1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
|
// Copyright (C) 2019-2024 Algorand, Inc.
// This file is part of go-algorand
//
// go-algorand is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as
// published by the Free Software Foundation, either version 3 of the
// License, or (at your option) any later version.
//
// go-algorand is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with go-algorand. If not, see <https://www.gnu.org/licenses/>.
package merklearray
import (
"runtime"
"sync"
"sync/atomic"
)
// workerState describes a group of goroutines processing a sequential list
// of maxidx elements starting from 0.
type workerState struct {
// maxidx is the total number of elements to process, and nextidx
// is the next element that a worker should process.
maxidx uint64
nextidx atomic.Uint64
// nworkers is the number of workers that can be started.
// This field gets decremented once workers are launched,
// and represents the number of remaining workers that can
// be launched.
nworkers int
// starting is a channel that paces the creation of workers.
// In particular, a new worker can be started only when the
// previous worker starts running code. The first thing that
// a worker does is to send a message on this channel, to allow
// for more workers to start. This ensures reasonable performance
// even when the number of elements to process is small (and where
// otherwise the cost of launching workers might dominate).
starting chan struct{}
// wg tracks outstanding workers, to determine when all workers
// have finished their processing.
wg sync.WaitGroup
}
func newWorkerState(max uint64) *workerState {
var ws workerState
ws.nworkers = runtime.NumCPU()
ws.maxidx = max
ws.starting = make(chan struct{}, 1)
ws.starting <- struct{}{}
return &ws
}
// next returns the next position to process, and bumps the counter
// by delta. This implicitly means that the worker that calls next
// is promising to process delta elements at the returned position.
func (ws *workerState) next(delta uint64) uint64 {
return ws.nextidx.Add(delta) - delta
}
// wait waits for all of the workers to finish.
func (ws *workerState) wait() {
ws.wg.Wait()
}
// nextWorker() is used by the top-level caller to decide when it
// should launch the next worker.
func (ws *workerState) nextWorker() bool {
if ws.nworkers <= 0 {
return false
}
_ = <-ws.starting
curidx := ws.nextidx.Load()
if curidx >= ws.maxidx {
return false
}
ws.nworkers--
ws.wg.Add(1)
return true
}
// When a worker thread starts running, it can call started() to
// allow the next worker thread to be spawned.
func (ws *workerState) started() {
ws.starting <- struct{}{}
}
|
