> I can store it in my key-value store as a string too
It is hard to tell as we know nothing about your store.
A char pointer is just an address into your memory. It has no information
about the size of the block.
If you interpret this pointer as a character string, the convention is that
this string ends with the very first nul byte.
If it is the address a blob, no one can tell how long it is.
But this actually has nothing to do the with GRPC - this is very basic
string/memory handling of C++
On Thursday, December 3, 2020 at 5:10:49 PM UTC+1 Joseph Liu wrote:
> So basically, send val as a string, and even when we receive it on the
> server side, I can store it in my key-value store as a string too? (Right
> now I'm storing it as a char*)
>
> On Thursday, December 3, 2020 at 4:04:02 PM UTC tobias.krueger wrote:
>
>> The std::string, which is used as the container for the grpc datatype
>> "bytes", can handle embedded nul bytes.
>> But In your "Put" method you pass the parameter "val" as char * pointer.
>> This char * pointer will be converted to a std::string terminating with
>> the first occurrence of the nul byte.
>>
>> So must either past the value "val" as std::string or std::vector<char>
>>
>> HTH
>> Tobias
>>
>> On Thursday, December 3, 2020 at 4:59:05 PM UTC+1 Joseph Liu wrote:
>>
>>> So I'm using gRPC to store data in a key-value store.
>>>
>>> The protos look like this:
>>>
>>> syntax = "proto3";
>>>
>>> package keyvaluestore;
>>>
>>> service KeyValueStore {
>>> rpc AddUser(Credentials) returns (Response) {}
>>> rpc Get(Request) returns (Response) {}
>>> rpc Put(Request) returns (Response) {}
>>> rpc Cput(Request) returns (Response) {}
>>> rpc Delete(Request) returns (Response) {}
>>> }
>>>
>>> message Credentials {
>>> string user = 1;
>>> string passwd = 2;
>>> }
>>>
>>> message Request {
>>> string user = 1;
>>> string key = 2;
>>> bytes val = 3;
>>> bytes val2 = 4;
>>> string addr = 5;
>>> }
>>>
>>> message Response {
>>> bytes val = 1;
>>> uint32 nbytes = 2;
>>> string message = 3;
>>> }
>>>
>>> Right now, the issue is that if we send over say, an image as byte data
>>> which can include the null byte, then when the server receives it in the
>>> `Request` object, it treats it as a string; when it does this it only reads
>>> it up the the first null byte.
>>>
>>> How we pack the `Request` object on the client side:
>>>
>>> bool KeyValueStoreClient::Put(const string& user, const string& key,
>>> const char* val) {
>>> Request req;
>>> req.set_user(user);
>>> req.set_key(key);
>>> req.set_val(val);
>>>
>>> ClientContext ctx;
>>> Response res;
>>> Status status = stub_->Put(&ctx, req, &res);
>>> }
>>>
>>> Server receives `req->val()` as a string instead of `char*`:
>>>
>>> Status KeyValueStoreServiceImpl::Put(ServerContext* ctx, const
>>> Request* req, Response* res) {
>>> // req->val() is a string
>>>
>>> }
>>>
>>>
>>>
>>>
>>>
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