WIP: Journal - Heketi should keep track of transactions

Journal support is a simple concept where heketi keeps track
of transaction and has capability to revert back to a consistent
state or continue from the point where transaction was stopped.

In case of Volume create transaction,

Brick entries are added to the devices and under volume entries
after creating bricks(or lv's on devices). Before all the bricks
created for the volume, heketi process is forcefully terminated.
DB parsing is failed as there are no complete volume entries.

Someone has to cleanup or resume the transaction. Thats journal
responsibility now.

Pair-Programmed-With: Raghavendra Talur rtalur@redhat.com

Signed-off-by: Mohamed Ashiq Liyazudeen mliyazud@redhat.com
Signed-off-by: Raghavendra Talur rtalur@redhat.com

apps/glusterfs/app.go

@@ -38,6 +38,7 @@ const (
 
 var (
 	logger     = utils.NewLogger("[heketi]", utils.LEVEL_INFO)
+	journal    = utils.NewJournal("/tmp/journal")
 	dbfilename = "heketi.db"
 )
 
@@ -168,6 +169,13 @@ func NewApp(configIo io.Reader) *App {
 	}
 	logger.Info("Loaded %v allocator", app.conf.Allocator)
 
+	// Journal File is checked
+	check, err := journal.JournalCheck()
+	if check == false {
+		logger.Critical("Journal not clean", err)
+		return nil
+	}
+
 	// Show application has loaded
 	logger.Info("GlusterFS Application Loaded")
 

apps/glusterfs/app_volume.go

@@ -34,6 +34,12 @@ func (a *App) VolumeCreate(w http.ResponseWriter, r *http.Request) {
 		http.Error(w, "request unable to be parsed", 422)
 		return
 	}
+	content := fmt.Sprintf("START volume create size %v Cluster %v Durability %v", msg.Size, msg.Clusters, msg.Durability)
+	err = journal.WriteJ(content)
+	if err != nil {
+		http.Error(w, "Journal volume create writer failed", 422)
+		return
+	}
 
 	// Check group id
 	switch {
@@ -162,6 +168,8 @@ func (a *App) VolumeCreate(w http.ResponseWriter, r *http.Request) {
 		return "/volumes/" + vol.Info.Id, nil
 	})
 
+	content = fmt.Sprintf("END volume create size %v Cluster %v Durability %v", msg.Size, msg.Clusters, msg.Durability)
+	journal.WriteJ(content)
 }
 
 func (a *App) VolumeList(w http.ResponseWriter, r *http.Request) {

pkg/utils/journal.go

@@ -0,0 +1,105 @@
+//
+// Copyright (c) 2015 The heketi Authors
+//
+// This file is licensed to you under your choice of the GNU Lesser
+// General Public License, version 3 or any later version (LGPLv3 or
+// later), or the GNU General Public License, version 2 (GPLv2), in all
+// cases as published by the Free Software Foundation.
+//
+
+package utils
+
+import (
+	"bufio"
+	"os"
+	"strings"
+
+	"github.com/lpabon/godbc"
+)
+
+type Journal struct {
+	Path  string
+	Clean bool
+}
+
+// Create a new journal
+func NewJournal(path string) *Journal {
+
+	godbc.Check(path != "", path)
+
+	j := &Journal{}
+
+	// open output file
+	f, err := os.OpenFile(path, os.O_CREATE|os.O_RDWR|os.O_APPEND, 0666)
+	if err != nil {
+		panic(err)
+	}
+	j.Path = path
+
+	// close fo on exit and check for its returned error
+	defer func() {
+		if err := f.Close(); err != nil {
+			panic(err)
+		}
+	}()
+
+	return j
+}
+
+func readLines(path string) ([]string, error) {
+	file, err := os.Open(path)
+	if err != nil {
+		return nil, err
+	}
+	defer file.Close()
+
+	var lines []string
+	scanner := bufio.NewScanner(file)
+	for scanner.Scan() {
+		lines = append(lines, scanner.Text())
+	}
+	return lines, scanner.Err()
+}
+
+func (j *Journal) JournalCheck() (bool, error) {
+	check := j.Clean
+	path := j.Path
+	scount := 0
+	ecount := 0
+
+	journal, err := readLines(path)
+	if err != nil {
+		check = false
+	}
+
+	for _, lines := range journal {
+		if strings.Contains(lines, "START") {
+			scount++
+		}
+		if strings.Contains(lines, "END") {
+			ecount++
+		}
+	}
+
+	if scount == ecount {
+		check = true
+	} else {
+		check = false
+	}
+	j.Clean = check
+	return check, nil
+}
+
+func (j *Journal) WriteJ(text string) error {
+	path := j.Path
+	f, err := os.OpenFile(path, os.O_APPEND|os.O_RDWR, 0666)
+	if err != nil {
+		panic(err)
+	}
+	defer f.Close()
+
+	_, err = f.WriteString(text)
+	if err != nil {
+	}
+	return err
+}