I read the code again and find my mistake. The actual relationship is as follows: * `basic_deadline_timer` is the i/o object type, one instance for each deadline_timer; * `deadline_timer_service` is the service type, one per `io_service`, retrieved by the constructor of `basic_io_object`; * `detail::deadline_timer_service` is the service implementation type, one per service, hen one per `io_serive` as well. It is defined as the data member of `deadline_timer_service`; * `detail::deadline_timer_service::implementation_type`: the implementation type of the timer, one per `deadline_timer`. As `timer_queue_` is a member of `detail::deadline_timer_service`, it is one per `io_service` as well. Looks reasonable for me now. The highscore link seems have merged the service implementation type and timer implementation type into one, which is a bit misleading. Thanks. Danqi On Sun, Nov 16, 2014 at 12:58 AM, Bjorn Reese <breese@mail1.stofanet.dk> wrote:
On 11/15/2014 04:24 PM, Wang Danqi wrote:
There will be a single instance of `deadline_timer_service` serving many `deadline_timer` objects. An instance of `detail::deadline_timer_service` is created for each `deadline_timer` object.
All the deadline_timer objects obtain a pointer to the same detail::deadline_time_service (via the basic_io_object constructor) so there is at most one instance per io_service.
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-- Best wishes, Wang Danqi