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/*
This file is part of TALER
Copyright (C) 2014-2018 GNUnet e.V.
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 taler-auditor-httpd_db.c
* @brief Generic database operations for the auditor.
* @author Christian Grothoff
*/
#include "platform.h"
#include <pthread.h>
#include <jansson.h>
#include <gnunet/gnunet_json_lib.h>
#include "taler_json_lib.h"
#include "taler_mhd_lib.h"
#include "taler-auditor-httpd_db.h"
#include "taler-auditor-httpd.h"
/**
* How often should we retry a transaction before giving up
* (for transactions resulting in serialization/dead locks only).
*/
#define MAX_TRANSACTION_COMMIT_RETRIES 100
/**
* Run a database transaction for @a connection.
* Starts a transaction and calls @a cb. Upon success,
* attempts to commit the transaction. Upon soft failures,
* retries @a cb a few times. Upon hard or persistent soft
* errors, generates an error message for @a connection.
*
* @param connection MHD connection to run @a cb for
* @param name name of the transaction (for debugging)
* @param[out] set to MHD response code, if transaction failed
* @param cb callback implementing transaction logic
* @param cb_cls closure for @a cb, must be read-only!
* @return #GNUNET_OK on success, #GNUNET_SYSERR on failure
*/
int
TAH_DB_run_transaction (struct MHD_Connection *connection,
const char *name,
int *mhd_ret,
TAH_DB_TransactionCallback cb,
void *cb_cls)
{
struct TALER_AUDITORDB_Session *session;
if (NULL != mhd_ret)
*mhd_ret = -1; /* invalid value */
if (NULL == (session = TAH_plugin->get_session (TAH_plugin->cls)))
{
GNUNET_break (0);
if (NULL != mhd_ret)
*mhd_ret = TALER_MHD_reply_with_error (connection,
MHD_HTTP_INTERNAL_SERVER_ERROR,
TALER_EC_DB_SETUP_FAILED,
"failed to establish session with database");
return GNUNET_SYSERR;
}
for (unsigned int retries = 0; retries < MAX_TRANSACTION_COMMIT_RETRIES;
retries++)
{
enum GNUNET_DB_QueryStatus qs;
if (GNUNET_OK !=
TAH_plugin->start (TAH_plugin->cls,
session))
{
GNUNET_break (0);
if (NULL != mhd_ret)
*mhd_ret = TALER_MHD_reply_with_error (connection,
MHD_HTTP_INTERNAL_SERVER_ERROR,
TALER_EC_DB_START_FAILED,
"failed to begin transaction");
return GNUNET_SYSERR;
}
qs = cb (cb_cls,
connection,
session,
mhd_ret);
if (0 > qs)
TAH_plugin->rollback (TAH_plugin->cls,
session);
if (GNUNET_DB_STATUS_HARD_ERROR == qs)
return GNUNET_SYSERR;
if (0 <= qs)
qs = TAH_plugin->commit (TAH_plugin->cls,
session);
if (GNUNET_DB_STATUS_HARD_ERROR == qs)
{
if (NULL != mhd_ret)
*mhd_ret = TALER_MHD_reply_with_error (connection,
MHD_HTTP_INTERNAL_SERVER_ERROR,
TALER_EC_DB_COMMIT_FAILED_HARD,
"failed to commit transaction");
return GNUNET_SYSERR;
}
/* make sure callback did not violate invariants! */
GNUNET_assert ( (NULL == mhd_ret) ||
(-1 == *mhd_ret) );
if (0 <= qs)
return GNUNET_OK;
}
TALER_LOG_ERROR ("Transaction `%s' commit failed %u times\n",
name,
MAX_TRANSACTION_COMMIT_RETRIES);
if (NULL != mhd_ret)
*mhd_ret = TALER_MHD_reply_with_error (connection,
MHD_HTTP_INTERNAL_SERVER_ERROR,
TALER_EC_DB_COMMIT_FAILED_ON_RETRY,
"transaction repeatedly failed to serialize");
return GNUNET_SYSERR;
}
/* end of taler-auditor-httpd_db.c */
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