mhnsw: return an error if lazy neighbor read failed

sql/vector_mhnsw.cc

@@ -74,6 +74,7 @@ class MHNSW_Context
   size_t vec_len= 0;
   size_t byte_len= 0;
   FVector *target= 0;
+  uint err= 0;
 
   Hash_set<FVectorNode> node_cache{PSI_INSTRUMENT_MEM, FVectorNode::get_key};
 
@@ -142,8 +143,8 @@ float FVectorNode::distance_to(const FVector &other) const
 int FVectorNode::instantiate_vector()
 {
   DBUG_ASSERT(vec == nullptr);
-  if (int err= ctx->table->file->ha_rnd_pos(ctx->table->record[0], ref))
-    return err;
+  if ((ctx->err= ctx->table->file->ha_rnd_pos(ctx->table->record[0], ref)))
+    return ctx->err;
   String buf, *v= ctx->vec_field->val_str(&buf);
   if (unlikely(ctx->byte_len == 0))
   {
@@ -173,13 +174,13 @@ int FVectorNode::instantiate_neighbors(size_t layer)
       graph->field[0]->store(layer, false);
       graph->field[1]->store_binary(ref, ref_len);
       key_copy(key, graph->record[0], graph->key_info, graph->key_info->key_length);
-      if (int err= graph->file->ha_index_read_map(graph->record[0], key,
-                                               HA_WHOLE_KEY, HA_READ_KEY_EXACT))
-        return err;
+      if ((ctx->err= graph->file->ha_index_read_map(graph->record[0], key,
+                                            HA_WHOLE_KEY, HA_READ_KEY_EXACT)))
+        return ctx->err;
 
       String strbuf, *str= graph->field[2]->val_str(&strbuf);
       if (str->length() % ref_len)
-        return HA_ERR_CRASHED; // should not happen, corrupted HNSW index
+        return ctx->err= HA_ERR_CRASHED; // corrupted HNSW index
 
       for (const char *pos= str->ptr(); pos < str->end(); pos+= ref_len)
         neighbors[layer].push_back(ctx->get_node(pos), &ctx->root);
@@ -249,11 +250,15 @@ static int select_neighbors(MHNSW_Context *ctx, size_t layer,
   */
   List<FVectorNode> candidates= candidates_unsafe;
   List<FVectorNode> &neighbors= target.get_neighbors(layer);
+
+  if (ctx->err)
+    return ctx->err;
+
   neighbors.empty();
 
   if (pq.init(10000, 0, cmp_vec, &target) ||
       pq_discard.init(10000, 0, cmp_vec, &target))
-    return HA_ERR_OUT_OF_MEM;
+    return ctx->err= HA_ERR_OUT_OF_MEM;
 
   for (const FVectorNode &candidate : candidates)
   {
@@ -293,10 +298,12 @@ static int select_neighbors(MHNSW_Context *ctx, size_t layer,
 static int write_neighbors(MHNSW_Context *ctx, size_t layer,
                            const FVectorNode &source_node)
 {
-  int err;
   TABLE *graph= ctx->table->hlindex;
   const List<FVectorNode> &new_neighbors= source_node.get_neighbors(layer);
 
+  if (ctx->err)
+    return ctx->err;
+
   size_t total_size= new_neighbors.elements * source_node.get_ref_len();
 
   // Allocate memory for the struct and the flexible array member
@@ -315,23 +322,23 @@ static int write_neighbors(MHNSW_Context *ctx, size_t layer,
   graph->field[2]->store_binary(neighbor_array_bytes, total_size);
 
   if (source_node.is_new())
-    err= graph->file->ha_write_row(graph->record[0]);
+    ctx->err= graph->file->ha_write_row(graph->record[0]);
   else
   {
     uchar *key= static_cast<uchar*>(alloca(graph->key_info->key_length));
     key_copy(key, graph->record[0], graph->key_info, graph->key_info->key_length);
 
-    err= graph->file->ha_index_read_map(graph->record[1], key,
+    ctx->err= graph->file->ha_index_read_map(graph->record[1], key,
                                             HA_WHOLE_KEY, HA_READ_KEY_EXACT);
-    if (!err)
+    if (!ctx->err)
     {
-      err= graph->file->ha_update_row(graph->record[1], graph->record[0]);
-      if (err == HA_ERR_RECORD_IS_THE_SAME)
-        err= 0;
+      ctx->err= graph->file->ha_update_row(graph->record[1], graph->record[0]);
+      if (ctx->err == HA_ERR_RECORD_IS_THE_SAME)
+        ctx->err= 0;
     }
   }
   my_safe_afree(neighbor_array_bytes, total_size);
-  return err;
+  return ctx->err;
 }
 
 
@@ -341,18 +348,19 @@ static int update_second_degree_neighbors(MHNSW_Context *ctx, size_t layer,
 {
   for (const FVectorNode &neigh: node.get_neighbors(layer))
   {
-    neigh.get_neighbors(layer).push_back(&node, &ctx->root);
-    if (neigh.get_neighbors(layer).elements > max_neighbors)
+    List<FVectorNode> &neighneighbors= neigh.get_neighbors(layer);
+    if (ctx->err)
+      return ctx->err;
+    neighneighbors.push_back(&node, &ctx->root);
+    if (neighneighbors.elements > max_neighbors)
     {
-      if (int err= select_neighbors(ctx, layer, neigh,
-                                    neigh.get_neighbors(layer), max_neighbors))
-        return err;
+      if (select_neighbors(ctx, layer, neigh, neighneighbors, max_neighbors))
+        return ctx->err;
     }
-    if (int err= write_neighbors(ctx, layer, neigh))
-      return err;
+    if (write_neighbors(ctx, layer, neigh))
+      return ctx->err;
   }
-
-  return 0;
+  return ctx->err;
 }
 
 
@@ -360,8 +368,8 @@ static int update_neighbors(MHNSW_Context *ctx, size_t layer,
                             uint max_neighbors, const FVectorNode &node)
 {
   // 1. update node's neighbors
-  if (int err= write_neighbors(ctx, layer, node))
-    return err;
+  if (write_neighbors(ctx, layer, node))
+    return ctx->err;
   // 2. update node's neighbors' neighbors (shrink before update)
   return update_second_degree_neighbors(ctx, layer, max_neighbors, node);
 }
@@ -428,7 +436,7 @@ static int search_layer(MHNSW_Context *ctx,
   while (best.elements())
     result->push_front(best.pop(), &ctx->root);
 
-  return 0;
+  return ctx->err;
 }
 
 
@@ -482,10 +490,11 @@ int mhnsw_insert(TABLE *table, KEY *keyinfo)
 
   SCOPE_EXIT([graph](){ graph->file->ha_index_end(); });
 
-  if (int err= graph->file->ha_index_last(graph->record[0]))
+  if ((ctx.err= graph->file->ha_index_last(graph->record[0])))
   {
-    if (err != HA_ERR_END_OF_FILE)
-      return err;
+    if (ctx.err != HA_ERR_END_OF_FILE)
+      return ctx.err;
+    ctx.err= 0;
 
     // First insert!
     FVectorNode target(&ctx, table->file->ref);
@@ -519,16 +528,16 @@ int mhnsw_insert(TABLE *table, KEY *keyinfo)
 
   if (new_node_layer > max_layer)
   {
-    if (int err= write_neighbors(&ctx, max_layer + 1, target))
-      return err;
+    if (write_neighbors(&ctx, max_layer + 1, target))
+      return ctx.err;
     new_node_layer= max_layer;
   }
   else
   {
     for (longlong cur_layer= max_layer; cur_layer > new_node_layer; cur_layer--)
     {
-      if (int err= search_layer(&ctx, start_nodes, 1, cur_layer, &candidates))
-        return err;
+      if (search_layer(&ctx, start_nodes, 1, cur_layer, &candidates))
+        return ctx.err;
       start_nodes= candidates;
       candidates.empty();
     }
@@ -539,15 +548,14 @@ int mhnsw_insert(TABLE *table, KEY *keyinfo)
     uint max_neighbors= (cur_layer == 0)   // heuristics from the paper
      ? thd->variables.mhnsw_max_edges_per_node * 2
      : thd->variables.mhnsw_max_edges_per_node;
-    if (int err= search_layer(&ctx, start_nodes, ef_construction, cur_layer,
-                              &candidates))
-      return err;
-
-    if (int err= select_neighbors(&ctx, cur_layer, target, candidates,
-                                  max_neighbors))
-      return err;
-    if (int err= update_neighbors(&ctx, cur_layer, max_neighbors, target))
-      return err;
+    if (search_layer(&ctx, start_nodes, ef_construction, cur_layer,
+                     &candidates))
+      return ctx.err;
+
+    if (select_neighbors(&ctx, cur_layer, target, candidates, max_neighbors))
+      return ctx.err;
+    if (update_neighbors(&ctx, cur_layer, max_neighbors, target))
+      return ctx.err;
     start_nodes= candidates;
     candidates.empty();
   }
@@ -576,8 +584,8 @@ int mhnsw_first(TABLE *table, KEY *keyinfo, Item *dist, ulonglong limit)
 
   SCOPE_EXIT([graph](){ graph->file->ha_index_end(); });
 
-  if (int err= graph->file->ha_index_last(graph->record[0]))
-    return err;
+  if ((ctx.err= graph->file->ha_index_last(graph->record[0])))
+    return ctx.err;
 
   longlong max_layer= graph->field[0]->val_int();
 
@@ -610,14 +618,14 @@ int mhnsw_first(TABLE *table, KEY *keyinfo, Item *dist, ulonglong limit)
 
   for (size_t cur_layer= max_layer; cur_layer > 0; cur_layer--)
   {
-    if (int err= search_layer(&ctx, start_nodes, 1, cur_layer, &candidates))
-      return err;
+    if (search_layer(&ctx, start_nodes, 1, cur_layer, &candidates))
+      return ctx.err;
     start_nodes= candidates;
     candidates.empty();
   }
 
-  if (int err= search_layer(&ctx, start_nodes, ef_search, 0, &candidates))
-    return err;
+  if (search_layer(&ctx, start_nodes, ef_search, 0, &candidates))
+    return ctx.err;
 
   size_t context_size= limit * h->ref_length + sizeof(ulonglong);
   char *context= thd->alloc(context_size);