Atomic counters (#168)

Author: kawpii

internal/exercises/catalog.yaml

@@ -229,7 +229,15 @@ concepts:
     - Close the jobs channel after sending all work to signal workers to finish.
     - Use strings.TrimSpace() to clean message strings by removing leading/trailing whitespace.
     - Collect exactly len(logs) results to ensure all work is processed.
-    
+- slug: 44_atomic_counters
+  title: Atomic Counters
+  test_regex: ".*"
+  hints:
+    - Use `sync/atomic` package to create and increment atomic counter.
+    - Launch 10,000 anonymous go routines that simultaneously increment the counter.
+    - Use WaitGroups to wait for all go routines to finish. 
+
+
 projects:
 - slug: 101_text_analyzer
   title: Text Analyzer (Easy)

internal/exercises/solutions/44_atomic_counters/atomic_counters.go

@@ -0,0 +1,22 @@
+package atomic_counters
+
+import (
+	"sync"
+	"sync/atomic"
+)
+
+func NoRequestsProcessed() uint64 {
+
+	var ops atomic.Uint64
+	var wg sync.WaitGroup
+
+	wg.Add(10_000)
+	for range 10_000 {
+		go func() {
+			defer wg.Done()
+			ops.Add(1)
+		}()
+	}
+	wg.Wait()
+	return ops.Load()
+}

internal/exercises/templates/44_atomic_counters/atomic_counters.go

@@ -0,0 +1,9 @@
+package atomic_counters
+
+// TODO: Assume you have to keep track of the number of requests processed
+// by an applications to display on a dashboard.
+// 1. Launch 10_000 goroutines that increment a counter.
+//  2. Wait for all goroutines to finish and return the final value of the counter.
+func NoRequestsProcessed() uint64 {
+	return 0
+}

internal/exercises/templates/44_atomic_counters/atomic_counters_test.go

@@ -0,0 +1,14 @@
+package atomic_counters
+
+import "testing"
+
+func TestAtomicCounter(t *testing.T) {
+
+	t.Run("Counter values is correct!", func(t *testing.T) {
+		got := NoRequestsProcessed()
+		want := 10_000
+		if int(got) != want {
+			t.Fatalf("Got %d, want %d", got, want)
+		}
+	})
+}