Prevent division by zero and large relative changes on very small numbers.

2 files changed, 43 insertions, 4 deletions

diff --git a/searchcore/src/tests/proton/matching/matching_stats_test.cpp b/searchcore/src/tests/proton/matching/matching_stats_test.cpp
index 8b58a9e271c..26eaa127aa3 100644
--- a/searchcore/src/tests/proton/matching/matching_stats_test.cpp
+++ b/searchcore/src/tests/proton/matching/matching_stats_test.cpp
@@ -240,6 +240,39 @@ TEST("requireThatPartitionsAreAddedCorrectly") {
     EXPECT_EQUAL(1.0, all1.getPartition(1).wait_time_max());
 }
 
+TEST("requireThatSoftDoomIsSetAndAdded") {
+    MatchingStats stats;
+    MatchingStats stats2;
+    EXPECT_EQUAL(0ul, stats.softDoomed());
+    EXPECT_EQUAL(0.5, stats.softDoomFactor());
+    stats.softDoomFactor(0.7);
+    stats.softDoomed(3);
+    EXPECT_EQUAL(3ul, stats.softDoomed());
+    EXPECT_EQUAL(0.7, stats.softDoomFactor());
+    stats2.add(stats);
+    EXPECT_EQUAL(3ul, stats2.softDoomed());
+    EXPECT_EQUAL(0.5, stats2.softDoomFactor());  // Not affected by add
+}
+
+TEST("requireThatSoftDoomFacorIsComputedCorrectly") {
+    MatchingStats stats;
+    EXPECT_EQUAL(0ul, stats.softDoomed());
+    EXPECT_EQUAL(0.5, stats.softDoomFactor());
+    stats.softDoomed(1);
+    stats.updatesoftDoomFactor(1.0, 0.5, 2.0);
+    EXPECT_EQUAL(1ul, stats.softDoomed());
+    EXPECT_EQUAL(0.47, stats.softDoomFactor());
+    stats.updatesoftDoomFactor(1.0, 0.5, 2.0);
+    EXPECT_EQUAL(1ul, stats.softDoomed());
+    EXPECT_EQUAL(0.44, stats.softDoomFactor());
+    stats.updatesoftDoomFactor(0.0009, 0.5, 2.0);   // hard limits less than 1ms should be ignored
+    EXPECT_EQUAL(1ul, stats.softDoomed());
+    EXPECT_EQUAL(0.44, stats.softDoomFactor());
+    stats.updatesoftDoomFactor(1.0, 0.0009, 2.0);   // soft limits less than 1ms should be ignored
+    EXPECT_EQUAL(1ul, stats.softDoomed());
+    EXPECT_EQUAL(0.44, stats.softDoomFactor());
+}
+
 TEST_MAIN() {
     TEST_RUN_ALL();
 }
diff --git a/searchcore/src/vespa/searchcore/proton/matching/matching_stats.cpp b/searchcore/src/vespa/searchcore/proton/matching/matching_stats.cpp
index 0bc1807d714..2b4660adc11 100644
--- a/searchcore/src/vespa/searchcore/proton/matching/matching_stats.cpp
+++ b/searchcore/src/vespa/searchcore/proton/matching/matching_stats.cpp
@@ -13,6 +13,8 @@ MatchingStats::Partition &get_writable_partition(std::vector<MatchingStats::Part
     return state[id];
 }
 
+constexpr double MIN_TIMEOUT = 0.001;
+
 } // namespace proton::matching::<unnamed>
 
 MatchingStats::MatchingStats()
@@ -62,6 +64,7 @@ MatchingStats::add(const MatchingStats &rhs)
     _docsReRanked += rhs._docsReRanked;
     _softDoomed += rhs.softDoomed();
 
+
     _queryCollateralTime.add(rhs._queryCollateralTime);
     _queryLatency.add(rhs._queryLatency);
     _matchTime.add(rhs._matchTime);
@@ -75,10 +78,13 @@ MatchingStats::add(const MatchingStats &rhs)
 
 MatchingStats &
 MatchingStats::updatesoftDoomFactor(double hardLimit, double softLimit, double duration) {
-    if (duration < softLimit) {
-        _softDoomFactor += 0.01*(softLimit - duration)/hardLimit;
-    } else {
-        _softDoomFactor += 0.02*(softLimit - duration)/hardLimit;
+    if ((hardLimit >= MIN_TIMEOUT) && (softLimit >= MIN_TIMEOUT)) {
+        double diff = (softLimit - duration)/hardLimit;
+        if (duration < softLimit) {
+            _softDoomFactor += 0.01*diff;
+        } else {
+            _softDoomFactor += 0.02*diff;
+        }
     }
     return *this;
 }