res_odbc.c

Go to the documentation of this file.

/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 1999 - 2012, Digium, Inc.
 *
 * Mark Spencer <markster@digium.com>
 *
 * res_odbc.c <ODBC resource manager>
 * Copyright (C) 2004 - 2005 Anthony Minessale II <anthmct@yahoo.com>
 *
 * See http://www.asterisk.org for more information about
 * the Asterisk project. Please do not directly contact
 * any of the maintainers of this project for assistance;
 * the project provides a web site, mailing lists and IRC
 * channels for your use.
 *
 * This program is free software, distributed under the terms of
 * the GNU General Public License Version 2. See the LICENSE file
 * at the top of the source tree.
 */

/*! \file
 *
 * \brief ODBC resource manager
 * 
 * \author Mark Spencer <markster@digium.com>
 * \author Anthony Minessale II <anthmct@yahoo.com>
 * \author Tilghman Lesher <tilghman@digium.com>
 *
 * \arg See also: \ref cdr_odbc
 */

/*** MODULEINFO
   <depend>generic_odbc</depend>
   <depend>ltdl</depend>
   <support_level>core</support_level>
 ***/

#include "asterisk.h"

ASTERISK_FILE_VERSION(__FILE__, "$Revision: 411408 $")

#include "asterisk/file.h"
#include "asterisk/channel.h"
#include "asterisk/config.h"
#include "asterisk/pbx.h"
#include "asterisk/module.h"
#include "asterisk/cli.h"
#include "asterisk/lock.h"
#include "asterisk/res_odbc.h"
#include "asterisk/time.h"
#include "asterisk/astobj2.h"
#include "asterisk/app.h"
#include "asterisk/strings.h"
#include "asterisk/threadstorage.h"
#include "asterisk/data.h"

/*** DOCUMENTATION
   <function name="ODBC" language="en_US">
      <synopsis>
         Controls ODBC transaction properties.
      </synopsis>
      <syntax>
         <parameter name="property" required="true">
            <enumlist>
               <enum name="transaction">
                  <para>Gets or sets the active transaction ID.  If set, and the transaction ID does not
                  exist and a <replaceable>database name</replaceable> is specified as an argument, it will be created.</para>
               </enum>
               <enum name="forcecommit">
                  <para>Controls whether a transaction will be automatically committed when the channel
                  hangs up.  Defaults to false.  If a <replaceable>transaction ID</replaceable> is specified in the optional argument,
                  the property will be applied to that ID, otherwise to the current active ID.</para>
               </enum>
               <enum name="isolation">
                  <para>Controls the data isolation on uncommitted transactions.  May be one of the
                  following: <literal>read_committed</literal>, <literal>read_uncommitted</literal>,
                  <literal>repeatable_read</literal>, or <literal>serializable</literal>.  Defaults to the
                  database setting in <filename>res_odbc.conf</filename> or <literal>read_committed</literal>
                  if not specified.  If a <replaceable>transaction ID</replaceable> is specified as an optional argument, it will be
                  applied to that ID, otherwise the current active ID.</para>
               </enum>
            </enumlist>
         </parameter>
         <parameter name="argument" required="false" />
      </syntax>
      <description>
         <para>The ODBC() function allows setting several properties to influence how a connected
         database processes transactions.</para>
      </description>
   </function>
   <application name="ODBC_Commit" language="en_US">
      <synopsis>
         Commits a currently open database transaction.
      </synopsis>
      <syntax>
         <parameter name="transaction ID" required="no" />
      </syntax>
      <description>
         <para>Commits the database transaction specified by <replaceable>transaction ID</replaceable>
         or the current active transaction, if not specified.</para>
      </description>
   </application>
   <application name="ODBC_Rollback" language="en_US">
      <synopsis>
         Rollback a currently open database transaction.
      </synopsis>
      <syntax>
         <parameter name="transaction ID" required="no" />
      </syntax>
      <description>
         <para>Rolls back the database transaction specified by <replaceable>transaction ID</replaceable>
         or the current active transaction, if not specified.</para>
      </description>
   </application>
 ***/

struct odbc_class
{
   AST_LIST_ENTRY(odbc_class) list;
   char name[80];
   char dsn[80];
   char *username;
   char *password;
   char *sanitysql;
   SQLHENV env;
   unsigned int haspool:1;              /*!< Boolean - TDS databases need this */
   unsigned int delme:1;                /*!< Purge the class */
   unsigned int backslash_is_escape:1;  /*!< On this database, the backslash is a native escape sequence */
   unsigned int forcecommit:1;          /*!< Should uncommitted transactions be auto-committed on handle release? */
   unsigned int allow_empty_strings:1;  /*!< Implicit conversion from an empty string to a number is valid for this database */
   unsigned int isolation;              /*!< Flags for how the DB should deal with data in other, uncommitted transactions */
   unsigned int limit;                  /*!< Maximum number of database handles we will allow */
   int count;                           /*!< Running count of pooled connections */
   unsigned int idlecheck;              /*!< Recheck the connection if it is idle for this long (in seconds) */
   unsigned int conntimeout;            /*!< Maximum time the connection process should take */
   /*! When a connection fails, cache that failure for how long? */
   struct timeval negative_connection_cache;
   /*! When a connection fails, when did that last occur? */
   struct timeval last_negative_connect;
   /*! List of handles associated with this class */
   struct ao2_container *obj_container;
};

static struct ao2_container *class_container;

static AST_RWLIST_HEAD_STATIC(odbc_tables, odbc_cache_tables);

static odbc_status odbc_obj_connect(struct odbc_obj *obj);
static odbc_status odbc_obj_disconnect(struct odbc_obj *obj);
static int odbc_register_class(struct odbc_class *class, int connect);
static void odbc_txn_free(void *data);
static void odbc_release_obj2(struct odbc_obj *obj, struct odbc_txn_frame *tx);

AST_THREADSTORAGE(errors_buf);

static const struct ast_datastore_info txn_info = {
   .type = "ODBC_Transaction",
   .destroy = odbc_txn_free,
};

struct odbc_txn_frame {
   AST_LIST_ENTRY(odbc_txn_frame) list;
   struct ast_channel *owner;
   struct odbc_obj *obj;        /*!< Database handle within which transacted statements are run */
   /*!\brief Is this record the current active transaction within the channel?
    * Note that the active flag is really only necessary for statements which
    * are triggered from the dialplan, as there isn't a direct correlation
    * between multiple statements.  Applications wishing to use transactions
    * may simply perform each statement on the same odbc_obj, which keeps the
    * transaction persistent.
    */
   unsigned int active:1;
   unsigned int forcecommit:1;     /*!< Should uncommitted transactions be auto-committed on handle release? */
   unsigned int isolation;         /*!< Flags for how the DB should deal with data in other, uncommitted transactions */
   char name[0];                   /*!< Name of this transaction ID */
};

#define DATA_EXPORT_ODBC_CLASS(MEMBER)          \
   MEMBER(odbc_class, name, AST_DATA_STRING)    \
   MEMBER(odbc_class, dsn, AST_DATA_STRING)     \
   MEMBER(odbc_class, username, AST_DATA_STRING)      \
   MEMBER(odbc_class, password, AST_DATA_PASSWORD)    \
   MEMBER(odbc_class, limit, AST_DATA_INTEGER)     \
   MEMBER(odbc_class, count, AST_DATA_INTEGER)     \
   MEMBER(odbc_class, forcecommit, AST_DATA_BOOLEAN)

AST_DATA_STRUCTURE(odbc_class, DATA_EXPORT_ODBC_CLASS);

static const char *isolation2text(int iso)
{
   if (iso == SQL_TXN_READ_COMMITTED) {
      return "read_committed";
   } else if (iso == SQL_TXN_READ_UNCOMMITTED) {
      return "read_uncommitted";
   } else if (iso == SQL_TXN_SERIALIZABLE) {
      return "serializable";
   } else if (iso == SQL_TXN_REPEATABLE_READ) {
      return "repeatable_read";
   } else {
      return "unknown";
   }
}

static int text2isolation(const char *txt)
{
   if (strncasecmp(txt, "read_", 5) == 0) {
      if (strncasecmp(txt + 5, "c", 1) == 0) {
         return SQL_TXN_READ_COMMITTED;
      } else if (strncasecmp(txt + 5, "u", 1) == 0) {
         return SQL_TXN_READ_UNCOMMITTED;
      } else {
         return 0;
      }
   } else if (strncasecmp(txt, "ser", 3) == 0) {
      return SQL_TXN_SERIALIZABLE;
   } else if (strncasecmp(txt, "rep", 3) == 0) {
      return SQL_TXN_REPEATABLE_READ;
   } else {
      return 0;
   }
}

static struct odbc_txn_frame *find_transaction(struct ast_channel *chan, struct odbc_obj *obj, const char *name, int active)
{
   struct ast_datastore *txn_store;
   AST_LIST_HEAD(, odbc_txn_frame) *oldlist;
   struct odbc_txn_frame *txn = NULL;

   if (!chan && obj && obj->txf && obj->txf->owner) {
      chan = obj->txf->owner;
   } else if (!chan) {
      /* No channel == no transaction */
      return NULL;
   }

   ast_channel_lock(chan);
   if ((txn_store = ast_channel_datastore_find(chan, &txn_info, NULL))) {
      oldlist = txn_store->data;
   } else {
      /* Need to create a new datastore */
      if (!(txn_store = ast_datastore_alloc(&txn_info, NULL))) {
         ast_log(LOG_ERROR, "Unable to allocate a new datastore.  Cannot create a new transaction.\n");
         ast_channel_unlock(chan);
         return NULL;
      }

      if (!(oldlist = ast_calloc(1, sizeof(*oldlist)))) {
         ast_log(LOG_ERROR, "Unable to allocate datastore list head.  Cannot create a new transaction.\n");
         ast_datastore_free(txn_store);
         ast_channel_unlock(chan);
         return NULL;
      }

      txn_store->data = oldlist;
      AST_LIST_HEAD_INIT(oldlist);
      ast_channel_datastore_add(chan, txn_store);
   }

   AST_LIST_LOCK(oldlist);
   ast_channel_unlock(chan);

   /* Scanning for an object is *fast*.  Scanning for a name is much slower. */
   if (obj != NULL || active == 1) {
      AST_LIST_TRAVERSE(oldlist, txn, list) {
         if (txn->obj == obj || txn->active) {
            AST_LIST_UNLOCK(oldlist);
            return txn;
         }
      }
   }

   if (name != NULL) {
      AST_LIST_TRAVERSE(oldlist, txn, list) {
         if (!strcasecmp(txn->name, name)) {
            AST_LIST_UNLOCK(oldlist);
            return txn;
         }
      }
   }

   /* Nothing found, create one */
   if (name && obj && (txn = ast_calloc(1, sizeof(*txn) + strlen(name) + 1))) {
      struct odbc_txn_frame *otxn;

      strcpy(txn->name, name); /* SAFE */
      txn->obj = obj;
      txn->isolation = obj->parent->isolation;
      txn->forcecommit = obj->parent->forcecommit;
      txn->owner = chan;
      txn->active = 1;

      /* On creation, the txn becomes active, and all others inactive */
      AST_LIST_TRAVERSE(oldlist, otxn, list) {
         otxn->active = 0;
      }
      AST_LIST_INSERT_TAIL(oldlist, txn, list);

      obj->txf = txn;
      obj->tx = 1;
   }
   AST_LIST_UNLOCK(oldlist);

   return txn;
}

static struct odbc_txn_frame *release_transaction(struct odbc_txn_frame *tx)
{
   if (!tx) {
      return NULL;
   }

   ast_debug(2, "release_transaction(%p) called (tx->obj = %p, tx->obj->txf = %p)\n", tx, tx->obj, tx->obj ? tx->obj->txf : NULL);

   /* If we have an owner, disassociate */
   if (tx->owner) {
      struct ast_datastore *txn_store;
      AST_LIST_HEAD(, odbc_txn_frame) *oldlist;

      ast_channel_lock(tx->owner);
      if ((txn_store = ast_channel_datastore_find(tx->owner, &txn_info, NULL))) {
         oldlist = txn_store->data;
         AST_LIST_LOCK(oldlist);
         AST_LIST_REMOVE(oldlist, tx, list);
         AST_LIST_UNLOCK(oldlist);
      }
      ast_channel_unlock(tx->owner);
      tx->owner = NULL;
   }

   if (tx->obj) {
      /* If we have any uncommitted transactions, they are handled when we release the object */
      struct odbc_obj *obj = tx->obj;
      /* Prevent recursion during destruction */
      tx->obj->txf = NULL;
      tx->obj = NULL;
      odbc_release_obj2(obj, tx);
   }
   ast_free(tx);
   return NULL;
}

static void odbc_txn_free(void *vdata)
{
   struct odbc_txn_frame *tx;
   AST_LIST_HEAD(, odbc_txn_frame) *oldlist = vdata;

   ast_debug(2, "odbc_txn_free(%p) called\n", vdata);

   AST_LIST_LOCK(oldlist);
   while ((tx = AST_LIST_REMOVE_HEAD(oldlist, list))) {
      release_transaction(tx);
   }
   AST_LIST_UNLOCK(oldlist);
   AST_LIST_HEAD_DESTROY(oldlist);
   ast_free(oldlist);
}

static int mark_transaction_active(struct ast_channel *chan, struct odbc_txn_frame *tx)
{
   struct ast_datastore *txn_store;
   AST_LIST_HEAD(, odbc_txn_frame) *oldlist;
   struct odbc_txn_frame *active = NULL, *txn;

   if (!chan && tx && tx->owner) {
      chan = tx->owner;
   }

   if (!chan) {
      return -1;
   }

   ast_channel_lock(chan);
   if (!(txn_store = ast_channel_datastore_find(chan, &txn_info, NULL))) {
      ast_channel_unlock(chan);
      return -1;
   }

   oldlist = txn_store->data;
   AST_LIST_LOCK(oldlist);
   AST_LIST_TRAVERSE(oldlist, txn, list) {
      if (txn == tx) {
         txn->active = 1;
         active = txn;
      } else {
         txn->active = 0;
      }
   }
   AST_LIST_UNLOCK(oldlist);
   ast_channel_unlock(chan);
   return active ? 0 : -1;
}

static void odbc_class_destructor(void *data)
{
   struct odbc_class *class = data;
   /* Due to refcounts, we can safely assume that any objects with a reference
    * to us will prevent our destruction, so we don't need to worry about them.
    */
   if (class->username) {
      ast_free(class->username);
   }
   if (class->password) {
      ast_free(class->password);
   }
   if (class->sanitysql) {
      ast_free(class->sanitysql);
   }
   ao2_ref(class->obj_container, -1);
   SQLFreeHandle(SQL_HANDLE_ENV, class->env);
}

static int null_hash_fn(const void *obj, const int flags)
{
   return 0;
}

static void odbc_obj_destructor(void *data)
{
   struct odbc_obj *obj = data;
   struct odbc_class *class = obj->parent;
   obj->parent = NULL;
   odbc_obj_disconnect(obj);
   ao2_ref(class, -1);
}

static void destroy_table_cache(struct odbc_cache_tables *table) {
   struct odbc_cache_columns *col;
   ast_debug(1, "Destroying table cache for %s\n", table->table);
   AST_RWLIST_WRLOCK(&table->columns);
   while ((col = AST_RWLIST_REMOVE_HEAD(&table->columns, list))) {
      ast_free(col);
   }
   AST_RWLIST_UNLOCK(&table->columns);
   AST_RWLIST_HEAD_DESTROY(&table->columns);
   ast_free(table);
}

/*!
 * \brief Find or create an entry describing the table specified.
 * \param database Name of an ODBC class on which to query the table
 * \param tablename Tablename to describe
 * \retval A structure describing the table layout, or NULL, if the table is not found or another error occurs.
 * When a structure is returned, the contained columns list will be
 * rdlock'ed, to ensure that it will be retained in memory.
 * \since 1.6.1
 */
struct odbc_cache_tables *ast_odbc_find_table(const char *database, const char *tablename)
{
   struct odbc_cache_tables *tableptr;
   struct odbc_cache_columns *entry;
   char columnname[80];
   SQLLEN sqlptr;
   SQLHSTMT stmt = NULL;
   int res = 0, error = 0, try = 0;
   struct odbc_obj *obj = ast_odbc_request_obj(database, 0);

   AST_RWLIST_RDLOCK(&odbc_tables);
   AST_RWLIST_TRAVERSE(&odbc_tables, tableptr, list) {
      if (strcmp(tableptr->connection, database) == 0 && strcmp(tableptr->table, tablename) == 0) {
         break;
      }
   }
   if (tableptr) {
      AST_RWLIST_RDLOCK(&tableptr->columns);
      AST_RWLIST_UNLOCK(&odbc_tables);
      if (obj) {
         ast_odbc_release_obj(obj);
      }
      return tableptr;
   }

   if (!obj) {
      ast_log(LOG_WARNING, "Unable to retrieve database handle for table description '%s@%s'\n", tablename, database);
      AST_RWLIST_UNLOCK(&odbc_tables);
      return NULL;
   }

   /* Table structure not already cached; build it now. */
   ao2_lock(obj);
   do {
      res = SQLAllocHandle(SQL_HANDLE_STMT, obj->con, &stmt);
      if ((res != SQL_SUCCESS) && (res != SQL_SUCCESS_WITH_INFO)) {
         if (try == 0) {
            try = 1;
            ast_odbc_sanity_check(obj);
            continue;
         }
         ast_log(LOG_WARNING, "SQL Alloc Handle failed on connection '%s'!\n", database);
         break;
      }

      res = SQLColumns(stmt, NULL, 0, NULL, 0, (unsigned char *)tablename, SQL_NTS, (unsigned char *)"%", SQL_NTS);
      if ((res != SQL_SUCCESS) && (res != SQL_SUCCESS_WITH_INFO)) {
         if (try == 0) {
            try = 1;
            SQLFreeHandle(SQL_HANDLE_STMT, stmt);
            ast_odbc_sanity_check(obj);
            continue;
         }
         ast_log(LOG_ERROR, "Unable to query database columns on connection '%s'.\n", database);
         break;
      }

      if (!(tableptr = ast_calloc(sizeof(char), sizeof(*tableptr) + strlen(database) + 1 + strlen(tablename) + 1))) {
         ast_log(LOG_ERROR, "Out of memory creating entry for table '%s' on connection '%s'\n", tablename, database);
         break;
      }

      tableptr->connection = (char *)tableptr + sizeof(*tableptr);
      tableptr->table = (char *)tableptr + sizeof(*tableptr) + strlen(database) + 1;
      strcpy(tableptr->connection, database); /* SAFE */
      strcpy(tableptr->table, tablename); /* SAFE */
      AST_RWLIST_HEAD_INIT(&(tableptr->columns));

      while ((res = SQLFetch(stmt)) != SQL_NO_DATA && res != SQL_ERROR) {
         SQLGetData(stmt,  4, SQL_C_CHAR, columnname, sizeof(columnname), &sqlptr);

         if (!(entry = ast_calloc(sizeof(char), sizeof(*entry) + strlen(columnname) + 1))) {
            ast_log(LOG_ERROR, "Out of memory creating entry for column '%s' in table '%s' on connection '%s'\n", columnname, tablename, database);
            error = 1;
            break;
         }
         entry->name = (char *)entry + sizeof(*entry);
         strcpy(entry->name, columnname);

         SQLGetData(stmt,  5, SQL_C_SHORT, &entry->type, sizeof(entry->type), NULL);
         SQLGetData(stmt,  7, SQL_C_LONG, &entry->size, sizeof(entry->size), NULL);
         SQLGetData(stmt,  9, SQL_C_SHORT, &entry->decimals, sizeof(entry->decimals), NULL);
         SQLGetData(stmt, 10, SQL_C_SHORT, &entry->radix, sizeof(entry->radix), NULL);
         SQLGetData(stmt, 11, SQL_C_SHORT, &entry->nullable, sizeof(entry->nullable), NULL);
         SQLGetData(stmt, 16, SQL_C_LONG, &entry->octetlen, sizeof(entry->octetlen), NULL);

         /* Specification states that the octenlen should be the maximum number of bytes
          * returned in a char or binary column, but it seems that some drivers just set
          * it to NULL. (Bad Postgres! No biscuit!) */
         if (entry->octetlen == 0) {
            entry->octetlen = entry->size;
         }

         ast_verb(10, "Found %s column with type %hd with len %ld, octetlen %ld, and numlen (%hd,%hd)\n", entry->name, entry->type, (long) entry->size, (long) entry->octetlen, entry->decimals, entry->radix);
         /* Insert column info into column list */
         AST_LIST_INSERT_TAIL(&(tableptr->columns), entry, list);
      }
      SQLFreeHandle(SQL_HANDLE_STMT, stmt);

      AST_RWLIST_INSERT_TAIL(&odbc_tables, tableptr, list);
      AST_RWLIST_RDLOCK(&(tableptr->columns));
      break;
   } while (1);
   ao2_unlock(obj);

   AST_RWLIST_UNLOCK(&odbc_tables);

   if (error) {
      destroy_table_cache(tableptr);
      tableptr = NULL;
   }
   if (obj) {
      ast_odbc_release_obj(obj);
   }
   return tableptr;
}

struct odbc_cache_columns *ast_odbc_find_column(struct odbc_cache_tables *table, const char *colname)
{
   struct odbc_cache_columns *col;
   AST_RWLIST_TRAVERSE(&table->columns, col, list) {
      if (strcasecmp(col->name, colname) == 0) {
         return col;
      }
   }
   return NULL;
}

int ast_odbc_clear_cache(const char *database, const char *tablename)
{
   struct odbc_cache_tables *tableptr;

   AST_RWLIST_WRLOCK(&odbc_tables);
   AST_RWLIST_TRAVERSE_SAFE_BEGIN(&odbc_tables, tableptr, list) {
      if (strcmp(tableptr->connection, database) == 0 && strcmp(tableptr->table, tablename) == 0) {
         AST_LIST_REMOVE_CURRENT(list);
         destroy_table_cache(tableptr);
         break;
      }
   }
   AST_RWLIST_TRAVERSE_SAFE_END
   AST_RWLIST_UNLOCK(&odbc_tables);
   return tableptr ? 0 : -1;
}

SQLHSTMT ast_odbc_direct_execute(struct odbc_obj *obj, SQLHSTMT (*exec_cb)(struct odbc_obj *obj, void *data), void *data)
{
   int attempt;
   SQLHSTMT stmt;

   ao2_lock(obj);

   for (attempt = 0; attempt < 2; attempt++) {
      stmt = exec_cb(obj, data);

      if (stmt) {
         break;
      } else if (obj->tx) {
         ast_log(LOG_WARNING, "Failed to execute, but unable to reconnect, as we're transactional.\n");
         break;
      } else if (attempt == 0) {
         ast_log(LOG_WARNING, "SQL Execute error! Verifying connection to %s [%s]...\n", obj->parent->name, obj->parent->dsn);
      }
      if (!ast_odbc_sanity_check(obj)) {
         break;
      }
   }

   ao2_unlock(obj);

   return stmt;
}

SQLHSTMT ast_odbc_prepare_and_execute(struct odbc_obj *obj, SQLHSTMT (*prepare_cb)(struct odbc_obj *obj, void *data), void *data)
{
   int res = 0, i, attempt;
   SQLINTEGER nativeerror=0, numfields=0;
   SQLSMALLINT diagbytes=0;
   unsigned char state[10], diagnostic[256];
   SQLHSTMT stmt;

   ao2_lock(obj);

   for (attempt = 0; attempt < 2; attempt++) {
      /* This prepare callback may do more than just prepare -- it may also
       * bind parameters, bind results, etc.  The real key, here, is that
       * when we disconnect, all handles become invalid for most databases.
       * We must therefore redo everything when we establish a new
       * connection. */
      stmt = prepare_cb(obj, data);

      if (stmt) {
         res = SQLExecute(stmt);
         if ((res != SQL_SUCCESS) && (res != SQL_SUCCESS_WITH_INFO) && (res != SQL_NO_DATA)) {
            if (res == SQL_ERROR) {
               SQLGetDiagField(SQL_HANDLE_STMT, stmt, 1, SQL_DIAG_NUMBER, &numfields, SQL_IS_INTEGER, &diagbytes);
               for (i = 0; i < numfields; i++) {
                  SQLGetDiagRec(SQL_HANDLE_STMT, stmt, i + 1, state, &nativeerror, diagnostic, sizeof(diagnostic), &diagbytes);
                  ast_log(LOG_WARNING, "SQL Execute returned an error %d: %s: %s (%d)\n", res, state, diagnostic, diagbytes);
                  if (i > 10) {
                     ast_log(LOG_WARNING, "Oh, that was good.  There are really %d diagnostics?\n", (int)numfields);
                     break;
                  }
               }
            }

            if (obj->tx) {
               ast_log(LOG_WARNING, "SQL Execute error, but unable to reconnect, as we're transactional.\n");
               break;
            } else {
               ast_log(LOG_WARNING, "SQL Execute error %d! Verifying connection to %s [%s]...\n", res, obj->parent->name, obj->parent->dsn);
               SQLFreeHandle(SQL_HANDLE_STMT, stmt);
               stmt = NULL;

               obj->up = 0;
               /*
                * While this isn't the best way to try to correct an error, this won't automatically
                * fail when the statement handle invalidates.
                */
               if (!ast_odbc_sanity_check(obj)) {
                  break;
               }
               continue;
            }
         } else {
            obj->last_used = ast_tvnow();
         }
         break;
      } else if (attempt == 0) {
         ast_odbc_sanity_check(obj);
      }
   }

   ao2_unlock(obj);

   return stmt;
}

int ast_odbc_smart_execute(struct odbc_obj *obj, SQLHSTMT stmt)
{
   int res = 0, i;
   SQLINTEGER nativeerror=0, numfields=0;
   SQLSMALLINT diagbytes=0;
   unsigned char state[10], diagnostic[256];

   ao2_lock(obj);

   res = SQLExecute(stmt);
   if ((res != SQL_SUCCESS) && (res != SQL_SUCCESS_WITH_INFO) && (res != SQL_NO_DATA)) {
      if (res == SQL_ERROR) {
         SQLGetDiagField(SQL_HANDLE_STMT, stmt, 1, SQL_DIAG_NUMBER, &numfields, SQL_IS_INTEGER, &diagbytes);
         for (i = 0; i < numfields; i++) {
            SQLGetDiagRec(SQL_HANDLE_STMT, stmt, i + 1, state, &nativeerror, diagnostic, sizeof(diagnostic), &diagbytes);
            ast_log(LOG_WARNING, "SQL Execute returned an error %d: %s: %s (%d)\n", res, state, diagnostic, diagbytes);
            if (i > 10) {
               ast_log(LOG_WARNING, "Oh, that was good.  There are really %d diagnostics?\n", (int)numfields);
               break;
            }
         }
      }
   } else {
      obj->last_used = ast_tvnow();
   }

   ao2_unlock(obj);

   return res;
}

SQLRETURN ast_odbc_ast_str_SQLGetData(struct ast_str **buf, int pmaxlen, SQLHSTMT StatementHandle, SQLUSMALLINT ColumnNumber, SQLSMALLINT TargetType, SQLLEN *StrLen_or_Ind)
{
   SQLRETURN res;

   if (pmaxlen == 0) {
      if (SQLGetData(StatementHandle, ColumnNumber, TargetType, ast_str_buffer(*buf), 0, StrLen_or_Ind) == SQL_SUCCESS_WITH_INFO) {
         ast_str_make_space(buf, *StrLen_or_Ind + 1);
      }
   } else if (pmaxlen > 0) {
      ast_str_make_space(buf, pmaxlen);
   }
   res = SQLGetData(StatementHandle, ColumnNumber, TargetType, ast_str_buffer(*buf), ast_str_size(*buf), StrLen_or_Ind);
   ast_str_update(*buf);

   return res;
}

int ast_odbc_sanity_check(struct odbc_obj *obj) 
{
   char *test_sql = "select 1";
   SQLHSTMT stmt;
   int res = 0;

   if (!ast_strlen_zero(obj->parent->sanitysql))
      test_sql = obj->parent->sanitysql;

   if (obj->up) {
      res = SQLAllocHandle(SQL_HANDLE_STMT, obj->con, &stmt);
      if ((res != SQL_SUCCESS) && (res != SQL_SUCCESS_WITH_INFO)) {
         obj->up = 0;
      } else {
         res = SQLPrepare(stmt, (unsigned char *)test_sql, SQL_NTS);
         if ((res != SQL_SUCCESS) && (res != SQL_SUCCESS_WITH_INFO)) {
            obj->up = 0;
         } else {
            res = SQLExecute(stmt);
            if ((res != SQL_SUCCESS) && (res != SQL_SUCCESS_WITH_INFO)) {
               obj->up = 0;
            }
         }
      }
      SQLFreeHandle (SQL_HANDLE_STMT, stmt);
   }

   if (!obj->up && !obj->tx) { /* Try to reconnect! */
      ast_log(LOG_WARNING, "Connection is down attempting to reconnect...\n");
      odbc_obj_disconnect(obj);
      odbc_obj_connect(obj);
   }
   return obj->up;
}

static int load_odbc_config(void)
{
   static char *cfg = "res_odbc.conf";
   struct ast_config *config;
   struct ast_variable *v;
   char *cat;
   const char *dsn, *username, *password, *sanitysql;
   int enabled, pooling, limit, bse, conntimeout, forcecommit, isolation, allow_empty_strings;
   struct timeval ncache = { 0, 0 };
   unsigned int idlecheck;
   int preconnect = 0, res = 0;
   struct ast_flags config_flags = { 0 };

   struct odbc_class *new;

   config = ast_config_load(cfg, config_flags);
   if (config == CONFIG_STATUS_FILEMISSING || config == CONFIG_STATUS_FILEINVALID) {
      ast_log(LOG_WARNING, "Unable to load config file res_odbc.conf\n");
      return -1;
   }
   for (cat = ast_category_browse(config, NULL); cat; cat=ast_category_browse(config, cat)) {
      if (!strcasecmp(cat, "ENV")) {
         for (v = ast_variable_browse(config, cat); v; v = v->next) {
            setenv(v->name, v->value, 1);
            ast_log(LOG_NOTICE, "Adding ENV var: %s=%s\n", v->name, v->value);
         }
      } else {
         /* Reset all to defaults for each class of odbc connections */
         dsn = username = password = sanitysql = NULL;
         enabled = 1;
         preconnect = idlecheck = 0;
         pooling = 0;
         limit = 0;
         bse = 1;
         conntimeout = 10;
         forcecommit = 0;
         allow_empty_strings = 1;
         isolation = SQL_TXN_READ_COMMITTED;
         for (v = ast_variable_browse(config, cat); v; v = v->next) {
            if (!strcasecmp(v->name, "pooling")) {
               if (ast_true(v->value))
                  pooling = 1;
            } else if (!strncasecmp(v->name, "share", 5)) {
               /* "shareconnections" is a little clearer in meaning than "pooling" */
               if (ast_false(v->value))
                  pooling = 1;
            } else if (!strcasecmp(v->name, "limit")) {
               sscanf(v->value, "%30d", &limit);
               if (ast_true(v->value) && !limit) {
                  ast_log(LOG_WARNING, "Limit should be a number, not a boolean: '%s'.  Setting limit to 1023 for ODBC class '%s'.\n", v->value, cat);
                  limit = 1023;
               } else if (ast_false(v->value)) {
                  ast_log(LOG_WARNING, "Limit should be a number, not a boolean: '%s'.  Disabling ODBC class '%s'.\n", v->value, cat);
                  enabled = 0;
                  break;
               }
            } else if (!strcasecmp(v->name, "idlecheck")) {
               sscanf(v->value, "%30u", &idlecheck);
            } else if (!strcasecmp(v->name, "enabled")) {
               enabled = ast_true(v->value);
            } else if (!strcasecmp(v->name, "pre-connect")) {
               preconnect = ast_true(v->value);
            } else if (!strcasecmp(v->name, "dsn")) {
               dsn = v->value;
            } else if (!strcasecmp(v->name, "username")) {
               username = v->value;
            } else if (!strcasecmp(v->name, "password")) {
               password = v->value;
            } else if (!strcasecmp(v->name, "sanitysql")) {
               sanitysql = v->value;
            } else if (!strcasecmp(v->name, "backslash_is_escape")) {
               bse = ast_true(v->value);
            } else if (!strcasecmp(v->name, "allow_empty_string_in_nontext")) {
               allow_empty_strings = ast_true(v->value);
            } else if (!strcasecmp(v->name, "connect_timeout")) {
               if (sscanf(v->value, "%d", &conntimeout) != 1 || conntimeout < 1) {
                  ast_log(LOG_WARNING, "connect_timeout must be a positive integer\n");
                  conntimeout = 10;
               }
            } else if (!strcasecmp(v->name, "negative_connection_cache")) {
               double dncache;
               if (sscanf(v->value, "%lf", &dncache) != 1 || dncache < 0) {
                  ast_log(LOG_WARNING, "negative_connection_cache must be a non-negative integer\n");
                  /* 5 minutes sounds like a reasonable default */
                  ncache.tv_sec = 300;
                  ncache.tv_usec = 0;
               } else {
                  ncache.tv_sec = (int)dncache;
                  ncache.tv_usec = (dncache - ncache.tv_sec) * 1000000;
               }
            } else if (!strcasecmp(v->name, "forcecommit")) {
               forcecommit = ast_true(v->value);
            } else if (!strcasecmp(v->name, "isolation")) {
               if ((isolation = text2isolation(v->value)) == 0) {
                  ast_log(LOG_ERROR, "Unrecognized value for 'isolation': '%s' in section '%s'\n", v->value, cat);
                  isolation = SQL_TXN_READ_COMMITTED;
               }
            }
         }

         if (enabled && !ast_strlen_zero(dsn)) {
            new = ao2_alloc(sizeof(*new), odbc_class_destructor);

            if (!new) {
               res = -1;
               break;
            }

            SQLAllocHandle(SQL_HANDLE_ENV, SQL_NULL_HANDLE, &new->env);
            res = SQLSetEnvAttr(new->env, SQL_ATTR_ODBC_VERSION, (void *) SQL_OV_ODBC3, 0);

            if ((res != SQL_SUCCESS) && (res != SQL_SUCCESS_WITH_INFO)) {
               ast_log(LOG_WARNING, "res_odbc: Error SetEnv\n");
               ao2_ref(new, -1);
               return res;
            }

            new->obj_container = ao2_container_alloc(1, null_hash_fn, ao2_match_by_addr);

            if (pooling) {
               new->haspool = pooling;
               if (limit) {
                  new->limit = limit;
               } else {
                  ast_log(LOG_WARNING, "Pooling without also setting a limit is pointless.  Changing limit from 0 to 5.\n");
                  new->limit = 5;
               }
            }

            new->backslash_is_escape = bse ? 1 : 0;
            new->forcecommit = forcecommit ? 1 : 0;
            new->isolation = isolation;
            new->idlecheck = idlecheck;
            new->conntimeout = conntimeout;
            new->negative_connection_cache = ncache;
            new->allow_empty_strings = allow_empty_strings ? 1 : 0;

            if (cat)
               ast_copy_string(new->name, cat, sizeof(new->name));
            if (dsn)
               ast_copy_string(new->dsn, dsn, sizeof(new->dsn));
            if (username && !(new->username = ast_strdup(username))) {
               ao2_ref(new, -1);
               break;
            }
            if (password && !(new->password = ast_strdup(password))) {
               ao2_ref(new, -1);
               break;
            }
            if (sanitysql && !(new->sanitysql = ast_strdup(sanitysql))) {
               ao2_ref(new, -1);
               break;
            }

            odbc_register_class(new, preconnect);
            ast_log(LOG_NOTICE, "Registered ODBC class '%s' dsn->[%s]\n", cat, dsn);
            ao2_ref(new, -1);
            new = NULL;
         }
      }
   }
   ast_config_destroy(config);
   return res;
}

static char *handle_cli_odbc_show(struct ast_cli_entry *e, int cmd, struct ast_cli_args *a)
{
   struct ao2_iterator aoi;
   struct odbc_class *class;
   struct odbc_obj *current;
   int length = 0;
   int which = 0;
   char *ret = NULL;

   switch (cmd) {
   case CLI_INIT:
      e->command = "odbc show";
      e->usage =
            "Usage: odbc show [class]\n"
            "       List settings of a particular ODBC class or,\n"
            "       if not specified, all classes.\n";
      return NULL;
   case CLI_GENERATE:
      if (a->pos != 2)
         return NULL;
      length = strlen(a->word);
      aoi = ao2_iterator_init(class_container, 0);
      while ((class = ao2_iterator_next(&aoi))) {
         if (!strncasecmp(a->word, class->name, length) && ++which > a->n) {
            ret = ast_strdup(class->name);
         }
         ao2_ref(class, -1);
         if (ret) {
            break;
         }
      }
      ao2_iterator_destroy(&aoi);
      if (!ret && !strncasecmp(a->word, "all", length) && ++which > a->n) {
         ret = ast_strdup("all");
      }
      return ret;
   }

   ast_cli(a->fd, "\nODBC DSN Settings\n");
   ast_cli(a->fd,   "-----------------\n\n");
   aoi = ao2_iterator_init(class_container, 0);
   while ((class = ao2_iterator_next(&aoi))) {
      if ((a->argc == 2) || (a->argc == 3 && !strcmp(a->argv[2], "all")) || (!strcmp(a->argv[2], class->name))) {
         int count = 0;
         char timestr[80];
         struct ast_tm tm;

         ast_localtime(&class->last_negative_connect, &tm, NULL);
         ast_strftime(timestr, sizeof(timestr), "%Y-%m-%d %T", &tm);
         ast_cli(a->fd, "  Name:   %s\n  DSN:    %s\n", class->name, class->dsn);
         ast_cli(a->fd, "    Last connection attempt: %s\n", timestr);

         if (class->haspool) {
            struct ao2_iterator aoi2 = ao2_iterator_init(class->obj_container, 0);

            ast_cli(a->fd, "  Pooled: Yes\n  Limit:  %d\n  Connections in use: %d\n", class->limit, class->count);

            while ((current = ao2_iterator_next(&aoi2))) {
               ao2_lock(current);
#ifdef DEBUG_THREADS
               ast_cli(a->fd, "    - Connection %d: %s (%s:%d %s)\n", ++count,
                  current->used ? "in use" :
                  current->up && ast_odbc_sanity_check(current) ? "connected" : "disconnected",
                  current->file, current->lineno, current->function);
#else
               ast_cli(a->fd, "    - Connection %d: %s\n", ++count,
                  current->used ? "in use" :
                  current->up && ast_odbc_sanity_check(current) ? "connected" : "disconnected");
#endif
               ao2_unlock(current);
               ao2_ref(current, -1);
            }
            ao2_iterator_destroy(&aoi2);
         } else {
            /* Should only ever be one of these (unless there are transactions) */
            struct ao2_iterator aoi2 = ao2_iterator_init(class->obj_container, 0);
            while ((current = ao2_iterator_next(&aoi2))) {
               ast_cli(a->fd, "  Pooled: No\n  Connected: %s\n", current->used ? "In use" :
                  current->up && ast_odbc_sanity_check(current) ? "Yes" : "No");
               ao2_ref(current, -1);
            }
            ao2_iterator_destroy(&aoi2);
         }
         ast_cli(a->fd, "\n");
      }
      ao2_ref(class, -1);
   }
   ao2_iterator_destroy(&aoi);

   return CLI_SUCCESS;
}

static struct ast_cli_entry cli_odbc[] = {
   AST_CLI_DEFINE(handle_cli_odbc_show, "List ODBC DSN(s)")
};

static int odbc_register_class(struct odbc_class *class, int preconnect)
{
   struct odbc_obj *obj;
   if (class) {
      ao2_link(class_container, class);
      /* I still have a reference in the caller, so a deref is NOT missing here. */

      if (preconnect) {
         /* Request and release builds a connection */
         obj = ast_odbc_request_obj(class->name, 0);
         if (obj) {
            ast_odbc_release_obj(obj);
         }
      }

      return 0;
   } else {
      ast_log(LOG_WARNING, "Attempted to register a NULL class?\n");
      return -1;
   }
}

static void odbc_release_obj2(struct odbc_obj *obj, struct odbc_txn_frame *tx)
{
   SQLINTEGER nativeerror=0, numfields=0;
   SQLSMALLINT diagbytes=0, i;
   unsigned char state[10], diagnostic[256];

   ast_debug(2, "odbc_release_obj2(%p) called (obj->txf = %p)\n", obj, obj->txf);
   if (tx) {
      ast_debug(1, "called on a transactional handle with %s\n", tx->forcecommit ? "COMMIT" : "ROLLBACK");
      if (SQLEndTran(SQL_HANDLE_DBC, obj->con, tx->forcecommit ? SQL_COMMIT : SQL_ROLLBACK) == SQL_ERROR) {
         /* Handle possible transaction commit failure */
         SQLGetDiagField(SQL_HANDLE_DBC, obj->con, 1, SQL_DIAG_NUMBER, &numfields, SQL_IS_INTEGER, &diagbytes);
         for (i = 0; i < numfields; i++) {
            SQLGetDiagRec(SQL_HANDLE_DBC, obj->con, i + 1, state, &nativeerror, diagnostic, sizeof(diagnostic), &diagbytes);
            ast_log(LOG_WARNING, "SQLEndTran returned an error: %s: %s\n", state, diagnostic);
            if (!strcmp((char *)state, "25S02") || !strcmp((char *)state, "08007")) {
               /* These codes mean that a commit failed and a transaction
                * is still active. We must rollback, or things will get
                * very, very weird for anybody using the handle next. */
               SQLEndTran(SQL_HANDLE_DBC, obj->con, SQL_ROLLBACK);
            }
            if (i > 10) {
               ast_log(LOG_WARNING, "Oh, that was good.  There are really %d diagnostics?\n", (int)numfields);
               break;
            }
         }
      }

      /* Transaction is done, reset autocommit */
      if (SQLSetConnectAttr(obj->con, SQL_ATTR_AUTOCOMMIT, (void *)SQL_AUTOCOMMIT_ON, 0) == SQL_ERROR) {
         SQLGetDiagField(SQL_HANDLE_DBC, obj->con, 1, SQL_DIAG_NUMBER, &numfields, SQL_IS_INTEGER, &diagbytes);
         for (i = 0; i < numfields; i++) {
            SQLGetDiagRec(SQL_HANDLE_DBC, obj->con, i + 1, state, &nativeerror, diagnostic, sizeof(diagnostic), &diagbytes);
            ast_log(LOG_WARNING, "SetConnectAttr (Autocommit) returned an error: %s: %s\n", state, diagnostic);
            if (i > 10) {
               ast_log(LOG_WARNING, "Oh, that was good.  There are really %d diagnostics?\n", (int)numfields);
               break;
            }
         }
      }
   }

#ifdef DEBUG_THREADS
   obj->file[0] = '\0';
   obj->function[0] = '\0';
   obj->lineno = 0;
#endif

   /* For pooled connections, this frees the connection to be
    * reused.  For non-pooled connections, it does nothing. */
   obj->used = 0;
   if (obj->txf) {
      /* Prevent recursion -- transaction is already closed out. */
      obj->txf->obj = NULL;
      obj->txf = release_transaction(obj->txf);
   }
   ao2_ref(obj, -1);
}

void ast_odbc_release_obj(struct odbc_obj *obj)
{
   struct odbc_txn_frame *tx = find_transaction(NULL, obj, NULL, 0);
   odbc_release_obj2(obj, tx);
}

int ast_odbc_backslash_is_escape(struct odbc_obj *obj)
{
   return obj->parent->backslash_is_escape;
}

int ast_odbc_allow_empty_string_in_nontext(struct odbc_obj *obj)
{
   return obj->parent->allow_empty_strings;
}

static int commit_exec(struct ast_channel *chan, const char *data)
{
   struct odbc_txn_frame *tx;
   SQLINTEGER nativeerror=0, numfields=0;
   SQLSMALLINT diagbytes=0, i;
   unsigned char state[10], diagnostic[256];

   if (ast_strlen_zero(data)) {
      tx = find_transaction(chan, NULL, NULL, 1);
   } else {
      tx = find_transaction(chan, NULL, data, 0);
   }

   pbx_builtin_setvar_helper(chan, "COMMIT_RESULT", "OK");

   if (tx) {
      if (SQLEndTran(SQL_HANDLE_DBC, tx->obj->con, SQL_COMMIT) == SQL_ERROR) {
         struct ast_str *errors = ast_str_thread_get(&errors_buf, 16);
         ast_str_reset(errors);

         /* Handle possible transaction commit failure */
         SQLGetDiagField(SQL_HANDLE_DBC, tx->obj->con, 1, SQL_DIAG_NUMBER, &numfields, SQL_IS_INTEGER, &diagbytes);
         for (i = 0; i < numfields; i++) {
            SQLGetDiagRec(SQL_HANDLE_DBC, tx->obj->con, i + 1, state, &nativeerror, diagnostic, sizeof(diagnostic), &diagbytes);
            ast_str_append(&errors, 0, "%s%s", ast_str_strlen(errors) ? "," : "", state);
            ast_log(LOG_WARNING, "SQLEndTran returned an error: %s: %s\n", state, diagnostic);
            if (i > 10) {
               ast_log(LOG_WARNING, "Oh, that was good.  There are really %d diagnostics?\n", (int)numfields);
               break;
            }
         }
         pbx_builtin_setvar_helper(chan, "COMMIT_RESULT", ast_str_buffer(errors));
      }
   }
   return 0;
}

static int rollback_exec(struct ast_channel *chan, const char *data)
{
   struct odbc_txn_frame *tx;
   SQLINTEGER nativeerror=0, numfields=0;
   SQLSMALLINT diagbytes=0, i;
   unsigned char state[10], diagnostic[256];

   if (ast_strlen_zero(data)) {
      tx = find_transaction(chan, NULL, NULL, 1);
   } else {
      tx = find_transaction(chan, NULL, data, 0);
   }

   pbx_builtin_setvar_helper(chan, "ROLLBACK_RESULT", "OK");

   if (tx) {
      if (SQLEndTran(SQL_HANDLE_DBC, tx->obj->con, SQL_ROLLBACK) == SQL_ERROR) {
         struct ast_str *errors = ast_str_thread_get(&errors_buf, 16);
         ast_str_reset(errors);

         /* Handle possible transaction commit failure */
         SQLGetDiagField(SQL_HANDLE_DBC, tx->obj->con, 1, SQL_DIAG_NUMBER, &numfields, SQL_IS_INTEGER, &diagbytes);
         for (i = 0; i < numfields; i++) {
            SQLGetDiagRec(SQL_HANDLE_DBC, tx->obj->con, i + 1, state, &nativeerror, diagnostic, sizeof(diagnostic), &diagbytes);
            ast_str_append(&errors, 0, "%s%s", ast_str_strlen(errors) ? "," : "", state);
            ast_log(LOG_WARNING, "SQLEndTran returned an error: %s: %s\n", state, diagnostic);
            if (i > 10) {
               ast_log(LOG_WARNING, "Oh, that was good.  There are really %d diagnostics?\n", (int)numfields);
               break;
            }
         }
         pbx_builtin_setvar_helper(chan, "ROLLBACK_RESULT", ast_str_buffer(errors));
      }
   }
   return 0;
}

static int aoro2_class_cb(void *obj, void *arg, int flags)
{
   struct odbc_class *class = obj;
   char *name = arg;
   if (!strcmp(class->name, name) && !class->delme) {
      return CMP_MATCH | CMP_STOP;
   }
   return 0;
}

#define USE_TX (void *)(long)1
#define NO_TX  (void *)(long)2
#define EOR_TX (void *)(long)3

static int aoro2_obj_cb(void *vobj, void *arg, int flags)
{
   struct odbc_obj *obj = vobj;
   ao2_lock(obj);
   if ((arg == NO_TX && !obj->tx) || (arg == EOR_TX && !obj->used) || (arg == USE_TX && obj->tx && !obj->used)) {
      obj->used = 1;
      ao2_unlock(obj);
      return CMP_MATCH | CMP_STOP;
   }
   ao2_unlock(obj);
   return 0;
}

/* This function should only be called for shared connections. Otherwise, the lack of
 * setting vobj->used breaks EOR_TX searching. For nonshared connections, use
 * aoro2_obj_cb instead. */
static int aoro2_obj_notx_cb(void *vobj, void *arg, int flags)
{
   struct odbc_obj *obj = vobj;
   if (!obj->tx) {
      return CMP_MATCH | CMP_STOP;
   }
   return 0;
}

struct odbc_obj *_ast_odbc_request_obj2(const char *name, struct ast_flags flags, const char *file, const char *function, int lineno)
{
   struct odbc_obj *obj = NULL;
   struct odbc_class *class;
   SQLINTEGER nativeerror=0, numfields=0;
   SQLSMALLINT diagbytes=0, i;
   unsigned char state[10], diagnostic[256];

   if (!(class = ao2_callback(class_container, 0, aoro2_class_cb, (char *) name))) {
      ast_debug(1, "Class '%s' not found!\n", name);
      return NULL;
   }

   ast_assert(ao2_ref(class, 0) > 1);

   if (class->haspool) {
      /* Recycle connections before building another */
      obj = ao2_callback(class->obj_container, 0, aoro2_obj_cb, EOR_TX);

      if (obj) {
         ast_assert(ao2_ref(obj, 0) > 1);
      }
      if (!obj && (ast_atomic_fetchadd_int(&class->count, +1) < class->limit) &&
            (time(NULL) > class->last_negative_connect.tv_sec + class->negative_connection_cache.tv_sec)) {
         obj = ao2_alloc(sizeof(*obj), odbc_obj_destructor);
         if (!obj) {
            class->count--;
            ao2_ref(class, -1);
            ast_debug(3, "Unable to allocate object\n");
            ast_atomic_fetchadd_int(&class->count, -1);
            return NULL;
         }
         ast_assert(ao2_ref(obj, 0) == 1);
         /* obj inherits the outstanding reference to class */
         obj->parent = class;
         class = NULL;
         if (odbc_obj_connect(obj) == ODBC_FAIL) {
            ast_log(LOG_WARNING, "Failed to connect to %s\n", name);
            ast_assert(ao2_ref(obj->parent, 0) > 0);
            /* Because it was never within the container, we have to manually decrement the count here */
            ast_atomic_fetchadd_int(&obj->parent->count, -1);
            ao2_ref(obj, -1);
            obj = NULL;
         } else {
            obj->used = 1;
            ao2_link(obj->parent->obj_container, obj);
         }
      } else {
         /* If construction fails due to the limit (or negative timecache), reverse our increment. */
         if (!obj) {
            ast_atomic_fetchadd_int(&class->count, -1);
         }
         /* Object is not constructed, so delete outstanding reference to class. */
         ao2_ref(class, -1);
         class = NULL;
      }

      if (!obj) {
         return NULL;
      }

      ao2_lock(obj);

      if (ast_test_flag(&flags, RES_ODBC_INDEPENDENT_CONNECTION)) {
         /* Ensure this connection has autocommit turned off. */
         if (SQLSetConnectAttr(obj->con, SQL_ATTR_AUTOCOMMIT, (void *)SQL_AUTOCOMMIT_OFF, 0) == SQL_ERROR) {
            SQLGetDiagField(SQL_HANDLE_DBC, obj->con, 1, SQL_DIAG_NUMBER, &numfields, SQL_IS_INTEGER, &diagbytes);
            for (i = 0; i < numfields; i++) {
               SQLGetDiagRec(SQL_HANDLE_DBC, obj->con, i + 1, state, &nativeerror, diagnostic, sizeof(diagnostic), &diagbytes);
               ast_log(LOG_WARNING, "SQLSetConnectAttr (Autocommit) returned an error: %s: %s\n", state, diagnostic);
               if (i > 10) {
                  ast_log(LOG_WARNING, "Oh, that was good.  There are really %d diagnostics?\n", (int)numfields);
                  break;
               }
            }
         }
      }
   } else if (ast_test_flag(&flags, RES_ODBC_INDEPENDENT_CONNECTION)) {
      /* Non-pooled connections -- but must use a separate connection handle */
      if (!(obj = ao2_callback(class->obj_container, 0, aoro2_obj_cb, USE_TX))) {
         ast_debug(1, "Object not found\n");
         obj = ao2_alloc(sizeof(*obj), odbc_obj_destructor);
         if (!obj) {
            ao2_ref(class, -1);
            ast_debug(3, "Unable to allocate object\n");
            return NULL;
         }
         /* obj inherits the outstanding reference to class */
         obj->parent = class;
         class = NULL;
         if (odbc_obj_connect(obj) == ODBC_FAIL) {
            ast_log(LOG_WARNING, "Failed to connect to %s\n", name);
            ao2_ref(obj, -1);
            obj = NULL;
         } else {
            obj->used = 1;
            ao2_link(obj->parent->obj_container, obj);
            ast_atomic_fetchadd_int(&obj->parent->count, +1);
         }
      }

      if (!obj) {
         return NULL;
      }

      ao2_lock(obj);

      if (SQLSetConnectAttr(obj->con, SQL_ATTR_AUTOCOMMIT, (void *)SQL_AUTOCOMMIT_OFF, 0) == SQL_ERROR) {
         SQLGetDiagField(SQL_HANDLE_DBC, obj->con, 1, SQL_DIAG_NUMBER, &numfields, SQL_IS_INTEGER, &diagbytes);
         for (i = 0; i < numfields; i++) {
            SQLGetDiagRec(SQL_HANDLE_DBC, obj->con, i + 1, state, &nativeerror, diagnostic, sizeof(diagnostic), &diagbytes);
            ast_log(LOG_WARNING, "SetConnectAttr (Autocommit) returned an error: %s: %s\n", state, diagnostic);
            if (i > 10) {
               ast_log(LOG_WARNING, "Oh, that was good.  There are really %d diagnostics?\n", (int)numfields);
               break;
            }
         }
      }
   } else {
      /* Non-pooled connection: multiple modules can use the same connection. */
      if ((obj = ao2_callback(class->obj_container, 0, aoro2_obj_notx_cb, NO_TX))) {
         /* Object is not constructed, so delete outstanding reference to class. */
         ast_assert(ao2_ref(class, 0) > 1);
         ao2_ref(class, -1);
         class = NULL;
      } else {
         /* No entry: build one */
         if (!(obj = ao2_alloc(sizeof(*obj), odbc_obj_destructor))) {
            ast_assert(ao2_ref(class, 0) > 1);
            ao2_ref(class, -1);
            ast_debug(3, "Unable to allocate object\n");
            return NULL;
         }
         /* obj inherits the outstanding reference to class */
         obj->parent = class;
         class = NULL;
         if (odbc_obj_connect(obj) == ODBC_FAIL) {
            ast_log(LOG_WARNING, "Failed to connect to %s\n", name);
            ao2_ref(obj, -1);
            obj = NULL;
         } else {
            ao2_link(obj->parent->obj_container, obj);
            ast_assert(ao2_ref(obj, 0) > 1);
         }
      }

      if (!obj) {
         return NULL;
      }

      ao2_lock(obj);

      if (SQLSetConnectAttr(obj->con, SQL_ATTR_AUTOCOMMIT, (void *)SQL_AUTOCOMMIT_ON, 0) == SQL_ERROR) {
         SQLGetDiagField(SQL_HANDLE_DBC, obj->con, 1, SQL_DIAG_NUMBER, &numfields, SQL_IS_INTEGER, &diagbytes);
         for (i = 0; i < numfields; i++) {
            SQLGetDiagRec(SQL_HANDLE_DBC, obj->con, i + 1, state, &nativeerror, diagnostic, sizeof(diagnostic), &diagbytes);
            ast_log(LOG_WARNING, "SetConnectAttr (Autocommit) returned an error: %s: %s\n", state, diagnostic);
            if (i > 10) {
               ast_log(LOG_WARNING, "Oh, that was good.  There are really %d diagnostics?\n", (int)numfields);
               break;
            }
         }
      }
   }

   ast_assert(obj != NULL);

   /* Set the isolation property */
   if (SQLSetConnectAttr(obj->con, SQL_ATTR_TXN_ISOLATION, (void *)(long)obj->parent->isolation, 0) == SQL_ERROR) {
      SQLGetDiagField(SQL_HANDLE_DBC, obj->con, 1, SQL_DIAG_NUMBER, &numfields, SQL_IS_INTEGER, &diagbytes);
      for (i = 0; i < numfields; i++) {
         SQLGetDiagRec(SQL_HANDLE_DBC, obj->con, i + 1, state, &nativeerror, diagnostic, sizeof(diagnostic), &diagbytes);
         ast_log(LOG_WARNING, "SetConnectAttr (Txn isolation) returned an error: %s: %s\n", state, diagnostic);
         if (i > 10) {
            ast_log(LOG_WARNING, "Oh, that was good.  There are really %d diagnostics?\n", (int)numfields);
            break;
         }
      }
   }

   if (ast_test_flag(&flags, RES_ODBC_CONNECTED) && !obj->up) {
      /* Check if this connection qualifies for reconnection, with negative connection cache time */
      if (time(NULL) > obj->parent->last_negative_connect.tv_sec + obj->parent->negative_connection_cache.tv_sec) {
         odbc_obj_connect(obj);
      }
   } else if (ast_test_flag(&flags, RES_ODBC_SANITY_CHECK)) {
      ast_odbc_sanity_check(obj);
   } else if (obj->parent->idlecheck > 0 && ast_tvdiff_sec(ast_tvnow(), obj->last_used) > obj->parent->idlecheck) {
      odbc_obj_connect(obj);
   }

#ifdef DEBUG_THREADS
   ast_copy_string(obj->file, file, sizeof(obj->file));
   ast_copy_string(obj->function, function, sizeof(obj->function));
   obj->lineno = lineno;
#endif

   /* We had it locked because of the obj_connects we see here. */
   ao2_unlock(obj);

   ast_assert(class == NULL);

   ast_assert(ao2_ref(obj, 0) > 1);
   return obj;
}

struct odbc_obj *_ast_odbc_request_obj(const char *name, int check, const char *file, const char *function, int lineno)
{
   struct ast_flags flags = { check ? RES_ODBC_SANITY_CHECK : 0 };
   return _ast_odbc_request_obj2(name, flags, file, function, lineno);
}

struct odbc_obj *ast_odbc_retrieve_transaction_obj(struct ast_channel *chan, const char *objname)
{
   struct ast_datastore *txn_store;
   AST_LIST_HEAD(, odbc_txn_frame) *oldlist;
   struct odbc_txn_frame *txn = NULL;

   if (!chan) {
      /* No channel == no transaction */
      return NULL;
   }

   ast_channel_lock(chan);
   if ((txn_store = ast_channel_datastore_find(chan, &txn_info, NULL))) {
      oldlist = txn_store->data;
   } else {
      ast_channel_unlock(chan);
      return NULL;
   }

   AST_LIST_LOCK(oldlist);
   ast_channel_unlock(chan);

   AST_LIST_TRAVERSE(oldlist, txn, list) {
      if (txn->obj && txn->obj->parent && !strcmp(txn->obj->parent->name, objname)) {
         AST_LIST_UNLOCK(oldlist);
         return txn->obj;
      }
   }
   AST_LIST_UNLOCK(oldlist);
   return NULL;
}

static odbc_status odbc_obj_disconnect(struct odbc_obj *obj)
{
   int res;
   SQLINTEGER err;
   short int mlen;
   unsigned char msg[200], state[10];
   SQLHDBC con;

   /* Nothing to disconnect */
   if (!obj->con) {
      return ODBC_SUCCESS;
   }

   con = obj->con;
   obj->con = NULL;
   res = SQLDisconnect(con);

   if (obj->parent) {
      if (res == SQL_SUCCESS || res == SQL_SUCCESS_WITH_INFO) {
         ast_debug(1, "Disconnected %d from %s [%s]\n", res, obj->parent->name, obj->parent->dsn);
      } else {
         ast_debug(1, "res_odbc: %s [%s] already disconnected\n", obj->parent->name, obj->parent->dsn);
      }
   }

   if ((res = SQLFreeHandle(SQL_HANDLE_DBC, con)) == SQL_SUCCESS) {
      ast_debug(1, "Database handle %p deallocated\n", con);
   } else {
      SQLGetDiagRec(SQL_HANDLE_DBC, con, 1, state, &err, msg, 100, &mlen);
      ast_log(LOG_WARNING, "Unable to deallocate database handle %p? %d errno=%d %s\n", con, res, (int)err, msg);
   }

   obj->up = 0;
   return ODBC_SUCCESS;
}

static odbc_status odbc_obj_connect(struct odbc_obj *obj)
{
   int res;
   SQLINTEGER err;
   short int mlen;
   unsigned char msg[200], state[10];
#ifdef NEEDTRACE
   SQLINTEGER enable = 1;
   char *tracefile = "/tmp/odbc.trace";
#endif
   SQLHDBC con;

   if (obj->up) {
      odbc_obj_disconnect(obj);
      ast_log(LOG_NOTICE, "Re-connecting %s\n", obj->parent->name);
   } else {
      ast_assert(obj->con == NULL);
      ast_log(LOG_NOTICE, "Connecting %s\n", obj->parent->name);
   }

   res = SQLAllocHandle(SQL_HANDLE_DBC, obj->parent->env, &con);

   if ((res != SQL_SUCCESS) && (res != SQL_SUCCESS_WITH_INFO)) {
      ast_log(LOG_WARNING, "res_odbc: Error AllocHDB %d\n", res);
      obj->parent->last_negative_connect = ast_tvnow();
      return ODBC_FAIL;
   }
   SQLSetConnectAttr(con, SQL_LOGIN_TIMEOUT, (SQLPOINTER *)(long) obj->parent->conntimeout, 0);
   SQLSetConnectAttr(con, SQL_ATTR_CONNECTION_TIMEOUT, (SQLPOINTER *)(long) obj->parent->conntimeout, 0);
#ifdef NEEDTRACE
   SQLSetConnectAttr(con, SQL_ATTR_TRACE, &enable, SQL_IS_INTEGER);
   SQLSetConnectAttr(con, SQL_ATTR_TRACEFILE, tracefile, strlen(tracefile));
#endif

   res = SQLConnect(con,
         (SQLCHAR *) obj->parent->dsn, SQL_NTS,
         (SQLCHAR *) obj->parent->username, SQL_NTS,
         (SQLCHAR *) obj->parent->password, SQL_NTS);

   if ((res != SQL_SUCCESS) && (res != SQL_SUCCESS_WITH_INFO)) {
      SQLGetDiagRec(SQL_HANDLE_DBC, con, 1, state, &err, msg, 100, &mlen);
      obj->parent->last_negative_connect = ast_tvnow();
      ast_log(LOG_WARNING, "res_odbc: Error SQLConnect=%d errno=%d %s\n", res, (int)err, msg);
      if ((res = SQLFreeHandle(SQL_HANDLE_DBC, con)) != SQL_SUCCESS) {
         SQLGetDiagRec(SQL_HANDLE_DBC, con, 1, state, &err, msg, 100, &mlen);
         ast_log(LOG_WARNING, "Unable to deallocate database handle %p? %d errno=%d %s\n", con, res, (int)err, msg);
      }
      return ODBC_FAIL;
   } else {
      ast_log(LOG_NOTICE, "res_odbc: Connected to %s [%s]\n", obj->parent->name, obj->parent->dsn);
      obj->up = 1;
      obj->last_used = ast_tvnow();
   }

   obj->con = con;
   return ODBC_SUCCESS;
}

static int acf_transaction_read(struct ast_channel *chan, const char *cmd, char *data, char *buf, size_t len)
{
   AST_DECLARE_APP_ARGS(args,
      AST_APP_ARG(property);
      AST_APP_ARG(opt);
   );
   struct odbc_txn_frame *tx;

   AST_STANDARD_APP_ARGS(args, data);
   if (strcasecmp(args.property, "transaction") == 0) {
      if ((tx = find_transaction(chan, NULL, NULL, 1))) {
         ast_copy_string(buf, tx->name, len);
         return 0;
      }
   } else if (strcasecmp(args.property, "isolation") == 0) {
      if (!ast_strlen_zero(args.opt)) {
         tx = find_transaction(chan, NULL, args.opt, 0);
      } else {
         tx = find_transaction(chan, NULL, NULL, 1);
      }
      if (tx) {
         ast_copy_string(buf, isolation2text(tx->isolation), len);
         return 0;
      }
   } else if (strcasecmp(args.property, "forcecommit") == 0) {
      if (!ast_strlen_zero(args.opt)) {
         tx = find_transaction(chan, NULL, args.opt, 0);
      } else {
         tx = find_transaction(chan, NULL, NULL, 1);
      }
      if (tx) {
         ast_copy_string(buf, tx->forcecommit ? "1" : "0", len);
         return 0;
      }
   }
   return -1;
}

static int acf_transaction_write(struct ast_channel *chan, const char *cmd, char *s, const char *value)
{
   AST_DECLARE_APP_ARGS(args,
      AST_APP_ARG(property);
      AST_APP_ARG(opt);
   );
   struct odbc_txn_frame *tx;
   SQLINTEGER nativeerror=0, numfields=0;
   SQLSMALLINT diagbytes=0, i;
   unsigned char state[10], diagnostic[256];

   AST_STANDARD_APP_ARGS(args, s);
   if (strcasecmp(args.property, "transaction") == 0) {
      /* Set active transaction */
      struct odbc_obj *obj;
      if ((tx = find_transaction(chan, NULL, value, 0))) {
         mark_transaction_active(chan, tx);
      } else {
         /* No such transaction, create one */
         struct ast_flags flags = { RES_ODBC_INDEPENDENT_CONNECTION };
         if (ast_strlen_zero(args.opt) || !(obj = ast_odbc_request_obj2(args.opt, flags))) {
            ast_log(LOG_ERROR, "Could not create transaction: invalid database specification '%s'\n", S_OR(args.opt, ""));
            pbx_builtin_setvar_helper(chan, "ODBC_RESULT", "INVALID_DB");
            return -1;
         }
         if (!find_transaction(chan, obj, value, 0)) {
            pbx_builtin_setvar_helper(chan, "ODBC_RESULT", "FAILED_TO_CREATE");
            return -1;
         }
         obj->tx = 1;
      }
      pbx_builtin_setvar_helper(chan, "ODBC_RESULT", "OK");
      return 0;
   } else if (strcasecmp(args.property, "forcecommit") == 0) {
      /* Set what happens when an uncommitted transaction ends without explicit Commit or Rollback */
      if (ast_strlen_zero(args.opt)) {
         tx = find_transaction(chan, NULL, NULL, 1);
      } else {
         tx = find_transaction(chan, NULL, args.opt, 0);
      }
      if (!tx) {
         pbx_builtin_setvar_helper(chan, "ODBC_RESULT", "FAILED_TO_CREATE");
         return -1;
      }
      if (ast_true(value)) {
         tx->forcecommit = 1;
      } else if (ast_false(value)) {
         tx->forcecommit = 0;
      } else {
         ast_log(LOG_ERROR, "Invalid value for forcecommit: '%s'\n", S_OR(value, ""));
         pbx_builtin_setvar_helper(chan, "ODBC_RESULT", "INVALID_VALUE");
         return -1;
      }

      pbx_builtin_setvar_helper(chan, "ODBC_RESULT", "OK");
      return 0;
   } else if (strcasecmp(args.property, "isolation") == 0) {
      /* How do uncommitted transactions affect reads? */
      int isolation = text2isolation(value);
      if (ast_strlen_zero(args.opt)) {
         tx = find_transaction(chan, NULL, NULL, 1);
      } else {
         tx = find_transaction(chan, NULL, args.opt, 0);
      }
      if (!tx) {
         pbx_builtin_setvar_helper(chan, "ODBC_RESULT", "FAILED_TO_CREATE");
         return -1;
      }
      if (isolation == 0) {
         pbx_builtin_setvar_helper(chan, "ODBC_RESULT", "INVALID_VALUE");
         ast_log(LOG_ERROR, "Invalid isolation specification: '%s'\n", S_OR(value, ""));
      } else if (SQLSetConnectAttr(tx->obj->con, SQL_ATTR_TXN_ISOLATION, (void *)(long)isolation, 0) == SQL_ERROR) {
         pbx_builtin_setvar_helper(chan, "ODBC_RESULT", "SQL_ERROR");
         SQLGetDiagField(SQL_HANDLE_DBC, tx->obj->con, 1, SQL_DIAG_NUMBER, &numfields, SQL_IS_INTEGER, &diagbytes);
         for (i = 0; i < numfields; i++) {
            SQLGetDiagRec(SQL_HANDLE_DBC, tx->obj->con, i + 1, state, &nativeerror, diagnostic, sizeof(diagnostic), &diagbytes);
            ast_log(LOG_WARNING, "SetConnectAttr (Txn isolation) returned an error: %s: %s\n", state, diagnostic);
            if (i > 10) {
               ast_log(LOG_WARNING, "Oh, that was good.  There are really %d diagnostics?\n", (int)numfields);
               break;
            }
         }
      } else {
         pbx_builtin_setvar_helper(chan, "ODBC_RESULT", "OK");
         tx->isolation = isolation;
      }
      return 0;
   } else {
      ast_log(LOG_ERROR, "Unknown property: '%s'\n", args.property);
      return -1;
   }
}

static struct ast_custom_function odbc_function = {
   .name = "ODBC",
   .read = acf_transaction_read,
   .write = acf_transaction_write,
};

static const char * const app_commit = "ODBC_Commit";
static const char * const app_rollback = "ODBC_Rollback";

/*!
 * \internal
 * \brief Implements the channels provider.
 */
static int data_odbc_provider_handler(const struct ast_data_search *search,
      struct ast_data *root)
{
   struct ao2_iterator aoi, aoi2;
   struct odbc_class *class;
   struct odbc_obj *current;
   struct ast_data *data_odbc_class, *data_odbc_connections, *data_odbc_connection;
   struct ast_data *enum_node;
   int count;

   aoi = ao2_iterator_init(class_container, 0);
   while ((class = ao2_iterator_next(&aoi))) {
      data_odbc_class = ast_data_add_node(root, "class");
      if (!data_odbc_class) {
         ao2_ref(class, -1);
         continue;
      }

      ast_data_add_structure(odbc_class, data_odbc_class, class);

      if (!ao2_container_count(class->obj_container)) {
         ao2_ref(class, -1);
         continue;
      }

      data_odbc_connections = ast_data_add_node(data_odbc_class, "connections");
      if (!data_odbc_connections) {
         ao2_ref(class, -1);
         continue;
      }

      ast_data_add_bool(data_odbc_class, "shared", !class->haspool);
      /* isolation */
      enum_node = ast_data_add_node(data_odbc_class, "isolation");
      if (!enum_node) {
         ao2_ref(class, -1);
         continue;
      }
      ast_data_add_int(enum_node, "value", class->isolation);
      ast_data_add_str(enum_node, "text", isolation2text(class->isolation));

      count = 0;
      aoi2 = ao2_iterator_init(class->obj_container, 0);
      while ((current = ao2_iterator_next(&aoi2))) {
         data_odbc_connection = ast_data_add_node(data_odbc_connections, "connection");
         if (!data_odbc_connection) {
            ao2_ref(current, -1);
            continue;
         }

         ao2_lock(current);
         ast_data_add_str(data_odbc_connection, "status", current->used ? "in use" :
               current->up && ast_odbc_sanity_check(current) ? "connected" : "disconnected");
         ast_data_add_bool(data_odbc_connection, "transactional", current->tx);
         ao2_unlock(current);

         if (class->haspool) {
            ast_data_add_int(data_odbc_connection, "number", ++count);
         }

         ao2_ref(current, -1);
      }
      ao2_iterator_destroy(&aoi2);
      ao2_ref(class, -1);

      if (!ast_data_search_match(search, data_odbc_class)) {
         ast_data_remove_node(root, data_odbc_class);
      }
   }
   ao2_iterator_destroy(&aoi);
   return 0;
}

/*!
 * \internal
 * \brief /asterisk/res/odbc/listprovider.
 */
static const struct ast_data_handler odbc_provider = {
   .version = AST_DATA_HANDLER_VERSION,
   .get = data_odbc_provider_handler
};

static const struct ast_data_entry odbc_providers[] = {
   AST_DATA_ENTRY("/asterisk/res/odbc", &odbc_provider),
};

static int reload(void)
{
   struct odbc_cache_tables *table;
   struct odbc_class *class;
   struct odbc_obj *current;
   struct ao2_iterator aoi = ao2_iterator_init(class_container, 0);

   /* First, mark all to be purged */
   while ((class = ao2_iterator_next(&aoi))) {
      class->delme = 1;
      ao2_ref(class, -1);
   }
   ao2_iterator_destroy(&aoi);

   load_odbc_config();

   /* Purge remaining classes */

   /* Note on how this works; this is a case of circular references, so we
    * explicitly do NOT want to use a callback here (or we wind up in
    * recursive hell).
    *
    * 1. Iterate through all the classes.  Note that the classes will currently
    * contain two classes of the same name, one of which is marked delme and
    * will be purged when all remaining objects of the class are released, and
    * the other, which was created above when we re-parsed the config file.
    * 2. On each class, there is a reference held by the master container and
    * a reference held by each connection object.  There are two cases for
    * destruction of the class, noted below.  However, in all cases, all O-refs
    * (references to objects) will first be freed, which will cause the C-refs
    * (references to classes) to be decremented (but never to 0, because the
    * class container still has a reference).
    *    a) If the class has outstanding objects, the C-ref by the class
    *    container will then be freed, which leaves only C-refs by any
    *    outstanding objects.  When the final outstanding object is released
    *    (O-refs held by applications and dialplan functions), it will in turn
    *    free the final C-ref, causing class destruction.
    *    b) If the class has no outstanding objects, when the class container
    *    removes the final C-ref, the class will be destroyed.
    */
   aoi = ao2_iterator_init(class_container, 0);
   while ((class = ao2_iterator_next(&aoi))) { /* C-ref++ (by iterator) */
      if (class->delme) {
         struct ao2_iterator aoi2 = ao2_iterator_init(class->obj_container, 0);
         while ((current = ao2_iterator_next(&aoi2))) { /* O-ref++ (by iterator) */
            ao2_unlink(class->obj_container, current); /* unlink O-ref from class (reference handled implicitly) */
            ao2_ref(current, -1); /* O-ref-- (by iterator) */
            /* At this point, either
             * a) there's an outstanding O-ref, or
             * b) the object has already been destroyed.
             */
         }
         ao2_iterator_destroy(&aoi2);
         ao2_unlink(class_container, class); /* unlink C-ref from container (reference handled implicitly) */
         /* At this point, either
          * a) there's an outstanding O-ref, which holds an outstanding C-ref, or
          * b) the last remaining C-ref is held by the iterator, which will be
          * destroyed in the next step.
          */
      }
      ao2_ref(class, -1); /* C-ref-- (by iterator) */
   }
   ao2_iterator_destroy(&aoi);

   /* Empty the cache; it will get rebuilt the next time the tables are needed. */
   AST_RWLIST_WRLOCK(&odbc_tables);
   while ((table = AST_RWLIST_REMOVE_HEAD(&odbc_tables, list))) {
      destroy_table_cache(table);
   }
   AST_RWLIST_UNLOCK(&odbc_tables);

   return 0;
}

static int unload_module(void)
{
   /* Prohibit unloading */
   return -1;
}

static int load_module(void)
{
   if (!(class_container = ao2_container_alloc(1, null_hash_fn, ao2_match_by_addr)))
      return AST_MODULE_LOAD_DECLINE;
   if (load_odbc_config() == -1)
      return AST_MODULE_LOAD_DECLINE;
   ast_cli_register_multiple(cli_odbc, ARRAY_LEN(cli_odbc));
   ast_data_register_multiple(odbc_providers, ARRAY_LEN(odbc_providers));
   ast_register_application_xml(app_commit, commit_exec);
   ast_register_application_xml(app_rollback, rollback_exec);
   ast_custom_function_register(&odbc_function);
   ast_log(LOG_NOTICE, "res_odbc loaded.\n");
   return 0;
}

AST_MODULE_INFO(ASTERISK_GPL_KEY, AST_MODFLAG_GLOBAL_SYMBOLS | AST_MODFLAG_LOAD_ORDER, "ODBC resource",
      .load = load_module,
      .unload = unload_module,
      .reload = reload,
      .load_pri = AST_MODPRI_REALTIME_DEPEND,
          );