Cancel album cover loads properly

src/covers/albumcoverfetcher.cpp

@@ -69,6 +69,12 @@ void AlbumCoverFetcher::AddRequest(const CoverSearchRequest& req) {
 
 void AlbumCoverFetcher::Clear() {
   queued_requests_.clear();
+
+  foreach (AlbumCoverFetcherSearch* search, active_requests_.values()) {
+    search->Cancel();
+    search->deleteLater();
+  }
+  active_requests_.clear();
 }
 
 void AlbumCoverFetcher::StartRequests() {

src/covers/albumcoverfetchersearch.cpp

@@ -40,7 +40,8 @@ AlbumCoverFetcherSearch::AlbumCoverFetcherSearch(const CoverSearchRequest& reque
   : QObject(parent),
     request_(request),
     image_load_timeout_(new NetworkTimeouts(kImageLoadTimeoutMs, this)),
-    network_(network)
+    network_(network),
+    cancel_requested_(false)
 {
   // we will terminate the search after kSearchTimeoutMs miliseconds if we are not
   // able to find all of the results before that point in time
@@ -108,6 +109,10 @@ void AlbumCoverFetcherSearch::ProviderSearchFinished(
 }
 
 void AlbumCoverFetcherSearch::AllProvidersFinished() {
+  if (cancel_requested_) {
+    return;
+  }
+
   // if we only wanted to do the search then we're done
   if (request_.search) {
     emit SearchFinished(request_.id, results_);
@@ -159,6 +164,10 @@ void AlbumCoverFetcherSearch::ProviderCoverFetchFinished() {
   reply->deleteLater();
   pending_image_loads_.removeAll(reply);
 
+  if (cancel_requested_) {
+    return;
+  }
+
   if (reply->error() != QNetworkReply::NoError) {
     qLog(Info) << "Error requesting" << reply->url() << reply->errorString();
   } else {
@@ -216,3 +225,16 @@ void AlbumCoverFetcherSearch::SendBestImage() {
 
   emit AlbumCoverFetched(request_.id, image);
 }
+
+void AlbumCoverFetcherSearch::Cancel() {
+  cancel_requested_ = true;
+
+  if (!pending_requests_.isEmpty()) {
+    TerminateSearch();
+  } else if (!pending_image_loads_.isEmpty()) {
+    foreach (QNetworkReply* reply, pending_image_loads_) {
+      reply->abort();
+    }
+    pending_image_loads_.clear();
+  }
+}

src/covers/albumcoverfetchersearch.h

@@ -39,10 +39,12 @@ class AlbumCoverFetcherSearch : public QObject {
   AlbumCoverFetcherSearch(const CoverSearchRequest& request,
                           QNetworkAccessManager* network, QObject* parent);
 
-  // Starts the search. This is the moment when we count cover providers available
-  // in the application.
   void Start();
 
+  // Cancels all pending requests.  No Finished signals will be emitted, and it
+  // is the caller's responsibility to delete the AlbumCoverFetcherSearch.
+  void Cancel();
+
 signals:
   // It's the end of search (when there was no fetch-me-a-cover request).
   void SearchFinished(quint64, const CoverSearchResults& results);
@@ -81,6 +83,8 @@ private:
   QMap<float, QImage> candidate_images_;
 
   QNetworkAccessManager* network_;
+
+  bool cancel_requested_;
 };
 
 #endif  // ALBUMCOVERFETCHERSEARCH_H