Merge branch 'master' into nocopyinterception

48 files changed, 741 insertions, 182 deletions

diff --git a/BUILD b/BUILD
index e3c765198b..cd23d9c91f 100644
--- a/BUILD
+++ b/BUILD
@@ -64,11 +64,11 @@ config_setting(
 )
 
 # This should be updated along with build.yaml
-g_stands_for = "goose"
+g_stands_for = "gold"
 
 core_version = "7.0.0-dev"
 
-version = "1.18.0-dev"
+version = "1.19.0-dev"
 
 GPR_PUBLIC_HDRS = [
     "include/grpc/support/alloc.h",
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 48d3d11d23..7e4dddab5b 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -24,7 +24,7 @@
 cmake_minimum_required(VERSION 2.8)
 
 set(PACKAGE_NAME      "grpc")
-set(PACKAGE_VERSION   "1.18.0-dev")
+set(PACKAGE_VERSION   "1.19.0-dev")
 set(PACKAGE_STRING    "${PACKAGE_NAME} ${PACKAGE_VERSION}")
 set(PACKAGE_TARNAME   "${PACKAGE_NAME}-${PACKAGE_VERSION}")
 set(PACKAGE_BUGREPORT "https://github.com/grpc/grpc/issues/")
diff --git a/Makefile b/Makefile
index b8a1c92186..ce56482a0d 100644
--- a/Makefile
+++ b/Makefile
@@ -438,8 +438,8 @@ Q = @
 endif
 
 CORE_VERSION = 7.0.0-dev
-CPP_VERSION = 1.18.0-dev
-CSHARP_VERSION = 1.18.0-dev
+CPP_VERSION = 1.19.0-dev
+CSHARP_VERSION = 1.19.0-dev
 
 CPPFLAGS_NO_ARCH += $(addprefix -I, $(INCLUDES)) $(addprefix -D, $(DEFINES))
 CPPFLAGS += $(CPPFLAGS_NO_ARCH) $(ARCH_FLAGS)
diff --git a/build.yaml b/build.yaml
index a41decd84f..4ccc452ed5 100644
--- a/build.yaml
+++ b/build.yaml
@@ -13,8 +13,8 @@ settings:
   '#09': Per-language overrides are possible with (eg) ruby_version tag here
   '#10': See the expand_version.py for all the quirks here
   core_version: 7.0.0-dev
-  g_stands_for: goose
-  version: 1.18.0-dev
+  g_stands_for: gold
+  version: 1.19.0-dev
 filegroups:
 - name: alts_proto
   headers:
diff --git a/doc/g_stands_for.md b/doc/g_stands_for.md
index 1e49b4d3f1..7bc8a003b5 100644
--- a/doc/g_stands_for.md
+++ b/doc/g_stands_for.md
@@ -17,4 +17,5 @@
 - 1.15 'g' stands for ['glider'](https://github.com/grpc/grpc/tree/v1.15.x)
 - 1.16 'g' stands for ['gao'](https://github.com/grpc/grpc/tree/v1.16.x)
 - 1.17 'g' stands for ['gizmo'](https://github.com/grpc/grpc/tree/v1.17.x)
-- 1.18 'g' stands for ['goose'](https://github.com/grpc/grpc/tree/master)
+- 1.18 'g' stands for ['goose'](https://github.com/grpc/grpc/tree/v1.18.x)
+- 1.19 'g' stands for ['gold'](https://github.com/grpc/grpc/tree/master)
diff --git a/gRPC-C++.podspec b/gRPC-C++.podspec
index 29a79dd47a..e830958f79 100644
--- a/gRPC-C++.podspec
+++ b/gRPC-C++.podspec
@@ -23,7 +23,7 @@
 Pod::Spec.new do |s|
   s.name     = 'gRPC-C++'
   # TODO (mxyan): use version that match gRPC version when pod is stabilized
-  # version = '1.18.0-dev'
+  # version = '1.19.0-dev'
   version = '0.0.6-dev'
   s.version  = version
   s.summary  = 'gRPC C++ library'
@@ -31,7 +31,7 @@ Pod::Spec.new do |s|
   s.license  = 'Apache License, Version 2.0'
   s.authors  = { 'The gRPC contributors' => 'grpc-packages@google.com' }
 
-  grpc_version = '1.18.0-dev'
+  grpc_version = '1.19.0-dev'
 
   s.source = {
     :git => 'https://github.com/grpc/grpc.git',
diff --git a/gRPC-Core.podspec b/gRPC-Core.podspec
index 240afbff7e..7ddef6aa44 100644
--- a/gRPC-Core.podspec
+++ b/gRPC-Core.podspec
@@ -22,7 +22,7 @@
 
 Pod::Spec.new do |s|
   s.name     = 'gRPC-Core'
-  version = '1.18.0-dev'
+  version = '1.19.0-dev'
   s.version  = version
   s.summary  = 'Core cross-platform gRPC library, written in C'
   s.homepage = 'https://grpc.io'
diff --git a/gRPC-ProtoRPC.podspec b/gRPC-ProtoRPC.podspec
index 13fe3e0b9c..7bf53799de 100644
--- a/gRPC-ProtoRPC.podspec
+++ b/gRPC-ProtoRPC.podspec
@@ -21,7 +21,7 @@
 
 Pod::Spec.new do |s|
   s.name     = 'gRPC-ProtoRPC'
-  version = '1.18.0-dev'
+  version = '1.19.0-dev'
   s.version  = version
   s.summary  = 'RPC library for Protocol Buffers, based on gRPC'
   s.homepage = 'https://grpc.io'
diff --git a/gRPC-RxLibrary.podspec b/gRPC-RxLibrary.podspec
index e132ad41b4..34bec88c8b 100644
--- a/gRPC-RxLibrary.podspec
+++ b/gRPC-RxLibrary.podspec
@@ -21,7 +21,7 @@
 
 Pod::Spec.new do |s|
   s.name     = 'gRPC-RxLibrary'
-  version = '1.18.0-dev'
+  version = '1.19.0-dev'
   s.version  = version
   s.summary  = 'Reactive Extensions library for iOS/OSX.'
   s.homepage = 'https://grpc.io'
diff --git a/gRPC.podspec b/gRPC.podspec
index 940a1ac621..8e284866b3 100644
--- a/gRPC.podspec
+++ b/gRPC.podspec
@@ -20,7 +20,7 @@
 
 Pod::Spec.new do |s|
   s.name     = 'gRPC'
-  version = '1.18.0-dev'
+  version = '1.19.0-dev'
   s.version  = version
   s.summary  = 'gRPC client library for iOS/OSX'
   s.homepage = 'https://grpc.io'
diff --git a/include/grpcpp/impl/codegen/call_op_set.h b/include/grpcpp/impl/codegen/call_op_set.h
index ced0b2ff3e..2c34082ebb 100644
--- a/include/grpcpp/impl/codegen/call_op_set.h
+++ b/include/grpcpp/impl/codegen/call_op_set.h
@@ -317,11 +317,15 @@ class CallOpSendMessage {
 
  protected:
   void AddOp(grpc_op* ops, size_t* nops) {
-    if ((msg_ == nullptr && !send_buf_.Valid()) || hijacked_) return;
+    if (msg_ == nullptr && !send_buf_.Valid()) return;
+    if (hijacked_) {
+      serializer_ = nullptr;
+      return;
+    }
     if (msg_ != nullptr) {
       GPR_CODEGEN_ASSERT(serializer_(msg_).ok());
+      serializer_ = nullptr;
     }
-    serializer_ = nullptr;
     grpc_op* op = &ops[(*nops)++];
     op->op = GRPC_OP_SEND_MESSAGE;
     op->flags = write_options_.flags();
@@ -330,21 +334,38 @@ class CallOpSendMessage {
     // Flags are per-message: clear them after use.
     write_options_.Clear();
   }
-  void FinishOp(bool* status) { send_buf_.Clear(); }
+  void FinishOp(bool* status) {
+    if (msg_ == nullptr && !send_buf_.Valid()) return;
+    if (hijacked_ && failed_send_) {
+      // Hijacking interceptor failed this Op
+      *status = false;
+    } else if (!*status) {
+      // This Op was passed down to core and the Op failed
+      failed_send_ = true;
+    }
+  }
 
   void SetInterceptionHookPoint(
       InterceptorBatchMethodsImpl* interceptor_methods) {
     if (msg_ == nullptr && !send_buf_.Valid()) return;
     interceptor_methods->AddInterceptionHookPoint(
         experimental::InterceptionHookPoints::PRE_SEND_MESSAGE);
-    interceptor_methods->SetSendMessage(&send_buf_, &msg_, serializer_);
+    interceptor_methods->SetSendMessage(&send_buf_, &msg_, &failed_send_,
+                                        serializer_);
   }
 
   void SetFinishInterceptionHookPoint(
       InterceptorBatchMethodsImpl* interceptor_methods) {
+    if (msg_ != nullptr || send_buf_.Valid()) {
+      interceptor_methods->AddInterceptionHookPoint(
+          experimental::InterceptionHookPoints::POST_SEND_MESSAGE);
+    }
+    send_buf_.Clear();
+    msg_ = nullptr;
     // The contents of the SendMessage value that was previously set
     // has had its references stolen by core's operations
-    interceptor_methods->SetSendMessage(nullptr, nullptr, nullptr);
+    interceptor_methods->SetSendMessage(nullptr, nullptr, &failed_send_,
+                                        nullptr);
   }
 
   void SetHijackingState(InterceptorBatchMethodsImpl* interceptor_methods) {
@@ -354,6 +375,7 @@ class CallOpSendMessage {
  private:
   const void* msg_ = nullptr;  // The original non-serialized message
   bool hijacked_ = false;
+  bool failed_send_ = false;
   ByteBuffer send_buf_;
   WriteOptions write_options_;
   std::function<Status(const void*)> serializer_;
@@ -379,6 +401,7 @@ Status CallOpSendMessage::SendMessage(const M& message, WriteOptions options) {
   // Serialize immediately only if we do not have access to the message pointer
   if (msg_ == nullptr) {
     return serializer_(&message);
+    serializer_ = nullptr;
   }
   return Status();
 }
@@ -449,14 +472,16 @@ class CallOpRecvMessage {
 
   void SetInterceptionHookPoint(
       InterceptorBatchMethodsImpl* interceptor_methods) {
-    interceptor_methods->SetRecvMessage(message_);
+    if (message_ == nullptr) return;
+    interceptor_methods->SetRecvMessage(message_, &got_message);
   }
 
   void SetFinishInterceptionHookPoint(
       InterceptorBatchMethodsImpl* interceptor_methods) {
-    if (!got_message) return;
+    if (message_ == nullptr) return;
     interceptor_methods->AddInterceptionHookPoint(
         experimental::InterceptionHookPoints::POST_RECV_MESSAGE);
+    if (!got_message) interceptor_methods->SetRecvMessage(nullptr, nullptr);
   }
   void SetHijackingState(InterceptorBatchMethodsImpl* interceptor_methods) {
     hijacked_ = true;
@@ -544,20 +569,23 @@ class CallOpGenericRecvMessage {
 
   void SetInterceptionHookPoint(
       InterceptorBatchMethodsImpl* interceptor_methods) {
-    interceptor_methods->SetRecvMessage(message_);
+    if (!deserialize_) return;
+    interceptor_methods->SetRecvMessage(message_, &got_message);
   }
 
   void SetFinishInterceptionHookPoint(
       InterceptorBatchMethodsImpl* interceptor_methods) {
-    if (!got_message) return;
+    if (!deserialize_) return;
     interceptor_methods->AddInterceptionHookPoint(
         experimental::InterceptionHookPoints::POST_RECV_MESSAGE);
+    if (!got_message) interceptor_methods->SetRecvMessage(nullptr, nullptr);
   }
   void SetHijackingState(InterceptorBatchMethodsImpl* interceptor_methods) {
     hijacked_ = true;
     if (!deserialize_) return;
     interceptor_methods->AddInterceptionHookPoint(
         experimental::InterceptionHookPoints::PRE_RECV_MESSAGE);
+    got_message = true;
   }
 
  private:
diff --git a/include/grpcpp/impl/codegen/interceptor.h b/include/grpcpp/impl/codegen/interceptor.h
index edf3ab49f1..d749d8578a 100644
--- a/include/grpcpp/impl/codegen/interceptor.h
+++ b/include/grpcpp/impl/codegen/interceptor.h
@@ -46,9 +46,10 @@ namespace experimental {
 /// operation has been requested and it is available. POST_RECV means that a
 /// result is available but has not yet been passed back to the application.
 enum class InterceptionHookPoints {
-  /// The first two in this list are for clients and servers
+  /// The first three in this list are for clients and servers
   PRE_SEND_INITIAL_METADATA,
   PRE_SEND_MESSAGE,
+  POST_SEND_MESSAGE,
   PRE_SEND_STATUS,  // server only
   PRE_SEND_CLOSE,   // client only: WritesDone for stream; after write in unary
   /// The following three are for hijacked clients only and can only be
@@ -119,6 +120,10 @@ class InterceptorBatchMethods {
 
   virtual void ModifySendMessage(const void* message) = 0;
 
+  /// Checks whether the SEND MESSAGE op succeeded. Valid for POST_SEND_MESSAGE
+  /// interceptions.
+  virtual bool GetSendMessageStatus() = 0;
+
   /// Returns a modifiable multimap of the initial metadata to be sent. Valid
   /// for PRE_SEND_INITIAL_METADATA interceptions. A value of nullptr indicates
   /// that this field is not valid.
@@ -164,6 +169,15 @@ class InterceptorBatchMethods {
   /// started from interceptors without infinite regress through the interceptor
   /// list.
   virtual std::unique_ptr<ChannelInterface> GetInterceptedChannel() = 0;
+
+  /// On a hijacked RPC, an interceptor can decide to fail a PRE_RECV_MESSAGE
+  /// op. This would be a signal to the reader that there will be no more
+  /// messages, or the stream has failed or been cancelled.
+  virtual void FailHijackedRecvMessage() = 0;
+
+  /// On a hijacked RPC/ to-be hijacked RPC, this can be called to fail a SEND
+  /// MESSAGE op
+  virtual void FailHijackedSendMessage() = 0;
 };
 
 /// Interface for an interceptor. Interceptor authors must create a class
diff --git a/include/grpcpp/impl/codegen/interceptor_common.h b/include/grpcpp/impl/codegen/interceptor_common.h
index 6fa6210dc3..33e46389b3 100644
--- a/include/grpcpp/impl/codegen/interceptor_common.h
+++ b/include/grpcpp/impl/codegen/interceptor_common.h
@@ -98,6 +98,10 @@ class InterceptorBatchMethodsImpl
     *orig_send_message_ = message;
   }
 
+  bool GetSendMessageStatus() override {
+    return !*fail_send_message_;
+  }
+
   std::multimap<grpc::string, grpc::string>* GetSendInitialMetadata() override {
     return send_initial_metadata_;
   }
@@ -127,15 +131,23 @@ class InterceptorBatchMethodsImpl
 
   Status* GetRecvStatus() override { return recv_status_; }
 
+  void FailHijackedSendMessage() override {
+    GPR_CODEGEN_ASSERT(hooks_[static_cast<size_t>(
+        experimental::InterceptionHookPoints::PRE_SEND_MESSAGE)]);
+    *fail_send_message_ = true;
+  }
+
   std::multimap<grpc::string_ref, grpc::string_ref>* GetRecvTrailingMetadata()
       override {
     return recv_trailing_metadata_->map();
   }
 
   void SetSendMessage(ByteBuffer* buf, const void** msg,
+                      bool* fail_send_message,
                       std::function<Status(const void*)> serializer) {
     send_message_ = buf;
     orig_send_message_ = msg;
+    fail_send_message_ = fail_send_message;
     serializer_ = serializer;
   }
 
@@ -156,7 +168,10 @@ class InterceptorBatchMethodsImpl
     send_trailing_metadata_ = metadata;
   }
 
-  void SetRecvMessage(void* message) { recv_message_ = message; }
+  void SetRecvMessage(void* message, bool* got_message) {
+    recv_message_ = message;
+    got_message_ = got_message;
+  }
 
   void SetRecvInitialMetadata(MetadataMap* map) {
     recv_initial_metadata_ = map;
@@ -179,6 +194,12 @@ class InterceptorBatchMethodsImpl
         info->channel(), current_interceptor_index_ + 1));
   }
 
+  void FailHijackedRecvMessage() override {
+    GPR_CODEGEN_ASSERT(hooks_[static_cast<size_t>(
+        experimental::InterceptionHookPoints::PRE_RECV_MESSAGE)]);
+    *got_message_ = false;
+  }
+
   // Clears all state
   void ClearState() {
     reverse_ = false;
@@ -356,6 +377,7 @@ class InterceptorBatchMethodsImpl
   std::function<void(void)> callback_;
 
   ByteBuffer* send_message_ = nullptr;
+  bool* fail_send_message_ = nullptr;
   const void** orig_send_message_ = nullptr;
   std::function<Status(const void*)> serializer_;
 
@@ -369,6 +391,7 @@ class InterceptorBatchMethodsImpl
   std::multimap<grpc::string, grpc::string>* send_trailing_metadata_ = nullptr;
 
   void* recv_message_ = nullptr;
+  bool* got_message_ = nullptr;
 
   MetadataMap* recv_initial_metadata_ = nullptr;
 
@@ -410,6 +433,14 @@ class CancelInterceptorBatchMethods
     return nullptr;
   }
 
+  bool GetSendMessageStatus() override {
+    GPR_CODEGEN_ASSERT(
+        false &&
+        "It is illegal to call GetSendMessageStatus on a method which "
+        "has a Cancel notification");
+    return false;
+  }
+
   const void* GetSendMessage() override {
     GPR_CODEGEN_ASSERT(
         false &&
@@ -490,6 +521,18 @@ class CancelInterceptorBatchMethods
                        "method which has a Cancel notification");
     return std::unique_ptr<ChannelInterface>(nullptr);
   }
+
+  void FailHijackedRecvMessage() override {
+    GPR_CODEGEN_ASSERT(false &&
+                       "It is illegal to call FailHijackedRecvMessage on a "
+                       "method which has a Cancel notification");
+  }
+
+  void FailHijackedSendMessage() override {
+    GPR_CODEGEN_ASSERT(false &&
+                       "It is illegal to call FailHijackedSendMessage on a "
+                       "method which has a Cancel notification");
+  }
 };
 }  // namespace internal
 }  // namespace grpc
diff --git a/include/grpcpp/impl/codegen/server_interface.h b/include/grpcpp/impl/codegen/server_interface.h
index e0e2629827..890a5650d0 100644
--- a/include/grpcpp/impl/codegen/server_interface.h
+++ b/include/grpcpp/impl/codegen/server_interface.h
@@ -272,7 +272,7 @@ class ServerInterface : public internal::CallHook {
       /* Set interception point for recv message */
       interceptor_methods_.AddInterceptionHookPoint(
           experimental::InterceptionHookPoints::POST_RECV_MESSAGE);
-      interceptor_methods_.SetRecvMessage(request_);
+      interceptor_methods_.SetRecvMessage(request_, nullptr);
       return RegisteredAsyncRequest::FinalizeResult(tag, status);
     }
 
diff --git a/package.xml b/package.xml
index 2632fcb276..d86c204746 100644
--- a/package.xml
+++ b/package.xml
@@ -13,8 +13,8 @@
  <date>2018-01-19</date>
  <time>16:06:07</time>
  <version>
-  <release>1.18.0dev</release>
-  <api>1.18.0dev</api>
+  <release>1.19.0dev</release>
+  <api>1.19.0dev</api>
  </version>
  <stability>
   <release>beta</release>
diff --git a/src/core/lib/surface/version.cc b/src/core/lib/surface/version.cc
index 4829cc80a5..70d7580bec 100644
--- a/src/core/lib/surface/version.cc
+++ b/src/core/lib/surface/version.cc
@@ -25,4 +25,4 @@
 
 const char* grpc_version_string(void) { return "7.0.0-dev"; }
 
-const char* grpc_g_stands_for(void) { return "goose"; }
+const char* grpc_g_stands_for(void) { return "gold"; }
diff --git a/src/cpp/common/version_cc.cc b/src/cpp/common/version_cc.cc
index 55da89e6c8..358131c7c4 100644
--- a/src/cpp/common/version_cc.cc
+++ b/src/cpp/common/version_cc.cc
@@ -22,5 +22,5 @@
 #include <grpcpp/grpcpp.h>
 
 namespace grpc {
-grpc::string Version() { return "1.18.0-dev"; }
+grpc::string Version() { return "1.19.0-dev"; }
 }  // namespace grpc
diff --git a/src/cpp/server/server_cc.cc b/src/cpp/server/server_cc.cc
index 1e3c57446f..13741ce7aa 100644
--- a/src/cpp/server/server_cc.cc
+++ b/src/cpp/server/server_cc.cc
@@ -278,7 +278,7 @@ class Server::SyncRequest final : public internal::CompletionQueueTag {
         request_payload_ = nullptr;
         interceptor_methods_.AddInterceptionHookPoint(
             experimental::InterceptionHookPoints::POST_RECV_MESSAGE);
-        interceptor_methods_.SetRecvMessage(request_);
+        interceptor_methods_.SetRecvMessage(request_, nullptr);
       }
 
       if (interceptor_methods_.RunInterceptors(
@@ -446,7 +446,7 @@ class Server::CallbackRequest final : public internal::CompletionQueueTag {
         req_->request_payload_ = nullptr;
         req_->interceptor_methods_.AddInterceptionHookPoint(
             experimental::InterceptionHookPoints::POST_RECV_MESSAGE);
-        req_->interceptor_methods_.SetRecvMessage(req_->request_);
+        req_->interceptor_methods_.SetRecvMessage(req_->request_, nullptr);
       }
 
       if (req_->interceptor_methods_.RunInterceptors(
diff --git a/src/csharp/Grpc.Core/Version.csproj.include b/src/csharp/Grpc.Core/Version.csproj.include
index 4fffe4f644..52ab2215eb 100755
--- a/src/csharp/Grpc.Core/Version.csproj.include
+++ b/src/csharp/Grpc.Core/Version.csproj.include
@@ -1,7 +1,7 @@
 <!-- This file is generated -->
 <Project>
   <PropertyGroup>
-    <GrpcCsharpVersion>1.18.0-dev</GrpcCsharpVersion>
+    <GrpcCsharpVersion>1.19.0-dev</GrpcCsharpVersion>
     <GoogleProtobufVersion>3.6.1</GoogleProtobufVersion>
   </PropertyGroup>
 </Project>
diff --git a/src/csharp/Grpc.Core/VersionInfo.cs b/src/csharp/Grpc.Core/VersionInfo.cs
index 633880189c..8f3be310ee 100644
--- a/src/csharp/Grpc.Core/VersionInfo.cs
+++ b/src/csharp/Grpc.Core/VersionInfo.cs
@@ -33,11 +33,11 @@ namespace Grpc.Core
         /// <summary>
         /// Current <c>AssemblyFileVersion</c> of gRPC C# assemblies
         /// </summary>
-        public const string CurrentAssemblyFileVersion = "1.18.0.0";
+        public const string CurrentAssemblyFileVersion = "1.19.0.0";
 
         /// <summary>
         /// Current version of gRPC C#
         /// </summary>
-        public const string CurrentVersion = "1.18.0-dev";
+        public const string CurrentVersion = "1.19.0-dev";
     }
 }
diff --git a/src/csharp/build_packages_dotnetcli.bat b/src/csharp/build_packages_dotnetcli.bat
index 76d4f14390..fef1a43bb8 100755
--- a/src/csharp/build_packages_dotnetcli.bat
+++ b/src/csharp/build_packages_dotnetcli.bat
@@ -13,7 +13,7 @@
 @rem limitations under the License.
 
 @rem Current package versions
-set VERSION=1.18.0-dev
+set VERSION=1.19.0-dev
 
 @rem Adjust the location of nuget.exe
 set NUGET=C:\nuget\nuget.exe
diff --git a/src/csharp/build_unitypackage.bat b/src/csharp/build_unitypackage.bat
index 3334d24c11..6b66b941a8 100644
--- a/src/csharp/build_unitypackage.bat
+++ b/src/csharp/build_unitypackage.bat
@@ -13,7 +13,7 @@
 @rem limitations under the License.
 
 @rem Current package versions
-set VERSION=1.18.0-dev
+set VERSION=1.19.0-dev
 
 @rem Adjust the location of nuget.exe
 set NUGET=C:\nuget\nuget.exe
diff --git a/src/objective-c/!ProtoCompiler-gRPCPlugin.podspec b/src/objective-c/!ProtoCompiler-gRPCPlugin.podspec
index 55ca6048bc..659cfebbdc 100644
--- a/src/objective-c/!ProtoCompiler-gRPCPlugin.podspec
+++ b/src/objective-c/!ProtoCompiler-gRPCPlugin.podspec
@@ -42,7 +42,7 @@ Pod::Spec.new do |s|
   # exclamation mark ensures that other "regular" pods will be able to find it as it'll be installed
   # before them.
   s.name     = '!ProtoCompiler-gRPCPlugin'
-  v = '1.18.0-dev'
+  v = '1.19.0-dev'
   s.version  = v
   s.summary  = 'The gRPC ProtoC plugin generates Objective-C files from .proto services.'
   s.description = <<-DESC
diff --git a/src/objective-c/GRPCClient/private/version.h b/src/objective-c/GRPCClient/private/version.h
index 0be0e3c9a0..5e089fde31 100644
--- a/src/objective-c/GRPCClient/private/version.h
+++ b/src/objective-c/GRPCClient/private/version.h
@@ -22,4 +22,4 @@
 // instead. This file can be regenerated from the template by running
 // `tools/buildgen/generate_projects.sh`.
 
-#define GRPC_OBJC_VERSION_STRING @"1.18.0-dev"
+#define GRPC_OBJC_VERSION_STRING @"1.19.0-dev"
diff --git a/src/objective-c/tests/version.h b/src/objective-c/tests/version.h
index f2fd692070..54f95ad16a 100644
--- a/src/objective-c/tests/version.h
+++ b/src/objective-c/tests/version.h
@@ -22,5 +22,5 @@
 // instead. This file can be regenerated from the template by running
 // `tools/buildgen/generate_projects.sh`.
 
-#define GRPC_OBJC_VERSION_STRING @"1.18.0-dev"
+#define GRPC_OBJC_VERSION_STRING @"1.19.0-dev"
 #define GRPC_C_VERSION_STRING @"7.0.0-dev"
diff --git a/src/php/composer.json b/src/php/composer.json
index 9c298c0e85..75fab483f1 100644
--- a/src/php/composer.json
+++ b/src/php/composer.json
@@ -2,7 +2,7 @@
   "name": "grpc/grpc-dev",
   "description": "gRPC library for PHP - for Developement use only",
   "license": "Apache-2.0",
-  "version": "1.18.0",
+  "version": "1.19.0",
   "require": {
     "php": ">=5.5.0",
     "google/protobuf": "^v3.3.0"
diff --git a/src/php/ext/grpc/version.h b/src/php/ext/grpc/version.h
index 1ddf90a667..c85ee4d315 100644
--- a/src/php/ext/grpc/version.h
+++ b/src/php/ext/grpc/version.h
@@ -20,6 +20,6 @@
 #ifndef VERSION_H
 #define VERSION_H
 
-#define PHP_GRPC_VERSION "1.18.0dev"
+#define PHP_GRPC_VERSION "1.19.0dev"
 
 #endif /* VERSION_H */
diff --git a/src/python/grpcio/grpc/_grpcio_metadata.py b/src/python/grpcio/grpc/_grpcio_metadata.py
index 7a9f173947..dd9d436c3f 100644
--- a/src/python/grpcio/grpc/_grpcio_metadata.py
+++ b/src/python/grpcio/grpc/_grpcio_metadata.py
@@ -14,4 +14,4 @@
 
 # AUTO-GENERATED FROM `$REPO_ROOT/templates/src/python/grpcio/grpc/_grpcio_metadata.py.template`!!!
 
-__version__ = """1.18.0.dev0"""
+__version__ = """1.19.0.dev0"""
diff --git a/src/python/grpcio/grpc_version.py b/src/python/grpcio/grpc_version.py
index 2e91818d2c..8e2f4d30bb 100644
--- a/src/python/grpcio/grpc_version.py
+++ b/src/python/grpcio/grpc_version.py
@@ -14,4 +14,4 @@
 
 # AUTO-GENERATED FROM `$REPO_ROOT/templates/src/python/grpcio/grpc_version.py.template`!!!
 
-VERSION = '1.18.0.dev0'
+VERSION = '1.19.0.dev0'
diff --git a/src/python/grpcio_channelz/grpc_version.py b/src/python/grpcio_channelz/grpc_version.py
index 16356ea402..5f3a894a2a 100644
--- a/src/python/grpcio_channelz/grpc_version.py
+++ b/src/python/grpcio_channelz/grpc_version.py
@@ -14,4 +14,4 @@
 
 # AUTO-GENERATED FROM `$REPO_ROOT/templates/src/python/grpcio_channelz/grpc_version.py.template`!!!
 
-VERSION = '1.18.0.dev0'
+VERSION = '1.19.0.dev0'
diff --git a/src/python/grpcio_health_checking/grpc_version.py b/src/python/grpcio_health_checking/grpc_version.py
index 85fa762f7e..4c2d434066 100644
--- a/src/python/grpcio_health_checking/grpc_version.py
+++ b/src/python/grpcio_health_checking/grpc_version.py
@@ -14,4 +14,4 @@
 
 # AUTO-GENERATED FROM `$REPO_ROOT/templates/src/python/grpcio_health_checking/grpc_version.py.template`!!!
 
-VERSION = '1.18.0.dev0'
+VERSION = '1.19.0.dev0'
diff --git a/src/python/grpcio_reflection/grpc_version.py b/src/python/grpcio_reflection/grpc_version.py
index e62ab169a2..6b88b2dfc5 100644
--- a/src/python/grpcio_reflection/grpc_version.py
+++ b/src/python/grpcio_reflection/grpc_version.py
@@ -14,4 +14,4 @@
 
 # AUTO-GENERATED FROM `$REPO_ROOT/templates/src/python/grpcio_reflection/grpc_version.py.template`!!!
 
-VERSION = '1.18.0.dev0'
+VERSION = '1.19.0.dev0'
diff --git a/src/python/grpcio_status/grpc_version.py b/src/python/grpcio_status/grpc_version.py
index e009843b94..2e58eb3b26 100644
--- a/src/python/grpcio_status/grpc_version.py
+++ b/src/python/grpcio_status/grpc_version.py
@@ -14,4 +14,4 @@
 
 # AUTO-GENERATED FROM `$REPO_ROOT/templates/src/python/grpcio_status/grpc_version.py.template`!!!
 
-VERSION = '1.18.0.dev0'
+VERSION = '1.19.0.dev0'
diff --git a/src/python/grpcio_testing/grpc_version.py b/src/python/grpcio_testing/grpc_version.py
index 7b4c1695fa..d4c5d94ecb 100644
--- a/src/python/grpcio_testing/grpc_version.py
+++ b/src/python/grpcio_testing/grpc_version.py
@@ -14,4 +14,4 @@
 
 # AUTO-GENERATED FROM `$REPO_ROOT/templates/src/python/grpcio_testing/grpc_version.py.template`!!!
 
-VERSION = '1.18.0.dev0'
+VERSION = '1.19.0.dev0'
diff --git a/src/python/grpcio_tests/grpc_version.py b/src/python/grpcio_tests/grpc_version.py
index 2fcd1ad617..e1645ab1b8 100644
--- a/src/python/grpcio_tests/grpc_version.py
+++ b/src/python/grpcio_tests/grpc_version.py
@@ -14,4 +14,4 @@
 
 # AUTO-GENERATED FROM `$REPO_ROOT/templates/src/python/grpcio_tests/grpc_version.py.template`!!!
 
-VERSION = '1.18.0.dev0'
+VERSION = '1.19.0.dev0'
diff --git a/src/python/grpcio_tests/tests/unit/_cython/_fork_test.py b/src/python/grpcio_tests/tests/unit/_cython/_fork_test.py
index aeb02458a7..5a5dedd5f2 100644
--- a/src/python/grpcio_tests/tests/unit/_cython/_fork_test.py
+++ b/src/python/grpcio_tests/tests/unit/_cython/_fork_test.py
@@ -27,6 +27,7 @@ def _get_number_active_threads():
 class ForkPosixTester(unittest.TestCase):
 
     def setUp(self):
+        self._saved_fork_support_flag = cygrpc._GRPC_ENABLE_FORK_SUPPORT
         cygrpc._GRPC_ENABLE_FORK_SUPPORT = True
 
     def testForkManagedThread(self):
@@ -50,6 +51,9 @@ class ForkPosixTester(unittest.TestCase):
         thread.join()
         self.assertEqual(0, _get_number_active_threads())
 
+    def tearDown(self):
+        cygrpc._GRPC_ENABLE_FORK_SUPPORT = self._saved_fork_support_flag
+
 
 @unittest.skipUnless(os.name == 'nt', 'Windows-specific tests')
 class ForkWindowsTester(unittest.TestCase):
diff --git a/src/python/grpcio_tests/tests/unit/_logging_test.py b/src/python/grpcio_tests/tests/unit/_logging_test.py
index 631b9de9db..8ff127f506 100644
--- a/src/python/grpcio_tests/tests/unit/_logging_test.py
+++ b/src/python/grpcio_tests/tests/unit/_logging_test.py
@@ -14,66 +14,86 @@
 """Test of gRPC Python's interaction with the python logging module"""
 
 import unittest
-import six
-from six.moves import reload_module
 import logging
 import grpc
-import functools
+import subprocess
 import sys
 
+INTERPRETER = sys.executable
 
-def patch_stderr(f):
 
-    @functools.wraps(f)
-    def _impl(*args, **kwargs):
-        old_stderr = sys.stderr
-        sys.stderr = six.StringIO()
-        try:
-            f(*args, **kwargs)
-        finally:
-            sys.stderr = old_stderr
+class LoggingTest(unittest.TestCase):
 
-    return _impl
+    def test_logger_not_occupied(self):
+        script = """if True:
+            import logging
 
+            import grpc
 
-def isolated_logging(f):
+            if len(logging.getLogger().handlers) != 0:
+                raise Exception('expected 0 logging handlers')
 
-    @functools.wraps(f)
-    def _impl(*args, **kwargs):
-        reload_module(logging)
-        reload_module(grpc)
-        try:
-            f(*args, **kwargs)
-        finally:
-            reload_module(logging)
+        """
+        self._verifyScriptSucceeds(script)
 
-    return _impl
+    def test_handler_found(self):
+        script = """if True:
+            import logging
 
+            import grpc
+        """
+        out, err = self._verifyScriptSucceeds(script)
+        self.assertEqual(0, len(err), 'unexpected output to stderr')
 
-class LoggingTest(unittest.TestCase):
+    def test_can_configure_logger(self):
+        script = """if True:
+            import logging
+            import six
 
-    @isolated_logging
-    def test_logger_not_occupied(self):
-        self.assertEqual(0, len(logging.getLogger().handlers))
+            import grpc
 
-    @patch_stderr
-    @isolated_logging
-    def test_handler_found(self):
-        self.assertEqual(0, len(sys.stderr.getvalue()))
 
-    @isolated_logging
-    def test_can_configure_logger(self):
-        intended_stream = six.StringIO()
-        logging.basicConfig(stream=intended_stream)
-        self.assertEqual(1, len(logging.getLogger().handlers))
-        self.assertIs(logging.getLogger().handlers[0].stream, intended_stream)
+            intended_stream = six.StringIO()
+            logging.basicConfig(stream=intended_stream)
+
+            if len(logging.getLogger().handlers) != 1:
+                raise Exception('expected 1 logging handler')
+
+            if logging.getLogger().handlers[0].stream is not intended_stream:
+                raise Exception('wrong handler stream')
+
+        """
+        self._verifyScriptSucceeds(script)
 
-    @isolated_logging
     def test_grpc_logger(self):
-        self.assertIn("grpc", logging.Logger.manager.loggerDict)
-        root_logger = logging.getLogger("grpc")
-        self.assertEqual(1, len(root_logger.handlers))
-        self.assertIsInstance(root_logger.handlers[0], logging.NullHandler)
+        script = """if True:
+            import logging
+
+            import grpc
+
+            if "grpc" not in logging.Logger.manager.loggerDict:
+                raise Exception('grpc logger not found')
+
+            root_logger = logging.getLogger("grpc")
+            if len(root_logger.handlers) != 1:
+                raise Exception('expected 1 root logger handler')
+            if not isinstance(root_logger.handlers[0], logging.NullHandler):
+                raise Exception('expected logging.NullHandler')
+
+        """
+        self._verifyScriptSucceeds(script)
+
+    def _verifyScriptSucceeds(self, script):
+        process = subprocess.Popen(
+            [INTERPRETER, '-c', script],
+            stdout=subprocess.PIPE,
+            stderr=subprocess.PIPE)
+        out, err = process.communicate()
+        self.assertEqual(
+            0, process.returncode,
+            'process failed with exit code %d (stdout: %s, stderr: %s)' %
+            (process.returncode, out, err))
+        return out, err
 
 
 if __name__ == '__main__':
diff --git a/src/ruby/lib/grpc/version.rb b/src/ruby/lib/grpc/version.rb
index a4ed052d85..3b7f62d9f5 100644
--- a/src/ruby/lib/grpc/version.rb
+++ b/src/ruby/lib/grpc/version.rb
@@ -14,5 +14,5 @@
 
 # GRPC contains the General RPC module.
 module GRPC
-  VERSION = '1.18.0.dev'
+  VERSION = '1.19.0.dev'
 end
diff --git a/src/ruby/tools/version.rb b/src/ruby/tools/version.rb
index 389fb70684..2ad685a7eb 100644
--- a/src/ruby/tools/version.rb
+++ b/src/ruby/tools/version.rb
@@ -14,6 +14,6 @@
 
 module GRPC
   module Tools
-    VERSION = '1.18.0.dev'
+    VERSION = '1.19.0.dev'
   end
 end
diff --git a/test/cpp/end2end/client_interceptors_end2end_test.cc b/test/cpp/end2end/client_interceptors_end2end_test.cc
index ea72c1eda8..177922f457 100644
--- a/test/cpp/end2end/client_interceptors_end2end_test.cc
+++ b/test/cpp/end2end/client_interceptors_end2end_test.cc
@@ -270,6 +270,235 @@ class HijackingInterceptorMakesAnotherCallFactory
   }
 };
 
+class BidiStreamingRpcHijackingInterceptor : public experimental::Interceptor {
+ public:
+  BidiStreamingRpcHijackingInterceptor(experimental::ClientRpcInfo* info) {
+    info_ = info;
+  }
+
+  virtual void Intercept(experimental::InterceptorBatchMethods* methods) {
+    bool hijack = false;
+    if (methods->QueryInterceptionHookPoint(
+            experimental::InterceptionHookPoints::PRE_SEND_INITIAL_METADATA)) {
+      CheckMetadata(*methods->GetSendInitialMetadata(), "testkey", "testvalue");
+      hijack = true;
+    }
+    if (methods->QueryInterceptionHookPoint(
+            experimental::InterceptionHookPoints::PRE_SEND_MESSAGE)) {
+      EchoRequest req;
+      auto* buffer = methods->GetSerializedSendMessage();
+      auto copied_buffer = *buffer;
+      EXPECT_TRUE(
+          SerializationTraits<EchoRequest>::Deserialize(&copied_buffer, &req)
+              .ok());
+      EXPECT_EQ(req.message().find("Hello"), 0u);
+      msg = req.message();
+    }
+    if (methods->QueryInterceptionHookPoint(
+            experimental::InterceptionHookPoints::PRE_SEND_CLOSE)) {
+      // Got nothing to do here for now
+    }
+    if (methods->QueryInterceptionHookPoint(
+            experimental::InterceptionHookPoints::POST_RECV_STATUS)) {
+      CheckMetadata(*methods->GetRecvTrailingMetadata(), "testkey",
+                    "testvalue");
+      auto* status = methods->GetRecvStatus();
+      EXPECT_EQ(status->ok(), true);
+    }
+    if (methods->QueryInterceptionHookPoint(
+            experimental::InterceptionHookPoints::PRE_RECV_MESSAGE)) {
+      EchoResponse* resp =
+          static_cast<EchoResponse*>(methods->GetRecvMessage());
+      resp->set_message(msg);
+    }
+    if (methods->QueryInterceptionHookPoint(
+            experimental::InterceptionHookPoints::POST_RECV_MESSAGE)) {
+      EXPECT_EQ(static_cast<EchoResponse*>(methods->GetRecvMessage())
+                    ->message()
+                    .find("Hello"),
+                0u);
+    }
+    if (methods->QueryInterceptionHookPoint(
+            experimental::InterceptionHookPoints::PRE_RECV_STATUS)) {
+      auto* map = methods->GetRecvTrailingMetadata();
+      // insert the metadata that we want
+      EXPECT_EQ(map->size(), static_cast<unsigned>(0));
+      map->insert(std::make_pair("testkey", "testvalue"));
+      auto* status = methods->GetRecvStatus();
+      *status = Status(StatusCode::OK, "");
+    }
+    if (hijack) {
+      methods->Hijack();
+    } else {
+      methods->Proceed();
+    }
+  }
+
+ private:
+  experimental::ClientRpcInfo* info_;
+  grpc::string msg;
+};
+
+class ClientStreamingRpcHijackingInterceptor
+    : public experimental::Interceptor {
+ public:
+  ClientStreamingRpcHijackingInterceptor(experimental::ClientRpcInfo* info) {
+    info_ = info;
+  }
+  virtual void Intercept(experimental::InterceptorBatchMethods* methods) {
+    bool hijack = false;
+    if (methods->QueryInterceptionHookPoint(
+            experimental::InterceptionHookPoints::PRE_SEND_INITIAL_METADATA)) {
+      hijack = true;
+    }
+    if (methods->QueryInterceptionHookPoint(
+            experimental::InterceptionHookPoints::PRE_SEND_MESSAGE)) {
+      if (++count_ > 10) {
+        methods->FailHijackedSendMessage();
+      }
+    }
+    if (methods->QueryInterceptionHookPoint(
+            experimental::InterceptionHookPoints::POST_SEND_MESSAGE)) {
+      EXPECT_FALSE(got_failed_send_);
+      got_failed_send_ = !methods->GetSendMessageStatus();
+    }
+    if (methods->QueryInterceptionHookPoint(
+            experimental::InterceptionHookPoints::PRE_RECV_STATUS)) {
+      auto* status = methods->GetRecvStatus();
+      *status = Status(StatusCode::UNAVAILABLE, "Done sending 10 messages");
+    }
+    if (hijack) {
+      methods->Hijack();
+    } else {
+      methods->Proceed();
+    }
+  }
+
+  static bool GotFailedSend() { return got_failed_send_; }
+
+ private:
+  experimental::ClientRpcInfo* info_;
+  int count_ = 0;
+  static bool got_failed_send_;
+};
+
+bool ClientStreamingRpcHijackingInterceptor::got_failed_send_ = false;
+
+class ClientStreamingRpcHijackingInterceptorFactory
+    : public experimental::ClientInterceptorFactoryInterface {
+ public:
+  virtual experimental::Interceptor* CreateClientInterceptor(
+      experimental::ClientRpcInfo* info) override {
+    return new ClientStreamingRpcHijackingInterceptor(info);
+  }
+};
+
+class ServerStreamingRpcHijackingInterceptor
+    : public experimental::Interceptor {
+ public:
+  ServerStreamingRpcHijackingInterceptor(experimental::ClientRpcInfo* info) {
+    info_ = info;
+  }
+
+  virtual void Intercept(experimental::InterceptorBatchMethods* methods) {
+    bool hijack = false;
+    if (methods->QueryInterceptionHookPoint(
+            experimental::InterceptionHookPoints::PRE_SEND_INITIAL_METADATA)) {
+      auto* map = methods->GetSendInitialMetadata();
+      // Check that we can see the test metadata
+      ASSERT_EQ(map->size(), static_cast<unsigned>(1));
+      auto iterator = map->begin();
+      EXPECT_EQ("testkey", iterator->first);
+      EXPECT_EQ("testvalue", iterator->second);
+      hijack = true;
+    }
+    if (methods->QueryInterceptionHookPoint(
+            experimental::InterceptionHookPoints::PRE_SEND_MESSAGE)) {
+      EchoRequest req;
+      auto* buffer = methods->GetSerializedSendMessage();
+      auto copied_buffer = *buffer;
+      EXPECT_TRUE(
+          SerializationTraits<EchoRequest>::Deserialize(&copied_buffer, &req)
+              .ok());
+      EXPECT_EQ(req.message(), "Hello");
+    }
+    if (methods->QueryInterceptionHookPoint(
+            experimental::InterceptionHookPoints::PRE_SEND_CLOSE)) {
+      // Got nothing to do here for now
+    }
+    if (methods->QueryInterceptionHookPoint(
+            experimental::InterceptionHookPoints::POST_RECV_STATUS)) {
+      auto* map = methods->GetRecvTrailingMetadata();
+      bool found = false;
+      // Check that we received the metadata as an echo
+      for (const auto& pair : *map) {
+        found = pair.first.starts_with("testkey") &&
+                pair.second.starts_with("testvalue");
+        if (found) break;
+      }
+      EXPECT_EQ(found, true);
+      auto* status = methods->GetRecvStatus();
+      EXPECT_EQ(status->ok(), true);
+    }
+    if (methods->QueryInterceptionHookPoint(
+            experimental::InterceptionHookPoints::PRE_RECV_MESSAGE)) {
+      if (++count_ > 10) {
+        methods->FailHijackedRecvMessage();
+      }
+      EchoResponse* resp =
+          static_cast<EchoResponse*>(methods->GetRecvMessage());
+      resp->set_message("Hello");
+    }
+    if (methods->QueryInterceptionHookPoint(
+            experimental::InterceptionHookPoints::POST_RECV_MESSAGE)) {
+      // Only the last message will be a failure
+      EXPECT_FALSE(got_failed_message_);
+      got_failed_message_ = methods->GetRecvMessage() == nullptr;
+    }
+    if (methods->QueryInterceptionHookPoint(
+            experimental::InterceptionHookPoints::PRE_RECV_STATUS)) {
+      auto* map = methods->GetRecvTrailingMetadata();
+      // insert the metadata that we want
+      EXPECT_EQ(map->size(), static_cast<unsigned>(0));
+      map->insert(std::make_pair("testkey", "testvalue"));
+      auto* status = methods->GetRecvStatus();
+      *status = Status(StatusCode::OK, "");
+    }
+    if (hijack) {
+      methods->Hijack();
+    } else {
+      methods->Proceed();
+    }
+  }
+
+  static bool GotFailedMessage() { return got_failed_message_; }
+
+ private:
+  experimental::ClientRpcInfo* info_;
+  static bool got_failed_message_;
+  int count_ = 0;
+};
+
+bool ServerStreamingRpcHijackingInterceptor::got_failed_message_ = false;
+
+class ServerStreamingRpcHijackingInterceptorFactory
+    : public experimental::ClientInterceptorFactoryInterface {
+ public:
+  virtual experimental::Interceptor* CreateClientInterceptor(
+      experimental::ClientRpcInfo* info) override {
+    return new ServerStreamingRpcHijackingInterceptor(info);
+  }
+};
+
+class BidiStreamingRpcHijackingInterceptorFactory
+    : public experimental::ClientInterceptorFactoryInterface {
+ public:
+  virtual experimental::Interceptor* CreateClientInterceptor(
+      experimental::ClientRpcInfo* info) override {
+    return new BidiStreamingRpcHijackingInterceptor(info);
+  }
+};
+
 class LoggingInterceptor : public experimental::Interceptor {
  public:
   LoggingInterceptor(experimental::ClientRpcInfo* info) { info_ = info; }
@@ -550,6 +779,62 @@ TEST_F(ClientInterceptorsStreamingEnd2endTest, ServerStreamingTest) {
   EXPECT_EQ(DummyInterceptor::GetNumTimesRun(), 20);
 }
 
+TEST_F(ClientInterceptorsStreamingEnd2endTest, ClientStreamingHijackingTest) {
+  ChannelArguments args;
+  std::vector<std::unique_ptr<experimental::ClientInterceptorFactoryInterface>>
+      creators;
+  creators.push_back(
+      std::unique_ptr<ClientStreamingRpcHijackingInterceptorFactory>(
+          new ClientStreamingRpcHijackingInterceptorFactory()));
+  auto channel = experimental::CreateCustomChannelWithInterceptors(
+      server_address_, InsecureChannelCredentials(), args, std::move(creators));
+
+  auto stub = grpc::testing::EchoTestService::NewStub(channel);
+  ClientContext ctx;
+  EchoRequest req;
+  EchoResponse resp;
+  req.mutable_param()->set_echo_metadata(true);
+  req.set_message("Hello");
+  string expected_resp = "";
+  auto writer = stub->RequestStream(&ctx, &resp);
+  for (int i = 0; i < 10; i++) {
+    EXPECT_TRUE(writer->Write(req));
+    expected_resp += "Hello";
+  }
+  // The interceptor will reject the 11th message
+  writer->Write(req);
+  Status s = writer->Finish();
+  EXPECT_EQ(s.ok(), false);
+  EXPECT_TRUE(ClientStreamingRpcHijackingInterceptor::GotFailedSend());
+}
+
+TEST_F(ClientInterceptorsStreamingEnd2endTest, ServerStreamingHijackingTest) {
+  ChannelArguments args;
+  DummyInterceptor::Reset();
+  std::vector<std::unique_ptr<experimental::ClientInterceptorFactoryInterface>>
+      creators;
+  creators.push_back(
+      std::unique_ptr<ServerStreamingRpcHijackingInterceptorFactory>(
+          new ServerStreamingRpcHijackingInterceptorFactory()));
+  auto channel = experimental::CreateCustomChannelWithInterceptors(
+      server_address_, InsecureChannelCredentials(), args, std::move(creators));
+  MakeServerStreamingCall(channel);
+  EXPECT_TRUE(ServerStreamingRpcHijackingInterceptor::GotFailedMessage());
+}
+
+TEST_F(ClientInterceptorsStreamingEnd2endTest, BidiStreamingHijackingTest) {
+  ChannelArguments args;
+  DummyInterceptor::Reset();
+  std::vector<std::unique_ptr<experimental::ClientInterceptorFactoryInterface>>
+      creators;
+  creators.push_back(
+      std::unique_ptr<BidiStreamingRpcHijackingInterceptorFactory>(
+          new BidiStreamingRpcHijackingInterceptorFactory()));
+  auto channel = experimental::CreateCustomChannelWithInterceptors(
+      server_address_, InsecureChannelCredentials(), args, std::move(creators));
+  MakeBidiStreamingCall(channel);
+}
+
 TEST_F(ClientInterceptorsStreamingEnd2endTest, BidiStreamingTest) {
   ChannelArguments args;
   DummyInterceptor::Reset();
diff --git a/test/cpp/end2end/interceptors_util.cc b/test/cpp/end2end/interceptors_util.cc
index e0ad7d1526..900f02b5f3 100644
--- a/test/cpp/end2end/interceptors_util.cc
+++ b/test/cpp/end2end/interceptors_util.cc
@@ -132,6 +132,16 @@ bool CheckMetadata(const std::multimap<grpc::string_ref, grpc::string_ref>& map,
   return false;
 }
 
+bool CheckMetadata(const std::multimap<grpc::string, grpc::string>& map,
+                   const string& key, const string& value) {
+  for (const auto& pair : map) {
+    if (pair.first == key && pair.second == value) {
+      return true;
+    }
+  }
+  return false;
+}
+
 std::vector<std::unique_ptr<experimental::ClientInterceptorFactoryInterface>>
 CreateDummyClientInterceptors() {
   std::vector<std::unique_ptr<experimental::ClientInterceptorFactoryInterface>>
diff --git a/test/cpp/end2end/interceptors_util.h b/test/cpp/end2end/interceptors_util.h
index 659e613d2e..419845e5f6 100644
--- a/test/cpp/end2end/interceptors_util.h
+++ b/test/cpp/end2end/interceptors_util.h
@@ -165,6 +165,9 @@ void MakeCallbackCall(const std::shared_ptr<Channel>& channel);
 bool CheckMetadata(const std::multimap<grpc::string_ref, grpc::string_ref>& map,
                    const string& key, const string& value);
 
+bool CheckMetadata(const std::multimap<grpc::string, grpc::string>& map,
+                   const string& key, const string& value);
+
 std::vector<std::unique_ptr<experimental::ClientInterceptorFactoryInterface>>
 CreateDummyClientInterceptors();
 
diff --git a/test/cpp/qps/client.h b/test/cpp/qps/client.h
index 73f91eed2d..ceb5cdd710 100644
--- a/test/cpp/qps/client.h
+++ b/test/cpp/qps/client.h
@@ -236,58 +236,7 @@ class Client {
     return 0;
   }
 
- protected:
-  bool closed_loop_;
-  gpr_atm thread_pool_done_;
-  double median_latency_collection_interval_seconds_;  // In seconds
-
-  void StartThreads(size_t num_threads) {
-    gpr_atm_rel_store(&thread_pool_done_, static_cast<gpr_atm>(false));
-    threads_remaining_ = num_threads;
-    for (size_t i = 0; i < num_threads; i++) {
-      threads_.emplace_back(new Thread(this, i));
-    }
-  }
-
-  void EndThreads() {
-    MaybeStartRequests();
-    threads_.clear();
-  }
-
-  virtual void DestroyMultithreading() = 0;
-
-  void SetupLoadTest(const ClientConfig& config, size_t num_threads) {
-    // Set up the load distribution based on the number of threads
-    const auto& load = config.load_params();
-
-    std::unique_ptr<RandomDistInterface> random_dist;
-    switch (load.load_case()) {
-      case LoadParams::kClosedLoop:
-        // Closed-loop doesn't use random dist at all
-        break;
-      case LoadParams::kPoisson:
-        random_dist.reset(
-            new ExpDist(load.poisson().offered_load() / num_threads));
-        break;
-      default:
-        GPR_ASSERT(false);
-    }
-
-    // Set closed_loop_ based on whether or not random_dist is set
-    if (!random_dist) {
-      closed_loop_ = true;
-    } else {
-      closed_loop_ = false;
-      // set up interarrival timer according to random dist
-      interarrival_timer_.init(*random_dist, num_threads);
-      const auto now = gpr_now(GPR_CLOCK_MONOTONIC);
-      for (size_t i = 0; i < num_threads; i++) {
-        next_time_.push_back(gpr_time_add(
-            now,
-            gpr_time_from_nanos(interarrival_timer_.next(i), GPR_TIMESPAN)));
-      }
-    }
-  }
+  bool IsClosedLoop() { return closed_loop_; }
 
   gpr_timespec NextIssueTime(int thread_idx) {
     const gpr_timespec result = next_time_[thread_idx];
@@ -297,9 +246,9 @@ class Client {
                                          GPR_TIMESPAN));
     return result;
   }
-  std::function<gpr_timespec()> NextIssuer(int thread_idx) {
-    return closed_loop_ ? std::function<gpr_timespec()>()
-                        : std::bind(&Client::NextIssueTime, this, thread_idx);
+
+  bool ThreadCompleted() {
+    return static_cast<bool>(gpr_atm_acq_load(&thread_pool_done_));
   }
 
   class Thread {
@@ -380,8 +329,62 @@ class Client {
     double interval_start_time_;
   };
 
-  bool ThreadCompleted() {
-    return static_cast<bool>(gpr_atm_acq_load(&thread_pool_done_));
+ protected:
+  bool closed_loop_;
+  gpr_atm thread_pool_done_;
+  double median_latency_collection_interval_seconds_;  // In seconds
+
+  void StartThreads(size_t num_threads) {
+    gpr_atm_rel_store(&thread_pool_done_, static_cast<gpr_atm>(false));
+    threads_remaining_ = num_threads;
+    for (size_t i = 0; i < num_threads; i++) {
+      threads_.emplace_back(new Thread(this, i));
+    }
+  }
+
+  void EndThreads() {
+    MaybeStartRequests();
+    threads_.clear();
+  }
+
+  virtual void DestroyMultithreading() = 0;
+
+  void SetupLoadTest(const ClientConfig& config, size_t num_threads) {
+    // Set up the load distribution based on the number of threads
+    const auto& load = config.load_params();
+
+    std::unique_ptr<RandomDistInterface> random_dist;
+    switch (load.load_case()) {
+      case LoadParams::kClosedLoop:
+        // Closed-loop doesn't use random dist at all
+        break;
+      case LoadParams::kPoisson:
+        random_dist.reset(
+            new ExpDist(load.poisson().offered_load() / num_threads));
+        break;
+      default:
+        GPR_ASSERT(false);
+    }
+
+    // Set closed_loop_ based on whether or not random_dist is set
+    if (!random_dist) {
+      closed_loop_ = true;
+    } else {
+      closed_loop_ = false;
+      // set up interarrival timer according to random dist
+      interarrival_timer_.init(*random_dist, num_threads);
+      const auto now = gpr_now(GPR_CLOCK_MONOTONIC);
+      for (size_t i = 0; i < num_threads; i++) {
+        next_time_.push_back(gpr_time_add(
+            now,
+            gpr_time_from_nanos(interarrival_timer_.next(i), GPR_TIMESPAN)));
+      }
+    }
+  }
+
+  std::function<gpr_timespec()> NextIssuer(int thread_idx) {
+    return closed_loop_ ? std::function<gpr_timespec()>()
+                        : std::bind(&Client::NextIssueTime, this, thread_idx);
   }
 
   virtual void ThreadFunc(size_t thread_idx, Client::Thread* t) = 0;
@@ -436,6 +439,7 @@ class ClientImpl : public Client {
                                                  config.payload_config());
   }
   virtual ~ClientImpl() {}
+  const RequestType* request() { return &request_; }
 
   void WaitForChannelsToConnect() {
     int connect_deadline_seconds = 10;
diff --git a/test/cpp/qps/client_callback.cc b/test/cpp/qps/client_callback.cc
index 87889e36dc..4a06325f2b 100644
--- a/test/cpp/qps/client_callback.cc
+++ b/test/cpp/qps/client_callback.cc
@@ -66,13 +66,35 @@ class CallbackClient
             config, BenchmarkStubCreator) {
     num_threads_ = NumThreads(config);
     rpcs_done_ = 0;
-    SetupLoadTest(config, num_threads_);
+
+    //  Don't divide the fixed load among threads as the user threads
+    //  only bootstrap the RPCs
+    SetupLoadTest(config, 1);
     total_outstanding_rpcs_ =
         config.client_channels() * config.outstanding_rpcs_per_channel();
   }
 
   virtual ~CallbackClient() {}
 
+  /**
+   * The main thread of the benchmark will be waiting on DestroyMultithreading.
+   * Increment the rpcs_done_ variable to signify that the Callback RPC
+   * after thread completion is done. When the last outstanding rpc increments
+   * the counter it should also signal the main thread's conditional variable.
+   */
+  void NotifyMainThreadOfThreadCompletion() {
+    std::lock_guard<std::mutex> l(shutdown_mu_);
+    rpcs_done_++;
+    if (rpcs_done_ == total_outstanding_rpcs_) {
+      shutdown_cv_.notify_one();
+    }
+  }
+
+  gpr_timespec NextRPCIssueTime() {
+    std::lock_guard<std::mutex> l(next_issue_time_mu_);
+    return Client::NextIssueTime(0);
+  }
+
  protected:
   size_t num_threads_;
   size_t total_outstanding_rpcs_;
@@ -93,24 +115,9 @@ class CallbackClient
     ThreadFuncImpl(t, thread_idx);
   }
 
-  virtual void ScheduleRpc(Thread* t, size_t thread_idx,
-                           size_t ctx_vector_idx) = 0;
-
-  /**
-   * The main thread of the benchmark will be waiting on DestroyMultithreading.
-   * Increment the rpcs_done_ variable to signify that the Callback RPC
-   * after thread completion is done. When the last outstanding rpc increments
-   * the counter it should also signal the main thread's conditional variable.
-   */
-  void NotifyMainThreadOfThreadCompletion() {
-    std::lock_guard<std::mutex> l(shutdown_mu_);
-    rpcs_done_++;
-    if (rpcs_done_ == total_outstanding_rpcs_) {
-      shutdown_cv_.notify_one();
-    }
-  }
-
  private:
+  std::mutex next_issue_time_mu_;  // Used by next issue time
+
   int NumThreads(const ClientConfig& config) {
     int num_threads = config.async_client_threads();
     if (num_threads <= 0) {  // Use dynamic sizing
@@ -149,7 +156,7 @@ class CallbackUnaryClient final : public CallbackClient {
   bool ThreadFuncImpl(Thread* t, size_t thread_idx) override {
     for (size_t vector_idx = thread_idx; vector_idx < total_outstanding_rpcs_;
          vector_idx += num_threads_) {
-      ScheduleRpc(t, thread_idx, vector_idx);
+      ScheduleRpc(t, vector_idx);
     }
     return true;
   }
@@ -157,26 +164,26 @@ class CallbackUnaryClient final : public CallbackClient {
   void InitThreadFuncImpl(size_t thread_idx) override { return; }
 
  private:
-  void ScheduleRpc(Thread* t, size_t thread_idx, size_t vector_idx) override {
+  void ScheduleRpc(Thread* t, size_t vector_idx) {
     if (!closed_loop_) {
-      gpr_timespec next_issue_time = NextIssueTime(thread_idx);
+      gpr_timespec next_issue_time = NextRPCIssueTime();
       // Start an alarm callback to run the internal callback after
       // next_issue_time
       ctx_[vector_idx]->alarm_.experimental().Set(
-          next_issue_time, [this, t, thread_idx, vector_idx](bool ok) {
-            IssueUnaryCallbackRpc(t, thread_idx, vector_idx);
+          next_issue_time, [this, t, vector_idx](bool ok) {
+            IssueUnaryCallbackRpc(t, vector_idx);
           });
     } else {
-      IssueUnaryCallbackRpc(t, thread_idx, vector_idx);
+      IssueUnaryCallbackRpc(t, vector_idx);
     }
   }
 
-  void IssueUnaryCallbackRpc(Thread* t, size_t thread_idx, size_t vector_idx) {
+  void IssueUnaryCallbackRpc(Thread* t, size_t vector_idx) {
     GPR_TIMER_SCOPE("CallbackUnaryClient::ThreadFunc", 0);
     double start = UsageTimer::Now();
     ctx_[vector_idx]->stub_->experimental_async()->UnaryCall(
         (&ctx_[vector_idx]->context_), &request_, &ctx_[vector_idx]->response_,
-        [this, t, thread_idx, start, vector_idx](grpc::Status s) {
+        [this, t, start, vector_idx](grpc::Status s) {
           // Update Histogram with data from the callback run
           HistogramEntry entry;
           if (s.ok()) {
@@ -193,17 +200,157 @@ class CallbackUnaryClient final : public CallbackClient {
             ctx_[vector_idx].reset(
                 new CallbackClientRpcContext(ctx_[vector_idx]->stub_));
             // Schedule a new RPC
-            ScheduleRpc(t, thread_idx, vector_idx);
+            ScheduleRpc(t, vector_idx);
           }
         });
   }
 };
 
+class CallbackStreamingClient : public CallbackClient {
+ public:
+  CallbackStreamingClient(const ClientConfig& config)
+      : CallbackClient(config),
+        messages_per_stream_(config.messages_per_stream()) {
+    for (int ch = 0; ch < config.client_channels(); ch++) {
+      for (int i = 0; i < config.outstanding_rpcs_per_channel(); i++) {
+        ctx_.emplace_back(
+            new CallbackClientRpcContext(channels_[ch].get_stub()));
+      }
+    }
+    StartThreads(num_threads_);
+  }
+  ~CallbackStreamingClient() {}
+
+  void AddHistogramEntry(double start_, bool ok, Thread* thread_ptr) {
+    // Update Histogram with data from the callback run
+    HistogramEntry entry;
+    if (ok) {
+      entry.set_value((UsageTimer::Now() - start_) * 1e9);
+    }
+    thread_ptr->UpdateHistogram(&entry);
+  }
+
+  int messages_per_stream() { return messages_per_stream_; }
+
+ protected:
+  const int messages_per_stream_;
+};
+
+class CallbackStreamingPingPongClient : public CallbackStreamingClient {
+ public:
+  CallbackStreamingPingPongClient(const ClientConfig& config)
+      : CallbackStreamingClient(config) {}
+  ~CallbackStreamingPingPongClient() {}
+};
+
+class CallbackStreamingPingPongReactor final
+    : public grpc::experimental::ClientBidiReactor<SimpleRequest,
+                                                   SimpleResponse> {
+ public:
+  CallbackStreamingPingPongReactor(
+      CallbackStreamingPingPongClient* client,
+      std::unique_ptr<CallbackClientRpcContext> ctx)
+      : client_(client), ctx_(std::move(ctx)), messages_issued_(0) {}
+
+  void StartNewRpc() {
+    if (client_->ThreadCompleted()) return;
+    start_ = UsageTimer::Now();
+    ctx_->stub_->experimental_async()->StreamingCall(&(ctx_->context_), this);
+    StartWrite(client_->request());
+    StartCall();
+  }
+
+  void OnWriteDone(bool ok) override {
+    if (!ok || client_->ThreadCompleted()) {
+      if (!ok) gpr_log(GPR_ERROR, "Error writing RPC");
+      StartWritesDone();
+      return;
+    }
+    StartRead(&ctx_->response_);
+  }
+
+  void OnReadDone(bool ok) override {
+    client_->AddHistogramEntry(start_, ok, thread_ptr_);
+
+    if (client_->ThreadCompleted() || !ok ||
+        (client_->messages_per_stream() != 0 &&
+         ++messages_issued_ >= client_->messages_per_stream())) {
+      if (!ok) {
+        gpr_log(GPR_ERROR, "Error reading RPC");
+      }
+      StartWritesDone();
+      return;
+    }
+    StartWrite(client_->request());
+  }
+
+  void OnDone(const Status& s) override {
+    if (client_->ThreadCompleted() || !s.ok()) {
+      client_->NotifyMainThreadOfThreadCompletion();
+      return;
+    }
+    ctx_.reset(new CallbackClientRpcContext(ctx_->stub_));
+    ScheduleRpc();
+  }
+
+  void ScheduleRpc() {
+    if (client_->ThreadCompleted()) return;
+
+    if (!client_->IsClosedLoop()) {
+      gpr_timespec next_issue_time = client_->NextRPCIssueTime();
+      // Start an alarm callback to run the internal callback after
+      // next_issue_time
+      ctx_->alarm_.experimental().Set(next_issue_time,
+                                      [this](bool ok) { StartNewRpc(); });
+    } else {
+      StartNewRpc();
+    }
+  }
+
+  void set_thread_ptr(Client::Thread* ptr) { thread_ptr_ = ptr; }
+
+  CallbackStreamingPingPongClient* client_;
+  std::unique_ptr<CallbackClientRpcContext> ctx_;
+  Client::Thread* thread_ptr_;  // Needed to update histogram entries
+  double start_;                // Track message start time
+  int messages_issued_;         // Messages issued by this stream
+};
+
+class CallbackStreamingPingPongClientImpl final
+    : public CallbackStreamingPingPongClient {
+ public:
+  CallbackStreamingPingPongClientImpl(const ClientConfig& config)
+      : CallbackStreamingPingPongClient(config) {
+    for (size_t i = 0; i < total_outstanding_rpcs_; i++)
+      reactor_.emplace_back(
+          new CallbackStreamingPingPongReactor(this, std::move(ctx_[i])));
+  }
+  ~CallbackStreamingPingPongClientImpl() {}
+
+  bool ThreadFuncImpl(Client::Thread* t, size_t thread_idx) override {
+    for (size_t vector_idx = thread_idx; vector_idx < total_outstanding_rpcs_;
+         vector_idx += num_threads_) {
+      reactor_[vector_idx]->set_thread_ptr(t);
+      reactor_[vector_idx]->ScheduleRpc();
+    }
+    return true;
+  }
+
+  void InitThreadFuncImpl(size_t thread_idx) override {}
+
+ private:
+  std::vector<std::unique_ptr<CallbackStreamingPingPongReactor>> reactor_;
+};
+
+// TODO(mhaidry) : Implement Streaming from client, server and both ways
+
 std::unique_ptr<Client> CreateCallbackClient(const ClientConfig& config) {
   switch (config.rpc_type()) {
     case UNARY:
       return std::unique_ptr<Client>(new CallbackUnaryClient(config));
     case STREAMING:
+      return std::unique_ptr<Client>(
+          new CallbackStreamingPingPongClientImpl(config));
     case STREAMING_FROM_CLIENT:
     case STREAMING_FROM_SERVER:
     case STREAMING_BOTH_WAYS:
diff --git a/tools/distrib/python/grpcio_tools/grpc_version.py b/tools/distrib/python/grpcio_tools/grpc_version.py
index 29b2127960..e5d9daef38 100644
--- a/tools/distrib/python/grpcio_tools/grpc_version.py
+++ b/tools/distrib/python/grpcio_tools/grpc_version.py
@@ -14,4 +14,4 @@
 
 # AUTO-GENERATED FROM `$REPO_ROOT/templates/tools/distrib/python/grpcio_tools/grpc_version.py.template`!!!
 
-VERSION = '1.18.0.dev0'
+VERSION = '1.19.0.dev0'
diff --git a/tools/dockerfile/interoptest/grpc_interop_ruby/build_interop.sh b/tools/dockerfile/interoptest/grpc_interop_ruby/build_interop.sh
index 67f66090ae..e71ad91499 100755
--- a/tools/dockerfile/interoptest/grpc_interop_ruby/build_interop.sh
+++ b/tools/dockerfile/interoptest/grpc_interop_ruby/build_interop.sh
@@ -30,4 +30,4 @@ cd /var/local/git/grpc
 rvm --default use ruby-2.5
 
 # build Ruby interop client and server
-(cd src/ruby && gem update bundler && bundle && rake compile)
+(cd src/ruby && gem install bundler -v 1.17.3 && bundle && rake compile)
diff --git a/tools/doxygen/Doxyfile.c++ b/tools/doxygen/Doxyfile.c++
index 1ab3a394b9..b0415fd4f6 100644
--- a/tools/doxygen/Doxyfile.c++
+++ b/tools/doxygen/Doxyfile.c++
@@ -40,7 +40,7 @@ PROJECT_NAME           = "GRPC C++"
 # could be handy for archiving the generated documentation or if some version
 # control system is used.
 
-PROJECT_NUMBER         = 1.18.0-dev
+PROJECT_NUMBER         = 1.19.0-dev
 
 # Using the PROJECT_BRIEF tag one can provide an optional one line description
 # for a project that appears at the top of each page and should give viewer a
diff --git a/tools/doxygen/Doxyfile.c++.internal b/tools/doxygen/Doxyfile.c++.internal
index 5f488d5194..6c31a46768 100644
--- a/tools/doxygen/Doxyfile.c++.internal
+++ b/tools/doxygen/Doxyfile.c++.internal
@@ -40,7 +40,7 @@ PROJECT_NAME           = "GRPC C++"
 # could be handy for archiving the generated documentation or if some version
 # control system is used.
 
-PROJECT_NUMBER         = 1.18.0-dev
+PROJECT_NUMBER         = 1.19.0-dev
 
 # Using the PROJECT_BRIEF tag one can provide an optional one line description
 # for a project that appears at the top of each page and should give viewer a