rgw/sfs: testing: add TestSFSConnectionPool

Signed-off-by: Tim Serong <tserong@suse.com>

src/test/rgw/sfs/CMakeLists.txt

@@ -21,3 +21,4 @@ add_s3gw_test(unittest_rgw_sfs_object_state_machine test_rgw_sfs_object_state_ma
 add_s3gw_test(unittest_rgw_sfs_retry test_rgw_sfs_retry.cc)
 add_s3gw_test(unittest_rgw_sfs_concurrency test_rgw_sfs_concurrency.cc)
 add_s3gw_test(unittest_rgw_sfs_wal_checkpoint test_rgw_sfs_wal_checkpoint.cc)
+add_s3gw_test(unittest_rgw_sfs_connection_pool test_rgw_sfs_connection_pool.cc)

src/test/rgw/sfs/test_rgw_sfs_connection_pool.cc

@@ -0,0 +1,77 @@
+// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
+// vim: ts=8 sw=2 smarttab
+
+#include <gtest/gtest.h>
+
+#include "rgw/driver/sfs/sqlite/dbconn.h"
+#include "rgw/rgw_sal_sfs.h"
+
+using namespace rgw::sal::sfs::sqlite;
+
+namespace fs = std::filesystem;
+
+const static std::string TEST_DIR = "rgw_sfs_tests";
+
+class TestSFSConnectionPool : public ::testing::Test {
+ protected:
+  const std::unique_ptr<CephContext> cct;
+  const fs::path test_dir;
+  std::unique_ptr<rgw::sal::SFStore> store;
+
+  TestSFSConnectionPool()
+      : cct(new CephContext(CEPH_ENTITY_TYPE_ANY)),
+        test_dir(fs::temp_directory_path() / TEST_DIR) {
+    fs::create_directory(test_dir);
+    cct->_conf.set_val("rgw_sfs_data_path", test_dir);
+    cct->_log->start();
+    store.reset(new rgw::sal::SFStore(cct.get(), test_dir));
+  }
+
+  ~TestSFSConnectionPool() override {
+    store.reset();
+    fs::remove_all(test_dir);
+  }
+};
+
+TEST_F(TestSFSConnectionPool, verify_one_connection_per_thread) {
+  DBConnRef conn = store->db_conn;
+
+  // At this point there should be only one connection in the pool.
+  // Alas, DBConn::storage_pool is private, but DBConn::all_sqlite_conns
+  // is a reasonably proxy for this.
+  EXPECT_EQ(conn->all_sqlite_conns.size(), 1);
+
+  std::set<StorageRef> storages;
+  storages.emplace(conn->get_storage());
+
+  // Having now called get_storage from the main thread, we should
+  // still have only one connection.
+  EXPECT_EQ(conn->all_sqlite_conns.size(), 1);
+
+  std::shared_mutex mutex;
+  std::vector<std::thread> threads;
+  const size_t num_threads = 10;
+  for (size_t i = 0; i < num_threads; ++i) {
+    std::thread t([&]() {
+      // Multiple calls to get_storage() in a new thread should return
+      // the same pointer...
+      StorageRef s1 = conn->get_storage();
+      StorageRef s2 = conn->get_storage();
+      EXPECT_EQ(s1, s2);
+
+      // ...and that pointer shouldn't be in use by any other thread.
+      std::unique_lock lock(mutex);
+      EXPECT_EQ(storages.find(s1), storages.end());
+
+      // Now we have to save it so this check works for the other threads.
+      storages.emplace(s1);
+    });
+    threads.push_back(std::move(t));
+  }
+  for (size_t i = 0; i < num_threads; ++i) {
+    threads[i].join();
+  }
+
+  // Now there should be the original connection, plus ten more
+  EXPECT_EQ(conn->all_sqlite_conns.size(), 1 + num_threads);
+}