File indexing completed on 2024-05-19 04:42:33

 /*
     SPDX-FileCopyrightText: 2014-2015 Daniel Vrátil <dvratil@redhat.com>
     SPDX-FileCopyrightText: 2015-2019 Daniel Vrátil <dvratil@kde.org>
     SPDX-FileCopyrightText: 2016 Christian Mollekopf <mollekopf@kolabsystems.com>
 
     SPDX-License-Identifier: LGPL-2.0-or-later
 */
 
 #ifndef KASYNC_EXECUTOR_P_H
 #define KASYNC_EXECUTOR_P_H
 
 #include "execution_p.h"
 #include "continuations_p.h"
 #include "debug.h"
 
 namespace KAsync {
 
 template<typename T>
 class Future;
 
 template<typename T>
 class FutureWatcher;
 
 template<typename Out, typename ... In>
 class ContinuationHolder;
 
 template<typename Out, typename ... In>
 class Job;
 
 class Tracer;
 
 namespace Private {
 
 class ExecutorBase;
 using ExecutorBasePtr = QSharedPointer<ExecutorBase>;
 
 class ExecutorBase
 {
     template<typename Out, typename ... In>
     friend class Executor;
 
     template<typename Out, typename ... In>
     friend class KAsync::Job;
 
     friend struct Execution;
     friend class KAsync::Tracer;
 
 public:
     virtual ~ExecutorBase() = default;
 
     virtual ExecutionPtr exec(const ExecutorBasePtr &self, QSharedPointer<Private::ExecutionContext> context) = 0;
 
 protected:
     ExecutorBase(const ExecutorBasePtr &parent)
         : mPrev(parent)
     {}
 
     template<typename T>
     KAsync::Future<T>* createFuture(const ExecutionPtr &execution) const
     {
         return new KAsync::Future<T>(execution);
     }
 
     void prepend(const ExecutorBasePtr &e)
     {
         if (mPrev) {
             mPrev->prepend(e);
         } else {
             mPrev = e;
         }
     }
 
     void addToContext(const QVariant &entry)
     {
         mContext.push_back(entry);
     }
 
     void guard(const QObject *o)
     {
         mGuards.push_back(QPointer<const QObject>{o});
     }
 
     QString mExecutorName;
     QVector<QVariant> mContext;
     QVector<QPointer<const QObject>> mGuards;
     ExecutorBasePtr mPrev;
 };
 
 template<typename Out, typename ... In>
 class Executor : public ExecutorBase
 {
     using PrevOut = std::tuple_element_t<0, std::tuple<In ..., void>>;
 
 public:
     explicit Executor(ContinuationHolder<Out, In ...> &&workerHelper, const ExecutorBasePtr &parent = {},
                       ExecutionFlag executionFlag = ExecutionFlag::GoodCase)
         : ExecutorBase(parent)
         , mContinuationHolder(std::move(workerHelper))
         , executionFlag(executionFlag)
     {
         STORE_EXECUTOR_NAME("Executor", Out, In ...);
     }
 
     virtual ~Executor() = default;
 
     void run(const ExecutionPtr &execution)
     {
         KAsync::Future<PrevOut> *prevFuture = nullptr;
         if (execution->prevExecution) {
             prevFuture = execution->prevExecution->result<PrevOut>();
             assert(prevFuture->isFinished());
         }
 
         //Execute one of the available workers
         KAsync::Future<Out> *future = execution->result<Out>();
 
         const auto &continuation = Executor<Out, In ...>::mContinuationHolder;
         if (continuationIs<AsyncContinuation<Out, In ...>>(continuation)) {
             continuationGet<AsyncContinuation<Out, In ...>>(continuation)(prevFuture ? prevFuture->value() : In() ..., *future);
         } else if (continuationIs<AsyncErrorContinuation<Out, In ...>>(continuation)) {
             continuationGet<AsyncErrorContinuation<Out, In ...>>(continuation)(
                     prevFuture->hasError() ? prevFuture->errors().first() : Error(),
                     prevFuture ? prevFuture->value() : In() ..., *future);
         } else if (continuationIs<SyncContinuation<Out, In ...>>(continuation)) {
             callAndApply(prevFuture ? prevFuture->value() : In() ...,
                          continuationGet<SyncContinuation<Out, In ...>>(continuation), *future, std::is_void<Out>());
             future->setFinished();
         } else if (continuationIs<SyncErrorContinuation<Out, In ...>>(continuation)) {
             assert(prevFuture);
             callAndApply(prevFuture->hasError() ? prevFuture->errors().first() : Error(),
                          prevFuture ? prevFuture->value() : In() ...,
                          continuationGet<SyncErrorContinuation<Out, In ...>>(continuation), *future, std::is_void<Out>());
             future->setFinished();
         } else if (continuationIs<JobContinuation<Out, In ...>>(continuation)) {
             executeJobAndApply(prevFuture ? prevFuture->value() : In() ...,
                                continuationGet<JobContinuation<Out, In ...>>(continuation), *future, std::is_void<Out>());
         } else if (continuationIs<JobErrorContinuation<Out, In ...>>(continuation)) {
             executeJobAndApply(prevFuture->hasError() ? prevFuture->errors().first() : Error(),
                                prevFuture ? prevFuture->value() : In() ...,
                                continuationGet<JobErrorContinuation<Out, In ...>>(continuation), *future, std::is_void<Out>());
         }
 
     }
 
     ExecutionPtr exec(const ExecutorBasePtr &self, QSharedPointer<Private::ExecutionContext> context) override
     {
         /*
          * One executor per job, created with the construction of the Job object.
          * One execution per job per exec(), created only once exec() is called.
          *
          * The executors make up the linked list that makes up the complete execution chain.
          *
          * The execution then tracks the execution of each executor.
          */
 
         // Passing 'self' to execution ensures that the Executor chain remains
         // valid until the entire execution is finished
         ExecutionPtr execution = ExecutionPtr::create(self);
 #ifndef QT_NO_DEBUG
         execution->tracer = std::make_unique<Tracer>(execution.data()); // owned by execution
 #endif
 
         context->guards += mGuards;
 
         // chainup
         execution->prevExecution = mPrev ? mPrev->exec(mPrev, context) : ExecutionPtr();
 
         execution->resultBase = ExecutorBase::createFuture<Out>(execution);
         //We watch our own future to finish the execution once we're done
         auto fw = new KAsync::FutureWatcher<Out>();
         QObject::connect(fw, &KAsync::FutureWatcher<Out>::futureReady,
                          [fw, execution]() {
                              execution->setFinished();
                              delete fw;
                          });
         fw->setFuture(*execution->result<Out>());
 
         KAsync::Future<PrevOut> *prevFuture = execution->prevExecution ? execution->prevExecution->result<PrevOut>()
                                                                        : nullptr;
         if (!prevFuture || prevFuture->isFinished()) { //The previous job is already done
             runExecution(prevFuture, execution, context->guardIsBroken());
         } else { //The previous job is still running and we have to wait for it's completion
             auto prevFutureWatcher = new KAsync::FutureWatcher<PrevOut>();
             QObject::connect(prevFutureWatcher, &KAsync::FutureWatcher<PrevOut>::futureReady,
                              [prevFutureWatcher, execution, this, context]() {
                                  auto prevFuture = prevFutureWatcher->future();
                                  assert(prevFuture.isFinished());
                                  delete prevFutureWatcher;
                                  runExecution(&prevFuture, execution, context->guardIsBroken());
                              });
 
             prevFutureWatcher->setFuture(*static_cast<KAsync::Future<PrevOut>*>(prevFuture));
         }
 
         return execution;
     }
 
 private:
     void runExecution(const KAsync::Future<PrevOut> *prevFuture, const ExecutionPtr &execution, bool guardIsBroken)
     {
         if (guardIsBroken) {
             execution->resultBase->setFinished();
             return;
         }
         if (prevFuture) {
             if (prevFuture->hasError() && executionFlag == ExecutionFlag::GoodCase) {
                 //Propagate the error to the outer Future
                 Q_ASSERT(prevFuture->errors().size() == 1);
                 execution->resultBase->setError(prevFuture->errors().first());
                 return;
             }
             if (!prevFuture->hasError() && executionFlag == ExecutionFlag::ErrorCase) {
                 //Propagate the value to the outer Future
                 copyFutureValue<PrevOut>(*prevFuture, *execution->result<PrevOut>());
                 execution->resultBase->setFinished();
                 return;
             }
         }
         run(execution);
     }
 
     void executeJobAndApply(In && ... input, const JobContinuation<Out, In ...> &func,
                             Future<Out> &future, std::false_type)
     {
         func(std::forward<In>(input) ...)
             .template then<void, Out>([&future](const KAsync::Error &error, const Out &v,
                                                 KAsync::Future<void> &f) {
                 if (error) {
                     future.setError(error);
                 } else {
                     future.setResult(v);
                 }
                 f.setFinished();
             }).exec();
     }
 
     void executeJobAndApply(In && ... input, const JobContinuation<Out, In ...> &func,
                             Future<Out> &future, std::true_type)
     {
         func(std::forward<In>(input) ...)
             .template then<void>([&future](const KAsync::Error &error, KAsync::Future<void> &f) {
                 if (error) {
                     future.setError(error);
                 } else {
                     future.setFinished();
                 }
                 f.setFinished();
             }).exec();
     }
 
     void executeJobAndApply(const Error &error, In && ... input, const JobErrorContinuation<Out, In ...> &func,
                             Future<Out> &future, std::false_type)
     {
         func(error, std::forward<In>(input) ...)
             .template then<void, Out>([&future](const KAsync::Error &error, const Out &v,
                                                 KAsync::Future<void> &f) {
                 if (error) {
                     future.setError(error);
                 } else {
                     future.setResult(v);
                 }
                 f.setFinished();
             }).exec();
     }
 
     void executeJobAndApply(const Error &error, In && ... input, const JobErrorContinuation<Out, In ...> &func,
                             Future<Out> &future, std::true_type)
     {
         func(error, std::forward<In>(input) ...)
             .template then<void>([&future](const KAsync::Error &error, KAsync::Future<void> &f) {
                 if (error) {
                     future.setError(error);
                 } else {
                     future.setFinished();
                 }
                 f.setFinished();
             }).exec();
     }
 
     void callAndApply(In && ... input, const SyncContinuation<Out, In ...> &func, Future<Out> &future, std::false_type)
     {
         future.setValue(func(std::forward<In>(input) ...));
     }
 
     void callAndApply(In && ... input, const SyncContinuation<Out, In ...> &func, Future<Out> &, std::true_type)
     {
         func(std::forward<In>(input) ...);
     }
 
     void callAndApply(const Error &error, In && ... input, const SyncErrorContinuation<Out, In ...> &func, Future<Out> &future, std::false_type)
     {
         future.setValue(func(error, std::forward<In>(input) ...));
     }
 
     void callAndApply(const Error &error, In && ... input, const SyncErrorContinuation<Out, In ...> &func, Future<Out> &, std::true_type)
     {
         func(error, std::forward<In>(input) ...);
     }
 
     template<typename T>
     std::enable_if_t<!std::is_void<T>::value>
     copyFutureValue(const KAsync::Future<T> &in, KAsync::Future<T> &out)
     {
         out.setValue(in.value());
     }
 
     template<typename T>
     std::enable_if_t<std::is_void<T>::value>
     copyFutureValue(const KAsync::Future<T> &, KAsync::Future<T> &)
     {
         //noop
     }
 private:
     ContinuationHolder<Out, In ...> mContinuationHolder;
     const ExecutionFlag executionFlag;
 };
 
 } // namespace Private
 } // nameapce KAsync
 
 #endif