Protobuf and Non-blocking message send/recv

Question

I am developing my message passing interface using protobuf and non-blocking libevent socket libraries. Because of the non-blocking properties, the read callback by libevent might be invoked at some points where the messages are not complete (eg, every 4096 bytes received). This means I have to write another wrapper/header indicating the size of each message so I can parse the message back to the protobuf object correctly. Are there better solutions for this? Or does protobuf provide an API to handle this situation?

Answer 1

No, there is no better solution. In fact, even when using blocking I/O, you need to write a header indicating the size, because Protobufs are not self-delimiting (by default the protobuf parser will always read until EOF!).