I’m trying to create a UI thread to do constant background work, but I’m having some design problems.

The thread needs to fetch records from a database. do some processing on each record and, when there are no more records, sleep for 1 minute before check the database again. The process will be controlled with thread messages (to start, pause, query…).

My problem is where should I put the processing work. I need it to be responsive between cycles, where the process waits for 1 minute, so I can stop it in that period. My only idea is using OnIdle to do the work.
But then, how should I make it real idle when waiting for 1 minute?

Could anyone give some hints on what is the way to go?

Scott McPhillips [VC++ MVP]

You can’t use Sleep and still be responsive to messages. Instead of using Sleep you could use SetTimer in the main thread and post a message to the thread, or SetTimer to a hidden window within the thread, or you could use a loop within the thread and use MsgWaitForMultipleObjects within the loop.

MsgWaitForMultipleObjects has a timeout parameter that gives you the sleep period, but it also returns early if a message or event comes along.

Almond and Joseph M. Newcomer [MVP]

I would be strongly disinclined to use MsgWaitForMultipleObjects. You don’t gain anything by using it over using WM_TIMER, and it requires that you have to write your own message pump, always a dangerous proposition.

BUT, SOME MORE DISCUSSION ABOUT THE UI THREAD AND WORKER THREAD…

Almond

Do not use UI threads for this kind of thing.

David

I would create a worker thread (not a UI thread) unless you need a UI thread for some specific purpose not apparent in this description. The worker thread would do it’s work and then do a WaitForSingleObject() with a timeout of 1 minute (60000 ms), which causes WaitForSingleObject() to return when either the main thread sets an event for starting, pausing, querying, etc. or the 1 minute has elapsed. If you need separate events each for starting, pausing, querying, etc. use WaitForMultipleObjects() instead of WaitForSingleObject().

Joseph M. Newcomer [MVP]

UI threads are actually ideal for this sort of thing. Don’t be confused by the phrase ‘UI’ meaning something with windows; think of it as “a thread with a built-in queuing mechanism”. They’re really very good for things that require timed events as the OP described.

There are some advantages to UI threads; for example, a UI thread has a built-in queue.
Also, for some kinds of interfacing require a message pump to deal with event handling. I don’t do databases so I don’t know if databases have this requirement, but there are On-Anything handlers involved in the database interface, then a UI thread is required.

I’m trying to create a UI thread to do constant background work, but I’m having some design problems.

The thread needs to fetch records from a database. do some processing on each record and, when there are no more records, sleep for 1 minute before check the database again. The process will be controlled with thread messages (to start, pause, query…).

My problem is where should I put the processing work. I need it to be
responsive between cycles, where the process waits for 1 minute, so I
can stop it in that period. My only idea is using OnIdle to do the work.
  But then, how should I make it real idle when waiting for 1 minute?

Could anyone give some hints on what is the way to go?

Scott McPhillips [VC++ MVP]

You can’t use Sleep and still be responsive to messages.  Instead of using Sleep you could use SetTimer in the main thread and post a message to the thread, or SetTimer to a hidden window within the thread, or you could use a loop within the thread and use MsgWaitForMultipleObjects within the loop.

MsgWaitForMultipleObjects has a timeout parameter that gives you the sleep period, but it also returns early if a message or event comes along.

Almond and Joseph M. Newcomer [MVP]

I would be strongly disinclined to use MsgWaitForMultipleObjects.  You don’t gain anything by using it over using WM_TIMER, and it requires that you have to write your own message pump, always a dangerous proposition.

BUT, SOME MORE DISCUSSION ABOUT THE UI THREAD AND WORKER THREAD…

Almond

Do not use UI threads for this kind of thing.

David

I would create a worker thread (not a UI thread) unless you need a UI thread for some specific purpose not apparent in this description.  The worker thread would do it’s work and then do a WaitForSingleObject() with a timeout of 1 minute (60000 ms), which causes WaitForSingleObject() to return when either the main thread sets an event for starting, pausing, querying, etc. or the 1 minute has elapsed.  If you need separate events each for starting, pausing, querying, etc. use WaitForMultipleObjects() instead of WaitForSingleObject().

Joseph M. Newcomer [MVP]

UI threads are actually ideal for this sort of thing.  Don’t be confused by the phrase ‘UI’ meaning something with windows; think of it as “a thread with a built-in queuing mechanism”.  They’re really very good for things that require timed events as the OP described.

There are some advantages to UI threads; for example, a UI thread has a built-in queue.
Also, for some kinds of interfacing require a message pump to deal with event handling.  I don’t do databases so I don’t know if databases have this requirement, but there are On-Anything handlers involved in the database interface, then a UI thread is required.

How to read the sectors of physical drive under win32?

The API ReadFile is most useful function, and with it, you can read the physical sectors directly.

Here is a sample function, BOOL ReadSectors(…)

The WMI redist package is not always available on user’s system, for example, Windows NT4 and Windows 95/98.  And the Volume Serial Number of HDD can be easily changed while the CPU ID is not always available.

As Walter Wang said, the manufacturer of harddisk stored a unique Firmware Serial Number in the harddisk when it’s built. It doesn’t change with Operating System Changes or HDD formatting. So I should serve your purpose.

For source code example on how to retrieve this HDD Firmware Serial Number using DeviceIoControl, you can refer to following this article. It support IDE, SATA and SCSI drive type.

http://www.winsim.com/diskid32/diskid32.html

Local download: diskid32.zipp
Simple output of diskid32:

Primary Controller – Master drive

Drive Model Number________________: ST380011A
Drive Serial Number_______________: 3JV6TBXW
Drive Controller Revision Number__: 3.04
Controller Buffer Size on Drive___: 2097152 bytes
Drive Type________________________: Fixed
Drive Size________________________: 76264796672 bytes

Trying to read the drive IDs using the SCSI back door

Primary Controller – Master drive

Drive Model Number________________: ST380011A
Drive Serial Number_______________: 3JV6TBXW
Drive Controller Revision Number__: 3.04
Controller Buffer Size on Drive___: 2097152 bytes
Drive Type________________________: Fixed
Drive Size________________________: 76264796672 bytes

Trying to read the drive IDs using physical access wi

**** STORAGE_DEVICE_DESCRIPTOR for drive 0 ****
Vendor Id = (
Product Id = ST380011A
Product Revision = 3.04
Serial Number = 3JV6TBXW

Hard Drive Serial Number__________: 3JV6TBXW
Hard Drive Model Number___________: ST380011A
Computer ID_______________________: 652190462
MAC Address: 00-FF-5B-FE-6B-20
MAC Address: 00-0C-76-74-DA-50