Merge pull request #3 from ramr/start_entry_pt

Add a new entry point: Start which takes configuration

reaper.go

@@ -8,6 +8,10 @@ import "os"
 import "os/signal"
 import "syscall"
 
+type Config struct {
+	Pid     int
+	Options int
+}
 
 //  Handle death of child (SIGCHLD) messages. Pushes the signal onto the
 //  notifications channel if there is a waiter.
@@ -16,9 +20,9 @@ func sigChildHandler(notifications chan os.Signal) {
 	signal.Notify(sigs, syscall.SIGCHLD)
 
 	for {
-		var sig = <- sigs
+		var sig = <-sigs
 		select {
-		case notifications <-sig:  /*  published it.  */
+		case notifications <- sig: /*  published it.  */
 		default:
 			/*
 			 *  Notifications channel full - drop it to the
@@ -29,15 +33,17 @@ func sigChildHandler(notifications chan os.Signal) {
 		}
 	}
 
-}  /*  End of function  sigChildHandler.  */
-
+} /*  End of function  sigChildHandler.  */
 
 //  Be a good parent - clean up behind the children.
-func reapChildren() {
+func reapChildren(config Config) {
 	var notifications = make(chan os.Signal, 1)
 
 	go sigChildHandler(notifications)
 
+	pid := config.Pid
+	opts := config.Options
+
 	for {
 		var sig = <-notifications
 		fmt.Printf(" - Received signal %v\n", sig)
@@ -48,9 +54,9 @@ func reapChildren() {
 			 *  Reap 'em, so that zombies don't accumulate.
 			 *  Plants vs. Zombies!!
 			 */
-			pid, err := syscall.Wait4(-1, &wstatus, 0, nil)
+			pid, err := syscall.Wait4(pid, &wstatus, opts, nil)
 			for syscall.EINTR == err {
-				pid, err = syscall.Wait4(-1, &wstatus, 0, nil)
+				pid, err = syscall.Wait4(pid, &wstatus, opts, nil)
 			}
 
 			if syscall.ECHILD == err {
@@ -63,31 +69,46 @@ func reapChildren() {
 		}
 	}
 
-}  /*   End of function  reapChildren.  */
-
-
+} /*   End of function  reapChildren.  */
 
 /*
  *  ======================================================================
  *  Section: Exported functions
  *  ======================================================================
  */
 
-//  Entry point for the reaper code. Start reaping children in the
+//  Normal entry point for the reaper code. Start reaping children in the
 //  background inside a goroutine.
 func Reap() {
 	/*
 	 *  Only reap processes if we are taking over init's duties aka
 	 *  we are running as pid 1 inside a docker container.
 	 */
-	 if 1 == os.Getpid() {
-		 /*
-		  *  Ok, we are the grandma of 'em all, so we get to play
-		  *  the grim reaper.
-		  *  You will be missed, Terry Pratchett!! RIP
-		  */
-		  go reapChildren()
-	 }
+	if 1 == os.Getpid() {
+		config := Config{Pid: -1, Options: 0}
+
+		/*
+		 *  Ok, we are the grandma of 'em all, so we get to play
+		 *  the grim reaper.
+		 *  You will be missed, Terry Pratchett!! RIP
+		 */
+		go reapChildren(config)
+	}
+
+} /*  End of [exported] function  Reap.  */
 
-}  /*  End of [exported] function  Reap.  */
+//  Entry point for invoking the reaper code bypassing pid 1 checks and
+//  with a specific configuration. Starts reaping children in the background
+//  inside a goroutine.
+func Start(config Config) {
+	/*
+	 *  Start the Reaper with configuration options. This allows you to
+	 *  reap processes even if the current pid isn't running as pid 1.
+	 *  So ... use with caution!!
+	 *
+	 *  In most cases, you are better off just using Reap() as that
+	 *  checks if we are running as Pid 1.
+	 */
+	go reapChildren(config)
 
+} /*  End of [exported] function  Start.  */

test/.gitignore

@@ -0,0 +1 @@
+Dockerfile

test/Makefile

@@ -1,11 +1,17 @@
 #!/usr/bin/env make
 
+TEST_IMAGE = "reaper/test"
+CONFIG_TEST_IMAGE = "reaper/config-test"
+
 all:	tests
 
 test:	tests
 
 tests:
-	(go build testpid1.go; docker build -t reaper/test .; ./runtests.sh)
-
-
-
+	(go build testpid1.go;                       \
+	  cp docker-files/no-config/Dockerfile .;    \
+	  docker build -t $(TEST_IMAGE) .;           \
+	  ./runtests.sh;                             \
+	  cp docker-files/json-config/Dockerfile .;  \
+	  docker build -t $(CONFIG_TEST_IMAGE) .;    \
+	  ./runtests.sh "$(CONFIG_TEST_IMAGE)" )

test/config/reaper.json

@@ -0,0 +1,4 @@
+{
+	"Pid": 0,
+	"Options": 0
+}

test/runtests.sh

@@ -4,6 +4,8 @@
 readonly MAX_SLEEP_TIME=$((5 + 2))
 readonly IMAGE="reaper/test"
 
+logfile="/tmp/reaper_test.log"
+
 
 function get_sleepers() {
   ps -ef -p $1 | grep sleep | grep -v grep
@@ -32,14 +34,24 @@ function check_orphans() {
 
 
 function terminate_container() {
+    docker logs "$1" > "$logfile"
+    echo "  - Container logs saved to $logfile"
+
     echo "  - Terminated container $(docker rm -f "$1")"
 
 }  #  End of function  terminate_container.
 
 
 function run_tests() {
-  echo "  - Starting docker container running image $IMAGE ..."
-  local elcid=$(docker run -dit $IMAGE)
+  local image=${1:-"${IMAGE}"}
+
+  logfile="/tmp/$(echo ${image} | sed 's#/#_#g').log"
+
+  echo "  - Removing any existing log file $logfile ... "
+  rm -f "$logfile"
+
+  echo "  - Starting docker container running image ${image} ..."
+  local elcid=$(docker run -dit "${image}")
 
   echo "  - Docker container name=$elcid"
   local pid1=$(docker inspect --format '{{.State.Pid}}' $elcid)

test/testpid1.go

@@ -1,17 +1,53 @@
 package main
 
+import "encoding/json"
 import "fmt"
 import "os"
 import "os/signal"
 import "os/exec"
 import "path/filepath"
 import "syscall"
+import "time"
 
 import reaper "github.com/ramr/go-reaper"
 
+const NWORKERS = 3
+const REAPER_JSON_CONFIG = "/reaper/config/reaper.json"
 
-const NWORKERS=3
+func sleeper_test(set_proc_attributes bool) {
+	fmt.Printf(" - Set process attributes: %+v\n", set_proc_attributes)
 
+	cmd := exec.Command("sleep", "1")
+	if set_proc_attributes {
+		cmd.SysProcAttr = &syscall.SysProcAttr{
+			Setpgid: true,
+			Pgid:    0,
+		}
+	}
+
+	err := cmd.Start()
+	if err != nil {
+		fmt.Printf(" - Error starting sleep command: %s\n", err)
+		return
+	}
+
+	fmt.Printf("Set proc attributes: %+v\n", set_proc_attributes)
+
+	// Sleep for a wee bit longer to allow the reaper to reap the
+	// command on a slow system.
+	time.Sleep(4 * time.Second)
+
+	err = cmd.Wait()
+	if err != nil {
+		if set_proc_attributes {
+			fmt.Printf(" - Error waiting for command: %s\n",
+				err)
+		} else {
+			fmt.Printf(" - Expected wait failure: %s\n", err)
+		}
+	}
+
+} /*  End of function  sleeper_test.  */
 
 func start_workers() {
 	//  Starts up workers - which in turn start up kids that get
@@ -28,34 +64,58 @@ func start_workers() {
 		fmt.Printf(" - Error getting script - %s\n", scriptFile)
 		return
 	}
-	
+
 	var args = fmt.Sprintf("%d", NWORKERS)
 	var cmd = exec.Command(script, args)
 	cmd.Start()
 
 	fmt.Printf("  - Started worker: %s %s\n", script, args)
 
-}  /*  End of function  start_workers.  */
+} /*  End of function  start_workers.  */
 
+func main() {
+	sig := make(chan os.Signal, 1)
+	signal.Notify(sig, syscall.SIGUSR1)
+
+	useConfig := false
+	config := reaper.Config{}
+
+	configFile, err := os.Open(REAPER_JSON_CONFIG)
+	if err == nil {
+		decoder := json.NewDecoder(configFile)
+		err = decoder.Decode(&config)
+		if err == nil {
+			useConfig = true
+		} else {
+			fmt.Printf(" - Error: Invalid json config: %s", err)
+			fmt.Printf(" - Using defaults ... ")
+		}
+	}
 
+	/*  Start the grim reaper ... */
+	if useConfig {
+		go reaper.Start(config)
 
-func main() {
-  sig := make(chan os.Signal, 1)
-  signal.Notify(sig, syscall.SIGUSR1)
+		/*  Run the sleeper test setting the process attributes.  */
+		go sleeper_test(true)
 
-  /*  Start the grim reaper ... */
-  go reaper.Reap()
+		/*  And run test without setting process attributes.  */
+		go sleeper_test(false)
 
-  /*  Start the initial set of workers ... */
-  start_workers()
+	} else {
+		go reaper.Reap()
+	}
 
-  for {
-    select {
-    case <-sig:
-	fmt.Println("  - Got SIGUSR1, starting more workers ...")
+	/*  Start the initial set of workers ... */
 	start_workers()
-    }
 
-  }  /*  End of while doomsday ... */
+	for {
+		select {
+		case <-sig:
+			fmt.Println("  - Got SIGUSR1, adding workers ...")
+			start_workers()
+		}
+
+	} /*  End of while doomsday ... */
 
-}  /*  End of function  main.  */
+} /*  End of function  main.  */