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fix(solver) resolve a data race with ops counters #381

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merged 1 commit into from
May 21, 2021
Merged

fix(solver) resolve a data race with ops counters #381

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8 changes: 4 additions & 4 deletions cmd/common.go
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Original file line number Diff line number Diff line change
Expand Up @@ -166,14 +166,14 @@ func syncMain(ctx context.Context, filenames []string, dry bool, parallelism,
stats, errs := solver.Solve(ctx, s, wsClient, nil, parallelism, dry)
printFn := color.New(color.FgGreen, color.Bold).PrintfFunc()
printFn("Summary:\n")
printFn(" Created: %v\n", stats.CreateOps)
printFn(" Updated: %v\n", stats.UpdateOps)
printFn(" Deleted: %v\n", stats.DeleteOps)
printFn(" Created: %v\n", stats.CreateOps.Count())
printFn(" Updated: %v\n", stats.UpdateOps.Count())
printFn(" Deleted: %v\n", stats.DeleteOps.Count())
if errs != nil {
return utils.ErrArray{Errors: errs}
}
if diffCmdNonZeroExitCode &&
stats.CreateOps+stats.UpdateOps+stats.DeleteOps != 0 {
stats.CreateOps.Count()+stats.UpdateOps.Count()+stats.DeleteOps.Count() != 0 {
os.Exit(exitCodeDiffDetection)
}
return nil
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8 changes: 4 additions & 4 deletions cmd/common_konnect.go
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Original file line number Diff line number Diff line change
Expand Up @@ -90,14 +90,14 @@ func syncKonnect(ctx context.Context,
stats, errs := solver.Solve(ctx, s, kongClient, konnectClient, parallelism, dry)
printFn := color.New(color.FgGreen, color.Bold).PrintfFunc()
printFn("Summary:\n")
printFn(" Created: %v\n", stats.CreateOps)
printFn(" Updated: %v\n", stats.UpdateOps)
printFn(" Deleted: %v\n", stats.DeleteOps)
printFn(" Created: %v\n", stats.CreateOps.Count())
printFn(" Updated: %v\n", stats.UpdateOps.Count())
printFn(" Deleted: %v\n", stats.DeleteOps.Count())
if errs != nil {
return utils.ErrArray{Errors: errs}
}
if diffCmdNonZeroExitCode &&
stats.CreateOps+stats.UpdateOps+stats.DeleteOps != 0 {
stats.CreateOps.Count()+stats.UpdateOps.Count()+stats.DeleteOps.Count() != 0 {
os.Exit(exitCodeDiffDetection)
}

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36 changes: 29 additions & 7 deletions solver/solver.go
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Original file line number Diff line number Diff line change
Expand Up @@ -2,6 +2,7 @@ package solver

import (
"context"
"sync"

"github.com/kong/deck/crud"
"github.com/kong/deck/diff"
Expand All @@ -14,9 +15,26 @@ import (

// Stats holds the stats related to a Solve.
type Stats struct {
CreateOps int
UpdateOps int
DeleteOps int
CreateOps *AtomicInt32Counter
UpdateOps *AtomicInt32Counter
DeleteOps *AtomicInt32Counter
}

type AtomicInt32Counter struct {
counter int32
lock sync.RWMutex
}

func (a *AtomicInt32Counter) Increment(delta int32) {
a.lock.Lock()
defer a.lock.Unlock()
a.counter += delta
}

func (a *AtomicInt32Counter) Count() int32 {
a.lock.RLock()
defer a.lock.RUnlock()
return a.counter
}

// Solve generates a diff and walks the graph.
Expand All @@ -26,15 +44,19 @@ func Solve(ctx context.Context, syncer *diff.Syncer,

r := buildRegistry(client, konnectClient)

var stats Stats
stats := Stats{
CreateOps: &AtomicInt32Counter{},
UpdateOps: &AtomicInt32Counter{},
DeleteOps: &AtomicInt32Counter{},
}
recordOp := func(op crud.Op) {
switch op {
case crud.Create:
stats.CreateOps = stats.CreateOps + 1
stats.CreateOps.Increment(1)
case crud.Update:
stats.UpdateOps = stats.UpdateOps + 1
stats.UpdateOps.Increment(1)
case crud.Delete:
stats.DeleteOps = stats.DeleteOps + 1
stats.DeleteOps.Increment(1)
}
}

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23 changes: 23 additions & 0 deletions solver/solver_test.go
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Original file line number Diff line number Diff line change
@@ -0,0 +1,23 @@
package solver

import (
"sync"
"testing"

"github.com/stretchr/testify/assert"
)

func TestAtomicInt32Counter(t *testing.T) {
var a AtomicInt32Counter
var wg sync.WaitGroup

wg.Add(10)
for i := 0; i < 10; i++ {
go func() {
defer wg.Done()
a.Increment(int32(1))
}()
}
Comment on lines +15 to +20
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optional: too see any meaningful risk of race condition occuring, you probably need each of the goroutines to increment the counter 1000 times in a loop.

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This is really to trigger a data race bug with go test -race.
If we disable locking, this reliably produces the race:

go test -race
==================
WARNING: DATA RACE
Read at 0x00c000156240 by goroutine 9:
  github.com/kong/deck/solver.(*AtomicInt32Counter).Increment()
      /home/hbagdi/deck/solver/solver.go:31 +0x6f
  github.com/kong/deck/solver.TestStats_CreateOps.func1()
      /home/hbagdi/deck/solver/solver_test.go:18 +0x66

Previous write at 0x00c000156240 by goroutine 8:
  github.com/kong/deck/solver.(*AtomicInt32Counter).Increment()
      /home/hbagdi/deck/solver/solver.go:31 +0x84
  github.com/kong/deck/solver.TestStats_CreateOps.func1()
      /home/hbagdi/deck/solver/solver_test.go:18 +0x66

Goroutine 9 (running) created at:
  github.com/kong/deck/solver.TestStats_CreateOps()
      /home/hbagdi/deck/solver/solver_test.go:16 +0xf2
  testing.tRunner()
      /usr/local/go/src/testing/testing.go:1194 +0x202

Goroutine 8 (finished) created at:
  github.com/kong/deck/solver.TestStats_CreateOps()
      /home/hbagdi/deck/solver/solver_test.go:16 +0xf2
  testing.tRunner()
      /usr/local/go/src/testing/testing.go:1194 +0x202
==================
--- FAIL: TestStats_CreateOps (0.00s)
    testing.go:1093: race detected during execution of test
FAIL
exit status 1
FAIL    github.com/kong/deck/solver     0.008s

wg.Wait()
assert.Equal(t, int32(10), a.Count())
}