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// This module defines the Context type, which carries deadlines, cancellation signals,
// and other request-scoped values across API boundaries and between processes.
// Based off: https://github.com/golang/go/tree/master/src/context
// Last commit: https://github.com/golang/go/commit/52bf14e0e8bdcd73f1ddfb0c4a1d0200097d3ba2
module context
import rand
import time
// A TimerContext carries a timer and a deadline. It embeds a CancelContext to
// implement done and err. It implements cancel by stopping its timer then
// delegating to CancelContext.cancel
pub struct TimerContext {
id string
mut:
cancel_ctx CancelContext
deadline time.Time
}
// with_deadline returns a copy of the parent context with the deadline adjusted
// to be no later than d. If the parent's deadline is already earlier than d,
// with_deadline(parent, d) is semantically equivalent to parent. The returned
// context's Done channel is closed when the deadline expires, when the returned
// cancel function is called, or when the parent context's Done channel is
// closed, whichever happens first.
//
// Canceling this context releases resources associated with it, so code should
// call cancel as soon as the operations running in this Context complete.
pub fn with_deadline(parent Context, d time.Time) Context {
id := rand.uuid_v4()
if cur := parent.deadline() {
if cur < d {
// The current deadline is already sooner than the new one.
return with_cancel(parent)
}
}
cancel_ctx := new_cancel_context(parent)
mut ctx := &TimerContext{
cancel_ctx: cancel_ctx
deadline: d
id: id
}
propagate_cancel(parent, mut ctx)
dur := d - time.now()
if dur.nanoseconds() <= 0 {
ctx.cancel(true, deadline_exceeded) // deadline has already passed
return Context(ctx)
}
if ctx.err() is none {
go fn (mut ctx TimerContext, dur time.Duration) {
time.sleep(dur)
ctx.cancel(true, deadline_exceeded)
}(mut ctx, dur)
}
return Context(ctx)
}
// with_timeout returns with_deadline(parent, time.now().add(timeout)).
//
// Canceling this context releases resources associated with it, so code should
// call cancel as soon as the operations running in this Context complete
pub fn with_timeout(parent Context, timeout time.Duration) Context {
return with_deadline(parent, time.now().add(timeout))
}
pub fn (ctx TimerContext) deadline() ?time.Time {
return ctx.deadline
}
pub fn (mut ctx TimerContext) done() chan int {
return ctx.cancel_ctx.done()
}
pub fn (mut ctx TimerContext) err() IError {
return ctx.cancel_ctx.err()
}
pub fn (ctx TimerContext) value(key string) ?voidptr {
return ctx.cancel_ctx.value(key)
}
pub fn (mut ctx TimerContext) cancel(remove_from_parent bool, err IError) {
ctx.cancel_ctx.cancel(false, err)
if remove_from_parent {
// Remove this TimerContext from its parent CancelContext's children.
remove_child(ctx.cancel_ctx.context, ctx)
}
}
pub fn (ctx TimerContext) str() string {
return context_name(ctx.cancel_ctx.context) + '.with_deadline(' + ctx.deadline.str() + ' [' +
(time.now() - ctx.deadline).str() + '])'
}
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