Create topkeys benchmark

Topkeys was recently enhanced to add JSON support, however we are
seeing larger than expected amounts of time in top key
tracking. Create a simple benchmark to assist in measurement /
optimization.

Change-Id: I14a317e86319df88e4a349147840c3e8d8c8004a
Reviewed-on: http://review.couchbase.org/57039
Reviewed-by: Trond Norbye <trond.norbye@gmail.com>
Tested-by: buildbot <build@couchbase.com>

tests/CMakeLists.txt

@@ -12,3 +12,4 @@ ADD_SUBDIRECTORY(logger_test)
 ADD_SUBDIRECTORY(sizes)
 ADD_SUBDIRECTORY(mcbp)
 ADD_SUBDIRECTORY(testapp)
+ADD_SUBDIRECTORY(topkeys)

tests/topkeys/CMakeLists.txt

@@ -0,0 +1,7 @@
+ADD_EXECUTABLE(memcached_topkeys_bench
+               ${PROJECT_SOURCE_DIR}/daemon/topkeys.cc
+               topkeys_bench.cc)
+TARGET_LINK_LIBRARIES(memcached_topkeys_bench cJSON gtest gtest_main platform)
+ADD_TEST(NAME memcached_topkeys_bench
+         WORKING_DIRECTORY ${CMAKE_RUNTIME_OUTPUT_DIRECTORY}
+         COMMAND memcached_topkeys_bench)

tests/topkeys/topkeys_bench.cc

@@ -0,0 +1,57 @@
+/* -*- Mode: C++; tab-width: 4; c-basic-offset: 4; indent-tabs-mode: nil -*- */
+/*
+ *     Copyright 2015 Couchbase, Inc.
+ *
+ *   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 OR CONDITIONS OF ANY KIND, either express or implied.
+ *   See the License for the specific language governing permissions and
+ *   limitations under the License.
+ */
+#include "daemon/topkeys.h"
+
+#include <gtest/gtest.h>
+#include <memory>
+
+
+class TopKeysTest : public ::testing::Test {
+protected:
+    void SetUp() {
+        topkeys.reset(new TopKeys(10));
+    }
+
+    std::unique_ptr<TopKeys> topkeys;
+};
+
+static void dump_key(const char* key, const uint16_t klen,
+                     const char* val, const uint32_t vlen,
+                     const void* cookie) {
+    size_t* count = static_cast<size_t*>(const_cast<void*>(cookie));
+    (*count)++;
+}
+
+TEST_F(TopKeysTest, Basic) {
+    // build list of keys
+    std::vector<std::string> keys;
+    for (int ii = 0; ii < 160; ii++) {
+        keys.emplace_back("topkey_test_" + std::to_string(ii));
+    }
+
+    // loop inserting keys
+    for (int jj = 0; jj < 20000; jj++) {
+        for (auto& key : keys) {
+            topkeys->updateKey(key.c_str(), key.size(), jj);
+        }
+    }
+
+    // Verify we hit all shards inside TopKeys
+    size_t count = 0;
+    topkeys->stats(&count, 0, dump_key);
+    EXPECT_EQ(80, count);
+}