From 6e176034306026b922c1df4231a1807f36cbe460 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Paul=20B=C3=BCtow?= <pbuetow@mimecast.com>
Date: Sat, 22 Feb 2020 12:06:09 +0000
Subject: can start commands in background and also cancel those via drun
 command

---
 internal/server/background/background.go | 52 +++++++++++++++-----------------
 1 file changed, 24 insertions(+), 28 deletions(-)

(limited to 'internal/server/background/background.go')

diff --git a/internal/server/background/background.go b/internal/server/background/background.go
index 537ccbb..05a502f 100644
--- a/internal/server/background/background.go
+++ b/internal/server/background/background.go
@@ -2,10 +2,8 @@ package background
 
 import (
 	"context"
-	"fmt"
+	"errors"
 	"sync"
-
-	"github.com/mimecast/dtail/internal/io/logger"
 )
 
 type job struct {
@@ -13,27 +11,44 @@ type job struct {
 	done   <-chan struct{}
 }
 
+// Background specifies a job or command run in background on server side.
+// This does not require an active DTail client SSH connection/session.
 type Background struct {
-	mutex sync.Mutex
+	mutex *sync.Mutex
 	jobs  map[string]job
 }
 
-func NewBackground() *Background {
-	return &Background{
-		jobs: make(map[string]job),
+// New returns a new background manager.
+func New() Background {
+	return Background{
+		jobs:  make(map[string]job),
+		mutex: &sync.Mutex{},
 	}
 }
 
+// Add a background job.
 func (b Background) Add(name string, cancel context.CancelFunc, done <-chan struct{}) error {
 	b.mutex.Lock()
 	defer b.mutex.Unlock()
 
 	if _, ok := b.jobs[name]; ok {
-		return fmt.Errorf("job '%s' already exists", name)
+		return errors.New("job already exists")
 	}
 
-	logger.Debug("background", name, "adding job")
 	b.jobs[name] = job{cancel, done}
+	return nil
+}
+
+// Cancel a background job.
+func (b Background) Cancel(name string) error {
+	job, ok := b.get(name)
+	if !ok {
+		return errors.New("no job to cancel")
+	}
+
+	job.cancel()
+	<-job.done
+	b.delete(name)
 
 	return nil
 }
@@ -52,22 +67,3 @@ func (b Background) delete(name string) {
 
 	delete(b.jobs, name)
 }
-
-func (b Background) Stop(name string) {
-	logger.Debug("background", name, "stopping job")
-	job, ok := b.get(name)
-
-	if !ok {
-		logger.Debug("background", name, "no such job")
-		return
-	}
-
-	logger.Debug("background", name, "canceling job")
-	job.cancel()
-
-	logger.Debug("background", name, "waiting for job to complete")
-	<-job.done
-
-	logger.Debug("background", name, "deleting job")
-	b.delete(name)
-}
-- 
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