...one of the most highly
regarded and expertly designed C++ library projects in the
world.
— Herb Sutter and Andrei
Alexandrescu, C++
Coding Standards
Typedef for the typical usage of timer.
typedef basic_deadline_timer< boost::posix_time::ptime > deadline_timer;
Name |
Description |
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The duration type. |
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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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The time type. |
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The time traits type. |
Name |
Description |
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Start an asynchronous wait on the timer. |
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Constructor. Constructor to set a particular expiry time as an absolute time. Constructor to set a particular expiry time relative to now. |
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Cancel any asynchronous operations that are waiting on the timer. |
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Get the timer's expiry time as an absolute time. Set the timer's expiry time as an absolute time. |
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Get the timer's expiry time relative to now. Set the timer's expiry time relative to now. |
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Get the io_service associated with the object. |
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(Deprecated: use get_io_service().) Get the io_service associated with the object. |
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Perform a blocking wait on the timer. |
Name |
Description |
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The underlying implementation of the I/O object. |
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The service associated with the I/O object. |
The basic_deadline_timer class template provides the ability to perform a blocking or asynchronous wait for a timer to expire.
Most applications will use the boost::asio::deadline_timer typedef.
Distinct objects: Safe.
Shared objects: Unsafe.
Performing a blocking wait:
// Construct a timer without setting an expiry time. boost::asio::deadline_timer timer(io_service); // Set an expiry time relative to now. timer.expires_from_now(boost::posix_time::seconds(5)); // Wait for the timer to expire. timer.wait();
Performing an asynchronous wait:
void handler(const boost::system::error_code& error) { if (!error) { // Timer expired. } } ... // Construct a timer with an absolute expiry time. boost::asio::deadline_timer timer(io_service, boost::posix_time::time_from_string("2005-12-07 23:59:59.000")); // Start an asynchronous wait. timer.async_wait(handler);
Changing the expiry time of a timer while there are pending asynchronous waits causes those wait operations to be cancelled. To ensure that the action associated with the timer is performed only once, use something like this: used:
void on_some_event() { if (my_timer.expires_from_now(seconds(5)) > 0) { // We managed to cancel the timer. Start new asynchronous wait. my_timer.async_wait(on_timeout); } else { // Too late, timer has already expired! } } void on_timeout(const boost::system::error_code& e) { if (e != boost::asio::error::operation_aborted) { // Timer was not cancelled, take necessary action. } }