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Base system with REST service to issue digital coins, run by the payment service provider
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iterate_prewires_below_open_shards.c (4458B)

      1 /*
      2    This file is part of TALER
      3    Copyright (C) 2026 Taler Systems SA
      4 
      5    TALER is free software; you can redistribute it and/or modify it under the
      6    terms of the GNU General Public License as published by the Free Software
      7    Foundation; either version 3, or (at your option) any later version.
      8 
      9    TALER is distributed in the hope that it will be useful, but WITHOUT ANY
     10    WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
     11    A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
     12 
     13    You should have received a copy of the GNU General Public License along with
     14    TALER; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
     15  */
     16 /**
     17  * @file exchangedb/iterate_prewires_below_open_shards.c
     18  * @brief Implementation of the iterate_prewires_below_open_shards function for Postgres
     19  * @author Christian Grothoff
     20  */
     21 #include "taler/taler_pq_lib.h"
     22 #include "exchange-database/iterate_prewires_below_open_shards.h"
     23 #include "helper.h"
     24 
     25 /**
     26  * Closure for #prewire_cb().
     27  */
     28 struct PrewireContext
     29 {
     30   /**
     31    * Function to call on each result.
     32    */
     33   TALER_EXCHANGEDB_WirePreparationIterator cb;
     34 
     35   /**
     36    * Closure for @a cb.
     37    */
     38   void *cb_cls;
     39 
     40   /**
     41    * #GNUNET_OK if everything went fine.
     42    */
     43   enum GNUNET_GenericReturnValue status;
     44 };
     45 
     46 
     47 /**
     48  * Invoke the callback for each result.
     49  *
     50  * @param cls a `struct PrewireContext *`
     51  * @param result SQL result
     52  * @param num_results number of rows in @a result
     53  */
     54 static void
     55 prewire_cb (void *cls,
     56             PGresult *result,
     57             unsigned int num_results)
     58 {
     59   struct PrewireContext *pc = cls;
     60 
     61   for (unsigned int i = 0; i < num_results; i++)
     62   {
     63     uint64_t prewire_uuid;
     64     char *wire_method;
     65     void *buf = NULL;
     66     size_t buf_size;
     67     struct GNUNET_PQ_ResultSpec rs[] = {
     68       GNUNET_PQ_result_spec_uint64 ("prewire_uuid",
     69                                     &prewire_uuid),
     70       GNUNET_PQ_result_spec_string ("wire_method",
     71                                     &wire_method),
     72       GNUNET_PQ_result_spec_variable_size ("buf",
     73                                            &buf,
     74                                            &buf_size),
     75       GNUNET_PQ_result_spec_end
     76     };
     77 
     78     if (GNUNET_OK !=
     79         GNUNET_PQ_extract_result (result,
     80                                   rs,
     81                                   i))
     82     {
     83       GNUNET_break (0);
     84       pc->status = GNUNET_SYSERR;
     85       return;
     86     }
     87     pc->cb (pc->cb_cls,
     88             prewire_uuid,
     89             wire_method,
     90             buf,
     91             buf_size);
     92     GNUNET_PQ_cleanup_result (rs);
     93   }
     94 }
     95 
     96 
     97 enum GNUNET_DB_QueryStatus
     98 TALER_EXCHANGEDB_iterate_prewires_below_open_shards (
     99   struct TALER_EXCHANGEDB_PostgresContext *pg,
    100   const char *job_name,
    101   uint64_t limit,
    102   TALER_EXCHANGEDB_WirePreparationIterator cb,
    103   void *cb_cls)
    104 {
    105   struct GNUNET_PQ_QueryParam params[] = {
    106     GNUNET_PQ_query_param_string (job_name),
    107     GNUNET_PQ_query_param_uint64 (&limit),
    108     GNUNET_PQ_query_param_end
    109   };
    110   struct PrewireContext pc = {
    111     .cb = cb,
    112     .cb_cls = cb_cls,
    113     .status = GNUNET_OK
    114   };
    115   enum GNUNET_DB_QueryStatus qs;
    116 
    117   /* The bound is the start of the lowest shard still open, or, with none
    118      open, the end of the highest shard: new shards are only ever opened
    119      above that, so every row below the bound belongs to a completed shard.
    120      No lease covers those rows, hence SKIP LOCKED keeps two workers from
    121      executing the same one. */
    122   PREPARE (pg,
    123            "iterate_prewires_below_open_shards",
    124            "SELECT"
    125            " prewire_uuid"
    126            ",wire_method"
    127            ",buf"
    128            " FROM prewire"
    129            " WHERE prewire_uuid <"
    130            "   COALESCE ("
    131            "     (SELECT MIN(start_row)"
    132            "        FROM work_shards"
    133            "       WHERE job_name=$1"
    134            "         AND completed=FALSE),"
    135            "     (SELECT end_row"
    136            "        FROM work_shards"
    137            "       WHERE job_name=$1"
    138            "       ORDER BY end_row DESC"
    139            "       LIMIT 1),"
    140            "     0)"
    141            "   AND finished=FALSE"
    142            "   AND failed=FALSE"
    143            " ORDER BY prewire_uuid ASC"
    144            " LIMIT $2"
    145            " FOR UPDATE SKIP LOCKED;");
    146   qs = GNUNET_PQ_eval_prepared_multi_select (
    147     pg->conn,
    148     "iterate_prewires_below_open_shards",
    149     params,
    150     &prewire_cb,
    151     &pc);
    152   if (GNUNET_OK != pc.status)
    153     return GNUNET_DB_STATUS_HARD_ERROR;
    154   return qs;
    155 }