From 5137bd3a1d8c851d3c13fa3aaa1d468dde555333 Mon Sep 17 00:00:00 2001
From: Ian Davis <nospam@iandavis.com>
Date: Tue, 27 Oct 2020 12:17:36 +0000
Subject: [PATCH] feat: make delay between tasks configurable

---
 commands/run.go       | 10 +++++++++-
 schedule/scheduler.go | 15 +++++++++++----
 2 files changed, 20 insertions(+), 5 deletions(-)

diff --git a/commands/run.go b/commands/run.go
index fca05a1a3..5dc5672e6 100644
--- a/commands/run.go
+++ b/commands/run.go
@@ -209,6 +209,14 @@ var Run = &cli.Command{
 			Usage:   "Lease time for the chain economics processor",
 			EnvVars: []string{"VISOR_CHAINECONOMICS_LEASE"},
 		},
+
+		&cli.DurationFlag{
+			Name:    "task-delay",
+			Aliases: []string{"td"},
+			Value:   500 * time.Millisecond,
+			Usage:   "Base time to wait between starting tasks (jitter is added)",
+			EnvVars: []string{"VISOR_TASK_DELAY"},
+		},
 	},
 	Action: func(cctx *cli.Context) error {
 		// Validate flags
@@ -246,7 +254,7 @@ var Run = &cli.Command{
 			}
 		}()
 
-		scheduler := schedule.NewScheduler()
+		scheduler := schedule.NewScheduler(cctx.Duration("task-delay"))
 
 		// Add one indexing task to follow the chain head
 		if cctx.Bool("indexhead") {
diff --git a/schedule/scheduler.go b/schedule/scheduler.go
index f53b17828..dcbd1a235 100644
--- a/schedule/scheduler.go
+++ b/schedule/scheduler.go
@@ -46,12 +46,19 @@ type Locker interface {
 	Unlock(context.Context) error
 }
 
-func NewScheduler() *Scheduler {
-	return &Scheduler{}
+func NewScheduler(taskDelay time.Duration) *Scheduler {
+	// Enforce a minimum delay
+	if taskDelay == 0 {
+		taskDelay = 100 * time.Millisecond
+	}
+	return &Scheduler{
+		taskDelay: taskDelay,
+	}
 }
 
 type Scheduler struct {
-	tasks []TaskConfig
+	tasks     []TaskConfig
+	taskDelay time.Duration
 }
 
 // Add add a task config to the scheduler. This must not be called after Run.
@@ -147,7 +154,7 @@ func (s *Scheduler) Run(ctx context.Context) error {
 		default:
 		}
 		// A little jitter between tasks to reduce thundering herd effects on api
-		wait.SleepWithJitter(500*time.Millisecond, 2)
+		wait.SleepWithJitter(s.taskDelay, 2)
 	}
 
 	// Wait until the context is done or all tasks have been completed