Add simple test for atomic operations

The test runs some simple tests with the atomic operations in MaxScale.

server/core/test/CMakeLists.txt

@@ -1,3 +1,4 @@
+add_executable(test_atomic testatomic.c)
 add_executable(test_adminusers testadminusers.c)
 add_executable(test_buffer testbuffer.c)
 add_executable(test_dcb testdcb.c)
@@ -22,6 +23,7 @@ add_executable(testmaxscalepcre2 testmaxscalepcre2.c)
 add_executable(testmodulecmd testmodulecmd.c)
 add_executable(testconfig testconfig.c)
 add_executable(trxboundaryparser_profile trxboundaryparser_profile.cc)
+target_link_libraries(test_atomic maxscale-common)
 target_link_libraries(test_adminusers maxscale-common)
 target_link_libraries(test_buffer maxscale-common)
 target_link_libraries(test_dcb maxscale-common)
@@ -46,6 +48,7 @@ target_link_libraries(testmaxscalepcre2 maxscale-common)
 target_link_libraries(testmodulecmd maxscale-common)
 target_link_libraries(testconfig maxscale-common)
 target_link_libraries(trxboundaryparser_profile maxscale-common)
+add_test(TestAtomic test_atomic)
 add_test(TestAdminUsers test_adminusers)
 add_test(TestBuffer test_buffer)
 add_test(TestDCB test_dcb)

server/core/test/testatomic.c

@@ -0,0 +1,88 @@
+/*
+ * Copyright (c) 2016 MariaDB Corporation Ab
+ *
+ * Use of this software is governed by the Business Source License included
+ * in the LICENSE.TXT file and at www.mariadb.com/bsl11.
+ *
+ * Change Date: 2019-07-01
+ *
+ * On the date above, in accordance with the Business Source License, use
+ * of this software will be governed by version 2 or later of the General
+ * Public License.
+ */
+
+#include <maxscale/cdefs.h>
+
+#include <stdio.h>
+
+#include <maxscale/atomic.h>
+#include <maxscale/debug.h>
+#include <maxscale/thread.h>
+
+
+#define NTHR 10
+
+static int running = 0;
+static int expected = 0;
+
+void test_add(void* data)
+{
+    int id = (size_t)data;
+
+    while (atomic_read(&running))
+    {
+        atomic_add(&expected, id);
+        atomic_add(&expected, -id);
+        ss_dassert(atomic_read(&expected) >= 0);
+    }
+}
+
+
+void test_load_store(void* data)
+{
+    int id = (size_t)data;
+
+    while (atomic_read(&running))
+    {
+        if (atomic_read(&expected) % NTHR == id)
+        {
+            ss_dassert(atomic_add(&expected, 1) % NTHR == id + 1);
+        }
+    }
+}
+
+int run_test(void(*func)(void*))
+{
+    THREAD threads[NTHR];
+
+    atomic_write(&expected, 0);
+    atomic_write(&running, 1);
+
+    for (int i = 0; i < NTHR; i++)
+    {
+        if (thread_start(&threads[i], func, NULL) == NULL)
+        {
+            ss_dassert(false);
+        }
+    }
+
+    thread_millisleep(2500);
+    atomic_write(&running, 0);
+
+    for (int i = 0; i < NTHR; i++)
+    {
+        thread_wait(threads[i]);
+    }
+
+    return atomic_read(&expected);
+}
+
+int main(int argc, char** argv)
+{
+    int rval = 0;
+
+    run_test(test_load_store);
+    run_test(test_add);
+
+    return rval;
+}