, i)
-      elseif not itemRequestTimeoutAt then
+      elseif not itemRequestTimeoutAt[item] then
         -- print("### processItemRequests: waiting: " .. tostring(item))
-        itemRequestTimeoutAt = GetTime() + ItemRequestTimeout
-        pendingItemRequest = item
+        itemRequestTimeoutAt[item] = GetTime() + ItemRequestTimeout
+        pendingItemRequest[item] = true
         if not self.frame:IsEventRegistered("GET_ITEM_INFO_RECEIVED") then
           self.frame:RegisterEvent("GET_ITEM_INFO_RECEIVED")
         end
         return true
-      elseif GetTime() >= itemRequestTimeoutAt then
+      elseif GetTime() >= itemRequestTimeoutAt[item] then
         -- print("### processItemRequests: timeout: " .. tostring(item))
         if cacheAllItems then
           print(MAJOR_VERSION .. ": timeout for item: " .. tostring(item))
         end
         self.failedItemRequests[item] = true
-        itemRequestTimeoutAt = nil
-        pendingItemRequest = nil
+        itemRequestTimeoutAt[item] = nil
+        pendingItemRequest[item] = nil
         tremove(items, i)
       else
         return true -- still waiting for server response