commit of code

cmd/kvrepl/main.go

@@ -0,0 +1,26 @@
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+
+	"s.mcquay.me/dm/kvrepl"
+)
+
+func main() {
+	d := &kvrepl.DB{PKV: true}
+	d.KV1 = make(map[string]string)
+	d.KV2 = make(map[string]string)
+	scanner := bufio.NewScanner(os.Stdin)
+	for scanner.Scan() {
+		v, err := kvrepl.Parse(scanner.Text(), d)
+		if err != nil {
+			fmt.Fprintln(os.Stderr, err)
+		} else {
+			if v != "" {
+				fmt.Println(v)
+			}
+		}
+	}
+}

db.go

@@ -0,0 +1,48 @@
+package kvrepl
+
+import "fmt"
+
+type DB struct {
+	KV1  map[string]string
+	KV2  map[string]string
+	PKV  bool
+	nest int
+}
+
+func read(args []string, kv map[string]string) (string, error) {
+	if len(args) != 1 {
+		return "", fmt.Errorf("incorrect usage: READ <key>")
+	}
+	i, ok := kv[args[0]]
+	if !ok {
+		return "", fmt.Errorf("key does not exist")
+	}
+	return i, nil
+}
+
+func write(args []string, kv map[string]string) error {
+	if len(args) != 2 {
+		return fmt.Errorf("incorrect usage: WRITE <key> <value>")
+	}
+	kv[args[0]] = args[1]
+	return nil
+}
+
+func del(args []string, kv map[string]string) error {
+	if len(args) != 1 {
+		return fmt.Errorf("incorrect usage: DELETE <key>")
+	}
+	_, ok := kv[args[0]]
+	if !ok {
+		return fmt.Errorf("key does not exist")
+	}
+	delete(kv, args[0])
+	return nil
+}
+
+func whichDB(d *DB) map[string]string {
+	if d.PKV {
+		return d.KV1
+	}
+	return d.KV2
+}

db_test.go

@@ -0,0 +1,102 @@
+package kvrepl
+
+import "testing"
+
+func TestRead(t *testing.T) {
+	var tests = []struct {
+		args     []string
+		kv       map[string]string
+		expected bool
+	}{
+		{[]string{}, nil, false},
+		{[]string{"a", "b"}, nil, false},
+		{[]string{"a"}, map[string]string{}, false},
+		{[]string{"a"}, map[string]string{"a": "b"}, true},
+	}
+
+	for _, rt := range tests {
+		_, actual := read(rt.args, rt.kv)
+		if (actual == nil) != rt.expected {
+			t.Errorf(
+				"failed read:\n\texpected: %v\n\t  actual: %v",
+				rt.expected,
+				(actual == nil),
+			)
+		}
+	}
+}
+
+func TestWrite(t *testing.T) {
+	var tests = []struct {
+		args     []string
+		kv       map[string]string
+		expected bool
+	}{
+		{[]string{}, nil, false},
+		{[]string{"a"}, nil, false},
+		{[]string{"a", "b"}, map[string]string{}, true},
+	}
+
+	for _, rt := range tests {
+		actual := write(rt.args, rt.kv)
+		if (actual == nil) != rt.expected {
+			t.Errorf(
+				"failed write:\n\texpected: %v\n\t  actual: %v",
+				rt.expected,
+				(actual == nil),
+			)
+		}
+	}
+}
+
+func TestDel(t *testing.T) {
+	var tests = []struct {
+		args     []string
+		kv       map[string]string
+		expected bool
+	}{
+		{[]string{}, nil, false},
+		{[]string{"a", "b"}, nil, false},
+		{[]string{"a"}, map[string]string{}, false},
+		{[]string{"a"}, map[string]string{"a": "b"}, true},
+	}
+
+	for _, rt := range tests {
+		actual := del(rt.args, rt.kv)
+		if (actual == nil) != rt.expected {
+			t.Errorf(
+				"failed del:\n\texpected: %v\n\t  actual: %v",
+				rt.expected,
+				(actual == nil),
+			)
+		}
+	}
+}
+
+func TestSeries(t *testing.T) {
+	kv := make(map[string]string)
+	err := write([]string{"a", "b"}, kv)
+	if err != nil {
+		t.Errorf(
+			"failed series:\n\tfailed to write",
+		)
+	}
+	v, err := read([]string{"a"}, kv)
+	if v != "b" {
+		t.Errorf(
+			"failed series:\n\texpected: %v\n\t  actual: %v",
+			"b",
+			v,
+		)
+	}
+	err = del([]string{"a"}, kv)
+	v, err = read([]string{"a"}, kv)
+	if v != "" {
+		t.Errorf(
+			"failed series:\n\texpected: %v\n\t  actual: %v",
+			"",
+			v,
+		)
+	}
+
+}

parse.go

@@ -0,0 +1,59 @@
+package kvrepl
+
+import (
+	"fmt"
+	"os"
+	"strings"
+)
+
+func Parse(s string, d *DB) (string, error) {
+	args := strings.Split(s, " ")
+
+	switch strings.ToLower(args[0]) {
+	case "read":
+		return read(args[1:], whichDB(d))
+	case "write":
+		return "", write(args[1:], whichDB(d))
+	case "delete":
+		return "", del(args[1:], whichDB(d))
+	case "start":
+		if len(args) != 1 {
+			return "", fmt.Errorf("incorrect usage: START")
+		}
+		d.nest++
+		d.PKV = false
+
+		// copy contents of KV1 to KV2
+		d.KV2 = make(map[string]string)
+		for k, v := range d.KV1 {
+			d.KV2[k] = v
+		}
+	case "commit":
+		if len(args) != 1 {
+			return "", fmt.Errorf("incorrect usage: COMMIT")
+		}
+		if d.PKV {
+			return "", fmt.Errorf("not in a transaction")
+		}
+		if d.nest == 0 {
+			d.PKV = true
+			// copy contents of KV2 to KV1
+			d.KV1 = make(map[string]string)
+			for k, v := range d.KV2 {
+				d.KV1[k] = v
+			}
+		}
+
+	case "abort":
+		if len(args) != 1 {
+			return "", fmt.Errorf("incorrect usage: ABORT")
+		}
+		d.PKV = true
+	case "quit":
+		fmt.Println("goodbye")
+		os.Exit(0)
+	default:
+		fmt.Println("not known command")
+	}
+	return "", nil
+}

parse_test.go

@@ -0,0 +1,147 @@
+package kvrepl
+
+import "testing"
+
+func TestParse(t *testing.T) {
+	var tests = []struct {
+		cmds     []string
+		db       *DB
+		expected string
+	}{
+		{
+			cmds: []string{
+				"write a b",
+				"start",
+				"write a c",
+				"abort",
+				"read a",
+			},
+			db: &DB{
+				KV1: map[string]string{},
+				KV2: map[string]string{},
+				PKV: true,
+			},
+			expected: "b",
+		},
+		{
+			cmds: []string{
+				"write a b",
+				"start",
+				"write a hello-again",
+				"start",
+				"delete a",
+				"commit",
+				"write a once-more",
+				"abort",
+				"read a",
+			},
+			db: &DB{
+				KV1: map[string]string{},
+				KV2: map[string]string{},
+				PKV: true,
+			},
+			expected: "b",
+		},
+		{
+			cmds: []string{
+				"write a b",
+				"start",
+				"write a hello-again",
+				"start",
+				"delete a",
+				"commit",
+				"write a once-more",
+				"start",
+				"write a foo",
+				"abort",
+				"read a",
+			},
+			db: &DB{
+				KV1: map[string]string{},
+				KV2: map[string]string{},
+				PKV: true,
+			},
+			expected: "b",
+		},
+		{
+			cmds: []string{
+				"write a b",
+				"start",
+				"write a c",
+				"commit",
+				"read a",
+			},
+			db: &DB{
+				KV1: map[string]string{},
+				KV2: map[string]string{},
+				PKV: true,
+			},
+			expected: "c",
+		},
+		{
+			cmds: []string{
+				"write a b",
+				"start",
+				"write a c",
+				"start",
+				"delete a",
+				"write a d",
+				"commit",
+				"read a",
+			},
+			db: &DB{
+				KV1: map[string]string{},
+				KV2: map[string]string{},
+				PKV: true,
+			},
+			expected: "d",
+		},
+		{
+			cmds: []string{
+				"write a b",
+				"start",
+				"write a c",
+				"start",
+				"delete a",
+				"write a d",
+				"abort",
+				"read a",
+			},
+			db: &DB{
+				KV1: map[string]string{},
+				KV2: map[string]string{},
+				PKV: true,
+			},
+			expected: "b",
+		},
+		{
+			cmds: []string{
+				"write a b",
+				"start",
+				"delete a",
+				"commit",
+				"read a",
+			},
+			db: &DB{
+				KV1: map[string]string{},
+				KV2: map[string]string{},
+				PKV: true,
+			},
+			expected: "",
+		},
+	}
+
+	for _, rt := range tests {
+		actual := ""
+		for _, c := range rt.cmds {
+			actual, _ = Parse(c, rt.db)
+		}
+		if actual != rt.expected {
+			t.Errorf(
+				"failed parse:\n\texpected: %v\n\t  actual: %v",
+				rt.expected,
+				actual,
+			)
+		}
+	}
+}