From 291ef6a536f05678d1fbddc6071194fe9ce65b97 Mon Sep 17 00:00:00 2001
From: Harry Bagdi <harrybagdi@gmail.com>
Date: Fri, 21 May 2021 13:48:24 -0700
Subject: [PATCH] fix(solver) resolve a data race with ops counters

---
 cmd/common.go         |  8 ++++----
 cmd/common_konnect.go |  8 ++++----
 solver/solver.go      | 36 +++++++++++++++++++++++++++++-------
 solver/solver_test.go | 23 +++++++++++++++++++++++
 4 files changed, 60 insertions(+), 15 deletions(-)
 create mode 100644 solver/solver_test.go

diff --git a/cmd/common.go b/cmd/common.go
index b482dca8c..f758afa65 100644
--- a/cmd/common.go
+++ b/cmd/common.go
@@ -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
diff --git a/cmd/common_konnect.go b/cmd/common_konnect.go
index 37aa493f7..2d375bf98 100644
--- a/cmd/common_konnect.go
+++ b/cmd/common_konnect.go
@@ -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)
 	}
 
diff --git a/solver/solver.go b/solver/solver.go
index 6d71e8136..c308f351d 100644
--- a/solver/solver.go
+++ b/solver/solver.go
@@ -2,6 +2,7 @@ package solver
 
 import (
 	"context"
+	"sync"
 
 	"github.com/kong/deck/crud"
 	"github.com/kong/deck/diff"
@@ -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.
@@ -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)
 		}
 	}
 
diff --git a/solver/solver_test.go b/solver/solver_test.go
new file mode 100644
index 000000000..427b96504
--- /dev/null
+++ b/solver/solver_test.go
@@ -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))
+		}()
+	}
+	wg.Wait()
+	assert.Equal(t, int32(10), a.Count())
+}