[lldb] Implement JSON RPC (newline delimited) Transport (llvm#143946)

This PR implements JSON RPC-style (i.e. newline delimited) JSON
transport. I moved the existing transport tests from DAP to Host and
moved the PipeTest base class into TestingSupport so it can be shared by
both.

Author: JDevlieghere

lldb/include/lldb/Host/JSONTransport.h

@@ -51,17 +51,17 @@ class TransportTimeoutError : public llvm::ErrorInfo<TransportTimeoutError> {
   }
 };
 
-class TransportClosedError : public llvm::ErrorInfo<TransportClosedError> {
+class TransportInvalidError : public llvm::ErrorInfo<TransportInvalidError> {
 public:
   static char ID;
 
-  TransportClosedError() = default;
+  TransportInvalidError() = default;
 
   void log(llvm::raw_ostream &OS) const override {
-    OS << "transport is closed";
+    OS << "transport IO object invalid";
   }
   std::error_code convertToErrorCode() const override {
-    return llvm::inconvertibleErrorCode();
+    return std::make_error_code(std::errc::not_connected);
   }
 };
 
@@ -121,6 +121,21 @@ class HTTPDelimitedJSONTransport : public JSONTransport {
   static constexpr llvm::StringLiteral kHeaderSeparator = "\r\n\r\n";
 };
 
+/// A transport class for JSON RPC.
+class JSONRPCTransport : public JSONTransport {
+public:
+  JSONRPCTransport(lldb::IOObjectSP input, lldb::IOObjectSP output)
+      : JSONTransport(input, output) {}
+  virtual ~JSONRPCTransport() = default;
+
+protected:
+  virtual llvm::Error WriteImpl(const std::string &message) override;
+  virtual llvm::Expected<std::string>
+  ReadImpl(const std::chrono::microseconds &timeout) override;
+
+  static constexpr llvm::StringLiteral kMessageSeparator = "\n";
+};
+
 } // namespace lldb_private
 
 #endif

lldb/source/Host/common/JSONTransport.cpp

@@ -31,7 +31,7 @@ static Expected<std::string>
 ReadFull(IOObject &descriptor, size_t length,
          std::optional<std::chrono::microseconds> timeout = std::nullopt) {
   if (!descriptor.IsValid())
-    return llvm::make_error<TransportClosedError>();
+    return llvm::make_error<TransportInvalidError>();
 
   bool timeout_supported = true;
   // FIXME: SelectHelper does not work with NativeFile on Win32.
@@ -92,7 +92,7 @@ void JSONTransport::Log(llvm::StringRef message) {
 Expected<std::string>
 HTTPDelimitedJSONTransport::ReadImpl(const std::chrono::microseconds &timeout) {
   if (!m_input || !m_input->IsValid())
-    return createStringError("transport output is closed");
+    return llvm::make_error<TransportInvalidError>();
 
   IOObject *input = m_input.get();
   Expected<std::string> message_header =
@@ -131,7 +131,7 @@ HTTPDelimitedJSONTransport::ReadImpl(const std::chrono::microseconds &timeout) {
 
 Error HTTPDelimitedJSONTransport::WriteImpl(const std::string &message) {
   if (!m_output || !m_output->IsValid())
-    return llvm::make_error<TransportClosedError>();
+    return llvm::make_error<TransportInvalidError>();
 
   Log(llvm::formatv("<-- {0}", message).str());
 
@@ -142,6 +142,35 @@ Error HTTPDelimitedJSONTransport::WriteImpl(const std::string &message) {
   return m_output->Write(Output.data(), num_bytes).takeError();
 }
 
+Expected<std::string>
+JSONRPCTransport::ReadImpl(const std::chrono::microseconds &timeout) {
+  if (!m_input || !m_input->IsValid())
+    return make_error<TransportInvalidError>();
+
+  IOObject *input = m_input.get();
+  Expected<std::string> raw_json =
+      ReadUntil(*input, kMessageSeparator, timeout);
+  if (!raw_json)
+    return raw_json.takeError();
+
+  Log(llvm::formatv("--> {0}", *raw_json).str());
+
+  return *raw_json;
+}
+
+Error JSONRPCTransport::WriteImpl(const std::string &message) {
+  if (!m_output || !m_output->IsValid())
+    return llvm::make_error<TransportInvalidError>();
+
+  Log(llvm::formatv("<-- {0}", message).str());
+
+  std::string Output;
+  llvm::raw_string_ostream OS(Output);
+  OS << message << kMessageSeparator;
+  size_t num_bytes = Output.size();
+  return m_output->Write(Output.data(), num_bytes).takeError();
+}
+
 char TransportEOFError::ID;
 char TransportTimeoutError::ID;
-char TransportClosedError::ID;
+char TransportInvalidError::ID;

lldb/unittests/DAP/CMakeLists.txt

@@ -7,7 +7,6 @@ add_lldb_unittest(DAPTests
   LLDBUtilsTest.cpp
   ProtocolTypesTest.cpp
   TestBase.cpp
-  TransportTest.cpp
   VariablesTest.cpp
 
   LINK_COMPONENTS

lldb/unittests/DAP/TestBase.cpp

@@ -28,13 +28,8 @@ using lldb_private::File;
 using lldb_private::NativeFile;
 using lldb_private::Pipe;
 
-void PipeBase::SetUp() {
-  ASSERT_THAT_ERROR(input.CreateNew(false).ToError(), Succeeded());
-  ASSERT_THAT_ERROR(output.CreateNew(false).ToError(), Succeeded());
-}
-
 void TransportBase::SetUp() {
-  PipeBase::SetUp();
+  PipeTest::SetUp();
   to_dap = std::make_unique<Transport>(
       "to_dap", nullptr,
       std::make_shared<NativeFile>(input.GetReadFileDescriptor(),

lldb/unittests/DAP/TestBase.h

@@ -8,26 +8,17 @@
 
 #include "DAP.h"
 #include "Protocol/ProtocolBase.h"
+#include "TestingSupport/Host/PipeTestUtilities.h"
 #include "Transport.h"
-#include "lldb/Host/Pipe.h"
 #include "llvm/ADT/StringRef.h"
 #include "gmock/gmock.h"
 #include "gtest/gtest.h"
 
 namespace lldb_dap_tests {
 
-/// A base class for tests that need a pair of pipes for communication.
-class PipeBase : public testing::Test {
-protected:
-  lldb_private::Pipe input;
-  lldb_private::Pipe output;
-
-  void SetUp() override;
-};
-
 /// A base class for tests that need transport configured for communicating DAP
 /// messages.
-class TransportBase : public PipeBase {
+class TransportBase : public PipeTest {
 protected:
   std::unique_ptr<lldb_dap::Transport> to_dap;
   std::unique_ptr<lldb_dap::Transport> from_dap;

lldb/unittests/DAP/TransportTest.cpp

@@ -6,6 +6,7 @@ set (FILES
   HostInfoTest.cpp
   HostTest.cpp
   MainLoopTest.cpp
+  JSONTransportTest.cpp
   NativeProcessProtocolTest.cpp
   PipeTest.cpp
   ProcessLaunchInfoTest.cpp