1 files changed, 113 insertions, 6 deletions

diff --git a/zen/thread.h b/zen/thread.h
index 4598ea99..ba9a46e2 100644
--- a/zen/thread.h
+++ b/zen/thread.h
@@ -8,6 +8,8 @@
 #define BOOST_THREAD_WRAP_H
 
 //temporary solution until C++11 thread becomes fully available
+#include <vector>
+#include <memory>
 
 #ifdef __MINGW32__
 #pragma GCC diagnostic push
@@ -39,12 +41,31 @@ Example:
 template <class Function>
 auto async(Function fun) -> boost::unique_future<decltype(fun())>;
 
+//wait for all with a time limit: return true if *all* results are available!
 template<class InputIterator, class Duration>
-void wait_for_all_timed(InputIterator first, InputIterator last, const Duration& wait_duration);
+bool wait_for_all_timed(InputIterator first, InputIterator last, const Duration& wait_duration);
 
+//wait until first job is successful or all failed
+template <class T>
+class RunUntilFirstHit
+{
+public:
+    RunUntilFirstHit();
+
+    template <class Fun>
+    void addJob(Fun f); //f must return a std::unique_ptr<T> containing a value if successful
 
+    template <class Duration>
+    bool timedWait(const Duration& duration) const; //true: "get()" is ready, false: time elapsed
 
+    //return first value or none if all jobs failed; blocks until result is ready!
+    std::unique_ptr<T> get() const; //must be called only once!
 
+private:
+    class AsyncResult;
+    std::vector<boost::thread> workload;
+    std::shared_ptr<AsyncResult> result;
+};
 
 
 
@@ -72,21 +93,107 @@ auto async2(Function fun) -> boost::unique_future<T> //workaround VS2010 bug: bo
 }
 
 
-template <class Function> inline auto async(Function fun) -> boost::unique_future<decltype(fun())> { return async2<decltype(fun())>(fun); }
+template <class Function> inline
+auto async(Function fun) -> boost::unique_future<decltype(fun())> { return async2<decltype(fun())>(fun); }
 
 
 template<class InputIterator, class Duration> inline
-void wait_for_all_timed(InputIterator first, InputIterator last, const Duration& wait_duration)
+bool wait_for_all_timed(InputIterator first, InputIterator last, const Duration& wait_duration)
 {
     const boost::system_time endTime = boost::get_system_time() + wait_duration;
     while (first != last)
     {
-        first->timed_wait_until(endTime);
-        if (boost::get_system_time() >= endTime)
-            return;
+        if (!first->timed_wait_until(endTime))
+            return false; //time elapsed
         ++first;
     }
+    return true;
 }
+
+
+template <class T>
+class RunUntilFirstHit<T>::AsyncResult
+{
+public:
+    AsyncResult() :
+#ifndef NDEBUG
+        returnedResult(false),
+#endif
+        jobsFinished(0) {}
+
+    //context: worker threads
+    void reportFinished(std::unique_ptr<T>&& result)
+    {
+        {
+            boost::unique_lock<boost::mutex> dummy(lockResult);
+            ++jobsFinished;
+            if (!result_)
+                result_ = std::move(result);
+        }
+        conditionJobDone.notify_one();
+        //condition handling, see: http://www.boost.org/doc/libs/1_43_0/doc/html/thread/synchronization.html#thread.synchronization.condvar_ref
+    }
+
+    //context: main thread
+    template <class Duration>
+    bool waitForResult(size_t jobsTotal, const Duration& duration)
+    {
+        boost::unique_lock<boost::mutex> dummy(lockResult);
+        return conditionJobDone.timed_wait(dummy, duration, [&] { return this->jobDone(jobsTotal); });
+        //use timed_wait predicate if exitting before condition is reached: http://www.boost.org/doc/libs/1_49_0/doc/html/thread/synchronization.html#thread.synchronization.condvar_ref.condition_variable.timed_wait_rel
+    }
+
+    std::unique_ptr<T> getResult(size_t jobsTotal)
+    {
+        boost::unique_lock<boost::mutex> dummy(lockResult);
+
+        while (!jobDone(jobsTotal))
+            conditionJobDone.timed_wait(dummy, boost::posix_time::milliseconds(50)); //interruption point!
+
+#ifndef NDEBUG
+        assert(!returnedResult);
+        returnedResult = true;
+#endif
+        return std::move(result_);
+    }
+
+private:
+    bool jobDone(size_t jobsTotal) const { return result_ || (jobsFinished >= jobsTotal); } //call while locked!
+#ifndef NDEBUG
+    bool returnedResult;
+#endif
+
+    boost::mutex lockResult;
+    size_t jobsFinished;        //
+    std::unique_ptr<T> result_; //our condition is: "have result" or "jobsFinished == jobsTotal"
+    boost::condition_variable conditionJobDone;
+};
+
+
+
+template <class T> inline
+RunUntilFirstHit<T>::RunUntilFirstHit() : result(std::make_shared<AsyncResult>()) {}
+
+
+template <class T>
+template <class Fun> inline
+void RunUntilFirstHit<T>::addJob(Fun f) //f must return a std::unique_ptr<T> containing a value on success
+{
+    auto result2 = result; //VC11: this is ridiculous!!!
+    workload.push_back(boost::thread([result2, f]
+    {
+        result2->reportFinished(f());
+    }));
+}
+
+
+template <class T>
+template <class Duration> inline
+bool RunUntilFirstHit<T>::timedWait(const Duration& duration) const { return result->waitForResult(workload.size(), duration); }
+
+
+template <class T> inline
+std::unique_ptr<T> RunUntilFirstHit<T>::get() const { return result->getResult(workload.size()); }
 }
 
 #endif //BOOST_THREAD_WRAP_H