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# frozen_string_literal: true
module Gitlab
module Database
module BackgroundMigration
module HealthStatus
module Indicators
class WriteAheadLog
include Gitlab::Utils::StrongMemoize
LIMIT = 42
PENDING_WAL_COUNT_SQL = <<~SQL
WITH
current_wal_file AS (
SELECT pg_walfile_name(pg_current_wal_insert_lsn()) AS pg_walfile_name
),
current_wal AS (
SELECT
('x' || substring(pg_walfile_name, 9, 8))::bit(32)::int AS log,
('x' || substring(pg_walfile_name, 17, 8))::bit(32)::int AS seg,
pg_walfile_name
FROM current_wal_file
),
archive_wal AS (
SELECT
('x' || substring(last_archived_wal, 9, 8))::bit(32)::int AS log,
('x' || substring(last_archived_wal, 17, 8))::bit(32)::int AS seg,
last_archived_wal
FROM pg_stat_archiver
)
SELECT ((current_wal.log - archive_wal.log) * 256) + (current_wal.seg - archive_wal.seg) AS pending_wal_count
FROM current_wal, archive_wal
SQL
def initialize(context)
@connection = context.connection
end
def evaluate
return Signals::NotAvailable.new(self.class, reason: 'indicator disabled') unless enabled?
unless pending_wal_count
return Signals::NotAvailable.new(self.class, reason: 'WAL archive queue can not be calculated')
end
if pending_wal_count > LIMIT
Signals::Stop.new(self.class, reason: "WAL archive queue is too big")
else
Signals::Normal.new(self.class, reason: 'WAL archive queue is within limit')
end
end
private
attr_reader :connection
def enabled?
Feature.enabled?(:batched_migrations_health_status_wal, type: :ops)
end
# Returns number of WAL segments pending archival
def pending_wal_count
strong_memoize(:pending_wal_count) do
Gitlab::Database::LoadBalancing::Session.current.use_primary do
connection.execute(PENDING_WAL_COUNT_SQL).to_a.first&.fetch('pending_wal_count')
end
end
end
end
end
end
end
end
end
|
