diff options
Diffstat (limited to 'src/backend/taler-merchant-httpd_exchanges.c')
| -rw-r--r-- | src/backend/taler-merchant-httpd_exchanges.c | 120 |
1 files changed, 60 insertions, 60 deletions
diff --git a/src/backend/taler-merchant-httpd_exchanges.c b/src/backend/taler-merchant-httpd_exchanges.c index 9a292365..d980ef09 100644 --- a/src/backend/taler-merchant-httpd_exchanges.c +++ b/src/backend/taler-merchant-httpd_exchanges.c @@ -24,10 +24,26 @@ #include "taler-merchant-httpd_exchanges.h" + +/** + * Delay after which we'll re-fetch key information from the exchange. + */ +#define RELOAD_DELAY GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_MINUTES, 2) + +/** + * Threshold after which exponential backoff should not increase. + */ +#define RETRY_BACKOFF_THRESHOLD GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_SECONDS, 60) + + /** - * How often do we retry fetching /keys? + * Perform our exponential back-off calculation, starting at 1 ms + * and then going by a factor of 2 up unto a maximum of RETRY_BACKOFF_THRESHOLD. + * + * @param r current backoff time, initially zero */ -#define KEYS_RETRY_FREQ GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_SECONDS, 10) +#define RETRY_BACKOFF(r) GNUNET_TIME_relative_min (RETRY_BACKOFF_THRESHOLD, \ + GNUNET_TIME_relative_multiply (GNUNET_TIME_relative_max (GNUNET_TIME_UNIT_MILLISECONDS, (r)), 2)); /** @@ -68,7 +84,8 @@ struct TMH_EXCHANGES_FindOperation struct Exchange *my_exchange; /** - * Task scheduled to asynchrnously return the result. + * Task scheduled to asynchronously return the result to + * the find continuation. */ struct GNUNET_SCHEDULER_Task *at; @@ -118,18 +135,23 @@ struct Exchange struct TALER_MasterPublicKeyP master_pub; /** - * At what time should we try to fetch /keys again? + * How long should we wait between the next retry? */ - struct GNUNET_TIME_Absolute retry_time; + struct GNUNET_TIME_Relative retry_delay; /** * Task where we retry fetching /keys from the exchange. + * + * Can also be active when pending=GNUNET_NO, + * since we periodically (every hour) reload the + * exchange keys. */ struct GNUNET_SCHEDULER_Task *retry_task; /** - * Flag which indicates whether some HTTP transfer between - * this merchant and the exchange is still ongoing + * GNUNET_YES to indicate that there is an ongoing + * transfer we're waiting for, + * GNUNET_NO to indicate that key data is up-to-date. */ int pending; @@ -201,12 +223,14 @@ retry_exchange (void *cls) { struct Exchange *exchange = cls; + /* might be a scheduled reload and not our first attempt */ + exchange->pending = GNUNET_YES; exchange->retry_task = NULL; + GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "Connecting to exchange exchange %s in retry_exchange\n", exchange->uri); - exchange->pending = GNUNET_SYSERR; /* failed hard */ exchange->conn = TALER_EXCHANGE_connect (merchant_curl_ctx, exchange->uri, &keys_mgmt_cb, @@ -237,38 +261,36 @@ keys_mgmt_cb (void *cls, struct Exchange *exchange = cls; struct TMH_EXCHANGES_FindOperation *fo; - if (NULL != keys) - { - exchange->pending = GNUNET_NO; - } - else + GNUNET_assert (GNUNET_YES == exchange->pending); + + if (NULL == keys) { + exchange->retry_delay = RETRY_BACKOFF (exchange->retry_delay); GNUNET_log (GNUNET_ERROR_TYPE_WARNING, - "Failed to fetch /keys from `%s'\n", - exchange->uri); + "Failed to fetch /keys from `%s', retrying in %s\n", + exchange->uri, + GNUNET_STRINGS_relative_time_to_string (exchange->retry_delay, GNUNET_YES)); TALER_EXCHANGE_disconnect (exchange->conn); exchange->conn = NULL; - exchange->retry_time = GNUNET_TIME_relative_to_absolute (KEYS_RETRY_FREQ); - /* Always retry trusted exchanges in the background, so that we don't have - * to wait for a customer to trigger it and thus delay his response */ - if (GNUNET_YES == exchange->trusted) - { - exchange->retry_task = GNUNET_SCHEDULER_add_delayed (KEYS_RETRY_FREQ, - &retry_exchange, - exchange); - } - else - { - exchange->pending = GNUNET_SYSERR; /* failed hard */ - } + exchange->retry_task = GNUNET_SCHEDULER_add_delayed (exchange->retry_delay, + &retry_exchange, + exchange); + return; } + + exchange->pending = GNUNET_NO; + /* Schedule for our regular reload. */ + /* FIXME: we might want to take HTTP cache control into account */ + exchange->retry_task = GNUNET_SCHEDULER_add_delayed (RELOAD_DELAY, + &retry_exchange, + exchange); while (NULL != (fo = exchange->fo_head)) { GNUNET_CONTAINER_DLL_remove (exchange->fo_head, exchange->fo_tail, fo); fo->fc (fo->fc_cls, - (NULL != keys) ? exchange->conn : NULL, + exchange->conn, exchange->trusted); GNUNET_free (fo); } @@ -312,7 +334,7 @@ return_result (void *cls) */ struct TMH_EXCHANGES_FindOperation * TMH_EXCHANGES_find_exchange (const char *chosen_exchange, - TMH_EXCHANGES_FindContinuation fc, // process payment + TMH_EXCHANGES_FindContinuation fc, void *fc_cls) { struct Exchange *exchange; @@ -359,29 +381,6 @@ TMH_EXCHANGES_find_exchange (const char *chosen_exchange, chosen_exchange); } - if (GNUNET_SYSERR == exchange->pending) - { - GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, - "Maybe retrying previously contacted exchange `%s'\n", - chosen_exchange); - /* check if we should resume this exchange */ - if (0 == GNUNET_TIME_absolute_get_remaining (exchange->retry_time).rel_value_us) - { - - GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, - "Retrying exchange `%s'\n", - chosen_exchange); - exchange->pending = GNUNET_YES; - } - else - { - GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, - "Not retrying exchange `%s', too early\n", - chosen_exchange); - } - } - - fo = GNUNET_new (struct TMH_EXCHANGES_FindOperation); fo->fc = fc; fo->fc_cls = fc_cls; @@ -434,13 +433,14 @@ TMH_EXCHANGES_find_exchange_cancel (struct TMH_EXCHANGES_FindOperation *fo) /** * Function called on each configuration section. Finds sections - * about exchanges and parses the entries. + * about exchanges, parses the entries and tries to connect to + * it in order to fetch /keys. * * @param cls closure, with a `const struct GNUNET_CONFIGURATION_Handle *` * @param section name of the section */ static void -parse_exchanges (void *cls, +accept_exchanges (void *cls, const char *section) { const struct GNUNET_CONFIGURATION_Handle *cfg = cls; @@ -524,19 +524,19 @@ TMH_EXCHANGES_init (const struct GNUNET_CONFIGURATION_Handle *cfg) return GNUNET_SYSERR; } merchant_curl_rc = GNUNET_CURL_gnunet_rc_create (merchant_curl_ctx); + /* get exchanges from the merchant configuration and try to connect to them */ GNUNET_CONFIGURATION_iterate_sections (cfg, - &parse_exchanges, + &accept_exchanges, (void *) cfg); - /* build JSON with list of trusted exchanges */ + /* build JSON with list of trusted exchanges (will be included in contracts) */ trusted_exchanges = json_array (); for (exchange = exchange_head; NULL != exchange; exchange = exchange->next) { if (GNUNET_YES != exchange->trusted) continue; j_exchange = json_pack ("{s:s, s:o}", - "url", exchange->uri, - "master_pub", GNUNET_JSON_from_data (&exchange->master_pub, - sizeof (struct TALER_MasterPublicKeyP))); + "url", exchange->uri, + "master_pub", GNUNET_JSON_from_data_auto (&exchange->master_pub)); json_array_append_new (trusted_exchanges, j_exchange); } |