Compact HnswNodeidMapping.

5 files changed, 80 insertions, 1 deletions

diff --git a/searchlib/src/tests/tensor/hnsw_nodeid_mapping/hnsw_nodeid_mapping_test.cpp b/searchlib/src/tests/tensor/hnsw_nodeid_mapping/hnsw_nodeid_mapping_test.cpp
index 3dba1aa44ac..bc1417e325a 100644
--- a/searchlib/src/tests/tensor/hnsw_nodeid_mapping/hnsw_nodeid_mapping_test.cpp
+++ b/searchlib/src/tests/tensor/hnsw_nodeid_mapping/hnsw_nodeid_mapping_test.cpp
@@ -2,14 +2,17 @@
 
 #include <vespa/searchlib/tensor/hnsw_nodeid_mapping.h>
 #include <vespa/searchlib/tensor/hnsw_node.h>
+#include <vespa/vespalib/datastore/compaction_strategy.h>
 #include <vespa/vespalib/gtest/gtest.h>
 
 using namespace search::tensor;
+using vespalib::datastore::CompactionStrategy;
 using vespalib::datastore::EntryRef;
 
 class HnswNodeidMappingTest : public ::testing::Test {
 public:
     using NodeidVector = std::vector<uint32_t>;
+    using NodeidVectorVector = std::vector<NodeidVector>;
     HnswNodeidMapping mapping;
 
     HnswNodeidMappingTest()
@@ -27,6 +30,27 @@ public:
         auto ids = mapping.get_ids(docid);
         EXPECT_EQ(exp_ids, NodeidVector(ids.begin(), ids.end()));
     }
+    NodeidVector get_id_vector(uint32_t docid) {
+        auto ids = mapping.get_ids(docid);
+        return { ids.begin(), ids.end() };
+    }
+    NodeidVectorVector get_id_vectors(uint32_t docid_limit) {
+        NodeidVectorVector id_vectors;
+        id_vectors.reserve(docid_limit);
+        for (uint32_t docid = 0; docid < docid_limit; ++docid) {
+            id_vectors.push_back(get_id_vector(docid));
+        }
+        return id_vectors;
+    }
+    void expect_id_vectors(const NodeidVectorVector& exp) {
+        for (uint32_t docid = 0; docid < exp.size(); ++docid) {
+            EXPECT_EQ(exp[docid], get_id_vector(docid));
+        }
+    }
+    void drop_held_memory() {
+        mapping.assign_generation(1);
+        mapping.reclaim_memory(2);
+    }
 };
 
 
@@ -107,5 +131,38 @@ TEST_F(HnswNodeidMappingTest, memory_usage_increases_when_allocating_nodeids)
     EXPECT_GT(b.usedBytes(), a.usedBytes());
 }
 
+TEST_F(HnswNodeidMappingTest, compaction_works)
+{
+    const uint32_t docid_limit = 20000;
+    const uint32_t min_multinode_docid = 4;
+    for (uint32_t docid = 1; docid < docid_limit; ++docid) {
+        mapping.allocate_ids(docid, 1);
+    }
+    CompactionStrategy compaction_strategy;
+    (void) mapping.update_stat(compaction_strategy);
+    EXPECT_FALSE(mapping.consider_compact());
+    for (uint32_t docid = min_multinode_docid; docid < docid_limit; ++docid) {
+        mapping.free_ids(docid);
+        drop_held_memory();
+        mapping.allocate_ids(docid, 2);
+    }
+    auto id_vectors = get_id_vectors(docid_limit);
+    auto mem_before = mapping.update_stat(compaction_strategy);
+    EXPECT_EQ(0, mem_before.allocatedBytesOnHold());
+    EXPECT_LT(0, mem_before.usedBytes());
+    EXPECT_TRUE(mapping.consider_compact());
+    mapping.compact_worst(compaction_strategy);
+    EXPECT_FALSE(mapping.consider_compact());
+    auto mem_after = mapping.update_stat(compaction_strategy);
+    drop_held_memory();
+    auto mem_after_drop = mapping.update_stat(compaction_strategy);
+    EXPECT_LT(0, mem_after.allocatedBytesOnHold());
+    EXPECT_LT(mem_before.usedBytes(), mem_after.usedBytes());
+    EXPECT_GT(mem_before.deadBytes(), mem_after.deadBytes());
+    EXPECT_EQ(0, mem_after_drop.allocatedBytesOnHold());
+    EXPECT_GT(mem_before.usedBytes(), mem_after_drop.usedBytes());
+    expect_id_vectors(id_vectors);
+}
+
 GTEST_MAIN_RUN_ALL_TESTS()
 
diff --git a/searchlib/src/vespa/searchlib/tensor/hnsw_identity_mapping.h b/searchlib/src/vespa/searchlib/tensor/hnsw_identity_mapping.h
index a126a3167e3..837727b016c 100644
--- a/searchlib/src/vespa/searchlib/tensor/hnsw_identity_mapping.h
+++ b/searchlib/src/vespa/searchlib/tensor/hnsw_identity_mapping.h
@@ -41,6 +41,8 @@ public:
     void on_load(vespalib::ConstArrayRef<HnswSimpleNode> nodes) { (void) nodes; }
     vespalib::MemoryUsage memory_usage() const { return vespalib::MemoryUsage(); }
     vespalib::MemoryUsage update_stat(const vespalib::datastore::CompactionStrategy&) { return vespalib::MemoryUsage(); }
+    static bool consider_compact() noexcept { return false; }
+    static void compact_worst(const vespalib::datastore::CompactionStrategy&) {}
 };
 
 }
diff --git a/searchlib/src/vespa/searchlib/tensor/hnsw_index.cpp b/searchlib/src/vespa/searchlib/tensor/hnsw_index.cpp
index 4d37cef29c1..5483a0d2de4 100644
--- a/searchlib/src/vespa/searchlib/tensor/hnsw_index.cpp
+++ b/searchlib/src/vespa/searchlib/tensor/hnsw_index.cpp
@@ -669,6 +669,10 @@ HnswIndex<type>::consider_compact(const CompactionStrategy& compaction_strategy)
         compact_link_arrays(compaction_strategy);
         result = true;
     }
+    if (_id_mapping.consider_compact()) {
+        _id_mapping.compact_worst(compaction_strategy);
+        result = true;
+    }
     return result;
 }
 
diff --git a/searchlib/src/vespa/searchlib/tensor/hnsw_nodeid_mapping.cpp b/searchlib/src/vespa/searchlib/tensor/hnsw_nodeid_mapping.cpp
index 215163ba6b1..bcfd0f3beeb 100644
--- a/searchlib/src/vespa/searchlib/tensor/hnsw_nodeid_mapping.cpp
+++ b/searchlib/src/vespa/searchlib/tensor/hnsw_nodeid_mapping.cpp
@@ -43,7 +43,7 @@ HnswNodeidMapping::allocate_id()
 }
 
 HnswNodeidMapping::HnswNodeidMapping()
-    : _refs(),
+    : _refs(1),
       _grow_strategy(16, 1.0, 0, 0), // These are the same parameters as the default in rcuvector.h
       _nodeid_limit(1), // Starting with nodeid=1 matches that we also start with docid=1.
       _nodeids(NodeidStore::optimizedConfigForHugePage(max_small_array_type_id,
@@ -251,4 +251,18 @@ HnswNodeidMapping::update_stat(const CompactionStrategy& compaction_strategy)
     return result;
 }
 
+void
+HnswNodeidMapping::compact_worst(const vespalib::datastore::CompactionStrategy& compaction_strategy)
+{
+    auto compacting_buffers = _nodeids.start_compact_worst_buffers(compaction_strategy);
+    auto filter = compacting_buffers->make_entry_ref_filter();
+   vespalib::ArrayRef<EntryRef> refs(&_refs[0], _refs.size());
+   for (auto& ref : refs) {
+       if (ref.valid() && filter.has(ref)) {
+           ref = _nodeids.move_on_compact(ref);
+       }
+   }
+   compacting_buffers->finish();
+}
+
 }
diff --git a/searchlib/src/vespa/searchlib/tensor/hnsw_nodeid_mapping.h b/searchlib/src/vespa/searchlib/tensor/hnsw_nodeid_mapping.h
index 83bdfc6d122..8adf621b9b3 100644
--- a/searchlib/src/vespa/searchlib/tensor/hnsw_nodeid_mapping.h
+++ b/searchlib/src/vespa/searchlib/tensor/hnsw_nodeid_mapping.h
@@ -58,6 +58,8 @@ public:
     // TODO: Add support for compaction
     vespalib::MemoryUsage memory_usage() const;
     vespalib::MemoryUsage update_stat(const vespalib::datastore::CompactionStrategy& compaction_strategy);
+    bool consider_compact() const noexcept { return _nodeids.consider_compact(); }
+    void compact_worst(const vespalib::datastore::CompactionStrategy& compaction_strategy);
 };
 
 }