How to know if std::cin is blocking a thread?

[highronn]

Hello,
I want to synchronize 2 differents processes by using cin has a synchroniser.
one proccess is a consumer the other one is a producer. But I want to produce (put values in cin buffer) from the producer process only when the consumer process is blocked by calling "cin >> some_var".
Is there any way to achieve this?

[Aceix]

there should be a way which should involve multi-threading.

Aceix.