Add scheduleWithContext to event dispatcher

src/lib/fcitx-utils/eventdispatcher.h

@@ -11,6 +11,7 @@
 #include <functional>
 #include <memory>
 #include <fcitx-utils/macros.h>
+#include <fcitx-utils/trackableobject.h>
 #include "fcitxutils_export.h"
 
 namespace fcitx {
@@ -43,6 +44,7 @@ class FCITXUTILS_EXPORT EventDispatcher {
      * thread from event loop.
      */
     void detach();
+
     /**
      * A thread-safe function to schedule a functor to be call from event loop.
      *
@@ -54,6 +56,33 @@ class FCITXUTILS_EXPORT EventDispatcher {
      */
     void schedule(std::function<void()> functor);
 
+    /**
+     * A helper function that allows to only invoke certain function if the
+     * reference is still valid.
+     *
+     * If context object is not valid when calling scheduleWithContext, it won't
+     * be scheduled at all.
+     *
+     * @param context the context object.
+     * @param functor function to be scheduled
+     *
+     * @since 5.1.8
+     */
+    template <typename T>
+    void scheduleWithContext(TrackableObjectReference<T> context,
+                             std::function<void()> functor) {
+        if (!context.isValid()) {
+            return;
+        }
+
+        schedule(
+            [context = std::move(context), functor = std::move(functor)]() {
+                if (context.isValid()) {
+                    functor();
+                }
+            });
+    }
+
     /**
      * Return the currently attached event loop
      *

test/testeventdispatcher.cpp

@@ -7,9 +7,11 @@
 #include <unistd.h>
 #include <atomic>
 #include <thread>
+#include <vector>
 #include "fcitx-utils/event.h"
 #include "fcitx-utils/eventdispatcher.h"
 #include "fcitx-utils/log.h"
+#include "fcitx-utils/trackableobject.h"
 
 using namespace fcitx;
 
@@ -38,6 +40,22 @@ void basicTest() {
     thread.join();
 }
 
+void testOrder() {
+    EventLoop loop;
+    EventDispatcher dispatcher;
+    dispatcher.attach(&loop);
+    std::vector<int> value;
+    for (int i = 0; i < 100; i++) {
+        dispatcher.schedule([i, &value]() { value.push_back(i); });
+    }
+    dispatcher.schedule([&loop]() { loop.exit(); });
+    loop.exec();
+    FCITX_ASSERT(value.size() == 100);
+    for (int i = 0; i < 100; i++) {
+        FCITX_ASSERT(i == value[i]) << i << " " << value[i];
+    }
+}
+
 void recursiveSchedule() {
     EventDispatcher dispatcher;
     EventLoop loop;
@@ -59,8 +77,35 @@ void recursiveSchedule() {
     FCITX_ASSERT(counter == 100);
 }
 
+class TestObject : public TrackableObject<TestObject> {};
+
+void withContext() {
+    EventDispatcher dispatcher;
+    EventLoop loop;
+    dispatcher.attach(&loop);
+    bool called = false;
+    bool invalidCalled = false;
+    TestObject validObject;
+    {
+        TestObject invalidObject;
+        dispatcher.scheduleWithContext(validObject.watch(),
+                                       [&called]() { called = true; });
+        dispatcher.scheduleWithContext(
+            invalidObject.watch(),
+            [&invalidCalled]() { invalidCalled = true; });
+    }
+
+    dispatcher.schedule([&loop]() { loop.exit(); });
+    loop.exec();
+
+    FCITX_ASSERT(called);
+    FCITX_ASSERT(!invalidCalled);
+}
+
 int main() {
     basicTest();
+    testOrder();
     recursiveSchedule();
+    withContext();
     return 0;
 }