more work on auditordb plugin API

1 files changed, 593 insertions, 1 deletions

diff --git a/src/include/taler_auditordb_plugin.h b/src/include/taler_auditordb_plugin.h
index ec489c62f..558460838 100644
--- a/src/include/taler_auditordb_plugin.h
+++ b/src/include/taler_auditordb_plugin.h
@@ -25,6 +25,7 @@
 #include <jansson.h>
 #include <gnunet/gnunet_util_lib.h>
 #include "taler_auditordb_lib.h"
+#include "taler_signatures.h"
 
 
 /**
@@ -36,6 +37,9 @@ struct TALER_AUDITORDB_Session;
 /**
  * @brief The plugin API, returned from the plugin's "init" function.
  * The argument given to "init" is simply a configuration handle.
+ *
+ * Functions starting with "get_" return one result, functions starting
+ * with "select_" return multiple results via callbacks.
  */
 struct TALER_AUDITORDB_Plugin
 {
@@ -117,7 +121,7 @@ struct TALER_AUDITORDB_Plugin
   (*rollback) (void *cls,
                struct TALER_AUDITORDB_Session *session);
 
-  
+
   /**
    * Function called to perform "garbage collection" on the
    * database, expiring records we no longer require.
@@ -129,6 +133,594 @@ struct TALER_AUDITORDB_Plugin
   int
   (*gc) (void *cls);
 
+
+  /**
+   * Insert information about a denomination key and in particular
+   * the properties (value, fees, expiration times) the coins signed
+   * with this key have.
+   *
+   * @param cls the @e cls of this struct with the plugin-specific state
+   * @param session connection to use
+   * @param issue issuing information with value, fees and other info about the denomination
+   * @return #GNUNET_OK on success; #GNUNET_SYSERR on failure
+   */
+  int
+  (*insert_denomination_info)(void *cls,
+                              struct TALER_AUDITORDB_Session *session,
+                              const struct TALER_DenominationKeyValidityPS *issue);
+
+
+  /**
+   * Get information about denomination keys of a particular exchange.
+   *
+   * @param cls the @e cls of this struct with the plugin-specific state
+   * @param session connection to use
+   * @param master_pub master public key of the exchange
+   * @param cb function to call with the results
+   * @param cb_cls closure for @a cb
+   * @return #GNUNET_OK on success; #GNUNET_SYSERR on failure
+   */
+  int
+  (*select_denomination_info)(void *cls,
+                              struct TALER_AUDITORDB_Session *session,
+                              const struct TALER_MasterPublicKeyP *master_pub,
+                              void *cb, /* FIXME: type! */
+                              void *cb_cls);
+
+
+  /**
+   * Insert information about a reserve.  There must not be an
+   * existing record for the reserve.
+   *
+   * @param cls the @e cls of this struct with the plugin-specific state
+   * @param session connection to use
+   * @param reserve_pub public key of the reserve
+   * @param master_pub master public key of the exchange
+   * @param reserve_balance amount stored in the reserve
+   * @param withdraw_fee_balance amount the exchange gained in withdraw fees
+   *                             due to withdrawals from this reserve
+   * @param expiration_date expiration date of the reserve
+   * @param last_reserve_in_serial_id up to which point did we consider
+   *                 incoming transfers for the above information
+   * @param last_reserve_out_serial_id up to which point did we consider
+   *                 withdrawals for the above information
+   * @return #GNUNET_OK on success; #GNUNET_SYSERR on failure
+   */
+  int
+  (*insert_reserve_info)(void *cls,
+                         struct TALER_AUDITORDB_Session *session,
+                         const struct TALER_ReservePublicKeyP *reserve_pub,
+                         const struct TALER_MasterPublicKeyP *master_pub,
+                         const struct TALER_Amount *reserve_balance,
+                         const struct TALER_Amount *withdraw_fee_balance,
+                         struct GNUNET_TIME_Absolute expiration_date,
+                         uint64_t last_reserve_in_serial_id,
+                         uint64_t last_reserve_out_serial_id);
+
+
+  /**
+   * Update information about a reserve.  Destructively updates an
+   * existing record, which must already exist.
+   *
+   * @param cls the @e cls of this struct with the plugin-specific state
+   * @param session connection to use
+   * @param reserve_pub public key of the reserve
+   * @param master_pub master public key of the exchange
+   * @param reserve_balance amount stored in the reserve
+   * @param withdraw_fee_balance amount the exchange gained in withdraw fees
+   *                             due to withdrawals from this reserve
+   * @param expiration_date expiration date of the reserve
+   * @param last_reserve_in_serial_id up to which point did we consider
+   *                 incoming transfers for the above information
+   * @param last_reserve_out_serial_id up to which point did we consider
+   *                 withdrawals for the above information
+   * @return #GNUNET_OK on success; #GNUNET_SYSERR on failure
+   */
+  int
+  (*update_reserve_info)(void *cls,
+                         struct TALER_AUDITORDB_Session *session,
+                         const struct TALER_ReservePublicKeyP *reserve_pub,
+                         const struct TALER_MasterPublicKeyP *master_pub,
+                         const struct TALER_Amount *reserve_balance,
+                         const struct TALER_Amount *withdraw_fee_balance,
+                         struct GNUNET_TIME_Absolute expiration_date,
+                         uint64_t last_reserve_in_serial_id,
+                         uint64_t last_reserve_out_serial_id);
+
+
+  /**
+   * Get information about a reserve.
+   *
+   * @param cls the @e cls of this struct with the plugin-specific state
+   * @param session connection to use
+   * @param reserve_pub public key of the reserve
+   * @param master_pub master public key of the exchange
+   * @param[out] reserve_balance amount stored in the reserve
+   * @param[out] withdraw_fee_balance amount the exchange gained in withdraw fees
+   *                             due to withdrawals from this reserve
+   * @param[out] expiration_date expiration date of the reserve
+   * @param[out] last_reserve_in_serial_id up to which point did we consider
+   *                 incoming transfers for the above information
+   * @param[out] last_reserve_out_serial_id up to which point did we consider
+   *                 withdrawals for the above information
+   * @return #GNUNET_OK on success; #GNUNET_NO if there is no known
+   *         record about this reserve; #GNUNET_SYSERR on failure
+   */
+  int
+  (*get_reserve_info)(void *cls,
+                      struct TALER_AUDITORDB_Session *session,
+                      const struct TALER_ReservePublicKeyP *reserve_pub,
+                      const struct TALER_MasterPublicKeyP *master_pub,
+                      struct TALER_Amount *reserve_balance,
+                      struct TALER_Amount *withdraw_fee_balance,
+                      struct GNUNET_TIME_Absolute *expiration_date,
+                      uint64_t *last_reserve_in_serial_id,
+                      uint64_t *last_reserve_out_serial_id);
+
+
+
+  /**
+   * Insert information about all reserves.  There must not be an
+   * existing record for the @a master_pub.
+   *
+   * @param cls the @e cls of this struct with the plugin-specific state
+   * @param session connection to use
+   * @param master_pub master public key of the exchange
+   * @param reserve_balance amount stored in the reserve
+   * @param withdraw_fee_balance amount the exchange gained in withdraw fees
+   *                             due to withdrawals from this reserve
+   * @return #GNUNET_OK on success; #GNUNET_SYSERR on failure
+   */
+  int
+  (*insert_reserve_summary)(void *cls,
+                            struct TALER_AUDITORDB_Session *session,
+                            const struct TALER_MasterPublicKeyP *master_pub,
+                            const struct TALER_Amount *reserve_balance,
+                            const struct TALER_Amount *withdraw_fee_balance);
+
+
+  /**
+   * Update information about all reserves.  Destructively updates an
+   * existing record, which must already exist.
+   *
+   * @param cls the @e cls of this struct with the plugin-specific state
+   * @param session connection to use
+   * @param master_pub master public key of the exchange
+   * @param reserve_balance amount stored in the reserve
+   * @param withdraw_fee_balance amount the exchange gained in withdraw fees
+   *                             due to withdrawals from this reserve
+   * @return #GNUNET_OK on success; #GNUNET_SYSERR on failure
+   */
+  int
+  (*update_reserve_summary)(void *cls,
+                            struct TALER_AUDITORDB_Session *session,
+                            const struct TALER_MasterPublicKeyP *master_pub,
+                            const struct TALER_Amount *reserve_balance,
+                            const struct TALER_Amount *withdraw_fee_balance);
+
+
+  /**
+   * Get summary information about all reserves.
+   *
+   * @param cls the @e cls of this struct with the plugin-specific state
+   * @param session connection to use
+   * @param master_pub master public key of the exchange
+   * @param[out] reserve_balance amount stored in the reserve
+   * @param[out] withdraw_fee_balance amount the exchange gained in withdraw fees
+   *                             due to withdrawals from this reserve
+   * @return #GNUNET_OK on success; #GNUNET_NO if there is no known
+   *         record about this exchange; #GNUNET_SYSERR on failure
+   */
+  int
+  (*get_reserve_summary)(void *cls,
+                         struct TALER_AUDITORDB_Session *session,
+                         const struct TALER_MasterPublicKeyP *master_pub,
+                         struct TALER_Amount *reserve_balance,
+                         struct TALER_Amount *withdraw_fee_balance);
+
+
+  /**
+   * Insert information about a denomination key's balances.  There
+   * must not be an existing record for the denomination key.
+   *
+   * @param cls the @e cls of this struct with the plugin-specific state
+   * @param session connection to use
+   * @param denom_pub_hash hash of the denomination public key
+   * @param denom_balance value of coins outstanding with this denomination key
+   * @param deposit_fee_balance total deposit fees collected for this DK
+   * @param melt_fee_balance total melt fees collected for this DK
+   * @param refund_fee_balance total refund fees collected for this DK
+   * @param last_reserve_out_serial_id up to which point did we consider
+   *                 withdrawals for the above information
+   * @param last_deposit_serial_id up to which point did we consider
+   *                 deposits for the above information
+   * @param last_melt_serial_id up to which point did we consider
+   *                 melts for the above information
+   * @param last_refund_serial_id up to which point did we consider
+   *                 refunds for the above information
+   * @return #GNUNET_OK on success; #GNUNET_SYSERR on failure
+   */
+  int
+  (*insert_denomination_balance)(void *cls,
+                                 struct TALER_AUDITORDB_Session *session,
+                                 const struct GNUNET_HashCode *denom_pub_hash,
+                                 const struct TALER_Amount *denom_balance,
+                                 const struct TALER_Amount *deposit_fee_balance,
+                                 const struct TALER_Amount *melt_fee_balance,
+                                 const struct TALER_Amount *refund_fee_balance,
+                                 uint64_t last_reserve_out_serial_id,
+                                 uint64_t last_deposit_serial_id,
+                                 uint64_t last_melt_serial_id,
+                                 uint64_t last_refund_serial_id);
+
+
+  /**
+   * Update information about a denomination key's balances.  There
+   * must be an existing record for the denomination key.
+   *
+   * @param cls the @e cls of this struct with the plugin-specific state
+   * @param session connection to use
+   * @param denom_pub_hash hash of the denomination public key
+   * @param denom_balance value of coins outstanding with this denomination key
+   * @param deposit_fee_balance total deposit fees collected for this DK
+   * @param melt_fee_balance total melt fees collected for this DK
+   * @param refund_fee_balance total refund fees collected for this DK
+   * @param last_reserve_out_serial_id up to which point did we consider
+   *                 withdrawals for the above information
+   * @param last_deposit_serial_id up to which point did we consider
+   *                 deposits for the above information
+   * @param last_melt_serial_id up to which point did we consider
+   *                 melts for the above information
+   * @param last_refund_serial_id up to which point did we consider
+   *                 refunds for the above information
+   * @return #GNUNET_OK on success; #GNUNET_SYSERR on failure
+   */
+  int
+  (*update_denomination_balance)(void *cls,
+                                 struct TALER_AUDITORDB_Session *session,
+                                 const struct GNUNET_HashCode *denom_pub_hash,
+                                 const struct TALER_Amount *denom_balance,
+                                 const struct TALER_Amount *deposit_fee_balance,
+                                 const struct TALER_Amount *melt_fee_balance,
+                                 const struct TALER_Amount *refund_fee_balance,
+                                 uint64_t last_reserve_out_serial_id,
+                                 uint64_t last_deposit_serial_id,
+                                 uint64_t last_melt_serial_id,
+                                 uint64_t last_refund_serial_id);
+
+
+  /**
+   * Get information about a denomination key's balances.
+   *
+   * @param cls the @e cls of this struct with the plugin-specific state
+   * @param session connection to use
+   * @param denom_pub_hash hash of the denomination public key
+   * @param[out] denom_balance value of coins outstanding with this denomination key
+   * @param[out] deposit_fee_balance total deposit fees collected for this DK
+   * @param[out] melt_fee_balance total melt fees collected for this DK
+   * @param[out] refund_fee_balance total refund fees collected for this DK
+   * @param[out] last_reserve_out_serial_id up to which point did we consider
+   *                 withdrawals for the above information
+   * @param[out] last_deposit_serial_id up to which point did we consider
+   *                 deposits for the above information
+   * @param[out] last_melt_serial_id up to which point did we consider
+   *                 melts for the above information
+   * @param[out] last_refund_serial_id up to which point did we consider
+   *                 refunds for the above information
+   * @return #GNUNET_OK on success; #GNUNET_SYSERR on failure
+   */
+  int
+  (*get_denomination_balance)(void *cls,
+                              struct TALER_AUDITORDB_Session *session,
+                              const struct GNUNET_HashCode *denom_pub_hash,
+                              struct TALER_Amount *denom_balance,
+                              struct TALER_Amount *deposit_fee_balance,
+                              struct TALER_Amount *melt_fee_balance,
+                              struct TALER_Amount *refund_fee_balance,
+                              uint64_t *last_reserve_out_serial_id,
+                              uint64_t *last_deposit_serial_id,
+                              uint64_t *last_melt_serial_id,
+                              uint64_t *last_refund_serial_id);
+
+
+  /**
+   * Insert information about an exchange's denomination balances.  There
+   * must not be an existing record for the exchange.
+   *
+   * @param cls the @e cls of this struct with the plugin-specific state
+   * @param session connection to use
+   * @param master_pub master key of the exchange
+   * @param denom_balance value of coins outstanding with this denomination key
+   * @param deposit_fee_balance total deposit fees collected for this DK
+   * @param melt_fee_balance total melt fees collected for this DK
+   * @param refund_fee_balance total refund fees collected for this DK
+   * @return #GNUNET_OK on success; #GNUNET_SYSERR on failure
+   */
+  int
+  (*insert_denomination_summary)(void *cls,
+                                 struct TALER_AUDITORDB_Session *session,
+                                 const struct TALER_MasterPublicKeyP *master_pub,
+                                 const struct TALER_Amount *denom_balance,
+                                 const struct TALER_Amount *deposit_fee_balance,
+                                 const struct TALER_Amount *melt_fee_balance,
+                                 const struct TALER_Amount *refund_fee_balance);
+
+
+  /**
+   * Update information about an exchange's denomination balances.  There
+   * must be an existing record for the exchange.
+   *
+   * @param cls the @e cls of this struct with the plugin-specific state
+   * @param session connection to use
+   * @param master_pub master key of the exchange
+   * @param denom_balance value of coins outstanding with this denomination key
+   * @param deposit_fee_balance total deposit fees collected for this DK
+   * @param melt_fee_balance total melt fees collected for this DK
+   * @param refund_fee_balance total refund fees collected for this DK
+   * @return #GNUNET_OK on success; #GNUNET_SYSERR on failure
+   */
+  int
+  (*update_denomination_summary)(void *cls,
+                                 struct TALER_AUDITORDB_Session *session,
+                                 const struct TALER_MasterPublicKeyP *master_pub,
+                                 const struct TALER_Amount *denom_balance,
+                                 const struct TALER_Amount *deposit_fee_balance,
+                                 const struct TALER_Amount *melt_fee_balance,
+                                 const struct TALER_Amount *refund_fee_balance);
+
+
+  /**
+   * Get information about an exchange's denomination balances.
+   *
+   * @param cls the @e cls of this struct with the plugin-specific state
+   * @param session connection to use
+   * @param master_pub master key of the exchange
+   * @param[out] denom_balance value of coins outstanding with this denomination key
+   * @param[out] deposit_fee_balance total deposit fees collected for this DK
+   * @param[out] melt_fee_balance total melt fees collected for this DK
+   * @param[out] refund_fee_balance total refund fees collected for this DK
+   * @return #GNUNET_OK on success; #GNUNET_NO if there is no entry
+   *           for this @a master_pub; #GNUNET_SYSERR on failure
+   */
+  int
+  (*get_denomination_summary)(void *cls,
+                              struct TALER_AUDITORDB_Session *session,
+                              const struct TALER_MasterPublicKeyP *master_pub,
+                              struct TALER_Amount *denom_balance,
+                              struct TALER_Amount *deposit_fee_balance,
+                              struct TALER_Amount *melt_fee_balance,
+                              struct TALER_Amount *refund_fee_balance);
+
+
+  /**
+   * Insert information about an exchange's risk exposure.  There
+   * must not be an existing record for the exchange.
+   *
+   * @param cls the @e cls of this struct with the plugin-specific state
+   * @param session connection to use
+   * @param master_pub master key of the exchange
+   * @param risk maximum risk exposure of the exchange
+   * @return #GNUNET_OK on success; #GNUNET_SYSERR on failure
+   */
+  int
+  (*insert_risk_summary)(void *cls,
+                         struct TALER_AUDITORDB_Session *session,
+                         const struct TALER_MasterPublicKeyP *master_pub,
+                         const struct TALER_Amount *risk);
+
+
+  /**
+   * Update information about an exchange's risk exposure.  There
+   * must be an existing record for the exchange.
+   *
+   * @param cls the @e cls of this struct with the plugin-specific state
+   * @param session connection to use
+   * @param master_pub master key of the exchange
+   * @param risk maximum risk exposure of the exchange
+   * @return #GNUNET_OK on success; #GNUNET_SYSERR on failure
+   */
+  int
+  (*update_risk_summary)(void *cls,
+                         struct TALER_AUDITORDB_Session *session,
+                         const struct TALER_MasterPublicKeyP *master_pub,
+                         const struct TALER_Amount *risk);
+
+
+  /**
+   * Get information about an exchange's risk exposure.
+   *
+   * @param cls the @e cls of this struct with the plugin-specific state
+   * @param session connection to use
+   * @param master_pub master key of the exchange
+   * @param[out] risk maximum risk exposure of the exchange
+   * @return #GNUNET_OK on success; #GNUNET_SYSERR on failure;
+   *         #GNUNET_NO if we have no records for the @a master_pub
+   */
+  int
+  (*get_risk_summary)(void *cls,
+                      struct TALER_AUDITORDB_Session *session,
+                      const struct TALER_MasterPublicKeyP *master_pub,
+                      struct TALER_Amount *risk);
+
+
+  /**
+   * Insert information about an exchange's historic
+   * revenue about a denomination key.
+   *
+   * @param cls the @e cls of this struct with the plugin-specific state
+   * @param session connection to use
+   * @param master_pub master key of the exchange
+   * @param denom_pub_hash hash of the denomination key
+   * @param revenue_timestamp when did this profit get realized
+   * @param revenue_balance what was the total profit made from
+   *                        deposit fees, melting fees, refresh fees
+   *                        and coins that were never returned?
+   * @param deposit_fee_balance total profits from deposit fees
+   * @param melt_fee_balance total profits from melting fees
+   * @param refund_fee_balance total profits from refund fees
+   * @return #GNUNET_OK on success; #GNUNET_SYSERR on failure
+   */
+  int
+  (*insert_historic_denom_revenue)(void *cls,
+                                   struct TALER_AUDITORDB_Session *session,
+                                   const struct TALER_MasterPublicKeyP *master_pub,
+                                   const struct GNUNET_HashCode *denom_pub_hash,
+                                   struct GNUNET_TIME_Absolute revenue_timestamp,
+                                   const struct TALER_Amount *revenue_balance,
+                                   const struct TALER_Amount *deposit_fee_balance,
+                                   const struct TALER_Amount *melt_fee_balance,
+                                   const struct TALER_Amount *refund_fee_balance);
+
+  /**
+   * Obtain all of the historic denomination key revenue
+   * of the given @a master_pub.
+   *
+   * @param cls the @e cls of this struct with the plugin-specific state
+   * @param session connection to use
+   * @param master_pub master key of the exchange
+   * @param cb function to call with the results
+   * @param cb_cls closure for @a cb
+   * @return #GNUNET_OK on success, #GNUNET_SYSERR on failure
+   */
+  int
+  (*select_historic_denom_revnue)(void *cls,
+                                  struct TALER_AUDITORDB_Session *session,
+                                  const struct TALER_MasterPublicKeyP *master_pub,
+                                  void *cb, /* FIXME: fix type */
+                                  void *cb_cls);
+
+
+  /**
+   * Insert information about an exchange's historic
+   * losses (from compromised denomination keys).
+   *
+   * Note yet used, need to implement exchange's bankrupcy
+   * protocol (and tables!) first.
+   *
+   * @param cls the @e cls of this struct with the plugin-specific state
+   * @param session connection to use
+   * @param master_pub master key of the exchange
+   * @param denom_pub_hash hash of the denomination key
+   * @param loss_timestamp when did this profit get realized
+   * @param loss_balance what was the total loss
+   * @return #GNUNET_OK on success; #GNUNET_SYSERR on failure
+   */
+  int
+  (*insert_historic_losses)(void *cls,
+                            struct TALER_AUDITORDB_Session *session,
+                            const struct TALER_MasterPublicKeyP *master_pub,
+                            const struct GNUNET_HashCode *denom_pub_hash,
+                            struct GNUNET_TIME_Absolute loss_timestamp,
+                            const struct TALER_Amount *loss_balance);
+
+  /**
+   * Obtain all of the historic denomination key losses
+   * of the given @a master_pub.
+   *
+   * @param cls the @e cls of this struct with the plugin-specific state
+   * @param session connection to use
+   * @param master_pub master key of the exchange
+   * @param cb function to call with the results
+   * @param cb_cls closure for @a cb
+   * @return #GNUNET_OK on success, #GNUNET_SYSERR on failure
+   */
+  int
+  (*select_historic_losses)(void *cls,
+                            struct TALER_AUDITORDB_Session *session,
+                            const struct TALER_MasterPublicKeyP *master_pub,
+                            void *cb, /* FIXME: fix type */
+                            void *cb_cls);
+
+
+  /**
+   * Insert information about an exchange's historic revenue from reserves.
+   *
+   * @param cls the @e cls of this struct with the plugin-specific state
+   * @param session connection to use
+   * @param master_pub master key of the exchange
+   * @param start_time beginning of aggregated time interval
+   * @param end_time end of aggregated time interval
+   * @param reserve_profits total profits made
+   * @return #GNUNET_OK on success; #GNUNET_SYSERR on failure
+   */
+  int
+  (*insert_historic_reserve_revenue)(void *cls,
+                                     struct TALER_AUDITORDB_Session *session,
+                                     const struct TALER_MasterPublicKeyP *master_pub,
+                                     struct GNUNET_TIME_Absolute start_time,
+                                     struct GNUNET_TIME_Absolute end_time,
+                                     const struct TALER_Amount *reserve_profits);
+
+
+  /**
+   * Return information about an exchange's historic revenue from reserves.
+   *
+   * @param cls the @e cls of this struct with the plugin-specific state
+   * @param session connection to use
+   * @param master_pub master key of the exchange
+   * @param cb function to call with results
+   * @param cb_cls closure for @a cb
+   * @return #GNUNET_OK on success; #GNUNET_SYSERR on failure
+   */
+  int
+  (*select_historic_reserve_revenue)(void *cls,
+                                     struct TALER_AUDITORDB_Session *session,
+                                     const struct TALER_MasterPublicKeyP *master_pub,
+                                     void *cb, /* FIXME: type */
+                                     void *cb_cls);
+
+
+
+  /**
+   * Insert information about the predicted exchange's bank
+   * account balance.
+   *
+   * @param cls the @e cls of this struct with the plugin-specific state
+   * @param session connection to use
+   * @param master_pub master key of the exchange
+   * @param balance what the bank account balance of the exchange should show
+   * @return #GNUNET_OK on success; #GNUNET_SYSERR on failure
+   */
+  int
+  (*insert_predicted_result)(void *cls,
+                             struct TALER_AUDITORDB_Session *session,
+                             const struct TALER_MasterPublicKeyP *master_pub,
+                             const struct TALER_Amount *balance);
+
+
+  /**
+   * Update information about an exchange's predicted balance.  There
+   * must be an existing record for the exchange.
+   *
+   * @param cls the @e cls of this struct with the plugin-specific state
+   * @param session connection to use
+   * @param master_pub master key of the exchange
+   * @param balance what the bank account balance of the exchange should show
+   * @return #GNUNET_OK on success; #GNUNET_SYSERR on failure
+   */
+  int
+  (*update_predicted_result)(void *cls,
+                             struct TALER_AUDITORDB_Session *session,
+                             const struct TALER_MasterPublicKeyP *master_pub,
+                             const struct TALER_Amount *balance);
+
+
+  /**
+   * Get an exchange's predicted balance.
+   *
+   * @param cls the @e cls of this struct with the plugin-specific state
+   * @param session connection to use
+   * @param master_pub master key of the exchange
+   * @param[out] balance expected bank account balance of the exchange
+   * @return #GNUNET_OK on success; #GNUNET_SYSERR on failure;
+   *         #GNUNET_NO if we have no records for the @a master_pub
+   */
+  int
+  (*get_predicted_balance)(void *cls,
+                           struct TALER_AUDITORDB_Session *session,
+                           const struct TALER_MasterPublicKeyP *master_pub,
+                           struct TALER_Amount *balance);
+
 };