[nanomsg] Re: weird extra byte in header for IPC
- From: Martin Sustrik <sustrik@xxxxxxxxxx>
- To: nanomsg@xxxxxxxxxxxxx
- Date: Tue, 15 Apr 2014 10:31:54 +0200
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Hi Garrett,
> What was the purpose of the extra byte in the IPC header that
> precedes the length (for each message). If not for that one
> difference, the message formats between IPC and TCP/TLS would be
> identical. I’m having a hard time seeing value in that extra
> byte.
>
> (I noticed this tonight when I was trying to use IPC between C and
> my Go version, and I discovered that while I tested TCP, apparently
> I never tested IPC interop… Oops!)
The thing is that with IPC you can actually do zero-copy (store the
data in shared memory, pass the pointer to the other process). Thus,
we need a place to signal that the message is not a standard message
passed via IPC pipe, but rather a descriptor of a block in shared memory.
Martin
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