Add a higher level performance test.

native/src/test/test_api.cpp

@@ -2341,6 +2341,38 @@ test_readwrite_cloud()
   Test_Utils::CloudFileAutoDelete cad("readwrite_cloud.zgy", context);
   do_test_readwrite(cad.name(), context);
 }
+
+static void
+read_hammer(std::shared_ptr<IZgyReader> reader, int repeats)
+{
+  const std::array<std::int64_t,3> start{0, 0, 0};
+  const std::array<std::int64_t,3> size{64, 64, 64};
+  std::shared_ptr<float> data(new float[size[0]*size[1]*size[2]]);
+  for (int ii = 0; ii < repeats; ++ii)
+    reader->read(start, size, data.get(), 0);
+}
+
+/**
+ * Hammer the same brick in the same file again and again and ...
+ * To use this for a real performance test you may need to increase
+ * the number of threads and repeats.
+ */
+static void
+test_hammer()
+{
+  using InternalZGY::Environment;
+  const int repeats = Environment::getNumericEnv("OPENZGY_HAMMER_REPEATS", 8);
+  const int threads = Environment::getNumericEnv("OPENZGY_HAMMER_THREADS", 8);
+  const std::string name= Environment::getStringEnv("OPENZGY_HAMMER_NAME",
+                                                    cloud_synt2_name().c_str());
+  std::shared_ptr<IZgyReader> reader =
+    IZgyReader::open(name, Test_Utils::default_sd_context());
+  std::vector<std::thread> workers;
+  for (int ii = 0; ii < threads; ++ii)
+    workers.push_back(std::thread(read_hammer, reader, repeats));
+  for (int ii = 0; ii < threads; ++ii)
+    workers[ii].join();
+}
 #endif
 
 namespace {
@@ -2753,6 +2785,7 @@ public:
     register_test("api.readwrite",           test_readwrite_local);
 #ifdef HAVE_SD
     register_test("api.readwrite_cloud",     test_readwrite_cloud);
+    register_test("api.hammer",              test_hammer);
 #endif
     register_test("api.edgebricks",          test_edgebricks);
     register_test("api.bat_local_1",         test_bat_local_1);