fix rapid barrier use

server/pkg/server/server.go

@@ -32,7 +32,7 @@ func (sd *safeDoc) Perform(in InPacket, handleID, clientID int) (ok bool, err er
 	sd.lock.Lock()
 	defer sd.lock.Unlock()
 
-	if !sd.doc.Barrier(in.TargetVersion, in.Barrier) {
+	if !sd.doc.Barrier(handleID, in.TargetVersion, in.Barrier) {
 		// not an error - failed to pass barrier
 		// TODO: we don't explicitly announce this - expect client to know
 		return

server/pkg/ylayer/doc.go

@@ -147,23 +147,14 @@ func (d *docImpl) Read() (dw *DocWork) {
 	return
 }
 
-// inoToVersion returns the high version for the specific inode.
-// This is for the caller to check whether work can be applied (check barrier).
-func (d *docImpl) inoToVersion(ino string) (version int) {
-	nh := d.byIno[ino]
-	if nh == nil {
-		return 0
-	}
-	_, version = nh.versionRange()
-	return
-}
-
-func (d *docImpl) Barrier(targetVersion int, inos []string) (ok bool) {
-	if targetVersion <= 0 {
-		return true
-	}
+func (d *docImpl) Barrier(handle, targetVersion int, inos []string) (ok bool) {
 	for _, ino := range inos {
-		if d.inoToVersion(ino) > targetVersion {
+		nh := d.byIno[ino]
+		if nh == nil {
+			continue
+		}
+
+		if !nh.allowBarrier(handle, targetVersion) {
 			return false
 		}
 	}

server/pkg/ylayer/node.go

@@ -30,15 +30,17 @@ type nodeHolder struct {
 	dataAt int             // when was data last flattened
 	data   GumnutDataArray // data at dataAt
 
+	prune   bool           // if history is not exhaustive
 	history []historyEntry // history over time
 	length  int            // current length
 }
 
-func (fn *nodeHolder) versionRange() (lo, hi int) {
-	if len(fn.history) == 0 {
-		return 0, 0
+func (fn *nodeHolder) versionRange() (prune bool, lo, hi int) {
+	if len(fn.history) != 0 {
+		lo, hi = fn.history[0].version, fn.history[len(fn.history)-1].version
 	}
-	return fn.history[0].version, fn.history[len(fn.history)-1].version
+	prune = fn.prune
+	return
 }
 
 // read moves the current "live" version here forward to the given version number.
@@ -97,6 +99,27 @@ func (nh *nodeHolder) clearHandle(handle int) (change bool) {
 	return
 }
 
+// allowBarrier checks that the handle with the given target is "as they see it".
+// i.e., there are only ops past the target which the handle created.
+func (n *nodeHolder) allowBarrier(handle, targetVersion int) (allow bool) {
+	prune, lo, _ := n.versionRange()
+	if prune && targetVersion < lo {
+		return false
+	}
+
+	// look for the first entry that is > the known version
+	idx := sort.Search(len(n.history), func(i int) (match bool) {
+		return n.history[i].version > targetVersion
+	})
+
+	for _, entry := range n.history[idx:] {
+		if handle != entry.handle {
+			return false
+		}
+	}
+	return true
+}
+
 func (nh *nodeHolder) historyFrom(version, handle int) (out []ymodel.PriorOpSelf) {
 	// look for the first entry that is > the known version
 	idx := sort.Search(len(nh.history), func(i int) (match bool) {
@@ -128,8 +151,8 @@ type prepareResult struct {
 // prepare generates the updated state we should apply to this nodeHolder after this Patch.
 // This is so doc can apply ops on many nodes at once.
 func (nh *nodeHolder) prepare(arg prepareArg, p *Patch) (res prepareResult, err error) {
-	lo, hi := nh.versionRange()
-	if arg.targetVersion > 0 && arg.targetVersion < lo {
+	prune, lo, hi := nh.versionRange()
+	if prune && arg.targetVersion > 0 && arg.targetVersion < lo {
 		err = ErrVersion
 		return // must be within known range - but we don't check hi, assume host has
 	}

server/pkg/ylayer/types.go

@@ -18,9 +18,9 @@ type Doc interface {
 	// Internally, this may apply ops forward: we don't always keep a "live" copy around.
 	Read() (dw *DocWork)
 
-	// Barrier returns true if the given client can pass the barrier with the given inos and their known target version.
+	// Barrier returns true if the given handle can pass the barrier with the given inos and their known target version.
 	// This is effectively checking all the target inos have not changed since ...
-	Barrier(targetVersion int, inos []string) (ok bool)
+	Barrier(handle, targetVersion int, inos []string) (ok bool)
 
 	// ClearHandle removes the given handle from known history.
 	ClearHandle(handleID int) (change bool)

tests/integration/data.test.ts

@@ -13,12 +13,12 @@ test('data', async (t) => {
 
   data1.root().set('abc', 'hello');
   data1.root().set('abc', 'hello123');
-  // data1.root().set('def', data1.root()); // FIXME: this is failing to apply over itself - seq3
+  data1.root().set('def', data1.root());
 
   await checkCond(() => {
     const root = data2.root();
 
     assert.strictEqual(root.get('abc'), 'hello123');
-    // assert.strictEqual(root.get('def'), root);
+    assert.strictEqual(root.get('def'), root);
   });
 });