Hmm,
If you never remove the entries in the hashtable
(what you seem to do with the dataTables)
you can simplify it like...
Hashtable ht = new Hashtable();
Hashtable locks = new Hashtable();
private object GetLockObject( HashKey key)
{
object singleLock = locks[key];
if ( singleLock == null)
{
lock( locks.SynRoot)
{
singleLock = locks[key];
if ( singleLock == null)
{
singleLock = new object();
locks[key] = singleLock;
}
}
}
return singleLock;
}
public DataTable GetList( int a, int b, int c)
{
// lookup the dataTable
HashKey key = new HashKey( a, b, c);
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( GetLockObject( key))
{
dt = (DataTable)ht[key];
if ( dt == null)
{
// insert new DataTable
dt = GetListLong(a, b, c);
ht[key] = dt;
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( GetLockObject( key))
{
dt = (DataTable)ht[key];
if ( Expired( dt))
{
// insert updated DataTable
dt = GetListLong(a, b, c);
ht[key] = dt;
}
}
}
return dt;
}
HTH
// Ryan
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