last changes from bloomberg.

cpp/tbb/tbb_unspawned_child.cpp

@@ -0,0 +1,97 @@
+/*
+VIM: let b:lcppflags="-std=c++11 -O2 -pthread"
+VIM: let b:wcppflags="/O2 /EHsc /DWIN32"
+VIM: let b:cppflags=g:Iboost.g:Itbb
+VIM: let b:ldflags=g:Lboost.g:LtbbD
+VIM: let b:ldlibpath=g:Bboost.g:Btbb
+VIM: let b:argv=""
+*/
+#include <cstdio>
+#include <iostream>
+#include <exception>
+#include <thread>
+#include <chrono>
+
+#include <tbb/task.h>
+
+/*
+ *  Conclusion:
+ *      The first task_sheduler_init is configuring number of threads in
+ *      the thread pool. If the task scheduler initialised implicitly then
+ *      the number of threads is the number of cores. To ensure uncomment
+ *      the commented line below.
+ */
+
+class ChildTask : public tbb::task
+{
+    tbb::task * execute()
+    {
+        std::printf( "ChildTask is running.\n" );
+        return nullptr;
+    }
+};
+
+class ContTask : public tbb::task
+{
+    tbb::task * execute()
+    {
+        std::printf( "ContTask is running.\n" );
+        return nullptr;
+    }
+};
+
+tbb::task * t;
+
+struct RootTask : public tbb::task
+{
+    tbb::task * execute()
+    {
+        std::printf( "RootTask is running.\n" );
+
+        auto& c = *new( allocate_continuation()) ContTask();
+        t = &c;
+
+        tbb::task& ctask1 = *new( c.allocate_child() ) ChildTask();
+        tbb::task& ctask2 = *new( c.allocate_child() ) ChildTask();
+        c.set_ref_count( 3 );
+        spawn( ctask1 );
+        spawn( ctask2 );
+
+
+        std::printf( "RootTask is done.\n" );
+
+        return nullptr;
+    }
+};
+
+
+int main ( void )
+{try{
+
+    auto& rtask = *new( tbb::task::allocate_root()) RootTask();
+
+    tbb::task::enqueue( rtask );
+
+    std::this_thread::sleep_for( std::chrono::seconds(1) );
+    std::printf( "After sleep.\n" );
+
+    tbb::task::spawn( *new (t->allocate_child()) tbb::empty_task() );
+
+    std::this_thread::sleep_for( std::chrono::seconds(1) );
+    std::printf( "After second sleep.\n" );
+
+    return 0;
+}
+catch ( const std::exception& e )
+{
+    std::cerr << std::endl
+            << "std::exception(\"" << e.what() << "\")." << std::endl;
+    return 2;
+}
+catch ( ... )
+{
+    std::cerr  << std::endl
+            << "unknown exception." << std::endl;
+    return 1;
+}}
+