update canonical header finder functions

db/migrations/00018_create_check_if_removed_functions.sql

@@ -3,7 +3,7 @@
 -- returns if a storage node at the provided path was removed in the range > the provided height and <= the provided block hash
 CREATE OR REPLACE FUNCTION was_storage_removed(path BYTEA, height BIGINT, hash VARCHAR(66)) RETURNS BOOLEAN
 AS $$
-  SELECT exists(SELECT *
+  SELECT exists(SELECT 1
 					FROM eth.storage_cids
             INNER JOIN eth.state_cids ON (storage_cids.state_id = state_cids.id)
             INNER JOIN eth.header_cids ON (state_cids.header_id = header_cids.id)
@@ -12,23 +12,25 @@ AS $$
 					AND block_number <= (SELECT block_number
 										FROM eth.header_cids
 										WHERE block_hash = hash)
-					AND storage_cids.node_type = 3);
+					AND storage_cids.node_type = 3
+					LIMIT 1);
 $$ LANGUAGE SQL;
 -- +goose StatementEnd
 
 -- +goose StatementBegin
 -- returns if a state node at the provided path was removed in the range > the provided height and <= the provided block hash
 CREATE OR REPLACE FUNCTION was_state_removed(path BYTEA, height BIGINT, hash VARCHAR(66)) RETURNS BOOLEAN
 AS $$
-  SELECT exists(SELECT *
+  SELECT exists(SELECT 1
 					FROM eth.state_cids
             INNER JOIN eth.header_cids ON (state_cids.header_id = header_cids.id)
 					WHERE state_path = path
 					AND block_number > height
 					AND block_number <= (SELECT block_number
 										FROM eth.header_cids
 										WHERE block_hash = hash)
-					AND state_cids.node_type = 3);
+					AND state_cids.node_type = 3
+					LIMIT 1);
 $$ LANGUAGE SQL;
 -- +goose StatementEnd
 

db/migrations/00019_updated_canonical_hash_finder_functions.sql

@@ -0,0 +1,121 @@
+-- +goose Up
+-- +goose StatementBegin
+CREATE TYPE child_result AS (
+  has_child BOOLEAN,
+  children eth.header_cids[]
+);
+
+CREATE OR REPLACE FUNCTION has_child(hash VARCHAR(66), height BIGINT) RETURNS child_result AS
+$BODY$
+DECLARE
+  child_height INT;
+  temp_child eth.header_cids;
+  new_child_result child_result;
+BEGIN
+  child_height = height + 1;
+  -- short circuit if there are no children
+  SELECT exists(SELECT 1
+                FROM eth.header_cids
+                WHERE parent_hash = hash
+                AND block_number = child_height
+                LIMIT 1)
+  INTO new_child_result.has_child;
+  -- collect all the children for this header
+  IF new_child_result.has_child THEN
+    FOR temp_child IN
+      SELECT * FROM eth.header_cids WHERE parent_hash = hash AND block_number = child_height
+    LOOP
+      new_child_result.children = array_append(new_child_result.children, temp_child);
+    END LOOP;
+  END IF;
+  RETURN new_child_result;
+END
+$BODY$
+LANGUAGE 'plpgsql';
+-- +goose StatementEnd
+
+-- +goose StatementBegin
+CREATE OR REPLACE FUNCTION canonical_header_from_array(headers eth.header_cids[]) RETURNS eth.header_cids AS
+$BODY$
+DECLARE
+  canonical_header eth.header_cids;
+  canonical_child eth.header_cids;
+  header eth.header_cids;
+  current_child_result child_result;
+  child_headers eth.header_cids[];
+  current_header_with_child eth.header_cids;
+  has_children_count INT DEFAULT 0;
+BEGIN
+  -- for each header in the provided set
+  FOREACH header IN ARRAY headers
+  LOOP
+    -- check if it has any children
+    current_child_result = has_child(header.block_hash, header.block_number);
+    IF current_child_result.has_child THEN
+      -- if it does, take note
+      has_children_count = has_children_count + 1;
+      current_header_with_child = header;
+      -- and add the children to the growing set of child headers
+      child_headers = array_cat(child_headers, current_child_result.children);
+    END IF;
+  END LOOP;
+  -- if none of the headers had children, none is more canonical than the other
+  IF has_children_count = 0 THEN
+    -- return the first one selected
+    SELECT * INTO canonical_header FROM unnest(headers) LIMIT 1;
+  -- if only one header had children, it can be considered the heaviest/canonical header of the set
+  ELSIF has_children_count = 1 THEN
+    -- return the only header with a child
+    canonical_header = current_header_with_child;
+  -- if there are multiple headers with children
+  ELSE
+    -- find the canonical header from the child set
+    canonical_child = canonical_header_from_array(child_headers);
+    -- the header that is parent to this header, is the canonical header at this level
+    SELECT * INTO canonical_header FROM unnest(headers)
+    WHERE block_hash = canonical_child.parent_hash;
+  END IF;
+  RETURN canonical_header;
+END
+$BODY$
+LANGUAGE 'plpgsql';
+-- +goose StatementEnd
+
+-- +goose StatementBegin
+CREATE OR REPLACE FUNCTION canonical_header_id(height BIGINT) RETURNS INTEGER AS
+$BODY$
+DECLARE
+  canonical_header eth.header_cids;
+  headers eth.header_cids[];
+  header_count INT;
+  temp_header eth.header_cids;
+BEGIN
+  -- collect all headers at this height
+  FOR temp_header IN
+    SELECT * FROM eth.header_cids WHERE block_number = height
+  LOOP
+    headers = array_append(headers, temp_header);
+  END LOOP;
+  -- count the number of headers collected
+  header_count = array_length(headers, 1);
+  -- if we have less than 1 header, return NULL
+  IF header_count IS NULL OR header_count < 1 THEN
+    RETURN NULL;
+  -- if we have one header, return its id
+  ELSIF header_count = 1 THEN
+    RETURN headers[1].id;
+  -- if we have multiple headers we need to determine which one is canonical
+  ELSE
+    canonical_header = canonical_header_from_array(headers);
+    RETURN canonical_header.id;
+  END IF;
+END;
+$BODY$
+LANGUAGE 'plpgsql';
+-- +goose StatementEnd
+
+-- +goose Down
+DROP FUNCTION canonical_header_id;
+DROP FUNCTION canonical_header_from_array;
+DROP FUNCTION has_child;
+DROP TYPE child_result;