Moved resultprovider to separate file.

1 files changed, 221 insertions, 0 deletions

diff --git a/common/resultprovider.h b/common/resultprovider.h
new file mode 100644
index 0000000..4d985d9
--- /dev/null
+++ b/common/resultprovider.h
@@ -0,0 +1,221 @@
+/*
+ * Copyright (C) 2014 Christian Mollekopf <chrigi_1@fastmail.fm>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) version 3, or any
+ * later version accepted by the membership of KDE e.V. (or its
+ * successor approved by the membership of KDE e.V.), which shall
+ * act as a proxy defined in Section 6 of version 3 of the license.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+#include <functional>
+#include <memory>
+#include "threadboundary.h"
+
+namespace async {
+
+/**
+* Query result set
+*/
+template<class T>
+class ResultEmitter;
+
+/*
+* The promise side for the result emitter
+*/
+template<class T>
+class ResultProvider {
+private:
+    void callInMainThreadOnEmitter(void (ResultEmitter<T>::*f)())
+    {
+        //We use the eventloop to call the addHandler directly from the main eventloop.
+        //That way the result emitter implementation doesn't have to care about threadsafety at all.
+        //The alternative would be to make all handlers of the emitter threadsafe.
+        if (auto emitter = mResultEmitter.toStrongRef()) {
+            auto weakEmitter = mResultEmitter;
+            //We don't want to keep the emitter alive here, so we only capture a weak reference
+            emitter->mThreadBoundary.callInMainThread([weakEmitter, f]() {
+                if (auto strongRef = weakEmitter.toStrongRef()) {
+                    (strongRef.data()->*f)();
+                }
+            });
+        }
+    }
+
+    void callInMainThreadOnEmitter(const std::function<void()> &f)
+    {
+        //We use the eventloop to call the addHandler directly from the main eventloop.
+        //That way the result emitter implementation doesn't have to care about threadsafety at all.
+        //The alternative would be to make all handlers of the emitter threadsafe.
+        if (auto emitter = mResultEmitter.toStrongRef()) {
+            emitter->mThreadBoundary.callInMainThread([f]() {
+                f();
+            });
+        }
+    }
+
+public:
+    //Called from worker thread
+    void add(const T &value)
+    {
+        //Because I don't know how to use bind
+        auto weakEmitter = mResultEmitter;
+        callInMainThreadOnEmitter([weakEmitter, value](){
+            if (auto strongRef = weakEmitter.toStrongRef()) {
+                strongRef->addHandler(value);
+            }
+        });
+    }
+
+    void initialResultSetComplete()
+    {
+        callInMainThreadOnEmitter(&ResultEmitter<T>::initialResultSetComplete);
+    }
+
+    //Called from worker thread
+    void complete()
+    {
+        callInMainThreadOnEmitter(&ResultEmitter<T>::complete);
+    }
+
+    void clear()
+    {
+        callInMainThreadOnEmitter(&ResultEmitter<T>::clear);
+    }
+
+
+    QSharedPointer<ResultEmitter<T> > emitter()
+    {
+        if (!mResultEmitter) {
+            //We have to go over a separate var and return that, otherwise we'd delete the emitter immediately again
+            auto sharedPtr = QSharedPointer<ResultEmitter<T> >(new ResultEmitter<T>, [this](ResultEmitter<T> *emitter){ done(); delete emitter; });
+            mResultEmitter = sharedPtr;
+            return sharedPtr;
+        }
+
+        return mResultEmitter.toStrongRef();
+    }
+
+    /**
+        * For lifetimemanagement only.
+        * We keep the runner alive as long as the result provider exists.
+        */
+    void setQueryRunner(const QSharedPointer<QObject> &runner)
+    {
+        mQueryRunner = runner;
+    }
+
+    /**
+        * For lifetimemanagement only.
+        * We keep the runner alive as long as the result provider exists.
+        */
+    void setFacade(const std::shared_ptr<void> &facade)
+    {
+        mFacade = facade;
+    }
+
+    void onDone(const std::function<void()> &callback)
+    {
+        mOnDoneCallback = callback;
+    }
+
+    bool isDone() const
+    {
+        //The existance of the emitter currently defines wether we're done or not.
+        return mResultEmitter.toStrongRef().isNull();
+    }
+
+private:
+    void done()
+    {
+        qWarning() << "done";
+        if (mOnDoneCallback) {
+            mOnDoneCallback();
+            mOnDoneCallback = std::function<void()>();
+        }
+    }
+
+    QWeakPointer<ResultEmitter<T> > mResultEmitter;
+    QSharedPointer<QObject> mQueryRunner;
+    std::shared_ptr<void> mFacade;
+    std::function<void()> mOnDoneCallback;
+};
+
+/*
+* The future side for the client.
+*
+* It does not directly hold the state.
+*
+* The advantage of this is that we can specialize it to:
+* * do inline transformations to the data
+* * directly store the state in a suitable datastructure: QList, QSet, std::list, QVector, ...
+* * build async interfaces with signals
+* * build sync interfaces that block when accessing the value
+*
+*/
+template<class DomainType>
+class ResultEmitter {
+public:
+    void onAdded(const std::function<void(const DomainType&)> &handler)
+    {
+        addHandler = handler;
+    }
+    // void onRemoved(const std::function<void(const T&)> &handler);
+    void onInitialResultSetComplete(const std::function<void(void)> &handler)
+    {
+        initialResultSetCompleteHandler = handler;
+    }
+    void onComplete(const std::function<void(void)> &handler)
+    {
+        completeHandler = handler;
+    }
+    void onClear(const std::function<void(void)> &handler)
+    {
+        clearHandler = handler;
+    }
+
+    void add(const DomainType &value)
+    {
+        addHandler(value);
+    }
+
+    void initialResultSetComplete()
+    {
+        initialResultSetCompleteHandler();
+    }
+
+    void complete()
+    {
+        completeHandler();
+    }
+
+    void clear()
+    {
+        clearHandler();
+    }
+
+private:
+    friend class ResultProvider<DomainType>;
+
+    std::function<void(const DomainType&)> addHandler;
+    // std::function<void(const T&)> removeHandler;
+    std::function<void(void)> initialResultSetCompleteHandler;
+    std::function<void(void)> completeHandler;
+    std::function<void(void)> clearHandler;
+    ThreadBoundary mThreadBoundary;
+};
+
+}
+