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Re: question?






Am 08.01.2015 um 16:01 schrieb bruce:
hey.

within php (or any other language)

is there a way to create the mysql sql, and execute the sql, where the
process can "wait" until the network connection for the mysql
command/process is actually valid?

IE (phpesque)
$pdo=new pdo()
sql = "select * from foo where a=:a"
$s=$pdo->prepare($sql)
$s->bind("a",$one)
$s->execute()

The issue we're seeing, is that the network (it's all wifi) is really
bad.. and the app machine, might not have a connection to the db box.

We're wondering if there's a way to simply have mysql/php detect when
a valid connection is there, and then proceed.

We've thought about the try/catch process, any others?

snippets from our db-layer to get an idea

* everytime a error happens the reconnect method is triggered
* reconnect tries 300 times with a small sleep to connect again
* after it returns the last query is fired again

works that way for around 8 years now and we can restart mysqld at every random moment without lose a single web request
________________________________________


if(!in_array(@mysqli_errno($this->conn), array_keys($this->ignored_errors)))
       {
        $this->reconnect();
        $fehler = 0;
        switch($unbuffered)
        {
case true: $result = @mysqli_query($this->conn, $sql, MYSQLI_USE_RESULT) or $fehler = 1; break; default: $result = @mysqli_query($this->conn, $sql, MYSQLI_STORE_RESULT) or $fehler = 1; break;
        }
       }


  public function reconnect()
  {
   $this->disconnect();
   $this->connect($this->persistent);
  }


      if(!$rw)
      {
       for($retry=1; $retry<=300; $retry++)
       {
        /** Initialisieren */
        $this->conn = @mysqli_init();
        /** SSL-Encryption wenn aktiviert und TCP */
        if($this->ssl && $this->host != 'localhost')
        {
/** Wenn kein Zertifikat angegeben ist Dummy-Eintrag fuer Standard-Handshake da sonst keine Verschluesselung etabliert wird */
         if($this->ssl_crt === '')
         {
          $this->ssl_crt = 'dummy.crt';
         }
         /** SSL aktivieren */
$this->conn->ssl_set($this->ssl_key, $this->ssl_crt, $this->ssl_ca, NULL, 'ECDHE-RSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-SHA256:ECDHE-RSA-AES128-SHA:DHE-RSA-AES128-GCM-SHA256:DHE-RSA-AES128-SHA256:DHE-RSA-AES128-SHA:DHE-RSA-AES256-SHA:RSA-AES256-SHA');
        }
        /** Verbindung herstellen */
        switch($persistent)
        {
case 1: $rw = @mysqli_real_connect($this->conn, 'p:' . $this->host, $this->user, $this->pwd, $this->db, $this->port, '', $flags); break; default: $rw = @mysqli_real_connect($this->conn, $this->host, $this->user, $this->pwd, $this->db, $this->port, '', $flags); break;
        }
/** Wenn Server wieder verfuegbar Verbindung erneut trennen und aufbauen um Fehlern waehrend des Initialisieren des Dienstes aus dem Weg zu gehen */
        if($rw)
        {
         /** Initialisieren */
         $this->conn = @mysqli_init();
         /** SSL-Encryption wenn aktiviert und TCP */
         if($this->ssl && $this->host != 'localhost')
         {
/** Wenn kein Zertifikat angegeben ist Dummy-Eintrag fuer Standard-Handshake da sonst keine Verschluesselung etabliert wird */
          if($this->ssl_crt === '')
          {
           $this->ssl_crt = 'dummy.crt';
          }
          /** SSL aktivieren */
$this->conn->ssl_set($this->ssl_key, $this->ssl_crt, $this->ssl_ca, NULL, 'ECDHE-RSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-SHA256:ECDHE-RSA-AES128-SHA:DHE-RSA-AES128-GCM-SHA256:DHE-RSA-AES128-SHA256:DHE-RSA-AES128-SHA:DHE-RSA-AES256-SHA:RSA-AES256-SHA');
         }
         /** Verbindung herstellen */
         switch($persistent)
         {
case 1: $rw = @mysqli_real_connect($this->conn, 'p:' . $this->host, $this->user, $this->pwd, $this->db, $this->port, '', $flags); break; default: $rw = @mysqli_real_connect($this->conn, $this->host, $this->user, $this->pwd, $this->db, $this->port, '', $flags); break;
         }
         break;
        }
        usleep(50000);
       }
/** Es konnte trotz mehrmaligem Versuch keine Verbindung hergestellt werden */
       if(!$rw)
       {
        $host_resolved  = @gethostbyaddr($this->host);
        if(!$host_resolved)
        {
         $host_resolved = $this->host;
        }
        $this->conn = 0;
$this->error('Verbindung zu Datenbank-Server <span style="white-space:nowrap;">&quot;' . trim($host_resolved . ':' . $this->port . ' ' . $this->db) . '&quot;</span> konnte nicht hergestellt werden.<br /><br />' . mysqli_connect_error());
       }
      }

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