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pgraph, resources: Integrate properly with the startup logic

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This signals which resources have to run their initial pokes, and
removes the racy retry timer. We actually get a proper signal when
things are running too!
This commit is contained in:
James Shubin
2016-12-20 04:29:14 -05:00
parent dd8d17232f
commit 0009d9b20e
3 changed files with 46 additions and 30 deletions
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48
pgraph/actions.go
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@@ -453,10 +453,26 @@ func (g *Graph) Worker(v *Vertex) error {
func (g *Graph) Start(first bool) { // start or continue
log.Printf("State: %v -> %v", g.setState(graphStateStarting), g.getState())
defer log.Printf("State: %v -> %v", g.setState(graphStateStarted), g.getState())
var wg sync.WaitGroup
t, _ := g.TopologicalSort()
// TODO: only calculate indegree if `first` is true to save resources
indegree := g.InDegree() // compute all of the indegree's
for _, v := range Reverse(t) {
// selective poke: here we reduce the number of initial pokes
// to the minimum required to activate every vertex in the
// graph, either by direct action, or by getting poked by a
// vertex that was previously activated. if we poke each vertex
// that has no incoming edges, then we can be sure to reach the
// whole graph. Please note: this may mask certain optimization
// failures, such as any poke limiting code in Poke() or
// BackPoke(). You might want to disable this selective start
// when experimenting with and testing those elements.
// if we are unpausing (since it's not the first run of this
// function) we need to poke to *unpause* every graph vertex,
// and not just selectively the subset with no indegree.
if (!first) || indegree[v] == 0 {
v.Res.Starter(true) // let the startup code know to poke
}
if !v.Res.IsWatching() { // if Watch() is not running...
g.wg.Add(1)
@@ -475,31 +491,15 @@ func (g *Graph) Start(first bool) { // start or continue
}(v)
}
// selective poke: here we reduce the number of initial pokes
// to the minimum required to activate every vertex in the
// graph, either by direct action, or by getting poked by a
// vertex that was previously activated. if we poke each vertex
// that has no incoming edges, then we can be sure to reach the
// whole graph. Please note: this may mask certain optimization
// failures, such as any poke limiting code in Poke() or
// BackPoke(). You might want to disable this selective start
// when experimenting with and testing those elements.
// if we are unpausing (since it's not the first run of this
// function) we need to poke to *unpause* every graph vertex,
// and not just selectively the subset with no indegree.
if (!first) || indegree[v] == 0 {
// ensure state is started before continuing on to next vertex
for !v.SendEvent(event.EventStart, true, false) {
if g.Flags.Debug {
// if SendEvent fails, we aren't up yet
log.Printf("%s[%s]: Retrying SendEvent(Start)", v.Kind(), v.GetName())
// sleep here briefly or otherwise cause
// a different goroutine to be scheduled
time.Sleep(1 * time.Millisecond)
}
}
}
// let the vertices run their startup code in parallel
wg.Add(1)
go func(vv *Vertex) {
defer wg.Done()
vv.Res.Started() // block until started
}(v)
}
wg.Wait() // wait for everyone
}
// Wait waits for all the graph vertex workers to exit.