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authorChristian Grothoff <christian@grothoff.org>2021-06-21 11:47:34 +0200
committerChristian Grothoff <christian@grothoff.org>2021-06-21 11:47:34 +0200
commitc9a928fe357a9f2c9e9b679ea18f3b394b492031 (patch)
tree60a0afb29e71f76f54b525644575dbba0d2345e6 /src/exchangedb
parentde41998d55b6b419fded6ec443182d6de9bf3719 (diff)
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make insert transaction more optimistic, may reduce conflicts
Diffstat (limited to 'src/exchangedb')
-rw-r--r--src/exchangedb/plugin_exchangedb_postgres.c128
1 files changed, 79 insertions, 49 deletions
diff --git a/src/exchangedb/plugin_exchangedb_postgres.c b/src/exchangedb/plugin_exchangedb_postgres.c
index 6536bdc3..d06fc6a1 100644
--- a/src/exchangedb/plugin_exchangedb_postgres.c
+++ b/src/exchangedb/plugin_exchangedb_postgres.c
@@ -436,7 +436,8 @@ postgres_get_session (void *cls)
",expiration_date"
",gc_date"
") VALUES "
- "($1, $2, $3, $4, $5, $6);",
+ "($1, $2, $3, $4, $5, $6)"
+ " ON CONFLICT DO NOTHING;",
6),
/* Used in #postgres_insert_reserve_closed() */
GNUNET_PQ_make_prepare ("reserves_close_insert",
@@ -3442,36 +3443,25 @@ postgres_reserves_in_insert (void *cls,
uint64_t wire_ref)
{
struct PostgresClosure *pg = cls;
- enum GNUNET_DB_QueryStatus reserve_exists;
- enum GNUNET_DB_QueryStatus qs;
+ enum GNUNET_DB_QueryStatus qs1;
struct TALER_EXCHANGEDB_Reserve reserve;
struct GNUNET_TIME_Absolute expiry;
reserve.pub = *reserve_pub;
- reserve_exists = postgres_reserves_get (cls,
- session,
- &reserve);
- if (0 > reserve_exists)
- {
- GNUNET_break (GNUNET_DB_STATUS_SOFT_ERROR == reserve_exists);
- return reserve_exists;
- }
+ expiry = GNUNET_TIME_absolute_add (execution_time,
+ pg->idle_reserve_expiration_time);
+ (void) GNUNET_TIME_round_abs (&expiry);
GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
"Creating reserve %s with expiration in %s\n",
TALER_B2S (reserve_pub),
GNUNET_STRINGS_relative_time_to_string (
pg->idle_reserve_expiration_time,
GNUNET_NO));
- expiry = GNUNET_TIME_absolute_add (execution_time,
- pg->idle_reserve_expiration_time);
- (void) GNUNET_TIME_round_abs (&expiry);
- if (GNUNET_DB_STATUS_SUCCESS_NO_RESULTS == reserve_exists)
+ /* 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. */
{
- /* 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. */
struct GNUNET_PQ_QueryParam params[] = {
GNUNET_PQ_query_param_auto_from_type (reserve_pub),
GNUNET_PQ_query_param_string (sender_account_details),
@@ -3483,24 +3473,16 @@ postgres_reserves_in_insert (void *cls,
GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
"Reserve does not exist; creating a new one\n");
- qs = GNUNET_PQ_eval_prepared_non_select (session->conn,
- "reserve_create",
- params);
- if (0 > qs)
- {
- GNUNET_break (GNUNET_DB_STATUS_HARD_ERROR != qs);
- return qs;
- }
- if (GNUNET_DB_STATUS_SUCCESS_NO_RESULTS == qs)
- {
- /* Maybe DB did not detect serializiability error already,
- but clearly there must be one. Still odd. */
- GNUNET_break (0);
- return GNUNET_DB_STATUS_SOFT_ERROR;
- }
+ /* Note: query uses 'on conflict do nothing' */
+ qs1 = GNUNET_PQ_eval_prepared_non_select (session->conn,
+ "reserve_create",
+ params);
+ if (qs1 < 0)
+ return qs1;
}
+
/* Create new incoming transaction, "ON CONFLICT DO NOTHING"
- is used to guard against duplicates. */
+ is again used to guard against duplicates. */
{
struct GNUNET_PQ_QueryParam params[] = {
GNUNET_PQ_query_param_auto_from_type (&reserve.pub),
@@ -3511,26 +3493,59 @@ postgres_reserves_in_insert (void *cls,
TALER_PQ_query_param_absolute_time (&execution_time),
GNUNET_PQ_query_param_end
};
+ enum GNUNET_DB_QueryStatus qs2;
- qs = GNUNET_PQ_eval_prepared_non_select (session->conn,
- "reserves_in_add_transaction",
- params);
- if (GNUNET_DB_STATUS_SUCCESS_ONE_RESULT != qs)
+ qs2 = GNUNET_PQ_eval_prepared_non_select (session->conn,
+ "reserves_in_add_transaction",
+ params);
+ if (GNUNET_DB_STATUS_SUCCESS_ONE_RESULT != qs2)
{
- GNUNET_break (GNUNET_DB_STATUS_HARD_ERROR != qs);
- return qs;
+ GNUNET_break (GNUNET_DB_STATUS_HARD_ERROR != qs2);
+ return qs2;
+ }
+ if (0 >= qs2)
+ {
+ /* Transaction was already known or error. We are finished. */
+ return qs2;
+ }
+ }
+ if (GNUNET_DB_STATUS_SUCCESS_ONE_RESULT == qs1)
+ return GNUNET_DB_STATUS_SUCCESS_ONE_RESULT; /* new reserve, we are finished */
+
+ /* we were wrong with our optimistic assumption:
+ reserve does exist, need to do an update instead */
+ {
+ enum GNUNET_DB_QueryStatus reserve_exists;
+
+ reserve_exists = postgres_reserves_get (cls,
+ session,
+ &reserve);
+ switch (reserve_exists)
+ {
+ case GNUNET_DB_STATUS_HARD_ERROR:
+ GNUNET_break (0);
+ return reserve_exists;
+ case GNUNET_DB_STATUS_SOFT_ERROR:
+ return reserve_exists;
+ case GNUNET_DB_STATUS_SUCCESS_NO_RESULTS:
+ /* First we got a conflict, but then we cannot select? Very strange. */
+ GNUNET_break (0);
+ return GNUNET_DB_STATUS_SOFT_ERROR;
+ case GNUNET_DB_STATUS_SUCCESS_ONE_RESULT:
+ /* continued below */
+ break;
}
}
- if (GNUNET_DB_STATUS_SUCCESS_ONE_RESULT == reserve_exists)
{
+ struct TALER_EXCHANGEDB_Reserve updated_reserve;
+ enum GNUNET_DB_QueryStatus qs3;
+
/* If the reserve already existed, we need to still update the
balance; we do this after checking for duplication, as
otherwise we might have to actually pay the cost to roll this
back for duplicate transactions; like this, we should virtually
never actually have to rollback anything. */
- struct TALER_EXCHANGEDB_Reserve updated_reserve;
-
updated_reserve.pub = reserve.pub;
if (0 >
TALER_amount_add (&updated_reserve.balance,
@@ -3548,11 +3563,26 @@ postgres_reserves_in_insert (void *cls,
updated_reserve.gc = GNUNET_TIME_absolute_max (updated_reserve.expiry,
reserve.gc);
(void) GNUNET_TIME_round_abs (&updated_reserve.gc);
- return reserves_update (cls,
- session,
- &updated_reserve);
+ qs3 = reserves_update (cls,
+ session,
+ &updated_reserve);
+ switch (qs3)
+ {
+ case GNUNET_DB_STATUS_HARD_ERROR:
+ GNUNET_break (0);
+ return qs3;
+ case GNUNET_DB_STATUS_SOFT_ERROR:
+ return qs3;
+ case GNUNET_DB_STATUS_SUCCESS_NO_RESULTS:
+ /* How can the UPDATE not work here? Very strange. */
+ GNUNET_break (0);
+ return GNUNET_DB_STATUS_HARD_ERROR;
+ case GNUNET_DB_STATUS_SUCCESS_ONE_RESULT:
+ /* continued below */
+ break;
+ }
+ return qs3;
}
- return GNUNET_DB_STATUS_SUCCESS_ONE_RESULT;
}