-work on DB plugin logic for taler-merchant-exchange

7 files changed, 274 insertions, 4 deletions

diff --git a/src/backend/taler-merchant-exchange.c b/src/backend/taler-merchant-exchange.c
index b440902d..ab4bc03f 100644
--- a/src/backend/taler-merchant-exchange.c
+++ b/src/backend/taler-merchant-exchange.c
@@ -565,8 +565,8 @@ exchange_request (void *cls)
  * @param exchange_url base URL of the exchange that initiated the transfer
  * @param payto_uri account of the merchant that received the transfer
  * @param wtid wire transfer subject identifying the aggregation
- * @param execution_time when did the merchant observe the transfer
  * @param total total amount that was wired
+ * @param next_attempt when should we next try to interact with the exchange
  */
 static void
 start_inquiry (
@@ -576,8 +576,8 @@ start_inquiry (
   const char *exchange_url,
   const char *payto_uri,
   const struct TALER_WireTransferIdentifierRawP *wtid,
-  struct GNUNET_TIME_Absolute execution_time,
-  const struct TALER_Amount *total)
+  const struct TALER_Amount *total,
+  struct GNUNET_TIME_Absolute next_attempt)
 {
   struct Inquiry *w;
 
@@ -587,7 +587,6 @@ start_inquiry (
   w->instance_id = GNUNET_strdup (instance_id);
   w->rowid = rowid;
   w->wtid = *wtid;
-  w->execution_time = execution_time;
   w->total = *total;
   GNUNET_CONTAINER_DLL_insert (w_head,
                                w_tail,
@@ -615,6 +614,7 @@ find_work (void *cls)
   // NOTE: SELECT WHERE confirmed AND NOT verified AND NOT failed?;
   // FIXME: use LIMIT clause! => When do we try again if LIMIT applied?
   qs = db_plugin->select_open_transfers (db_plugin->cls,
+                                         LIMIT - active,
                                          &start_inquiry,
                                          NULL);
   if (qs < 0)
diff --git a/src/backenddb/Makefile.am b/src/backenddb/Makefile.am
index 020b3f7b..c72ddd6f 100644
--- a/src/backenddb/Makefile.am
+++ b/src/backenddb/Makefile.am
@@ -56,6 +56,7 @@ libtaler_plugin_merchantdb_postgres_la_SOURCES = \
   pg_select_wirewatch_accounts.h pg_select_wirewatch_accounts.c \
   pg_insert_account.h pg_insert_account.c \
   pg_update_account.h pg_update_account.c \
+  pg_select_open_transfers.h pg_select_open_transfers.c \
   pg_lookup_instances.h pg_lookup_instances.c \
   pg_lookup_transfers.h pg_lookup_transfers.c \
   plugin_merchantdb_postgres.c  pg_helper.h
diff --git a/src/backenddb/merchant-0005.sql b/src/backenddb/merchant-0005.sql
index 3bb24e66..f90ee701 100644
--- a/src/backenddb/merchant-0005.sql
+++ b/src/backenddb/merchant-0005.sql
@@ -36,6 +36,13 @@ COMMENT ON COLUMN merchant_transfers.failed
 COMMENT ON COLUMN merchant_transfers.validation_status
   IS 'Taler error code describing the state of the validation';
 
+CREATE INDEX merchant_transfers_by_open
+  ON merchant_transfers
+  (ready_time ASC)
+  WHERE confirmed AND NOT (failed OR verified);
+COMMENT ON INDEX merchant_transfers_by_open
+  IS 'For select_open_transfers';
+
 
 ALTER TABLE merchant_accounts
   ADD COLUMN credit_facade_url VARCHAR,
diff --git a/src/backenddb/pg_select_open_transfers.c b/src/backenddb/pg_select_open_transfers.c
new file mode 100644
index 00000000..7113c446
--- /dev/null
+++ b/src/backenddb/pg_select_open_transfers.c
@@ -0,0 +1,167 @@
+/*
+   This file is part of TALER
+   Copyright (C) 2022 Taler Systems SA
+
+   TALER is free software; you can redistribute it and/or modify it under the
+   terms of the GNU General Public License as published by the Free Software
+   Foundation; either version 3, or (at your option) any later version.
+
+   TALER is distributed in the hope that it will be useful, but WITHOUT ANY
+   WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+   A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License along with
+   TALER; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+ */
+/**
+ * @file backenddb/pg_select_open_transfers.c
+ * @brief Implementation of the select_open_transfers function for Postgres
+ * @author Christian Grothoff
+ */
+#include "platform.h"
+#include <taler/taler_error_codes.h>
+#include <taler/taler_dbevents.h>
+#include <taler/taler_pq_lib.h>
+#include "pg_select_open_transfers.h"
+#include "pg_helper.h"
+
+
+/**
+ * Context used for open_transfers_cb().
+ */
+struct SelectOpenTransfersContext
+{
+  /**
+   * Postgres context.
+   */
+  struct PostgresClosure *pg;
+
+  /**
+   * Function to call with the results.
+   */
+  TALER_MERCHANTDB_OpenTransferCallback cb;
+
+  /**
+   * Closure for @a cb.
+   */
+  void *cb_cls;
+
+  /**
+   * Internal result.
+   */
+  enum GNUNET_DB_QueryStatus qs;
+};
+
+
+/**
+ * Function to be called with the results of a SELECT statement
+ * that has returned @a num_results results about tips.
+ *
+ * @param[in,out] cls of type `struct SelectOpenTransfersContext *`
+ * @param result the postgres result
+ * @param num_results the number of results in @a result
+ */
+static void
+open_transfers_cb (void *cls,
+                   PGresult *result,
+                   unsigned int num_results)
+{
+  struct SelectOpenTransfersContext *plc = cls;
+  struct PostgresClosure *pg = plc->pg;
+
+  for (unsigned int i = 0; i < num_results; i++)
+  {
+    uint64_t rowid;
+    char *instance_id;
+    char *exchange_url;
+    char *payto_uri;
+    struct TALER_WireTransferIdentifierRawP wtid;
+    struct TALER_Amount total;
+    struct GNUNET_TIME_Absolute next_attempt;
+    struct GNUNET_PQ_ResultSpec rs[] = {
+      GNUNET_PQ_result_spec_uint64 ("credit_serial",
+                                    &rowid),
+      GNUNET_PQ_result_spec_string ("instance_id",
+                                    &instance_id),
+      GNUNET_PQ_result_spec_string ("exchange_url",
+                                    &exchange_url),
+      GNUNET_PQ_result_spec_string ("payto_uri",
+                                    &payto_uri),
+      GNUNET_PQ_result_spec_auto_from_type ("wtid",
+                                            &wtid),
+      TALER_PQ_RESULT_SPEC_AMOUNT ("credit_amount",
+                                   &total),
+      GNUNET_PQ_result_spec_absolute_time ("next_attempt",
+                                           &next_attempt),
+      GNUNET_PQ_result_spec_end
+    };
+
+    if (GNUNET_OK !=
+        GNUNET_PQ_extract_result (result,
+                                  rs,
+                                  i))
+    {
+      GNUNET_break (0);
+      plc->qs = GNUNET_DB_STATUS_HARD_ERROR;
+      return;
+    }
+    plc->cb (plc->cb_cls,
+             rowid,
+             instance_id,
+             exchange_url,
+             payto_uri,
+             &wtid,
+             &total,
+             next_attempt);
+    GNUNET_PQ_cleanup_result (rs);
+  }
+}
+
+
+enum GNUNET_DB_QueryStatus
+TMH_PG_select_open_transfers (void *cls,
+                              uint64_t limit,
+                              TALER_MERCHANTDB_OpenTransferCallback cb,
+                              void *cb_cls)
+{
+  struct PostgresClosure *pg = cls;
+  struct SelectOpenTransfersContext plc = {
+    .pg = pg,
+    .cb = cb,
+    .cb_cls = cb_cls
+  };
+  struct GNUNET_PQ_QueryParam params[] = {
+    GNUNET_PQ_query_param_uint64 (&limit),
+    GNUNET_PQ_query_param_end
+  };
+  enum GNUNET_DB_QueryStatus qs;
+
+  PREPARE (pg,
+           "select_open_transfers",
+           "SELECT"
+           " credit_serial"
+           ",exchange_url"
+           ",wtid"
+           ",credit_amount_val"
+           ",credit_amount_frac"
+           ",payto_uri"
+           " FROM merchant_transfers"
+           " JOIN merchant_instances"
+           "   USING (merchant_id)"
+           " JOIN merchant_accounts"
+           "   USING (account_serial)"
+           " WHERE confirmed AND"
+           "       NOT (failed OR verified)"
+           " ORDER BY next_attempt INC"
+           " LIMIT $1;");
+
+  qs = GNUNET_PQ_eval_prepared_multi_select (
+    pg->conn,
+    "select_open_transfers",
+    params,
+    &open_transfers_cb,
+    &plc);
+  if (0 != plc.qs)
+    return plc.qs;
+  return qs;
+}
diff --git a/src/backenddb/pg_select_open_transfers.h b/src/backenddb/pg_select_open_transfers.h
new file mode 100644
index 00000000..5857ed80
--- /dev/null
+++ b/src/backenddb/pg_select_open_transfers.h
@@ -0,0 +1,47 @@
+/*
+   This file is part of TALER
+   Copyright (C) 2022 Taler Systems SA
+
+   TALER is free software; you can redistribute it and/or modify it under the
+   terms of the GNU General Public License as published by the Free Software
+   Foundation; either version 3, or (at your option) any later version.
+
+   TALER is distributed in the hope that it will be useful, but WITHOUT ANY
+   WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+   A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License along with
+   TALER; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+ */
+/**
+ * @file backenddb/pg_select_open_transfers.h
+ * @brief implementation of the select_open_transfers function for Postgres
+ * @author Christian Grothoff
+ */
+#ifndef PG_SELECT_OPEN_TRANSFERS_H
+#define PG_SELECT_OPEN_TRANSFERS_H
+
+#include <taler/taler_util.h>
+#include <taler/taler_json_lib.h>
+#include "taler_merchantdb_plugin.h"
+
+
+/**
+ * Retrieve wire transfer details of wire details
+ * that taler-merchant-exchange still needs to
+ * investigate.
+ *
+ * @param cls closure, typically a connection to the db
+ * @param limit maximum number of results to return
+ * @param cb function called with the wire transfer data
+ * @param cb_cls closure for @a cb
+ * @return transaction status
+ */
+enum GNUNET_DB_QueryStatus
+TMH_PG_select_open_transfers (void *cls,
+                              uint64_t limit,
+                              TALER_MERCHANTDB_OpenTransferCallback cb,
+                              void *cb_cls);
+
+
+#endif
diff --git a/src/backenddb/plugin_merchantdb_postgres.c b/src/backenddb/plugin_merchantdb_postgres.c
index e70d8639..6040c9af 100644
--- a/src/backenddb/plugin_merchantdb_postgres.c
+++ b/src/backenddb/plugin_merchantdb_postgres.c
@@ -36,6 +36,7 @@
 #include "pg_lookup_transfers.h"
 #include "pg_update_wirewatch_progress.h"
 #include "pg_select_wirewatch_accounts.h"
+#include "pg_select_open_transfers.h"
 
 
 /**
@@ -9784,6 +9785,8 @@ libtaler_plugin_merchantdb_postgres_init (void *cls)
   plugin->insert_pickup = &postgres_insert_pickup;
   plugin->insert_pickup_blind_signature =
     &postgres_insert_pickup_blind_signature;
+  plugin->select_open_transfers
+    = &TMH_PG_select_open_transfers;
   plugin->lookup_templates = &postgres_lookup_templates;
   plugin->lookup_template = &postgres_lookup_template;
   plugin->delete_template = &postgres_delete_template;
diff --git a/src/include/taler_merchantdb_plugin.h b/src/include/taler_merchantdb_plugin.h
index f0ae6589..62dcf5e7 100644
--- a/src/include/taler_merchantdb_plugin.h
+++ b/src/include/taler_merchantdb_plugin.h
@@ -712,6 +712,32 @@ typedef void
 
 
 /**
+ * Function called with information about wire transfers
+ * that taler-merchant-exchange still needs to process.
+ *
+ * @param cls closure
+ * @param rowid row of the transfer in the merchant database
+ * @param instance_id instance that received the transfer
+ * @param exchange_url base URL of the exchange that initiated the transfer
+ * @param payto_uri account of the merchant that received the transfer
+ * @param wtid wire transfer subject identifying the aggregation
+ * @param execution_time when did the merchant observe the transfer
+ * @param total total amount that was wired
+ * @param next_attempt when should we next try to interact with the exchange
+ */
+typedef void
+(*TALER_MERCHANTDB_OpenTransferCallback)(
+  void *cls,
+  uint64_t rowid,
+  const char *instance_id,
+  const char *exchange_url,
+  const char *payto_uri,
+  const struct TALER_WireTransferIdentifierRawP *wtid,
+  const struct TALER_Amount *total,
+  struct GNUNET_TIME_Absolute next_attempt);
+
+
+/**
  * Function called with detailed information about a wire transfer and
  * the underlying deposits that are being aggregated.
  *
@@ -1927,6 +1953,25 @@ struct TALER_MERCHANTDB_Plugin
 
 
   /**
+   * Retrieve wire transfer details of wire details
+   * that taler-merchant-exchange still needs to
+   * investigate.
+   *
+   * @param cls closure
+   * @param limit maximum number of results to return
+   * @param cb function called with the wire transfer data
+   * @param cb_cls closure for @a cb
+   * @return transaction status
+   */
+  enum GNUNET_DB_QueryStatus
+  (*select_open_transfers)(
+    void *cls,
+    uint64_t limit,
+    TALER_MERCHANTDB_OpenTransferCallback cb,
+    void *cb_cls);
+
+
+  /**
    * Insert wire transfer details for a deposit.
    *
    * @param cls closure