102 lines
2.2 KiB
Go
102 lines
2.2 KiB
Go
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// Copyright 2018 The Periph Authors. All rights reserved.
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// Use of this source code is governed under the Apache License, Version 2.0
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// that can be found in the LICENSE file.
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// This file contains the parallelized driver loading logic. It is meant to be
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// load the drivers as fast as possible by parallelising work.
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// +build !tinygo
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package periph
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import (
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"errors"
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"strconv"
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"sync"
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)
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func initImpl() (*State, error) {
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state = &State{}
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// At this point, byName is guaranteed to be immutable.
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cD := make(chan Driver)
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cS := make(chan DriverFailure)
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cE := make(chan DriverFailure)
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var wg sync.WaitGroup
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wg.Add(1)
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go func() {
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defer wg.Done()
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for d := range cD {
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state.Loaded = insertDriver(state.Loaded, d)
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}
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}()
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wg.Add(1)
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go func() {
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defer wg.Done()
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for f := range cS {
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state.Skipped = insertDriverFailure(state.Skipped, f)
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}
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}()
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wg.Add(1)
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go func() {
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defer wg.Done()
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for f := range cE {
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state.Failed = insertDriverFailure(state.Failed, f)
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}
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}()
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stages, err := explodeStages()
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if err != nil {
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return state, err
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}
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loaded := make(map[string]struct{}, len(byName))
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for _, s := range stages {
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s.loadParallel(loaded, cD, cS, cE)
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}
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close(cD)
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close(cS)
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close(cE)
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wg.Wait()
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return state, nil
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}
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// loadParallel loads all the drivers for this stage in parallel.
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//
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// Updates loaded in a safe way.
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func (s *stage) loadParallel(loaded map[string]struct{}, cD chan<- Driver, cS, cE chan<- DriverFailure) {
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success := make(chan string)
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go func() {
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defer close(success)
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wg := sync.WaitGroup{}
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loop:
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for name, drv := range s.drvs {
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// Intentionally do not look at After(), only Prerequisites().
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for _, dep := range drv.Prerequisites() {
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if _, ok := loaded[dep]; !ok {
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cS <- DriverFailure{drv, errors.New("dependency not loaded: " + strconv.Quote(dep))}
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continue loop
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}
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}
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// Not skipped driver, attempt loading in a goroutine.
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wg.Add(1)
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go func(n string, d Driver) {
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defer wg.Done()
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if ok, err := d.Init(); ok {
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if err == nil {
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cD <- d
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success <- n
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return
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}
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cE <- DriverFailure{d, err}
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} else {
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cS <- DriverFailure{d, err}
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}
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}(name, drv)
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}
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wg.Wait()
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}()
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for s := range success {
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loaded[s] = struct{}{}
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}
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}
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