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|
# frozen_string_literal: true
module Gitlab
module Redis
class MultiStore
include Gitlab::Utils::StrongMemoize
class ReadFromPrimaryError < StandardError
def message
'Value not found on the redis primary store. Read from the redis secondary store successful.'
end
end
class MethodMissingError < StandardError
def message
'Method missing. Falling back to execute method on the redis secondary store.'
end
end
attr_reader :primary_store, :secondary_store, :instance_name
FAILED_TO_READ_ERROR_MESSAGE = 'Failed to read from the redis primary_store.'
FAILED_TO_WRITE_ERROR_MESSAGE = 'Failed to write to the redis primary_store.'
READ_COMMANDS = %i(
get
mget
smembers
scard
).freeze
WRITE_COMMANDS = %i(
set
setnx
setex
sadd
srem
del
pipelined
flushdb
).freeze
def initialize(primary_store, secondary_store, instance_name = nil)
@primary_store = primary_store
@secondary_store = secondary_store
@instance_name = instance_name
validate_stores!
end
READ_COMMANDS.each do |name|
define_method(name) do |*args, &block|
if multi_store_enabled?
read_command(name, *args, &block)
else
secondary_store.send(name, *args, &block) # rubocop:disable GitlabSecurity/PublicSend
end
end
end
WRITE_COMMANDS.each do |name|
define_method(name) do |*args, &block|
if multi_store_enabled?
write_command(name, *args, &block)
else
secondary_store.send(name, *args, &block) # rubocop:disable GitlabSecurity/PublicSend
end
end
end
def method_missing(...)
return @instance.send(...) if @instance # rubocop:disable GitlabSecurity/PublicSend
log_method_missing(...)
secondary_store.send(...) # rubocop:disable GitlabSecurity/PublicSend
end
def respond_to_missing?(command_name, include_private = false)
true
end
# This is needed because of Redis::Rack::Connection is requiring Redis::Store
# https://github.com/redis-store/redis-rack/blob/a833086ba494083b6a384a1a4e58b36573a9165d/lib/redis/rack/connection.rb#L15
# Done similarly in https://github.com/lsegal/yard/blob/main/lib/yard/templates/template.rb#L122
def is_a?(klass)
return true if klass == secondary_store.class
super(klass)
end
alias_method :kind_of?, :is_a?
def to_s
if multi_store_enabled?
primary_store.to_s
else
secondary_store.to_s
end
end
private
def log_method_missing(command_name, *_args)
log_error(MethodMissingError.new, command_name)
increment_method_missing_count(command_name)
end
def read_command(command_name, *args, &block)
if @instance
send_command(@instance, command_name, *args, &block)
else
read_one_with_fallback(command_name, *args, &block)
end
end
def write_command(command_name, *args, &block)
if @instance
send_command(@instance, command_name, *args, &block)
else
write_both(command_name, *args, &block)
end
end
def read_one_with_fallback(command_name, *args, &block)
begin
value = send_command(primary_store, command_name, *args, &block)
rescue StandardError => e
log_error(e, command_name,
multi_store_error_message: FAILED_TO_READ_ERROR_MESSAGE)
end
value ||= fallback_read(command_name, *args, &block)
value
end
def fallback_read(command_name, *args, &block)
value = send_command(secondary_store, command_name, *args, &block)
if value
log_error(ReadFromPrimaryError.new, command_name)
increment_read_fallback_count(command_name)
end
value
end
def write_both(command_name, *args, &block)
begin
send_command(primary_store, command_name, *args, &block)
rescue StandardError => e
log_error(e, command_name,
multi_store_error_message: FAILED_TO_WRITE_ERROR_MESSAGE)
end
send_command(secondary_store, command_name, *args, &block)
end
def multi_store_enabled?
Feature.enabled?(:use_multi_store, default_enabled: :yaml) && !same_redis_store?
end
def same_redis_store?
strong_memoize(:same_redis_store) do
# <Redis client v4.4.0 for redis:///path_to/redis/redis.socket/5>"
primary_store.inspect == secondary_store.inspect
end
end
# rubocop:disable GitlabSecurity/PublicSend
def send_command(redis_instance, command_name, *args, &block)
if block_given?
# Make sure that block is wrapped and executed only on the redis instance that is executing the block
redis_instance.send(command_name, *args) do |*params|
with_instance(redis_instance, *params, &block)
end
else
redis_instance.send(command_name, *args)
end
end
# rubocop:enable GitlabSecurity/PublicSend
def with_instance(instance, *params)
@instance = instance
yield(*params)
ensure
@instance = nil
end
def increment_read_fallback_count(command_name)
@read_fallback_counter ||= Gitlab::Metrics.counter(:gitlab_redis_multi_store_read_fallback_total, 'Client side Redis MultiStore reading fallback')
@read_fallback_counter.increment(command: command_name, instance_name: instance_name)
end
def increment_method_missing_count(command_name)
@method_missing_counter ||= Gitlab::Metrics.counter(:gitlab_redis_multi_store_method_missing_total, 'Client side Redis MultiStore method missing')
@method_missing_counter.increment(command: command_name, innamece_name: instance_name)
end
def validate_stores!
raise ArgumentError, 'primary_store is required' unless primary_store
raise ArgumentError, 'secondary_store is required' unless secondary_store
raise ArgumentError, 'invalid primary_store' unless primary_store.is_a?(::Redis)
raise ArgumentError, 'invalid secondary_store' unless secondary_store.is_a?(::Redis)
end
def log_error(exception, command_name, extra = {})
Gitlab::ErrorTracking.log_exception(
exception,
command_name: command_name,
extra: extra.merge(instance_name: instance_name))
end
end
end
end
|
