Enable free lists for multi-value mapping used in all multi-value attributes.

This should reduce the need for compaction which is CPU intensive for some applications.

3 files changed, 40 insertions, 10 deletions

diff --git a/searchlib/src/tests/attribute/attribute_test.cpp b/searchlib/src/tests/attribute/attribute_test.cpp
index ce1344f5c26..f402f536ae2 100644
--- a/searchlib/src/tests/attribute/attribute_test.cpp
+++ b/searchlib/src/tests/attribute/attribute_test.cpp
@@ -2241,7 +2241,22 @@ void testNamePrefix() {
     EXPECT_EQUAL("sfsint32_pc", vS2->getNamePrefix());
     EXPECT_EQUAL("sfsint32_pc.xyz.abc", vSS1->getName());
     EXPECT_EQUAL("sfsint32_pc", vSS1->getNamePrefix());
+}
+
+class MyMultiValueAttribute : public ArrayStringAttribute {
+public:
+    MyMultiValueAttribute(const vespalib::string& name)
+        : ArrayStringAttribute(name, Config(BasicType::STRING, CollectionType::ARRAY))
+    {
+    }
+    bool has_free_lists_enabled() const { return this->_mvMapping.has_free_lists_enabled(); }
+};
 
+void
+test_multi_value_mapping_has_free_lists_enabled()
+{
+    MyMultiValueAttribute attr("mvtest");
+    EXPECT_TRUE(attr.has_free_lists_enabled());
 }
 
 void
@@ -2292,6 +2307,7 @@ int AttributeTest::Main()
     testReaderDuringLastUpdate();
     TEST_DO(testPendingCompaction());
     TEST_DO(testNamePrefix());
+    test_multi_value_mapping_has_free_lists_enabled();
 
     deleteDataDirs();
     TEST_DONE();
diff --git a/searchlib/src/tests/attribute/compaction/attribute_compaction_test.cpp b/searchlib/src/tests/attribute/compaction/attribute_compaction_test.cpp
index c3453783e38..cd2646bbaaf 100644
--- a/searchlib/src/tests/attribute/compaction/attribute_compaction_test.cpp
+++ b/searchlib/src/tests/attribute/compaction/attribute_compaction_test.cpp
@@ -174,9 +174,9 @@ TEST_F("Test that no compaction of int8 array attribute increases address space
     f.populate(range1, 1000);
     f.hammer(range2, 101);
     AddressSpace afterSpace = f.getMultiValueAddressSpaceUsage("after");
-    // 100 * 1000 dead arrays due to new values for docids
+    // Only 1000 dead arrays (due to new values for docids) as free lists are used.
     // 1 reserved array accounted as dead
-    EXPECT_EQUAL(100001u, afterSpace.dead());
+    EXPECT_EQUAL(1001u, afterSpace.dead());
 }
 
 TEST_F("Test that compaction of int8 array attribute limits address space usage", Fixture(compactAddressSpaceAttributeConfig(true)))
diff --git a/searchlib/src/tests/attribute/multi_value_mapping/multi_value_mapping_test.cpp b/searchlib/src/tests/attribute/multi_value_mapping/multi_value_mapping_test.cpp
index 9bbcd71f59d..2f74e9d31f6 100644
--- a/searchlib/src/tests/attribute/multi_value_mapping/multi_value_mapping_test.cpp
+++ b/searchlib/src/tests/attribute/multi_value_mapping/multi_value_mapping_test.cpp
@@ -80,17 +80,19 @@ public:
           _maxSmallArraySize()
     {
     }
-    void setup(uint32_t maxSmallArraySize) {
-        _mvMapping = std::make_unique<MvMapping>(ArrayStoreConfig(maxSmallArraySize,
-                                                                  ArrayStoreConfig::AllocSpec(0, RefType::offsetSize(), 8 * 1024,
-                                                                                              ALLOC_GROW_FACTOR)));
+    void setup(uint32_t maxSmallArraySize, bool enable_free_lists = true) {
+        ArrayStoreConfig config(maxSmallArraySize,
+                                ArrayStoreConfig::AllocSpec(0, RefType::offsetSize(), 8 * 1024, ALLOC_GROW_FACTOR));
+        config.enable_free_lists(enable_free_lists);
+        _mvMapping = std::make_unique<MvMapping>(config);
         _attr = std::make_unique<AttributeType>(*_mvMapping);
         _maxSmallArraySize = maxSmallArraySize;
     }
-    void setup(uint32_t maxSmallArraySize, size_t minArrays, size_t maxArrays, size_t numArraysForNewBuffer) {
-        _mvMapping = std::make_unique<MvMapping>(ArrayStoreConfig(maxSmallArraySize,
-                                                                  ArrayStoreConfig::AllocSpec(minArrays, maxArrays, numArraysForNewBuffer,
-                                                                                              ALLOC_GROW_FACTOR)));
+    void setup(uint32_t maxSmallArraySize, size_t minArrays, size_t maxArrays, size_t numArraysForNewBuffer, bool enable_free_lists = true) {
+        ArrayStoreConfig config(maxSmallArraySize,
+                                ArrayStoreConfig::AllocSpec(minArrays, maxArrays, numArraysForNewBuffer, ALLOC_GROW_FACTOR));
+        config.enable_free_lists(enable_free_lists);
+        _mvMapping = std::make_unique<MvMapping>(config);
         _attr = std::make_unique<AttributeType>(*_mvMapping);
         _maxSmallArraySize = maxSmallArraySize;
     }
@@ -307,6 +309,18 @@ TEST_F(IntMappingTest, test_that_replace_works)
     EXPECT_EQ(4u, getTotalValueCnt());
 }
 
+TEST_F(IntMappingTest, test_that_free_lists_can_be_enabled)
+{
+    setup(3, true);
+    EXPECT_TRUE(_mvMapping->has_free_lists_enabled());
+}
+
+TEST_F(IntMappingTest, test_that_free_lists_can_be_disabled)
+{
+    setup(3, false);
+    EXPECT_FALSE(_mvMapping->has_free_lists_enabled());
+}
+
 TEST_F(CompactionIntMappingTest, test_that_compaction_works)
 {
     setup(3, 64, 512, 129);