Function qpid_proton_sys::pn_link_credit

pub unsafe extern "C" fn pn_link_credit(link: *mut pn_link_t) -> i64

Get the credit balance for a link. Links use a credit based flow control scheme. Every receiver maintains a credit balance that corresponds to the number of deliveries that the receiver can accept at any given moment. As more capacity becomes available at the receiver (see pn_link_flow), it adds credit to this balance and communicates the new balance to the sender. Whenever a delivery is sent/received, the credit balance maintained by the link is decremented by one. Once the credit balance at the sender reaches zero, the sender must pause sending until more credit is obtained from the receiver. Note that a sending link may still be used to send deliveries even if pn_link_credit reaches zero, however those deliveries will end up being buffered by the link until enough credit is obtained from the receiver to send them over the wire. In this case the balance reported by pn_link_credit will go negative.