Tracking, conflict resolution, and dedupe

gun/gun.go

@@ -39,6 +39,7 @@ const (
 )
 
 const DefaultPeerSleepOnError = 30 * time.Second
+const DefaultOldestAllowedStorageValue = 7 * (60 * time.Minute)
 
 func New(ctx context.Context, config Config) (*Gun, error) {
 	g := &Gun{
@@ -75,7 +76,7 @@ func New(ctx context.Context, config Config) (*Gun, error) {
 	}
 	// Set defaults
 	if g.storage == nil {
-		g.storage = &StorageInMem{}
+		g.storage = NewStorageInMem(DefaultOldestAllowedStorageValue)
 	}
 	if g.soulGen == nil {
 		g.soulGen = DefaultSoulGen
@@ -103,6 +104,9 @@ func (g *Gun) Close() error {
 			errs = append(errs, err)
 		}
 	}
+	if err := g.storage.Close(); err != nil {
+		errs = append(errs, err)
+	}
 	if len(errs) == 0 {
 		return nil
 	} else if len(errs) == 1 {
@@ -165,6 +169,17 @@ func (g *Gun) startReceiving() {
 }
 
 func (g *Gun) onPeerMessage(ctx context.Context, msg *MessageReceived) {
+	// If we're tracking everything, persist all puts here.
+	if g.tracking == TrackingEverything {
+		for parentSoul, node := range msg.Put {
+			for field, value := range node.Values {
+				if state, ok := node.Metadata.State[field]; ok {
+					// TODO: warn on error or something
+					g.storage.Put(ctx, parentSoul, field, value, state, false)
+				}
+			}
+		}
+	}
 	// If there is a listener for this message, use it
 	if msg.Ack != "" {
 		g.messageIDListenersLock.RLock()

gun/node.go

@@ -122,9 +122,3 @@ func (ValueRelation) nodeValue() {}
 func (n ValueRelation) MarshalJSON() ([]byte, error) {
 	return json.Marshal(map[string]string{"#": string(n)})
 }
-
-// type ValueWithState struct {
-// 	Value Value
-// 	// This is 0 for top-level values
-// 	State int64
-// }

gun/scoped_fetch.go

@@ -89,8 +89,10 @@ func (s *Scoped) fetchRemote(ctx context.Context, ch chan *FetchResult) {
 	s.fetchResultListenersLock.Unlock()
 	// Listen for responses to this get
 	s.gun.registerMessageIDListener(req.ID, msgCh)
-	// TODO: only for children: s.gun.RegisterValueIDListener(s.id, msgCh)
+	// TODO: Also listen for any changes to the value or just for specific requests?
 	// Handle received messages turning them to value fetches
+	var lastSeenValue Value
+	var lastSeenState State
 	go func() {
 		for {
 			select {
@@ -106,12 +108,28 @@ func (s *Scoped) fetchRemote(ctx context.Context, ch chan *FetchResult) {
 				// We asked for a single field, should only get that field or it doesn't exist
 				if msg.Err != "" {
 					r.Err = fmt.Errorf("Remote error: %v", msg.Err)
-				} else if n := msg.Put[parentSoul]; n != nil && n.Values[s.field] != nil {
-					r.Value, r.State, r.ValueExists = n.Values[s.field], n.State[s.field], true
+				} else if n := msg.Put[parentSoul]; n != nil {
+					if newVal, ok := n.Values[s.field]; ok {
+						newState := n.State[s.field]
+						// Dedupe the value
+						if lastSeenValue == newVal && lastSeenState == newState {
+							continue
+						}
+						// If we're storing only what we requested (we do "everything" at a higher level), do it here
+						// and only send result if it was an update. Otherwise only do it if we would have done one.
+						confRes := ConflictResolutionNeverSeenUpdate
+						if s.gun.tracking == TrackingRequested {
+							confRes, r.Err = s.gun.storage.Put(ctx, parentSoul, s.field, newVal, newState, false)
+						} else if lastSeenState > 0 {
+							confRes = ConflictResolve(lastSeenValue, lastSeenState, newVal, newState, StateNow())
+						}
+						// If there are no errors and it was an update, update the last seen and set the response vals
+						if r.Err == nil && confRes.IsImmediateUpdate() {
+							lastSeenValue, lastSeenState = newVal, newState
+							r.Value, r.State, r.ValueExists = newVal, newState, true
+						}
+					}
 				}
-				// TODO: conflict resolution and defer
-				// TODO: dedupe
-				// TODO: store and cache
 				safeFetchResultSend(ch, r)
 			}
 		}

gun/scoped_put.go

@@ -87,14 +87,10 @@ func (s *Scoped) Put(ctx context.Context, val Value, opts ...PutOption) <-chan *
 			// Also store locally and set the cached soul
 			// TODO: Should I not store until the very end just in case it errors halfway
 			// though? There are no standard cases where it should fail.
-			if ok, err := s.gun.storage.Put(ctx, prevParentSoul, parent.field, ValueRelation(parentCachedSoul), currState); err != nil {
+			if _, err := s.gun.storage.Put(ctx, prevParentSoul, parent.field, ValueRelation(parentCachedSoul), currState, false); err != nil {
 				ch <- &PutResult{Err: err}
 				close(ch)
 				return ch
-			} else if !ok {
-				ch <- &PutResult{Err: fmt.Errorf("Unexpected deferred local store")}
-				close(ch)
-				return ch
 			} else if !parent.setCachedSoul(ValueRelation(parentCachedSoul)) {
 				ch <- &PutResult{Err: fmt.Errorf("Concurrent cached soul set")}
 				close(ch)
@@ -104,14 +100,10 @@ func (s *Scoped) Put(ctx context.Context, val Value, opts ...PutOption) <-chan *
 		prevParentSoul = parentCachedSoul
 	}
 	// Now that we've setup all the parents, we can do this store locally
-	if ok, err := s.gun.storage.Put(ctx, prevParentSoul, s.field, val, currState); err != nil {
+	if _, err := s.gun.storage.Put(ctx, prevParentSoul, s.field, val, currState, false); err != nil {
 		ch <- &PutResult{Err: err}
 		close(ch)
 		return ch
-	} else if !ok {
-		ch <- &PutResult{Err: fmt.Errorf("Unexpected deferred local store")}
-		close(ch)
-		return ch
 	}
 	// We need an ack for local store and stop if local only
 	ch <- &PutResult{}

gun/state.go

@@ -1,7 +1,8 @@
 package gun
 
 import (
-	"sync/atomic"
+	"bytes"
+	"encoding/json"
 	"time"
 )
 
@@ -9,42 +10,40 @@ type State uint64
 
 func StateNow() State { return State(timeNowUnixMs()) }
 
-// timeFromUnixMs returns zero'd time if ms is 0
-func timeFromUnixMs(ms int64) time.Time {
-	if ms == 0 {
-		return time.Time{}
-	}
-	return time.Unix(0, ms*int64(time.Millisecond))
+func StateFromTime(t time.Time) State { return State(timeToUnixMs(t)) }
+
+type ConflictResolution int
+
+const (
+	ConflictResolutionNeverSeenUpdate ConflictResolution = iota
+	ConflictResolutionTooFutureDeferred
+	ConflictResolutionOlderHistorical
+	ConflictResolutionNewerUpdate
+	ConflictResolutionSameKeep
+	ConflictResolutionSameUpdate
+)
+
+func (c ConflictResolution) IsImmediateUpdate() bool {
+	return c == ConflictResolutionNeverSeenUpdate || c == ConflictResolutionNewerUpdate || c == ConflictResolutionSameUpdate
 }
 
-// timeToUnixMs returns 0 if t.IsZero
-func timeToUnixMs(t time.Time) int64 {
-	if t.IsZero() {
-		return 0
-	}
-	return t.UnixNano() / int64(time.Millisecond)
-}
-
-func timeNowUnixMs() int64 {
-	return timeToUnixMs(time.Now())
-}
-
-var lastNano int64
-
-// uniqueNano is 0 if ms is first time seen, otherwise a unique num in combination with ms
-func timeNowUniqueUnix() (ms int64, uniqueNum int64) {
-	now := time.Now()
-	newNano := now.UnixNano()
-	for {
-		prevLastNano := lastNano
-		if prevLastNano < newNano && atomic.CompareAndSwapInt64(&lastNano, prevLastNano, newNano) {
-			ms = newNano / int64(time.Millisecond)
-			// If was same ms as seen before, set uniqueNum to the nano part
-			if prevLastNano/int64(time.Millisecond) == ms {
-				uniqueNum = newNano%int64(time.Millisecond) + 1
-			}
-			return
-		}
-		newNano = prevLastNano + 1
+func ConflictResolve(existingVal Value, existingState State, newVal Value, newState State, sysState State) ConflictResolution {
+	// Existing gunjs impl serializes to JSON first to do lexical comparisons, so we will too
+	if sysState < newState {
+		return ConflictResolutionTooFutureDeferred
+	} else if newState < existingState {
+		return ConflictResolutionOlderHistorical
+	} else if existingState < newState {
+		return ConflictResolutionNewerUpdate
+	} else if existingVal == newVal {
+		return ConflictResolutionSameKeep
+	} else if existingJSON, err := json.Marshal(existingVal); err != nil {
+		panic(err)
+	} else if newJSON, err := json.Marshal(newVal); err != nil {
+		panic(err)
+	} else if bytes.Compare(existingJSON, newJSON) < 0 {
+		return ConflictResolutionSameUpdate
+	} else {
+		return ConflictResolutionSameKeep
 	}
 }

gun/storage.go

@@ -4,19 +4,21 @@ import (
 	"context"
 	"errors"
 	"sync"
+	"time"
 )
 
 var ErrStorageNotFound = errors.New("Not found")
 
 type Storage interface {
 	Get(ctx context.Context, parentSoul, field string) (Value, State, error)
-	// If bool is false, it's deferred
-	Put(ctx context.Context, parentSoul, field string, val Value, state State) (bool, error)
-	Tracking(ctx context.Context, parentSoul, field string) (bool, error)
+	Put(ctx context.Context, parentSoul, field string, val Value, state State, onlyIfExists bool) (ConflictResolution, error)
+	Close() error
 }
 
-type StorageInMem struct {
-	values sync.Map
+type storageInMem struct {
+	values        map[parentSoulAndField]*valueWithState
+	valueLock     sync.RWMutex
+	purgeCancelFn context.CancelFunc
 }
 
 type parentSoulAndField struct{ parentSoul, field string }
@@ -26,22 +28,75 @@ type valueWithState struct {
 	state State
 }
 
-func (s *StorageInMem) Get(ctx context.Context, parentSoul, field string) (Value, State, error) {
-	v, ok := s.values.Load(parentSoulAndField{parentSoul, field})
-	if !ok {
-		return nil, 0, ErrStorageNotFound
+func NewStorageInMem(oldestAllowed time.Duration) Storage {
+	s := &storageInMem{values: map[parentSoulAndField]*valueWithState{}}
+	// Start the purger
+	if oldestAllowed > 0 {
+		var ctx context.Context
+		ctx, s.purgeCancelFn = context.WithCancel(context.Background())
+		go func() {
+			tick := time.NewTicker(5 * time.Second)
+			defer tick.Stop()
+			for {
+				select {
+				case <-ctx.Done():
+					return
+				case t := <-tick.C:
+					oldestStateAllowed := StateFromTime(t.Add(-oldestAllowed))
+					s.valueLock.Lock()
+					s.valueLock.Unlock()
+					for k, v := range s.values {
+						if v.state < oldestStateAllowed {
+							delete(s.values, k)
 						}
-	vs := v.(*valueWithState)
+					}
+				}
+			}
+		}()
+	}
+	return s
+}
+
+func (s *storageInMem) Get(ctx context.Context, parentSoul, field string) (Value, State, error) {
+	s.valueLock.RLock()
+	defer s.valueLock.RUnlock()
+	if vs := s.values[parentSoulAndField{parentSoul, field}]; vs == nil {
+		return nil, 0, ErrStorageNotFound
+	} else {
 		return vs.val, vs.state, nil
 	}
-
-func (s *StorageInMem) Put(ctx context.Context, parentSoul, field string, val Value, state State) (bool, error) {
-	s.values.Store(parentSoulAndField{parentSoul, field}, &valueWithState{val, state})
-	// TODO: conflict resolution state check?
-	return true, nil
 }
 
-func (s *StorageInMem) Tracking(ctx context.Context, parentSoul, field string) (bool, error) {
-	_, ok := s.values.Load(parentSoulAndField{parentSoul, field})
-	return ok, nil
+func (s *storageInMem) Put(
+	ctx context.Context, parentSoul, field string, val Value, state State, onlyIfExists bool,
+) (confRes ConflictResolution, err error) {
+	s.valueLock.Lock()
+	defer s.valueLock.Unlock()
+	key, newVs := parentSoulAndField{parentSoul, field}, &valueWithState{val, state}
+	sysState := StateNow()
+	if existingVs := s.values[key]; existingVs == nil && onlyIfExists {
+		return 0, ErrStorageNotFound
+	} else if existingVs == nil {
+		confRes = ConflictResolutionNeverSeenUpdate
+	} else {
+		confRes = ConflictResolve(existingVs.val, existingVs.state, val, state, sysState)
+	}
+	if confRes == ConflictResolutionTooFutureDeferred {
+		// Schedule for 100ms past when it's deferred to
+		time.AfterFunc(time.Duration(state-sysState)*time.Millisecond+100, func() {
+			// TODO: should I check whether closed?
+			// TODO: what to do w/ error?
+			s.Put(ctx, parentSoul, field, val, state, onlyIfExists)
+		})
+	} else if confRes.IsImmediateUpdate() {
+		s.values[key] = newVs
+	}
+	return
+}
+
+func (s *storageInMem) Close() error {
+	if s.purgeCancelFn != nil {
+		s.purgeCancelFn()
+	}
+	return nil
 }

gun/tests/gun_test.go

@@ -9,8 +9,10 @@ import (
 
 func TestGunGetSimple(t *testing.T) {
 	// Run the server, put in one call, get in another, then check
-	ctx, cancelFn := newContextWithGunJServer(t)
+	ctx, cancelFn := newContext(t)
 	defer cancelFn()
+	serverCancelFn := ctx.startGunJSServer()
+	defer serverCancelFn()
 	randStr := randString(30)
 	// Write w/ JS
 	ctx.runJSWithGun(`
@@ -29,11 +31,12 @@ func TestGunGetSimple(t *testing.T) {
 	r := g.Scoped(ctx, "esgopeta-test", "TestGunGetSimple", "some-key").FetchOne(ctx)
 	ctx.Require.NoError(r.Err)
 	ctx.Require.Equal(gun.ValueString(randStr), r.Value.(gun.ValueString))
-	// // Do it again TODO: make sure there are no network calls, it's all from mem
-	// ctx.debugf("Asking for key again")
-	// f = g.Scoped(ctx, "esgopeta-test", "TestGunGetSimple", "some-key").FetchOne(ctx)
-	// ctx.Require.NoError(f.Err)
-	// ctx.Require.Equal(gun.ValueString(randStr), f.Value.(gun.ValueString))
+	// Do it again with the JS server closed since it should fetch from memory
+	serverCancelFn()
+	ctx.debugf("Asking for key again")
+	r = g.Scoped(ctx, "esgopeta-test", "TestGunGetSimple", "some-key").FetchOne(ctx)
+	ctx.Require.NoError(r.Err)
+	ctx.Require.Equal(gun.ValueString(randStr), r.Value.(gun.ValueString))
 }
 
 func TestGunPutSimple(t *testing.T) {
@@ -59,3 +62,12 @@ func TestGunPutSimple(t *testing.T) {
 	`)
 	ctx.Require.Equal(randStr, strings.TrimSpace(string(out)))
 }
+
+/*
+TODO Tests to write:
+* test put w/ future state happens then
+* test put w/ old state is discarded
+* test put w/ new state is persisted
+* test put w/ same state but greater is persisted
+* test put w/ same state but less is discarded
+*/

gun/util.go

@@ -2,6 +2,8 @@ package gun
 
 import (
 	"crypto/rand"
+	"sync/atomic"
+	"time"
 )
 
 const randChars = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
@@ -17,3 +19,43 @@ func randString(n int) (s string) {
 	}
 	return s
 }
+
+// timeFromUnixMs returns zero'd time if ms is 0
+func timeFromUnixMs(ms int64) time.Time {
+	if ms == 0 {
+		return time.Time{}
+	}
+	return time.Unix(0, ms*int64(time.Millisecond))
+}
+
+// timeToUnixMs returns 0 if t.IsZero
+func timeToUnixMs(t time.Time) int64 {
+	if t.IsZero() {
+		return 0
+	}
+	return t.UnixNano() / int64(time.Millisecond)
+}
+
+func timeNowUnixMs() int64 {
+	return timeToUnixMs(time.Now())
+}
+
+var lastNano int64
+
+// uniqueNano is 0 if ms is first time seen, otherwise a unique num in combination with ms
+func timeNowUniqueUnix() (ms int64, uniqueNum int64) {
+	now := time.Now()
+	newNano := now.UnixNano()
+	for {
+		prevLastNano := lastNano
+		if prevLastNano < newNano && atomic.CompareAndSwapInt64(&lastNano, prevLastNano, newNano) {
+			ms = newNano / int64(time.Millisecond)
+			// If was same ms as seen before, set uniqueNum to the nano part
+			if prevLastNano/int64(time.Millisecond) == ms {
+				uniqueNum = newNano%int64(time.Millisecond) + 1
+			}
+			return
+		}
+		newNano = prevLastNano + 1
+	}
+}