Merge pull request #6775 from vespa-engine/revert-6771-geirst/fix-calc-of-oldest-flushed-serial-in-flush-engine

Revert "Geirst/fix calc of oldest flushed serial in flush engine"

5 files changed, 118 insertions, 180 deletions

diff --git a/searchcore/src/tests/proton/flushengine/CMakeLists.txt b/searchcore/src/tests/proton/flushengine/CMakeLists.txt
index 6e8df3c9b7f..826c9b2390f 100644
--- a/searchcore/src/tests/proton/flushengine/CMakeLists.txt
+++ b/searchcore/src/tests/proton/flushengine/CMakeLists.txt
@@ -1,7 +1,7 @@
 # Copyright 2017 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
 vespa_add_executable(searchcore_flushengine_test_app TEST
     SOURCES
-    flushengine_test.cpp
+    flushengine.cpp
     DEPENDS
     searchcore_flushengine
     searchcore_pcommon
diff --git a/searchcore/src/tests/proton/flushengine/flushengine_test.cpp b/searchcore/src/tests/proton/flushengine/flushengine.cpp
index f668072b9fd..d1a98f1b7d3 100644
--- a/searchcore/src/tests/proton/flushengine/flushengine_test.cpp
+++ b/searchcore/src/tests/proton/flushengine/flushengine.cpp
@@ -3,15 +3,15 @@
 #include <vespa/searchcore/proton/flushengine/cachedflushtarget.h>
 #include <vespa/searchcore/proton/flushengine/flush_engine_explorer.h>
 #include <vespa/searchcore/proton/flushengine/flushengine.h>
-#include <vespa/searchcore/proton/flushengine/i_tls_stats_factory.h>
 #include <vespa/searchcore/proton/flushengine/threadedflushtarget.h>
 #include <vespa/searchcore/proton/flushengine/tls_stats_map.h>
+#include <vespa/searchcore/proton/flushengine/i_tls_stats_factory.h>
 #include <vespa/searchcore/proton/server/igetserialnum.h>
 #include <vespa/searchcore/proton/test/dummy_flush_handler.h>
 #include <vespa/searchcore/proton/test/dummy_flush_target.h>
+#include <vespa/vespalib/testkit/testapp.h>
 #include <vespa/vespalib/data/slime/slime.h>
 #include <vespa/vespalib/test/insertion_operators.h>
-#include <vespa/vespalib/testkit/testapp.h>
 #include <mutex>
 #include <chrono>
 
@@ -42,6 +42,7 @@ public:
     SimpleExecutor()
         : _done()
     {
+        // empty
     }
 
     Task::UP
@@ -112,7 +113,7 @@ public:
     }
 };
 
-using Targets = std::vector<IFlushTarget::SP>;
+typedef std::vector<IFlushTarget::SP> Targets;
 
 using FlushDoneHistory = std::vector<search::SerialNum>;
 
@@ -140,6 +141,7 @@ public:
           _done(targets.size()),
           _flushDoneHistory()
     {
+        // empty
     }
 
     search::SerialNum
@@ -217,6 +219,7 @@ public:
         : _flushedSerial(flushedSerial), _currentSerial(currentSerial),
           _start(start), _done(done), _proceed(proceed)
     {
+        // empty
     }
 
     void run() override {
@@ -245,24 +248,8 @@ public:
     vespalib::Gate    _taskDone;
     Task::UP          _task;
 
-protected:
-    SimpleTarget(const std::string &name, const Type &type, search::SerialNum flushedSerial = 0, bool proceedImmediately = true) :
-        test::DummyFlushTarget(name, type, Component::OTHER),
-        _flushedSerial(flushedSerial),
-        _proceed(),
-        _initDone(),
-        _taskStart(),
-        _taskDone(),
-        _task(std::make_unique<SimpleTask>(_taskStart, _taskDone, &_proceed,
-                                           _flushedSerial, _currentSerial))
-    {
-        if (proceedImmediately) {
-            _proceed.countDown();
-        }
-    }
-
 public:
-    using SP = std::shared_ptr<SimpleTarget>;
+    typedef std::shared_ptr<SimpleTarget> SP;
 
     SimpleTarget(Task::UP task, const std::string &name) :
         test::DummyFlushTarget(name),
@@ -276,14 +263,24 @@ public:
     {
     }
 
+    SimpleTarget(const std::string &name, search::SerialNum flushedSerial = 0, bool proceedImmediately = true) :
+        test::DummyFlushTarget(name),
+        _flushedSerial(flushedSerial),
+        _proceed(),
+        _initDone(),
+        _taskStart(),
+        _taskDone(),
+        _task(new SimpleTask(_taskStart, _taskDone, &_proceed,
+                             _flushedSerial, _currentSerial))
+    {
+        if (proceedImmediately) {
+            _proceed.countDown();
+        }
+    }
     SimpleTarget(search::SerialNum flushedSerial = 0, bool proceedImmediately = true)
         : SimpleTarget("anon", flushedSerial, proceedImmediately)
     { }
 
-    SimpleTarget(const std::string &name, search::SerialNum flushedSerial = 0, bool proceedImmediately = true)
-            : SimpleTarget(name, Type::OTHER, flushedSerial, proceedImmediately)
-    { }
-
     virtual Time
     getLastFlushTime() const override { return fastos::ClockSystem::now(); }
 
@@ -307,13 +304,6 @@ public:
 
 };
 
-class GCTarget : public SimpleTarget {
-public:
-    GCTarget(const vespalib::string &name, search::SerialNum flushedSerial)
-            : SimpleTarget(name, Type::GC, flushedSerial)
-    {}
-};
-
 class AssertedTarget : public SimpleTarget {
 public:
     mutable bool _mgain;
@@ -376,7 +366,10 @@ public:
 public:
     typedef std::shared_ptr<SimpleStrategy> SP;
 
-    SimpleStrategy() {}
+    SimpleStrategy()
+    {
+        // empty
+    }
 
     uint32_t
     indexOf(const IFlushTarget::SP &target) const
@@ -456,14 +449,6 @@ struct Fixture
     {
     }
 
-    void putFlushHandler(const vespalib::string &docTypeName, IFlushHandler::SP handler) {
-        engine.putFlushHandler(DocTypeName(docTypeName), handler);
-    }
-
-    void addTargetToStrategy(IFlushTarget::SP target) {
-        strategy->_targets.push_back(std::move(target));
-    }
-
     std::shared_ptr<SimpleHandler>
     addSimpleHandler(Targets targets)
     {
@@ -486,17 +471,21 @@ struct Fixture
     }
 };
 
+
 TEST_F("require that strategy controls flush target", Fixture(1, IINTERVAL))
 {
     vespalib::Gate fooG, barG;
     std::vector<vespalib::string> order;
-    auto foo = std::make_shared<SimpleTarget>(std::make_unique<AppendTask>("foo", order, fooG), "foo");
-    auto bar = std::make_shared<SimpleTarget>(std::make_unique<AppendTask>("bar", order, barG), "bar");
-    f.addTargetToStrategy(foo);
-    f.addTargetToStrategy(bar);
-
-    auto handler = std::make_shared<SimpleHandler>(Targets({bar, foo}), "anon");
-    f.putFlushHandler("anon", handler);
+    FlushTask::UP fooT(new AppendTask("foo", order, fooG));
+    FlushTask::UP barT(new AppendTask("bar", order, barG));
+    SimpleTarget::SP foo(new SimpleTarget(std::move(fooT), "foo"));
+    SimpleTarget::SP bar(new SimpleTarget(std::move(barT), "bar"));
+    f.strategy->_targets.push_back(foo);
+    f.strategy->_targets.push_back(bar);
+
+    SimpleHandler::SP handler(new SimpleHandler({bar, foo}));
+    DocTypeName dtnvanon("anon");
+    f.engine.putFlushHandler(dtnvanon, handler);
     f.engine.start();
 
     EXPECT_TRUE(fooG.await(LONG_TIMEOUT));
@@ -513,20 +502,25 @@ TEST_F("require that zero handlers does not core", Fixture(2, 50))
 
 TEST_F("require that zero targets does not core", Fixture(2, 50))
 {
-    f.putFlushHandler("foo", std::make_shared<SimpleHandler>(Targets(), "foo"));
-    f.putFlushHandler("bar", std::make_shared<SimpleHandler>(Targets(), "bar"));
+    DocTypeName dtnvfoo("foo");
+    DocTypeName dtnvbar("bar");
+    f.engine.putFlushHandler(dtnvfoo,
+                             IFlushHandler::SP(new SimpleHandler({}, "foo")));
+    f.engine.putFlushHandler(dtnvbar,
+                             IFlushHandler::SP(new SimpleHandler({}, "bar")));
     f.engine.start();
 }
 
 TEST_F("require that oldest serial is found", Fixture(1, IINTERVAL))
 {
-    auto foo = std::make_shared<SimpleTarget>("foo", 10);
-    auto bar = std::make_shared<SimpleTarget>("bar", 20);
-    f.addTargetToStrategy(foo);
-    f.addTargetToStrategy(bar);
-
-    auto handler = std::make_shared<SimpleHandler>(Targets({foo, bar}), "anon", 25);
-    f.putFlushHandler("anon", handler);
+    SimpleTarget::SP foo(new SimpleTarget("foo", 10));
+    SimpleTarget::SP bar(new SimpleTarget("bar", 20));
+    f.strategy->_targets.push_back(foo);
+    f.strategy->_targets.push_back(bar);
+
+    SimpleHandler::SP handler(new SimpleHandler({foo, bar}, "anon", 25));
+    DocTypeName dtnvanon("anon");
+    f.engine.putFlushHandler(dtnvanon, handler);
     f.engine.start();
 
     EXPECT_TRUE(handler->_done.await(LONG_TIMEOUT));
@@ -535,44 +529,24 @@ TEST_F("require that oldest serial is found", Fixture(1, IINTERVAL))
     EXPECT_EQUAL(FlushDoneHistory({ 10, 20, 25 }), handlerFlushDoneHistory);
 }
 
-TEST_F("require that GC targets are not considered when oldest serial is found", Fixture(1, IINTERVAL))
-{
-    auto foo = std::make_shared<SimpleTarget>("foo", 5);
-    auto bar = std::make_shared<GCTarget>("bar", 10);
-    auto baz = std::make_shared<SimpleTarget>("baz", 20);
-    f.addTargetToStrategy(foo);
-    f.addTargetToStrategy(bar);
-    f.addTargetToStrategy(baz);
-
-    auto handler = std::make_shared<SimpleHandler>(Targets({foo, bar, baz}), "handler", 25);
-    f.putFlushHandler("handler", handler);
-    f.engine.start();
-
-    // The targets are flushed in sequence: 'foo', 'bar', 'baz'
-    EXPECT_TRUE(handler->_done.await(LONG_TIMEOUT));
-    EXPECT_EQUAL(25ul, handler->_oldestSerial);
-
-    // Before anything is flushed the oldest serial is 5.
-    // After 'foo' has been flushed the oldest serial is 20 as GC target 'bar' is not considered.
-    EXPECT_EQUAL(FlushDoneHistory({ 5, 20, 20, 25 }), handler->getFlushDoneHistory());
-}
-
 TEST_F("require that oldest serial is found in group", Fixture(2, IINTERVAL))
 {
-    auto fooT1 = std::make_shared<SimpleTarget>("fooT1", 10);
-    auto fooT2 = std::make_shared<SimpleTarget>("fooT2", 20);
-    auto barT1 = std::make_shared<SimpleTarget>("barT1",  5);
-    auto barT2 = std::make_shared<SimpleTarget>("barT2", 15);
-    f.addTargetToStrategy(fooT1);
-    f.addTargetToStrategy(fooT2);
-    f.addTargetToStrategy(barT1);
-    f.addTargetToStrategy(barT2);
-
-    auto fooH = std::make_shared<SimpleHandler>(Targets({fooT1, fooT2}), "fooH", 25);
-    f.putFlushHandler("foo", fooH);
-
-    auto barH = std::make_shared<SimpleHandler>(Targets({barT1, barT2}), "barH", 20);
-    f.putFlushHandler("bar", barH);
+    SimpleTarget::SP fooT1(new SimpleTarget("fooT1", 10));
+    SimpleTarget::SP fooT2(new SimpleTarget("fooT2", 20));
+    SimpleTarget::SP barT1(new SimpleTarget("barT1",  5));
+    SimpleTarget::SP barT2(new SimpleTarget("barT2", 15));
+    f.strategy->_targets.push_back(fooT1);
+    f.strategy->_targets.push_back(fooT2);
+    f.strategy->_targets.push_back(barT1);
+    f.strategy->_targets.push_back(barT2);
+
+    SimpleHandler::SP fooH(new SimpleHandler({fooT1, fooT2}, "fooH", 25));
+    DocTypeName dtnvfoo("foo");
+    f.engine.putFlushHandler(dtnvfoo, fooH);
+
+    SimpleHandler::SP barH(new SimpleHandler({barT1, barT2}, "barH", 20));
+    DocTypeName dtnvbar("bar");
+    f.engine.putFlushHandler(dtnvbar, barH);
 
     f.engine.start();
 
@@ -600,10 +574,11 @@ TEST_F("require that oldest serial is found in group", Fixture(2, IINTERVAL))
 
 TEST_F("require that target can refuse flush", Fixture(2, IINTERVAL))
 {
-    auto target = std::make_shared<SimpleTarget>();
-    auto handler = std::make_shared<SimpleHandler>(Targets({target}));
+    SimpleTarget::SP target(new SimpleTarget());
+    SimpleHandler::SP handler(new SimpleHandler({target}));
     target->_task = searchcorespi::FlushTask::UP();
-    f.putFlushHandler("anon", handler);
+    DocTypeName dtnvanon("anon");
+    f.engine.putFlushHandler(dtnvanon, handler);
     f.engine.start();
 
     EXPECT_TRUE(target->_initDone.await(LONG_TIMEOUT));
@@ -614,9 +589,10 @@ TEST_F("require that target can refuse flush", Fixture(2, IINTERVAL))
 TEST_F("require that targets are flushed when nothing new to flush",
        Fixture(2, IINTERVAL))
 {
-    auto target = std::make_shared<SimpleTarget>("anon", 5); // oldest unflushed serial num = 5
-    auto handler = std::make_shared<SimpleHandler>(Targets({target}), "anon", 4); // current serial num = 4
-    f.putFlushHandler("anon", handler);
+    SimpleTarget::SP target(new SimpleTarget("anon", 5)); // oldest unflushed serial num = 5
+    SimpleHandler::SP handler(new SimpleHandler({target}, "anon", 4)); // current serial num = 4
+    DocTypeName dtnvanon("anon");
+    f.engine.putFlushHandler(dtnvanon, handler);
     f.engine.start();
 
     EXPECT_TRUE(target->_initDone.await(LONG_TIMEOUT));
@@ -626,13 +602,14 @@ TEST_F("require that targets are flushed when nothing new to flush",
 
 TEST_F("require that flushing targets are skipped", Fixture(2, IINTERVAL))
 {
-    auto foo = std::make_shared<SimpleTarget>("foo");
-    auto bar = std::make_shared<SimpleTarget>("bar");
-    f.addTargetToStrategy(foo);
-    f.addTargetToStrategy(bar);
-
-    auto handler = std::make_shared<SimpleHandler>(Targets({bar, foo}));
-    f.putFlushHandler("anon", handler);
+    SimpleTarget::SP foo(new SimpleTarget("foo"));
+    SimpleTarget::SP bar(new SimpleTarget("bar"));
+    f.strategy->_targets.push_back(foo);
+    f.strategy->_targets.push_back(bar);
+
+    SimpleHandler::SP handler(new SimpleHandler({bar, foo}));
+    DocTypeName dtnvanon("anon");
+    f.engine.putFlushHandler(dtnvanon, handler);
     f.engine.start();
 
     EXPECT_TRUE(foo->_taskDone.await(LONG_TIMEOUT));
@@ -641,11 +618,12 @@ TEST_F("require that flushing targets are skipped", Fixture(2, IINTERVAL))
 
 TEST_F("require that updated targets are not skipped", Fixture(2, IINTERVAL))
 {
-    auto target = std::make_shared<SimpleTarget>("target", 1);
-    f.addTargetToStrategy(target);
+    SimpleTarget::SP target(new SimpleTarget("target", 1));
+    f.strategy->_targets.push_back(target);
 
-    auto handler = std::make_shared<SimpleHandler>(Targets({target}), "handler", 0);
-    f.putFlushHandler("handler", handler);
+    SimpleHandler::SP handler(new SimpleHandler({target}, "handler", 0));
+    DocTypeName dtnvhandler("handler");
+    f.engine.putFlushHandler(dtnvhandler, handler);
     f.engine.start();
 
     EXPECT_TRUE(target->_taskDone.await(LONG_TIMEOUT));
@@ -655,7 +633,8 @@ TEST("require that threaded target works")
 {
     SimpleExecutor executor;
     SimpleGetSerialNum getSerialNum;
-    auto target = std::make_shared<ThreadedFlushTarget>(executor, getSerialNum, std::make_shared<SimpleTarget>());
+    IFlushTarget::SP target(new SimpleTarget());
+    target.reset(new ThreadedFlushTarget(executor, getSerialNum, target));
 
     EXPECT_FALSE(executor._done.await(SHORT_TIMEOUT));
     EXPECT_TRUE(target->initFlush(0).get() != NULL);
@@ -664,7 +643,8 @@ TEST("require that threaded target works")
 
 TEST("require that cached target works")
 {
-    auto target = std::make_shared<CachedFlushTarget>(std::make_shared<AssertedTarget>());
+    IFlushTarget::SP target(new AssertedTarget());
+    target.reset(new CachedFlushTarget(target));
     for (uint32_t i = 0; i < 2; ++i) {
         EXPECT_EQUAL(0l, target->getApproxMemoryGain().getBefore());
         EXPECT_EQUAL(0l, target->getApproxMemoryGain().getAfter());
@@ -674,11 +654,12 @@ TEST("require that cached target works")
 
 TEST_F("require that trigger flush works", Fixture(2, IINTERVAL))
 {
-    auto target = std::make_shared<SimpleTarget>("target", 1);
-    f.addTargetToStrategy(target);
+    SimpleTarget::SP target(new SimpleTarget("target", 1));
+    f.strategy->_targets.push_back(target);
 
-    auto handler = std::make_shared<SimpleHandler>(Targets({target}), "handler", 9);
-    f.putFlushHandler("handler", handler);
+    SimpleHandler::SP handler(new SimpleHandler({target}, "handler", 9));
+    DocTypeName dtnvhandler("handler");
+    f.engine.putFlushHandler(dtnvhandler, handler);
     f.engine.start();
     f.engine.triggerFlush();
     EXPECT_TRUE(target->_initDone.await(LONG_TIMEOUT));
@@ -712,13 +693,13 @@ assertThatHandlersInCurrentSet(FlushEngine & engine, const std::vector<const cha
 
 TEST_F("require that concurrency works", Fixture(2, 1))
 {
-    auto target1 = std::make_shared<SimpleTarget>("target1", 1, false);
-    auto target2 = std::make_shared<SimpleTarget>("target2", 2, false);
-    auto target3 = std::make_shared<SimpleTarget>("target3", 3, false);
-    auto handler = std::make_shared<SimpleHandler>(Targets({target1, target2, target3}), "handler", 9);
-    f.putFlushHandler("handler", handler);
+    SimpleTarget::SP target1(new SimpleTarget("target1", 1, false));
+    SimpleTarget::SP target2(new SimpleTarget("target2", 2, false));
+    SimpleTarget::SP target3(new SimpleTarget("target3", 3, false));
+    SimpleHandler::SP handler(new SimpleHandler({target1, target2, target3}, "handler", 9));
+    DocTypeName dtnvhandler("handler");
+    f.engine.putFlushHandler(dtnvhandler, handler);
     f.engine.start();
-
     EXPECT_TRUE(target1->_initDone.await(LONG_TIMEOUT));
     EXPECT_TRUE(target2->_initDone.await(LONG_TIMEOUT));
     EXPECT_TRUE(!target3->_initDone.await(SHORT_TIMEOUT));
@@ -733,11 +714,11 @@ TEST_F("require that concurrency works", Fixture(2, 1))
 
 TEST_F("require that state explorer can list flush targets", Fixture(1, 1))
 {
-    auto target = std::make_shared<SimpleTarget>("target1", 100, false);
-    f.putFlushHandler("handler",
-                      std::make_shared<SimpleHandler>(
-                              Targets({target, std::make_shared<SimpleTarget>("target2", 50, true)}),
-                              "handler", 9));
+    SimpleTarget::SP target = std::make_shared<SimpleTarget>("target1", 100, false);
+    f.engine.putFlushHandler(DocTypeName("handler"),
+            std::make_shared<SimpleHandler>(
+                    Targets({target, std::make_shared<SimpleTarget>("target2", 50, true)}),
+                             "handler", 9));
     f.engine.start();
     target->_initDone.await(LONG_TIMEOUT);
     target->_taskStart.await(LONG_TIMEOUT);
diff --git a/searchcore/src/vespa/searchcore/proton/common/eventlogger.cpp b/searchcore/src/vespa/searchcore/proton/common/eventlogger.cpp
index 5966589d635..78f73742fed 100644
--- a/searchcore/src/vespa/searchcore/proton/common/eventlogger.cpp
+++ b/searchcore/src/vespa/searchcore/proton/common/eventlogger.cpp
@@ -109,17 +109,13 @@ EventLogger::flushStart(const string &name, int64_t beforeMemory, int64_t afterM
 }
 
 void
-EventLogger::flushComplete(const string &name, int64_t elapsedTimeMs, SerialNum flushed,
+EventLogger::flushComplete(const string &name, int64_t elapsedTimeMs,
                            const string &outputPath, size_t outputPathElems)
 {
     JSONStringer jstr;
     jstr.beginObject();
     jstr.appendKey("name").appendString(name);
     jstr.appendKey("time.elapsed.ms").appendInt64(elapsedTimeMs);
-    jstr.appendKey("serialnum")
-            .beginObject()
-            .appendKey("flushed").appendInt64(flushed)
-            .endObject();
     if (!outputPath.empty()) {
         jstr.appendKey("output");
         LogUtil::logDir(jstr, outputPath, outputPathElems);
@@ -128,20 +124,6 @@ EventLogger::flushComplete(const string &name, int64_t elapsedTimeMs, SerialNum
     EV_STATE("flush.complete", jstr.toString().data());
 }
 
-void
-EventLogger::flushPrune(const string &name, SerialNum oldestFlushed)
-{
-    JSONStringer jstr;
-    jstr.beginObject();
-    jstr.appendKey("name").appendString(name);
-    jstr.appendKey("serialnum")
-            .beginObject()
-            .appendKey("oldestflushed").appendInt64(oldestFlushed)
-            .endObject();
-    jstr.endObject();
-    EV_STATE("flush.prune", jstr.toString().data());
-}
-
 namespace {
 
 void
diff --git a/searchcore/src/vespa/searchcore/proton/common/eventlogger.h b/searchcore/src/vespa/searchcore/proton/common/eventlogger.h
index 574e650732a..6ba8852496e 100644
--- a/searchcore/src/vespa/searchcore/proton/common/eventlogger.h
+++ b/searchcore/src/vespa/searchcore/proton/common/eventlogger.h
@@ -41,10 +41,8 @@ public:
                            SerialNum current);
     static void flushComplete(const string &name,
                               int64_t elapsedTimeMs,
-                              SerialNum flushed,
                               const string &outputPath,
                               size_t outputPathElems);
-    static void flushPrune(const string &name, SerialNum oldestFlushed);
     static void loadAttributeStart(const vespalib::string &subDbName, const vespalib::string &attrName);
     static void loadAttributeComplete(const vespalib::string &subDbName,
                                       const vespalib::string &attrName, int64_t elapsedTimeMs);
diff --git a/searchcore/src/vespa/searchcore/proton/flushengine/flushengine.cpp b/searchcore/src/vespa/searchcore/proton/flushengine/flushengine.cpp
index f7e0b7981bb..0d2c556b4d6 100644
--- a/searchcore/src/vespa/searchcore/proton/flushengine/flushengine.cpp
+++ b/searchcore/src/vespa/searchcore/proton/flushengine/flushengine.cpp
@@ -22,23 +22,15 @@ namespace proton {
 
 namespace {
 
-std::pair<search::SerialNum, vespalib::string>
-findOldestFlushedTarget(const IFlushTarget::List &lst, const IFlushHandler &handler)
+search::SerialNum
+findOldestFlushedSerial(const IFlushTarget::List &lst, const IFlushHandler &handler)
 {
-    search::SerialNum oldestFlushedSerial = handler.getCurrentSerialNumber();
-    vespalib::string oldestFlushedName = "null";
-    for (const IFlushTarget::SP &target : lst) {
-        if (target->getType() != IFlushTarget::Type::GC) {
-            search::SerialNum targetFlushedSerial = target->getFlushedSerialNum();
-            if (targetFlushedSerial <= oldestFlushedSerial) {
-                oldestFlushedSerial = targetFlushedSerial;
-                oldestFlushedName = target->getName();
-            }
-        }
+    search::SerialNum ret(handler.getCurrentSerialNumber());
+    for (const IFlushTarget::SP & target : lst) {
+        ret = std::min(ret, target->getFlushedSerialNum());
     }
-    LOG(debug, "Oldest flushed serial for handler='%s', target='%s': %" PRIu64 ".",
-        handler.getName().c_str(), oldestFlushedName.c_str(), oldestFlushedSerial);
-    return std::make_pair(oldestFlushedSerial, oldestFlushedName);
+    LOG(debug, "Oldest flushed serial for '%s' is %" PRIu64 ".", handler.getName().c_str(), ret);
+    return ret;
 }
 
 void
@@ -182,16 +174,6 @@ FlushEngine::Run(FastOS_ThreadInterface *, void *)
     prune();
 }
 
-namespace {
-
-vespalib::string
-createName(const IFlushHandler &handler, const vespalib::string &targetName)
-{
-    return (handler.getName() + "." + targetName);
-}
-
-}
-
 bool
 FlushEngine::prune()
 {
@@ -205,11 +187,7 @@ FlushEngine::prune()
     }
     for (const auto &handler : toPrune) {
         IFlushTarget::List lst = handler->getFlushTargets();
-        auto oldestFlushed = findOldestFlushedTarget(lst, *handler);
-        if (LOG_WOULD_LOG(event)) {
-            EventLogger::flushPrune(createName(*handler, oldestFlushed.second), oldestFlushed.first);
-        }
-        handler->flushDone(oldestFlushed.first);
+        handler->flushDone(findOldestFlushedSerial(lst, *handler));
     }
     return true;
 }
@@ -355,8 +333,7 @@ FlushEngine::flushDone(const FlushContext &ctx, uint32_t taskId)
     }
     if (LOG_WOULD_LOG(event)) {
         FlushStats stats = ctx.getTarget()->getLastFlushStats();
-        EventLogger::flushComplete(ctx.getName(), duration.ms(), ctx.getTarget()->getFlushedSerialNum(),
-                                   stats.getPath(), stats.getPathElementsToLog());
+        EventLogger::flushComplete(ctx.getName(), duration.ms(), stats.getPath(), stats.getPathElementsToLog());
     }
     LOG(debug, "FlushEngine::flushDone(taskId='%d') took '%f' secs", taskId, duration.sec());
     std::lock_guard<std::mutex> guard(_lock);