Expand description
Utilities for tracking time and constructing system timers.
§Futures
This module contains the following Futures:
Sleep, a future which completes after a specified duration,Timeout, which wraps anotherFutureto limit the duration it can run for.
§Timers
The Sleep and Timeout futures do not complete on their own. Instead,
they must be driven by a Timer, which tracks the current time and
notifies time-based futures when their deadlines are reached.
The Timer struct implements a hierarchical timer wheel, a data
structure for tracking large numbers of timers efficiently. It is used to
create Sleeps and Timeouts, and notify them when their deadlines
complete. In order to be used, a Timer must be driven by a hardware time
source. See the Timer documentation for more information
on using this type to implement a system timer.
§Global Timers
In most cases, it is desirable to have a single global timer instance that
drives all time-based futures in the system. In particular, creating new
Sleep and Timeout futures typically requires a reference to a
Timer instance, which can be inconvenient to pass around to the points
in a system where Sleep and Timeout futures are created.
Therefore, the maitake timer also includes support for setting a global
timer, using the set_global_timer function. Once a global timer
has been initialized, the sleep() and timeout() free functions in
this module can be used to create time-based futures without a reference to a
Timer instance. These functions will always create futures bound to the
global default timer.
Note that a global default timer can only be set once. Subsequent calls to
set_global_timer after a global timer has been initialized will
return an error.
Modules§
- clock
Clocks provide a mechanism for tracking the current time.- timeout
Timeouts limit the amount of time aFutureis allowed to run before it completes.
Structs§
- Already
Initialized - Errors returned by
set_global_timer. - Clock
- A hardware clock definition.
- Duration
- A
Durationtype to represent a span of time, typically used for system timeouts. - Instant
- A measurement of a monotonically nondecreasing
Clock. Opaque and useful only withDuration. - Sleep
- A
Futurethat completes after a specifiedDuration. - Timeout
- A
Futurethat requires an innerFutureto complete within a specifiedDuration. - Timer
- A
Timertracks the current time, and notifiesSleepandTimeoutfutures when they complete. - Turn
- Represents a single turn of the timer wheel.
Enums§
- Timer
Error - Errors returned by
Timer::try_sleep,Timer::try_timeout, and the globaltry_sleepandtry_timeoutfunctions.
Functions§
- set_
global_ timer - Sets a
Timeras the global default timer. - sleep
- Returns a
Futurethat completes after the specifiedDuration. - timeout
- Requires the provided
Futureto complete before the specifiedDurationhas elapsed. - try_
sleep - Returns a
Futurethat completes after the specifiedDuration. - try_
timeout - Requires the provided
Futureto complete before the specifiedDurationhas elapsed.