Add lock around dummy DA data (#21)

* Add lock around dummy DA data

* Add concurrent read/write test

* Increase counter in concurrent test

test/dummy.go

@@ -7,6 +7,7 @@ import (
 	"crypto/sha256"
 	"encoding/binary"
 	"errors"
+	"sync"
 
 	"github.com/rollkit/go-da"
 )
@@ -16,10 +17,11 @@ import (
 // Data is stored in a map, where key is a serialized sequence number. This key is returned as ID.
 // Commitments are simply hashes, and proofs are ED25519 signatures.
 type DummyDA struct {
+	mu      *sync.Mutex // protects data and height
 	data    map[uint64][]kvp
+	height  uint64
 	privKey ed25519.PrivateKey
 	pubKey  ed25519.PublicKey
-	height  uint64
 }
 
 type kvp struct {
@@ -29,6 +31,7 @@ type kvp struct {
 // NewDummyDA create new instance of DummyDA
 func NewDummyDA() *DummyDA {
 	da := &DummyDA{
+		mu:   new(sync.Mutex),
 		data: make(map[uint64][]kvp),
 	}
 	da.pubKey, da.privKey, _ = ed25519.GenerateKey(rand.Reader)
@@ -39,6 +42,8 @@ var _ da.DA = &DummyDA{}
 
 // Get returns Blobs for given IDs.
 func (d *DummyDA) Get(ids []da.ID) ([]da.Blob, error) {
+	d.mu.Lock()
+	defer d.mu.Unlock()
 	blobs := make([]da.Blob, len(ids))
 	for i, id := range ids {
 		if len(id) < 8 {
@@ -61,6 +66,8 @@ func (d *DummyDA) Get(ids []da.ID) ([]da.Blob, error) {
 
 // GetIDs returns IDs of Blobs at given DA height.
 func (d *DummyDA) GetIDs(height uint64) ([]da.ID, error) {
+	d.mu.Lock()
+	defer d.mu.Unlock()
 	kvps := d.data[height]
 	ids := make([]da.ID, len(kvps))
 	for i, kv := range kvps {
@@ -80,6 +87,8 @@ func (d *DummyDA) Commit(blobs []da.Blob) ([]da.Commitment, error) {
 
 // Submit stores blobs in DA layer.
 func (d *DummyDA) Submit(blobs []da.Blob) ([]da.ID, []da.Proof, error) {
+	d.mu.Lock()
+	defer d.mu.Unlock()
 	ids := make([]da.ID, len(blobs))
 	proofs := make([]da.Proof, len(blobs))
 	d.height += 1

test/test_suite.go

@@ -2,6 +2,7 @@ package test
 
 import (
 	"bytes"
+	"sync"
 	"testing"
 	"time"
 
@@ -21,6 +22,9 @@ func RunDATestSuite(t *testing.T, d da.DA) {
 	t.Run("Check Errors", func(t *testing.T) {
 		CheckErrors(t, d)
 	})
+	t.Run("Concurrent read/write test", func(t *testing.T) {
+		ConcurrentReadWriteTest(t, d)
+	})
 }
 
 // TODO(tzdybal): how to get rid of those aliases?
@@ -141,3 +145,27 @@ func GetIDsTest(t *testing.T, da da.DA) {
 
 	assert.True(t, found)
 }
+
+// ConcurrentReadWriteTest tests the use of mutex lock in DummyDA by calling separate methods that use `d.data` and making sure there's no race conditions
+func ConcurrentReadWriteTest(t *testing.T, da da.DA) {
+	var wg sync.WaitGroup
+	wg.Add(2)
+
+	go func() {
+		defer wg.Done()
+		for i := uint64(0); i < 100; i++ {
+			_, err := da.GetIDs(i)
+			assert.NoError(t, err)
+		}
+	}()
+
+	go func() {
+		defer wg.Done()
+		for i := uint64(0); i < 100; i++ {
+			_, _, err := da.Submit([][]byte{[]byte("test")})
+			assert.NoError(t, err)
+		}
+	}()
+
+	wg.Wait()
+}