https://github.com/bitcoin/bitcoin/pull/13033/files
9b2704777 [doc] Include txindex changes in the release notes. ed77dd6b3 [test] Simple unit test for TxIndex. 6d772a3d4 [rpc] Public interfaces to GetTransaction block until synced. a03f804f2 [index] Move disk IO logic from GetTransaction to TxIndex::FindTx. e0a3b8003 [validation] Replace tx index code in validation code with TxIndex. 8181db88f [init] Initialize and start TxIndex in init code. f90c3a62f [index] TxIndex method to wait until caught up. 70d510d93 [index] Allow TxIndex sync thread to be interrupted. 94b4f8bbb [index] TxIndex initial sync thread. 34d68bf3a [index] Create new TxIndex class. c88bcec93 [db] Migration for txindex data to new, separate database. 0cb830324 [db] Create separate database for txindex.
After that:
PR15410 fab6b07c16 test: txindex: interrupt threadGroup before calling destructor (MarcoFalke) PR 14071 faf4a9b674 qa: Stop txindex thread before calling destructor (MarcoFalke)