Rename canRecoverFromDisconnect() in order to better describe
its function. Make it use the transaction ID and query walltime
as arguments and return an ERR_* class constant instead of a bool.
Avoid retries of slow queries that yield lost connection errors.
Add methods and class constants to track session state errors
caused by the loss of named locks or temp tables. Such errors can
be resolved by a "session flush" method.
Make assertQueryIsCurrentlyAllowed() better distinguish ROLLBACK
queries from ROLLBACK TO SAVEPOINT queries. For some scenarios,
only full tranasction ROLLBACK queries should be allowed.
Add flushSession() method to Database and flushPrimarySessions()
methods to LBFactory/LoadBalancer.
Also:
* Rename wasKnownStatementRollbackError() and make it take the
error number as an argument, similar to wasConnectionError().
Add mysql error codes for query timeouts since they only cause
statement rollbacks.
* Rename wasConnectionError() and mark it as protected. This is an
internal method with no outside callers.
* Rename wasQueryTimeout(), remove some HHVM-specific code, and
simplify the arguments.
* Make executeQuery() use a for loop for the query retry logic
to reduce code duplication.
* Move the error state setting logic in executeQueryAttempt() up
in order to reduce code duplication.
* Move the beginIfImplied() call in executeQueryAttempt() up to the
retry loop in executeQuery(). This narrows the executeQueryAttempt()
concerns to sending a single query and updating tracking fields.
* Make closeConnection() and doHandleSessionLossPreconnect() in
DatabaseSqlite more consistent with the base class by releasing named locks.
* Mark trxStatus() as @internal.
Bug: T281451
Bug: T293859
Change-Id: I200f90e413b8a725828745f81925b54985c72180
4cac31de4e