commit 2869941b0c3891f06e1da9226ce498c160ea6d41
Author: Jeremy Tregunna <jeremy@tregunna.ca>
Date:   Thu Dec 26 01:03:17 2024 -0600

    feat: Initial task execution system

diff --git a/go.mod b/go.mod
new file mode 100644
index 0000000..484444c
--- /dev/null
+++ b/go.mod
@@ -0,0 +1,3 @@
+module git.canoozie.net/jer/task
+
+go 1.23.2
diff --git a/task.go b/task.go
new file mode 100644
index 0000000..1082eda
--- /dev/null
+++ b/task.go
@@ -0,0 +1,95 @@
+package task
+
+import (
+	"log"
+	"time"
+)
+
+type Task interface {
+	Execute() error
+}
+
+type ScheduledTask struct {
+	task        Task
+	interval    time.Duration
+	lastRunTime time.Time
+}
+
+type TaskExecutor struct {
+	tasks     []*ScheduledTask
+	rateLimit chan struct{}
+	taskChan  chan *ScheduledTask
+}
+
+func NewTaskExecutor(rateLimit int) *TaskExecutor {
+	return &TaskExecutor{
+		rateLimit: make(chan struct{}, rateLimit),
+		taskChan:  make(chan *ScheduledTask, 100),
+	}
+}
+
+func (te *TaskExecutor) Len() int {
+	return len(te.tasks)
+}
+
+func (te *TaskExecutor) AddTask(task Task, interval time.Duration) {
+	log.Printf("Adding task %T with interval %v\n", task, interval)
+	st := &ScheduledTask{
+		task:        task,
+		interval:    interval,
+		lastRunTime: time.Now(),
+	}
+
+	select {
+	case te.taskChan <- st:
+		log.Printf("Task %T queued up with interval %v\n", task, interval)
+	default:
+		log.Printf("Failed to add task $T with interval %v, channel full\n", task, interval)
+	}
+}
+
+func (te *TaskExecutor) Start() {
+	go func() {
+		for {
+			select {
+			case st := <-te.taskChan:
+				te.tasks = append(te.tasks, st)
+				if st.interval == 0 {
+					log.Printf("Task %T has an interval of 0, running now\n", st.task)
+					go func(st *ScheduledTask) {
+						te.executeTask(st)
+					}(st)
+				} else if st.interval < 0 {
+					log.Printf("Task %T has a negative interval, nonsensical, ignoring", st.task)
+				} else {
+					go func(st *ScheduledTask) {
+						ticker := time.NewTicker(st.interval)
+						defer ticker.Stop()
+						for t := range ticker.C {
+							if !te.shouldRun(st, t) {
+								continue
+							}
+							st.lastRunTime = t
+							log.Printf("Task %T last run time: %v, running now\n", st.task, st.lastRunTime)
+							go te.executeTask(st)
+						}
+					}(st)
+				}
+			}
+		}
+	}()
+}
+
+func (te *TaskExecutor) shouldRun(st *ScheduledTask, t time.Time) bool {
+	return t.Sub(st.lastRunTime) >= st.interval
+}
+
+func (te *TaskExecutor) executeTask(st *ScheduledTask) {
+	te.rateLimit <- struct{}{}
+	defer func() {
+		<-te.rateLimit
+	}()
+	if err := st.task.Execute(); err != nil {
+		log.Printf("Task %v failed: %v", st.task, err)
+	}
+}
diff --git a/task_test.go b/task_test.go
new file mode 100644
index 0000000..b374bdf
--- /dev/null
+++ b/task_test.go
@@ -0,0 +1,137 @@
+package task
+
+import (
+	"errors"
+	"testing"
+	"time"
+)
+
+type mockTask struct {
+	executeFunc func() error
+}
+
+func (m *mockTask) Execute() error {
+	return m.executeFunc()
+}
+func TestAddTask(t *testing.T) {
+	te := NewTaskExecutor(10)
+	te.AddTask(&mockTask{}, 1*time.Second)
+	if te.Len() != 1 {
+		t.Errorf("expected 1 task, got %d", te.Len())
+	}
+}
+func TestExecuteTaskSuccess(t *testing.T) {
+	te := NewTaskExecutor(10)
+	executeCalled := false
+	te.AddTask(&mockTask{
+		executeFunc: func() error {
+			executeCalled = true
+			return nil
+		},
+	}, 50*time.Millisecond)
+	te.Start()
+	time.Sleep(200 * time.Millisecond)
+	if !executeCalled {
+		t.Error("expected execute to be called, but it was not")
+	}
+}
+func TestExecuteTaskFailure(t *testing.T) {
+	expectedError := errors.New("task failed")
+	te := NewTaskExecutor(10)
+	executeCalled := false
+	te.AddTask(&mockTask{
+		executeFunc: func() error {
+			executeCalled = true
+			return expectedError
+		},
+	}, 50*time.Millisecond)
+	te.Start()
+	time.Sleep(200 * time.Millisecond)
+	if !executeCalled {
+		t.Error("expected execute to be called, but it was not")
+	}
+}
+func TestRateLimit(t *testing.T) {
+	te := NewTaskExecutor(1)
+	for i := 0; i < 5; i++ {
+		delay := time.Duration(i) * time.Millisecond
+		te.AddTask(&mockTask{
+			executeFunc: func() error {
+				return nil
+			},
+		}, delay)
+	}
+	te.Start()
+	done := make(chan struct{})
+	go func() {
+		close(done)
+	}()
+	select {
+	case <-time.After(200 * time.Millisecond):
+		t.Error("expected all tasks to be executed within 200ms, but they were not")
+	case <-done:
+		// test passed
+	}
+}
+func TestZeroInterval(t *testing.T) {
+	te := NewTaskExecutor(10)
+	executeCalled := false
+	te.AddTask(&mockTask{
+		executeFunc: func() error {
+			executeCalled = true
+			return nil
+		},
+	}, 0*time.Second)
+	te.Start()
+	time.Sleep(50 * time.Millisecond)
+	if !executeCalled {
+		t.Error("expected execute to be called, but it was not")
+	}
+}
+func TestNoTasks(t *testing.T) {
+	te := NewTaskExecutor(10)
+	te.Start()
+	time.Sleep(50 * time.Millisecond)
+	// test passed if no panic occurred
+}
+
+var ErrorTask = errors.New("task failed")
+var executeTaskTestCases = []struct {
+	name          string
+	executeError  error
+	expectedError error
+}{
+	{
+		name:          "success",
+		executeError:  nil,
+		expectedError: nil,
+	},
+	{
+		name:          "failure",
+		executeError:  ErrorTask,
+		expectedError: ErrorTask,
+	},
+}
+
+func TestExecuteTask(t *testing.T) {
+	for _, tc := range executeTaskTestCases {
+		t.Run(tc.name, func(t *testing.T) {
+			te := NewTaskExecutor(10)
+			executeCalled := false
+			te.AddTask(&mockTask{
+				executeFunc: func() error {
+					executeCalled = true
+					return tc.executeError
+				},
+			}, 50*time.Millisecond)
+			te.Start()
+			time.Sleep(200 * time.Millisecond)
+			if !executeCalled {
+				t.Fatal("expected execute to be called, but it was not")
+			}
+			if tc.expectedError != nil && !errors.Is(tc.expectedError, tc.executeError) {
+				t.Errorf("expected error '%+v', got '%+v'", tc.expectedError, tc.executeError)
+			}
+		})
+	}
+}