From e7bf70c3e001d35721d23e300df68fcebb4276df Mon Sep 17 00:00:00 2001
From: Sherif Abdel-Naby <sherifabdlnaby@gmail.com>
Date: Sat, 3 Apr 2021 06:43:16 +0200
Subject: [PATCH] Job Wrapper / Add RMutex Locks

Signed-off-by: Sherif Abdel-Naby <sherifabdlnaby@gmail.com>
---
 job/error.go                 | 14 ++++++-------
 job/{interface.go => job.go} | 40 +++++++++++++++++++++++++++++-------
 2 files changed, 40 insertions(+), 14 deletions(-)
 rename job/{interface.go => job.go} (61%)

diff --git a/job/error.go b/job/error.go
index 77462d8..e6b6814 100644
--- a/job/error.go
+++ b/job/error.go
@@ -1,17 +1,17 @@
-package Job
+package job
 
 type ErrorJobPanic struct {
-	Name string
+	Message string
 }
 
 func (e ErrorJobPanic) Error() string {
-	return e.Name
+	return e.Message
 }
 
-type ErrorJobNotStarted struct {
-	Name string
+type ErrorJobStarted struct {
+	Message string
 }
 
-func (e ErrorJobNotStarted) Error() string {
-	return e.Name
+func (e ErrorJobStarted) Error() string {
+	return e.Message
 }
diff --git a/job/interface.go b/job/job.go
similarity index 61%
rename from job/interface.go
rename to job/job.go
index 9414411..a7325e5 100644
--- a/job/interface.go
+++ b/job/job.go
@@ -1,12 +1,13 @@
-package Job
+package job
 
 import (
 	"fmt"
 	"github.com/google/uuid"
+	"sync"
 	"time"
 )
 
-type State int
+type State int64
 
 const (
 	NEW State = iota
@@ -22,6 +23,11 @@ type Job struct {
 	startTime  time.Time
 	finishTime time.Time
 	state      State
+	mx         sync.RWMutex
+}
+
+func (j *Job) State() State {
+	return j.state
 }
 
 func NewJobWithID(id string, jobFunc func()) *Job {
@@ -43,14 +49,17 @@ func (j *Job) ID() string {
 	return j.id
 }
 
-func (j *Job) Duration() (time.Duration, error) {
+func (j *Job) Duration() time.Duration {
+	j.mx.RLock()
+	defer j.mx.RUnlock()
+
 	if !j.startTime.IsZero() {
 		if j.finishTime.IsZero() {
-			return time.Since(j.startTime), nil
+			return time.Since(j.startTime)
 		}
-		return j.finishTime.Sub(j.startTime), nil
+		return j.finishTime.Sub(j.startTime)
 	}
-	return -1, fmt.Errorf("job hasn't started yet")
+	return -1
 }
 
 func (j *Job) Start() error {
@@ -58,20 +67,37 @@ func (j *Job) Start() error {
 }
 
 func (j *Job) start() (err error) {
+	j.mx.RLock()
+	if j.state != NEW {
+		if j.state == STARTED {
+			err = ErrorJobStarted{Message: "job already started"}
+			return err
+		}
+		err = ErrorJobStarted{Message: "job finished execution"}
+		return err
+	}
+	j.mx.RUnlock()
+
+	j.mx.Lock()
 	j.state = STARTED
 	j.startTime = time.Now()
 
 	// Handle Panics and set correct state
 	defer func() {
+		j.mx.Lock()
 		if r := recover(); r != nil {
-			err = fmt.Errorf("job panicked: %v", r)
+			err = ErrorJobPanic{Message: fmt.Sprintf("job panicked: %v", r)}
 			j.state = PANICKED
 		} else {
 			j.state = FINISHED
 		}
 		j.finishTime = time.Now()
+		j.mx.Unlock()
 	}()
 
+	// Unlock State
+	j.mx.Unlock()
+
 	// Start Job
 	j.jobFunc()