Bump sequence numbers when receiving a new resume token (#1214)

* Bump sequence number on resume token refresh

* Style

* Fix comment formatting

4 files changed, 24 insertions, 14 deletions

diff --git a/Firestore/Source/Local/FSTLocalStore.mm b/Firestore/Source/Local/FSTLocalStore.mm
index 3a324cd..92462f0 100644
--- a/Firestore/Source/Local/FSTLocalStore.mm
+++ b/Firestore/Source/Local/FSTLocalStore.mm
@@ -262,6 +262,7 @@ NS_ASSUME_NONNULL_BEGIN
 
 - (FSTMaybeDocumentDictionary *)applyRemoteEvent:(FSTRemoteEvent *)remoteEvent {
   return self.persistence.run("Apply remote event", [&]() -> FSTMaybeDocumentDictionary * {
+    FSTListenSequenceNumber sequenceNumber = [self.listenSequence next];
     id<FSTQueryCache> queryCache = self.queryCache;
 
     [remoteEvent.targetChanges enumerateKeysAndObjectsUsingBlock:^(
@@ -274,6 +275,18 @@ NS_ASSUME_NONNULL_BEGIN
         return;
       }
 
+      // Update the resume token if the change includes one. Don't clear any preexisting value.
+      // Bump the sequence number as well, so that documents being removed now are ordered later
+      // than documents that were previously removed from this target.
+      NSData *resumeToken = change.resumeToken;
+      if (resumeToken.length > 0) {
+        queryData = [queryData queryDataByReplacingSnapshotVersion:change.snapshotVersion
+                                                       resumeToken:resumeToken
+                                                    sequenceNumber:sequenceNumber];
+        self.targetIDs[targetIDNumber] = queryData;
+        [self.queryCache updateQueryData:queryData];
+      }
+
       FSTTargetMapping *mapping = change.mapping;
       if (mapping) {
         // First make sure that all references are deleted.
@@ -291,15 +304,6 @@ NS_ASSUME_NONNULL_BEGIN
           FSTFail(@"Unknown mapping type: %@", mapping);
         }
       }
-
-      // Update the resume token if the change includes one. Don't clear any preexisting value.
-      NSData *resumeToken = change.resumeToken;
-      if (resumeToken.length > 0) {
-        queryData = [queryData queryDataByReplacingSnapshotVersion:change.snapshotVersion
-                                                       resumeToken:resumeToken];
-        self.targetIDs[targetIDNumber] = queryData;
-        [self.queryCache updateQueryData:queryData];
-      }
     }];
 
     // TODO(klimt): This could probably be an NSMutableDictionary.
diff --git a/Firestore/Source/Local/FSTQueryData.h b/Firestore/Source/Local/FSTQueryData.h
index d2dacd6..bde0a15 100644
--- a/Firestore/Source/Local/FSTQueryData.h
+++ b/Firestore/Source/Local/FSTQueryData.h
@@ -54,10 +54,14 @@ typedef NS_ENUM(NSInteger, FSTQueryPurpose) {
 
 - (instancetype)init NS_UNAVAILABLE;
 
-/** Creates a new query data instance with an updated snapshot version and resume token. */
+/**
+ * Creates a new query data instance with an updated snapshot version, resume token, and sequence
+ * number.
+ */
 - (instancetype)queryDataByReplacingSnapshotVersion:
                     (firebase::firestore::model::SnapshotVersion)snapshotVersion
-                                        resumeToken:(NSData *)resumeToken;
+                                        resumeToken:(NSData *)resumeToken
+                                     sequenceNumber:(FSTListenSequenceNumber)sequenceNumber;
 
 /** The latest snapshot version seen for this target. */
 - (const firebase::firestore::model::SnapshotVersion &)snapshotVersion;
diff --git a/Firestore/Source/Local/FSTQueryData.mm b/Firestore/Source/Local/FSTQueryData.mm
index e352101..5087dfc 100644
--- a/Firestore/Source/Local/FSTQueryData.mm
+++ b/Firestore/Source/Local/FSTQueryData.mm
@@ -95,10 +95,11 @@ NS_ASSUME_NONNULL_BEGIN
 }
 
 - (instancetype)queryDataByReplacingSnapshotVersion:(SnapshotVersion)snapshotVersion
-                                        resumeToken:(NSData *)resumeToken {
+                                        resumeToken:(NSData *)resumeToken
+                                     sequenceNumber:(FSTListenSequenceNumber)sequenceNumber {
   return [[FSTQueryData alloc] initWithQuery:self.query
                                     targetID:self.targetID
-                        listenSequenceNumber:self.sequenceNumber
+                        listenSequenceNumber:sequenceNumber
                                      purpose:self.purpose
                              snapshotVersion:std::move(snapshotVersion)
                                  resumeToken:resumeToken];
diff --git a/Firestore/Source/Remote/FSTRemoteStore.mm b/Firestore/Source/Remote/FSTRemoteStore.mm
index c1ec9ff..d15d2e5 100644
--- a/Firestore/Source/Remote/FSTRemoteStore.mm
+++ b/Firestore/Source/Remote/FSTRemoteStore.mm
@@ -448,7 +448,8 @@ static const int kMaxPendingWrites = 10;
       if (queryData) {
         self->_listenTargets[target] =
             [queryData queryDataByReplacingSnapshotVersion:change.snapshotVersion
-                                               resumeToken:resumeToken];
+                                               resumeToken:resumeToken
+                                            sequenceNumber:queryData.sequenceNumber];
       }
     }
   }];