Weave port [5/n]: Introduce weave message write request

PiperOrigin-RevId: 530915704

internal/weave/message_write_request.h

@@ -0,0 +1,77 @@
+// Copyright 2023 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef THIRD_PARTY_NEARBY_INTERNAL_WEAVE_MESSAGE_WRITE_REQUEST_H_
+#define THIRD_PARTY_NEARBY_INTERNAL_WEAVE_MESSAGE_WRITE_REQUEST_H_
+
+#include <string>
+
+#include "internal/platform/future.h"
+#include "internal/weave/packet.h"
+
+namespace nearby {
+namespace weave {
+
+// Implementation of WriteRequest interface that exists to serialize messages
+// into Weave packets and track the sending progress.
+//
+// This class is not thread-safe, calls to this class will be serialized at the
+// socket level.
+class MessageWriteRequest {
+ public:
+  explicit MessageWriteRequest(absl::string_view message);
+  MessageWriteRequest(MessageWriteRequest&& other) = default;
+  MessageWriteRequest& operator=(MessageWriteRequest&& other) = default;
+
+  bool IsStarted() const;
+  bool IsFinished() const;
+
+  absl::StatusOr<Packet> NextPacket(int max_packet_size);
+
+  // Gets the future result, the socket will set this result in the future.
+  // The socket only sets the result once the request has been completed.
+  nearby::Future<absl::Status> GetWriteStatusFuture() {
+    return write_request_status_;
+  }
+
+  // This function sets the nearby::Future instance from GetResultFuture() and
+  // is called when the caller manages to successfully write the packets in
+  // this WriteRequest (as indicated by IsFinished()), or when the caller learns
+  // that a packet could not be sent across the wire due to an error or
+  // disconnection.
+  void SetWriteStatus(absl::Status status) {
+    write_request_status_.Set(status);
+  }
+
+  // Two message write requests are the same if they have the same message,
+  // even if they have different progress members due to referencing and
+  // other quirks.
+  bool operator==(const MessageWriteRequest& other) const {
+    return message_ == other.message_;
+  }
+
+  bool operator!=(const MessageWriteRequest& other) const {
+    return !(*this == other);
+  }
+
+ private:
+  std::string message_;
+  int position_;
+  nearby::Future<absl::Status> write_request_status_;
+};
+
+}  // namespace weave
+}  // namespace nearby
+
+#endif  // THIRD_PARTY_NEARBY_INTERNAL_WEAVE_MESSAGE_WRITE_REQUEST_H_