improve comments

git-svn-id: svn+ssh://svn.gna.org/svn/gnustep/libs/sqlclient/trunk@37891 72102866-910b-0410-8b05-ffd578937521

SQLClient.h

@@ -1238,7 +1238,11 @@ SQLCLIENT_PRIVATE
 
 /**
  * The default implementation calls NSLogv to log a debug message.<br />
- * Override this in a category to provide more sophisticated logging.
+ * Override this in a category to provide more sophisticated logging.<br />
+ * Do NOT override with code which can be slow or which calls (directly
+ * or indirectly) any SQLCLient methods, since this method will be used
+ * inside locked regions of the SQLClient code and you could cause
+ * deadlocks or long delays to other threads using the class.
  */
 - (void) debug: (NSString*)fmt, ...;
 

SQLClient.m

@@ -1403,7 +1403,7 @@ static unsigned int	maxConnections = 8;
 
   [clientsMapLock lock];
   existing = (SQLClient*)NSMapGet(clientsMap, reference);
-  if (existing == nil)
+  if (nil == existing)
     {
       lock = [NSRecursiveLock new];	// Ensure thread-safety.
       [self setDebugging: [[self class] debugging]];
@@ -2194,11 +2194,15 @@ static unsigned int	maxConnections = 8;
  */
 - (void) _configure: (NSNotification*)n
 {
-  NSDictionary	*o = [n object];
+  NSDictionary	*o;
   NSDictionary	*d;
   NSString	*s;
   Class		c;
 
+  [lock lock];
+  NS_DURING
+    {
+      o = [n object];
       /*
        * get dictionary containing config info for this client by name.
        */
@@ -2330,6 +2334,14 @@ static unsigned int	maxConnections = 8;
             }
         }
       [self setPassword: s];
+    }
+  NS_HANDLER
+    {
+      [lock unlock];
+      [localException raise];
+    }
+  NS_ENDHANDLER
+  [lock unlock];
 }
 
 /** Internal method to populate the cache with the result of a query.