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Provides signal functionality.
template<
typename Executor = executor>
class basic_signal_set
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Name |
Description |
|---|---|
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Rebinds the signal set type to another executor. |
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The type of the executor associated with the object. |
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Name |
Description |
|---|---|
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Add a signal to a signal_set. |
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Start an asynchronous operation to wait for a signal to be delivered. |
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Construct a signal set without adding any signals. |
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Cancel all operations associated with the signal set. |
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Remove all signals from a signal_set. |
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Get the executor associated with the object. |
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Remove a signal from a signal_set. |
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Destroys the signal set. |
The basic_signal_set
class provides the ability to perform an asynchronous wait for one or more
signals to occur.
Distinct objects: Safe.
Shared objects: Unsafe.
Performing an asynchronous wait:
void handler(
const boost::system::error_code& error,
int signal_number)
{
if (!error)
{
// A signal occurred.
}
}
...
// Construct a signal set registered for process termination.
boost::asio::signal_set signals(my_context, SIGINT, SIGTERM);
// Start an asynchronous wait for one of the signals to occur.
signals.async_wait(handler);
If a signal is registered with a signal_set, and the signal occurs when there are no waiting handlers, then the signal notification is queued. The next async_wait operation on that signal_set will dequeue the notification. If multiple notifications are queued, subsequent async_wait operations dequeue them one at a time. Signal notifications are dequeued in order of ascending signal number.
If a signal number is removed from a signal_set (using the remove
or erase member functions) then any queued notifications for
that signal are discarded.
The same signal number may be registered with different signal_set objects. When the signal occurs, one handler is called for each signal_set object.
Note that multiple registration only works for signals that are registered
using Asio. The application must not also register a signal handler using
functions such as signal() or sigaction().
POSIX allows signals to be blocked using functions such as sigprocmask()
and pthread_sigmask(). For signals to be delivered, programs
must ensure that any signals registered using signal_set objects are unblocked
in at least one thread.
Header: boost/asio/basic_signal_set.hpp
Convenience header: boost/asio.hpp