introduce filesystem database (#483)

README.md

@@ -452,6 +452,19 @@ gesundheit -conf /etc/gesundheit/gesundheit.toml
     </tr>
   </thead>
   <tbody>
+    <tr>
+      <td rowspan="2"><strong>filesystem</strong></td>
+      <td rowspan="2">Simple filesystem baked database suitable for most setups.</td>
+      <td>Directory</td>
+      <td>Database directory, e.g. <code>"/var/lib/gesundheit"</td>
+    </tr>
+    <tr>
+      <td>VacuumInterval</td>
+      <td>
+        Interval in which expired entries are deleted from disk,
+        e.g. <code>"24h"</code>
+      </td>
+    </tr>
     <tr>
       <td><strong>memory</strong></td>
       <td>

db/filesystem/database.go

@@ -0,0 +1,163 @@
+package filesystem
+
+import (
+	"context"
+	"encoding/json"
+	"io"
+	"log"
+	"os"
+	"path/filepath"
+	"sync"
+	"time"
+
+	"github.com/ushis/gesundheit/db"
+	"github.com/ushis/gesundheit/db/memory"
+	"github.com/ushis/gesundheit/result"
+)
+
+func init() {
+	db.Register("filesystem", New)
+}
+
+const walFilename = "gesundheit.wal"
+const tmpWalFilename = "_gesundheit.wal"
+
+type Database struct {
+	*sync.Mutex
+	db               db.Database
+	log              *os.File
+	directory        string
+	vacuumInterval   time.Duration
+	cancelAutoVacuum context.CancelFunc
+}
+
+type Config struct {
+	Directory      string
+	VacuumInterval string
+}
+
+func New(configure func(interface{}) error) (db.Database, error) {
+	conf := Config{Directory: ".", VacuumInterval: "24 hours"}
+
+	if err := configure(&conf); err != nil {
+		return nil, err
+	}
+	vacuumInterval, err := time.ParseDuration(conf.VacuumInterval)
+
+	if err != nil {
+		return nil, err
+	}
+	memoryDB, err := memory.New(nil)
+
+	if err != nil {
+		return nil, err
+	}
+	log, err := os.OpenFile(
+		filepath.Join(conf.Directory, walFilename),
+		os.O_APPEND|os.O_CREATE|os.O_RDWR,
+		0755,
+	)
+	if err != nil {
+		return nil, err
+	}
+	if err := readEvents(log, memoryDB.InsertEvent); err != nil {
+		return nil, err
+	}
+	ctx, cancel := context.WithCancel(context.Background())
+	db := &Database{&sync.Mutex{}, memoryDB, log, conf.Directory, vacuumInterval, cancel}
+	go db.autoVacuum(ctx)
+	return db, nil
+}
+
+func (db *Database) Close() error {
+	db.Lock()
+	defer db.Unlock()
+
+	db.cancelAutoVacuum()
+	return db.log.Close()
+}
+
+func (db *Database) InsertEvent(e result.Event) (bool, error) {
+	db.Lock()
+	defer db.Unlock()
+
+	if err := json.NewEncoder(db.log).Encode(e); err != nil {
+		return false, err
+	}
+	return db.db.InsertEvent(e)
+}
+
+func (db *Database) GetEvents() ([]result.Event, error) {
+	return db.db.GetEvents()
+}
+
+func (db *Database) GetEventsByNode(name string) ([]result.Event, error) {
+	return db.db.GetEventsByNode(name)
+}
+
+func (db *Database) autoVacuum(ctx context.Context) {
+	for {
+		select {
+		case <-time.After(db.vacuumInterval):
+		case <-ctx.Done():
+			return
+		}
+		log.Println("db: vacuum: start")
+
+		if err := db.vacuum(); err != nil {
+			log.Println("db: vacuum: failed:", err)
+		} else {
+			log.Println("db: vacuum: done")
+		}
+	}
+}
+
+func (db *Database) vacuum() error {
+	db.Lock()
+	defer db.Unlock()
+
+	newLog, err := os.OpenFile(
+		filepath.Join(db.directory, tmpWalFilename),
+		os.O_CREATE|os.O_TRUNC|os.O_WRONLY,
+		0755,
+	)
+	if err != nil {
+		return err
+	}
+	events, err := db.db.GetEvents()
+
+	if err != nil {
+		return err
+	}
+	w := json.NewEncoder(newLog)
+
+	for _, event := range events {
+		if err := w.Encode(event); err != nil {
+			return err
+		}
+	}
+	db.log.Close()
+	db.log = newLog
+
+	return os.Rename(
+		filepath.Join(db.directory, tmpWalFilename),
+		filepath.Join(db.directory, walFilename),
+	)
+}
+
+func readEvents(r io.Reader, insertEvent func(result.Event) (bool, error)) error {
+	decoder := json.NewDecoder(r)
+
+	for {
+		event := result.Event{}
+
+		if err := decoder.Decode(&event); err == io.EOF {
+			return nil
+		} else if err != nil {
+			return err
+		}
+		if _, err := insertEvent(event); err != nil {
+			return err
+		}
+	}
+}

main.go

@@ -5,7 +5,6 @@ import (
 	"flag"
 	"fmt"
 	"io"
-	"io/ioutil"
 	"log"
 	"math/rand"
 	"os"
@@ -27,6 +26,7 @@ import (
 	_ "github.com/ushis/gesundheit/check/node-alive"
 	_ "github.com/ushis/gesundheit/check/tls-cert"
 	"github.com/ushis/gesundheit/crypto"
+	_ "github.com/ushis/gesundheit/db/filesystem"
 	_ "github.com/ushis/gesundheit/db/memory"
 	_ "github.com/ushis/gesundheit/db/redis"
 	_ "github.com/ushis/gesundheit/filter/office-hours"
@@ -169,7 +169,7 @@ func cmdPubkey(args []string) {
 		flags.Usage()
 		os.Exit(2)
 	}
-	buf, err := ioutil.ReadAll(os.Stdin)
+	buf, err := io.ReadAll(os.Stdin)
 
 	if err != nil {
 		log.Fatalln("failed to read:", err)