Added Event and EventLoop

Event is a callback that executes either immediately, like a regular
callback, or is posted in an event queue for defered execution.

EventLoop is a queue of events, built on top of the DynamicMail object.
It runs in its own thread and dispatches events as they arrive in the
mail.

Author: Bogdan Marinescu

TESTS/mbed_drivers/event/main.cpp

@@ -0,0 +1,90 @@
+/* mbed Microcontroller Library
+ * Copyright (c) 2016 ARM Limited
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES Ovoid CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "mbed.h"
+#include "greentea-client/test_env.h"
+#include "unity/unity.h"
+#include "utest/utest.h"
+#include "EventLoop.h"
+#include "Event.h"
+#include <stdio.h>
+
+using namespace utest::v1;
+
+static EventLoop queue(16);
+static osThreadId main_thread_id;
+static osThreadId expected_thread_id;
+static volatile uint32_t call_count;
+
+static void test_func() {
+    if (expected_thread_id == NULL) {
+        // We're testing the event queue, so save the queue thread ID for subsequent
+        // tests (and make sure that we're not running in the main context).
+        TEST_ASSERT_NOT_EQUAL((uint32_t)expected_thread_id, (uint32_t)main_thread_id);
+        expected_thread_id = Thread::gettid();
+    } else {
+        TEST_ASSERT_EQUAL((uint32_t)expected_thread_id, (uint32_t)Thread::gettid());
+    }
+    call_count ++;
+}
+
+static void test_immediate_events() {
+    expected_thread_id = main_thread_id;
+    call_count = 0;
+    // Post 10 "regular" events (they'll execute immediately in
+    // the context of the main thread)
+    for (unsigned i = 0; i < 10; i ++) {
+        event(test_func, NULL).call();
+        TEST_ASSERT_EQUAL_UINT32(call_count, i + 1);
+    }
+}
+
+static void test_queued_events() {
+    // We don't know the event thread ID. it'll be set by the first call to test_func
+    expected_thread_id = NULL;
+    call_count = 0;
+    // Start event thread now
+    queue.start();
+    // Post 10 events that will be queued
+    for (unsigned i = 0; i < 10; i ++) {
+        event(test_func, &queue).call();
+    }
+    // Wait for them to finish
+    while (call_count < 10) {
+        wait_ms(10);
+    }
+    // Wait a bit more and check count again to check that no more events are executed
+    wait_ms(200);
+    TEST_ASSERT_EQUAL_UINT32(call_count, 10);
+}
+
+static Case cases[] = {
+    Case("Test immediate events", test_immediate_events),
+    Case("Test queued events", test_queued_events)
+};
+
+static status_t greentea_test_setup(const size_t number_of_cases) {
+    GREENTEA_SETUP(20, "default_auto");
+    return greentea_test_setup_handler(number_of_cases);
+}
+
+static Specification specification(greentea_test_setup, cases, greentea_test_teardown_handler);
+
+int main() {
+    main_thread_id = Thread::gettid();
+    // Run tests
+    Harness::run(specification);
+}

TESTS/mbed_drivers/event_loop/main.cpp

@@ -0,0 +1,76 @@
+/* mbed Microcontroller Library
+ * Copyright (c) 2016 ARM Limited
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES Ovoid CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "mbed.h"
+#include "greentea-client/test_env.h"
+#include "unity/unity.h"
+#include "utest/utest.h"
+#include "EventLoop.h"
+#include "Callback.h"
+#include <stdio.h>
+
+using namespace utest::v1;
+
+static EventLoop loop(16);
+static osThreadId main_thread_id;
+static osThreadId other_thread_id;
+static volatile uint32_t cb_count;
+
+static void cb1() {
+    if (cb_count == 0) {
+        // Check that we don't run in the main thread context
+        TEST_ASSERT_NOT_EQUAL((uint32_t)Thread::gettid(), (uint32_t)main_thread_id);
+        // And save current running context
+        other_thread_id = Thread::gettid();
+    } else {
+        // Check that we're running in the same context as before
+        TEST_ASSERT_EQUAL((uint32_t)Thread::gettid(), (uint32_t)other_thread_id);
+    }
+    cb_count ++;
+}
+
+static void test_event_loop_callbacks() {
+    // Post 10 callbacks
+    for (unsigned i = 0; i < 10; i ++) {
+        loop.post(callback(cb1));
+    }
+    // Wait for all callbacks to finish
+    while (cb_count < 10) {
+        wait_ms(10);
+    }
+    // Wait a bit more and check count again to check that no more events are executed
+    wait_ms(200);
+    TEST_ASSERT_EQUAL_UINT32(cb_count, 10);
+}
+
+static Case cases[] = {
+    Case("Test event loop callbacks", test_event_loop_callbacks)
+};
+
+static status_t greentea_test_setup(const size_t number_of_cases) {
+    GREENTEA_SETUP(20, "default_auto");
+    return greentea_test_setup_handler(number_of_cases);
+}
+
+static Specification specification(greentea_test_setup, cases, greentea_test_teardown_handler);
+
+int main() {
+    // Start event thread
+    main_thread_id = Thread::gettid();
+    loop.start();
+    // Run tests
+    Harness::run(specification);
+}