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Provides signal functionality.
template< typename SignalSetService = signal_set_service> class basic_signal_set : public basic_io_object< SignalSetService >
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Description |
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The type of the executor associated with the object. |
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The underlying implementation type of I/O object. |
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The type of the service that will be used to provide I/O operations. |
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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. Construct a signal set and add one signal. Construct a signal set and add two signals. Construct a signal set and add three 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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(Deprecated: Use get_executor().) Get the io_service associated with the object. |
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Remove a signal from a signal_set. |
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Get the underlying implementation of the I/O object. |
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Get the service associated with the I/O object. |
The basic_signal_set
class template provides the ability to perform an asynchronous wait for one
or more signals to occur.
Most applications will use the signal_set typedef.
Distinct objects: Safe.
Shared objects: Unsafe.
Performing an asynchronous wait:
void handler( const asio::error_code& error, int signal_number) { if (!error) { // A signal occurred. } } ... // Construct a signal set registered for process termination. asio::signal_set signals(io_service, 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: asio/basic_signal_set.hpp
Convenience header: asio.hpp