From f9c0a309b9e788f71173e9f931ac49496cba79ff Mon Sep 17 00:00:00 2001
From: Mike Crute <mike@crute.us>
Date: Sat, 21 May 2022 13:16:31 -0700
Subject: service: support init jobs

---
 service/app_runner.go | 29 ++++++++++++++++++++++++++++-
 1 file changed, 28 insertions(+), 1 deletion(-)

diff --git a/service/app_runner.go b/service/app_runner.go
index 99ae263..e1eb98b 100644
--- a/service/app_runner.go
+++ b/service/app_runner.go
@@ -2,6 +2,7 @@ package service
 
 import (
 	"context"
+	"fmt"
 	"os"
 	"os/signal"
 	"sync"
@@ -10,12 +11,15 @@ import (
 
 type AppRunnerLogger interface {
 	Info(...interface{})
+	Error(...interface{})
 }
 
+type SyncRunnerFunc func() error
 type RunnerFunc func(context.Context, *sync.WaitGroup) error
 
 type AppRunner struct {
 	Logger         AppRunnerLogger
+	initJobs       []SyncRunnerFunc
 	jobs           []RunnerFunc
 	backgroundJobs []RunnerFunc
 	wg             *sync.WaitGroup
@@ -26,6 +30,7 @@ type AppRunner struct {
 
 func NewAppRunner(ctx context.Context, logger AppRunnerLogger) *AppRunner {
 	r := &AppRunner{
+		initJobs:       []SyncRunnerFunc{},
 		jobs:           []RunnerFunc{},
 		backgroundJobs: []RunnerFunc{},
 		wg:             &sync.WaitGroup{},
@@ -42,6 +47,16 @@ func NewAppRunner(ctx context.Context, logger AppRunnerLogger) *AppRunner {
 	return r
 }
 
+func (r *AppRunner) AddInitJob(f SyncRunnerFunc) {
+	r.initJobs = append(r.initJobs, f)
+}
+
+func (r *AppRunner) AddInitJobs(jobs []SyncRunnerFunc) {
+	for _, j := range jobs {
+		r.AddInitJob(j)
+	}
+}
+
 func (r *AppRunner) AddJob(f RunnerFunc) {
 	r.jobs = append(r.jobs, f)
 }
@@ -56,7 +71,7 @@ func (r *AppRunner) AddBackgroundJob(f RunnerFunc) {
 	r.backgroundJobs = append(r.backgroundJobs, f)
 }
 
-func (r *AppRunner) goRunPanic(f func(context.Context, *sync.WaitGroup) error) {
+func (r *AppRunner) goRunPanic(f RunnerFunc) {
 	errs := make(chan error)
 	go func() { errs <- f(r.ctx, r.wg) }()
 	select {
@@ -67,6 +82,18 @@ func (r *AppRunner) goRunPanic(f func(context.Context, *sync.WaitGroup) error) {
 }
 
 func (r *AppRunner) RunForever(enableBg bool) {
+	// Init jobs must run before main jobs start, the should return on
+	// success but will panic on error
+	r.Logger.Info("Starting initialization jobs")
+	for _, f := range r.initJobs {
+		if err := f(); err != nil {
+			r.Logger.Error(fmt.Sprintf("Init job failed: %s", err))
+			return
+		}
+	}
+	r.Logger.Info("Initialization jobs finished")
+
+	r.Logger.Info("Starting main jobs")
 	for _, f := range r.jobs {
 		r.goRunPanic(f)
 	}
-- 
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