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interceptHandler

virtual void interceptHandler(uintptr_t key, Event*& ev, bool& cancel) override = 0;

This function must be implemented. When a PortModule is installed on the receive side of a port, this function will be called whenever an event is received. It will be called before the event is delivered to a port's handler. The function must do the following depending on what it does with the passed in event.

  • Monitor If the PortModule only monitors the event with no changes, it should set cancel to false.
  • Modify If the PortModule modifies the event, it should set cancel to false.
  • Replace If the PortModule replaces the event with another, it should set cancel to false and must also use copyAllDeliveryInfo to transfer metadata between the original and new events. The function must then delete the original event and set ev to the new event.
  • Delete If the PortModule deletes the event, it should set cancel to true.

The key parameter is inherited from a generic underlying base API that PortModules use and can be ignored in PortModules.

Parameters​

  • key (uintptr_t) A key that identifies the PortModule attach site. This can be ignored and will always be 0 for PortModules.
  • ev (Event*&) A pointer to the event that was received.
  • cancel (bool&) Indicates whether delivery of the event should be cancelled. If set to True, then interceptHandler must also delete the event.
  • returns none

Example​

void DropEvent::interceptHandler(uintptr_t key, Event*& ev, bool& cancel)
{
    uint32_t prob = (rng->getNextUInt32() % 100);
    if (prob <= probability) { // Where 0 <= probability <= 100
        delete ev;
        ev = nullptr;
        cancel = true;
    } else {
        cancel = false;
    }
}
#include <sst/core/portModule.h>