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conn.go
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conn.go
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//Package freetds provides interface to Microsoft Sql Server database by using freetds C lib: http://www.freetds.org.
package freetds
import (
"errors"
"fmt"
"regexp"
"strconv"
"strings"
"unsafe"
// "log"
"sync"
"time"
)
/*
#cgo LDFLAGS: -lsybdb
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include <errno.h>
#include <unistd.h>
#include <libgen.h>
#include <sybfront.h>
#include <sybdb.h>
static int err_handler(DBPROCESS * dbproc, int severity, int dberr, int oserr, char *dberrstr, char *oserrstr)
{
extern int errHandler(long dbprocAddr, int severity, int dberr, int oserr, char *dberrstr, char *oserrstr);
return errHandler((long)dbproc, severity, dberr, oserr, dberrstr, oserrstr);
}
static int msg_handler(DBPROCESS * dbproc, DBINT msgno, int msgstate, int severity, char *msgtext, char *srvname, char *procname, int line)
{
extern int msgHandler(long dbprocAddr, DBINT msgno, int msgstate, int severity, char *msgtext, char *srvname, char *procname, int line);
return msgHandler((long)dbproc, msgno, msgstate, severity, msgtext, srvname, procname, line);
}
static void my_dblogin(LOGINREC* login, char* username, char* password) {
dbsetlogintime(10);
dberrhandle(err_handler);
dbmsghandle(msg_handler);
DBSETLUSER(login, username);
DBSETLPWD(login, password);
dbsetlname(login, "UTF-8", DBSETCHARSET);
}
static void my_dblogin_setdb(LOGINREC* login, char* dbname) {
DBSETLDBNAME(login, dbname);
}
static void my_setlversion(LOGINREC* login) {
dbsetlversion(login, DBVERSION_72);
}
static long dbproc_addr(DBPROCESS * dbproc) {
return (long) dbproc;
}
*/
import "C"
var connections map[int64]*Conn = make(map[int64]*Conn)
var connectionsMutex sync.Mutex
func getConnection(addr int64) *Conn {
connectionsMutex.Lock()
defer connectionsMutex.Unlock()
return connections[addr]
}
func addConnection(conn *Conn) {
connectionsMutex.Lock()
defer connectionsMutex.Unlock()
connections[conn.addr] = conn
}
func deleteConnection(conn *Conn) {
connectionsMutex.Lock()
defer connectionsMutex.Unlock()
delete(connections, conn.addr)
}
const SYBASE string = "sybase"
//Connection to the database.
type Conn struct {
dbproc *C.DBPROCESS
addr int64
Error string
Message string
messageNums map[int]int
messageMutex sync.RWMutex
errors map[int]string
errorsMutex sync.RWMutex
currentResult *Result
expiresFromPool time.Time
belongsToPool *ConnPool
spParamsCache *ParamsCache
credentials
freetdsVersionGte095 bool
}
func (conn *Conn) addMessage(msg string, msgno int) {
conn.messageMutex.Lock()
defer conn.messageMutex.Unlock()
if len(conn.Message) > 0 {
conn.Message += "\n"
}
conn.Message += msg
if conn.currentResult != nil {
conn.currentResult.Message += msg
}
i := conn.messageNums[msgno]
conn.messageNums[msgno] = i + 1
}
func (conn *Conn) addError(err string, errno int) {
conn.errorsMutex.Lock()
defer conn.errorsMutex.Unlock()
conn.errors[errno] = err
if len(conn.Error) > 0 {
conn.Error += "\n"
}
conn.Error += err
}
//Connect to the database with connection string, returns new connection or error.
//Example:
// conn, err := NewConn("host=myServerA;database=myDataBase;user=myUsername;pwd=myPassword;mirror=myMirror")
//
//Mirror is optional, other params are mandatory.
func NewConn(connStr string) (*Conn, error) {
return connectWithCredentials(NewCredentials(connStr))
}
func connectWithCredentials(crd *credentials) (*Conn, error) {
conn := &Conn{
spParamsCache: NewParamsCache(),
credentials: *crd,
messageNums: make(map[int]int),
errors: make(map[int]string),
}
err := conn.reconnect()
if err != nil {
return nil, err
}
return conn, nil
}
func (conn *Conn) connect() (*Conn, error) {
//log.Printf("freetds connecting to %s@%s.%s", conn.user, conn.host, conn.database)
conn.close()
conn.clearMessages()
dbproc, err := conn.getDbProc()
if err != nil {
return nil, err
}
conn.dbproc = dbproc
conn.addr = int64(C.dbproc_addr(dbproc))
addConnection(conn)
if err := conn.setDefaults(); err != nil {
conn.close()
return nil, err
}
//log.Printf("freetds connected to %s@%s.%s", conn.user, conn.host, conn.database)
return conn, nil
}
//If conn belongs to pool release connection to the pool.
//If not close connection.
func (conn *Conn) Close() {
if conn.belongsToPool == nil {
conn.close()
} else {
conn.belongsToPool.Release(conn)
}
}
func (conn *Conn) close() {
deleteConnection(conn)
if conn.dbproc != nil {
C.dbclose(conn.dbproc)
C.dbexit()
conn.dbproc = nil
conn.addr = 0
}
}
// Remove a pooled connection from it's pool.
func RemoveFromPool(conn *Conn) *Conn {
if conn.belongsToPool != nil {
conn.belongsToPool.Remove(conn)
}
return conn
}
//ensure only one getDbProc at a time
var getDbProcMutex = &sync.Mutex{}
func (conn *Conn) getDbProc() (*C.DBPROCESS, error) {
getDbProcMutex.Lock()
defer getDbProcMutex.Unlock()
erc := C.dbinit()
if erc == C.FAIL {
return nil, errors.New("cannot allocate an array of TDS_MAX_CONN TDSSOCKET pointers")
}
login := C.dblogin()
if login == nil {
return nil, errors.New("unable to allocate login structure")
}
cuser := C.CString(conn.user)
defer C.free(unsafe.Pointer(cuser))
cpwd := C.CString(conn.pwd)
defer C.free(unsafe.Pointer(cpwd))
C.my_dblogin(login, cuser, cpwd)
// If a database name is specified in the connection string,
// add the DB name to the login packet.
// Needed for Azure SQL Database, which does not support the USE command
// Supported by FreeTDS 0.91 and later
if len(conn.database) > 0 {
cdatabase := C.CString(conn.database)
defer C.free(unsafe.Pointer(cdatabase))
C.my_dblogin_setdb(login, cdatabase)
}
// Added for Sybase compatibility mode
// Version cannot be set to 7.2
// Allowing version to be set inside freetds
if conn.credentials.compatibility != SYBASE {
C.my_setlversion(login)
}
chost := C.CString(conn.host)
defer C.free(unsafe.Pointer(chost))
dbproc := C.dbopen(login, chost)
if dbproc == nil {
return nil, dbProcError("dbopen error")
}
conn.readFreeTdsVersion()
return dbproc, nil
}
func (conn *Conn) readFreeTdsVersion() {
dbVersion := C.GoString(C.dbversion())
freeTdsVersion := parseFreeTdsVersion(dbVersion)
conn.setFreetdsVersionGte095(freeTdsVersion)
}
func dbProcError(msg string) error {
return fmt.Errorf("%s\n%s\n%s", msg, lastError, lastMessage)
}
//Change database.
func (conn *Conn) DbUse() error {
if len(conn.database) > 0 {
cdatabase := C.CString(conn.database)
defer C.free(unsafe.Pointer(cdatabase))
erc := C.dbuse(conn.dbproc, cdatabase)
if erc == C.FAIL {
return errors.New(fmt.Sprintf("unable to use database %s", conn.database))
}
}
return nil
}
func (conn *Conn) clearMessages() {
conn.messageMutex.Lock()
conn.errorsMutex.Lock()
conn.Error = ""
conn.errors = make(map[int]string)
conn.Message = ""
conn.messageNums = make(map[int]int)
conn.errorsMutex.Lock()
conn.messageMutex.Unlock()
}
//Returns the number of occurances of a supplied FreeTDS message number.
func (conn *Conn) HasMessageNumber(msgno int) int {
conn.messageMutex.RLock()
count := conn.messageNums[msgno]
conn.messageMutex.RUnlock()
return count
}
//Returns the error string for a supplied FreeTDS error number.
//if the error has not occurred then an empty string and false is returned.
func (conn *Conn) HasErrorNumber(errno int) (string, bool) {
conn.errorsMutex.RLock()
err, found := conn.errors[errno]
conn.errorsMutex.RUnlock()
return err, found
}
//Execute sql query.
func (conn *Conn) Exec(sql string) ([]*Result, error) {
results, err := conn.exec(sql)
if err != nil && (conn.isDead() || conn.isMirrorSlave()) {
if err := conn.reconnect(); err != nil {
return nil, err
}
results, err = conn.exec(sql)
}
return results, err
}
//Reconnect to the database, cleaning closing the existing connection
//and switching to a Mirror Database if necessary.
func (conn *Conn) reconnect() error {
var err error
for i := 0; i < 2; i++ {
if conn.isMirrorMessage() {
conn.switchMirror()
}
_, err = conn.connect()
}
return err
}
func (conn *Conn) mirrorDefined() bool {
return len(conn.mirrorHost) > 0
}
func (conn *Conn) isMirrorSlave() bool {
if conn.isMirrorMessage() {
return true
}
if defined, active, isMaster, err := conn.MirrorStatus(); err == nil {
return defined && active && !isMaster
}
return false
}
func (conn *Conn) isMirrorMessage() bool {
return strings.Contains(conn.Message, "It is acting as a mirror database") ||
strings.Contains(conn.Message, "It is in the middle of a restore")
}
func (conn *Conn) switchMirror() {
if !conn.mirrorDefined() {
return
}
tmp := conn.host
conn.host = conn.mirrorHost
conn.mirrorHost = tmp
}
func (conn *Conn) exec(sql string) ([]*Result, error) {
conn.clearMessages()
cmd := C.CString(sql)
defer C.free(unsafe.Pointer(cmd))
if C.dbcmd(conn.dbproc, cmd) == C.FAIL {
return nil, conn.raiseError("dbcmd failed")
}
if C.dbsqlexec(conn.dbproc) == C.FAIL {
return nil, conn.raiseError("dbsqlexec failed")
}
return conn.fetchResults()
}
func (conn *Conn) isDead() bool {
if conn.dbproc == nil {
return true
}
return C.dbdead(conn.dbproc) == C.TRUE
}
func (conn *Conn) isLive() bool {
results, err := conn.exec("select 1")
if err != nil {
return false
}
if results != nil {
if results[0].Rows[0][0].(int32) == 1 {
return true
}
}
return false
}
//Begin database transaction.
func (conn *Conn) Begin() error {
_, err := conn.Exec("begin transaction")
return err
}
//Commit database transaction.
func (conn *Conn) Commit() error {
_, err := conn.Exec("commit transaction")
return err
}
//Rollback database transaction.
func (conn *Conn) Rollback() error {
_, err := conn.Exec("if @@trancount > 0 rollback transaction")
return err
}
//Query database and return first column in the first row as result.
func (conn *Conn) SelectValue(sql string) (interface{}, error) {
results, err := conn.Exec(sql)
if err != nil || results == nil {
return nil, conn.raise(err)
}
if len(results[0].Rows) == 0 {
return nil, errors.New("No rows in result.")
}
return results[0].Rows[0][0], nil
}
//Checking database mirroring status:
// isDefined - is mirror defined (mirror parametar passed in connection string)
// isActive - is mirroring active for this database
// isMaster - is the current host master for this database
//Returns error if could not execute query to get current mirroring status.
func (conn *Conn) MirrorStatus() (bool, bool, bool, error) {
if !conn.mirrorDefined() {
return false, false, false, nil
}
rst, err := conn.exec(fmt.Sprintf(`
SELECT
case when mirroring_guid is not null then 1 else 0 end mirroring_active,
case when mirroring_role = 2 then 0 else 1 end is_master,
mirroring_state, mirroring_state_desc, mirroring_role, mirroring_role_desc,
database_id,
DB_NAME(database_id) database_name
FROM sys.database_mirroring
WHERE DB_NAME(database_id)='%s'
`, conn.database))
if err != nil {
return true, false, false, err
}
var active, isMaster bool
rst[0].Next()
err = rst[0].Scan(&active, &isMaster)
return true, active, isMaster, err
}
func (conn *Conn) setDefaults() error {
var err error
// Adding check for Sybase compatiblity mode
// These connection settings below do not
// function with Sybase ASE
if conn.credentials.compatibility != SYBASE {
//defaults copied from .Net Driver
_, err = conn.exec(`
set quoted_identifier on
set ansi_warnings on
set ansi_padding on
set concat_null_yields_null on
`)
if err != nil {
return err
}
}
if t := conn.credentials.lockTimeout; t > 0 {
_, err = conn.exec(fmt.Sprintf("set lock_timeout %d", t))
}
return err
}
func (conn *Conn) setFreetdsVersionGte095(freeTdsVersion []int) {
//log.Printf("version %v", conn.freeTdsVersion)
conn.freetdsVersionGte095 = false
if len(freeTdsVersion) >= 2 {
if freeTdsVersion[0] > 0 ||
freeTdsVersion[0] == 0 && freeTdsVersion[1] >= 95 {
conn.freetdsVersionGte095 = true
}
}
}
func parseFreeTdsVersion(dbVersion string) []int {
rxFreeTdsVersion := regexp.MustCompile(`v(\d+).(\d+).(\d+)`)
//log.Println("FreeTDS Version: ", dbVersion)
freeTdsVersion := make([]int, 0)
versionMatch := rxFreeTdsVersion.FindStringSubmatch(dbVersion)
if len(versionMatch) == 4 {
for v, ver := range versionMatch {
if v > 0 {
if num, err := strconv.Atoi(ver); err == nil {
freeTdsVersion = append(freeTdsVersion, num)
}
}
}
}
return freeTdsVersion
}