From 5d38a3512d4a68f912f68e91093b39efc97f55f1 Mon Sep 17 00:00:00 2001 From: Greg Soltis Date: Mon, 26 Mar 2018 14:29:51 -0700 Subject: Running a transaction (#969) * 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 * STart work on reads * Swap reads in queryCache to use transactions * Start on remote documents * Transition mutation queue and remote documents to use transactions * Style * Make everything pass * Make everything pass * Make it compile * Style * Style * Revert name change, use DefaultReadOptions() * Style * Example of running a transaction with a lambda * Drop errant typo * Drop duplicate method declarations * replace usage of auto w/ decltype * Drop an unnecessary _Nullable. Add some nullability warning suppression * use absl::make_unique, handle void return type * Style * Wrap backing persistence and expectation of backing persistence for transaction runner into a method * More comments, trigger CI --- Firestore/Source/Local/FSTPersistence.h | 78 +++++++++++++++++++++++++++++++++ 1 file changed, 78 insertions(+) (limited to 'Firestore/Source/Local/FSTPersistence.h') diff --git a/Firestore/Source/Local/FSTPersistence.h b/Firestore/Source/Local/FSTPersistence.h index 30eb211..6f75d73 100644 --- a/Firestore/Source/Local/FSTPersistence.h +++ b/Firestore/Source/Local/FSTPersistence.h @@ -16,6 +16,7 @@ #import +#import "Firestore/Source/Util/FSTAssert.h" #include "Firestore/core/src/firebase/firestore/auth/user.h" @class FSTWriteGroup; @@ -55,6 +56,7 @@ NS_ASSUME_NONNULL_BEGIN * FSTPersistence. The cost is that the FSTLocalStore needs to be slightly careful about the order * of its reads and writes in order to avoid relying on being able to read back uncommitted writes. */ +struct FSTTransactionRunner; @protocol FSTPersistence /** @@ -99,6 +101,82 @@ NS_ASSUME_NONNULL_BEGIN */ - (void)commitGroup:(FSTWriteGroup *)group; +@property(nonatomic, readonly, assign) const FSTTransactionRunner &run; + +@end + +@protocol FSTTransactional + +- (void)startTransaction; + +- (void)commitTransaction; + @end +struct FSTTransactionRunner { +// Intentionally disable nullability checking for this function. We cannot properly annotate +// the function because this function can handle both pointer and non-pointer types. It is an error +// to annotate non-pointer types with a nullability annotation. +#pragma clang diagnostic push +#pragma clang diagnostic ignored "-Wnullability-completeness" + + /** + * The following two functions handle accepting callables and optionally running them within a + * transaction. Persistence layers that conform to the FSTTransactional protocol can set + * themselves as the backing persistence for a transaction runner, in which case a transaction + * will be started before a block is run, and committed after the block has executed. If there is + * no backing instance of FSTTransactional, the block will be run directly. + * + * There are two instances of operator() to handle the case where the block returns void, rather + * than a type. + * + * The transaction runner keeps a weak reference to the backing persistence so as not to cause a + * retain cycle. The reference is upgraded to strong (with a fatal error if it has disappeared) + * for the duration of running a transaction. + */ + + template + auto operator()(F block) -> + typename std::enable_if::value, void>::type { + __strong id strongDb = _db; + if (!strongDb && _expect_db) { + FSTCFail(@"Transaction runner accessed without underlying db when it expected one"); + } + if (strongDb) { + [strongDb startTransaction]; + } + block(); + if (strongDb) { + [strongDb commitTransaction]; + } + } + + template + auto operator()(F block) const -> + typename std::enable_if::value, decltype(block())>::type { + using ReturnT = decltype(block()); + __strong id strongDb = _db; + if (!strongDb && _expect_db) { + FSTCFail(@"Transaction runner accessed without underlying db when it expected one"); + } + if (strongDb) { + [strongDb startTransaction]; + } + ReturnT result = block(); + if (strongDb) { + [strongDb commitTransaction]; + } + return result; + } +#pragma clang diagnostic pop + void SetBackingPersistence(id db) { + _db = db; + _expect_db = true; + } + + private: + __weak id _db; + bool _expect_db = false; +}; + NS_ASSUME_NONNULL_END -- cgit v1.2.3