mdb/database.go

package mdb

import (
	"net"
	"os"
	"path/filepath"
	"sync"

	"git.crumpington.com/private/mdb/kvstore"
	"golang.org/x/sys/unix"
)

type Database struct {
	root string
	lock *os.File
	kv   *kvstore.KV

	collections map[string]dbCollection
}

func NewPrimary(root string) *Database {
	return newDB(root, true)
}

func NewSecondary(root string) *Database {
	return newDB(root, false)
}

func newDB(root string, primary bool) *Database {
	must(os.MkdirAll(root, 0700))

	lockPath := filepath.Join(root, "lock")

	// Acquire the lock.
	lock, err := os.OpenFile(lockPath, os.O_RDWR|os.O_CREATE, 0600)
	must(err)
	must(unix.Flock(int(lock.Fd()), unix.LOCK_EX))

	db := &Database{
		root:        root,
		collections: map[string]dbCollection{},
		lock:        lock,
	}
	if primary {
		db.kv = kvstore.NewPrimary(root)
	} else {
		db.kv = kvstore.NewSecondary(root, db.onStore, db.onDelete)
	}
	return db
}

func (db *Database) Start() {
	wg := sync.WaitGroup{}
	for _, c := range db.collections {
		wg.Add(1)
		go func(c dbCollection) {
			defer wg.Done()
			c.loadData()
		}(c)
	}
	wg.Wait()
}

func (db *Database) MaxSeqNum() uint64 {
	return db.kv.MaxSeqNum()
}

func (db *Database) Close() {
	if db.kv != nil {
		db.kv.Close()
		db.kv = nil
	}
	if db.lock != nil {
		db.lock.Close()
		db.lock = nil
	}
}

// ----------------------------------------------------------------------------

func (db *Database) onStore(collection string, id uint64, data []byte) {
	c, ok := db.collections[collection]
	if ok {
		c.onStore(id, data)
	}
}

func (db *Database) onDelete(collection string, id uint64) {
	c, ok := db.collections[collection]
	if ok {
		c.onDelete(id)
	}
}

// ----------------------------------------------------------------------------

func (db *Database) SyncSend(conn net.Conn) {
	db.kv.SyncSend(conn)
}

func (db *Database) SyncRecv(conn net.Conn) {
	db.kv.SyncRecv(conn)
}