Merge pull request #14440 from alalek:async_array

modules/core/include/opencv2/core.hpp

@@ -68,6 +68,7 @@
         @defgroup core_c_glue Connections with C++
     @}
     @defgroup core_array Operations on arrays
+    @defgroup core_async Asynchronous API
     @defgroup core_xml XML/YAML Persistence
     @defgroup core_cluster Clustering
     @defgroup core_utils Utility and system functions and macros

modules/core/include/opencv2/core/async.hpp

@@ -0,0 +1,105 @@
+// This file is part of OpenCV project.
+// It is subject to the license terms in the LICENSE file found in the top-level directory
+// of this distribution and at http://opencv.org/license.html.
+
+#ifndef OPENCV_CORE_ASYNC_HPP
+#define OPENCV_CORE_ASYNC_HPP
+
+#include <opencv2/core/mat.hpp>
+
+#ifdef CV_CXX11
+//#include <future>
+#include <chrono>
+#endif
+
+namespace cv {
+
+/** @addtogroup core_async
+
+@{
+*/
+
+
+/** @brief Returns result of asynchronous operations
+
+Object has attached asynchronous state.
+Assignment operator doesn't clone asynchronous state (it is shared between all instances).
+
+Result can be fetched via get() method only once.
+
+*/
+class CV_EXPORTS_W AsyncArray
+{
+public:
+    ~AsyncArray() CV_NOEXCEPT;
+    CV_WRAP AsyncArray() CV_NOEXCEPT;
+    AsyncArray(const AsyncArray& o) CV_NOEXCEPT;
+    AsyncArray& operator=(const AsyncArray& o) CV_NOEXCEPT;
+    CV_WRAP void release() CV_NOEXCEPT;
+
+    /** Fetch the result.
+    @param[out] dst destination array
+
+    Waits for result until container has valid result.
+    Throws exception if exception was stored as a result.
+
+    Throws exception on invalid container state.
+
+    @note Result or stored exception can be fetched only once.
+    */
+    CV_WRAP void get(OutputArray dst) const;
+
+    /** Retrieving the result with timeout
+    @param[out] dst destination array
+    @param[in] timeoutNs timeout in nanoseconds, -1 for infinite wait
+
+    @returns true if result is ready, false if the timeout has expired
+
+    @note Result or stored exception can be fetched only once.
+    */
+    bool get(OutputArray dst, int64 timeoutNs) const;
+
+    CV_WRAP inline
+    bool get(OutputArray dst, double timeoutNs) const { return get(dst, (int64)timeoutNs); }
+
+    bool wait_for(int64 timeoutNs) const;
+
+    CV_WRAP inline
+    bool wait_for(double timeoutNs) const { return wait_for((int64)timeoutNs); }
+
+    CV_WRAP bool valid() const CV_NOEXCEPT;
+
+#ifdef CV_CXX11
+    inline AsyncArray(AsyncArray&& o) { p = o.p; o.p = NULL; }
+    inline AsyncArray& operator=(AsyncArray&& o) CV_NOEXCEPT { std::swap(p, o.p); return *this; }
+
+    template<typename _Rep, typename _Period>
+    inline bool get(OutputArray dst, const std::chrono::duration<_Rep, _Period>& timeout)
+    {
+        return get(dst, (int64)(std::chrono::nanoseconds(timeout).count()));
+    }
+
+    template<typename _Rep, typename _Period>
+    inline bool wait_for(const std::chrono::duration<_Rep, _Period>& timeout)
+    {
+        return wait_for((int64)(std::chrono::nanoseconds(timeout).count()));
+    }
+
+#if 0
+    std::future<Mat> getFutureMat() const;
+    std::future<UMat> getFutureUMat() const;
+#endif
+#endif
+
+
+    // PImpl
+    struct Impl; friend struct Impl;
+    inline void* _getImpl() const CV_NOEXCEPT { return p; }
+protected:
+    Impl* p;
+};
+
+
+//! @}
+} // namespace
+#endif // OPENCV_CORE_ASYNC_HPP

modules/core/include/opencv2/core/bindings_utils.hpp

@@ -5,6 +5,9 @@
 #ifndef OPENCV_CORE_BINDINGS_UTILS_HPP
 #define OPENCV_CORE_BINDINGS_UTILS_HPP
 
+#include <opencv2/core/async.hpp>
+#include <opencv2/core/detail/async_promise.hpp>
+
 namespace cv { namespace utils {
 //! @addtogroup core_utils
 //! @{
@@ -17,6 +20,29 @@ CV_EXPORTS_W String dumpInputOutputArray(InputOutputArray argument);
 
 CV_EXPORTS_W String dumpInputOutputArrayOfArrays(InputOutputArrayOfArrays argument);
 
+CV_WRAP static inline
+AsyncArray testAsyncArray(InputArray argument)
+{
+    AsyncPromise p;
+    p.setValue(argument);
+    return p.getArrayResult();
+}
+
+CV_WRAP static inline
+AsyncArray testAsyncException()
+{
+    AsyncPromise p;
+    try
+    {
+        CV_Error(Error::StsOk, "Test: Generated async error");
+    }
+    catch (const cv::Exception& e)
+    {
+        p.setException(e);
+    }
+    return p.getArrayResult();
+}
+
 //! @}
 }} // namespace
 

modules/core/include/opencv2/core/cvdef.h

@@ -622,6 +622,19 @@ Cv64suf;
 #  define CV_FINAL
 #endif
 
+/****************************************************************************************\
+*                                     C++11 noexcept                                     *
+\****************************************************************************************/
+
+#ifndef CV_NOEXCEPT
+#  ifdef CV_CXX11
+#    define CV_NOEXCEPT noexcept
+#  endif
+#endif
+#ifndef CV_NOEXCEPT
+#  define CV_NOEXCEPT
+#endif
+
 
 
 // Integer types portatibility

modules/core/include/opencv2/core/detail/async_promise.hpp

@@ -0,0 +1,71 @@
+// This file is part of OpenCV project.
+// It is subject to the license terms in the LICENSE file found in the top-level directory
+// of this distribution and at http://opencv.org/license.html.
+
+#ifndef OPENCV_CORE_ASYNC_PROMISE_HPP
+#define OPENCV_CORE_ASYNC_PROMISE_HPP
+
+#include "../async.hpp"
+
+#include "exception_ptr.hpp"
+
+namespace cv {
+
+/** @addtogroup core_async
+@{
+*/
+
+
+/** @brief Provides result of asynchronous operations
+
+*/
+class CV_EXPORTS AsyncPromise
+{
+public:
+    ~AsyncPromise() CV_NOEXCEPT;
+    AsyncPromise() CV_NOEXCEPT;
+    explicit AsyncPromise(const AsyncPromise& o) CV_NOEXCEPT;
+    AsyncPromise& operator=(const AsyncPromise& o) CV_NOEXCEPT;
+    void release() CV_NOEXCEPT;
+
+    /** Returns associated AsyncArray
+    @note Can be called once
+    */
+    AsyncArray getArrayResult();
+
+    /** Stores asynchronous result.
+    @param[in] value result
+    */
+    void setValue(InputArray value);
+
+    // TODO "move" setters
+
+#if CV__EXCEPTION_PTR
+    /** Stores exception.
+    @param[in] exception exception to be raised in AsyncArray
+    */
+    void setException(std::exception_ptr exception);
+#endif
+
+    /** Stores exception.
+    @param[in] exception exception to be raised in AsyncArray
+    */
+    void setException(const cv::Exception& exception);
+
+#ifdef CV_CXX11
+    explicit AsyncPromise(AsyncPromise&& o) { p = o.p; o.p = NULL; }
+    AsyncPromise& operator=(AsyncPromise&& o) CV_NOEXCEPT { std::swap(p, o.p); return *this; }
+#endif
+
+
+    // PImpl
+    typedef struct AsyncArray::Impl Impl; friend struct AsyncArray::Impl;
+    inline void* _getImpl() const CV_NOEXCEPT { return p; }
+protected:
+    Impl* p;
+};
+
+
+//! @}
+} // namespace
+#endif // OPENCV_CORE_ASYNC_PROMISE_HPP

modules/core/include/opencv2/core/detail/exception_ptr.hpp

@@ -0,0 +1,27 @@
+// This file is part of OpenCV project.
+// It is subject to the license terms in the LICENSE file found in the top-level directory
+// of this distribution and at http://opencv.org/license.html.
+
+#ifndef OPENCV_CORE_DETAILS_EXCEPTION_PTR_H
+#define OPENCV_CORE_DETAILS_EXCEPTION_PTR_H
+
+#ifndef CV__EXCEPTION_PTR
+#  if defined(__ANDROID__) && defined(ATOMIC_INT_LOCK_FREE) && ATOMIC_INT_LOCK_FREE < 2
+#    define CV__EXCEPTION_PTR 0  // Not supported, details: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58938
+#  elif defined(CV_CXX11)
+#    define CV__EXCEPTION_PTR 1
+#  elif defined(_MSC_VER)
+#    define CV__EXCEPTION_PTR (_MSC_VER >= 1600)
+#  elif defined(__clang__)
+#    define CV__EXCEPTION_PTR 0  // C++11 only (see above)
+#  elif defined(__GNUC__) && defined(__GXX_EXPERIMENTAL_CXX0X__)
+#    define CV__EXCEPTION_PTR (__GXX_EXPERIMENTAL_CXX0X__ > 0)
+#  endif
+#endif
+#ifndef CV__EXCEPTION_PTR
+#  define CV__EXCEPTION_PTR 0
+#elif CV__EXCEPTION_PTR
+#  include <exception>  // std::exception_ptr
+#endif
+
+#endif // OPENCV_CORE_DETAILS_EXCEPTION_PTR_H

modules/core/include/opencv2/core/mat.hpp

@@ -377,6 +377,9 @@ public:
 
     void assign(const std::vector<UMat>& v) const;
     void assign(const std::vector<Mat>& v) const;
+
+    void move(UMat& u) const;
+    void move(Mat& m) const;
 };
 
 

modules/core/misc/python/pyopencv_async.hpp

@@ -0,0 +1,8 @@
+#ifdef HAVE_OPENCV_CORE
+
+#include "opencv2/core/async.hpp"
+
+CV_PY_TO_CLASS(AsyncArray);
+CV_PY_FROM_CLASS(AsyncArray);
+
+#endif

modules/core/src/async.cpp

@@ -0,0 +1,366 @@
+// This file is part of OpenCV project.
+// It is subject to the license terms in the LICENSE file found in the top-level directory
+// of this distribution and at http://opencv.org/license.html.
+
+#include "precomp.hpp"
+//#undef CV_CXX11  // debug non C++11 mode
+#include "opencv2/core/async.hpp"
+#include "opencv2/core/detail/async_promise.hpp"
+
+#include "opencv2/core/cvstd.hpp"
+
+#include <opencv2/core/utils/logger.defines.hpp>
+#undef CV_LOG_STRIP_LEVEL
+#define CV_LOG_STRIP_LEVEL CV_LOG_LEVEL_DEBUG + 1
+#include <opencv2/core/utils/logger.hpp>
+
+
+#ifdef CV_CXX11
+#include <mutex>
+#include <condition_variable>
+#include <chrono>
+#endif
+
+namespace cv {
+
+/**
+Manages shared state of asynchronous result
+*/
+struct AsyncArray::Impl
+{
+    int refcount;
+    void addrefFuture() CV_NOEXCEPT { CV_XADD(&refcount_future, 1); CV_XADD(&refcount, 1); } \
+    void releaseFuture() CV_NOEXCEPT { CV_XADD(&refcount_future, -1); if(1 == CV_XADD(&refcount, -1)) delete this; } \
+    int refcount_future;
+    void addrefPromise() CV_NOEXCEPT { CV_XADD(&refcount_promise, 1); CV_XADD(&refcount, 1); } \
+    void releasePromise() CV_NOEXCEPT { CV_XADD(&refcount_promise, -1); if(1 == CV_XADD(&refcount, -1)) delete this; } \
+    int refcount_promise;
+
+#ifdef CV_CXX11
+    mutable std::mutex mtx;
+    mutable std::condition_variable cond_var;
+#else
+    mutable cv::Mutex mtx;
+#endif
+
+    mutable bool has_result; // Mat, UMat or exception
+
+    mutable cv::Ptr<Mat> result_mat;
+    mutable cv::Ptr<UMat> result_umat;
+
+
+    bool has_exception;
+#if CV__EXCEPTION_PTR
+    std::exception_ptr exception;
+#endif
+    cv::Exception cv_exception;
+
+    mutable bool result_is_fetched;
+
+    bool future_is_returned;
+
+    Impl()
+        : refcount(1), refcount_future(0), refcount_promise(1)
+        , has_result(false)
+        , has_exception(false)
+        , result_is_fetched(false)
+        , future_is_returned(false)
+    {
+        // nothing
+    }
+
+    ~Impl()
+    {
+        if (has_result && !result_is_fetched)
+        {
+            CV_LOG_INFO(NULL, "Asynchronous result has not been fetched");
+        }
+    }
+
+    bool get(OutputArray dst, int64 timeoutNs) const
+    {
+        CV_Assert(!result_is_fetched);
+        if (!has_result)
+        {
+            if(refcount_promise == 0)
+                CV_Error(Error::StsInternal, "Asynchronous result producer has been destroyed");
+            if (!wait_for(timeoutNs))
+                return false;
+        }
+#ifdef CV_CXX11
+        std::unique_lock<std::mutex> lock(mtx);
+#else
+        cv::AutoLock lock(mtx);
+#endif
+        if (has_result)
+        {
+            if (!result_mat.empty())
+            {
+                dst.move(*result_mat.get());
+                result_mat.release();
+                result_is_fetched = true;
+                return true;
+            }
+            if (!result_umat.empty())
+            {
+                dst.move(*result_umat.get());
+                result_umat.release();
+                result_is_fetched = true;
+                return true;
+            }
+#if CV__EXCEPTION_PTR
+            if (has_exception && exception)
+            {
+                result_is_fetched = true;
+                std::rethrow_exception(exception);
+            }
+#endif
+            if (has_exception)
+            {
+                result_is_fetched = true;
+                throw cv_exception;
+            }
+            CV_Error(Error::StsInternal, "AsyncArray: invalid state of 'has_result = true'");
+        }
+        CV_Assert(!has_result);
+        CV_Assert(timeoutNs < 0);
+        return false;
+    }
+
+    bool valid() const CV_NOEXCEPT
+    {
+        if (result_is_fetched)
+            return false;
+        if (refcount_promise == 0 && !has_result)
+            return false;
+        return true;
+    }
+
+    bool wait_for(int64 timeoutNs) const
+    {
+        CV_Assert(valid());
+        if (has_result)
+            return has_result;
+        if (timeoutNs == 0)
+            return has_result;
+        CV_LOG_INFO(NULL, "Waiting for async result ...");
+#ifdef CV_CXX11
+        std::unique_lock<std::mutex> lock(mtx);
+        const auto cond_pred = [&]{ return has_result == true; };
+        if (timeoutNs > 0)
+            return cond_var.wait_for(lock, std::chrono::nanoseconds(timeoutNs), cond_pred);
+        else
+        {
+            cond_var.wait(lock, cond_pred);
+            CV_Assert(has_result);
+            return true;
+        }
+#else
+        CV_Error(Error::StsNotImplemented, "OpenCV has been built without async waiting support (C++11 is required)");
+#endif
+    }
+
+    AsyncArray getArrayResult()
+    {
+        CV_Assert(refcount_future == 0);
+        AsyncArray result;
+        addrefFuture();
+        result.p = this;
+        future_is_returned = true;
+        return result;
+    }
+
+    void setValue(InputArray value)
+    {
+        if (future_is_returned && refcount_future == 0)
+            CV_Error(Error::StsError, "Associated AsyncArray has been destroyed");
+#ifdef CV_CXX11
+        std::unique_lock<std::mutex> lock(mtx);
+#else
+        cv::AutoLock lock(mtx);
+#endif
+        CV_Assert(!has_result);
+        int k = value.kind();
+        if (k == _InputArray::UMAT)
+        {
+            result_umat = makePtr<UMat>();
+            value.copyTo(*result_umat.get());
+        }
+        else
+        {
+            result_mat = makePtr<Mat>();
+            value.copyTo(*result_mat.get());
+        }
+        has_result = true;
+#ifdef CV_CXX11
+        cond_var.notify_all();
+#endif
+    }
+
+#if CV__EXCEPTION_PTR
+    void setException(std::exception_ptr e)
+    {
+        if (future_is_returned && refcount_future == 0)
+            CV_Error(Error::StsError, "Associated AsyncArray has been destroyed");
+#ifdef CV_CXX11
+        std::unique_lock<std::mutex> lock(mtx);
+#else
+        cv::AutoLock lock(mtx);
+#endif
+        CV_Assert(!has_result);
+        has_exception = true;
+        exception = e;
+        has_result = true;
+#ifdef CV_CXX11
+        cond_var.notify_all();
+#endif
+    }
+#endif
+
+    void setException(const cv::Exception e)
+    {
+        if (future_is_returned && refcount_future == 0)
+            CV_Error(Error::StsError, "Associated AsyncArray has been destroyed");
+#ifdef CV_CXX11
+        std::unique_lock<std::mutex> lock(mtx);
+#else
+        cv::AutoLock lock(mtx);
+#endif
+        CV_Assert(!has_result);
+        has_exception = true;
+        cv_exception = e;
+        has_result = true;
+#ifdef CV_CXX11
+        cond_var.notify_all();
+#endif
+    }
+};
+
+
+AsyncArray::AsyncArray() CV_NOEXCEPT
+    : p(NULL)
+{
+}
+
+AsyncArray::~AsyncArray() CV_NOEXCEPT
+{
+    release();
+}
+
+AsyncArray::AsyncArray(const AsyncArray& o) CV_NOEXCEPT
+    : p(o.p)
+{
+    if (p)
+        p->addrefFuture();
+}
+
+AsyncArray& AsyncArray::operator=(const AsyncArray& o) CV_NOEXCEPT
+{
+    Impl* newp = o.p;
+    if (newp)
+        newp->addrefFuture();
+    release();
+    p = newp;
+    return *this;
+}
+
+void AsyncArray::release() CV_NOEXCEPT
+{
+    Impl* impl = p;
+    p = NULL;
+    if (impl)
+        impl->releaseFuture();
+}
+
+bool AsyncArray::get(OutputArray dst, int64 timeoutNs) const
+{
+    CV_Assert(p);
+    return p->get(dst, timeoutNs);
+}
+
+void AsyncArray::get(OutputArray dst) const
+{
+    CV_Assert(p);
+    bool res = p->get(dst, -1);
+    CV_Assert(res);
+}
+
+bool AsyncArray::wait_for(int64 timeoutNs) const
+{
+    CV_Assert(p);
+    return p->wait_for(timeoutNs);
+}
+
+bool AsyncArray::valid() const CV_NOEXCEPT
+{
+    if (!p) return false;
+    return p->valid();
+}
+
+
+//
+// AsyncPromise
+//
+
+AsyncPromise::AsyncPromise() CV_NOEXCEPT
+    : p(new AsyncArray::Impl())
+{
+}
+
+AsyncPromise::~AsyncPromise() CV_NOEXCEPT
+{
+    release();
+}
+
+AsyncPromise::AsyncPromise(const AsyncPromise& o) CV_NOEXCEPT
+    : p(o.p)
+{
+    if (p)
+        p->addrefPromise();
+}
+
+AsyncPromise& AsyncPromise::operator=(const AsyncPromise& o) CV_NOEXCEPT
+{
+    Impl* newp = o.p;
+    if (newp)
+        newp->addrefPromise();
+    release();
+    p = newp;
+    return *this;
+}
+
+void AsyncPromise::release() CV_NOEXCEPT
+{
+    Impl* impl = p;
+    p = NULL;
+    if (impl)
+        impl->releasePromise();
+}
+
+AsyncArray AsyncPromise::getArrayResult()
+{
+    CV_Assert(p);
+    return p->getArrayResult();
+}
+
+void AsyncPromise::setValue(InputArray value)
+{
+    CV_Assert(p);
+    return p->setValue(value);
+}
+
+void AsyncPromise::setException(const cv::Exception& exception)
+{
+    CV_Assert(p);
+    return p->setException(exception);
+}
+
+#if CV__EXCEPTION_PTR
+void AsyncPromise::setException(std::exception_ptr exception)
+{
+    CV_Assert(p);
+    return p->setException(exception);
+}
+#endif
+
+} // namespace

modules/core/src/matrix_wrap.cpp

@@ -1879,6 +1879,76 @@ void _OutputArray::assign(const Mat& m) const
 }
 
 
+void _OutputArray::move(UMat& u) const
+{
+    if (fixedSize())
+    {
+        // TODO Performance warning
+        assign(u);
+        return;
+    }
+    int k = kind();
+    if (k == UMAT)
+    {
+#ifdef CV_CXX11
+        *(UMat*)obj = std::move(u);
+#else
+        *(UMat*)obj = u;
+        u.release();
+#endif
+    }
+    else if (k == MAT)
+    {
+        u.copyTo(*(Mat*)obj); // TODO check u.getMat()
+        u.release();
+    }
+    else if (k == MATX)
+    {
+        u.copyTo(getMat()); // TODO check u.getMat()
+        u.release();
+    }
+    else
+    {
+        CV_Error(Error::StsNotImplemented, "");
+    }
+}
+
+
+void _OutputArray::move(Mat& m) const
+{
+    if (fixedSize())
+    {
+        // TODO Performance warning
+        assign(m);
+        return;
+    }
+    int k = kind();
+    if (k == UMAT)
+    {
+        m.copyTo(*(UMat*)obj); // TODO check m.getUMat()
+        m.release();
+    }
+    else if (k == MAT)
+    {
+#ifdef CV_CXX11
+        *(Mat*)obj = std::move(m);
+#else
+        *(Mat*)obj = m;
+        m.release();
+#endif
+    }
+    else if (k == MATX)
+    {
+        m.copyTo(getMat());
+        m.release();
+    }
+    else
+    {
+        CV_Error(Error::StsNotImplemented, "");
+    }
+}
+
+
 void _OutputArray::assign(const std::vector<UMat>& v) const
 {
     int k = kind();

modules/core/src/parallel.cpp

@@ -129,27 +129,7 @@
 
 #include "parallel_impl.hpp"
 
-
-#ifndef CV__EXCEPTION_PTR
-#  if defined(__ANDROID__) && defined(ATOMIC_INT_LOCK_FREE) && ATOMIC_INT_LOCK_FREE < 2
-#    define CV__EXCEPTION_PTR 0  // Not supported, details: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58938
-#  elif defined(CV_CXX11)
-#    define CV__EXCEPTION_PTR 1
-#  elif defined(_MSC_VER)
-#    define CV__EXCEPTION_PTR (_MSC_VER >= 1600)
-#  elif defined(__clang__)
-#    define CV__EXCEPTION_PTR 0  // C++11 only (see above)
-#  elif defined(__GNUC__) && defined(__GXX_EXPERIMENTAL_CXX0X__)
-#    define CV__EXCEPTION_PTR (__GXX_EXPERIMENTAL_CXX0X__ > 0)
-#  endif
-#endif
-#ifndef CV__EXCEPTION_PTR
-#  define CV__EXCEPTION_PTR 0
-#elif CV__EXCEPTION_PTR
-#  include <exception>  // std::exception_ptr
-#endif
-
-
+#include "opencv2/core/detail/exception_ptr.hpp"  // CV__EXCEPTION_PTR = 1 if std::exception_ptr is available
 
 using namespace cv;
 

modules/core/test/test_async.cpp

@@ -0,0 +1,154 @@
+// This file is part of OpenCV project.
+// It is subject to the license terms in the LICENSE file found in the top-level directory
+// of this distribution and at http://opencv.org/license.html.
+#include "test_precomp.hpp"
+#include <opencv2/core/async.hpp>
+#include <opencv2/core/detail/async_promise.hpp>
+
+#include <opencv2/core/bindings_utils.hpp>
+
+#ifdef CV_CXX11
+#include <thread>
+#include <chrono>
+#endif
+
+namespace opencv_test { namespace {
+
+TEST(Core_Async, BasicCheck)
+{
+    Mat m(3, 3, CV_32FC1, Scalar::all(5.0f));
+    AsyncPromise p;
+    AsyncArray r = p.getArrayResult();
+    EXPECT_TRUE(r.valid());
+
+    // Follow the limitations of std::promise::get_future
+    // https://en.cppreference.com/w/cpp/thread/promise/get_future
+    EXPECT_THROW(AsyncArray r2 = p.getArrayResult(), cv::Exception);
+
+    p.setValue(m);
+
+    Mat m2;
+    r.get(m2);
+    EXPECT_EQ(0, cvtest::norm(m, m2, NORM_INF));
+
+    // Follow the limitations of std::future::get
+    // https://en.cppreference.com/w/cpp/thread/future/get
+    EXPECT_FALSE(r.valid());
+    Mat m3;
+    EXPECT_THROW(r.get(m3), cv::Exception);
+}
+
+TEST(Core_Async, ExceptionCheck)
+{
+    Mat m(3, 3, CV_32FC1, Scalar::all(5.0f));
+    AsyncPromise p;
+    AsyncArray r = p.getArrayResult();
+    EXPECT_TRUE(r.valid());
+
+    try
+    {
+        CV_Error(Error::StsOk, "Test: Generated async error");
+    }
+    catch (const cv::Exception& e)
+    {
+        p.setException(e);
+    }
+
+    try {
+        Mat m2;
+        r.get(m2);
+        FAIL() << "Exception is expected";
+    }
+    catch (const cv::Exception& e)
+    {
+        EXPECT_EQ(Error::StsOk, e.code) << e.what();
+    }
+
+    // Follow the limitations of std::future::get
+    // https://en.cppreference.com/w/cpp/thread/future/get
+    EXPECT_FALSE(r.valid());
+}
+
+
+TEST(Core_Async, LikePythonTest)
+{
+    Mat m(3, 3, CV_32FC1, Scalar::all(5.0f));
+    AsyncArray r = cv::utils::testAsyncArray(m);
+    EXPECT_TRUE(r.valid());
+    Mat m2;
+    r.get(m2);
+    EXPECT_EQ(0, cvtest::norm(m, m2, NORM_INF));
+
+    // Follow the limitations of std::future::get
+    // https://en.cppreference.com/w/cpp/thread/future/get
+    EXPECT_FALSE(r.valid());
+}
+
+
+#ifdef CV_CXX11
+TEST(Core_Async, AsyncThread_Simple)
+{
+    Mat m(3, 3, CV_32FC1, Scalar::all(5.0f));
+    AsyncPromise p;
+    AsyncArray r = p.getArrayResult();
+
+    std::thread t([&]{
+        std::this_thread::sleep_for(std::chrono::milliseconds(100));
+        try {
+            p.setValue(m);
+        } catch (const std::exception& e) {
+            std::cout << e.what() << std::endl;
+        } catch (...) {
+            std::cout << "Unknown C++ exception" << std::endl;
+        }
+    });
+
+    try
+    {
+        Mat m2;
+        r.get(m2);
+        EXPECT_EQ(0, cvtest::norm(m, m2, NORM_INF));
+
+        t.join();
+    }
+    catch (...)
+    {
+        t.join();
+        throw;
+    }
+}
+
+TEST(Core_Async, AsyncThread_DetachedResult)
+{
+    Mat m(3, 3, CV_32FC1, Scalar::all(5.0f));
+    AsyncPromise p;
+    {
+        AsyncArray r = p.getArrayResult();
+        r.release();
+    }
+
+    bool exception_ok = false;
+
+    std::thread t([&]{
+        std::this_thread::sleep_for(std::chrono::milliseconds(100));
+        try {
+            p.setValue(m);
+        } catch (const cv::Exception& e) {
+            if (e.code == Error::StsError)
+                exception_ok = true;
+            else
+                std::cout << e.what() << std::endl;
+        } catch (const std::exception& e) {
+            std::cout << e.what() << std::endl;
+        } catch (...) {
+            std::cout << "Unknown C++ exception" << std::endl;
+        }
+    });
+    t.join();
+
+    EXPECT_TRUE(exception_ok);
+}
+
+#endif
+
+}} // namespace

modules/dnn/include/opencv2/dnn/dnn.hpp

@@ -44,9 +44,7 @@
 
 #include <vector>
 #include <opencv2/core.hpp>
-#ifdef CV_CXX11
-#include <future>
-#endif
+#include "opencv2/core/async.hpp"
 
 #if !defined CV_DOXYGEN && !defined CV_STATIC_ANALYSIS && !defined CV_DNN_DONT_ADD_EXPERIMENTAL_NS
 #define CV__DNN_EXPERIMENTAL_NS_BEGIN namespace experimental_dnn_34_v12 {
@@ -67,18 +65,6 @@ CV__DNN_EXPERIMENTAL_NS_BEGIN
 
     typedef std::vector<int> MatShape;
 
-#if defined(CV_CXX11) || defined(CV_DOXYGEN)
-    typedef std::future<Mat> AsyncMat;
-#else
-    // Just a workaround for bindings.
-    struct AsyncMat
-    {
-        Mat get() { return Mat(); }
-        void wait() const {}
-        size_t wait_for(size_t milliseconds) const { CV_UNUSED(milliseconds); return -1; }
-    };
-#endif
-
     /**
      * @brief Enum of computation backends supported by layers.
      * @see Net::setPreferableBackend
@@ -483,7 +469,7 @@ CV__DNN_EXPERIMENTAL_NS_BEGIN
          *  This is an asynchronous version of forward(const String&).
          *  dnn::DNN_BACKEND_INFERENCE_ENGINE backend is required.
          */
-        CV_WRAP AsyncMat forwardAsync(const String& outputName = String());
+        CV_WRAP AsyncArray forwardAsync(const String& outputName = String());
 
         /** @brief Runs forward pass to compute output of layer with name @p outputName.
          *  @param outputBlobs contains all output blobs for specified layer.

modules/dnn/misc/python/pyopencv_dnn.hpp

@@ -2,13 +2,6 @@
 typedef dnn::DictValue LayerId;
 typedef std::vector<dnn::MatShape> vector_MatShape;
 typedef std::vector<std::vector<dnn::MatShape> > vector_vector_MatShape;
-#ifdef CV_CXX11
-typedef std::chrono::milliseconds chrono_milliseconds;
-typedef std::future_status AsyncMatStatus;
-#else
-typedef size_t chrono_milliseconds;
-typedef size_t AsyncMatStatus;
-#endif
 
 template<>
 bool pyopencv_to(PyObject *o, dnn::DictValue &dv, const char *name)
@@ -46,46 +39,6 @@ bool pyopencv_to(PyObject *o, std::vector<Mat> &blobs, const char *name) //requi
   return pyopencvVecConverter<Mat>::to(o, blobs, ArgInfo(name, false));
 }
 
-#ifdef CV_CXX11
-
-template<>
-PyObject* pyopencv_from(const std::future<Mat>& f_)
-{
-    std::future<Mat>& f = const_cast<std::future<Mat>&>(f_);
-    Ptr<cv::dnn::AsyncMat> p(new std::future<Mat>(std::move(f)));
-    return pyopencv_from(p);
-}
-
-template<>
-PyObject* pyopencv_from(const std::future_status& status)
-{
-    return pyopencv_from((int)status);
-}
-
-template<>
-bool pyopencv_to(PyObject* src, std::chrono::milliseconds& dst, const char* name)
-{
-    size_t millis = 0;
-    if (pyopencv_to(src, millis, name))
-    {
-        dst = std::chrono::milliseconds(millis);
-        return true;
-    }
-    else
-        return false;
-}
-
-#else
-
-template<>
-PyObject* pyopencv_from(const cv::dnn::AsyncMat&)
-{
-    CV_Error(Error::StsNotImplemented, "C++11 is required.");
-    return 0;
-}
-
-#endif  // CV_CXX11
-
 template<typename T>
 PyObject* pyopencv_from(const dnn::DictValue &dv)
 {

modules/dnn/misc/python/shadow_async_mat.hpp

@@ -1,22 +0,0 @@
-#error This is a shadow header file, which is not intended for processing by any compiler. \
-       Only bindings parser should handle this file.
-
-namespace cv { namespace dnn {
-
-class CV_EXPORTS_W AsyncMat
-{
-public:
-    //! Wait for Mat object readiness and return it.
-    CV_WRAP Mat get();
-
-    //! Wait for Mat object readiness.
-    CV_WRAP void wait() const;
-
-    /** @brief Wait for Mat object readiness specific amount of time.
-     *  @param timeout Timeout in milliseconds
-     *  @returns [std::future_status](https://en.cppreference.com/w/cpp/thread/future_status)
-     */
-    CV_WRAP AsyncMatStatus wait_for(std::chrono::milliseconds timeout) const;
-};
-
-}}

modules/dnn/misc/python/test/test_dnn.py

@@ -69,8 +69,9 @@ def printParams(backend, target):
 
 class dnn_test(NewOpenCVTests):
 
-    def __init__(self, *args, **kwargs):
-        super(dnn_test, self).__init__(*args, **kwargs)
+    def setUp(self):
+        super(dnn_test, self).setUp()
+
         self.dnnBackendsAndTargets = [
             [cv.dnn.DNN_BACKEND_OPENCV, cv.dnn.DNN_TARGET_CPU],
         ]
@@ -168,7 +169,7 @@ class dnn_test(NewOpenCVTests):
             normAssertDetections(self, ref, out, 0.5, scoresDiff, iouDiff)
 
     def test_async(self):
-        timeout = 5000  # in milliseconds
+        timeout = 500*10**6  # in nanoseconds (500ms)
         testdata_required = bool(os.environ.get('OPENCV_DNN_TEST_REQUIRE_TESTDATA', False))
         proto = self.find_dnn_file('dnn/layers/layer_convolution.prototxt', required=testdata_required)
         model = self.find_dnn_file('dnn/layers/layer_convolution.caffemodel', required=testdata_required)
@@ -209,11 +210,9 @@ class dnn_test(NewOpenCVTests):
                 outs.insert(0, netAsync.forwardAsync())
 
             for i in reversed(range(numInputs)):
-                ret = outs[i].wait_for(timeout)
-                if ret == 1:
-                    self.fail("Timeout")
-                self.assertEqual(ret, 0)  # is ready
-                normAssert(self, refs[i], outs[i].get(), 'Index: %d' % i, 1e-10)
+                ret, result = outs[i].get(timeoutNs=float(timeout))
+                self.assertTrue(ret)
+                normAssert(self, refs[i], result, 'Index: %d' % i, 1e-10)
 
 
 if __name__ == '__main__':

modules/dnn/src/dnn.cpp

@@ -2557,7 +2557,7 @@ struct Net::Impl
     }
 
 #ifdef CV_CXX11
-    std::future<Mat> getBlobAsync(const LayerPin& pin)
+    AsyncArray getBlobAsync(const LayerPin& pin)
     {
         CV_TRACE_FUNCTION();
 #ifdef HAVE_INF_ENGINE
@@ -2586,7 +2586,7 @@ struct Net::Impl
 #endif
     }
 
-    std::future<Mat> getBlobAsync(String outputName)
+    AsyncArray getBlobAsync(String outputName)
     {
         return getBlobAsync(getPinByAlias(outputName));
     }
@@ -2714,7 +2714,7 @@ Mat Net::forward(const String& outputName)
     return impl->getBlob(layerName);
 }
 
-AsyncMat Net::forwardAsync(const String& outputName)
+AsyncArray Net::forwardAsync(const String& outputName)
 {
     CV_TRACE_FUNCTION();
 #ifdef CV_CXX11

modules/dnn/src/op_inf_engine.cpp

@@ -849,7 +849,7 @@ void InfEngineBackendNet::InfEngineReqWrapper::makePromises(const std::vector<Pt
     outsNames.resize(outs.size());
     for (int i = 0; i < outs.size(); ++i)
     {
-        outs[i]->futureMat = outProms[i].get_future();
+        outs[i]->futureMat = outProms[i].getArrayResult();
         outsNames[i] = outs[i]->dataPtr->name;
     }
 }
@@ -906,20 +906,38 @@ void InfEngineBackendNet::forward(const std::vector<Ptr<BackendWrapper> >& outBl
             {
                 InfEngineReqWrapper* wrapper;
                 request->GetUserData((void**)&wrapper, 0);
-                CV_Assert(wrapper);
+                CV_Assert(wrapper && "Internal error");
 
-                for (int i = 0; i < wrapper->outProms.size(); ++i)
+                size_t processedOutputs = 0;
+                try
                 {
-                    const std::string& name = wrapper->outsNames[i];
-                    Mat m = infEngineBlobToMat(wrapper->req.GetBlob(name));
+                    for (; processedOutputs < wrapper->outProms.size(); ++processedOutputs)
+                    {
+                        const std::string& name = wrapper->outsNames[processedOutputs];
+                        Mat m = infEngineBlobToMat(wrapper->req.GetBlob(name));
 
-                    if (status == InferenceEngine::StatusCode::OK)
-                        wrapper->outProms[i].set_value(m.clone());
-                    else
+                        try
+                        {
+                            CV_Assert(status == InferenceEngine::StatusCode::OK);
+                            wrapper->outProms[processedOutputs].setValue(m.clone());
+                        }
+                        catch (...)
+                        {
+                            try {
+                                wrapper->outProms[processedOutputs].setException(std::current_exception());
+                            } catch(...) {
+                                CV_LOG_ERROR(NULL, "DNN: Exception occured during async inference exception propagation");
+                            }
+                        }
+                    }
+                }
+                catch (...)
+                {
+                    std::exception_ptr e = std::current_exception();
+                    for (; processedOutputs < wrapper->outProms.size(); ++processedOutputs)
                     {
                         try {
-                            std::runtime_error e("Async request failed");
-                            wrapper->outProms[i].set_exception(std::make_exception_ptr(e));
+                            wrapper->outProms[processedOutputs].setException(e);
                         } catch(...) {
                             CV_LOG_ERROR(NULL, "DNN: Exception occured during async inference exception propagation");
                         }

modules/dnn/src/op_inf_engine.hpp

@@ -12,6 +12,9 @@
 #include "opencv2/core/cvstd.hpp"
 #include "opencv2/dnn.hpp"
 
+#include "opencv2/core/async.hpp"
+#include "opencv2/core/detail/async_promise.hpp"
+
 #include "opencv2/dnn/utils/inference_engine.hpp"
 
 #ifdef HAVE_INF_ENGINE
@@ -208,7 +211,7 @@ private:
         void makePromises(const std::vector<Ptr<BackendWrapper> >& outs);
 
         InferenceEngine::InferRequest req;
-        std::vector<std::promise<Mat> > outProms;
+        std::vector<cv::AsyncPromise> outProms;
         std::vector<std::string> outsNames;
         bool isReady;
     };
@@ -264,7 +267,7 @@ public:
 
     InferenceEngine::DataPtr dataPtr;
     InferenceEngine::Blob::Ptr blob;
-    std::future<Mat> futureMat;
+    AsyncArray futureMat;
 };
 
 InferenceEngine::Blob::Ptr wrapToInfEngineBlob(const Mat& m, InferenceEngine::Layout layout = InferenceEngine::Layout::ANY);

modules/dnn/test/test_misc.cpp

@@ -341,12 +341,13 @@ TEST(Net, forwardAndRetrieve)
 }
 
 #ifdef HAVE_INF_ENGINE
+static const std::chrono::milliseconds async_timeout(500);
+
 // This test runs network in synchronous mode for different inputs and then
 // runs the same model asynchronously for the same inputs.
 typedef testing::TestWithParam<tuple<int, Target> > Async;
 TEST_P(Async, set_and_forward_single)
 {
-    static const int kTimeout = 5000;  // in milliseconds.
     const int dtype = get<0>(GetParam());
     const int target = get<1>(GetParam());
 
@@ -383,16 +384,16 @@ TEST_P(Async, set_and_forward_single)
     {
         netAsync.setInput(inputs[i]);
 
-        std::future<Mat> out = netAsync.forwardAsync();
-        if (out.wait_for(std::chrono::milliseconds(kTimeout)) == std::future_status::timeout)
-            CV_Error(Error::StsAssert, "Timeout");
-        normAssert(refs[i], out.get(), format("Index: %d", i).c_str(), 0, 0);
+        AsyncArray out = netAsync.forwardAsync();
+        ASSERT_TRUE(out.valid());
+        Mat result;
+        EXPECT_TRUE(out.get(result, async_timeout));
+        normAssert(refs[i], result, format("Index: %d", i).c_str(), 0, 0);
     }
 }
 
 TEST_P(Async, set_and_forward_all)
 {
-    static const int kTimeout = 5000;  // in milliseconds.
     const int dtype = get<0>(GetParam());
     const int target = get<1>(GetParam());
 
@@ -426,7 +427,7 @@ TEST_P(Async, set_and_forward_all)
     }
 
     // Run asynchronously. To make test more robust, process inputs in the reversed order.
-    std::vector<std::future<Mat> > outs(numInputs);
+    std::vector<AsyncArray> outs(numInputs);
     for (int i = numInputs - 1; i >= 0; --i)
     {
         netAsync.setInput(inputs[i]);
@@ -435,9 +436,10 @@ TEST_P(Async, set_and_forward_all)
 
     for (int i = numInputs - 1; i >= 0; --i)
     {
-        if (outs[i].wait_for(std::chrono::milliseconds(kTimeout)) == std::future_status::timeout)
-            CV_Error(Error::StsAssert, "Timeout");
-        normAssert(refs[i], outs[i].get(), format("Index: %d", i).c_str(), 0, 0);
+        ASSERT_TRUE(outs[i].valid());
+        Mat result;
+        EXPECT_TRUE(outs[i].get(result, async_timeout));
+        normAssert(refs[i], result, format("Index: %d", i).c_str(), 0, 0);
     }
 }
 

modules/python/test/test_async.py

@@ -0,0 +1,33 @@
+#!/usr/bin/env python
+from __future__ import print_function
+
+import numpy as np
+import cv2 as cv
+
+from tests_common import NewOpenCVTests
+
+class AsyncTest(NewOpenCVTests):
+
+    def test_async_simple(self):
+        m = np.array([[1,2],[3,4],[5,6]])
+        async_result = cv.utils.testAsyncArray(m)
+        self.assertTrue(async_result.valid())
+        ret, result = async_result.get(timeoutNs=10**6)  # 1ms
+        self.assertTrue(ret)
+        self.assertFalse(async_result.valid())
+        self.assertEqual(cv.norm(m, result, cv.NORM_INF), 0)
+
+
+    def test_async_exception(self):
+        async_result = cv.utils.testAsyncException()
+        self.assertTrue(async_result.valid())
+        try:
+            _ret, _result = async_result.get(timeoutNs=10**6)  # 1ms
+            self.fail("Exception expected")
+        except cv.error as e:
+            self.assertEqual(cv.Error.StsOk, e.code)
+
+
+
+if __name__ == '__main__':
+    NewOpenCVTests.bootstrap()

samples/dnn/object_detection.cpp

@@ -6,6 +6,7 @@
 #include <opencv2/highgui.hpp>
 
 #ifdef CV_CXX11
+#include <mutex>
 #include <thread>
 #include <queue>
 #endif
@@ -185,7 +186,7 @@ int main(int argc, char** argv)
     QueueFPS<Mat> processedFramesQueue;
     QueueFPS<std::vector<Mat> > predictionsQueue;
     std::thread processingThread([&](){
-        std::queue<std::future<Mat> > futureOutputs;
+        std::queue<AsyncArray> futureOutputs;
         Mat blob;
         while (process)
         {
@@ -224,11 +225,13 @@ int main(int argc, char** argv)
             }
 
             while (!futureOutputs.empty() &&
-                   futureOutputs.front().wait_for(std::chrono::seconds(0)) == std::future_status::ready)
+                   futureOutputs.front().wait_for(std::chrono::seconds(0)))
             {
-                Mat out = futureOutputs.front().get();
-                predictionsQueue.push({out});
+                AsyncArray async_out = futureOutputs.front();
                 futureOutputs.pop();
+                Mat out;
+                async_out.get(out);
+                predictionsQueue.push({out});
             }
         }
     });

samples/dnn/object_detection.py

@@ -4,7 +4,7 @@ import numpy as np
 import sys
 import time
 from threading import Thread
-if sys.version_info[0] == '2':
+if sys.version_info[0] == 2:
     import Queue as queue
 else:
     import queue
@@ -262,7 +262,7 @@ def processingThreadBody():
                 outs = net.forward(outNames)
                 predictionsQueue.put(np.copy(outs))
 
-        while futureOutputs and futureOutputs[0].wait_for(0) == 0:
+        while futureOutputs and futureOutputs[0].wait_for(0):
             out = futureOutputs[0].get()
             predictionsQueue.put(np.copy([out]))