boost::deadline_timer
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boost::deadline_timer
定义
typedef basic_deadline_timer<boost::posix_time::ptime> deadline_timer;
basic_deadline_timer是个模板类。
构造函数
deadline_timer有三个构造函数:
1 explicit basic_deadline_timer(boost::asio::io_service& io_service)
: basic_io_object<TimerService>(io_service)
{
}
构造函数有一个参数io_service,几乎所有asio的程序都用到io_service(这个类以后再学习)。这个
构造函数创建了一个没有结束时间的定时器。在使用这个定时器之前,我们必须条用其成员函数expires_at或
expires_from_now来设置结束时间。
例子:
boost::asio::deadline_timer t1(io);t1.expires_from_now(boost::posix_time::seconds(1));//从现在开始1秒后结束
2 basic_deadline_timer(boost::asio::io_service& io_service, const time_type& expiry_time)
: basic_io_object<TimerService>(io_service)
{
}
此构造函数有两个参数,第二个函数类型time_type对deadlien_timer来说是ptime类型,这个构造函数创建了一个绝对时间的定时器。定时器在时间为expiry_time时结束。
例子:
std::string abstime = "2015-01-22 13:10:23"boost::asio::deadline_timer t2(io, boost::posix_time::time_from_string(abstime));//构造一个绝对定失效的定时器这里time_from_string()函数会把abstime转换成ptime类型的时间
3 basic_deadline_timer(boost::asio::io_service& io_service, const duration_type& expiry_time)
: basic_io_object<TimerService>(io_service)
{
}
此构造函数也有两个参数,第二个参数类型duration_type是个相对时间,相对当前时间可以秒、分、时等等。
例子:
boost::asio::deadline_timer t(io, boost::posix_time::seconds(2));//从当前时间开始2s以后结束
成员函数
1 std::size_t cancel()
此函数将取消定时器;同时任何在等待此定时器的异步操作都被取消,所有被取消异步操作的handler都会被调用,参数error_code被设置为boost::asio::error::operation_aborted。
返回被取消异步操作的个数,同时抛出boost::system::system_error Thrown on failure。 注意当在调用cancel这个函数时,定时器刚好结束,任何在等待被调用队列的异步操作将不会被取消,任何正在被调用的异步操作将不会被取消。
2 std::size_t cancel(boost::system::error_code& ec)
这个函数的作用和无参数的cancel()函数作用相同。在调用此函数时如果出现错误,参数ec指出出现什么错误。
3 std::size_t cancel_one()
此函数将取消定时器,并且强制一个在等待此定时器的异步操作被被取消,这个被取消异步操作的handler被调用,调用顺FIFO,参数error_code被设置为boost::asio::error::operation_aborted。
返回值为0或1。
注意其他在等待的异步操作在定时器结束时,还会被调用,看例子:
void handle_expriesfn(const boost::system::error_code& error, int flag){if (error != boost::asio::error::operation_aborted){flag ? (std::cout << "I have something to do..." << std::endl) : (std::cout << "I have nothing to do....." << std::endl);}else{std::cout << __FUNCTION__ << " handler is invalid" << std::endl;}}void test_cancel(){boost::asio::io_service io;boost::asio::deadline_timer t(io, boost::posix_time::seconds(2));t.async_wait(boost::bind(handle_expriesfn, boost::asio::placeholders::error, 0));t.async_wait(boost::bind(handle_expriesfn, boost::asio::placeholders::error, 1));boost::system::error_code err;t.cancel_one(err);//第一个handler会立即被调用error_code被置为boost::asio::error::operation_aborted,第二个handler在定时器结束时才被调用io.run();}
4 time_type expires_at() const
返回定时器当前的结束时间(定时器结束时间可以被重置)。
5 std::size_t expires_at(const time_type& expiry_time)
重新设置定时器的结束时间。参数expiry_time是绝对时间。
注意任何在等待此定时器的异步操作都被取消,所有被取消异步操作的handler都会被调用,参数error_code被设置为boost::asio::error::operation_aborted。
返回被取消异步操作的个数,同时抛出boost::system::system_error Thrown on failure。
当在调用expires_at这个函数时,定时器刚好结束,任何在等待被调用队列的异步操作将不会被取消,任何正在被调用的异步操作将不会被取消。
列子:
void on_any_event(boost::asio::deadline_timer& timer, int flag){//expires_at(abstime)函数重新设置定时器时间,以前正在等待此定时器的handler都会被取消//返回被取消的handler个数(return The number of asynchronous operations that were canceled)size_t cancelednum = timer.expires_at(timer.expires_at() + boost::posix_time::seconds(2));if (cancelednum > 0){std::cout << "the canceled handler is " << cancelednum << std::endl;timer.async_wait(boost::bind(handle_expriesfn, boost::asio::placeholders::error, flag));timer.async_wait(boost::bind(handle_expriesfn, boost::asio::placeholders::error, !flag));}else{std::cout << "too late, timer has expried" <<std::endl;}}void test_expires_at(){boost::asio::io_service io;boost::asio::deadline_timer t(io, boost::posix_time::seconds(2));t.async_wait(boost::bind(handle_expriesfn, boost::asio::placeholders::error, 0));t.async_wait(boost::bind(handle_expriesfn, boost::asio::placeholders::error, 1));on_any_event(t, 0);//取消定时器io.run();}
6 std::size_t expires_at(const time_type& expiry_time, boost::system::error_code& ec)
这个函数作用同第5个函数。在调用此函数时如果出现错误,参数ec指出出现什么错误。
7 duration_type expires_from_now() const
返回定时器从现在开始到结束时的时间。
8 std::size_t expires_from_now(const duration_type& expiry_time)
重新设置定时器的结束时间,这个时间相对当前时间的。
注意任何在等待此定时器的异步操作都被取消,所有被取消异步操作的handler都会被调用,参数error_code被设置为boost::asio::error::operation_aborted。
返回被取消异步操作的个数,同时抛出boost::system::system_error Thrown on failure。
当在调用expires_at这个函数时,定时器刚好结束,任何在等待被调用队列的异步操作将不会被取消,任何正在被调用的异步操作将不会被取消。
例子:
void on_some_event(boost::asio::deadline_timer& timer, int flag){//expires_from_now(relativetime)函数重新设置定时器时间,以前正在等待此定时器的handler都会被取消//返回被取消的handler个数(return The number of asynchronous operations that were cancelled)size_t cancelednum = timer.expires_from_now(boost::posix_time::seconds(2));if (cancelednum > 0){std::cout << "the cancelled handler is " << cancelednum << std::endl;timer.async_wait(boost::bind(handle_expriesfn, boost::asio::placeholders::error, flag));}else{std::cout << "too late, timer has expried" <<std::endl;}}void test_expries_from_now(){boost::asio::io_service io;boost::asio::deadline_timer t(io, boost::posix_time::seconds(2));t.async_wait(boost::bind(handle_expriesfn, boost::asio::placeholders::error, 0));t.async_wait(boost::bind(handle_expriesfn, boost::asio::placeholders::error, 1));on_some_event(t, 0);//取消定时器io.run();}
9 std::size_t expires_from_now(const duration_type& expiry_time, boost::system::error_code& ec)
这个函数作用同第8个函数。在调用此函数时如果出现错误,参数ec指出出现什么错误。
10 void wait() or wait(boost::system::error_code& ec)
等待定时器结束。如果定时器不结束,此函数不返回。
11 async_wait(handler())
a 会立即返回,handler函数不会在这个函数这里调用,
b handler会在定时器结束
c 或定时器被取消是调用,这时error_code值为boost::asio::error::operation_aborted
下面是测试的列子:
deadtimer.h
void testSyncDT(){std::cout << "After 2s will output: ";boost::asio::io_service io;boost::asio::deadline_timer t(io, boost::posix_time::seconds(2));t.wait();//wait()会阻塞直到定时器结束才返回//下面的代码不会执行直到wait函数返回std::cout << "hello world" << std::endl;std::cout << "After 1s will output: ";boost::asio::deadline_timer t1(io);t1.expires_from_now(boost::posix_time::seconds(1));//从现在开始1秒后结束t1.wait();std::cout << "hello world again" << std::endl;}void handler(const boost::system::error_code& error){if (!error){//do something...std::cout << "handler is called" << std::endl;}else {std::cout << "handler is invalid" << std::endl;}}void print_posix_time_to_string(const boost::system::error_code& error, const boost::posix_time::ptime& pt){if (error != boost::asio::error::operation_aborted){std::cout << "to_iso_string: " << boost::posix_time::to_iso_string(pt) << std::endl;std::cout << "to_iso_extended_string: " << boost::posix_time::to_iso_extended_string(pt) << std::endl;std::cout << "to_sample_string: " << boost::posix_time::to_simple_string(pt) << std::endl;}else{std::cout << __FUNCTION__ << " handler is invalid" << std::endl;}}void testAsyncDT(){boost::posix_time::ptime postime = boost::posix_time::second_clock::local_time();std::string strt = boost::posix_time::to_iso_extended_string(postime);std::cout << strt << std::endl;boost::posix_time::ptime pst = boost::posix_time::time_from_string("2015-01-22 15:38:00");std::cout << pst << std::endl;boost::asio::io_service io;//构造一个相对的定时器boost::asio::deadline_timer t(io, boost::posix_time::seconds(2));t.async_wait(&handler);//async_wait()会立即返回,handler函数不会在这里调用,//handler会在定时器结束//或定时器被取消是调用,这时error_code值为boost::asio::error::operation_abortedstd::cout << "async is called" << std::endl;//注意不要直接使用本地(如2015-01-22 15:38:00)时间,否则要等待很长时间boost::posix_time::ptime pt2 = t.expires_at() + boost::posix_time::seconds(3);std::string abstime = boost::posix_time::to_simple_string(pt2);boost::asio::deadline_timer t2(io, boost::posix_time::time_from_string(abstime));//构造一个绝对定失效的定时器t2.async_wait(boost::bind(&print_posix_time_to_string, boost::asio::placeholders::error, pt2));t2.cancel();//取消定时器io.run();//异步操作必须调用run()}void handle_expriesfn(const boost::system::error_code& error, int flag){if (error != boost::asio::error::operation_aborted){flag ? (std::cout << "I have something to do..." << std::endl) : (std::cout << "I have nothing to do....." << std::endl);}else{std::cout << __FUNCTION__ << " handler is invalid" << std::endl;}}void on_some_event(boost::asio::deadline_timer& timer, int flag){//expires_from_now(relativetime)函数重新设置定时器时间,以前正在等待此定时器的handler都会被取消//返回被取消的handler个数(return The number of asynchronous operations that were cancelled)size_t cancelednum = timer.expires_from_now(boost::posix_time::seconds(2));if (cancelednum > 0){std::cout << "the cancelled handler is " << cancelednum << std::endl;timer.async_wait(boost::bind(handle_expriesfn, boost::asio::placeholders::error, flag));}else{std::cout << "too late, timer has expried" <<std::endl;}}void test_expries_from_now(){boost::asio::io_service io;boost::asio::deadline_timer t(io, boost::posix_time::seconds(2));t.async_wait(boost::bind(handle_expriesfn, boost::asio::placeholders::error, 0));t.async_wait(boost::bind(handle_expriesfn, boost::asio::placeholders::error, 1));on_some_event(t, 0);//取消定时器io.run();}void handler_cancel(const boost::system::error_code& error){if (error != boost::asio::error::operation_aborted){testSyncDT();}else{std::cout << __FUNCTION__ << " handler is invalid" << std::endl;}}void test_cancel(){boost::asio::io_service io;boost::asio::deadline_timer t(io, boost::posix_time::seconds(3));t.async_wait(boost::bind(handle_expriesfn, boost::asio::placeholders::error, 0));t.async_wait(handler_cancel);t.async_wait(boost::bind(handle_expriesfn, boost::asio::placeholders::error, 1));//boost::this_thread::sleep(boost::posix_time::seconds(3));boost::system::error_code err;t.cancel_one(err);//第一个handler会立即被调用error_code被置为boost::asio::error::operation_aborted,第二个handler在定时器结束时才被调用t.cancel_one(err);//注意这个地方io.run();}void on_any_event(boost::asio::deadline_timer& timer, int flag){//expires_at(abstime)函数重新设置定时器时间,以前正在等待此定时器的handler都会被取消//返回被取消的handler个数(return The number of asynchronous operations that were canceled)size_t cancelednum = timer.expires_at(timer.expires_at() + boost::posix_time::seconds(2));if (cancelednum > 0){std::cout << "the canceled handler is " << cancelednum << std::endl;timer.async_wait(boost::bind(handle_expriesfn, boost::asio::placeholders::error, flag));timer.async_wait(boost::bind(handle_expriesfn, boost::asio::placeholders::error, !flag));}else{std::cout << "too late, timer has expried" <<std::endl;}}void test_expires_at(){boost::asio::io_service io;boost::asio::deadline_timer t(io, boost::posix_time::seconds(2));t.async_wait(boost::bind(handle_expriesfn, boost::asio::placeholders::error, 0));t.async_wait(boost::bind(handle_expriesfn, boost::asio::placeholders::error, 1));on_any_event(t, 0);//取消定时器std::cout << t.expires_from_now() << std::endl;io.run();std::cout << t.expires_from_now() << std::endl;}main.cpp
#include "deadtime.h"void testTime(){//smtlTimer::testSyncDT();//smtlTimer::testAsyncDT();//smtlTimer::test_expries_from_now();smtlTimer::test_cancel();//smtlTimer::test_expires_at();}int main(){testTime();system("pause");return 0;}
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