Hi Ryan, This looks better than my original suggestion - however, this doesn't allow for different combinations of parameters to be called in parallel: this database call could take a few seconds, and the results depending on the parameters will be different. Perhaps I need a hashtable of lock objects? ;-)
Best wishes James > -----Original Message----- > From: Unmoderated discussion of advanced .NET topics. > [mailto:[EMAIL PROTECTED] On Behalf Of Heath Ryan > Sent: 22 July 2004 10:10 > To: [EMAIL PROTECTED] > Subject: Re: [ADVANCED-DOTNET] Multithreaded hash table access > > Hi James, > > the synchronized Hashtable only syncs the hashTable to sync > also the db access, try this one... > > Hashtable ht = new Hashtable(); > > public DataTable GetList( int a, int b, int c) { > // lookup the dataTable > DataTable dt = (DataTable)ht[key]; > > if ( dt == null) > { > // since our last check > // the dataTable might be put already > // by another thread, so lock and lookup again > lock( ht.SynRoot) > { > dt = (DataTable)ht[key]; > if ( dt == null) > { > // insert new DataTable > dt = GetListLong(a, b, c); > ht[key] = dt; > // finished get out! > return dt; > } > } > } > > // dataTable exists, but is it still valid? > if ( Expired( dt)) > { > // since our last check > // an updated dataTable might be put already > // by another thread, so lock and lookup again > lock( ht.SynRoot) > { > dt = (DataTable)ht[key]; > if ( Expired( dt)) > { > // insert updated DataTable > dt = GetListLong(a, b, c); > ht[key] = dt; > } > } > } > > return dt; > } > > HTH > // Ryan =================================== This list is hosted by DevelopMentorŪ http://www.develop.com Some .NET courses you may be interested in: NEW! Guerrilla ASP.NET, 17 May 2004, in Los Angeles http://www.develop.com/courses/gaspdotnetls View archives and manage your subscription(s) at http://discuss.develop.com
