From 5ada17a2fefb97a40e0aee9c6407291470681866 Mon Sep 17 00:00:00 2001 From: Marek Gilbert Date: Wed, 18 Jul 2018 14:34:54 -0700 Subject: [PATCH] Allow remote updates from watch to heal a cache with synthesized deletes in it Port of https://github.com/firebase/firebase-js-sdk/pull/1015 Addresses #1548 --- Firestore/Source/Local/FSTLocalStore.mm | 29 ++++++++++++++++++++----- 1 file changed, 24 insertions(+), 5 deletions(-) diff --git a/Firestore/Source/Local/FSTLocalStore.mm b/Firestore/Source/Local/FSTLocalStore.mm index 6aab78e8b6e6..aa3534e29330 100644 --- a/Firestore/Source/Local/FSTLocalStore.mm +++ b/Firestore/Source/Local/FSTLocalStore.mm @@ -268,6 +268,7 @@ - (FSTMaybeDocumentDictionary *)applyRemoteEvent:(FSTRemoteEvent *)remoteEvent { FSTListenSequenceNumber sequenceNumber = [self.listenSequence next]; id queryCache = self.queryCache; + DocumentKeySet authoritativeUpdates; for (const auto &entry : remoteEvent.targetChanges) { FSTTargetID targetID = entry.first; FSTBoxedTargetID *boxedTargetID = @(targetID); @@ -279,6 +280,21 @@ - (FSTMaybeDocumentDictionary *)applyRemoteEvent:(FSTRemoteEvent *)remoteEvent { continue; } + // When a global snapshot contains updates (either add or modify) we can completely trust + // these updates as authoritative and blindly apply them to our cache (as a defensive measure + // to promote self-healing in the unfortunate case that our cache is ever somehow corrupted / + // out-of-sync). + // + // If the document is only updated while removing it from a target then watch isn't obligated + // to send the absolute latest version: it can send the first version that caused the document + // not to match. + for (const DocumentKey& key : change.addedDocuments) { + authoritativeUpdates = authoritativeUpdates.insert(key); + } + for (const DocumentKey& key : change.modifiedDocuments) { + authoritativeUpdates = authoritativeUpdates.insert(key); + } + [queryCache removeMatchingKeys:change.removedDocuments forTargetID:targetID]; [queryCache addMatchingKeys:change.addedDocuments forTargetID:targetID]; @@ -303,11 +319,14 @@ - (FSTMaybeDocumentDictionary *)applyRemoteEvent:(FSTRemoteEvent *)remoteEvent { FSTMaybeDocument *doc = kv.second; changedDocKeys = changedDocKeys.insert(key); FSTMaybeDocument *existingDoc = [self.remoteDocumentCache entryForKey:key]; - // Make sure we don't apply an old document version to the remote cache, though we - // make an exception for SnapshotVersion::None() which can happen for manufactured - // events (e.g. in the case of a limbo document resolution failing). - if (!existingDoc || SnapshotVersion{doc.version} == SnapshotVersion::None() || - SnapshotVersion{doc.version} >= SnapshotVersion{existingDoc.version}) { + + // If a document update isn't authoritative, make sure we don't apply an old document version + // to the remote cache. We make an exception for SnapshotVersion.MIN which can happen for + // manufactured events (e.g. in the case of a limbo document resolution failing). + if (!existingDoc || + doc.version == SnapshotVersion::None() || + authoritativeUpdates.contains(doc.key) || + doc.version >= existingDoc.version) { [self.remoteDocumentCache addEntry:doc]; } else { LOG_DEBUG( pFad - Phonifier reborn

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