class Monitor - monitor: Ruby Standard Library Documentation

# class Monitor

Use the `Monitor` class when you want to have a lock object for blocks with mutual exclusion.

    require 'monitor'

    lock = Monitor.new
    lock.synchronize do
      # exclusive access
    end

### Public Instance Methods

enter → nil click to toggle source

Enters exclusive section.

    static VALUE
    monitor_enter(VALUE monitor)
    {
        struct rb_monitor *mc = monitor_ptr(monitor);
        if (!mc_owner_p(mc)) {
            rb_mutex_lock(mc->mutex);
            RB_OBJ_WRITE(monitor, &mc->owner, rb_fiber_current());
            mc->count = 0;
        }
        mc->count++;
        return Qnil;
    }

Also aliased as: mon_enter
exit → nil click to toggle source

Leaves exclusive section.

    static VALUE
    monitor_exit(VALUE monitor)
    {
        monitor_check_owner(monitor);

        struct rb_monitor *mc = monitor_ptr(monitor);

        if (mc->count <= 0) rb_bug("monitor_exit: count:%d", (int)mc->count);
        mc->count--;

        if (mc->count == 0) {
            RB_OBJ_WRITE(monitor, &mc->owner, Qnil);
            rb_mutex_unlock(mc->mutex);
        }
        return Qnil;
    }

Also aliased as: mon_exit
mon_enter()
Alias for: enter
mon_exit()
Alias for: exit
mon_synchronize()
Alias for: synchronize
mon_try_enter()
Alias for: try_enter
new_cond() click to toggle source

Creates a new `MonitorMixin::ConditionVariable` associated with the `Monitor` object.

    # File monitor/lib/monitor.rb, line 263
    def new_cond
      ::MonitorMixin::ConditionVariable.new(self)
    end

synchronize { } → result of the block click to toggle source

Enters exclusive section and executes the block. Leaves the exclusive section automatically when the block exits. See example under `MonitorMixin`.

    static VALUE
    monitor_synchronize(VALUE monitor)
    {
        monitor_enter(monitor);
        return rb_ensure(monitor_sync_body, monitor, monitor_sync_ensure, monitor);
    }

Also aliased as: mon_synchronize
try_enter → true or false click to toggle source

Attempts to enter exclusive section. Returns `false` if lock fails.

    static VALUE
    monitor_try_enter(VALUE monitor)
    {
        struct rb_monitor *mc = monitor_ptr(monitor);

        if (!mc_owner_p(mc)) {
            if (!rb_mutex_trylock(mc->mutex)) {
                return Qfalse;
            }
            RB_OBJ_WRITE(monitor, &mc->owner, rb_fiber_current());
            mc->count = 0;
        }
        mc->count += 1;
        return Qtrue;
    }

Also aliased as: try_mon_enter, mon_try_enter
try_mon_enter()

for compatibility

Alias for: try_enter