SERVER-27745: Implement LogicalClock

1 files changed, 118 insertions, 0 deletions

diff --git a/src/mongo/db/logical_clock_test.cpp b/src/mongo/db/logical_clock_test.cpp
new file mode 100644
index 00000000000..cba0cc1faa6
--- /dev/null
+++ b/src/mongo/db/logical_clock_test.cpp
@@ -0,0 +1,118 @@
+/**
+ *    Copyright (C) 2017 MongoDB, Inc.
+ *
+ *    This program is free software: you can redistribute it and/or  modify
+ *    it under the terms of the GNU Affero General Public License, version 3,
+ *    as published by the Free Software Foundation.
+ *
+ *    This program is distributed in the hope that it will be useful,
+ *    but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *    GNU Affero General Public License for more details.
+ *
+ *    You should have received a copy of the GNU Affero General Public License
+ *    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ *    As a special exception, the copyright holders give permission to link the
+ *    code of portions of this program with the OpenSSL library under certain
+ *    conditions as described in each individual source file and distribute
+ *    linked combinations including the program with the OpenSSL library. You
+ *    must comply with the GNU Affero General Public License in all respects for
+ *    all of the code used other than as permitted herein. If you modify file(s)
+ *    with this exception, you may extend this exception to your version of the
+ *    file(s), but you are not obligated to do so. If you do not wish to do so,
+ *    delete this exception statement from your version. If you delete this
+ *    exception statement from all source files in the program, then also delete
+ *    it in the license file.
+ */
+
+#include "mongo/db/logical_clock.h"
+#include "mongo/bson/timestamp.h"
+#include "mongo/db/logical_time.h"
+#include "mongo/db/service_context_noop.h"
+#include "mongo/db/signed_logical_time.h"
+#include "mongo/db/time_proof_service.h"
+#include "mongo/platform/basic.h"
+#include "mongo/stdx/memory.h"
+#include "mongo/unittest/unittest.h"
+
+namespace mongo {
+namespace {
+
+/**
+ * Setup LogicalClock with invalid initial time.
+ */
+class LogicalClockTestBase : public unittest::Test {
+protected:
+    void setUp() {
+        _serviceContext = stdx::make_unique<ServiceContextNoop>();
+        auto pTps = stdx::make_unique<TimeProofService>();
+        _timeProofService = pTps.get();
+        _clock = stdx::make_unique<LogicalClock>(_serviceContext.get(), std::move(pTps), true);
+    }
+
+    void tearDown() {
+        _clock.reset();
+        _serviceContext.reset();
+    }
+
+    LogicalClock* getClock() {
+        return _clock.get();
+    }
+
+    SignedLogicalTime makeSignedLogicalTime(LogicalTime logicalTime) {
+        return SignedLogicalTime(logicalTime, _timeProofService->getProof(logicalTime));
+    }
+
+private:
+    TimeProofService* _timeProofService;
+    std::unique_ptr<ServiceContextNoop> _serviceContext;
+    std::unique_ptr<LogicalClock> _clock;
+};
+
+// Check that the initial time does not change during logicalClock creation.
+TEST_F(LogicalClockTestBase, roundtrip) {
+    // Create different logicalClock instance to validate that the initial time is preserved.
+    ServiceContextNoop serviceContext;
+    Timestamp tX(1);
+    auto pTps = stdx::make_unique<TimeProofService>();
+    auto time = LogicalTime(tX);
+
+    LogicalClock logicalClock(&serviceContext, std::move(pTps), true);
+    logicalClock.initClusterTimeFromTrustedSource(time);
+    auto storedTime(std::move(logicalClock.getClusterTime()));
+
+    ASSERT_TRUE(storedTime.getTime() == time);
+}
+
+// Verify the reserve ticks functionality.
+TEST_F(LogicalClockTestBase, reserveTicks) {
+    auto t1 = getClock()->reserveTicks(1);
+    auto t2(std::move(getClock()->getClusterTime()));
+    ASSERT_TRUE(t1 == t2.getTime());
+
+    auto t3 = getClock()->reserveTicks(1);
+    t1.addTicks(1);
+    ASSERT_TRUE(t3 == t1);
+
+    t3 = getClock()->reserveTicks(100);
+    t1.addTicks(1);
+    ASSERT_TRUE(t3 == t1);
+
+    t3 = getClock()->reserveTicks(1);
+    t1.addTicks(100);
+    ASSERT_TRUE(t3 == t1);
+}
+
+// Verify the advanceClusterTime functionality.
+TEST_F(LogicalClockTestBase, advanceClusterTime) {
+    auto t1 = getClock()->reserveTicks(1);
+    t1.addTicks(100);
+    SignedLogicalTime l1 = makeSignedLogicalTime(t1);
+    ASSERT_OK(getClock()->advanceClusterTime(l1));
+    auto l2(std::move(getClock()->getClusterTime()));
+    ASSERT_TRUE(l1.getTime() == l2.getTime());
+}
+
+}  // unnamed namespace
+}  // namespace mongo