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Preserve reentrant lock state after invalid release #1112

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Preserve reentrant lock state after invalid release #1112

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14 changes: 8 additions & 6 deletions lib/concurrent-ruby/concurrent/atomic/reentrant_read_write_lock.rb
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Original file line number Diff line number Diff line change
Expand Up @@ -241,16 +241,17 @@ def try_read_lock
#
# @return [Boolean] true if the lock is successfully released
def release_read_lock
held = @HeldCount.value = @HeldCount.value - 1
held = @HeldCount.value
raise IllegalOperationError, "Cannot release a read lock which is not held" if held & READ_LOCK_MASK == 0

held = @HeldCount.value = held - 1
rlocks_held = held & READ_LOCK_MASK
if rlocks_held == 0
c = @Counter.update { |counter| counter - 1 }
# If one or more writers were waiting, and we were the last reader, wake a writer up
if waiting_or_running_writer?(c) && running_readers(c) == 0
@WriteQueue.signal
end
elsif rlocks_held == READ_LOCK_MASK
raise IllegalOperationError, "Cannot release a read lock which is not held"
end
true
end
Expand Down Expand Up @@ -334,14 +335,15 @@ def try_write_lock
#
# @return [Boolean] true if the lock is successfully released
def release_write_lock
held = @HeldCount.value = @HeldCount.value - WRITE_LOCK_HELD
held = @HeldCount.value
raise IllegalOperationError, "Cannot release a write lock which is not held" if held & WRITE_LOCK_MASK == 0

held = @HeldCount.value = held - WRITE_LOCK_HELD
wlocks_held = held & WRITE_LOCK_MASK
if wlocks_held == 0
c = @Counter.update { |counter| counter - RUNNING_WRITER }
@ReadQueue.broadcast
@WriteQueue.signal if waiting_writers(c) > 0
elsif wlocks_held == WRITE_LOCK_MASK
raise IllegalOperationError, "Cannot release a write lock which is not held"
end
true
end
Expand Down