Connection Reuse Test (#4664)

* Connection Reuse Test

sdk/storage/azure-storage-blobs/test/ut/CMakeLists.txt

@@ -27,6 +27,7 @@ add_executable (
     blob_service_client_test.cpp
     block_blob_client_test.cpp
     block_blob_client_test.hpp
+    connection_reuse_test.cpp
     macro_guard.cpp
     page_blob_client_test.cpp
     page_blob_client_test.hpp

sdk/storage/azure-storage-blobs/test/ut/connection_reuse_test.cpp

@@ -0,0 +1,57 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+#include "block_blob_client_test.hpp"
+
+namespace Azure { namespace Storage { namespace Test {
+
+  // If connection is reused, the requests with the same connection should hit the same sever. So
+  // this test verifies whether a series of requests hit the same server.
+  TEST_F(BlockBlobClientTest, IsConnectionReused_LIVEONLY_)
+  {
+    const std::string containerName = LowercaseRandomString();
+    const std::string blobName = LowercaseRandomString();
+
+    auto containerClient1 = GetBlobContainerClientForTest(containerName + "1");
+    auto containerClient2 = GetBlobContainerClientForTest(containerName + "2");
+    containerClient1.Create();
+    containerClient2.Create();
+
+    auto buffer = RandomBuffer(100);
+    Core::IO::MemoryBodyStream bodyStream(buffer.data(), buffer.size());
+
+    std::vector<Azure::Storage::Blobs::BlockBlobClient> blobClients;
+    for (int i = 0; i < 5; ++i)
+    {
+      blobClients.push_back(containerClient1.GetBlockBlobClient(blobName + std::to_string(i)));
+      blobClients.push_back(containerClient2.GetBlockBlobClient(blobName + std::to_string(i)));
+    }
+    std::unordered_set<std::string> distinctServers;
+    size_t totalHitCount = 0;
+
+    auto updateDistinctServers = [&](const Azure::Core::CaseInsensitiveMap& headers) {
+      // The third part of a storage request id means the server node id.
+      // For Example, RequestId:3bcf963b-601e-0054-1f40-910c39000000, '0054' is the server node
+      // which served this request.
+      std::string serverId = headers.find("x-ms-request-id")->second.substr(14, 4);
+      distinctServers.insert(serverId);
+    };
+
+    for (auto& blobClient : blobClients)
+    {
+      auto uploadResult = blobClient.Upload(bodyStream);
+      updateDistinctServers(uploadResult.RawResponse->GetHeaders());
+      ++totalHitCount;
+      auto downloadResult = blobClient.Download();
+      ReadBodyStream(downloadResult.Value.BodyStream);
+      updateDistinctServers(downloadResult.RawResponse->GetHeaders());
+      ++totalHitCount;
+      auto deleteResult = blobClient.Delete();
+      updateDistinctServers(deleteResult.RawResponse->GetHeaders());
+      ++totalHitCount;
+    }
+
+    size_t distinctServersLessThan = totalHitCount / 5;
+    EXPECT_TRUE(distinctServers.size() < distinctServersLessThan);
+  }
+}}} // namespace Azure::Storage::Test