From 326110ffe9e1154f18550e12450522ec307a54b6 Mon Sep 17 00:00:00 2001 From: Christian Grothoff Date: Fri, 19 Nov 2021 16:45:55 +0100 Subject: -improve comments, DCE --- src/exchangedb/plugin_exchangedb_postgres.c | 25 +++++++++++++++---------- 1 file changed, 15 insertions(+), 10 deletions(-) diff --git a/src/exchangedb/plugin_exchangedb_postgres.c b/src/exchangedb/plugin_exchangedb_postgres.c index 57c222455..6cceeb444 100644 --- a/src/exchangedb/plugin_exchangedb_postgres.c +++ b/src/exchangedb/plugin_exchangedb_postgres.c @@ -4122,8 +4122,9 @@ notify_on_reserve (struct PostgresClosure *pg, /** - * Insert an incoming transaction into reserves. New reserves are also created - * through this function. + * Insert an incoming transaction into reserves. New reserves are also + * created through this function. Started within the scope of an ongoing + * transaction. * * @param cls the `struct PostgresClosure` with the plugin-specific state * @param reserve_pub public key of the reserve @@ -4170,7 +4171,7 @@ postgres_reserves_in_insert (void *cls, /* Optimistically assume this is a new reserve, create balance for the first time; we do this before adding the actual transaction to "reserves_in", as for a new reserve it can't be a duplicate 'add' operation, and as - the 'add' operation may need the reserve entry as a foreign key. */ + the 'add' operation needs the reserve entry as a foreign key. */ { struct GNUNET_PQ_QueryParam params[] = { GNUNET_PQ_query_param_auto_from_type (reserve_pub), @@ -4217,6 +4218,7 @@ postgres_reserves_in_insert (void *cls, GNUNET_assert (0 != kyc.payment_target_uuid); if (GNUNET_DB_STATUS_SUCCESS_NO_RESULTS == qs1) { + /* We do not have the UUID, so insert by public key */ struct GNUNET_PQ_QueryParam params[] = { GNUNET_PQ_query_param_auto_from_type (&reserve.pub), GNUNET_PQ_query_param_uint64 (&wire_ref), @@ -4233,6 +4235,7 @@ postgres_reserves_in_insert (void *cls, } else { + /* We do have the UUID, use that for the insert */ struct GNUNET_PQ_QueryParam params[] = { GNUNET_PQ_query_param_uint64 (&reserve_uuid), GNUNET_PQ_query_param_uint64 (&wire_ref), @@ -4247,16 +4250,14 @@ postgres_reserves_in_insert (void *cls, "reserves_in_add_by_uuid", params); } - if (GNUNET_DB_STATUS_SUCCESS_ONE_RESULT != qs2) - { - GNUNET_break (GNUNET_DB_STATUS_HARD_ERROR != qs2); - return qs2; - } + /* qs2 could be 0 as both statements used 'ON CONFLICT DO NOTHING' */ if (0 >= qs2) { if ( (GNUNET_DB_STATUS_SUCCESS_NO_RESULTS == qs2) && (GNUNET_DB_STATUS_SUCCESS_NO_RESULTS != qs1) ) { + /* Conflict for the transaction, but the reserve was + just now created, that should be impossible. */ GNUNET_break (0); /* should be impossible: reserve was fresh, but transaction already known */ return GNUNET_DB_STATUS_HARD_ERROR; @@ -4267,14 +4268,18 @@ postgres_reserves_in_insert (void *cls, } if (GNUNET_DB_STATUS_SUCCESS_ONE_RESULT == qs1) { + /* New reserve, we are finished */ notify_on_reserve (pg, reserve_pub); - return GNUNET_DB_STATUS_SUCCESS_ONE_RESULT; /* new reserve, we are finished */ + return GNUNET_DB_STATUS_SUCCESS_ONE_RESULT; } /* we were wrong with our optimistic assumption: - reserve does exist, need to do an update instead */ + reserve did already exist, need to do an update instead */ { + /* We need to move away from 'read committed' to serializable. + Also, we know that it should be safe to commit at this point. + (We are only run in a larger transaction for performance.) */ enum GNUNET_DB_QueryStatus cs; cs = postgres_commit (pg); -- cgit v1.2.3