Enum TimeService

pub enum TimeService {
    RealTimeService(RealTimeService),
}

TimeService abstracts all time-related operations in one place that can be easily mocked-out and controlled in tests or delegated to the actual underlying runtime (usually tokio). It’s provided as an enum so we don’t have to infect everything with a generic tag.

TimeService is async-focused: the sleep, interval, and timeout methods all return Futures and Streams. That said, TimeService supports non-async clients as well; simply use the sleep_blocking method instead of sleep. Note that the blocking call will actually block the current thread until the sleep time has elapsed.

TimeService tries to mirror the API provided by tokio::time to an extent. The primary difference is that all time is expressed in relative Durations. In other words, “sleep for 5s” vs “sleep until unix time 1607734460”. Absolute time is provided by TimeService::now which returns the current unix time.

Note: you must also include the TimeServiceTrait to use the actual time-related functionality.

Note: we have to provide our own Timeout and Interval types that use the Sleep future, since tokio’s implementations are coupled to its internal Sleep future.

Note: TimeService’s should be free (or very cheap) to clone and send around between threads. In production (without test features), this enum is a zero-sized type.

Variants

RealTimeService(RealTimeService)

Implementations

impl TimeService

pub fn real() -> Self

Create a new real, production time service that actually uses the systemtime.

See RealTimeService.

Trait Implementations

impl Clone for TimeService

fn clone(&self) -> TimeService

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for TimeService

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for TimeService

fn default() -> Self

Returns the “default value” for a type.

impl From<RealTimeService> for TimeService

fn from(v: RealTimeService) -> TimeService

Converts to this type from the input type.

impl TimeServiceTrait for TimeService

fn now(&self) -> Instant

Query a monotonically nondecreasing clock. Returns an opaque type that can only be compared to other Instants, i.e., this is a monotonic relative time whereas now_unix_time is a non-monotonic absolute time.

On Linux, this is equivalent to clock_gettime(CLOCK_MONOTONIC, _)

See Instant for more details.

fn now_unix_time(&self) -> Duration

Query the current unix timestamp as a Duration.

When used on a TimeService::real(), this is equivalent to SystemTime::now().duration_since(SystemTime::UNIX_EPOCH).

Note: the Duration returned from this function is NOT guaranteed to be monotonic. Use now if you need monotonicity.

From the SystemTime docs:

Distinct from the Instant type, this time measurement is not monotonic. This means that you can save a file to the file system, then save another file to the file system, and the second file has a SystemTime measurement earlier than the first. In other words, an operation that happens after another operation in real time may have an earlier SystemTime!

For example, the system administrator could clock_settime into the past, breaking clock time monotonicity.

On Linux, this is equivalent to clock_gettime(CLOCK_REALTIME, _).

fn now_secs(&self) -> u64

Query the current unix timestamp in seconds.

Equivalent to self.now_unix_time().as_secs(). See now_unix_time.

fn sleep_blocking(&self, __enum_dispatch_arg_0: Duration)

Blocks the current thread until duration time has passed.

impl TryInto<RealTimeService> for TimeService

type Error = &'static str

The type returned in the event of a conversion error.

fn try_into( self, ) -> Result<RealTimeService, <Self as TryInto<RealTimeService>>::Error>

Performs the conversion.