[Lldb-commits] [lldb] [lldb] Update JSONTransport to use MainLoop for reading. (PR #152367)

[John Harrison via lldb-commits]

================
@@ -83,24 +86,68 @@ class JSONTransport {
     return WriteImpl(message);
   }
 
-  /// Reads the next message from the input stream.
+  /// Registers the transport with the MainLoop.
   template <typename T>
-  llvm::Expected<T> Read(const std::chrono::microseconds &timeout) {
-    llvm::Expected<std::string> message = ReadImpl(timeout);
-    if (!message)
-      return message.takeError();
-    return llvm::json::parse<T>(/*JSON=*/*message);
+  llvm::Expected<ReadHandleUP> RegisterReadObject(MainLoopBase &loop,
+                                                  Callback<T> read_cb) {
+    Status error;
+    ReadHandleUP handle = loop.RegisterReadObject(
+        m_input,
+        [read_cb, this](MainLoopBase &loop) {
+          char buf[kReadBufferSize];
+          size_t num_bytes = sizeof(buf);
+          if (llvm::Error error = m_input->Read(buf, num_bytes).takeError()) {
+            read_cb(loop, std::move(error));
+            return;
+          }
+          if (num_bytes)
+            m_buffer.append(std::string(buf, num_bytes));
+
+          // If the buffer has contents, try parsing any pending messages.
+          if (!m_buffer.empty()) {
+            llvm::Expected<std::vector<std::string>> messages = Parse();
+            if (llvm::Error error = messages.takeError()) {
+              read_cb(loop, std::move(error));
+              return;
+            }
+
+            for (const auto &message : *messages)
+              if constexpr (std::is_same<T, std::string>::value)
+                read_cb(loop, message);
+              else
+                read_cb(loop, llvm::json::parse<T>(message));
+          }
+
+          // On EOF, notify the callback after the remaining messages were
+          // handled.
+          if (num_bytes == 0) {
+            if (m_buffer.empty())
+              read_cb(loop, llvm::make_error<TransportEOFError>());
+            else
+              read_cb(loop, llvm::make_error<TransportUnhandledContentsError>(
+                                std::string(m_buffer)));
+          }
+        },
+        error);
+    if (error.Fail())
+      return error.takeError();
+    return handle;
   }
 
 protected:
+  template <typename... Ts> inline auto Logv(const char *Fmt, Ts &&...Vals) {
+    Log(llvm::formatv(Fmt, std::forward<Ts>(Vals)...).str());
+  }
   virtual void Log(llvm::StringRef message);
 
   virtual llvm::Error WriteImpl(const std::string &message) = 0;
-  virtual llvm::Expected<std::string>
-  ReadImpl(const std::chrono::microseconds &timeout) = 0;
+  virtual llvm::Expected<std::vector<std::string>> Parse() = 0;
 
   lldb::IOObjectSP m_input;
   lldb::IOObjectSP m_output;
+  llvm::SmallString<128> m_buffer;
----------------
ashgti wrote:

Done.

https://github.com/llvm/llvm-project/pull/152367