At that point I'd probably use "repeated bytes", then. It'll cost you an
extra byte on v4 addresses, but it is simple.
On Wed, 18 Jul 2018, 09:36 sanjana gupta, <sanjana.gupta...@gmail.com>
wrote:
> Thanks Marc for your reply! By mistake I wrote 8-bytes for ipv4. I have
> corrected it as 4-bytes in my question. Thanks for that :)
>
> One thing I want to ask you is that can I use "oneof" if my field
> "localEndpoint" is repeated?
> I mean to say that my one "profile" message can have any among :
> -> 2 ipv4 addresses
> -> OR 2 ipv6 addresses
> -> OR 1 ipv4 + 1 ipv6 addresses
> in the field "localEndpoint".
>
> So in that case, is "oneof" usage correct? I think that a "oneof" cannot
> be repeated. Please correct me if I am wrong.
>
> On Wednesday, July 18, 2018 at 12:54:39 PM UTC+5:30, Marc Gravell wrote:
>>
>> You should be able to encode ipv4 in 4 bytes, making fixed32 ideal, since
>> you can avoid the length prefix. For ipv6, you're going to need 16 bytes,
>> so "bytes" is probably your best bet, since it will only require a single
>> header. You can then create a union of those:
>>
>> oneof ip_addr {
>> fixed32 v4 = 1;
>> bytes v6 = 2;
>> }
>>
>> That seems pretty optimal to me.
>>
>> Marc
>>
>> On Wed, 18 Jul 2018, 08:16 sanjana gupta, <sanjana....@gmail.com> wrote:
>>
>>> I read that protobuf has a type called "*bytes*" which can store
>>> arbitrary number of bytes and is the equivalent of "C++ string".
>>>
>>> The reason why I don't prefer to use "bytes" is that it expects input as
>>> a C++ string i.e., boost IP will need to be converted to a string.
>>>
>>>
>>> Now my concern lies here : I want to perform serialize and send the
>>> encoded protobuf message over TCP socket. I want to ensure that the *encoded
>>> message size is as small as possible*.
>>>
>>>
>>> Currently, I am using the below .proto file :
>>>
>>> syntax = "proto2";
>>>
>>> message profile
>>>
>>> {
>>>
>>> repeated *uint32* localEndpoint = 1;
>>>
>>> repeated *uint32* remoteEndpoint = 2;
>>>
>>> }
>>>
>>>
>>> In order to save boost IP in the protobuf message, I am first converting
>>> boost IP into byte-format array by using
>>> "boost::asio::ip::address_v4::to_bytes()". So for a v4 IP, resultant array
>>> size is 8. Then I am converting 1st 4 bytes from the resultant byte-array
>>> into one uint32_t number and then storing in "localEndpoint" field of the
>>> protobuf message. Likewise, I repeat for the next 4 bytes. I am taking 4
>>> bytes at a time so as to utilize full 32 bits of the uint32.
>>>
>>>
>>> Hence for a v4 address, 2 occurrence of "localEndpoint" field is used.
>>> Similarly, for a v6 address, 4 occurrence of "localEndpoint" field is used.
>>>
>>>
>>> Please allow me to highlight that if I had used "bytes" here, my input
>>> string itself would have been of size 15 bytes for a v4 ip like
>>> 111.111.111.111
>>>
>>>
>>> Using uint32 instead of "bytes" does save me some encoded-data-size but
>>> I am looking for a more efficient protobuf type requiring lesser number of
>>> bytes.
>>>
>>>
>>> Sorry for a long description but I wanted to explain my query in
>>> details. Please help me.. Thanks a lot in advance :)
>>>
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