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-rw-r--r--jstests/master_slave/master1.js6
-rw-r--r--src/mongo/db/SConscript1
-rw-r--r--src/mongo/db/logical_clock.cpp51
-rw-r--r--src/mongo/db/logical_clock.h5
-rw-r--r--src/mongo/db/logical_clock_test.cpp28
5 files changed, 66 insertions, 25 deletions
diff --git a/jstests/master_slave/master1.js b/jstests/master_slave/master1.js
index 2f5ba3e11eb..2292a061939 100644
--- a/jstests/master_slave/master1.js
+++ b/jstests/master_slave/master1.js
@@ -50,8 +50,6 @@ rt.stop(true);
m = rt.start(true, null, true);
assert.eq(op.ts.i, lastop().ts.i);
-assert.throws(function() {
- am().save({}); // triggers fassert because ofclock skew
-});
+am().save({});
-assert.neq(0, rt.stop(true)); // fasserted
+assert.eq(0, rt.stop(true));
diff --git a/src/mongo/db/SConscript b/src/mongo/db/SConscript
index 68bd5121e5a..f54f36b421a 100644
--- a/src/mongo/db/SConscript
+++ b/src/mongo/db/SConscript
@@ -1009,6 +1009,7 @@ env.Library(
'service_context',
'signed_logical_time',
'time_proof_service',
+ '$BUILD_DIR/mongo/util/clock_source_mock'
],
)
diff --git a/src/mongo/db/logical_clock.cpp b/src/mongo/db/logical_clock.cpp
index 6f0e4c55574..4cdd3177d26 100644
--- a/src/mongo/db/logical_clock.cpp
+++ b/src/mongo/db/logical_clock.cpp
@@ -140,35 +140,48 @@ Status LogicalClock::signAndAdvanceClusterTime(LogicalTime newTime) {
return _advanceClusterTime_inlock(std::move(newSignedTime));
}
-LogicalTime LogicalClock::reserveTicks(uint64_t ticks) {
+LogicalTime LogicalClock::reserveTicks(uint64_t nTicks) {
- invariant(ticks > 0);
+ invariant(nTicks > 0 && nTicks < (1U << 31));
stdx::lock_guard<stdx::mutex> lock(_mutex);
+ LogicalTime clusterTime = _clusterTime.getTime();
+ LogicalTime nextClusterTime;
+
const unsigned wallClockSecs =
durationCount<Seconds>(_service->getFastClockSource()->now().toDurationSinceEpoch());
- unsigned currentSecs = _clusterTime.getTime().asTimestamp().getSecs();
- LogicalTime clusterTimestamp = _clusterTime.getTime();
+ unsigned clusterTimeSecs = clusterTime.asTimestamp().getSecs();
- if (MONGO_unlikely(currentSecs < wallClockSecs)) {
- clusterTimestamp = LogicalTime(Timestamp(wallClockSecs, 1));
- } else {
- clusterTimestamp.addTicks(1);
+ // Synchronize clusterTime with wall clock time, if clusterTime was behind in seconds.
+ if (clusterTimeSecs < wallClockSecs) {
+ clusterTime = LogicalTime(Timestamp(wallClockSecs, 0));
+ }
+ // If reserving 'nTicks' would force the cluster timestamp's increment field to exceed (2^31-1),
+ // overflow by moving to the next second. We use the signed integer maximum as an overflow point
+ // in order to preserve compatibility with potentially signed or unsigned integral Timestamp
+ // increment types. It is also unlikely to apply more than 2^31 oplog entries in the span of one
+ // second.
+ else if (clusterTime.asTimestamp().getInc() >= ((1U << 31) - nTicks)) {
+
+ log() << "Exceeded maximum allowable increment value within one second. Moving clusterTime "
+ "forward to the next second.";
+
+ // Move time forward to the next second
+ clusterTime = LogicalTime(Timestamp(clusterTime.asTimestamp().getSecs() + 1, 0));
}
- auto currentTime = clusterTimestamp;
- clusterTimestamp.addTicks(ticks - 1);
-
- // Fail if time is not moving forward for 2**31 ticks
- if (MONGO_unlikely(clusterTimestamp.asTimestamp().getSecs() > wallClockSecs) &&
- clusterTimestamp.asTimestamp().getInc() >= 1U << 31) {
- mongo::severe() << "clock skew detected, prev: " << wallClockSecs
- << " now: " << clusterTimestamp.asTimestamp().getSecs();
- fassertFailed(17449);
+
+ // Save the next cluster time.
+ clusterTime.addTicks(1);
+ nextClusterTime = clusterTime;
+
+ // Add the rest of the requested ticks if needed.
+ if (nTicks > 1) {
+ clusterTime.addTicks(nTicks - 1);
}
- _clusterTime = _makeSignedLogicalTime(clusterTimestamp);
- return currentTime;
+ _clusterTime = _makeSignedLogicalTime(clusterTime);
+ return nextClusterTime;
}
void LogicalClock::initClusterTimeFromTrustedSource(LogicalTime newTime) {
diff --git a/src/mongo/db/logical_clock.h b/src/mongo/db/logical_clock.h
index 06562c92719..0a4cb99f5fb 100644
--- a/src/mongo/db/logical_clock.h
+++ b/src/mongo/db/logical_clock.h
@@ -84,8 +84,9 @@ public:
SignedLogicalTime getClusterTime();
/**
- * Returns the next clusterTime value and provides the guarantee that the next reserveTicks
- * call will return the value at least nTicks ticks in the future from the current clusterTime.
+ * Returns the next clusterTime value and provides a guarantee that any future call to
+ * reserveTicks() will return a value at least 'nTicks' ticks in the future from the current
+ * clusterTime.
*/
LogicalTime reserveTicks(uint64_t nTicks);
diff --git a/src/mongo/db/logical_clock_test.cpp b/src/mongo/db/logical_clock_test.cpp
index 98c600a1421..f1b75133760 100644
--- a/src/mongo/db/logical_clock_test.cpp
+++ b/src/mongo/db/logical_clock_test.cpp
@@ -26,6 +26,8 @@
* it in the license file.
*/
+#define MONGO_LOG_DEFAULT_COMPONENT ::mongo::logger::LogComponent::kDefault
+
#include "mongo/db/logical_clock.h"
#include "mongo/bson/timestamp.h"
#include "mongo/db/logical_time.h"
@@ -35,6 +37,8 @@
#include "mongo/platform/basic.h"
#include "mongo/stdx/memory.h"
#include "mongo/unittest/unittest.h"
+#include "mongo/util/clock_source_mock.h"
+#include "mongo/util/log.h"
namespace mongo {
namespace {
@@ -49,6 +53,8 @@ protected:
auto pTps = stdx::make_unique<TimeProofService>();
_timeProofService = pTps.get();
_clock = stdx::make_unique<LogicalClock>(_serviceContext.get(), std::move(pTps));
+ _serviceContext->setFastClockSource(
+ stdx::make_unique<SharedClockSourceAdapter>(_mockClockSource));
}
void tearDown() {
@@ -60,6 +66,14 @@ protected:
return _clock.get();
}
+ void setMockClockSourceTime(Date_t time) {
+ _mockClockSource->reset(time);
+ }
+
+ Date_t getMockClockSourceTime() {
+ return _mockClockSource->now();
+ }
+
SignedLogicalTime makeSignedLogicalTime(LogicalTime logicalTime) {
TimeProofService::Key key = {};
return SignedLogicalTime(logicalTime, _timeProofService->getProof(logicalTime, key), 0);
@@ -73,6 +87,8 @@ protected:
private:
TimeProofService* _timeProofService;
std::unique_ptr<ServiceContextNoop> _serviceContext;
+
+ std::shared_ptr<ClockSourceMock> _mockClockSource = std::make_shared<ClockSourceMock>();
std::unique_ptr<LogicalClock> _clock;
};
@@ -89,10 +105,16 @@ TEST_F(LogicalClockTestBase, roundtrip) {
// Verify the reserve ticks functionality.
TEST_F(LogicalClockTestBase, reserveTicks) {
+ // Set clock to a non-zero time, so we can verify wall clock synchronization.
+ setMockClockSourceTime(Date_t::fromMillisSinceEpoch(10 * 1000));
+
auto t1 = getClock()->reserveTicks(1);
auto t2(getClock()->getClusterTime());
ASSERT_TRUE(t1 == t2.getTime());
+ // Make sure we synchronized with the wall clock.
+ ASSERT_TRUE(t2.getTime().asTimestamp().getSecs() == 10);
+
auto t3 = getClock()->reserveTicks(1);
t1.addTicks(1);
ASSERT_TRUE(t3 == t1);
@@ -104,6 +126,12 @@ TEST_F(LogicalClockTestBase, reserveTicks) {
t3 = getClock()->reserveTicks(1);
t1.addTicks(100);
ASSERT_TRUE(t3 == t1);
+
+ // Ensure overflow to a new second.
+ auto initTimeSecs = getClock()->getClusterTime().getTime().asTimestamp().getSecs();
+ getClock()->reserveTicks((1U << 31) - 1);
+ auto newTimeSecs = getClock()->getClusterTime().getTime().asTimestamp().getSecs();
+ ASSERT_TRUE(newTimeSecs == initTimeSecs + 1);
}
// Verify the advanceClusterTime functionality.
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