Switch FSTLevelDBQueryCache to use transactions (#942)

* Start work on leveldb transactions

* Style

* Working API. Not plumbed in yet

* Move files into correct place

* Wrangling file locations and associations

* Tests pass

* Add some comments

* style

* Fix copyright

* Rewrite iterator internals to handle deletion-while-iterating. Also add tests for same

* Switch to strings instead of slices

* Style

* More style fixes

* Start switching writegroup over

* Swap out write group tracking for transaction usage

* Style

* Response to feedback before updating docs

* Style

* Add comment

* Initialize version_

* Satisfy the linter

* Start switching writegroup over

* Swap out write group tracking for transaction usage

* Style

* Checkpoint before implementing BatchDescription

* Style

* Initial plumbing for leveldb local parts

* Add model::BatchId

* Port leveldb_key.{h,cc}

* Add string StartsWith

* Add leveldb_key_test.cc to the project

* Revert back to using leveldb::Slice for read/describe

These operations universally operate on keys obtained from leveldb so
it's actually unhelpful to force all the callers to make
absl::string_views from them.

* Everything passing

* Drop unused function

* Style

* STart work on reads

* Swap reads in queryCache to use transactions

* Fix up tests of querycache

* Drop commented out code

* Cleanup

* Style

* Fix up for passing tests

* style

* Renaming

* Style

* Start work on ToString for transactions

* Add ToString() method to LevelDbTransaction

* Style

* lint

* Fix includes, drop runTransaction

* current_transaction -> currentTransaction

* LevelDbTransaction::NewIterator now returns a unique_ptr

* Style

* Revert addition of util::StartsWith

* Add log line

* Style

* Add log line

* Style

* Add debug log line for commits, drop unused BatchDescription

* Fix an include, but mostly try to trigger a travis build

1 files changed, 4 insertions, 4 deletions

diff --git a/Firestore/Example/Tests/Local/FSTLevelDBTransactionTests.mm b/Firestore/Example/Tests/Local/FSTLevelDBTransactionTests.mm
index 2a1efb0..c959b4f 100644
--- a/Firestore/Example/Tests/Local/FSTLevelDBTransactionTests.mm
+++ b/Firestore/Example/Tests/Local/FSTLevelDBTransactionTests.mm
@@ -62,7 +62,7 @@ using firebase::firestore::local::LevelDbTransaction;
   std::string key = "key1";
 
   transaction.Put(key, "value");
-  std::unique_ptr<LevelDbTransaction::Iterator> iter(transaction.NewIterator());
+  auto iter = transaction.NewIterator();
   iter->Seek(key);
   XCTAssertEqual(key, iter->key());
   iter->Next();
@@ -212,7 +212,7 @@ using firebase::firestore::local::LevelDbTransaction;
     transaction.Put("key_" + std::to_string(i), "value_" + std::to_string(i));
   }
 
-  std::unique_ptr<LevelDbTransaction::Iterator> it(transaction.NewIterator());
+  auto it = transaction.NewIterator();
   it->Seek("key_0");
   for (int i = 0; i < 4; ++i) {
     XCTAssertTrue(it->Valid());
@@ -234,7 +234,7 @@ using firebase::firestore::local::LevelDbTransaction;
 
   // Create a transaction, iterate, deleting key_0. Verify we still iterate key_1.
   LevelDbTransaction transaction(_db.get());
-  std::unique_ptr<LevelDbTransaction::Iterator> it(transaction.NewIterator());
+  auto it = transaction.NewIterator();
   it->Seek("key_0");
   XCTAssertTrue(it->Valid());
   XCTAssertEqual("key_0", it->key());
@@ -256,7 +256,7 @@ using firebase::firestore::local::LevelDbTransaction;
 
   // Create a transaction, iterate to key_1, delete key_2. Verify we still iterate key_3.
   LevelDbTransaction transaction(_db.get());
-  std::unique_ptr<LevelDbTransaction::Iterator> it(transaction.NewIterator());
+  auto it = transaction.NewIterator();
   it->Seek("key_0");
   XCTAssertTrue(it->Valid());
   XCTAssertEqual("key_0", it->key());