1 files changed, 89 insertions, 65 deletions

diff --git a/zen/thread.h b/zen/thread.h
index ed61e06b..ee36f305 100755
--- a/zen/thread.h
+++ b/zen/thread.h
@@ -10,9 +10,9 @@
 #include <thread>
 #include <future>
 #include "scope_guard.h"
-#include "type_traits.h"
+#include "ring_buffer.h"
 #include "optional.h"
-    #include <sys/prctl.h>
+#include "string_tools.h"
 
 
 namespace zen
@@ -23,8 +23,8 @@ class InterruptibleThread
 {
 public:
     InterruptibleThread() {}
-    InterruptibleThread           (InterruptibleThread&& tmp) = default;
-    InterruptibleThread& operator=(InterruptibleThread&& tmp) = default;
+    InterruptibleThread           (InterruptibleThread&&) noexcept = default;
+    InterruptibleThread& operator=(InterruptibleThread&&) noexcept = default;
 
     template <class Function>
     InterruptibleThread(Function&& f);
@@ -46,7 +46,7 @@ public:
 
 private:
     std::thread stdThread_;
-    std::shared_ptr<InterruptionStatus> intStatus_{ std::make_shared<InterruptionStatus>() };
+    std::shared_ptr<InterruptionStatus> intStatus_ = std::make_shared<InterruptionStatus>();
     std::future<void> threadCompleted_;
 };
 
@@ -62,7 +62,9 @@ void interruptibleSleep(const std::chrono::duration<Rep, Period>& relTime); //th
 void setCurrentThreadName(const char* threadName);
 
 uint64_t getThreadId(); //simple integer thread id, unlike boost::thread::id: https://svn.boost.org/trac/boost/ticket/5754
+uint64_t getMainThreadId();
 
+inline bool runningMainThread() { return getThreadId() == getMainThreadId(); }
 //------------------------------------------------------------------------------------------
 
 /*
@@ -118,6 +120,7 @@ class Protected
 public:
     Protected() {}
     Protected(const T& value) : value_(value) {}
+    //Protected(      T&& tmp ) : value_(std::move(tmp)) {} <- wait until needed
 
     template <class Function>
     auto access(Function fun) //-> decltype(fun(std::declval<T&>()))
@@ -140,53 +143,101 @@ template <class Function>
 class ThreadGroup
 {
 public:
-    ThreadGroup(size_t threadCount, const std::string& groupName)
-    {
-        for (size_t i = 0; i < threadCount; ++i)
-            worker_.emplace_back([this, groupName, i, threadCount]
-        {
-            setCurrentThreadName((groupName + "[" + numberTo<std::string>(i + 1) + "/" + numberTo<std::string>(threadCount) + "]").c_str());
-            for (;;)
-                getNextWorkItem()(); //throw ThreadInterruption
-        });
-    }
+    ThreadGroup(size_t threadCountMax, const std::string& groupName) : threadCountMax_(threadCountMax), groupName_(groupName)
+    { if (threadCountMax == 0) throw std::logic_error("Contract violation! " + std::string(__FILE__) + ":" + numberTo<std::string>(__LINE__)); }
+
     ~ThreadGroup()
     {
         for (InterruptibleThread& w : worker_) w.interrupt(); //interrupt all first, then join
-        for (InterruptibleThread& w : worker_) w.join();
+        for (InterruptibleThread& w : worker_) detach_ ? w.detach() : w.join();
     }
 
+    ThreadGroup(ThreadGroup&& tmp) noexcept :
+        worker_        (std::move(tmp.worker_)),
+        workLoad_      (std::move(tmp.workLoad_)),
+        detach_        (tmp.detach_),
+        threadCountMax_(tmp.threadCountMax_),
+        groupName_     (std::move(tmp.groupName_)) { tmp.worker_.clear(); /*just in case: make sure destructor is no-op!*/ }
+
+    ThreadGroup& operator=(ThreadGroup&& tmp) noexcept { swap(tmp); return *this; } //noexcept *required* to support move for reallocations in std::vector and std::swap!!!
+
     //context of controlling thread, non-blocking:
     void run(Function&& wi)
     {
-        assert(!worker_.empty());
+        size_t tasksPending = 0;
         {
-            std::lock_guard<std::mutex> dummy(lockWork_);
-            workItems_.push_back(std::move(wi));
+            std::lock_guard<std::mutex> dummy(workLoad_->lock);
+            workLoad_->tasks.push_back(std::move(wi));
+            tasksPending = ++(workLoad_->tasksPending);
         }
-        conditionNewWork_.notify_all();
+        workLoad_->conditionNewTask.notify_all();
+
+        if (worker_.size() < std::min(tasksPending, threadCountMax_))
+            addWorkerThread();
     }
 
+    //context of controlling thread, blocking:
+    void wait()
+    {
+        std::unique_lock<std::mutex> dummy(workLoad_->lock);
+        workLoad_->conditionTasksDone.wait(dummy, [&tasksPending = workLoad_->tasksPending] { return tasksPending == 0; });
+    }
+
+    void detach() { detach_ = true; } //not expected to also interrupt!
+
 private:
     ThreadGroup           (const ThreadGroup&) = delete;
     ThreadGroup& operator=(const ThreadGroup&) = delete;
 
-    //context of worker threads, blocking:
-    Function getNextWorkItem() //throw ThreadInterruption
+    void addWorkerThread()
     {
-        std::unique_lock<std::mutex> dummy(lockWork_);
+        std::string threadName = groupName_ + '[' + numberTo<std::string>(worker_.size() + 1) + '/' + numberTo<std::string>(threadCountMax_) + ']';
+
+        worker_.emplace_back([wl = workLoad_, threadName = std::move(threadName)] //don't capture "this"! consider detach() and swap()
+        {
+            setCurrentThreadName(threadName.c_str());
+
+            std::unique_lock<std::mutex> dummy(wl->lock);
+            for (;;)
+            {
+                interruptibleWait(wl->conditionNewTask, dummy, [&tasks = wl->tasks] { return !tasks.empty(); }); //throw ThreadInterruption
+
+                Function task = std::move(wl->tasks.    front()); //noexcept thanks to move
+                /**/                      wl->tasks.pop_front();  //
+                dummy.unlock();
 
-        interruptibleWait(conditionNewWork_, dummy, [this] { return !workItems_.empty(); }); //throw ThreadInterruption
-        warn_static("implement FIFO!?")
+                task();
 
-        Function wi = std::move(workItems_.    back()); //
-        /**/                    workItems_.pop_back();  //noexcept thanks to move
-        return wi;                                      //
+                dummy.lock();
+                if (--(wl->tasksPending) == 0)
+                    wl->conditionTasksDone.notify_all(); //too difficult to notify outside the lock
+            }
+        });
     }
+
+    void swap(ThreadGroup& other)
+    {
+        std::swap(worker_,         other.worker_);
+        std::swap(workLoad_,       other.workLoad_);
+        std::swap(detach_,         other.detach_);
+        std::swap(threadCountMax_, other.threadCountMax_);
+        std::swap(groupName_,      other.groupName_);
+    }
+
+    struct WorkLoad
+    {
+        std::mutex lock;
+        RingBuffer<Function> tasks; //FIFO! :)
+        size_t tasksPending = 0;
+        std::condition_variable conditionNewTask;
+        std::condition_variable conditionTasksDone;
+    };
+
     std::vector<InterruptibleThread> worker_;
-    std::mutex lockWork_;
-    std::vector<Function> workItems_;
-    std::condition_variable conditionNewWork_;
+    std::shared_ptr<WorkLoad> workLoad_ = std::make_shared<WorkLoad>();
+    bool detach_ = false;
+    size_t threadCountMax_;
+    std::string groupName_;
 };
 
 
@@ -201,7 +252,7 @@ private:
 namespace impl
 {
 template <class Function> inline
-auto runAsync(Function&& fun, TrueType /*copy-constructible*/)
+auto runAsync(Function&& fun, std::true_type /*copy-constructible*/)
 {
     using ResultType = decltype(fun());
 
@@ -214,11 +265,11 @@ auto runAsync(Function&& fun, TrueType /*copy-constructible*/)
 
 
 template <class Function> inline
-auto runAsync(Function&& fun, FalseType /*copy-constructible*/)
+auto runAsync(Function&& fun, std::false_type /*copy-constructible*/)
 {
     //support move-only function objects!
     auto sharedFun = std::make_shared<Function>(std::forward<Function>(fun));
-    return runAsync([sharedFun] { return (*sharedFun)(); }, TrueType());
+    return runAsync([sharedFun] { return (*sharedFun)(); }, std::true_type());
 }
 }
 
@@ -226,7 +277,7 @@ auto runAsync(Function&& fun, FalseType /*copy-constructible*/)
 template <class Function> inline
 auto runAsync(Function&& fun)
 {
-    return impl::runAsync(std::forward<Function>(fun), StaticBool<std::is_copy_constructible<Function>::value>());
+    return impl::runAsync(std::forward<Function>(fun), std::is_copy_constructible<Function>());
 }
 
 
@@ -308,14 +359,6 @@ Opt<T> GetFirstResult<T>::get() const { return asyncResult_->getResult(jobsTotal
 
 //------------------------------------------------------------------------------------------
 
-//thread_local with non-POD seems to cause memory leaks on VS 14 => pointer only is fine:
-#if   defined __GNUC__ || defined __clang__
-    #define ZEN_THREAD_LOCAL_SPECIFIER __thread
-#else
-    #error "Game over!"
-#endif
-
-
 class ThreadInterruption {};
 
 
@@ -354,7 +397,7 @@ public:
         ZEN_ON_SCOPE_EXIT(setConditionVar(nullptr));
 
         //"interrupted_" is not protected by cv's mutex => signal may get lost!!! e.g. after condition was checked but before the wait begins
-		//=> add artifical time out to mitigate! CPU: 0.25% vs 0% for longer time out!
+        //=> add artifical time out to mitigate! CPU: 0.25% vs 0% for longer time out!
         while (!cv.wait_for(lock, std::chrono::milliseconds(1), [&] { return this->interrupted_ || pred(); }))
             ;
 
@@ -393,7 +436,8 @@ namespace impl
 inline
 InterruptionStatus*& refThreadLocalInterruptionStatus()
 {
-    static ZEN_THREAD_LOCAL_SPECIFIER InterruptionStatus* threadLocalInterruptionStatus = nullptr;
+    //thread_local with non-POD seems to cause memory leaks on VS 14 => pointer only is fine:
+    thread_local InterruptionStatus* threadLocalInterruptionStatus = nullptr;
     return threadLocalInterruptionStatus;
 }
 }
@@ -457,26 +501,6 @@ InterruptibleThread::InterruptibleThread(Function&& f)
 
 inline
 void InterruptibleThread::interrupt() { intStatus_->interrupt(); }
-
-
-
-
-inline
-void setCurrentThreadName(const char* threadName)
-{
-    ::prctl(PR_SET_NAME, threadName, 0, 0, 0);
-
-}
-
-
-inline
-uint64_t getThreadId()
-{
-    //obviously "gettid()" is not available on Ubuntu/Debian/Suse => use the OpenSSL approach:
-    static_assert(sizeof(uint64_t) >= sizeof(void*), "");
-    return reinterpret_cast<uint64_t>(static_cast<void*>(&errno));
-
-}
 }
 
 #endif //THREAD_H_7896323423432235246427