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From "Antony Paul" <antonypau...@hotmail.com>
Subject Re: [OT] Synchronising database access
Date Fri, 21 Nov 2003 12:18:03 GMT
thanks for the reply
synchrosing servlet code dont work ?

Antony Paul

----- Original Message -----
From: "Peter Guyatt" <pguyatt@telesoft-technologies.com>
To: "Tomcat Users List" <tomcat-user@jakarta.apache.org>
Sent: Friday, November 21, 2003 5:28 PM
Subject: RE: [OT] Synchronising database access


> Hi There,
>
> Use a singleton class to manage the database transactions.
>
> Then implement a owner mechanism. E.g.
>
> class DbTxMgr {
>
> String owner = null;
>
> public synchronized boolean lockMgr (String threadId) {
> if (owner == null) {
> owner = threadId;
> return true;
> } else {
> if (owner.equals(threadId)) {
> return true
> }
> return false;
> }
> }
>
> public synchronized void releaseMgr (String threadId) {
> if (owner != null) {
> if (owner.equals(threadId)) {
> owner = null;
> }
> }
> }
>
> public synchronized boolean insert (String statement, String threadId) {
> if (owner == null) {
> owner = threadId;
> }
> if (owner.equals(threadId)) {
> file://do the transaction
> }
> }
> }
>
> your code
>
> class tester {
> file://name of your thread
> Thread t = new Thread("testerThread")
> ...
>
> if (lockMgr(t.getName())) {
> file://do database code
> }
> lockMgr.releaseLock(t.getName());
>
> }
>
> This way olny the owner of the lock can perform transactions and all other
> threads must wait for the lock to be released
>
> Thanks
>
> Pete
>
>
> -----Original Message-----
> From: Antony Paul [mailto:antonypaul24@hotmail.com]
> Sent: 21 November 2003 11:51
> To: Tomcat Users List
> Subject: [OT] Synchronising database access
>
>
> Hi,
>     I want to synchronise all database access. There are lots of
situations
> where first first a select query is performed to get the results and then
> insert/update data. I dont want to implement row level locking or
optimistic
> locking. I just want to synchronise the whole process. Only after a thread
> completes the entire process other threads can execute the code. How to do
> it. Do I have to synchronise on Connection or on this or implement
> SingleThreadModel. I also want to know how much extra time a synchronised
> block requires than an unsynchronised block.
>
> Antony Paul.
>
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