Avoid simultaneous access of the same file for two diffrent width

src/library/coverartcache.cpp

@@ -157,12 +157,11 @@ void CoverArtCache::tryLoadCover(
         return;
     }
 
-    const auto requestedCacheKey = coverInfo.cacheKey();
-    QString cacheKey = pixmapCacheKey(requestedCacheKey, desiredWidth);
+    const mixxx::cache_key_t requestedCacheKey = coverInfo.cacheKey();
     // keep a list of cacheKeys for which a future is currently running
     // to avoid loading the same picture again while we are loading it
-    bool requestPending = m_runningRequests.contains(cacheKey);
-    m_runningRequests.insert(cacheKey, pRequester);
+    bool requestPending = m_runningRequests.contains(requestedCacheKey);
+    m_runningRequests.insert(requestedCacheKey, {pRequester, desiredWidth});
     if (requestPending) {
         return;
     }
@@ -294,11 +293,21 @@ void CoverArtCache::coverLoaded() {
         }
     }
 
-    const QObject* pRequester;
-    while ((pRequester = m_runningRequests.take(cacheKey)) != nullptr) {
-        emit coverFound(
-                pRequester,
+    QMultiHash<QString, int>::iterator i = m_runningRequests.find(res.coverArt.cacheKey());
+    while (i != hash.end() && i.key() == res.coverArt.cacheKey()) {
+        if (i.value().desiredWidth == res.coverArt.resizedToWidth) {
+            emit coverFound(
+                    i.value().pRequester,
+                    res.coverArt,
+                    pixmap);
+        } else {
+            tryLoadCover(
+                i.value().pRequester,
+                nullptr,
                 res.coverArt,
-                pixmap);
+                res.coverArt.resizedToWidth);
+        }
+        hash.erase(i);
+        ++i;
     }
 }

src/library/coverartcache.h

@@ -92,5 +92,12 @@ class CoverArtCache : public QObject, public Singleton<CoverArtCache> {
             const CoverInfo& info,
             int desiredWidth);
 
-    QMultiHash<QString, const QObject*> m_runningRequests;
+    struct RequestData {
+        const QObject* pRequester;
+        int desiredWidth;
+    } 
+    bool operator==(const RequestData& l, const RequestData& r) {
+        return l.pRequester == r.pRequester && l.desiredWidth == r.desiredWidth;
+    }
+    QMultiHash<mixxx::cache_key_t, RequestData> m_runningRequests;
 };