adding fail channel to bubble errors

scribble.go

@@ -0,0 +1,215 @@
+package scribble
+
+import (
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+	"os"
+	"strings"
+
+	"github.com/nanobox-core/hatchet"
+)
+
+//
+const Version = "0.0.1"
+
+//
+type (
+
+	// Driver
+	Driver struct {
+		channels map[string]chan int
+		dir      string
+		log      *hatchet.Logger
+	}
+
+	// Transaction represents
+	Transaction struct {
+		Action     string
+		Collection string
+		Resource   string
+		Container  interface{}
+	}
+)
+
+// New
+func New(dir string, logger hatchet.Logger) (*Driver, error) {
+	fmt.Printf("Creating database directory at '%v'...\n", dir)
+
+	scribble := &Driver{}
+	scribble.dir = dir
+	scribble.channels = make(map[string]chan int)
+
+	//
+	if err := mkDir(scribble.dir); err != nil {
+		return nil, err
+	}
+
+	//
+	return scribble, nil
+}
+
+// Transact
+func (d *Driver) Transact(trans Transaction) error {
+
+	//
+	done := d.getOrCreateChan(trans.Collection)
+	fail := make(chan error)
+
+	//
+	switch trans.Action {
+	case "write":
+		go d.write(trans, done, fail)
+	case "read":
+		go d.read(trans, done, fail)
+	case "readall":
+		go d.readAll(trans, done, fail)
+	case "delete":
+		go d.delete(trans, done, fail)
+	default:
+		fmt.Println("Unsupported action ", trans.Action)
+	}
+
+	// wait until we're done, or error
+	select {
+	case <-done:
+		return nil
+	case err := <-fail:
+		return err
+	}
+}
+
+// private
+
+// write
+func (d *Driver) write(trans Transaction, done chan<- int, fail chan<- error) {
+
+	//
+	dir := d.dir + "/" + trans.Collection
+
+	//
+	if err := mkDir(dir); err != nil {
+		fail <- err
+	}
+
+	//
+	file, err := os.Create(dir + "/" + trans.Resource)
+	if err != nil {
+		fail <- err
+	}
+
+	defer file.Close()
+
+	//
+	b, err := json.MarshalIndent(trans.Container, "", "\t")
+	if err != nil {
+		fail <- err
+	}
+
+	_, err = file.WriteString(string(b))
+	if err != nil {
+		fail <- err
+	}
+
+	// release...
+	done <- 0
+}
+
+// read
+func (d *Driver) read(trans Transaction, done chan<- int, fail chan<- error) interface{} {
+
+	dir := d.dir + "/" + trans.Collection
+
+	b, err := ioutil.ReadFile(dir + "/" + trans.Resource)
+	if err != nil {
+		fmt.Printf("Unable to read file %v/%v: %v", trans.Collection, trans.Resource, err)
+		os.Exit(1)
+	}
+
+	if err := json.Unmarshal(b, trans.Container); err != nil {
+		fail <- err
+	}
+
+	// release...
+	done <- 0
+
+	return trans.Container
+}
+
+// readAll
+func (d *Driver) readAll(trans Transaction, done chan<- int, fail chan<- error) {
+
+	dir := d.dir + "/" + trans.Collection
+
+	//
+	files, err := ioutil.ReadDir(dir)
+
+	// an error here just means an empty collection so do nothing
+	if err != nil {
+	}
+
+	var f []string
+
+	for _, file := range files {
+		b, err := ioutil.ReadFile(dir + "/" + file.Name())
+		if err != nil {
+			fail <- err
+		}
+
+		f = append(f, string(b))
+	}
+
+	//
+	if err := json.Unmarshal([]byte("["+strings.Join(f, ",")+"]"), trans.Container); err != nil {
+		fail <- err
+	}
+
+	// release...
+	done <- 0
+}
+
+// delete
+func (d *Driver) delete(trans Transaction, done chan<- int, fail chan<- error) {
+
+	dir := d.dir + "/" + trans.Collection
+
+	err := os.Remove(dir + "/" + trans.Resource)
+	if err != nil {
+		fail <- err
+	}
+
+	// release...
+	done <- 0
+}
+
+// helpers
+
+// getChan
+func (d *Driver) getOrCreateChan(channel string) chan int {
+
+	c, ok := d.channels[channel]
+
+	// if the chan doesn't exist make it
+	if !ok {
+		d.channels[channel] = make(chan int)
+		return d.channels[channel]
+	}
+
+	return c
+}
+
+// mkDir
+func mkDir(d string) error {
+
+	//
+	dir, _ := os.Stat(d)
+
+	if dir == nil {
+		err := os.MkdirAll(d, 0755)
+		if err != nil {
+			return err
+		}
+	}
+
+	return nil
+}