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Merge pull request #26 from vulcanize/canonical_hash_finder
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update canonical header finder functions
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i-norden authored Nov 13, 2020
2 parents ca07107 + b11fb94 commit 013946f
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10 changes: 6 additions & 4 deletions db/migrations/00018_create_check_if_removed_functions.sql
Original file line number Diff line number Diff line change
Expand Up @@ -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 $$
SELECT exists(SELECT *
SELECT exists(SELECT 1
FROM eth.storage_cids
INNER JOIN eth.state_cids ON (storage_cids.state_id = state_cids.id)
INNER JOIN eth.header_cids ON (state_cids.header_id = header_cids.id)
Expand All @@ -12,23 +12,25 @@ AS $$
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

Expand Down
121 changes: 121 additions & 0 deletions db/migrations/00019_updated_canonical_hash_finder_functions.sql
Original file line number Diff line number Diff line change
@@ -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;
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