[3/4] incubator-trafficcontrol git commit: Change TM2 log to Close old on Init

[ne...@apache.org]

Change TM2 log to Close old on Init

This allows changing the log location on the fly, without having
nightmarish synchronization issues.


Project: http://git-wip-us.apache.org/repos/asf/incubator-trafficcontrol/repo
Commit: http://git-wip-us.apache.org/repos/asf/incubator-trafficcontrol/commit/240043f5
Tree: http://git-wip-us.apache.org/repos/asf/incubator-trafficcontrol/tree/240043f5
Diff: http://git-wip-us.apache.org/repos/asf/incubator-trafficcontrol/diff/240043f5

Branch: refs/heads/master
Commit: 240043f56195e10acb6497f659296f2befd39af6
Parents: a7bdd08
Author: Robert Butts <ro...@gmail.com>
Authored: Wed Mar 29 14:23:44 2017 -0600
Committer: David Neuman <da...@gmail.com>
Committed: Wed Apr 19 15:31:43 2017 -0600

----------------------------------------------------------------------
 traffic_monitor_golang/common/log/log.go        | 50 +++++++++++++++-----
 .../traffic_monitor/traffic_monitor.go          | 10 ++--
 2 files changed, 44 insertions(+), 16 deletions(-)
----------------------------------------------------------------------


http://git-wip-us.apache.org/repos/asf/incubator-trafficcontrol/blob/240043f5/traffic_monitor_golang/common/log/log.go
----------------------------------------------------------------------
diff --git a/traffic_monitor_golang/common/log/log.go b/traffic_monitor_golang/common/log/log.go
index b3b567b..12d3082 100644
--- a/traffic_monitor_golang/common/log/log.go
+++ b/traffic_monitor_golang/common/log/log.go
@@ -28,19 +28,37 @@ import (
 )
 
 var (
-	Debug   *log.Logger
-	Info    *log.Logger
-	Warning *log.Logger
-	Error   *log.Logger
-	Event   *log.Logger
+	Debug       *log.Logger
+	Info        *log.Logger
+	Warning     *log.Logger
+	Error       *log.Logger
+	Event       *log.Logger
+	debugCloser io.Closer
+	infoCloser  io.Closer
+	warnCloser  io.Closer
+	errCloser   io.Closer
+	eventCloser io.Closer
 )
 
-func Init(eventW, errW, warnW, infoW, debugW io.Writer) {
-	Debug = log.New(debugW, "DEBUG: ", log.Lshortfile)
-	Info = log.New(infoW, "INFO: ", log.Lshortfile)
-	Warning = log.New(warnW, "WARNING: ", log.Lshortfile)
-	Error = log.New(errW, "ERROR: ", log.Lshortfile)
-	Event = log.New(eventW, "", 0)
+func initLogger(logger **log.Logger, oldLogCloser *io.Closer, newLogWriter io.WriteCloser, logPrefix string, logFlags int) {
+	if *logger != nil {
+		(*logger).SetOutput(newLogWriter)
+	} else {
+		*logger = log.New(newLogWriter, logPrefix, logFlags)
+	}
+	if *oldLogCloser != nil {
+		(*oldLogCloser).Close()
+	}
+	*oldLogCloser = newLogWriter
+}
+
+// Init initailizes the logs with the given io.WriteClosers. If `Init` was previously called, existing loggers are Closed. If you have loggers which are not Closers or which must not be Closed, wrap them with `log.NopCloser`.
+func Init(eventW, errW, warnW, infoW, debugW io.WriteCloser) {
+	initLogger(&Debug, &debugCloser, debugW, "DEBUG: ", log.Lshortfile)
+	initLogger(&Info, &infoCloser, infoW, "INFO: ", log.Lshortfile)
+	initLogger(&Warning, &warnCloser, warnW, "WARNING: ", log.Lshortfile)
+	initLogger(&Error, &errCloser, errW, "ERROR: ", log.Lshortfile)
+	initLogger(&Event, &eventCloser, eventW, "", 0)
 }
 
 const timeFormat = time.RFC3339Nano
@@ -110,3 +128,13 @@ func Writef(w io.Writer, b []byte, contextFormat string, v ...interface{}) {
 		Errorf(": %v", err)
 	}
 }
+
+type nopCloser struct {
+	io.Writer
+}
+
+func (nopCloser) Close() error { return nil }
+
+func NopCloser(w io.Writer) io.WriteCloser {
+	return nopCloser{w}
+}

http://git-wip-us.apache.org/repos/asf/incubator-trafficcontrol/blob/240043f5/traffic_monitor_golang/traffic_monitor/traffic_monitor.go
----------------------------------------------------------------------
diff --git a/traffic_monitor_golang/traffic_monitor/traffic_monitor.go b/traffic_monitor_golang/traffic_monitor/traffic_monitor.go
index 032b339..fe7dc38 100644
--- a/traffic_monitor_golang/traffic_monitor/traffic_monitor.go
+++ b/traffic_monitor_golang/traffic_monitor/traffic_monitor.go
@@ -40,19 +40,19 @@ var GitRevision = "No Git Revision Specified. Please build with '-X main.GitRevi
 // BuildTimestamp is the time the app was built. The app SHOULD always be built with this set via the `-X` flag.
 var BuildTimestamp = "No Build Timestamp Specified. Please build with '-X main.BuildTimestamp=`date +'%Y-%M-%dT%H:%M:%S'`"
 
-func getLogWriter(location string) (io.Writer, error) {
+func getLogWriter(location string) (io.WriteCloser, error) {
 	switch location {
 	case config.LogLocationStdout:
-		return os.Stdout, nil
+		return log.NopCloser(os.Stdout), nil
 	case config.LogLocationStderr:
-		return os.Stderr, nil
+		return log.NopCloser(os.Stderr), nil
 	case config.LogLocationNull:
-		return ioutil.Discard, nil
+		return log.NopCloser(ioutil.Discard), nil
 	default:
 		return os.OpenFile(location, os.O_WRONLY|os.O_CREATE|os.O_APPEND, 0644)
 	}
 }
-func getLogWriters(eventLoc, errLoc, warnLoc, infoLoc, debugLoc string) (io.Writer, io.Writer, io.Writer, io.Writer, io.Writer, error) {
+func getLogWriters(eventLoc, errLoc, warnLoc, infoLoc, debugLoc string) (io.WriteCloser, io.WriteCloser, io.WriteCloser, io.WriteCloser, io.WriteCloser, error) {
 	eventW, err := getLogWriter(eventLoc)
 	if err != nil {
 		return nil, nil, nil, nil, nil, fmt.Errorf("getting log event writer %v: %v", eventLoc, err)