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save 2ms on deposit by not doing idempotency check twice

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Christian Grothoff 2021-12-04 23:24:44 +01:00
parent ec45eaae18
commit e61a53806e
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GPG Key ID: 939E6BE1E29FC3CC
1 changed files with 19 additions and 67 deletions
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86
src/exchange/taler-exchange-httpd_deposit.c
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@ -139,11 +139,12 @@ struct DepositContext
/** /**
* Check if /deposit is already in the database. IF it returns a non-error * Execute database transaction for /deposit. Runs the transaction
* code, the transaction logic MUST NOT queue a MHD response. IF it returns * logic; IF it returns a non-error code, the transaction logic MUST
* an hard error, the transaction logic MUST queue a MHD response and set @a * NOT queue a MHD response. IF it returns an hard error, the
* mhd_ret. We do return a "hard" error also if we found the deposit in the * transaction logic MUST queue a MHD response and set @a mhd_ret. IF
* database and generated a regular response. * it returns the soft error code, the function MAY be called again to
* retry and MUST not queue a MHD response.
* *
* @param cls a `struct DepositContext` * @param cls a `struct DepositContext`
* @param connection MHD request context * @param connection MHD request context
@ -151,15 +152,24 @@ struct DepositContext
* @return transaction status * @return transaction status
*/ */
static enum GNUNET_DB_QueryStatus static enum GNUNET_DB_QueryStatus
deposit_precheck (void *cls, deposit_transaction (void *cls,
struct MHD_Connection *connection, struct MHD_Connection *connection,
MHD_RESULT *mhd_ret) MHD_RESULT *mhd_ret)
{ {
struct DepositContext *dc = cls; struct DepositContext *dc = cls;
const struct TALER_EXCHANGEDB_Deposit *deposit = dc->deposit; const struct TALER_EXCHANGEDB_Deposit *deposit = dc->deposit;
struct TALER_Amount deposit_fee; struct TALER_Amount spent;
enum GNUNET_DB_QueryStatus qs; enum GNUNET_DB_QueryStatus qs;
struct TALER_Amount deposit_fee;
/* make sure coin is 'known' in database */
qs = TEH_make_coin_known (&deposit->coin,
connection,
mhd_ret);
if (qs < 0)
return qs;
/* Check for idempotency: did we get this request before? */
qs = TEH_plugin->have_deposit (TEH_plugin->cls, qs = TEH_plugin->have_deposit (TEH_plugin->cls,
deposit, deposit,
&deposit_fee, &deposit_fee,
@ -196,51 +206,8 @@ deposit_precheck (void *cls,
deposit->wire_deadline, deposit->wire_deadline,
&deposit->merchant_pub, &deposit->merchant_pub,
&amount_without_fee); &amount_without_fee);
/* Treat as 'hard' DB error as we want to rollback and
never try again. */
return GNUNET_DB_STATUS_HARD_ERROR; return GNUNET_DB_STATUS_HARD_ERROR;
} }
return GNUNET_DB_STATUS_SUCCESS_NO_RESULTS;
}
/**
* Execute database transaction for /deposit. Runs the transaction
* logic; IF it returns a non-error code, the transaction logic MUST
* NOT queue a MHD response. IF it returns an hard error, the
* transaction logic MUST queue a MHD response and set @a mhd_ret. IF
* it returns the soft error code, the function MAY be called again to
* retry and MUST not queue a MHD response.
*
* @param cls a `struct DepositContext`
* @param connection MHD request context
* @param[out] mhd_ret set to MHD status on error
* @return transaction status
*/
static enum GNUNET_DB_QueryStatus
deposit_transaction (void *cls,
struct MHD_Connection *connection,
MHD_RESULT *mhd_ret)
{
struct DepositContext *dc = cls;
const struct TALER_EXCHANGEDB_Deposit *deposit = dc->deposit;
struct TALER_Amount spent;
enum GNUNET_DB_QueryStatus qs;
/* make sure coin is 'known' in database */
qs = TEH_make_coin_known (&deposit->coin,
connection,
mhd_ret);
if (qs < 0)
return qs;
/* Theoretically, someone other threat may have received
and committed the deposit in the meantime. Check now
that we are in the transaction scope. */
qs = deposit_precheck (cls,
connection,
mhd_ret);
if (qs < 0)
return qs;
/* Start with fee for THIS transaction */ /* Start with fee for THIS transaction */
spent = deposit->amount_with_fee; spent = deposit->amount_with_fee;
@ -412,22 +379,7 @@ TEH_handler_deposit (struct MHD_Connection *connection,
TALER_merchant_wire_signature_hash (dc.payto_uri, TALER_merchant_wire_signature_hash (dc.payto_uri,
&deposit.wire_salt, &deposit.wire_salt,
&dc.h_wire); &dc.h_wire);
/* Check for idempotency: did we get this request before? */
dc.deposit = &deposit; dc.deposit = &deposit;
{
MHD_RESULT mhd_ret;
if (GNUNET_OK !=
TEH_DB_run_transaction (connection,
"precheck deposit",
&mhd_ret,
&deposit_precheck,
&dc))
{
GNUNET_JSON_parse_free (spec);
return mhd_ret;
}
}
/* new deposit */ /* new deposit */
dc.exchange_timestamp = GNUNET_TIME_absolute_get (); dc.exchange_timestamp = GNUNET_TIME_absolute_get ();