Add documentation for signal_set.
diff --git a/asio/include/asio/basic_signal_set.hpp b/asio/include/asio/basic_signal_set.hpp index 2d66907..9282766 100644 --- a/asio/include/asio/basic_signal_set.hpp +++ b/asio/include/asio/basic_signal_set.hpp
@@ -28,18 +28,97 @@ namespace asio { /// Provides signal functionality. +/** + * 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 asio::signal_set typedef. + * + * @par Thread Safety + * @e Distinct @e objects: Safe.@n + * @e Shared @e objects: Unsafe. + * + * @par Example + * Performing an asynchronous wait: + * @code + * 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); + * @endcode + * + * @par Queueing of signal notifications + * + * 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 @c remove or @c + * erase member functions) then any queued notifications for that signal are + * discarded. + * + * @par Multiple registration of signals + * + * 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 @c signal() or @c sigaction(). + * + * @par Signal masking on POSIX platforms + * + * POSIX allows signals to be blocked using functions such as @c sigprocmask() + * and @c 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. + */ template <typename SignalSetService = signal_set_service> class basic_signal_set : public basic_io_object<SignalSetService> { public: /// Construct a signal set without adding any signals. + /** + * This constructor creates a signal set without registering for any signals. + * + * @param io_service The io_service object that the signal set will use to + * dispatch handlers for any asynchronous operations performed on the set. + */ explicit basic_signal_set(asio::io_service& io_service) : basic_io_object<SignalSetService>(io_service) { } /// Construct a signal set and add one signal. + /** + * This constructor creates a signal set and registers for one signal. + * + * @param io_service The io_service object that the signal set will use to + * dispatch handlers for any asynchronous operations performed on the set. + * + * @param signal_number_1 The signal number to be added. + * + * @note This constructor is equivalent to performing: + * @code asio::signal_set signals(io_service); + * signals.add(signal_number_1); @endcode + */ basic_signal_set(asio::io_service& io_service, int signal_number_1) : basic_io_object<SignalSetService>(io_service) { @@ -49,6 +128,21 @@ } /// Construct a signal set and add two signals. + /** + * This constructor creates a signal set and registers for two signals. + * + * @param io_service The io_service object that the signal set will use to + * dispatch handlers for any asynchronous operations performed on the set. + * + * @param signal_number_1 The first signal number to be added. + * + * @param signal_number_2 The second signal number to be added. + * + * @note This constructor is equivalent to performing: + * @code asio::signal_set signals(io_service); + * signals.add(signal_number_1); + * signals.add(signal_number_2); @endcode + */ basic_signal_set(asio::io_service& io_service, int signal_number_1, int signal_number_2) : basic_io_object<SignalSetService>(io_service) @@ -61,6 +155,24 @@ } /// Construct a signal set and add three signals. + /** + * This constructor creates a signal set and registers for three signals. + * + * @param io_service The io_service object that the signal set will use to + * dispatch handlers for any asynchronous operations performed on the set. + * + * @param signal_number_1 The first signal number to be added. + * + * @param signal_number_2 The second signal number to be added. + * + * @param signal_number_3 The third signal number to be added. + * + * @note This constructor is equivalent to performing: + * @code asio::signal_set signals(io_service); + * signals.add(signal_number_1); + * signals.add(signal_number_2); + * signals.add(signal_number_3); @endcode + */ basic_signal_set(asio::io_service& io_service, int signal_number_1, int signal_number_2, int signal_number_3) : basic_io_object<SignalSetService>(io_service) @@ -75,6 +187,14 @@ } /// Add a signal to a signal_set. + /** + * This function adds the specified signal to the set. It has no effect if the + * signal is already in the set. + * + * @param signal_number The signal to be added to the set. + * + * @throws asio::system_error Thrown on failure. + */ void add(int signal_number) { asio::error_code ec; @@ -83,13 +203,32 @@ } /// Add a signal to a signal_set. + /** + * This function adds the specified signal to the set. It has no effect if the + * signal is already in the set. + * + * @param signal_number The signal to be added to the set. + * + * @param ec Set to indicate what error occurred, if any. + */ asio::error_code add(int signal_number, asio::error_code& ec) { return this->service.add(this->implementation, signal_number, ec); } - /// Remove a signal to a signal_set. + /// Remove a signal from a signal_set. + /** + * This function removes the specified signal from the set. It has no effect + * if the signal is not in the set. + * + * @param signal_number The signal to be removed from the set. + * + * @throws asio::system_error Thrown on failure. + * + * @note Removes any notifications that have been queued for the specified + * signal number. + */ void remove(int signal_number) { asio::error_code ec; @@ -97,7 +236,18 @@ asio::detail::throw_error(ec); } - /// Remove a signal to a signal_set. + /// Remove a signal from a signal_set. + /** + * This function removes the specified signal from the set. It has no effect + * if the signal is not in the set. + * + * @param signal_number The signal to be removed from the set. + * + * @param ec Set to indicate what error occurred, if any. + * + * @note Removes any notifications that have been queued for the specified + * signal number. + */ asio::error_code remove(int signal_number, asio::error_code& ec) { @@ -105,6 +255,14 @@ } /// Remove all signals from a signal_set. + /** + * This function removes all signals from the set. It has no effect if the set + * is already empty. + * + * @throws asio::system_error Thrown on failure. + * + * @note Removes all queued notifications. + */ void clear() { asio::error_code ec; @@ -113,12 +271,40 @@ } /// Remove all signals from a signal_set. + /** + * This function removes all signals from the set. It has no effect if the set + * is already empty. + * + * @param ec Set to indicate what error occurred, if any. + * + * @note Removes all queued notifications. + */ asio::error_code clear(asio::error_code& ec) { return this->service.clear(this->implementation, ec); } /// Cancel all operations associated with the signal set. + /** + * This function forces the completion of any pending asynchronous wait + * operations against the signal set. The handler for each cancelled + * operation will be invoked with the asio::error::operation_aborted + * error code. + * + * Cancellation does not alter the set of registered signals. + * + * @throws asio::system_error Thrown on failure. + * + * @note If a registered signal occurred before cancel() is called, then the + * handlers for asynchronous wait operations will: + * + * @li have already been invoked; or + * + * @li have been queued for invocation in the near future. + * + * These handlers can no longer be cancelled, and therefore are passed an + * error code that indicates the successful completion of the wait operation. + */ void cancel() { asio::error_code ec; @@ -127,12 +313,56 @@ } /// Cancel all operations associated with the signal set. + /** + * This function forces the completion of any pending asynchronous wait + * operations against the signal set. The handler for each cancelled + * operation will be invoked with the asio::error::operation_aborted + * error code. + * + * Cancellation does not alter the set of registered signals. + * + * @param ec Set to indicate what error occurred, if any. + * + * @note If a registered signal occurred before cancel() is called, then the + * handlers for asynchronous wait operations will: + * + * @li have already been invoked; or + * + * @li have been queued for invocation in the near future. + * + * These handlers can no longer be cancelled, and therefore are passed an + * error code that indicates the successful completion of the wait operation. + */ asio::error_code cancel(asio::error_code& ec) { return this->service.cancel(this->implementation, ec); } // Start an asynchronous operation to wait for a signal to be delivered. + /** + * 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: + * + * @li One of the registered signals in the signal set occurs; or + * + * @li The signal set was cancelled, in which case the handler is passed the + * error code asio::error::operation_aborted. + * + * @param handler 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: + * @code void handler( + * const asio::error_code& error, // Result of operation. + * int signal_number // Indicates which signal occurred. + * ); @endcode + * 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 + * asio::io_service::post(). + */ template <typename SignalHandler> void async_wait(SignalHandler handler) {