Boost C++ Libraries of the most highly regarded and expertly designed C++ library projects in the world. Herb Sutter and Andrei Alexandrescu, C++ Coding Standards

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Start an asynchronous operation to wait for a signal to be delivered.

    typename SignalHandler>
void async_wait(
    SignalHandler handler);

This function may be used to initiate an asynchronous wait against the signal set. It always returns immediately.

For each call to async_wait(), the supplied handler will be called exactly once. The handler will be called when:



The handler to be called when the signal occurs. Copies will be made of the handler as required. The function signature of the handler must be:

void handler(
  const boost::system::error_code& error, // Result of operation.
  int signal_number // Indicates which signal occurred.

Regardless of whether the asynchronous operation completes immediately or not, the handler will not be invoked from within this function. Invocation of the handler will be performed in a manner equivalent to using boost::asio::io_service::post().