Compact enum store dictionary when needed.

6 files changed, 129 insertions, 11 deletions

diff --git a/vespalib/src/tests/datastore/unique_store_dictionary/unique_store_dictionary_test.cpp b/vespalib/src/tests/datastore/unique_store_dictionary/unique_store_dictionary_test.cpp
index ce1ebe395ce..7b46196780f 100644
--- a/vespalib/src/tests/datastore/unique_store_dictionary/unique_store_dictionary_test.cpp
+++ b/vespalib/src/tests/datastore/unique_store_dictionary/unique_store_dictionary_test.cpp
@@ -34,25 +34,37 @@ public:
         return resolve(lhs).ref() == resolve(rhs).ref();
     }
     size_t hash(const EntryRef rhs) const override {
-        return rhs.ref();
+        return rhs.valid() ? rhs.ref() : _to_find.ref();
     }
 };
 
 template <typename UniqueStoreDictionaryType>
-struct DictionaryReadTest : public ::testing::Test {
+struct UniqueStoreDictionaryTest : public ::testing::Test {
     UniqueStoreDictionaryType dict;
     std::unique_ptr<IUniqueStoreDictionaryReadSnapshot> snapshot;
+    vespalib::GenerationHandler gen_handler;
 
-    DictionaryReadTest()
+    UniqueStoreDictionaryTest()
         : dict(std::make_unique<Comparator>(0)),
-          snapshot()
+          snapshot(),
+          gen_handler()
     {
     }
-    DictionaryReadTest& add(uint32_t value) {
+    UniqueStoreDictionaryTest& add(uint32_t value) {
         auto result = dict.add(Comparator(value), [=]() noexcept { return EntryRef(value); });
         assert(result.inserted());
         return *this;
     }
+    UniqueStoreDictionaryTest& remove(uint32_t value) {
+        dict.remove(Comparator(value), EntryRef(value));
+        return *this;
+    }
+    void inc_generation() {
+        dict.freeze();
+        dict.transfer_hold_lists(gen_handler.getCurrentGeneration());
+        gen_handler.incGeneration();
+        dict.trim_hold_lists(gen_handler.getFirstUsedGeneration());
+    }
     void take_snapshot() {
         dict.freeze();
         snapshot = dict.get_read_snapshot();
@@ -61,8 +73,8 @@ struct DictionaryReadTest : public ::testing::Test {
     }
 };
 
-using DictionaryReadTestTypes = ::testing::Types<DefaultUniqueStoreDictionary, UniqueStoreDictionary<DefaultDictionary, IUniqueStoreDictionary, ShardedHashMap>, UniqueStoreDictionary<NoBTreeDictionary, IUniqueStoreDictionary, ShardedHashMap>>;
-VESPA_GTEST_TYPED_TEST_SUITE(DictionaryReadTest, DictionaryReadTestTypes);
+using UniqueStoreDictionaryTestTypes = ::testing::Types<DefaultUniqueStoreDictionary, UniqueStoreDictionary<DefaultDictionary, IUniqueStoreDictionary, ShardedHashMap>, UniqueStoreDictionary<NoBTreeDictionary, IUniqueStoreDictionary, ShardedHashMap>>;
+VESPA_GTEST_TYPED_TEST_SUITE(UniqueStoreDictionaryTest, UniqueStoreDictionaryTestTypes);
 
 // Disable warnings emitted by gtest generated files when using typed tests
 #pragma GCC diagnostic push
@@ -70,7 +82,7 @@ VESPA_GTEST_TYPED_TEST_SUITE(DictionaryReadTest, DictionaryReadTestTypes);
 #pragma GCC diagnostic ignored "-Wsuggest-override"
 #endif
 
-TYPED_TEST(DictionaryReadTest, can_count_occurrences_of_a_key)
+TYPED_TEST(UniqueStoreDictionaryTest, can_count_occurrences_of_a_key)
 {
     this->add(3).add(5).take_snapshot();
     EXPECT_EQ(0, this->snapshot->count(Comparator(2)));
@@ -79,7 +91,7 @@ TYPED_TEST(DictionaryReadTest, can_count_occurrences_of_a_key)
     EXPECT_EQ(1, this->snapshot->count(Comparator(5)));
 }
 
-TYPED_TEST(DictionaryReadTest, can_count_occurrences_of_keys_in_a_range)
+TYPED_TEST(UniqueStoreDictionaryTest, can_count_occurrences_of_keys_in_a_range)
 {
     if (!this->dict.get_has_btree_dictionary()) {
         return;
@@ -95,7 +107,7 @@ TYPED_TEST(DictionaryReadTest, can_count_occurrences_of_keys_in_a_range)
     EXPECT_EQ(0, this->snapshot->count_in_range(Comparator(5), Comparator(3)));
 }
 
-TYPED_TEST(DictionaryReadTest, can_iterate_all_keys)
+TYPED_TEST(UniqueStoreDictionaryTest, can_iterate_all_keys)
 {
     using EntryRefVector = std::vector<EntryRef>;
     this->add(3).add(5).add(7).take_snapshot();
@@ -104,7 +116,7 @@ TYPED_TEST(DictionaryReadTest, can_iterate_all_keys)
     EXPECT_EQ(EntryRefVector({EntryRef(3), EntryRef(5), EntryRef(7)}), refs);
 }
 
-TYPED_TEST(DictionaryReadTest, memory_usage_is_reported)
+TYPED_TEST(UniqueStoreDictionaryTest, memory_usage_is_reported)
 {
     auto initial_usage = this->dict.get_memory_usage();
     this->add(10);
@@ -114,6 +126,43 @@ TYPED_TEST(DictionaryReadTest, memory_usage_is_reported)
     EXPECT_EQ(0, usage.allocatedBytesOnHold());
 }
 
+TYPED_TEST(UniqueStoreDictionaryTest, compaction_works)
+{
+    for (uint32_t i = 1; i < 100; ++i) {
+        this->add(i);
+    }
+    for (uint32_t i = 10; i < 100; ++i) {
+        this->remove(i);
+    }
+    this->inc_generation();
+    auto btree_memory_usage_before = this->dict.get_btree_memory_usage();
+    auto hash_memory_usage_before = this->dict.get_hash_memory_usage();
+    for (uint32_t i = 0; i < 15; ++i) {
+        this->dict.compact_worst(true, true);
+    }
+    this->inc_generation();
+    auto btree_memory_usage_after = this->dict.get_btree_memory_usage();
+    auto hash_memory_usage_after = this->dict.get_hash_memory_usage();
+    if (this->dict.get_has_btree_dictionary()) {
+        EXPECT_LT(btree_memory_usage_after.deadBytes(), btree_memory_usage_before.deadBytes());
+    } else {
+        EXPECT_EQ(btree_memory_usage_after.deadBytes(), btree_memory_usage_before.deadBytes());
+    }
+    if (this->dict.get_has_hash_dictionary()) {
+        EXPECT_LT(hash_memory_usage_after.deadBytes(), hash_memory_usage_before.deadBytes());
+    } else {
+        EXPECT_EQ(hash_memory_usage_after.deadBytes(), hash_memory_usage_before.deadBytes());
+    }
+    std::vector<EntryRef> exp_refs;
+    for (uint32_t i = 1; i < 10; ++i) {
+        exp_refs.emplace_back(EntryRef(i));
+    }
+    this->take_snapshot();
+    std::vector<EntryRef> refs;
+    this->snapshot->foreach_key([&](EntryRef ref){ refs.emplace_back(ref); });
+    EXPECT_EQ(exp_refs, refs);
+}
+
 #pragma GCC diagnostic pop
 
 GTEST_MAIN_RUN_ALL_TESTS()
diff --git a/vespalib/src/vespa/vespalib/datastore/i_unique_store_dictionary.h b/vespalib/src/vespa/vespalib/datastore/i_unique_store_dictionary.h
index 4f53a872822..13c389c9a31 100644
--- a/vespalib/src/vespa/vespalib/datastore/i_unique_store_dictionary.h
+++ b/vespalib/src/vespa/vespalib/datastore/i_unique_store_dictionary.h
@@ -39,6 +39,8 @@ public:
     virtual bool get_has_hash_dictionary() const = 0;
     virtual vespalib::MemoryUsage get_btree_memory_usage() const = 0;
     virtual vespalib::MemoryUsage get_hash_memory_usage() const = 0;
+    virtual bool has_held_buffers() const = 0;
+    virtual void compact_worst(bool compact_btree_dictionary, bool compact_hash_dictionary) = 0;
 };
 
 }
diff --git a/vespalib/src/vespa/vespalib/datastore/sharded_hash_map.cpp b/vespalib/src/vespa/vespalib/datastore/sharded_hash_map.cpp
index 36d68873176..a04163f120c 100644
--- a/vespalib/src/vespa/vespalib/datastore/sharded_hash_map.cpp
+++ b/vespalib/src/vespa/vespalib/datastore/sharded_hash_map.cpp
@@ -194,4 +194,30 @@ ShardedHashMap::normalize_values(std::function<EntryRef(EntryRef)> normalize)
     return changed;
 }
 
+bool
+ShardedHashMap::has_held_buffers() const
+{
+    return _gen_holder.getHeldBytes() != 0;
+}
+
+void
+ShardedHashMap::compact_worst()
+{
+    size_t worst_index = 0u;
+    size_t worst_dead_bytes = 0u;
+    for (size_t i = 0; i < num_shards; ++i) {
+        auto map = _maps[i].load(std::memory_order_relaxed);
+        if (map != nullptr) {
+            auto memory_usage = map->get_memory_usage();
+            if (memory_usage.deadBytes() > worst_dead_bytes) {
+                worst_index = i;
+                worst_dead_bytes = memory_usage.deadBytes();
+            }
+        }
+    }
+    if (worst_dead_bytes > 0u) {
+        alloc_shard(worst_index);
+    }
+}
+
 }
diff --git a/vespalib/src/vespa/vespalib/datastore/sharded_hash_map.h b/vespalib/src/vespa/vespalib/datastore/sharded_hash_map.h
index aa787421634..54d6481f34c 100644
--- a/vespalib/src/vespa/vespalib/datastore/sharded_hash_map.h
+++ b/vespalib/src/vespa/vespalib/datastore/sharded_hash_map.h
@@ -58,6 +58,8 @@ public:
     void foreach_key(std::function<void(EntryRef)> callback) const;
     void move_keys(std::function<EntryRef(EntryRef)> callback);
     bool normalize_values(std::function<EntryRef(EntryRef)> normalize);
+    bool has_held_buffers() const;
+    void compact_worst();
 };
 
 }
diff --git a/vespalib/src/vespa/vespalib/datastore/unique_store_dictionary.h b/vespalib/src/vespa/vespalib/datastore/unique_store_dictionary.h
index faaa2294ff3..1775fda7ae3 100644
--- a/vespalib/src/vespa/vespalib/datastore/unique_store_dictionary.h
+++ b/vespalib/src/vespa/vespalib/datastore/unique_store_dictionary.h
@@ -90,6 +90,8 @@ public:
     bool get_has_hash_dictionary() const override;
     vespalib::MemoryUsage get_btree_memory_usage() const override;
     vespalib::MemoryUsage get_hash_memory_usage() const override;
+    bool has_held_buffers() const override;
+    void compact_worst(bool compact_btree_dictionary, bool compact_hash_dictionary) override;
 };
 
 }
diff --git a/vespalib/src/vespa/vespalib/datastore/unique_store_dictionary.hpp b/vespalib/src/vespa/vespalib/datastore/unique_store_dictionary.hpp
index 4a9cf3d96b2..99037b7aaf8 100644
--- a/vespalib/src/vespa/vespalib/datastore/unique_store_dictionary.hpp
+++ b/vespalib/src/vespa/vespalib/datastore/unique_store_dictionary.hpp
@@ -318,4 +318,41 @@ UniqueStoreDictionary<BTreeDictionaryT, ParentT, HashDictionaryT>::get_hash_memo
     return {};
 }
 
+template <typename BTreeDictionaryT, typename ParentT, typename HashDictionaryT>
+bool
+UniqueStoreDictionary<BTreeDictionaryT, ParentT, HashDictionaryT>::has_held_buffers() const
+{
+    if constexpr (has_btree_dictionary) {
+        if (this->_btree_dict.getAllocator().getNodeStore().has_held_buffers()) {
+            return true;
+        }
+    }
+    if constexpr (has_hash_dictionary) {
+        if (this->_hash_dict.has_held_buffers()) {
+            return true;
+        }
+    }
+    return false;
+}
+
+template <typename BTreeDictionaryT, typename ParentT, typename HashDictionaryT>
+void
+UniqueStoreDictionary<BTreeDictionaryT, ParentT, HashDictionaryT>::compact_worst(bool compact_btree_dictionary, bool compact_hash_dictionary)
+{
+    if constexpr (has_btree_dictionary) {
+        if (compact_btree_dictionary) {
+            this->_btree_dict.compact_worst();
+        }
+    } else {
+        (void) compact_btree_dictionary;
+    }
+    if constexpr (has_hash_dictionary) {
+        if (compact_hash_dictionary) {
+            this->_hash_dict.compact_worst();
+        }
+    } else {
+        (void) compact_hash_dictionary;
+    }
+}
+
 }