[test] Added tests for CUnitQueue

Covers some issues related to Local storage depleted issue Haivision#486

test/filelist.maf

@@ -13,4 +13,5 @@ test_seqno.cpp
 test_socket_options.cpp
 test_sync.cpp
 test_timer.cpp
+test_unitqueue.cpp
 test_utilities.cpp

test/test_unitqueue.cpp

@@ -0,0 +1,88 @@
+#include <array>
+#include <vector>
+#include "gtest/gtest.h"
+#include "queue.h"
+
+
+using namespace std;
+
+
+/// Create CUnitQueue with queue size of 4 units.
+/// The size of 4 is chosen on purpose, because 
+/// CUnitQueue::getNextAvailUnit(..) has the following
+/// condition `if (m_iCount * 10 > m_iSize * 9)`. With m_iSize = 4
+/// it will be false up until m_iCount becomes 4.
+/// And there was an issue in getNextAvailUnit(..) in taking
+/// the very last element of the queue (it was skipped).
+TEST(CUnitQueue, Increase)
+{
+    const int buffer_size_pkts = 4;
+    CUnitQueue unit_queue;
+    unit_queue.init(buffer_size_pkts, 1500, AF_INET);
+
+    vector<CUnit*> taken_units;
+    for (int i = 0; i < 5 * buffer_size_pkts; ++i)
+    {
+        CUnit* unit = unit_queue.getNextAvailUnit();
+        ASSERT_NE(unit, nullptr);
+        unit_queue.makeUnitGood(unit);
+        taken_units.push_back(unit);
+    }
+}
+
+/// Create CUnitQueue with queue size of 4 units.
+/// Then after requesting the 5th unit, free the previous
+/// four units. This makes the previous queue completely free.
+/// Requesting the 5th unit, there would be 3 units available in the
+/// beginning of the same queue.
+TEST(CUnitQueue, IncreaseAndFree)
+{
+    const int buffer_size_pkts = 4;
+    CUnitQueue unit_queue;
+    unit_queue.init(buffer_size_pkts, 1500, AF_INET);
+
+    CUnit* taken_unit = nullptr;
+    for (int i = 0; i < 5 * buffer_size_pkts; ++i)
+    {
+        CUnit* unit = unit_queue.getNextAvailUnit();
+        ASSERT_NE(unit, nullptr);
+        unit_queue.makeUnitGood(unit);
+
+        if (taken_unit)
+            unit_queue.makeUnitFree(taken_unit);
+
+        taken_unit = unit;
+    }
+}
+
+/// Create CUnitQueue with queue size of 4 units.
+/// Then after requesting the 5th unit, free the previous
+/// four units. This makes the previous queue completely free.
+/// Requesting the 9th unit, there would be 4 units available in the
+/// Thus the test checks if 
+TEST(CUnitQueue, IncreaseAndFreeGrouped)
+{
+    const int buffer_size_pkts = 4;
+    CUnitQueue unit_queue;
+    unit_queue.init(buffer_size_pkts, 1500, AF_INET);
+
+    vector<CUnit*> taken_units;
+    for (int i = 0; i < 5 * buffer_size_pkts; ++i)
+    {
+        CUnit* unit = unit_queue.getNextAvailUnit();
+        ASSERT_NE(unit, nullptr);
+        unit_queue.makeUnitGood(unit);
+
+        if (taken_units.size() >= buffer_size_pkts)
+        {
+            for_each(taken_units.begin(), taken_units.end(),
+                [&unit_queue](CUnit* u) { unit_queue.makeUnitFree(u); });
+
+            taken_units.clear();
+        }
+
+        taken_units.push_back(unit);
+        EXPECT_LE(unit_queue.capacity(), 2 * buffer_size_pkts)
+            << "Buffer capacity should not exceed two queues of 4 units";
+    }
+}