v/vlib/sync/waitgroup.v

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// Copyright (c) 2019 Alexander Medvednikov. All rights reserved.
// Use of this source code is governed by an MIT license
// that can be found in the LICENSE file.
module sync
struct WaitGroup {
mut:
mu Mutex
finished Mutex
active int
}
pub fn (wg mut WaitGroup) add(delta int) {
wg.mu.lock()
if wg.active == 0 {
wg.finished.lock()
}
wg.active += delta
if wg.active < 0 {
panic('Negative number of jobs in waitgroup')
}
if wg.active == 0 {
wg.finished.unlock()
}
wg.mu.unlock()
}
pub fn (wg mut WaitGroup) done() {
wg.add(-1)
}
pub fn (wg mut WaitGroup) wait() {
wg.finished.lock()
wg.finished.unlock()
}