create async http api, implement in crt

.changelog/feature-async-http-api.json

@@ -0,0 +1,6 @@
+{
+  "type": "feature",
+  "category": "aws-cpp-sdk-core",
+  "contributor": "sbiscigl",
+  "description": "create async http api"
+}

src/aws-cpp-sdk-core/include/aws/core/http/HttpClient.h

@@ -91,6 +91,28 @@ namespace Aws
                 false};
             }
 
+            /**
+             * Starts an http request and returns as soon as it has been started. onResponseComplete is
+             * invoked with the finished response, on whichever thread the implementation completes on.
+             * Only implemented by http clients that can drive a request without a thread of their own.
+             */
+            virtual Aws::Crt::Optional<Aws::Client::AWSError<Aws::Client::CoreErrors>> MakeRequestAsync(
+                const std::shared_ptr<HttpRequest>& request,
+                std::function<void(std::shared_ptr<HttpResponse>)> onResponseComplete,
+                std::function<void(const std::shared_ptr<Aws::Http::Connection>&)> onClientConnectionAvailable = nullptr,
+                Aws::Utils::RateLimits::RateLimiterInterface* readLimiter = nullptr,
+                Aws::Utils::RateLimits::RateLimiterInterface* writeLimiter = nullptr) const {
+              AWS_UNREFERENCED_PARAM(request);
+              AWS_UNREFERENCED_PARAM(onResponseComplete);
+              AWS_UNREFERENCED_PARAM(onClientConnectionAvailable);
+              AWS_UNREFERENCED_PARAM(readLimiter);
+              AWS_UNREFERENCED_PARAM(writeLimiter);
+              return Aws::Client::AWSError<Aws::Client::CoreErrors>{Aws::Client::CoreErrors::NOT_IMPLEMENTED,
+                "NotImplemented",
+                "async requests are not supported on this http client",
+                false};
+            }
+
         protected:
             bool m_bad;
 

src/aws-cpp-sdk-core/include/aws/core/http/HttpConnection.h

@@ -18,6 +18,7 @@ class AWS_CORE_API Connection {
   virtual std::shared_ptr<Aws::Http::ClientStream> NewClientStream(
     const std::shared_ptr<HttpRequest>& request,
     std::function<void(int errorCode)> onStreamComplete) = 0;
+  virtual void Close() = 0;
 };
 }  // namespace Http
 }  // namespace Aws

src/aws-cpp-sdk-core/include/aws/core/http/crt/CRTHttpClient.h

@@ -33,6 +33,14 @@ namespace Aws
         struct ClientConfiguration;
     } // namespace Client
 
+    namespace Utils
+    {
+        namespace Threading
+        {
+            class WaitGroup;
+        }
+    }
+
     namespace Http
     {
         /**
@@ -52,6 +60,13 @@ namespace Aws
                 Aws::Utils::RateLimits::RateLimiterInterface* readLimiter,
                 Aws::Utils::RateLimits::RateLimiterInterface* writeLimiter) const override;
 
+            Aws::Crt::Optional<Aws::Client::AWSError<Aws::Client::CoreErrors>> MakeRequestAsync(
+                const std::shared_ptr<HttpRequest>& request,
+                std::function<void(std::shared_ptr<HttpResponse>)> onResponseComplete,
+                std::function<void(const std::shared_ptr<Aws::Http::Connection>&)> onClientConnectionAvailable = nullptr,
+                Aws::Utils::RateLimits::RateLimiterInterface* readLimiter = nullptr,
+                Aws::Utils::RateLimits::RateLimiterInterface* writeLimiter = nullptr) const override;
+
             bool IsDefaultAwsHttpClient() const override { return true; }
 
             Aws::Crt::Optional<Aws::Client::AWSError<Aws::Client::CoreErrors>> AcquireConnection(
@@ -71,6 +86,8 @@ namespace Aws
             Crt::Io::ClientBootstrap& m_bootstrap;
             Client::ClientConfiguration m_configuration;
 
+            std::shared_ptr<Aws::Utils::Threading::WaitGroup> m_requestLatch;
+
             std::shared_ptr<Crt::Http::HttpClientConnectionManager> GetWithCreateConnectionManagerForRequest(const std::shared_ptr<HttpRequest>& request, const Crt::Http::HttpClientConnectionOptions& connectionOptions) const;
             Crt::Http::HttpClientConnectionOptions CreateConnectionOptionsForRequest(const std::shared_ptr<HttpRequest>& request) const;
             void CheckAndInitializeProxySettings(const Aws::Client::ClientConfiguration& clientConfig);

src/aws-cpp-sdk-core/include/aws/core/utils/threading/WaitGroup.h

@@ -0,0 +1,30 @@
+/**
+ * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ * SPDX-License-Identifier: Apache-2.0.
+ */
+
+#pragma once
+
+#include <aws/core/Core_EXPORTS.h>
+#include <aws/core/utils/memory/AWSMemory.h>
+
+#include <cstddef>
+
+namespace Aws {
+namespace Utils {
+namespace Threading {
+class AWS_CORE_API WaitGroup {
+ public:
+  WaitGroup();
+  ~WaitGroup();
+  void Add(size_t count = 1);
+  void Done();
+  void Wait();
+
+ private:
+  struct WaitGroupImpl;
+  Aws::UniquePtr<WaitGroupImpl> m_impl;
+};
+}  // namespace Threading
+}  // namespace Utils
+}  // namespace Aws