diff options
Diffstat (limited to 'activesupport/lib/active_support/concurrency/share_lock.rb')
-rw-r--r-- | activesupport/lib/active_support/concurrency/share_lock.rb | 81 |
1 files changed, 60 insertions, 21 deletions
diff --git a/activesupport/lib/active_support/concurrency/share_lock.rb b/activesupport/lib/active_support/concurrency/share_lock.rb index 54244317e4..4318523b07 100644 --- a/activesupport/lib/active_support/concurrency/share_lock.rb +++ b/activesupport/lib/active_support/concurrency/share_lock.rb @@ -1,5 +1,5 @@ -require 'thread' -require 'monitor' +require "thread" +require "monitor" module ActiveSupport module Concurrency @@ -13,6 +13,37 @@ module ActiveSupport # we need exclusive locks to be reentrant, and we need to be able # to upgrade share locks to exclusive. + def raw_state # :nodoc: + synchronize do + threads = @sleeping.keys | @sharing.keys | @waiting.keys + threads |= [@exclusive_thread] if @exclusive_thread + + data = {} + + threads.each do |thread| + purpose, compatible = @waiting[thread] + + data[thread] = { + thread: thread, + sharing: @sharing[thread], + exclusive: @exclusive_thread == thread, + purpose: purpose, + compatible: compatible, + waiting: !!@waiting[thread], + sleeper: @sleeping[thread], + } + end + + # NB: Yields while holding our *internal* synchronize lock, + # which is supposed to be used only for a few instructions at + # a time. This allows the caller to inspect additional state + # without things changing out from underneath, but would have + # disastrous effects upon normal operation. Fortunately, this + # method is only intended to be called when things have + # already gone wrong. + yield data + end + end def initialize super() @@ -21,6 +52,7 @@ module ActiveSupport @sharing = Hash.new(0) @waiting = {} + @sleeping = {} @exclusive_thread = nil @exclusive_depth = 0 end @@ -46,7 +78,7 @@ module ActiveSupport return false if no_wait yield_shares(purpose: purpose, compatible: compatible, block_share: true) do - @cv.wait_while { busy_for_exclusive?(purpose) } + wait_for(:start_exclusive) { busy_for_exclusive?(purpose) } end end @exclusive_thread = Thread.current @@ -69,7 +101,7 @@ module ActiveSupport if eligible_waiters?(compatible) yield_shares(compatible: compatible, block_share: true) do - @cv.wait_while { @exclusive_thread || eligible_waiters?(compatible) } + wait_for(:stop_exclusive) { @exclusive_thread || eligible_waiters?(compatible) } end end @cv.broadcast @@ -84,11 +116,11 @@ module ActiveSupport elsif @waiting[Thread.current] # We're nested inside a +yield_shares+ call: we'll resume as # soon as there isn't an exclusive lock in our way - @cv.wait_while { @exclusive_thread } + wait_for(:start_sharing) { @exclusive_thread } else # This is an initial / outermost share call: any outstanding # requests for an exclusive lock get to go first - @cv.wait_while { busy_for_sharing?(false) } + wait_for(:start_sharing) { busy_for_sharing?(false) } end @sharing[Thread.current] += 1 end @@ -144,16 +176,16 @@ module ActiveSupport end compatible |= [false] unless block_share @waiting[Thread.current] = [purpose, compatible] - - @cv.broadcast end + + @cv.broadcast end begin yield ensure synchronize do - @cv.wait_while { @exclusive_thread && @exclusive_thread != Thread.current } + wait_for(:yield_shares) { @exclusive_thread && @exclusive_thread != Thread.current } if previous_wait @waiting[Thread.current] = previous_wait @@ -167,20 +199,27 @@ module ActiveSupport private - # Must be called within synchronize - def busy_for_exclusive?(purpose) - busy_for_sharing?(purpose) || - @sharing.size > (@sharing[Thread.current] > 0 ? 1 : 0) - end + # Must be called within synchronize + def busy_for_exclusive?(purpose) + busy_for_sharing?(purpose) || + @sharing.size > (@sharing[Thread.current] > 0 ? 1 : 0) + end - def busy_for_sharing?(purpose) - (@exclusive_thread && @exclusive_thread != Thread.current) || - @waiting.any? { |t, (_, c)| t != Thread.current && !c.include?(purpose) } - end + def busy_for_sharing?(purpose) + (@exclusive_thread && @exclusive_thread != Thread.current) || + @waiting.any? { |t, (_, c)| t != Thread.current && !c.include?(purpose) } + end - def eligible_waiters?(compatible) - @waiting.any? { |t, (p, _)| compatible.include?(p) && @waiting.all? { |t2, (_, c2)| t == t2 || c2.include?(p) } } - end + def eligible_waiters?(compatible) + @waiting.any? { |t, (p, _)| compatible.include?(p) && @waiting.all? { |t2, (_, c2)| t == t2 || c2.include?(p) } } + end + + def wait_for(method) + @sleeping[Thread.current] = method + @cv.wait_while { yield } + ensure + @sleeping.delete Thread.current + end end end end |