sync master /w main

debounce_time.go

@@ -0,0 +1,75 @@
+// Copyright © 2024 Jon Friesen <[email protected]>.
+//
+// Use of this source code is governed by an MIT-style
+// license that can be found in the LICENSE file.
+
+package debounce
+
+import (
+	"sync"
+	"time"
+)
+
+var now = time.Now
+
+// NewDebounceByDuration returns a debounced function that takes another function as its argument.
+// This function will be called at the given interval, but no more than the max duration
+// from the first call.
+func NewDebounceByDuration(interval, maxDuration time.Duration) func(f func()) {
+	d := &durationDebouncer{
+		interval:    interval,
+		maxDuration: maxDuration,
+	}
+
+	return func(f func()) {
+		d.add(f)
+	}
+}
+
+type durationDebouncer struct {
+	mu          sync.Mutex
+	interval    time.Duration
+	maxDuration time.Duration
+	timer       *time.Timer
+	firstCall   bool
+	startTime   time.Time
+}
+
+func (d *durationDebouncer) add(f func()) {
+	d.mu.Lock()
+	defer d.mu.Unlock()
+
+	now := now()
+	if !d.firstCall {
+		d.firstCall = true
+		d.startTime = now
+	}
+
+	if d.timer != nil {
+		d.timer.Stop()
+	}
+
+	remainingDuration := d.maxDuration - time.Since(d.startTime)
+	if remainingDuration <= 0 {
+		d.reset()
+		f()
+		return
+	}
+
+	d.timer = time.AfterFunc(d.interval, func() {
+		d.mu.Lock()
+		defer d.mu.Unlock()
+
+		f()
+		d.reset()
+	})
+}
+
+func (d *durationDebouncer) reset() {
+	d.firstCall = false
+	if d.timer != nil {
+		d.timer.Stop()
+		d.timer = nil
+	}
+	d.startTime = time.Time{}
+}

debounce_time_test.go

@@ -0,0 +1,92 @@
+package debounce
+
+import (
+	"sync"
+	"testing"
+	"time"
+)
+
+var (
+	mockNowFunc  func() time.Time
+	mockNowMutex sync.Mutex
+)
+
+func mockNow() time.Time {
+	mockNowMutex.Lock()
+	defer mockNowMutex.Unlock()
+	return mockNowFunc()
+}
+
+func setMockNow(t time.Time) {
+	mockNowMutex.Lock()
+	defer mockNowMutex.Unlock()
+	mockNowFunc = func() time.Time {
+		return t
+	}
+}
+
+func init() {
+	now = mockNow
+}
+
+func TestTimeDebounce(t *testing.T) {
+	tests := []struct {
+		name        string
+		interval    time.Duration
+		maxDuration time.Duration
+		timeSteps   []time.Duration
+	}{
+		{
+			name:        "Single call within interval",
+			interval:    100 * time.Millisecond,
+			maxDuration: 500 * time.Millisecond,
+			timeSteps:   []time.Duration{100 * time.Millisecond, 50 * time.Millisecond},
+		},
+		{
+			name:        "Multiple calls within interval",
+			interval:    100 * time.Millisecond,
+			maxDuration: 500 * time.Millisecond,
+			timeSteps:   []time.Duration{50 * time.Millisecond, 50 * time.Millisecond, 200 * time.Millisecond},
+		},
+		{
+			name:        "Single call at max duration",
+			interval:    100 * time.Millisecond,
+			maxDuration: 200 * time.Millisecond,
+			timeSteps:   []time.Duration{100 * time.Millisecond, 100 * time.Millisecond},
+		},
+		{
+			name:        "Multiple calls at max duration",
+			interval:    150 * time.Millisecond,
+			maxDuration: 300 * time.Millisecond,
+			timeSteps:   []time.Duration{50 * time.Millisecond, 50 * time.Millisecond, 200 * time.Millisecond},
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			callCount := 0
+			mu := sync.Mutex{}
+			f := func() {
+				mu.Lock()
+				defer mu.Unlock()
+				callCount++
+			}
+
+			d := NewDebounceByDuration(tt.interval, tt.maxDuration)
+			start := time.Now()
+			setMockNow(start)
+
+			for _, step := range tt.timeSteps {
+				setMockNow(start.Add(step))
+				d(f)
+				time.Sleep(step)
+			}
+
+			mu.Lock()
+			if callCount != 1 {
+				t.Errorf("expected 1 calls, got %d", callCount)
+			}
+			mu.Unlock()
+		})
+	}
+}