Explicit resource locking in sqlserver

I had a problem where I need explicit locking of resources in the SQL SERVER.
When sp1 run I need to prevent sp2 to run in parallel.
The stored procedures handle deferent DataBase resources so the transaction locking can’t help in this case . 

I have found the following article that helped me solve the problem:

http://www.mssqltips.com/sqlservertip/3202/prevent-multiple-users-from-running-the-same-sql-server-stored-procedure-at-the-same-time/?utm_source=dailynewsletter&utm_medium=email&utm_content=headline&utm_campaign=20140414

The the solution is based on the  sp_getapplock command.

Exec @rc = sp_getapplock @Resource='myLock' -- the resource to be locked can be any mutex name

         , @LockMode='Exclusive'  -- Type of lock

         , @LockOwner='Transaction' -- Transaction or Session

         , @LockTimeout = 15000 -- timeout in milliseconds, 15 seconds

Committing or aborting the transaction release the lock.
allow voiding the call to sp_releaseapplock

Don’t forget to check if timeout error occurred after the sp_getapplock has returned.

I although learn from the article to use the :
set @msg= convert(varchar,getdate(), 114) + ' requesting lock'
raiserror (@msg, 0, 1) with nowait

in order to output debug strings while executing a test code.

JCLOUDS blob storage for openstack swift

We use Jclouds blob storage in order to manage the Blobs in our private cload swift blob storage .
The following code demonstrates creating , writing , exploring and reading from swift using jcloud SwiftBlobStore.

package com.gmuav.playwithjcloads;
import java.io.IOException;
import org.jclouds.ContextBuilder;
import org.jclouds.blobstore.BlobStore;
import org.jclouds.blobstore.BlobStoreContext;
import org.jclouds.blobstore.domain.Blob;
import org.jclouds.blobstore.domain.StorageMetadata;
import com.google.common.base.Charsets;
import com.google.common.io.ByteSource;
public class PlayWithSwift {
  
   public static void main(String[] args) throws IOException {
 
    
      String identity = " --- ";
      String credential = " --- ";
      String containerName = "myContainer";
      
       ByteSource payload = ByteSource.wrap("This is the Data as text ".getBytes(Charsets.UTF_8));
     
      BlobStoreContext context = ContextBuilder.newBuilder("swift")
                                               .credentials(identity, credential)
                                               .buildView(BlobStoreContext.class);
      try {
         // Create Container
         BlobStore blobStore = context.getBlobStore();
         blobStore.createContainerInLocation(null, containerName);
         String theBlobName = "myFolder/myData";
    
         Blob blob = blobStore.blobBuilder(theBlobName)
            .payload(payload)
            .contentLength(payload.size())
            .build();
       
         blobStore.putBlob(containerName, blob);
           // List Container
         for (StorageMetadata nextBlob : blobStore.list()) {
            System.out.println("NextBlob:" + nextBlob.getName());
         }
         
         Blob theRetreivedBlob =  blobStore.getBlob(identity, theBlobName);
               
         String theRetValue = new String (((ByteSource)theRetreivedBlob.getPayload()).read() , Charsets.UTF_8);
         
          System.out.println("The blob data  " + theRetValue);
         
         
      } finally {
         context.close();       
      }
   }
}

 

References:
jclouds-examples

Creating attributes in sysfs

The sysfs allow User space kernel space simple communication  .

The code

#include <linux/kobject.h>
#include <linux/string.h>
#include <linux/sysfs.h>
#include <linux/module.h>
#include <linux/init.h>
/*
 * The module demonstrats creating 2 attributes in a subdirectory of sysfs.
 *  ls the /sys/kernel/mykobject  
 */
static int intValue = 0;
static char  TxtBuffer[50];
static ssize_t attr_show(struct kobject *kobj, struct kobj_attribute *attr,
        char *buf)
{
 if (strcmp(attr->attr.name, "TxtBuffer") == 0)
 {
  return sprintf(buf, "%s\n", TxtBuffer);
 }
 
 if (strcmp(attr->attr.name, "intValue") == 0)
 {
  return sprintf(buf, "%d\n", intValue);
 }
 
 return 0;
}
static ssize_t attr_store(struct kobject *kobj, struct kobj_attribute *attr,
         const char *buf, size_t count)
{
 
 if (strcmp(attr->attr.name, "TxtBuffer") == 0)
 {
  strcpy (TxtBuffer, buf);
  return count;
 }
 
 if (strcmp(attr->attr.name, "intValue") == 0)
 {
  int theTmpVar;
  sscanf(buf, "%du", &theTmpVar);
  intValue = theTmpVar;
  return count;
 }
 return 0;
}
static struct kobj_attribute intValue_attribute =
 __ATTR(intValue, 0666, attr_show, attr_store);
 
static struct kobj_attribute TxtBuffer_attribute =
 __ATTR(TxtBuffer, 0666, attr_show, attr_store);
 
static struct attribute *attrs[] = {
 &intValue_attribute.attr,
 &TxtBuffer_attribute.attr,
 NULL, 
};
static struct attribute_group attr_group = {
 .attrs = attrs,
  .name = NULL,   /* we want them in the same directory */
};
static struct kobject *mykobject;
static int mykobject_init(void)
{
 int retval;
 mykobject = kobject_create_and_add("mykobject", kernel_kobj);
 if (!mykobject)
  return -ENOMEM;
 
 retval = sysfs_create_group(mykobject, &attr_group);
 if (retval)
  kobject_put(mykobject);
 return retval;
}
static void mykobject_exit(void)
{
 kobject_put(mykobject);
}
module_init(mykobject_init);
module_exit(mykobject_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Zvika Peer  <zvikapeer@hotmail.com>");

After installing the module using insmod let test it. The module directory is :
ls  /sys/kernel/

Inspecting  the mykobject attributes
zvika@zvika-Linux:~/Learn/Drivers/HelloWorld$ ls  /sys/kernel/mykobject
intValue  TxtBuffer

Inserting Data into the attributes:

zvika@zvika-Linux:~/Learn/Drivers/HelloWorld$ sudo echo "Hello zvika" > /sys/kernel/mykobject/TxtBuffer
zvika@zvika-Linux:~/Learn/Drivers/HelloWorld$ sudo echo 164  > /sys/kernel/mykobject/intValue

Retrieving the data back from the attributes:

zvika@zvika-Linux:~/Learn/Drivers/HelloWorld$ sudo cat  /sys/kernel/mykobject/intValue
164
zvika@zvika-Linux:~/Learn/Drivers/HelloWorld$ sudo cat  /sys/kernel/mykobject/TxtBuffer
Hello zvika

python __get__ magic method

I used the __get__ python magic method in order to implement  explicit conversion of class :
The following example converts a string wrapper class into the string length:

class TheConverter:
    def __init__ (self):
        pass
    def __get__ (self, instance, owner):       
        return len ( instance.mValue)
   
class ToGetConverted:
    def __init__ (self ,pValue ):
        self.mValue = pValue
    LenConvertor = TheConverter()
print (ToGetConverted("Hands Up").LenConvertor)
if __name__ == '__main__':
    pass

The sample returns : 8

References:
magic words

 

Open stack cinder block

I have found the following blog post regarding Open Stack cinder block:
laying-cinder-block-volumes-in-openstack-part-1-the-basics
Cinder allows to attach external  storage volume into the cloud in addition to the instance ephemeral storage

The cinder api can be found here :
cinder api
Allows to create volumes , update volumes , delete volumes , list volume information
Handle snapshots

Map interface design review

Last week I had design review session about Map wrapper interfaces.
The interface is part of a module that allows a programmer to switch map infrastructure implementations within its product transparently  to the logic of the UI layer 

Part of the proposed interface looks something like this :

The goal of the MapSurface interface is to allow adding drawing annotations on the map like routes , spots areas etc.

Prons

1.KISS:
Very simple interface allow the programmer quickly learned how to use it even without documentation and code samples . 

Cons

1.Open close principle violation:
In order to add handling for new widget type for an example a closed curved etc the IMapInterface  should be changed .

2.The interface does not allow me to use the created route in a surface of a map in other window .

 

 

 

Configure netbeans for Php debugging

In order to allow Php debugging on NetBeans IDE 7.4 I did the following steps :

1.Change the php ini file as follow :
[XDebug]
zend_extension = "C:\xampp\php\ext\php_xdebug.dll"
xdebug.profiler_append = 0
xdebug.profiler_enable = 1
xdebug.profiler_enable_trigger = 0
xdebug.profiler_output_dir = "C:\xampp\tmp"
xdebug.profiler_output_name = "cachegrind.out.%t-%s"
xdebug.remote_enable = 1
xdebug.remote_handler = "dbgp"
xdebug.remote_host = "127.0.0.1"
xdebug.trace_output_dir = "C:\xampp\tmp"

The php ini file is located under :
C:\xampp\php\php.ini

2.Make sure that the tools – options  in the netbeans is like this

The project properties :

Restart the xamp apache server .

and walla