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