Class: FSDB::Modex
- Inherits:
-
Object
- Object
- FSDB::Modex
- Defined in:
- lib/fsdb/modex.rb
Overview
Modex is a modal exclusion semaphore. The two modes are shared (SH) and exclusive (EX). Modex is not nestable.
Defined Under Namespace
Modules: ForkSafely
Constant Summary collapse
- SH =
:SH
- EX =
:EX
Instance Method Summary collapse
-
#initialize ⇒ Modex
constructor
A new instance of Modex.
-
#lock(mode) ⇒ Object
the block is executed in the exclusive context.
-
#remove_dead ⇒ Object
:nodoc:.
- #synchronize(mode, do_when_first = nil, do_when_last = nil, arg = nil) ⇒ Object
- #try_lock(mode) ⇒ Object
-
#unlock ⇒ Object
the block is executed in the exclusive context.
Constructor Details
#initialize ⇒ Modex
Returns a new instance of Modex.
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# File 'lib/fsdb/modex.rb', line 11 def initialize @waiting = [] @locked = [] @mode = nil @first = true @m = Mutex.new end |
Instance Method Details
#lock(mode) ⇒ Object
the block is executed in the exclusive context
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# File 'lib/fsdb/modex.rb', line 38 def lock mode @m.synchronize do thread = Thread.current raise ThreadError, "nesting not allowed" if @locked.include?(thread) if @mode == mode and mode == SH and @waiting.empty? # strict queue @locked << thread elsif not @mode @mode = mode @locked << thread else @waiting << thread << mode @m.unlock Thread.stop @m.lock end yield if block_given? # if @mode != mode # raise "@mode == #{@mode} but mode == #{mode}" # end # # if @mode == EX and @locked.size > 1 # raise "@mode == EX but @locked.size == #{@locked.size}" # end self end end |
#remove_dead ⇒ Object
:nodoc:
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# File 'lib/fsdb/modex.rb', line 125 def remove_dead # :nodoc: @m.synchronize do waiting = @waiting; @waiting = [] until waiting.empty? t = waiting.shift; m = waiting.shift @waiting << t << m if t.alive? end @locked = @locked.select {|t| t.alive?} wake_next_waiter if @locked.empty? end end |
#synchronize(mode, do_when_first = nil, do_when_last = nil, arg = nil) ⇒ Object
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# File 'lib/fsdb/modex.rb', line 91 def synchronize mode, do_when_first = nil, do_when_last = nil, arg = nil lock mode do if @first @first = false if do_when_first if mode == SH @mode = EX end nonexclusive { do_when_first[arg] } if mode == SH @mode = SH wake_waiting_sharers end end end end yield ensure unlock do if @locked.size == 1 if do_when_last @mode = EX nonexclusive { do_when_last[arg] } end @first = true end end end |
#try_lock(mode) ⇒ Object
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# File 'lib/fsdb/modex.rb', line 19 def try_lock mode @m.synchronize do thread = Thread.current raise ThreadError, "nesting not allowed" if @locked.include?(thread) if @mode == mode and mode == SH and @waiting.empty? # strict queue @locked << thread true elsif not @mode @mode = mode @locked << thread true else false end end end |
#unlock ⇒ Object
the block is executed in the exclusive context
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# File 'lib/fsdb/modex.rb', line 70 def unlock raise ThreadError, "already unlocked" unless @mode @m.synchronize do if block_given? begin yield ensure @locked.delete Thread.current end else @locked.delete Thread.current end wake_next_waiter if @locked.empty? end self end |