FS|libcore: Clarified waiting behavior when populating file system

skyjake · Oct 23, 2017 · bde41ea · bde41ea
1 parent 075471b
commit bde41ea
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Showing 6 changed files with 57 additions and 23 deletions.
diff --git a/doomsday/sdk/libcore/include/de/filesys/filesystem.h b/doomsday/sdk/libcore/include/de/filesys/filesystem.h
@@ -145,9 +145,10 @@ class DENG2_PUBLIC FileSystem : public System
     Folder const &root() const;
 
     /**
-     * Refresh the file system. Populates all folders with files from the feeds.
+     * Refresh the file system asynchronously. Populates all folders with files from
+     * the feeds.
      */
-    void refresh();
+    void refreshAsync();
 
     enum FolderCreationBehavior {
         DontInheritFeeds   = 0,     ///< Subfolder will not have any feeds created for them.

diff --git a/doomsday/sdk/libcore/include/de/filesys/folder.h b/doomsday/sdk/libcore/include/de/filesys/folder.h
@@ -28,6 +28,7 @@
 
 namespace de {
 
+struct AsyncTask;
 class Feed;
 
 /**
@@ -360,7 +361,23 @@ class DENG2_PUBLIC Folder : public File
     Node const *tryGetChild(String const &name) const;
 
 public:
-    static void waitForPopulation();
+    enum WaitBehavior {
+        OnlyInBackground,
+        BlockingMainThread,
+    };
+    static void waitForPopulation(WaitBehavior waitBehavior = OnlyInBackground);
+
+    /**
+     * When all folder population tasks are finished, performs a callback in the main
+     * thread. Does not block the main thread. If nothing is currently being populated,
+     * the callback is called immediately before the method returns.
+     *
+     * @param func  Callback to be called in the main thread.
+     *
+     * @return Task handle. Can be ignored or added to an AsyncScope.
+     */
+    static AsyncTask *afterPopulation(std::function<void ()> func);
+
     static bool isPopulatingAsync();
 
 private:

diff --git a/doomsday/sdk/libcore/src/core/app.cpp b/doomsday/sdk/libcore/src/core/app.cpp
@@ -268,9 +268,8 @@ DENG2_PIMPL(App)
         // Metadata for files.
         metaBank.reset(new MetadataBank);
 
-        // Populate the file system.
-        fs.refresh();
-        Folder::waitForPopulation();
+        // Populate the file system (blocking).
+        fs.root().populate(Folder::PopulateFullTree);
 
         // Ensure known subfolders exist:
         // - /home/configs is used by de::Profiles.

diff --git a/doomsday/sdk/libcore/src/data/bank.cpp b/doomsday/sdk/libcore/src/data/bank.cpp
@@ -572,7 +572,7 @@ DENG2_PIMPL(Bank)
 
         if (Folder *folder = serialCache->folder())
         {
-            Folder::waitForPopulation();
+            Folder::waitForPopulation(Folder::BlockingMainThread);
             folder->destroyAllFilesRecursively();
         }
     }

diff --git a/doomsday/sdk/libcore/src/filesys/filesystem.cpp b/doomsday/sdk/libcore/src/filesys/filesystem.cpp
@@ -87,23 +87,14 @@ void FileSystem::addInterpreter(filesys::IInterpreter const &interpreter)
     d->interpreters.prepend(&interpreter);
 }
 
-void FileSystem::refresh()
+void FileSystem::refreshAsync()
 {
-    if (Folder::isPopulatingAsync())
+    // We may need to wait until a previous population is complete.
+    Folder::afterPopulation([this] ()
     {
-        qDebug() << "FileSystem has to wait for previous population to finish...";
-    }
-
-    // Wait for a previous refresh to finish.
-    Folder::waitForPopulation();
-
-    LOG_AS("FS::refresh");
-
-    //Time startedAt;
-    d->root->populate(Folder::PopulateAsyncFullTree);
-
-    /*LOGDEV_RES_VERBOSE("Completed in %.2f seconds") << startedAt.since();
-    printIndex();*/
+        LOG_AS("FS::refresh");
+        d->root->populate(Folder::PopulateAsyncFullTree);
+    });
 }
 
 Folder &FileSystem::makeFolder(String const &path, FolderCreationBehaviors behavior)

diff --git a/doomsday/sdk/libcore/src/filesys/folder.cpp b/doomsday/sdk/libcore/src/filesys/folder.cpp
@@ -19,6 +19,8 @@
 
 #include "de/Folder"
 
+#include "de/App"
+#include "de/Async"
 #include "de/DirectoryFeed"
 #include "de/FS"
 #include "de/Feed"
@@ -507,11 +509,35 @@ filesys::Node const *Folder::tryGetChild(String const &name) const
     return nullptr;
 }
 
-void Folder::waitForPopulation()
+void Folder::waitForPopulation(WaitBehavior waitBehavior)
 {
+    if (waitBehavior == OnlyInBackground && App::inMainThread())
+    {
+        DENG2_ASSERT(!App::inMainThread());
+        throw Error("Folder::waitForPopulation", "Not allowed to block the main thread");
+    }
     internal::populateTasks.waitForDone();
 }
 
+AsyncTask *Folder::afterPopulation(std::function<void ()> func)
+{
+    if (!isPopulatingAsync())
+    {
+        func();
+        return nullptr;
+    }
+
+    return async([] ()
+    {
+        waitForPopulation();
+        return 0;
+    },
+    [func] (int)
+    {
+        func();
+    });
+}
+
 bool Folder::isPopulatingAsync()
 {
     return !internal::populateTasks.isDone();