Merge pull request #619 from scratchcpp/stop_loading_api

Add API for stopping project loading

Author: adazem009

include/scratchcpp/project.h

@@ -29,6 +29,7 @@ class LIBSCRATCHCPP_EXPORT Project
         Project(const Project &) = delete;
 
         bool load();
+        void stopLoading();
 
         void start();
         void run();

src/internal/projectdownloader.cpp

@@ -17,14 +17,11 @@ static const std::string ASSET_PREFIX = "https://assets.scratch.mit.edu/internal
 static const std::string ASSET_SUFFIX = "/get";
 
 #define CHECK_CANCEL()                                                                                                                                                                                 \
-    m_cancelMutex.lock();                                                                                                                                                                              \
     if (m_cancel) {                                                                                                                                                                                    \
         m_downloadedAssetCount = 0;                                                                                                                                                                    \
-        m_cancelMutex.unlock();                                                                                                                                                                        \
         std::cout << "Download aborted!" << std::endl;                                                                                                                                                 \
         return false;                                                                                                                                                                                  \
-    }                                                                                                                                                                                                  \
-    m_cancelMutex.unlock()
+    }
 
 ProjectDownloader::ProjectDownloader(IDownloaderFactory *downloaderFactory) :
     m_downloaderFactory(downloaderFactory)
@@ -38,9 +35,7 @@ ProjectDownloader::ProjectDownloader(IDownloaderFactory *downloaderFactory) :
 
 bool ProjectDownloader::downloadJson(const std::string &projectId)
 {
-    m_cancelMutex.lock();
     m_cancel = false;
-    m_cancelMutex.unlock();
 
     // Get project token
     std::cout << "Fetching project info of " << projectId << std::endl;
@@ -89,9 +84,7 @@ bool ProjectDownloader::downloadJson(const std::string &projectId)
 
 bool ProjectDownloader::downloadAssets(const std::vector<std::string> &assetIds)
 {
-    m_cancelMutex.lock();
     m_cancel = false;
-    m_cancelMutex.unlock();
 
     auto count = assetIds.size();
     // unsigned int threadCount = std::thread::hardware_concurrency();
@@ -119,20 +112,14 @@ bool ProjectDownloader::downloadAssets(const std::vector<std::string> &assetIds)
 
     // Download assets
     auto f = [this, count](std::shared_ptr<IDownloader> downloader, int index, const std::string &id) {
-        m_cancelMutex.lock();
-
         if (m_cancel)
             return;
 
-        m_cancelMutex.unlock();
-
         bool ret = downloader->download(ASSET_PREFIX + id + ASSET_SUFFIX);
 
         if (!ret) {
             std::cerr << "Failed to download asset: " << id << std::endl;
-            m_cancelMutex.lock();
             m_cancel = true;
-            m_cancelMutex.unlock();
             return;
         }
 
@@ -178,7 +165,7 @@ bool ProjectDownloader::downloadAssets(const std::vector<std::string> &assetIds)
 
         m_assetsMutex.lock();
 
-        if (m_downloadedAssetCount != lastCount) {
+        if (m_downloadedAssetCount != lastCount && !m_cancel) {
             std::cout << "Downloaded assets: " << m_downloadedAssetCount << " of " << count << std::endl;
             lastCount = m_downloadedAssetCount;
         }
@@ -197,7 +184,7 @@ bool ProjectDownloader::downloadAssets(const std::vector<std::string> &assetIds)
             threads.erase(index);
         }
 
-        if (done) {
+        if (done || m_cancel) {
             for (auto &[index, info] : threads)
                 info.first.join();
 
@@ -212,9 +199,7 @@ bool ProjectDownloader::downloadAssets(const std::vector<std::string> &assetIds)
 
 void ProjectDownloader::cancel()
 {
-    m_cancelMutex.lock();
     m_cancel = true;
-    m_cancelMutex.unlock();
     m_downloadedAssetCount = 0;
 }
 

src/internal/projectdownloader.h

@@ -36,8 +36,7 @@ class ProjectDownloader : public IProjectDownloader
         std::vector<std::string> m_assets;
         std::mutex m_assetsMutex;
         std::atomic<unsigned int> m_downloadedAssetCount = 0;
-        bool m_cancel = false;
-        std::mutex m_cancelMutex;
+        std::atomic<bool> m_cancel = false;
         sigslot::signal<unsigned int, unsigned int> m_downloadProgressChanged;
 };
 

src/project.cpp

@@ -1,8 +1,10 @@
 // SPDX-License-Identifier: Apache-2.0
 
 #include <scratchcpp/project.h>
+#include <iostream>
 
 #include "project_p.h"
+#include "internal/projectdownloader.h"
 
 using namespace libscratchcpp;
 
@@ -27,6 +29,14 @@ bool Project::load()
     return impl->load();
 }
 
+/*! Cancels project loading if loading in another thread. */
+void Project::stopLoading()
+{
+    std::cout << "Aborting project loading..." << std::endl;
+    impl->stopLoading = true;
+    impl->downloader->cancel();
+}
+
 /*!
  * Calls all "when green flag clicked" blocks.
  * \note Nothing will happen until run() or frame() is called.

src/project_p.cpp

@@ -47,6 +47,8 @@ bool ProjectPrivate::load()
 
 bool ProjectPrivate::tryLoad(IProjectReader *reader)
 {
+    stopLoading = false;
+
     // Load from URL
     ProjectUrl url(fileName);
 
@@ -57,8 +59,18 @@ bool ProjectPrivate::tryLoad(IProjectReader *reader)
             return false;
         }
 
+        if (stopLoading) {
+            loadingAborted();
+            return false;
+        }
+
         bool ret = reader->loadData(downloader->json());
 
+        if (stopLoading) {
+            loadingAborted();
+            return false;
+        }
+
         if (!ret)
             return false;
 
@@ -91,7 +103,14 @@ bool ProjectPrivate::tryLoad(IProjectReader *reader)
         }
 
         // Download assets
-        if (!downloader->downloadAssets(assetNames)) {
+        ret = downloader->downloadAssets(assetNames);
+
+        if (stopLoading) {
+            loadingAborted();
+            return false;
+        }
+
+        if (!ret) {
             std::cerr << "Failed to download the project assets." << std::endl;
             return false;
         }
@@ -113,7 +132,18 @@ bool ProjectPrivate::tryLoad(IProjectReader *reader)
             return false;
         }
 
+        if (stopLoading) {
+            loadingAborted();
+            return false;
+        }
+
         bool ret = reader->load();
+
+        if (stopLoading) {
+            loadingAborted();
+            return false;
+        }
+
         if (!ret)
             return false;
     }
@@ -125,9 +155,20 @@ bool ProjectPrivate::tryLoad(IProjectReader *reader)
     engine->setExtensions(reader->extensions());
     engine->setUserAgent(reader->userAgent());
     engine->compile();
+
+    if (stopLoading) {
+        loadingAborted();
+        return false;
+    }
+
     return true;
 }
 
+void ProjectPrivate::loadingAborted()
+{
+    std::cout << "Loading aborted." << std::endl;
+}
+
 void ProjectPrivate::start()
 {
     engine->start();

src/project_p.h

@@ -21,6 +21,7 @@ struct ProjectPrivate
 
         bool load();
         bool tryLoad(IProjectReader *reader);
+        void loadingAborted();
 
         void start();
         void run();
@@ -29,6 +30,7 @@ struct ProjectPrivate
         sigslot::signal<unsigned int, unsigned int> &downloadProgressChanged();
 
         std::string fileName;
+        std::atomic<bool> stopLoading = false;
         std::shared_ptr<IEngine> engine = nullptr;
 
         static IProjectDownloaderFactory *downloaderFactory;

test/project/project_test.cpp

@@ -115,3 +115,17 @@ TEST(LoadProjectTest, DownloadProgressChanged)
     EXPECT_CALL(*downloader, downloadProgressChanged).WillOnce(ReturnRef(signal));
     ASSERT_EQ(&p.downloadProgressChanged(), &signal);
 }
+
+TEST(LoadProjectTest, AbortDownload)
+{
+    ProjectDownloaderFactoryMock factory;
+    auto downloader = std::make_shared<ProjectDownloaderMock>();
+    ProjectPrivate::downloaderFactory = &factory;
+
+    EXPECT_CALL(factory, create()).WillOnce(Return(downloader));
+    Project p;
+    ProjectPrivate::downloaderFactory = nullptr;
+
+    EXPECT_CALL(*downloader, cancel());
+    p.stopLoading();
+}