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resources: Fix poke/refresh race

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Clearly the use of errgroup is flawed.
1) You can't pass in variables, so this is likely to race.
2) You can't get a set of errors, so this is a bad API.

For the second problem, it would be much more sane to return a multierr
or a list of errors. If there's no fix for the first, I think it should
be removed from the lib.
This commit is contained in:
James Shubin
2016-12-04 20:33:36 -05:00
parent 639afe881c
commit 07fd2e88a2
2 changed files with 15 additions and 12 deletions
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25
pgraph/actions.go
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@@ -29,7 +29,6 @@ import (
"github.com/purpleidea/mgmt/resources"
errwrap "github.com/pkg/errors"
"golang.org/x/sync/errgroup"
)
// GetTimestamp returns the timestamp of a vertex
@@ -65,7 +64,7 @@ func (g *Graph) OKTimestamp(v *Vertex) bool {
// Poke notifies nodes after me in the dependency graph that they need refreshing...
// NOTE: this assumes that this can never fail or need to be rescheduled
func (g *Graph) Poke(v *Vertex, activity bool) error {
var eg errgroup.Group
var wg sync.WaitGroup
// these are all the vertices pointing AWAY FROM v, eg: v -> ???
for _, n := range g.OutgoingGraphVertices(v) {
// XXX: if we're in state event and haven't been cancelled by
@@ -75,17 +74,17 @@ func (g *Graph) Poke(v *Vertex, activity bool) error {
if global.DEBUG {
log.Printf("%s[%s]: Poke: %s[%s]", v.Kind(), v.GetName(), n.Kind(), n.GetName())
}
//wg.Add(1)
eg.Go(func() error {
//defer wg.Done()
edge := g.Adjacency[v][n] // lookup
wg.Add(1)
go func(nn *Vertex) error {
defer wg.Done()
edge := g.Adjacency[v][nn] // lookup
notify := edge.Notify && edge.Refresh()
// FIXME: is it okay that this is sync?
n.SendEvent(event.EventPoke, true, notify)
nn.SendEvent(event.EventPoke, true, notify)
// TODO: check return value?
return nil // never error for now...
})
}(n)
} else {
if global.DEBUG {
@@ -93,7 +92,8 @@ func (g *Graph) Poke(v *Vertex, activity bool) error {
}
}
}
return eg.Wait() // wait for all the pokes to complete
wg.Wait() // wait for all the pokes to complete
return nil
}
// BackPoke pokes the pre-requisites that are stale and need to run before I can run.
@@ -218,8 +218,11 @@ func (g *Graph) Process(v *Vertex) error {
// if CheckApply ran without noop and without error, state should be good
if !noop && err == nil { // aka !noop || checkOK
obj.StateOK(true) // reset
g.SetUpstreamRefresh(v, false) // refresh happened, clear the request
obj.StateOK(true) // reset
if refresh {
g.SetUpstreamRefresh(v, false) // refresh happened, clear the request
obj.SetRefresh(false)
}
}
if !checkOK { // if state *was* not ok, we had to have apply'ed