ÃæÊÔ¶àÏß³Ìͬ²½£¬Äã±ØÐëҪ˼¿¼µÄÎÊÌâ

static?final?class?FairSync?extends?Sync?{??final?void?lock()?{??acquire(1);??}??/**??*?Fair?version?of?tryAcquire.?Don't?grant?access?unless??*?recursive?call?or?no?waiters?or?is?first.??*/??protected?final?boolean?tryAcquire(int?acquires)?{??final?Thread?current?=?Thread.currentThread();??int?c?=?getState();??if?(c?==?0)?{??if?(!hasQueuedPredecessors()?&&??compareAndSetState(0,?acquires))?{??setExclusiveOwnerThread(current);??return?true;??}??}??else?if?(current?==?getExclusiveOwnerThread())?{??int?nextc?=?c?+?acquires;??if?(nextc?<?0)??throw?new?Error("Maximum?lock?count?exceeded");??setState(nextc);??return?true;??}??return?false;??}??}?

public?final?void?acquire(int?arg)?{??if?(!tryAcquire(arg)?&&??acquireQueued(addWaiter(Node.EXCLUSIVE),?arg))??selfInterrupt();??}?

public?static?void?park(Object?blocker)?{??Thread?t?=?Thread.currentThread();??setBlocker(t,?blocker);??UNSAFE.park(false,?0L);??setBlocker(t,?null);?}?

Unsafe_Park(JNIEnv?*env,?jobject?unsafe,?jboolean?isAbsolute,?jlong?time){?...?thread->parker()->park(isAbsolute?!=?0,?time);?...?}?

void?Parker::park(bool?isAbsolute,?jlong?time)?{??...??//»ñµÃµ±Ç°Ïß³Ì??Thread*?thread?=?Thread::current();??assert(thread->is_Java_thread(),?"Must?be?JavaThread");??JavaThread?*jt?=?(JavaThread?*)thread;??//Èç¹ûµ±Ç°Ï̱߳»ÉèÖÃÁËinterrupted±ê¼Ç£¬ÔòÖ±½Ó·µ»Ø??if?(Thread::is_interrupted(thread,?false))?{??return;??}??if?(time?>?0)?{??//unpacktimeÖиù¾ÝisAbsoluteµÄÖµÀ´Ìî³äabsTime½á¹¹Ì壬isAbsoluteΪtrueʱ£¬time´ú±í¾ø¶Ôʱ¼äÇÒµ¥Î»ÊǺÁÃ룬·ñÔòtimeÊÇÏà¶Ôʱ¼äÇÒµ¥Î»ÊÇÄÉÃë??//absTime.tvsec´ú±íÁ˶ÔÓÚʱ¼äµÄÃë??//absTime.tv_nsec´ú±í¶ÔӦʱ¼äµÄÄÉÃë??unpackTime(&absTime,?isAbsolute,?time);??}??//µ÷ÓÃmutex?trylock·½·¨??if?(Thread::is_interrupted(thread,?false)?||?pthread_mutex_trylock(_mutex)?!=?0)?{??return;??}??//_counterÊÇÒ»¸öÐí¿ÉµÄÊýÁ¿£¬¸úReentrantLockÀﶨÒåµÄÐí¿É±äÁ¿»ù±¾¶¼ÊÇÒ»¸öÔ­Àí¡£?unpack·½·¨µ÷ÓÃʱ»á½«_counter¸³ÖµÎª1¡£??//_counter>0´ú±íÒѾ­ÓÐÈ˵÷ÓÃÁËunpark£¬ËùÒÔ²»ÓÃ×èÈû??int?status?;??if?(_counter?>?0)?{?//?no?wait?needed??_counter?=?0;??//ÊÍ·ÅmutexËø??status?=?pthread_mutex_unlock(_mutex);??return;??}?//ÉèÖÃÏß³Ì״̬ΪCONDVAR_WAIT??OSThreadWaitState?osts(thread->osthread(),?false?/*?not?Object.wait()?*/);??...??//µÈ´ý??_cur_index?=?isAbsolute???ABS_INDEX?:?REL_INDEX;??pthread_cond_timedwait(&_cond[_cur_index],?_mutex,?&absTime);??...??//ÊÍ·ÅmutexËø??status?=?pthread_mutex_unlock(_mutex)?;?}?

?enum?ThreadState?{??ALLOCATED,?//?Memory?has?been?allocated?but?not?initialized??INITIALIZED,?//?The?thread?has?been?initialized?but?yet?started??RUNNABLE,?//?Has?been?started?and?is?runnable,?but?not?necessarily?running??MONITOR_WAIT,?//?Waiting?on?a?contended?monitor?lock??CONDVAR_WAIT,?//?Waiting?on?a?condition?variable??OBJECT_WAIT,?//?Waiting?on?an?Object.wait()?call??BREAKPOINTED,?//?Suspended?at?breakpoint??SLEEPING,?//?Thread.sleep()??ZOMBIE?//?All?done,?but?not?reclaimed?yet?};?

//pthread_mutex_tÊÇposixÖеĻ¥³âËø½á¹¹Ìå?int?__pthread_mutex_trylock?(mutex)??pthread_mutex_t?*mutex;?{??int?oldval;??pid_t?id?=?THREAD_GETMEM?(THREAD_SELF,?tid);?switch?(__builtin_expect?(PTHREAD_MUTEX_TYPE?(mutex),??PTHREAD_MUTEX_TIMED_NP))??{??case?PTHREAD_MUTEX_ERRORCHECK_NP:??case?PTHREAD_MUTEX_TIMED_NP:??case?PTHREAD_MUTEX_ADAPTIVE_NP:??/*?Normal?mutex.?*/??if?(lll_trylock?(mutex->__data.__lock)?!=?0)??break;??/*?Record?the?ownership.?*/??mutex->__data.__owner?=?id;??++mutex->__data.__nusers;??return?0;??}?}???//ÒÔÏ´úÂëÔÚlowlevellock.hÖÐ???#define?__lll_trylock(futex)?\??(atomic_compare_and_exchange_val_acq?(futex,?1,?0)?!=?0)??#define?lll_trylock(futex)?__lll_trylock?(&(futex))?

int?internal_function?attribute_hidden?__pthread_mutex_unlock_usercnt?(mutex,?decr)??pthread_mutex_t?*mutex;??int?decr;?{??if?(__builtin_expect?(type,?PTHREAD_MUTEX_TIMED_NP)??==?PTHREAD_MUTEX_TIMED_NP)??{??/*?Always?reset?the?owner?field.?*/??normal:??mutex->__data.__owner?=?0;??if?(decr)??/*?One?less?user.?*/??--mutex->__data.__nusers;??/*?Unlock.?*/??lll_unlock?(mutex->__data.__lock,?PTHREAD_MUTEX_PSHARED?(mutex));??return?0;??}??}?

?#define?__lll_unlock(futex,?private)?\??((void)?({?\??int?*__futex?=?(futex);?\??int?__val?=?atomic_exchange_rel?(__futex,?0);?\??\??if?(__builtin_expect?(__val?>?1,?0))?\??lll_futex_wake?(__futex,?1,?private);?\??}))?#define?lll_unlock(futex,?private)?__lll_unlock(&(futex),?private)?#define?lll_futex_wake(ftx,?nr,?private)?\?({?\??DO_INLINE_SYSCALL(futex,?3,?(long)?(ftx),?\??__lll_private_flag?(FUTEX_WAKE,?private),?\??(int)?(nr));?\??_r10?==?-1???-_retval?:?_retval;?\?})?

#define?__lll_lock(futex,?private)?\??((void)?({?\??int?*__futex?=?(futex);?\??if?(__builtin_expect?(atomic_compare_and_exchange_bool_acq?(__futex,?\??1,?0),?0))?\??{?\??if?(__builtin_constant_p?(private)?&&?(private)?==?LLL_PRIVATE)?\??__lll_lock_wait_private?(__futex);?\??else?\??__lll_lock_wait?(__futex,?private);?\??}?\??}))?#define?lll_lock(futex,?private)?__lll_lock?(&(futex),?private)?void?__lll_lock_wait_private?(int?*futex)?{?//µÚÒ»´Î½øÀ´µÄʱºòfutex==1,ËùÒÔ²»»á×ßÕâ¸öif??if?(*futex?==?2)??lll_futex_wait?(futex,?2,?LLL_PRIVATE);?//ÔÚÕâÀï»á°ÑfutexÉèÖóÉ2£¬²¢µ÷ÓÃfutex_waitÈõ±Ç°Ï̵߳ȴý??while?(atomic_exchange_acq?(futex,?2)?!=?0)??lll_futex_wait?(futex,?2,?LLL_PRIVATE);?}?

/*
* Ìáʾ£º¸ÃÐдúÂë¹ý³¤£¬ÏµÍ³×Ô¶¯×¢ÊͲ»½øÐиßÁÁ¡£Ò»¼ü¸´ÖÆ»áÒƳýϵͳעÊÍ 
* int?int?__pthread_cond_timedwait?(cond,?mutex,?abstime)??pthread_cond_t?*cond;??pthread_mutex_t?*mutex;??const?struct?timespec?*abstime;?{??struct?_pthread_cleanup_buffer?buffer;??struct?_condvar_cleanup_buffer?cbuffer;??int?result?=?0;??/*?Catch?invalid?parameters.?*/??if?(abstime->tv_nsec?<?0?||?abstime->tv_nsec?>=?1000000000)??return?EINVAL;??int?pshared?=?(cond->__data.__mutex?==?(void?*)?~0l)????LLL_SHARED?:?LLL_PRIVATE;??//1.»ñµÃcondËø??lll_lock?(cond->__data.__lock,?pshared);??//2.ÊÍ·ÅmutexËø??int?err?=?__pthread_mutex_unlock_usercnt?(mutex,?0);??if?(err)??{??lll_unlock?(cond->__data.__lock,?pshared);??return?err;??}??/*?We?have?one?new?user?of?the?condvar.?*/??//ÿִÐÐÒ»´Îwait(pthread_cond_timedwait/pthread_cond_wait)£¬__total_seq¾Í»á+1??++cond->__data.__total_seq;??//ÓÃÀ´Ö´ÐÐfutex_waitµÄ±äÁ¿??++cond->__data.__futex;??//±êʶ¸Ãcond»¹ÓжàÉÙÏß³ÌÔÚʹÓã¬pthread_cond_destroyÐèÒªµÈ´ýËùÓеIJÙ×÷Íê³É??cond->__data.__nwaiters?+=?1?<<?COND_NWAITERS_SHIFT;??/*?Remember?the?mutex?we?are?using?here.?If?there?is?already?a??different?address?store?this?is?a?bad?user?bug.?Do?not?store??anything?for?pshared?condvars.?*/??//±£´æmutexËø??if?(cond->__data.__mutex?!=?(void?*)?~0l)??cond->__data.__mutex?=?mutex;??/*?Prepare?structure?passed?to?cancellation?handler.?*/??cbuffer.cond?=?cond;??cbuffer.mutex?=?mutex;??/*?Before?we?block?we?enable?cancellation.?Therefore?we?have?to??install?a?cancellation?handler.?*/??__pthread_cleanup_push?(&buffer,?__condvar_cleanup,?&cbuffer);??/*?The?current?values?of?the?wakeup?counter.?The?"woken"?counter??must?exceed?this?value.?*/??//¼Ç¼futex_waitÇ°µÄ__wakeup_seq£¨Îª¸ÃcondÉÏÖ´ÐÐÁ˶àÉÙ´Îsign²Ù×÷+timeout´ÎÊý£©ºÍ__broadcast_seq£¨´ú±íÔÚ¸ÃcondÉÏÖ´ÐÐÁ˶àÉÙ´Îbroadcast£©??unsigned?long?long?int?val;??unsigned?long?long?int?seq;??val?=?seq?=?cond->__data.__wakeup_seq;??/*?Remember?the?broadcast?counter.?*/??cbuffer.bc_seq?=?cond->__data.__broadcast_seq;??while?(1)??{??//3.¼ÆËãÒªwaitµÄÏà¶Ôʱ¼ä??struct?timespec?rt;??{?#ifdef?__NR_clock_gettime??INTERNAL_SYSCALL_DECL?(err);??int?ret;??ret?=?INTERNAL_VSYSCALL?(clock_gettime,?err,?2,??(cond->__data.__nwaiters??&?((1?<<?COND_NWAITERS_SHIFT)?-?1)),??&rt);?#?ifndef?__ASSUME_POSIX_TIMERS??if?(__builtin_expect?(INTERNAL_SYSCALL_ERROR_P?(ret,?err),?0))??{??struct?timeval?tv;??(void)?gettimeofday?(&tv,?NULL);??/*?Convert?the?absolute?timeout?value?to?a?relative?timeout.?*/??rt.tv_sec?=?abstime->tv_sec?-?tv.tv_sec;??rt.tv_nsec?=?abstime->tv_nsec?-?tv.tv_usec?*?1000;??}??else?#?endif??{??/*?Convert?the?absolute?timeout?value?to?a?relative?timeout.?*/??rt.tv_sec?=?abstime->tv_sec?-?rt.tv_sec;??rt.tv_nsec?=?abstime->tv_nsec?-?rt.tv_nsec;??}?#else??/*?Get?the?current?time.?So?far?we?support?only?one?clock.?*/??struct?timeval?tv;??(void)?gettimeofday?(&tv,?NULL);??/*?Convert?the?absolute?timeout?value?to?a?relative?timeout.?*/??rt.tv_sec?=?abstime->tv_sec?-?tv.tv_sec;??rt.tv_nsec?=?abstime->tv_nsec?-?tv.tv_usec?*?1000;?#endif??}??if?(rt.tv_nsec?<?0)??{??rt.tv_nsec?+=?1000000000;??--rt.tv_sec;??}??/*---¼ÆËãÒªwaitµÄÏà¶Ôʱ¼ä?end----?*/??//ÊÇ·ñ³¬Ê±??/*?Did?we?already?time?out??*/??if?(__builtin_expect?(rt.tv_sec?<?0,?0))??{??//±»broadcast»½ÐÑ£¬ÕâÀïÒÉÎʵÄÊÇ£¬ÎªÊ²Ã´²»ÐèÒªÅжÏ__wakeup_seq£¿??if?(cbuffer.bc_seq?!=?cond->__data.__broadcast_seq)??goto?bc_out;??goto?timeout;??}??unsigned?int?futex_val?=?cond->__data.__futex;??//4.ÊÍ·ÅcondËø£¬×¼±¸wait??lll_unlock?(cond->__data.__lock,?pshared);??/*?Enable?asynchronous?cancellation.?Required?by?the?standard.?*/??cbuffer.oldtype?=?__pthread_enable_asynccancel?();??//5.µ÷ÓÃfutex_wait??/*?Wait?until?woken?by?signal?or?broadcast.?*/??err?=?lll_futex_timed_wait?(&cond->__data.__futex,??futex_val,?&rt,?pshared);??/*?Disable?asynchronous?cancellation.?*/??__pthread_disable_asynccancel?(cbuffer.oldtype);??//6.ÖØлñµÃcondËø£¬ÒòΪÓÖÒª·ÃÎÊ&ÐÞ¸ÄcondµÄÊý¾ÝÁË??lll_lock?(cond->__data.__lock,?pshared);??//__broadcast_seqÖµ·¢Éú¸Ä±ä£¬´ú±í·¢ÉúÁËÓÐÏ̵߳÷ÓÃÁ˹㲥??if?(cbuffer.bc_seq?!=?cond->__data.__broadcast_seq)??goto?bc_out;??//ÅжÏÊÇ·ñÊDZ»sign»½Ðѵģ¬sign»áÔö¼Ó__wakeup_seq??//µÚ¶þ¸öÌõ¼þcond->__data.__woken_seq?!=?valµÄÒâÒåÔÚÓÚ??//¿ÉÄÜÁ½¸öÏß³ÌA¡¢BÔÚwait£¬Ò»¸öÏ̵߳÷ÓÃÁËsignµ¼ÖÂA±»»½ÐÑ£¬ÕâʱBÒòΪ³¬Ê±±»»½ÐÑ??//¶ÔÓÚBÏß³ÌÀ´Ëµ£¬Ö´Ðе½ÕâÀïʱµÚÒ»¸öÌõ¼þÒ²ÊÇÂú×ãµÄ£¬´Ó¶øµ¼ÖÂÉϲãÄõ½µÄresult²»Êdz¬Ê±??//ËùÒÔÕâÀïÐèÒªÅжÏÏÂ__woken_seq£¨¼´¸ÃcondÒѾ­±»»½ÐѵÄÏß³ÌÊý£©ÊÇ·ñµÈÓÚ__wakeup_seq£¨signÖ´ÐдÎÊý+timeout´ÎÊý£©??val?=?cond->__data.__wakeup_seq;??if?(val?!=?seq?&&?cond->__data.__woken_seq?!=?val)??break;??/*?Not?woken?yet.?Maybe?the?time?expired??*/??if?(__builtin_expect?(err?==?-ETIMEDOUT,?0))??{??timeout:??/*?Yep.?Adjust?the?counters.?*/??++cond->__data.__wakeup_seq;??++cond->__data.__futex;??/*?The?error?value.?*/??result?=?ETIMEDOUT;??break;??}??}??//Ò»¸öÏß³ÌÒѾ­ÐÑÁËËùÒÔÕâÀï__woken_seq?+1??++cond->__data.__woken_seq;??bc_out:??//??cond->__data.__nwaiters?-=?1?<<?COND_NWAITERS_SHIFT;??/*?If?pthread_cond_destroy?was?called?on?this?variable?already,??notify?the?pthread_cond_destroy?caller?all?waiters?have?left??and?it?can?be?successfully?destroyed.?*/??if?(cond->__data.__total_seq?==?-1ULL??&&?cond->__data.__nwaiters?<?(1?<<?COND_NWAITERS_SHIFT))??lll_futex_wake?(&cond->__data.__nwaiters,?1,?pshared);??//9.condÊý¾ÝÐÞ¸ÄÍê±Ï£¬ÊÍ·ÅËø??lll_unlock?(cond->__data.__lock,?pshared);??/*?The?cancellation?handling?is?back?to?normal,?remove?the?handler.?*/??__pthread_cleanup_pop?(&buffer,?0);??//10.ÖØлñµÃmutexËø??err?=?__pthread_mutex_cond_lock?(mutex);??return?err??:?result;?}
*/

Object?condObj=new?Object();?voilate?int?flag?=?0;?public?void?waitTest(){??if(flag?==?0){??condObj.wait();??}?}?public?void?notifyTest(){??flag=1;??condObj.notify();?}?

Object?condObj=new?Object();?voilate?int?flag?=?0;?public?void?waitTest(){??synchronized(condObj){??if(flag?==?0){??condObj.wait();??}??}?}?public?void?notifyTest(){??synchronized(condObj){??flag=1;??condObj.notify();??}?}?

int?__pthread_cond_signal?(cond)??pthread_cond_t?*cond;?{??int?pshared?=?(cond->__data.__mutex?==?(void?*)?~0l)????LLL_SHARED?:?LLL_PRIVATE;??//ÒòΪҪ²Ù×÷condµÄÊý¾Ý£¬ËùÒÔÒª¼ÓËø??lll_lock?(cond->__data.__lock,?pshared);??/*?Are?there?any?waiters?to?be?woken??*/??if?(cond->__data.__total_seq?>?cond->__data.__wakeup_seq)??{??//__wakeup_seqΪִÐÐsignÓëtimeout´ÎÊýµÄºÍ??++cond->__data.__wakeup_seq;??++cond->__data.__futex;??...??//»½ÐÑwaitµÄÏß³Ì??lll_futex_wake?(&cond->__data.__futex,?1,?pshared);??}??/*?We?are?done.?*/??lll_unlock?(cond->__data.__lock,?pshared);??return?0;?}?