2 files changed, 163 insertions, 0 deletions
diff --git a/src/go/collectors/go.d.plugin/agent/filelock/filelock.go b/src/go/collectors/go.d.plugin/agent/filelock/filelock.go
new file mode 100644
index 000000000..f266e0102
--- /dev/null
+++ b/src/go/collectors/go.d.plugin/agent/filelock/filelock.go
@@ -0,0 +1,64 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+package filelock
+
+import (
+	"path/filepath"
+
+	"github.com/gofrs/flock"
+)
+
+func New(dir string) *Locker {
+	return &Locker{
+		suffix: ".collector.lock",
+		dir:    dir,
+		locks:  make(map[string]*flock.Flock),
+	}
+}
+
+type Locker struct {
+	suffix string
+	dir    string
+	locks  map[string]*flock.Flock
+}
+
+func (l *Locker) Lock(name string) (bool, error) {
+	filename := l.filename(name)
+
+	if _, ok := l.locks[filename]; ok {
+		return true, nil
+	}
+
+	locker := flock.New(filename)
+
+	ok, err := locker.TryLock()
+	if ok {
+		l.locks[filename] = locker
+	} else {
+		_ = locker.Close()
+	}
+
+	return ok, err
+}
+
+func (l *Locker) Unlock(name string) {
+	filename := l.filename(name)
+
+	locker, ok := l.locks[filename]
+	if !ok {
+		return
+	}
+
+	delete(l.locks, filename)
+
+	_ = locker.Close()
+}
+
+func (l *Locker) isLocked(name string) bool {
+	_, ok := l.locks[l.filename(name)]
+	return ok
+}
+
+func (l *Locker) filename(name string) string {
+	return filepath.Join(l.dir, name+l.suffix)
+}
diff --git a/src/go/collectors/go.d.plugin/agent/filelock/filelock_test.go b/src/go/collectors/go.d.plugin/agent/filelock/filelock_test.go
new file mode 100644
index 000000000..6ffc794ec
--- /dev/null
+++ b/src/go/collectors/go.d.plugin/agent/filelock/filelock_test.go
@@ -0,0 +1,99 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+package filelock
+
+import (
+	"os"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestNew(t *testing.T) {
+	assert.NotNil(t, New(""))
+}
+
+func TestLocker_Lock(t *testing.T) {
+	tests := map[string]func(t *testing.T, dir string){
+		"register a lock": func(t *testing.T, dir string) {
+			reg := New(dir)
+
+			ok, err := reg.Lock("name")
+			assert.True(t, ok)
+			assert.NoError(t, err)
+		},
+		"register the same lock twice": func(t *testing.T, dir string) {
+			reg := New(dir)
+
+			ok, err := reg.Lock("name")
+			require.True(t, ok)
+			require.NoError(t, err)
+
+			ok, err = reg.Lock("name")
+			assert.True(t, ok)
+			assert.NoError(t, err)
+		},
+		"failed to register locked by other process lock": func(t *testing.T, dir string) {
+			reg1 := New(dir)
+			reg2 := New(dir)
+
+			ok, err := reg1.Lock("name")
+			require.True(t, ok)
+			require.NoError(t, err)
+
+			ok, err = reg2.Lock("name")
+			assert.False(t, ok)
+			assert.NoError(t, err)
+		},
+		"failed to register because a directory doesnt exist": func(t *testing.T, dir string) {
+			reg := New(dir + dir)
+
+			ok, err := reg.Lock("name")
+			assert.False(t, ok)
+			assert.Error(t, err)
+		},
+	}
+
+	for name, test := range tests {
+		t.Run(name, func(t *testing.T) {
+			dir, err := os.MkdirTemp(os.TempDir(), "netdata-go-test-file-lock-registry")
+			require.NoError(t, err)
+			defer func() { require.NoError(t, os.RemoveAll(dir)) }()
+
+			test(t, dir)
+		})
+	}
+}
+
+func TestLocker_Unlock(t *testing.T) {
+	tests := map[string]func(t *testing.T, dir string){
+		"unregister a lock": func(t *testing.T, dir string) {
+			reg := New(dir)
+
+			ok, err := reg.Lock("name")
+			require.True(t, ok)
+			require.NoError(t, err)
+			reg.Unlock("name")
+
+			assert.False(t, reg.isLocked("name"))
+		},
+		"unregister not registered lock": func(t *testing.T, dir string) {
+			reg := New(dir)
+
+			reg.Unlock("name")
+
+			assert.False(t, reg.isLocked("name"))
+		},
+	}
+
+	for name, test := range tests {
+		t.Run(name, func(t *testing.T) {
+			dir, err := os.MkdirTemp(os.TempDir(), "netdata-go-test-file-lock-registry")
+			require.NoError(t, err)
+			defer func() { require.NoError(t, os.RemoveAll(dir)) }()
+
+			test(t, dir)
+		})
+	}
+}