Add option to allow SDK create cache indexes automatically to improve query execution locally

[cherylEnkidu]

Preparing work for index auto creation feature.
#no-changelog

[google-oss-bot]

Size Report ¹

Affected Products

• FirebaseFirestore

  Type	Base (3df15ba)	Merge (a3ff892)	Diff
  CocoaPods	?	-51.5 kB	? (?)

Test Logs

• Merge (a3ff892): https://github.com/firebase/firebase-ios-sdk/actions/runs/5835642429

1. https://storage.googleapis.com/firebase-sdk-metric-reports/NT3XGjxxDM.html

[google-oss-bot]

Coverage Report ¹

Affected Products

• FirebaseFirestore-iOS-FirebaseFirestore.framework

  Overall coverage changed from 88.12% (2e7eecd) to 88.14% (5180393) by +0.02%.

  17 individual files with coverage change

  Filename	Base (2e7eecd)	Merge (5180393)	Diff
  exception.cc	84.21%	23.68%	-60.53%
  firestore.cc	92.13%	92.41%	+0.28%
  firestore_client.cc	98.91%	98.94%	+0.03%
  FIRFirestore.mm	88.70%	88.97%	+0.27%
  FIRPersistentCacheIndexManager.mm	?	100.00%	?
  leveldb_index_manager.cc	97.67%	97.72%	+0.06%
  leveldb_key.cc	98.14%	98.82%	+0.69%
  leveldb_opener.cc	76.81%	78.99%	+2.17%
  leveldb_persistence.cc	90.82%	92.31%	+1.49%
  leveldb_remote_document_cache.cc	96.41%	96.55%	+0.14%
  local_documents_view.cc	96.86%	96.92%	+0.06%
  memory_index_manager.cc	50.00%	51.61%	+1.61%
  memory_persistence.cc	100.00%	97.37%	-2.63%
  memory_remote_document_cache.cc	93.51%	93.83%	+0.32%
  persistent_cache_index_manager.cc	?	100.00%	?
  query_engine.cc	98.28%	98.68%	+0.40%
  target_index_matcher.cc	97.80%	95.28%	-2.53%

Test Logs

• Base (2e7eecd): https://github.com/firebase/firebase-ios-sdk/actions/runs/5978090256
• Merge (5180393): https://github.com/firebase/firebase-ios-sdk/actions/runs/6003780403

1. https://storage.googleapis.com/firebase-sdk-metric-reports/DMi2ycmIRI.html

[wu-hui]

Half way through, l reviewed all the non-tests, there are some minor changes requested.

[wu-hui]

Couple more small nits, I am approving it however.

[mikehardy]

This looks neat! Was checking documentation for possible integration in react-native-firebase and I may be wrong, but is the documentation for the API in sync?

I see the API in use here:
https://github.com/firebase/firebase-ios-sdk/pull/11596/files#diff-9f6f97afe1406491a0af86b5751973e5908e45e73ee5a698445157b6e67f0f9eR172-R191

And I see a mention of the API here as the thing to use in future: https://firebase.google.com/docs/reference/ios/firebasefirestore/api/reference/Classes/FIRFirestore#-setindexconfigurationfromjson:completion:

But I'm unable to find docs on the web for this object PersistentCacheIndexManager or it's methods