[#128]: fix: panic if there are no workers

.github/workflows/linters.yml

@@ -18,6 +18,6 @@ jobs:
       - name: Run linter
         uses: golangci/golangci-lint-action@v6.0.1 # Action page: <https://github.com/golangci/golangci-lint-action>
         with:
-          version: v1.57 # without patch version
+          version: v1.59 # without patch version
           only-new-issues: false # show only new issues if it's a pull request
           args: --timeout=10m --build-tags=race

.github/workflows/linux.yml

@@ -26,7 +26,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        php: ["8.2"]
+        php: ["8.3"]
         go: [stable]
         os: ["ubuntu-latest"]
     steps:

pool/static_pool/pool_test.go

@@ -178,7 +178,8 @@ func Test_StaticPool_RemoveWorker(t *testing.T) {
 	_, err = p.Exec(ctx, &payload.Payload{Body: []byte("hello"), Context: nil}, make(chan struct{}))
 	assert.NoError(t, err)
 
-	assert.Len(t, p.Workers(), 1)
+	// after removing all workers, we should have 1 worker + 1 we added
+	assert.Len(t, p.Workers(), 2)
 
 	p.Destroy(ctx)
 }

pool/static_pool/supervisor_test.go

@@ -174,7 +174,7 @@ func Test_SupervisedPool_RemoveNoWorkers(t *testing.T) {
 		assert.NoError(t, p.RemoveWorker(ctx))
 	}
 
-	assert.Len(t, p.Workers(), 0)
+	assert.Len(t, p.Workers(), 1)
 	p.Destroy(ctx)
 }
 
@@ -208,7 +208,7 @@ func Test_SupervisedPool_RemoveWorker(t *testing.T) {
 	_, err = p.Exec(ctx, &payload.Payload{Body: []byte("hello"), Context: nil}, make(chan struct{}))
 	assert.NoError(t, err)
 
-	assert.Len(t, p.Workers(), 1)
+	assert.Len(t, p.Workers(), 2)
 
 	p.Destroy(ctx)
 }

worker_watcher/worker_watcher.go

@@ -80,6 +80,12 @@ func (ww *WorkerWatcher) RemoveWorker(ctx context.Context) error {
 		return err
 	}
 
+	// can't remove the last worker
+	if atomic.LoadUint64(&ww.numWorkers) == 1 {
+		ww.log.Warn("can't remove the last worker", zap.Int64("pid", w.Pid()))
+		return nil
+	}
+
 	// destroy and stop
 	w.State().Transition(fsm.StateDestroyed)
 	_ = w.Stop()
@@ -403,6 +409,10 @@ func (ww *WorkerWatcher) wait(w *worker.Process) {
 	err = ww.Allocate()
 	if err != nil {
 		ww.log.Error("failed to allocate the worker", zap.String("internal_event_name", events.EventWorkerError.String()), zap.Error(err))
+		if atomic.LoadUint64(&ww.numWorkers) == 0 {
+			panic("no workers available, can't run the application")
+		}
+
 		return
 	}