Export methods to set/get the ambient scheduler in cpprest dll (#670)

* Export methods to set/get the ambient scheduler in cpprest dll

* move the definiation of get/set_cpprestsdk_ambient_scheduler to pplxwin.cpp

* Add test for http request with ambient scheduler

Author: chakrab-msft

Release/include/pplx/pplxtasks.h

@@ -16,9 +16,27 @@
 #ifndef _PPLXTASKS_H
 #define _PPLXTASKS_H
 
+#include "cpprest/details/cpprest_compat.h"
+
 #if (defined(_MSC_VER) && (_MSC_VER >= 1800)) && !CPPREST_FORCE_PPLX
 #include <ppltasks.h>
 namespace pplx = Concurrency;
+
+namespace Concurrency
+{
+
+/// <summary>
+/// Sets the ambient scheduler to be used by the PPL constructs.
+/// </summary>
+_ASYNCRTIMP void __cdecl set_cpprestsdk_ambient_scheduler(const std::shared_ptr<scheduler_interface>& _Scheduler);
+
+/// <summary>
+/// Gets the ambient scheduler to be used by the PPL constructs
+/// </summary>
+_ASYNCRTIMP const std::shared_ptr<scheduler_interface>& __cdecl get_cpprestsdk_ambient_scheduler();
+
+} // namespace Concurrency
+
 #if (_MSC_VER >= 1900)
 #include <concrt.h>
 namespace Concurrency {

Release/src/CMakeLists.txt

@@ -103,6 +103,7 @@ elseif(CPPREST_PPLX_IMPL STREQUAL "linux")
     install(FILES ../include/pplx/threadpool.h DESTINATION include/pplx)
   endif()
 elseif(CPPREST_PPLX_IMPL STREQUAL "win")
+  target_sources(cpprest PRIVATE pplx/pplxwin.cpp)
   if(CPPREST_WEBSOCKETS_IMPL STREQUAL "wspp")
     target_sources(cpprest PRIVATE pplx/threadpool.cpp ../include/pplx/threadpool.h)
     if(CPPREST_INSTALL_HEADERS)

Release/src/pplx/pplxwin.cpp

@@ -275,4 +275,19 @@ namespace details
 
 } // namespace pplx
 
+#else
+namespace Concurrency
+{
+
+void __cdecl set_cpprestsdk_ambient_scheduler(const std::shared_ptr<scheduler_interface>& _Scheduler)
+{
+    pplx::set_ambient_scheduler(_Scheduler);
+}
+
+const std::shared_ptr<scheduler_interface>& __cdecl get_cpprestsdk_ambient_scheduler()
+{
+    return pplx::get_ambient_scheduler();
+}
+
+} // namespace pplx
 #endif

Release/tests/functional/http/client/outside_tests.cpp

@@ -111,6 +111,43 @@ TEST_FIXTURE(uri_address, multiple_https_requests)
     });
 }
 
+#if (defined(_MSC_VER) && (_MSC_VER >= 1800)) && !CPPREST_FORCE_PPLX
+TEST_FIXTURE(uri_address, multiple_https_requests_sync_scheduler)
+{
+    struct sync_scheduler : public scheduler_interface
+    {
+    public:
+        virtual void schedule(TaskProc_t function, PVOID context) override
+        {
+            function(context);
+        }
+    };
+
+    // Save the current ambient scheduler
+    const auto scheduler = get_cpprestsdk_ambient_scheduler();
+
+    // Change the ambient scheduler to one that schedules synchronously
+    static std::shared_ptr<scheduler_interface> syncScheduler = std::make_shared<sync_scheduler>();
+    set_cpprestsdk_ambient_scheduler(syncScheduler);
+
+    handle_timeout([&] {
+        // Use code.google.com instead of www.google.com, which redirects
+        http_client client(U("https://code.google.com"));
+
+        http_response response;
+        for (int i = 0; i < 5; ++i)
+        {
+            response = client.request(methods::GET).get();
+            VERIFY_ARE_EQUAL(status_codes::OK, response.status_code());
+            response.content_ready().wait();
+        }
+    });
+
+    // Revert to the original scheduler
+    set_cpprestsdk_ambient_scheduler(scheduler);
+}
+#endif
+
 TEST_FIXTURE(uri_address, reading_google_stream)
 {
     handle_timeout([&]