Wed Feb 11 12:00:31 2009

Asterisk developer's documentation


res_odbc.h File Reference

ODBC resource manager. More...

#include <sql.h>
#include <sqlext.h>
#include <sqltypes.h>

Go to the source code of this file.

Data Structures

struct  odbc_obj

Enumerations

enum  odbc_status { ODBC_SUCCESS = 0, ODBC_FAIL = -1 }

Functions

int ast_odbc_backslash_is_escape (struct odbc_obj *obj)
 Checks if the database natively supports backslash as an escape character.
SQLHSTMT ast_odbc_prepare_and_execute (struct odbc_obj *obj, SQLHSTMT(*prepare_cb)(struct odbc_obj *obj, void *data), void *data)
 Prepares, executes, and returns the resulting statement handle.
void ast_odbc_release_obj (struct odbc_obj *obj)
 Releases an ODBC object previously allocated by odbc_request_obj().
odbc_objast_odbc_request_obj (const char *name, int check)
 Retrieves a connected ODBC object.
int ast_odbc_sanity_check (struct odbc_obj *obj)
 Checks an ODBC object to ensure it is still connected.
int ast_odbc_smart_execute (struct odbc_obj *obj, SQLHSTMT stmt)
 Executes a prepared statement handle.


Detailed Description

ODBC resource manager.

Definition in file res_odbc.h.


Enumeration Type Documentation

enum odbc_status

Enumerator:
ODBC_SUCCESS 
ODBC_FAIL 

Definition at line 34 of file res_odbc.h.


Function Documentation

int ast_odbc_backslash_is_escape ( struct odbc_obj obj  ) 

Checks if the database natively supports backslash as an escape character.

Parameters:
obj The ODBC object
Returns:
Returns 1 if backslash is a native escape character, 0 if an ESCAPE clause is needed to support '\'

Definition at line 396 of file res_odbc.c.

References odbc_class::backslash_is_escape, and odbc_obj::parent.

Referenced by realtime_multi_odbc(), and realtime_odbc().

00397 {
00398    return obj->parent->backslash_is_escape;
00399 }

SQLHSTMT ast_odbc_prepare_and_execute ( struct odbc_obj obj,
SQLHSTMT(*)(struct odbc_obj *obj, void *data)  prepare_cb,
void *  data 
)

Prepares, executes, and returns the resulting statement handle.

Parameters:
obj The ODBC object
prepare_cb A function callback, which, when called, should return a statement handle prepared, with any necessary parameters or result columns bound.
data A parameter to be passed to the prepare_cb parameter function, indicating which statement handle is to be prepared.
Returns:
Returns a statement handle or NULL on error.

Definition at line 82 of file res_odbc.c.

References ast_log(), ast_tvnow(), LOG_WARNING, odbc_obj_connect(), and odbc_obj_disconnect().

Referenced by acf_odbc_read(), acf_odbc_write(), config_odbc(), realtime_multi_odbc(), realtime_odbc(), and update_odbc().

00083 {
00084    int res = 0, i, attempt;
00085    SQLINTEGER nativeerror=0, numfields=0;
00086    SQLSMALLINT diagbytes=0;
00087    unsigned char state[10], diagnostic[256];
00088    SQLHSTMT stmt;
00089 
00090    for (attempt = 0; attempt < 2; attempt++) {
00091       /* This prepare callback may do more than just prepare -- it may also
00092        * bind parameters, bind results, etc.  The real key, here, is that
00093        * when we disconnect, all handles become invalid for most databases.
00094        * We must therefore redo everything when we establish a new
00095        * connection. */
00096       stmt = prepare_cb(obj, data);
00097 
00098       if (stmt) {
00099          res = SQLExecute(stmt);
00100          if ((res != SQL_SUCCESS) && (res != SQL_SUCCESS_WITH_INFO) && (res != SQL_NO_DATA)) {
00101             if (res == SQL_ERROR) {
00102                SQLGetDiagField(SQL_HANDLE_STMT, stmt, 1, SQL_DIAG_NUMBER, &numfields, SQL_IS_INTEGER, &diagbytes);
00103                for (i = 0; i < numfields; i++) {
00104                   SQLGetDiagRec(SQL_HANDLE_STMT, stmt, i + 1, state, &nativeerror, diagnostic, sizeof(diagnostic), &diagbytes);
00105                   ast_log(LOG_WARNING, "SQL Execute returned an error %d: %s: %s (%d)\n", res, state, diagnostic, diagbytes);
00106                   if (i > 10) {
00107                      ast_log(LOG_WARNING, "Oh, that was good.  There are really %d diagnostics?\n", (int)numfields);
00108                      break;
00109                   }
00110                }
00111             }
00112 
00113             ast_log(LOG_WARNING, "SQL Execute error %d! Attempting a reconnect...\n", res);
00114             SQLFreeHandle(SQL_HANDLE_STMT, stmt);
00115             stmt = NULL;
00116 
00117             obj->up = 0;
00118             /*
00119              * While this isn't the best way to try to correct an error, this won't automatically
00120              * fail when the statement handle invalidates.
00121              */
00122             /* XXX Actually, it might, if we're using a non-pooled connection. Possible race here. XXX */
00123             odbc_obj_disconnect(obj);
00124             odbc_obj_connect(obj);
00125             continue;
00126          } else
00127             obj->last_used = ast_tvnow();
00128          break;
00129       } else {
00130          ast_log(LOG_WARNING, "SQL Prepare failed.  Attempting a reconnect...\n");
00131          odbc_obj_disconnect(obj);
00132          odbc_obj_connect(obj);
00133       }
00134    }
00135 
00136    return stmt;
00137 }

void ast_odbc_release_obj ( struct odbc_obj obj  ) 

Releases an ODBC object previously allocated by odbc_request_obj().

Parameters:
obj The ODBC object

Definition at line 389 of file res_odbc.c.

References odbc_obj::used.

Referenced by acf_odbc_read(), acf_odbc_write(), config_odbc(), odbc_register_class(), realtime_multi_odbc(), realtime_odbc(), and update_odbc().

00390 {
00391    /* For pooled connections, this frees the connection to be
00392     * reused.  For non-pooled connections, it does nothing. */
00393    obj->used = 0;
00394 }

struct odbc_obj* ast_odbc_request_obj ( const char *  name,
int  check 
)

Retrieves a connected ODBC object.

Parameters:
name The name of the ODBC class for which a connection is needed.
check Whether to ensure that a connection is valid before returning the handle. Usually unnecessary.
Returns:
Returns an ODBC object or NULL if there is no connection available with the requested name.
Connection classes may, in fact, contain multiple connection handles. If the connection is pooled, then each connection will be dedicated to the thread which requests it. Note that all connections should be released when the thread is done by calling odbc_release_obj(), below.

Definition at line 401 of file res_odbc.c.

References ast_calloc, AST_LIST_INSERT_HEAD, AST_LIST_INSERT_TAIL, AST_LIST_LOCK, AST_LIST_TRAVERSE, AST_LIST_UNLOCK, ast_log(), ast_mutex_destroy(), ast_mutex_init(), ast_odbc_sanity_check(), ast_tvdiff_ms(), ast_tvnow(), free, odbc_class::idlecheck, odbc_obj::last_used, odbc_class::list, LOG_WARNING, ODBC_FAIL, odbc_obj_connect(), odbc_obj::parent, and odbc_obj::used.

Referenced by acf_odbc_read(), acf_odbc_write(), config_odbc(), odbc_register_class(), realtime_multi_odbc(), realtime_odbc(), and update_odbc().

00402 {
00403    struct odbc_obj *obj = NULL;
00404    struct odbc_class *class;
00405 
00406    AST_LIST_LOCK(&odbc_list);
00407    AST_LIST_TRAVERSE(&odbc_list, class, list) {
00408       if (!strcmp(class->name, name))
00409          break;
00410    }
00411    AST_LIST_UNLOCK(&odbc_list);
00412 
00413    if (!class)
00414       return NULL;
00415 
00416    AST_LIST_LOCK(&class->odbc_obj);
00417    if (class->haspool) {
00418       /* Recycle connections before building another */
00419       AST_LIST_TRAVERSE(&class->odbc_obj, obj, list) {
00420          if (! obj->used) {
00421             obj->used = 1;
00422             break;
00423          }
00424       }
00425 
00426       if (!obj && (class->count < class->limit)) {
00427          class->count++;
00428          obj = ast_calloc(1, sizeof(*obj));
00429          if (!obj) {
00430             AST_LIST_UNLOCK(&class->odbc_obj);
00431             return NULL;
00432          }
00433          ast_mutex_init(&obj->lock);
00434          obj->parent = class;
00435          if (odbc_obj_connect(obj) == ODBC_FAIL) {
00436             ast_log(LOG_WARNING, "Failed to connect to %s\n", name);
00437             ast_mutex_destroy(&obj->lock);
00438             free(obj);
00439             obj = NULL;
00440             class->count--;
00441          } else {
00442             obj->used = 1;
00443             AST_LIST_INSERT_TAIL(&class->odbc_obj, obj, list);
00444          }
00445       }
00446    } else {
00447       /* Non-pooled connection: multiple modules can use the same connection. */
00448       AST_LIST_TRAVERSE(&class->odbc_obj, obj, list) {
00449          /* Non-pooled connection: if there is an entry, return it */
00450          break;
00451       }
00452 
00453       if (!obj) {
00454          /* No entry: build one */
00455          obj = ast_calloc(1, sizeof(*obj));
00456          if (!obj) {
00457             AST_LIST_UNLOCK(&class->odbc_obj);
00458             return NULL;
00459          }
00460          ast_mutex_init(&obj->lock);
00461          obj->parent = class;
00462          if (odbc_obj_connect(obj) == ODBC_FAIL) {
00463             ast_log(LOG_WARNING, "Failed to connect to %s\n", name);
00464             ast_mutex_destroy(&obj->lock);
00465             free(obj);
00466             obj = NULL;
00467          } else {
00468             AST_LIST_INSERT_HEAD(&class->odbc_obj, obj, list);
00469          }
00470       }
00471    }
00472    AST_LIST_UNLOCK(&class->odbc_obj);
00473 
00474    if (obj && check) {
00475       ast_odbc_sanity_check(obj);
00476    } else if (obj && obj->parent->idlecheck > 0 && ast_tvdiff_ms(ast_tvnow(), obj->last_used) / 1000 > obj->parent->idlecheck)
00477       odbc_obj_connect(obj);
00478 
00479    return obj;
00480 }

int ast_odbc_sanity_check ( struct odbc_obj obj  ) 

Checks an ODBC object to ensure it is still connected.

Parameters:
obj The ODBC object
Returns:
Returns 0 if connected, -1 otherwise.

Definition at line 182 of file res_odbc.c.

References ast_log(), odbc_obj::con, LOG_WARNING, odbc_obj_connect(), odbc_obj_disconnect(), and odbc_obj::up.

Referenced by ast_odbc_request_obj(), and odbc_show_command().

00183 {
00184    char *test_sql = "select 1";
00185    SQLHSTMT stmt;
00186    int res = 0;
00187 
00188    if (obj->up) {
00189       res = SQLAllocHandle(SQL_HANDLE_STMT, obj->con, &stmt);
00190       if ((res != SQL_SUCCESS) && (res != SQL_SUCCESS_WITH_INFO)) {
00191          obj->up = 0;
00192       } else {
00193          res = SQLPrepare(stmt, (unsigned char *)test_sql, SQL_NTS);
00194          if ((res != SQL_SUCCESS) && (res != SQL_SUCCESS_WITH_INFO)) {
00195             obj->up = 0;
00196          } else {
00197             res = SQLExecute(stmt);
00198             if ((res != SQL_SUCCESS) && (res != SQL_SUCCESS_WITH_INFO)) {
00199                obj->up = 0;
00200             }
00201          }
00202       }
00203       SQLFreeHandle (SQL_HANDLE_STMT, stmt);
00204    }
00205 
00206    if (!obj->up) { /* Try to reconnect! */
00207       ast_log(LOG_WARNING, "Connection is down attempting to reconnect...\n");
00208       odbc_obj_disconnect(obj);
00209       odbc_obj_connect(obj);
00210    }
00211    return obj->up;
00212 }

int ast_odbc_smart_execute ( struct odbc_obj obj,
SQLHSTMT  stmt 
)

Executes a prepared statement handle.

Parameters:
obj The non-NULL result of odbc_request_obj()
stmt The prepared statement handle
Returns:
Returns 0 on success or -1 on failure
This function was originally designed simply to execute a prepared statement handle and to retry if the initial execution failed. Unfortunately, it did this by disconnecting and reconnecting the database handle which on most databases causes the statement handle to become invalid. Therefore, this method has been deprecated in favor of odbc_prepare_and_execute() which allows the statement to be prepared multiple times, if necessary, in case of a loss of connection.

This function really only ever worked with MySQL, where the statement handle is not prepared on the server. If you are not using MySQL, you should avoid it.

Definition at line 139 of file res_odbc.c.

References ast_log(), ast_mutex_lock(), ast_mutex_unlock(), ast_tvnow(), odbc_obj::last_used, odbc_obj::lock, LOG_WARNING, odbc_obj_connect(), odbc_obj_disconnect(), and odbc_obj::up.

00140 {
00141    int res = 0, i;
00142    SQLINTEGER nativeerror=0, numfields=0;
00143    SQLSMALLINT diagbytes=0;
00144    unsigned char state[10], diagnostic[256];
00145 
00146    res = SQLExecute(stmt);
00147    if ((res != SQL_SUCCESS) && (res != SQL_SUCCESS_WITH_INFO) && (res != SQL_NO_DATA)) {
00148       if (res == SQL_ERROR) {
00149          SQLGetDiagField(SQL_HANDLE_STMT, stmt, 1, SQL_DIAG_NUMBER, &numfields, SQL_IS_INTEGER, &diagbytes);
00150          for (i = 0; i < numfields; i++) {
00151             SQLGetDiagRec(SQL_HANDLE_STMT, stmt, i + 1, state, &nativeerror, diagnostic, sizeof(diagnostic), &diagbytes);
00152             ast_log(LOG_WARNING, "SQL Execute returned an error %d: %s: %s (%d)\n", res, state, diagnostic, diagbytes);
00153             if (i > 10) {
00154                ast_log(LOG_WARNING, "Oh, that was good.  There are really %d diagnostics?\n", (int)numfields);
00155                break;
00156             }
00157          }
00158       }
00159 #if 0
00160       /* This is a really bad method of trying to correct a dead connection.  It
00161        * only ever really worked with MySQL.  It will not work with any other
00162        * database, since most databases prepare their statements on the server,
00163        * and if you disconnect, you invalidate the statement handle.  Hence, if
00164        * you disconnect, you're going to fail anyway, whether you try to execute
00165        * a second time or not.
00166        */
00167       ast_log(LOG_WARNING, "SQL Execute error %d! Attempting a reconnect...\n", res);
00168       ast_mutex_lock(&obj->lock);
00169       obj->up = 0;
00170       ast_mutex_unlock(&obj->lock);
00171       odbc_obj_disconnect(obj);
00172       odbc_obj_connect(obj);
00173       res = SQLExecute(stmt);
00174 #endif
00175    } else
00176       obj->last_used = ast_tvnow();
00177    
00178    return res;
00179 }


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