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v/vlib/context/onecontext/onecontext.v
2023-06-04 18:12:52 +02:00

147 lines
3.0 KiB
V

module onecontext
import context
import sync
import time
// canceled is the error returned when the cancel function is called on a merged context
pub const canceled = error('canceled context')
struct OneContext {
mut:
ctx context.Context
ctxs []context.Context
done chan int
err IError = none
err_mutex sync.Mutex
cancel_fn context.CancelFn
cancel_ctx context.Context
}
// merge allows to merge multiple contexts
// it returns the merged context
pub fn merge(ctx context.Context, ctxs ...context.Context) (context.Context, context.CancelFn) {
mut background := context.background()
cancel_ctx, cancel := context.with_cancel(mut &background)
mut octx := &OneContext{
done: chan int{cap: 3}
ctx: ctx
ctxs: ctxs
cancel_fn: cancel
cancel_ctx: cancel_ctx
}
spawn octx.run()
return context.Context(octx), context.CancelFn(cancel)
}
pub fn (octx OneContext) deadline() ?time.Time {
mut min := time.Time{}
if deadline := octx.ctx.deadline() {
min = deadline
}
for ctx in octx.ctxs {
if deadline := ctx.deadline() {
if min.unix_time() == 0 || deadline < min {
min = deadline
}
}
}
if min.unix_time() == 0 {
return none
}
return min
}
pub fn (octx OneContext) done() chan int {
return octx.done
}
pub fn (mut octx OneContext) err() IError {
octx.err_mutex.@lock()
defer {
octx.err_mutex.unlock()
}
return octx.err
}
pub fn (octx OneContext) value(key context.Key) ?context.Any {
if value := octx.ctx.value(key) {
return value
}
for ctx in octx.ctxs {
if value := ctx.value(key) {
return value
}
}
return none
}
pub fn (mut octx OneContext) run() {
mut wrapped_ctx := &octx.ctx
if octx.ctxs.len == 1 {
mut first_ctx := &octx.ctxs[0]
octx.run_two_contexts(mut wrapped_ctx, mut first_ctx)
return
}
octx.run_multiple_contexts(mut wrapped_ctx)
for mut ctx in octx.ctxs {
octx.run_multiple_contexts(mut ctx)
}
}
pub fn (octx OneContext) str() string {
return ''
}
pub fn (mut octx OneContext) cancel(err IError) {
octx.cancel_fn()
octx.err_mutex.@lock()
octx.err = err
octx.err_mutex.unlock()
if !octx.done.closed {
octx.done <- 0
octx.done.close()
}
}
pub fn (mut octx OneContext) run_two_contexts(mut ctx1 context.Context, mut ctx2 context.Context) {
spawn fn (mut octx OneContext, mut ctx1 context.Context, mut ctx2 context.Context) {
octx_cancel_done := octx.cancel_ctx.done()
c1done := ctx1.done()
c2done := ctx2.done()
select {
_ := <-octx_cancel_done {
octx.cancel(onecontext.canceled)
}
_ := <-c1done {
octx.cancel(ctx1.err())
}
_ := <-c2done {
octx.cancel(ctx1.err())
}
}
}(mut &octx, mut &ctx1, mut &ctx2)
}
pub fn (mut octx OneContext) run_multiple_contexts(mut ctx context.Context) {
spawn fn (mut octx OneContext, mut ctx context.Context) {
octx_cancel_done := octx.cancel_ctx.done()
cdone := ctx.done()
select {
_ := <-octx_cancel_done {
octx.cancel(onecontext.canceled)
}
_ := <-cdone {
octx.cancel(ctx.err())
}
}
}(mut &octx, mut &ctx)
}