std.parallelism: How to wait all tasks finished?

[Cooler]

On Thursday, 6 February 2014 at 14:42:57 UTC, Cooler wrote:
> On Thursday, 6 February 2014 at 11:30:17 UTC, Andrea Fontana 
> wrote:
>> On Wednesday, 5 February 2014 at 15:38:14 UTC, Cooler wrote:
>>> On Tuesday, 4 February 2014 at 03:26:04 UTC, Dan Killebrew 
>>> wrote:
>>>>>> It seems to me that worker threads will continue as long 
>>>>>> as the queue isn't empty. So if a task adds another task 
>>>>>> to the pool, some worker will process the newly enqueued 
>>>>>> task.
>>>>>
>>>>> No. After taskPool.finish() no way to add new tasks to the 
>>>>> queue. taskPool.put will not add new tasks.
>>>>
>>>> Then perhaps you need to create a new TaskPool (and make 
>>>> sure that workers add their tasks to the correct task pool), 
>>>> so that you can wait on the first task pool, then wait on 
>>>> the second task pool, etc.
>>>>
>>>> auto phase1 = new TaskPool();
>>>> //make sure all new tasks are added to phase1
>>>> phase1.finish(true);
>>>>
>>>> auto phase2 = new TaskPool();
>>>> //make sure all new tasks are added to phase2
>>>> phase2.finish(true);
>>>
>>> Will not help. I don't know beforehand what tasks will be
>>> created. procData is recursive and it decides create new task 
>>> or
>>> not.
>>
>>
>> Something like this? (not tested...)
>>
>> shared bool more = true;
>> ...
>> ...
>> ...
>>
>> void procData(){
>>  if(...)
>>  {
>>    taskPool.put(task(&procData));
>>    more = true;
>>  }
>> }
>>
>> while(true)
>> {
>>   taskPool.finish(true);
>>   if (!more) break;
>>   else more = false;
>> }
>
> It is closer, but after taskPool.finish() all tries to 
> taskPool.put() will be rejected. Let's me clear example.
>
> import std.stdio, std.parallelism, core.thread;
>
> shared int i;
>
> void procData(){
>   synchronized ++i;
>   if(i >= 100)
>     return;
>   foreach(i; 0 .. 100)
>     taskPool.put(task(&procData)); // New tasks will be 
> rejected after
>                                    // taskPool.finish()
> }
>
> void main(){
>   taskPool.put(task(&procData));
>   Thread.sleep(1.msecs); // The final output of "i" depends on 
> duration here
>   taskPool.finish(true);
>   writefln("i = %s", i);
> }
>
> In the example above the total number of tasks executed depends 
> on sleep duration.

Forgot to say - I know how to solve the topic problem. My
question is "What is the BEST way?".
One of my idea - may be introduce new function, named for example
"wait", that will block until there are working tasks?