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/*
* Copyright (c) 2005, Eric Crahen
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is furnished
* to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*
*/
#ifndef __ZTBLOCKINGSTATE_H__
#define __ZTBLOCKINGSTATE_H__
#include <assert.h>
namespace ZThread {
/**
* @class Status
* @version 2.3.0
*
* A Status is associated with each Thread's Monitor. Monitors rely on a
* Status object for providing information that will affect a blocking operations.
*/
class Status {
public:
//! Aggregate of pending status changes
volatile unsigned short _pending;
//! Interest mask
volatile unsigned short _mask;
public:
//! State for the monitor
typedef enum {
// Default
INVALID = 0x00,
// Valid states
SIGNALED = 0x01,
INTERRUPTED = 0x02,
TIMEDOUT = 0x04,
CANCELED = 0x08,
// Mask
ANYTHING = (~INVALID & ~CANCELED)
} STATE;
Status() : _pending((unsigned short)INVALID), _mask((unsigned short)ANYTHING) { }
/**
* Set the mask for the STATE's that next() will report.
* STATE's not covered by the interest mask can still be
* set, they just aren't reported until the mask is changed
* to cover that STATE.
*
* @param STATE
* @pre accessed ONLY by the owning thread.
*/
void interest(STATE mask) {
_mask = static_cast<unsigned short>(mask);
}
bool masked(STATE mask) {
return (_mask & static_cast<unsigned short>(mask)) == 0;
}
/**
* Return true if next() will return a STATE covered
* by the current interest mask and by the mask given
* to this function.
*
* @param unsigned short
* @pre accessed ONLY by the owning thread.
*/
bool pending(unsigned short mask) {
assert(mask != INVALID);
return ((_pending & _mask) & mask) != INVALID;
}
/**
* Check the state without the interest mask.
*
* @param state
* @return true if the flag is set
* @pre access must be serial
*/
bool examine(STATE state) {
return (_pending & static_cast<unsigned short>(state)) != INVALID;
}
/**
* Add the flags to the current state.
*
* @param interest - the flags to add to the current state.
* @pre access must be serial
*/
void push(STATE interest) {
_pending |= interest;
}
/**
* Clear the flags from the current state
*
* @param interest - the flags to clear from the current state.
* @pre access must be serial
*/
void clear(STATE interest) {
assert(interest != INVALID);
assert(interest != ANYTHING);
assert(interest != CANCELED);
_pending &= ~interest;
}
/**
* Get the next state from set that has accumulated. The order STATES are
* reported in is SIGNALED, TIMEOUT, or INTERRUPTED. Setting the
* intrest mask allows certain state to be selectively ignored for
* a time - but not lost. The states will become visible again as soon
* as the interest mask is changed appropriately. The interest mask is
* generally used to create uninterruptable waits (waiting for threads
* to start, reacquiring a conditions predicate lock, etc)
*
* @return STATE
* @pre access must be serial
*/
STATE next() {
STATE state = INVALID;
if(((_pending & _mask) & SIGNALED) != 0) {
// Absorb the timeout if it happens when a signal
// is available at the same time
_pending &= ~(SIGNALED|TIMEDOUT);
state = SIGNALED;
} else if(((_pending & _mask) & TIMEDOUT) != 0) {
_pending &= ~TIMEDOUT;
state = TIMEDOUT;
} else if(((_pending & _mask) & INTERRUPTED) != 0) {
_pending &= ~INTERRUPTED;
state = INTERRUPTED;
}
assert(state != INVALID);
return state;
}
};
}; // namespace ZThread
#endif
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