Let the InvocationService drive the clock instead of having its own ticking loop.

Also use sleep_until to get intervals indendant of invoke cost as long as cost is within interval.
This also also saves a clock sample and simplifies implementation.

6 files changed, 19 insertions, 62 deletions

diff --git a/staging_vespalib/src/tests/clock/clock_benchmark.cpp b/staging_vespalib/src/tests/clock/clock_benchmark.cpp
index c8d3e2a5aff..a51d83ae4dc 100644
--- a/staging_vespalib/src/tests/clock/clock_benchmark.cpp
+++ b/staging_vespalib/src/tests/clock/clock_benchmark.cpp
@@ -139,17 +139,16 @@ main(int , char *argv[])
     NSVolatile nsVolatile;
     NSAtomic nsAtomic;
     vespalib::InvokeServiceImpl invoker(vespalib::from_s(1.0/frequency));
-    Clock clock;
+    Clock clock(invoker.nowPtr());
     TestClock nsClock(nsValue, 1.0/frequency);
     TestClock nsVolatileClock(nsVolatile, 1.0/frequency);
     TestClock nsAtomicClock(nsAtomic, 1.0/frequency);
-    clock.start(invoker);
     assert(pool.NewThread(&nsClock, nullptr) != nullptr);
     assert(pool.NewThread(&nsVolatileClock, nullptr) != nullptr);
     assert(pool.NewThread(&nsAtomicClock, nullptr) != nullptr);
 
     benchmark("vespalib::Clock", pool, samples, numThreads, [&clock]() {
-        return clock.getTimeNSAssumeRunning();
+        return clock.getTimeNS();
     });
     benchmark("uint64_t", pool, samples, numThreads, [&nsValue]() {
         return steady_time (duration(nsValue._value));
@@ -175,6 +174,5 @@ main(int , char *argv[])
     });
 
     pool.Close();
-    clock.stop();
     return 0;
 }
diff --git a/staging_vespalib/src/tests/clock/clock_test.cpp b/staging_vespalib/src/tests/clock/clock_test.cpp
index 2c6cbc0c876..b8ee4d7cc64 100644
--- a/staging_vespalib/src/tests/clock/clock_test.cpp
+++ b/staging_vespalib/src/tests/clock/clock_test.cpp
@@ -19,19 +19,11 @@ void waitForMovement(steady_time start, Clock & clock, vespalib::duration timeou
 
 TEST("Test that clock is ticking forward") {
     vespalib::InvokeServiceImpl invoker(50ms);
-    Clock clock;
-    clock.start(invoker);
+    Clock clock(invoker.nowPtr());
     steady_time start = clock.getTimeNS();
     waitForMovement(start, clock, 10s);
     steady_time stop = clock.getTimeNS();
     EXPECT_TRUE(stop > start);
-    std::this_thread::sleep_for(1s);
-    start = clock.getTimeNS();
-    waitForMovement(start, clock, 10s);
-    clock.stop();
-    steady_time stop2 = clock.getTimeNS();
-    EXPECT_TRUE(stop2 > stop);
-    EXPECT_TRUE(vespalib::count_ms(stop2 - stop) > 1000);
 }
 
 TEST_MAIN() { TEST_RUN_ALL(); }
\ No newline at end of file
diff --git a/staging_vespalib/src/vespa/vespalib/util/CMakeLists.txt b/staging_vespalib/src/vespa/vespalib/util/CMakeLists.txt
index e69dd36d6f5..2912ac2397b 100644
--- a/staging_vespalib/src/vespa/vespalib/util/CMakeLists.txt
+++ b/staging_vespalib/src/vespa/vespalib/util/CMakeLists.txt
@@ -23,6 +23,7 @@ vespa_add_library(staging_vespalib_vespalib_util OBJECT
     shutdownguard.cpp
     scheduledexecutor.cpp
     singleexecutor.cpp
+    testclock.cpp
     xmlserializable.cpp
     xmlstream.cpp
     DEPENDS
diff --git a/staging_vespalib/src/vespa/vespalib/util/clock.cpp b/staging_vespalib/src/vespa/vespalib/util/clock.cpp
index a4b9ed0fd5d..ad9d6d534f9 100644
--- a/staging_vespalib/src/vespa/vespalib/util/clock.cpp
+++ b/staging_vespalib/src/vespa/vespalib/util/clock.cpp
@@ -1,37 +1,16 @@
 // Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
 
 #include "clock.h"
-#include <vespa/vespalib/util/invokeservice.h>
-
+#include <cassert>
 namespace vespalib {
 
-Clock::Clock() :
-     _timeNS(0u),
-     _running(false),
-     _invokeRegistration()
+Clock::Clock(const std::atomic<steady_time> * source) noexcept
+    : _timeNS(source)
 {
-    setTime();
+    assert(_timeNS != nullptr);
+    static_assert(std::atomic<steady_time>::is_always_lock_free);
 }
 
 Clock::~Clock() = default;
 
-void Clock::setTime() const
-{
-    _timeNS.store(count_ns(steady_clock::now().time_since_epoch()), std::memory_order_relaxed);
-}
-
-void
-Clock::start(InvokeService & invoker)
-{
-    _running.store(true, std::memory_order_relaxed);
-    _invokeRegistration = invoker.registerInvoke([this]() { setTime(); });
-}
-
-void
-Clock::stop()
-{
-    _running.store(false, std::memory_order_relaxed);
-    _invokeRegistration.reset();
-}
-
 }
diff --git a/staging_vespalib/src/vespa/vespalib/util/clock.h b/staging_vespalib/src/vespa/vespalib/util/clock.h
index d4cffc200fe..0d160a98654 100644
--- a/staging_vespalib/src/vespa/vespalib/util/clock.h
+++ b/staging_vespalib/src/vespa/vespalib/util/clock.h
@@ -7,9 +7,6 @@
 
 namespace vespalib {
 
-class IDestructorCallback;
-class InvokeService;
-
 /**
  * Clock is a clock that updates the time at defined intervals.
  * It is intended used where you want to check the time with low cost, but where
@@ -19,28 +16,18 @@ class InvokeService;
 class Clock
 {
 private:
-    mutable std::atomic<int64_t>              _timeNS;
-    std::atomic<bool>                         _running;
-    std::unique_ptr<IDestructorCallback>      _invokeRegistration;
-
-    void setTime() const;
+    const std::atomic<steady_time>                 *_timeNS;
 public:
-    Clock();
+    Clock(const std::atomic<steady_time> * source) noexcept;
+    Clock(const Clock &) = delete;
+    Clock & operator =(const Clock &) = delete;
+    Clock(Clock &&) = delete;
+    Clock & operator =(Clock &&) = delete;
     ~Clock();
 
-    vespalib::steady_time getTimeNS() const {
-        if (!_running) {
-            setTime();
-        }
-        return getTimeNSAssumeRunning();
-    }
-    vespalib::steady_time getTimeNSAssumeRunning() const {
-        return vespalib::steady_time(std::chrono::nanoseconds(_timeNS.load(std::memory_order_relaxed)));
+    vespalib::steady_time getTimeNS() const noexcept {
+        return vespalib::steady_time(_timeNS->load(std::memory_order_relaxed));
     }
-
-    void start(InvokeService & invoker);
-    void stop();
 };
 
 }
-
diff --git a/staging_vespalib/src/vespa/vespalib/util/doom.h b/staging_vespalib/src/vespa/vespalib/util/doom.h
index b9a7e76b8af..e7db0795fb7 100644
--- a/staging_vespalib/src/vespa/vespalib/util/doom.h
+++ b/staging_vespalib/src/vespa/vespalib/util/doom.h
@@ -14,8 +14,8 @@ public:
     Doom(const Clock &clock, steady_time softDoom,
          steady_time hardDoom, bool explicitSoftDoom);
 
-    bool soft_doom() const { return (_clock.getTimeNSAssumeRunning() > _softDoom); }
-    bool hard_doom() const { return (_clock.getTimeNSAssumeRunning() > _hardDoom); }
+    bool soft_doom() const { return (_clock.getTimeNS() > _softDoom); }
+    bool hard_doom() const { return (_clock.getTimeNS() > _hardDoom); }
     duration soft_left() const { return _softDoom - _clock.getTimeNS(); }
     duration hard_left() const { return _hardDoom - _clock.getTimeNS(); }
     bool isExplicitSoftDoom() const { return _isExplicitSoftDoom; }