Restore Graceful Restarting & Socket Activation (#7274)

* Prevent deadlock in indexer initialisation during graceful restart

* Move from gracehttp to our own service to add graceful ssh

* Add timeout for start of indexers and make hammer time configurable

* Fix issue with re-initialization in indexer during tests

* move the code to detect use of closed to graceful

* Handle logs gracefully - add a pid suffix just before restart

* Move to using a cond and a holder for indexers

* use time.Since

* Add some comments and attribution

* update modules.txt

* Use zero to disable timeout

* Move RestartProcess to its own file

* Add cleanup routine

modules/setting/log.go

@@ -6,6 +6,7 @@ package setting
 
 import (
 	"encoding/json"
+	"fmt"
 	golog "log"
 	"os"
 	"path"
@@ -17,6 +18,8 @@ import (
 	ini "gopkg.in/ini.v1"
 )
 
+var filenameSuffix = ""
+
 type defaultLogOptions struct {
 	levelName      string // LogLevel
 	flags          string
@@ -112,7 +115,7 @@ func generateLogConfig(sec *ini.Section, name string, defaults defaultLogOptions
 			panic(err.Error())
 		}
 
-		logConfig["filename"] = logPath
+		logConfig["filename"] = logPath + filenameSuffix
 		logConfig["rotate"] = sec.Key("LOG_ROTATE").MustBool(true)
 		logConfig["maxsize"] = 1 << uint(sec.Key("MAX_SIZE_SHIFT").MustInt(28))
 		logConfig["daily"] = sec.Key("DAILY_ROTATE").MustBool(true)
@@ -277,6 +280,12 @@ func newLogService() {
 	golog.SetOutput(log.NewLoggerAsWriter("INFO", log.GetLogger(log.DEFAULT)))
 }
 
+// RestartLogsWithPIDSuffix restarts the logs with a PID suffix on files
+func RestartLogsWithPIDSuffix() {
+	filenameSuffix = fmt.Sprintf(".%d", os.Getpid())
+	NewLogServices(false)
+}
+
 // NewLogServices creates all the log services
 func NewLogServices(disableConsole bool) {
 	newLogService()