Handle cache in diskOperation

[huntrax11]

would you like to handle cache in disk operation?
You know some code like above-

• (NSData_)dataForKey:(NSString_)key {
  if([self hasCacheForKey:key]) {
  return [NSData dataWithContentsOfFile:cachePathForKey(key) options:0 error:NULL];
  } else {
  for(NSInvocationOperation* operation in [diskOperationQueue operations]){
  NSInvocation *invocation=[operation invocation];
  NSString *path=nil;
  NSData *data=nil;
  [invocation getArgument:&path atIndex:3];
  if([path hasSuffix:key]){
  [invocation getArgument:&data atIndex:2];
  return data;
  }
  }
  return nil;
  }
  }