Fix memory leak in Context class (#269)

Fix memory leak in Context class

Signed-off-by: Tomasz Szumski <tomasz.szumski@intel.com>

media-proxy/include/mesh/concurrency.h

@@ -50,11 +50,11 @@ class Context {
     Context(Context& parent);
     Context(Context& parent, std::chrono::milliseconds timeout_ms);
 
-    Context *parent;
-    thread::Channel<bool> *ch;
+    Context *parent = nullptr;
+    thread::Channel<bool> *ch = nullptr;
     std::future<void> async_cb;
     std::chrono::milliseconds timeout_ms;
-    std::unique_ptr<std::stop_callback<std::function<void()>>> cb;
+    std::unique_ptr<std::stop_callback<std::function<void()>>> cb = nullptr;
 
     friend Context& Background();
     friend class WithCancel;

media-proxy/src/mesh/concurrency.cc

@@ -12,9 +12,6 @@ namespace mesh {
 namespace context {
 
 Context::Context() : ss(std::stop_source()),
-                     parent(nullptr),
-                     cb(nullptr),
-                     ch(new thread::Channel<bool>(1)),
                      timeout_ms(std::chrono::milliseconds(0))
 {
 }
@@ -55,9 +52,11 @@ Context& Context::operator=(Context&& other) noexcept {
         ss = std::stop_source();
         parent = other.parent;
 
-        cb = std::make_unique<std::stop_callback<std::function<void()>>>(
-            parent->ss.get_token(), [this] { cancel(); }
-        );
+        if (parent) {
+            cb = std::make_unique<std::stop_callback<std::function<void()>>>(
+                parent->ss.get_token(), [this] { cancel(); }
+            );
+        }
 
         timeout_ms = other.timeout_ms;
 
@@ -71,6 +70,10 @@ Context& Context::operator=(Context&& other) noexcept {
             });
         }
 
+        if (ch) {
+            delete ch;
+        }
+
         ch = other.ch;
         other.ch = nullptr;
     }

media-proxy/tests/mesh_context_tests.cc

@@ -0,0 +1,51 @@
+#include <gtest/gtest.h>
+#include "mesh/concurrency.h"
+
+using namespace mesh;
+
+class test_class {
+  public:
+    context::Context _ctx;
+
+    void init(context::Context &ctx) { _ctx = context::WithCancel(ctx); }
+};
+
+/**
+ * Test designed to detect memory leaks in the Context class.
+ *
+ * Run the test with Valgrind to detect memory leaks.
+ * valgrind --leak-check=full ./media_proxy_unit_tests --gtest_filter=*Context*
+ */
+TEST(MeshContext, constructor) {
+    auto ctx = context::WithCancel(context::Background());
+    test_class t;
+    t.init(ctx);
+    {
+        auto ctx2 = context::WithCancel(ctx);
+        t.init(ctx2);
+        mesh::thread::Sleep(ctx2, std::chrono::milliseconds(10));
+        ctx2.cancel();
+    }
+    {
+        context::Context c1;
+        c1 = context::Context();
+    }
+    {
+        context::Context c1 = context::WithTimeout(ctx, std::chrono::milliseconds(10));
+        context::Context c2 = context::WithTimeout(c1, std::chrono::milliseconds(20));
+        context::Context c3 = context::WithTimeout(c2, std::chrono::milliseconds(30));
+        context::Context c4 = context::WithTimeout(c3, std::chrono::milliseconds(40));
+        context::Context c5 = context::WithTimeout(c4, std::chrono::milliseconds(50));
+        context::Context c6 = context::WithTimeout(c5, std::chrono::milliseconds(60));
+        mesh::thread::Sleep(c6, std::chrono::milliseconds(10));
+    }
+    {
+        context::Context c1 = context::WithTimeout(ctx, std::chrono::milliseconds(60));
+        context::Context c2 = context::WithTimeout(c1, std::chrono::milliseconds(50));
+        context::Context c3 = context::WithTimeout(c2, std::chrono::milliseconds(40));
+        context::Context c4 = context::WithTimeout(c3, std::chrono::milliseconds(30));
+        context::Context c5 = context::WithTimeout(c4, std::chrono::milliseconds(20));
+        context::Context c6 = context::WithTimeout(c5, std::chrono::milliseconds(10));
+        mesh::thread::Sleep(c6, std::chrono::milliseconds(10));
+    }
+}