/
executiongroup.go
187 lines (156 loc) · 4.02 KB
/
executiongroup.go
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package ecsgo
import (
"context"
"slices"
"sync"
"time"
"github.com/pkg/errors"
"golang.org/x/sync/errgroup"
)
type executionGroup struct {
executeList []*System
depRootNode *depTreeNode
dirty bool
}
func newExecutionGroup() *executionGroup {
return &executionGroup{}
}
func (e *executionGroup) addSystem(sys *System) *executionGroup {
e.dirty = true
e.executeList = append(e.executeList, sys)
return e
}
// dependent node
type depNode struct {
sys *System
edges []*depNode
}
func (e *executionGroup) build() error {
if !e.dirty {
return nil
}
e.dirty = false
slices.SortFunc(e.executeList, func(a, b *System) int {
if a.GetPriority() == b.GetPriority() {
return b.getInterestComponentCount() - a.getInterestComponentCount()
}
return a.GetPriority() - b.GetPriority()
})
// make dependency graph
nodes := make([]*depNode, len(e.executeList))
for i, sys := range e.executeList {
nodes[i] = &depNode{sys: sys}
}
// double loop to make dependency graph
for i := 0; i < len(nodes); i++ {
for j := i + 1; j < len(nodes); j++ {
if nodes[i].sys.dependent(nodes[j].sys) {
nodes[i].edges = append(nodes[i].edges, nodes[j])
}
}
}
// change dependency graph to dependency tree
var err error
e.depRootNode, err = changeToDependencyTree(nodes)
return errors.Errorf("failed to change to dependency tree: %v", err)
}
// dependency tree node
type depTreeNode struct {
sys *System
waitCount int
wg sync.WaitGroup
edges []*depTreeNode
}
func (n *depTreeNode) addEdge(edge *depTreeNode) {
edge.wg.Add(1)
edge.waitCount++
n.edges = append(n.edges, edge)
}
func changeToDependencyTree(nodes []*depNode) (*depTreeNode, error) {
root := &depTreeNode{}
resolved := make(map[*depNode]bool)
depNodeMap := make(map[*depNode]*depTreeNode)
for {
if len(nodes) == 0 {
return root, nil
}
unresolved := make(map[*depNode]bool)
leastDepNode, err := depResolve(nodes[0], resolved, unresolved)
if err != nil {
return nil, errors.Errorf("failed to resolve dependency: %v", err)
}
treeNode := &depTreeNode{
sys: leastDepNode.sys,
}
depNodeMap[leastDepNode] = treeNode
// inverse node
if len(leastDepNode.edges) == 0 {
root.addEdge(treeNode)
} else {
for _, edge := range leastDepNode.edges {
edgeTreeNode := depNodeMap[edge]
edgeTreeNode.addEdge(treeNode)
}
}
// remove leastDepNode from node list
nodes = slices.DeleteFunc(nodes, func(n *depNode) bool {
return n == leastDepNode
})
}
}
func depResolve(node *depNode, resolved, unresolved map[*depNode]bool) (*depNode, error) {
unresolved[node] = true
for _, edge := range node.edges {
if !resolved[edge] {
if unresolved[edge] {
return nil, errors.Errorf("circular dependency detected: %v -> %v", node.sys, edge.sys)
}
return depResolve(edge, resolved, unresolved)
}
}
resolved[node] = true
delete(unresolved, node)
return node, nil
}
func (e *executionGroup) execute(deltaTime time.Duration, ctx context.Context) error {
err := e.build()
if err != nil {
return errors.Errorf("failed to build dependency tree %v", err)
}
errs, ctx := errgroup.WithContext(ctx)
err = runTree(e.depRootNode, deltaTime, &sync.Map{}, errs, ctx)
if err != nil {
return errors.Errorf("failed to run dependency tree %v", err)
}
return errs.Wait()
}
// runTree - run dependency tree parallely
func runTree(node *depTreeNode, deltaTime time.Duration, visited *sync.Map, errs *errgroup.Group, ctx context.Context) error {
if ctx.Err() != nil {
return ctx.Err()
}
node.wg.Wait()
// reset wait group count for next round
node.wg.Add(node.waitCount)
var err error
if node.sys != nil {
err = node.sys.execute(deltaTime)
}
for _, edge := range node.edges {
edge.wg.Done()
}
// shold return error after edge node waitGroup done for not starving edge
if err != nil {
return err
}
for _, edge := range node.edges {
_, loaded := visited.LoadOrStore(edge, true)
if !loaded {
e := edge
errs.Go(func() error {
return runTree(e, deltaTime, visited, errs, ctx)
})
}
}
return nil
}