Merge remote-tracking branch 'origin/master' into concurrent

# Conflicts:
#	lib/main/thread/pithreadpoolexecutor.cpp
#	lib/main/thread/pithreadpoolexecutor.h
#	tests/concurrent/ExecutorIntegrationTest.cpp
#	tests/concurrent/ExecutorUnitTest.cpp
#	tests/concurrent/testutil.h

tests/concurrent/ExecutorIntegrationTest.cpp

@@ -0,0 +1,55 @@
+#include "gtest/gtest.h"
+#include "pithreadpoolexecutor.h"
+#include "pimutex.h"
+#include "testutil.h"
+
+TEST(ExcutorIntegrationTest, execute_is_runnable_invoke) {
+    PIMutex m;
+    int invokedRunnables = 0;
+    PIThreadPoolExecutor executorService(1);
+    executorService.execute([&]() {
+        m.lock();
+        invokedRunnables++;
+        m.unlock();
+    });
+    piMSleep(WAIT_THREAD_TIME_MS);
+	m.lock();
+    ASSERT_EQ(invokedRunnables, 1);
+    m.unlock();
+}
+
+TEST(ExcutorIntegrationTest, execute_is_not_execute_after_shutdown) {
+    volatile bool isRunnableInvoke = false;
+    PIThreadPoolExecutor executorService(1);
+    executorService.shutdown();
+    executorService.execute([&]() {
+        isRunnableInvoke = true;
+    });
+    piMSleep(WAIT_THREAD_TIME_MS);
+    ASSERT_FALSE(isRunnableInvoke);
+}
+
+TEST(ExcutorIntegrationTest, execute_is_execute_before_shutdown) {
+	volatile bool isRunnableInvoke = false;
+    PIThreadPoolExecutor executorService(1);
+    executorService.execute([&]() {
+        piMSleep(WAIT_THREAD_TIME_MS);
+        isRunnableInvoke = true;
+    });
+    executorService.shutdown();
+    piMSleep(2 * WAIT_THREAD_TIME_MS);
+    ASSERT_TRUE(isRunnableInvoke);
+}
+
+TEST(ExcutorIntegrationTest, execute_is_awaitTermination_wait) {
+    PIThreadPoolExecutor executorService(1);
+    executorService.execute([&]() {
+        piMSleep(2 * WAIT_THREAD_TIME_MS);
+    });
+    executorService.shutdown();
+    PITimeMeasurer measurer;
+    ASSERT_TRUE(executorService.awaitTermination(3 * WAIT_THREAD_TIME_MS));
+    double waitTime = measurer.elapsed_m();
+    ASSERT_GE(waitTime, WAIT_THREAD_TIME_MS);
+    ASSERT_LE(waitTime, 4 * WAIT_THREAD_TIME_MS);
+}