Fix #3167: avoid infinite wait on failure to init curl handle

src/aws-cpp-sdk-core/include/aws/core/utils/ResourceManager.h

@@ -74,6 +74,31 @@ namespace Aws
                 return resource;
             }
 
+            /**
+             * Returns a resource with exclusive ownership or a nullptr.
+             * If resource is available within the wait timeout then the resource is returned.
+             * otherwise (if the timeout has expired or container is shutdown) the nullptr is returned.
+             * You must call Release on the resource when you are finished.
+             * This method is enabled only for pointer RESOURCE_TYPE type.
+             *
+             * @return instance of RESOURCE_TYPE, nullptr if the resource manager is being shutdown
+             */
+            template<typename std::enable_if<std::is_pointer<RESOURCE_TYPE>::value>::type * = nullptr>
+            RESOURCE_TYPE TryAcquire(const uint64_t timeoutMs) {
+              std::unique_lock<std::mutex> locker(m_queueLock);
+              const bool isNotEmpty = m_semaphore.wait_for(locker, std::chrono::milliseconds(timeoutMs),
+                                                           [&]() { return m_shutdown.load() || !m_resources.empty(); });
+
+              if (m_shutdown || !isNotEmpty) {
+                return nullptr;
+              }
+
+              RESOURCE_TYPE resource = m_resources.back();
+              m_resources.pop_back();
+
+              return resource;
+            }
+
             /**
              * Returns whether or not resources are currently available for acquisition
              *
@@ -122,6 +147,7 @@ namespace Aws
             {
                 std::unique_lock<std::mutex> locker(m_queueLock);
                 m_shutdown = true;
+                m_semaphore.notify_all();
 
                 //wait for all acquired resources to be released.
                 while (m_resources.size() < resourceCount)

src/aws-cpp-sdk-core/source/http/curl/CurlHandleContainer.cpp

@@ -32,6 +32,7 @@ CurlHandleContainer::~CurlHandleContainer()
         AWS_LOGSTREAM_DEBUG(CURL_HANDLE_CONTAINER_TAG, "Cleaning up " << handle);
         curl_easy_cleanup(handle);
     }
+    m_poolSize = 0;
 }
 
 CURL* CurlHandleContainer::AcquireCurlHandle()
@@ -44,7 +45,19 @@ CURL* CurlHandleContainer::AcquireCurlHandle()
         CheckAndGrowPool();
     }
 
-    CURL* handle = m_handleContainer.TryAcquire();
+    // TODO: 1.12: start to fail instead of infinite loop
+    CURL* handle = nullptr;
+    bool errorLogged = false; // avoid log explosion on legacy app behavior
+    while (!handle && m_poolSize) {
+      constexpr unsigned long DEFAULT_TIMEOUT = 1000l;
+      handle = m_handleContainer.TryAcquire(std::max(m_connectTimeout, DEFAULT_TIMEOUT));
+      if (!handle && !errorLogged) {
+        AWS_LOGSTREAM_ERROR(CURL_HANDLE_CONTAINER_TAG, "Unable to Acquire a curl handle within the specified connect timeout: "
+                   << m_connectTimeout << ". Waiting further, this method will start failing in 1.12.x. "
+                   "Please increase the pool size or the connect timeout value.");
+        errorLogged = true;
+      }
+    }
     AWS_LOGSTREAM_DEBUG(CURL_HANDLE_CONTAINER_TAG, "Connection has been released. Continuing.");
     AWS_LOGSTREAM_DEBUG(CURL_HANDLE_CONTAINER_TAG, "Returning connection handle " << handle);
     return handle;
@@ -80,10 +93,15 @@ void CurlHandleContainer::DestroyCurlHandle(CURL* handle)
         // If the handle is not released back to the pool, it could create a deadlock
         // Create a new handle and release that into the pool
         handle = CreateCurlHandleInPool();
+        if (!handle && m_poolSize) {
+          m_poolSize -= 1;
+        }
     }
     if (handle)
     {
         AWS_LOGSTREAM_DEBUG(CURL_HANDLE_CONTAINER_TAG, "Created replacement handle and released to pool: " << handle);
+    } else {
+      AWS_LOGSTREAM_ERROR(CURL_HANDLE_CONTAINER_TAG, "Failed to create a replacement handle. The handle pool size reduced to " << m_poolSize);
     }
 }