add 'get_latest_reserve_in_reference' to exchangedb API

src/exchangedb/perf_taler_exchangedb_interpreter.c

@@ -1476,7 +1476,7 @@ interpret (struct PERF_TALER_EXCHANGEDB_interpreter_state *state)
         {
           unsigned int dki_index;
           unsigned int reserve_index;
-          struct PERF_TALER_EXCHANGEDB_Coin *coin ;
+          struct PERF_TALER_EXCHANGEDB_Coin *coin;
 
           dki_index     = state->cmd[state->i].details.create_withdraw.index_dki;
           reserve_index = state->cmd[state->i].details.create_withdraw.index_reserve;
@@ -1491,7 +1491,7 @@ interpret (struct PERF_TALER_EXCHANGEDB_interpreter_state *state)
         {
           unsigned int coin_index;
           int ret;
-          struct PERF_TALER_EXCHANGEDB_Coin *coin ;
+          struct PERF_TALER_EXCHANGEDB_Coin *coin;
 
           coin_index = state->cmd[state->i].details.insert_withdraw.index_coin;
           coin = state->cmd[coin_index].exposed.data.coin;

src/exchangedb/plugin_exchangedb_postgres.c

@@ -769,6 +769,15 @@ postgres_prepare (PGconn *db_conn)
            7, NULL);
 
 
+  /* Used in postgres_select_reserves_in_above_serial_id() to obtain inbound
+     transactions for reserves with serial id '\geq' the given parameter */
+  PREPARE ("reserves_in_get_latest_wire_reference",
+           "SELECT"
+           " wire_reference"
+           " FROM reserves_in"
+           " ORDER BY reserve_in_serial_id DESC LIMIT 1",
+           0, NULL);
+
   /* Used in postgres_select_reserves_in_above_serial_id() to obtain inbound
      transactions for reserves with serial id '\geq' the given parameter */
   PREPARE ("audit_reserves_in_get_transactions_incr",
@@ -2250,6 +2259,66 @@ postgres_reserves_in_insert (void *cls,
 }
 
 
+/**
+ * Obtain the most recent @a wire_reference that was inserted via @e reserves_in_insert.
+ *
+ * @param cls the @e cls of this struct with the plugin-specific state
+ * @param session the database session handle
+ * @param[out] wire_reference set to unique reference identifying the wire transfer (binary blob)
+ * @param[out] wire_reference_size set to number of bytes in @a wire_reference
+ * @return #GNUNET_OK upon success; #GNUNET_NO if we never got any incoming transfers
+ *         #GNUNET_SYSERR upon failures (DB error)
+ */
+static int
+postgres_get_latest_reserve_in_reference (void *cls,
+                                          struct TALER_EXCHANGEDB_Session *session,
+                                          void **wire_reference,
+                                          size_t *wire_reference_size)
+{
+  PGresult *result;
+  struct GNUNET_PQ_QueryParam params[] = {
+    GNUNET_PQ_query_param_end
+  };
+  int ret;
+
+  ret = GNUNET_SYSERR;
+  result = GNUNET_PQ_exec_prepared (session->conn,
+                                    "reserves_in_get_latest_wire_reference",
+                                    params);
+  if (PGRES_TUPLES_OK != PQresultStatus (result))
+  {
+    QUERY_ERR (result, session->conn);
+    goto cleanup;
+  }
+  if (0 == PQntuples (result))
+  {
+    ret = GNUNET_NO;
+    goto cleanup;
+  }
+  {
+    struct GNUNET_PQ_ResultSpec rs[] = {
+      GNUNET_PQ_result_spec_variable_size ("wire_reference",
+                                           wire_reference,
+                                           wire_reference_size),
+      GNUNET_PQ_result_spec_end
+    };
+
+    if (GNUNET_OK !=
+        GNUNET_PQ_extract_result (result,
+                                  rs,
+                                  0))
+    {
+      GNUNET_break (0);
+      goto cleanup;
+    }
+  }
+  ret = GNUNET_OK;
+ cleanup:
+  PQclear (result);
+  return ret;
+}
+
+
 /**
  * Locate the response for a /reserve/withdraw request under the
  * key of the hash of the blinded message.
@@ -6657,6 +6726,7 @@ libtaler_plugin_exchangedb_postgres_init (void *cls)
   plugin->get_denomination_info = &postgres_get_denomination_info;
   plugin->reserve_get = &postgres_reserve_get;
   plugin->reserves_in_insert = &postgres_reserves_in_insert;
+  plugin->get_latest_reserve_in_reference = &postgres_get_latest_reserve_in_reference;
   plugin->get_withdraw_info = &postgres_get_withdraw_info;
   plugin->insert_withdraw_info = &postgres_insert_withdraw_info;
   plugin->get_reserve_history = &postgres_get_reserve_history;

src/exchangedb/test_exchangedb.c

@@ -1445,6 +1445,8 @@ run (void *cls)
 \"r\":123456789,                                     \
 \"address\": \"foobar\"}";
   unsigned int cnt;
+  void *rr;
+  size_t rr_size;
 
   dkp = NULL;
   rh = NULL;
@@ -1503,6 +1505,11 @@ run (void *cls)
   result = 4;
   sndr = json_loads ("{ \"account\":\"1\" }", 0, NULL);
   GNUNET_assert (NULL != sndr);
+  FAILIF (GNUNET_NO !=
+          plugin->get_latest_reserve_in_reference (plugin->cls,
+                                                   session,
+                                                   &rr,
+                                                   &rr_size));
   FAILIF (GNUNET_OK !=
           plugin->reserves_in_insert (plugin->cls,
                                       session,
@@ -1512,6 +1519,14 @@ run (void *cls)
                                       sndr,
                                       "TEST",
                                       4));
+  FAILIF (GNUNET_OK !=
+          plugin->get_latest_reserve_in_reference (plugin->cls,
+                                                   session,
+                                                   &rr,
+                                                   &rr_size));
+  FAILIF (4 != rr_size);
+  FAILIF (0 != memcmp ("TEST", rr, 4));
+  GNUNET_free (rr);
   FAILIF (GNUNET_OK !=
           check_reserve (session,
                          &reserve_pub,
@@ -1527,6 +1542,19 @@ run (void *cls)
 				      sndr,
                                       "TEST2",
                                       5));
+  FAILIF (GNUNET_OK !=
+          plugin->get_latest_reserve_in_reference (plugin->cls,
+                                                   session,
+                                                   &rr,
+                                                   &rr_size));
+  FAILIF (GNUNET_OK !=
+          plugin->get_latest_reserve_in_reference (plugin->cls,
+                                                   session,
+                                                   &rr,
+                                                   &rr_size));
+  FAILIF (5 != rr_size);
+  FAILIF (0 != memcmp ("TEST2", rr, 5));
+  GNUNET_free (rr);
   json_decref (sndr);
   FAILIF (GNUNET_OK !=
           check_reserve (session,

src/include/taler_exchangedb_plugin.h

@@ -1204,6 +1204,23 @@ struct TALER_EXCHANGEDB_Plugin
                          size_t wire_reference_size);
 
 
+  /**
+   * Obtain the most recent @a wire_reference that was inserted via @e reserves_in_insert.
+   *
+   * @param cls the @e cls of this struct with the plugin-specific state
+   * @param db the database connection handle
+   * @param[out] wire_reference set to unique reference identifying the wire transfer (binary blob)
+   * @param[out] wire_reference_size set to number of bytes in @a wire_reference
+   * @return #GNUNET_OK upon success; #GNUNET_NO if we never got any incoming transfers
+   *         #GNUNET_SYSERR upon failures (DB error)
+   */
+  int
+  (*get_latest_reserve_in_reference)(void *cls,
+                                     struct TALER_EXCHANGEDB_Session *db,
+                                     void **wire_reference,
+                                     size_t *wire_reference_size);
+
+
   /**
    * Locate the response for a /withdraw request under the
    * key of the hash of the blinded message.