added soft_reset to MatchData to prepare for re-use

3 files changed, 40 insertions, 0 deletions

diff --git a/searchlib/src/tests/fef/termfieldmodel/termfieldmodel_test.cpp b/searchlib/src/tests/fef/termfieldmodel/termfieldmodel_test.cpp
index 2a6cc2501d8..01c72497246 100644
--- a/searchlib/src/tests/fef/termfieldmodel/termfieldmodel_test.cpp
+++ b/searchlib/src/tests/fef/termfieldmodel/termfieldmodel_test.cpp
@@ -220,4 +220,26 @@ TEST("require that TermFieldMatchData can be tagged as needed or not") {
     EXPECT_TRUE(!tfmd.isNotNeeded());
 }
 
+TEST("require that MatchData soft_reset retains appropriate state") {    
+    auto md = MatchData::makeTestInstance(10, 10);
+    md->set_termwise_limit(0.5);
+    auto *old_term = md->resolveTermField(7); 
+    old_term->tagAsNotNeeded();
+    old_term->populate_fixed()->setElementWeight(21);
+    old_term->resetOnlyDocId(42);
+    EXPECT_EQUAL(md->get_termwise_limit(), 0.5);
+    EXPECT_TRUE(old_term->isNotNeeded());
+    EXPECT_EQUAL(old_term->getFieldId(), 7u);
+    EXPECT_EQUAL(old_term->getWeight(), 21);
+    EXPECT_EQUAL(old_term->getDocId(), 42u);
+    md->soft_reset();
+    auto *new_term = md->resolveTermField(7);
+    EXPECT_EQUAL(new_term, old_term);
+    EXPECT_EQUAL(md->get_termwise_limit(), 1.0);
+    EXPECT_TRUE(!new_term->isNotNeeded());
+    EXPECT_EQUAL(new_term->getFieldId(), 7u);
+    EXPECT_EQUAL(new_term->getWeight(), 21);
+    EXPECT_EQUAL(new_term->getDocId(), TermFieldMatchData::invalidId());
+}
+
 TEST_MAIN() { TEST_RUN_ALL(); }
diff --git a/searchlib/src/vespa/searchlib/fef/matchdata.cpp b/searchlib/src/vespa/searchlib/fef/matchdata.cpp
index 4ce2a7c9299..0c589749112 100644
--- a/searchlib/src/vespa/searchlib/fef/matchdata.cpp
+++ b/searchlib/src/vespa/searchlib/fef/matchdata.cpp
@@ -11,6 +11,15 @@ MatchData::MatchData(const Params &cparams)
 {
 }
 
+void
+MatchData::soft_reset()
+{
+    for (auto &tfmd: _termFields) {
+        tfmd.resetOnlyDocId(TermFieldMatchData::invalidId()).tagAsNeeded();
+    }
+    _termwise_limit = 1.0;
+}
+
 MatchData::UP
 MatchData::makeTestInstance(uint32_t numTermFields, uint32_t fieldIdLimit)
 {
diff --git a/searchlib/src/vespa/searchlib/fef/matchdata.h b/searchlib/src/vespa/searchlib/fef/matchdata.h
index 472b34a823f..5b06f4d37e0 100644
--- a/searchlib/src/vespa/searchlib/fef/matchdata.h
+++ b/searchlib/src/vespa/searchlib/fef/matchdata.h
@@ -58,6 +58,15 @@ public:
      **/
     explicit MatchData(const Params &cparams);
 
+    /**
+     * Reset this match data in such a way that it can be re-used with
+     * either the same search iterator tree or with a new search
+     * iterator tree where the only difference in interaction with the
+     * match data is which terms are unpacked. Note that this will
+     * reset some properties, but not all. Use with caution.
+     **/
+    void soft_reset();
+
     MatchData(const MatchData &rhs) = delete;
     MatchData & operator=(const MatchData &rhs) = delete;