/
chan.go
69 lines (63 loc) · 1.8 KB
/
chan.go
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// Copyright 2023 The glassdb Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package concurr
// MakeChainInfCap simulates a channel with infinite capacity. This will never
// block the sender and grow an internal buffer if necessary.
//
// Close the input channel when finished, to free resources.
func MakeChanInfCap[T any](expectedCap int) (<-chan T, chan<- T) {
in := make(chan T, expectedCap)
out := make(chan T, expectedCap)
var queue []T
go func() {
loop:
for {
// Nothing to output here. We need to wait for some input.
v, ok := <-in
if !ok {
// We're closing. Just exit (the queue is empty).
break loop
}
// Try to push the element directly to the out chan.
// If it's full, push it to the queue instead.
select {
case out <- v:
continue loop
default:
queue = append(queue, v)
}
// Here we have something in the queue.
for len(queue) > 0 {
select {
case v, ok := <-in:
if !ok {
// We're closing. Consume the whole queue and exit.
for _, e := range queue {
out <- e
}
break loop
}
queue = append(queue, v)
case out <- queue[0]:
var empty T
queue[0] = empty // Avoid possible leaks.
queue = queue[1:]
}
}
}
// Signal the end of things.
close(out)
}()
return out, in
}