/
query_cache.rb
285 lines (237 loc) · 7.86 KB
/
query_cache.rb
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# frozen_string_literal: true
require "concurrent/map"
module ActiveRecord
module ConnectionAdapters # :nodoc:
module QueryCache
DEFAULT_SIZE = 100 # :nodoc:
class << self
def included(base) # :nodoc:
dirties_query_cache base, :exec_query, :execute, :create, :insert, :update, :delete, :truncate,
:truncate_tables, :rollback_to_savepoint, :rollback_db_transaction, :restart_db_transaction,
:exec_insert_all
base.set_callback :checkin, :after, :unset_query_cache!
end
def dirties_query_cache(base, *method_names)
method_names.each do |method_name|
base.class_eval <<-end_code, __FILE__, __LINE__ + 1
def #{method_name}(...)
if pool.dirties_query_cache
ActiveRecord::Base.clear_query_caches_for_current_thread
end
super
end
end_code
end
end
end
class Store # :nodoc:
attr_accessor :enabled, :dirties
alias_method :enabled?, :enabled
alias_method :dirties?, :dirties
def initialize(max_size)
@map = {}
@max_size = max_size
@enabled = false
@dirties = true
end
def size
@map.size
end
def empty?
@map.empty?
end
def [](key)
return unless @enabled
if entry = @map.delete(key)
@map[key] = entry
end
end
def compute_if_absent(key)
return yield unless @enabled
if entry = @map.delete(key)
return @map[key] = entry
end
if @max_size && @map.size >= @max_size
@map.shift # evict the oldest entry
end
@map[key] ||= yield
end
def clear
@map.clear
self
end
end
module ConnectionPoolConfiguration # :nodoc:
def initialize(...)
super
@thread_query_caches = Concurrent::Map.new(initial_capacity: @size)
@query_cache_max_size = \
case query_cache = db_config&.query_cache
when 0, false
nil
when Integer
query_cache
when nil
DEFAULT_SIZE
end
end
def lease_connection(**)
connection = super
connection.query_cache ||= query_cache
connection
end
# Disable the query cache within the block.
def disable_query_cache(dirties: true)
cache = query_cache
old_enabled, cache.enabled, old_dirties, cache.dirties = cache.enabled, false, cache.dirties, dirties
begin
yield
ensure
cache.enabled, cache.dirties = old_enabled, old_dirties
end
end
def enable_query_cache
cache = query_cache
old_enabled, cache.enabled, old_dirties, cache.dirties = cache.enabled, true, cache.dirties, true
begin
yield
ensure
cache.enabled, cache.dirties = old_enabled, old_dirties
end
end
def enable_query_cache!
query_cache.enabled, query_cache.dirties = true, true
end
def disable_query_cache!
query_cache.enabled, query_cache.dirties = false, true
end
def query_cache_enabled
query_cache.enabled
end
def dirties_query_cache
query_cache.dirties
end
def clear_query_cache
if @pinned_connection
# With transactional fixtures, and especially systems test
# another thread may use the same connection, but with a different
# query cache. So we must clear them all.
@thread_query_caches.each_value(&:clear)
else
query_cache.clear
end
end
private
def prune_thread_cache
dead_threads = @thread_query_caches.keys.reject(&:alive?)
dead_threads.each do |dead_thread|
@thread_query_caches.delete(dead_thread)
end
end
def query_cache
@thread_query_caches.compute_if_absent(ActiveSupport::IsolatedExecutionState.context) do
Store.new(@query_cache_max_size)
end
end
end
attr_accessor :query_cache
def initialize(*)
super
@query_cache = nil
end
def query_cache_enabled
@query_cache&.enabled?
end
# Enable the query cache within the block.
def cache(&block)
pool.enable_query_cache(&block)
end
def enable_query_cache!
pool.enable_query_cache!
end
# Disable the query cache within the block.
#
# Set <tt>dirties: false</tt> to prevent query caches on all connections from being cleared by write operations.
# (By default, write operations dirty all connections' query caches in case they are replicas whose cache would now be outdated.)
def uncached(dirties: true, &block)
pool.disable_query_cache(dirties: dirties, &block)
end
def disable_query_cache!
pool.disable_query_cache!
end
# Clears the query cache.
#
# One reason you may wish to call this method explicitly is between queries
# that ask the database to randomize results. Otherwise the cache would see
# the same SQL query and repeatedly return the same result each time, silently
# undermining the randomness you were expecting.
def clear_query_cache
pool.clear_query_cache
end
def select_all(arel, name = nil, binds = [], preparable: nil, async: false, allow_retry: false) # :nodoc:
arel = arel_from_relation(arel)
# If arel is locked this is a SELECT ... FOR UPDATE or somesuch.
# Such queries should not be cached.
if @query_cache&.enabled? && !(arel.respond_to?(:locked) && arel.locked)
sql, binds, preparable, allow_retry = to_sql_and_binds(arel, binds, preparable)
if async
result = lookup_sql_cache(sql, name, binds) || super(sql, name, binds, preparable: preparable, async: async, allow_retry: allow_retry)
FutureResult.wrap(result)
else
cache_sql(sql, name, binds) { super(sql, name, binds, preparable: preparable, async: async, allow_retry: allow_retry) }
end
else
super
end
end
private
def unset_query_cache!
@query_cache = nil
end
def lookup_sql_cache(sql, name, binds)
key = binds.empty? ? sql : [sql, binds]
result = nil
@lock.synchronize do
result = @query_cache[key]
end
if result
ActiveSupport::Notifications.instrument(
"sql.active_record",
cache_notification_info(sql, name, binds)
)
end
result
end
def cache_sql(sql, name, binds)
key = binds.empty? ? sql : [sql, binds]
result = nil
hit = true
@lock.synchronize do
result = @query_cache.compute_if_absent(key) do
hit = false
yield
end
end
if hit
ActiveSupport::Notifications.instrument(
"sql.active_record",
cache_notification_info(sql, name, binds)
)
end
result.dup
end
# Database adapters can override this method to
# provide custom cache information.
def cache_notification_info(sql, name, binds)
{
sql: sql,
binds: binds,
type_casted_binds: -> { type_casted_binds(binds) },
name: name,
connection: self,
cached: true
}
end
end
end
end