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World imports

Import interface wasi:io/[email protected]

A poll API intended to let users wait for I/O events on multiple handles at once.

Types

resource pollable

pollable represents a single I/O event which may be ready, or not.

Functions

[method]pollable.ready: func

Return the readiness of a pollable. This function never blocks.

Returns true when the pollable is ready, and false otherwise.

Params
Return values
  • bool

[method]pollable.block: func

block returns immediately if the pollable is ready, and otherwise blocks until ready.

This function is equivalent to calling poll.poll on a list containing only this pollable.

Params

poll: func

Poll for completion on a set of pollables.

This function takes a list of pollables, which identify I/O sources of interest, and waits until one or more of the events is ready for I/O.

The result list<u32> contains one or more indices of handles in the argument list that is ready for I/O.

This function traps if either:

  • the list is empty, or:
  • the list contains more elements than can be indexed with a u32 value.

A timeout can be implemented by adding a pollable from the wasi-clocks API to the list.

This function does not return a result; polling in itself does not do any I/O so it doesn't fail. If any of the I/O sources identified by the pollables has an error, it is indicated by marking the source as being ready for I/O.

Params
Return values
  • list<u32>

Import interface wasi:clocks/[email protected]

WASI Monotonic Clock is a clock API intended to let users measure elapsed time.

It is intended to be portable at least between Unix-family platforms and Windows.

A monotonic clock is a clock which has an unspecified initial value, and successive reads of the clock will produce non-decreasing values.

Types

type pollable

pollable

#### `type instant` `u64`

An instant in time, in nanoseconds. An instant is relative to an unspecified initial value, and can only be compared to instances from the same monotonic-clock.

type duration

u64

A duration of time, in nanoseconds.

Functions

now: func

Read the current value of the clock.

The clock is monotonic, therefore calling this function repeatedly will produce a sequence of non-decreasing values.

Return values

resolution: func

Query the resolution of the clock. Returns the duration of time corresponding to a clock tick.

Return values

subscribe-instant: func

Create a pollable which will resolve once the specified instant has occurred.

Params
Return values

subscribe-duration: func

Create a pollable that will resolve after the specified duration has elapsed from the time this function is invoked.

Params
Return values

Import interface wasi:clocks/[email protected]

WASI Wall Clock is a clock API intended to let users query the current time. The name "wall" makes an analogy to a "clock on the wall", which is not necessarily monotonic as it may be reset.

It is intended to be portable at least between Unix-family platforms and Windows.

A wall clock is a clock which measures the date and time according to some external reference.

External references may be reset, so this clock is not necessarily monotonic, making it unsuitable for measuring elapsed time.

It is intended for reporting the current date and time for humans.

Types

record datetime

A time and date in seconds plus nanoseconds.

Record Fields
  • seconds: u64
  • nanoseconds: u32

Functions

now: func

Read the current value of the clock.

This clock is not monotonic, therefore calling this function repeatedly will not necessarily produce a sequence of non-decreasing values.

The returned timestamps represent the number of seconds since 1970-01-01T00:00:00Z, also known as POSIX's Seconds Since the Epoch, also known as Unix Time.

The nanoseconds field of the output is always less than 1000000000.

Return values

resolution: func

Query the resolution of the clock.

The nanoseconds field of the output is always less than 1000000000.

Return values

Import interface wasi:clocks/[email protected]

Types

type datetime

datetime

#### `record timezone-display`

Information useful for displaying the timezone of a specific datetime.

This information may vary within a single timezone to reflect daylight saving time adjustments.

Record Fields

  • utc-offset: s32

    The number of seconds difference between UTC time and the local time of the timezone.

    The returned value will always be less than 86400 which is the number of seconds in a day (246060).

    In implementations that do not expose an actual time zone, this should return 0.

  • name: string

    The abbreviated name of the timezone to display to a user. The name `UTC` indicates Coordinated Universal Time. Otherwise, this should reference local standards for the name of the time zone.

    In implementations that do not expose an actual time zone, this should be the string UTC.

    In time zones that do not have an applicable name, a formatted representation of the UTC offset may be returned, such as -04:00.

  • in-daylight-saving-time: bool

    Whether daylight saving time is active.

    In implementations that do not expose an actual time zone, this should return false.

Functions

display: func

Return information needed to display the given datetime. This includes the UTC offset, the time zone name, and a flag indicating whether daylight saving time is active.

If the timezone cannot be determined for the given datetime, return a timezone-display for UTC with a utc-offset of 0 and no daylight saving time.

Params
Return values

utc-offset: func

The same as display, but only return the UTC offset.

Params
Return values
  • s32