diff -r 000000000000 -r f90c822e73f8 src/share/vm/runtime/park.cpp --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/src/share/vm/runtime/park.cpp Wed Apr 27 01:25:04 2016 +0800 @@ -0,0 +1,168 @@ +/* + * Copyright (c) 1997, 2013, Oracle and/or its affiliates. All rights reserved. + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. + * + * This code is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License version 2 only, as + * published by the Free Software Foundation. + * + * This code is distributed in the hope that it will be useful, but WITHOUT + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License + * version 2 for more details (a copy is included in the LICENSE file that + * accompanied this code). + * + * You should have received a copy of the GNU General Public License version + * 2 along with this work; if not, write to the Free Software Foundation, + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. + * + * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA + * or visit www.oracle.com if you need additional information or have any + * questions. + * + */ + +#include "precompiled.hpp" +#include "runtime/thread.hpp" + + + +// Lifecycle management for TSM ParkEvents. +// ParkEvents are type-stable (TSM). +// In our particular implementation they happen to be immortal. +// +// We manage concurrency on the FreeList with a CAS-based +// detach-modify-reattach idiom that avoids the ABA problems +// that would otherwise be present in a simple CAS-based +// push-pop implementation. (push-one and pop-all) +// +// Caveat: Allocate() and Release() may be called from threads +// other than the thread associated with the Event! +// If we need to call Allocate() when running as the thread in +// question then look for the PD calls to initialize native TLS. +// Native TLS (Win32/Linux/Solaris) can only be initialized or +// accessed by the associated thread. +// See also pd_initialize(). +// +// Note that we could defer associating a ParkEvent with a thread +// until the 1st time the thread calls park(). unpark() calls to +// an unprovisioned thread would be ignored. The first park() call +// for a thread would allocate and associate a ParkEvent and return +// immediately. + +volatile int ParkEvent::ListLock = 0 ; +ParkEvent * volatile ParkEvent::FreeList = NULL ; + +ParkEvent * ParkEvent::Allocate (Thread * t) { + // In rare cases -- JVM_RawMonitor* operations -- we can find t == null. + ParkEvent * ev ; + + // Start by trying to recycle an existing but unassociated + // ParkEvent from the global free list. + // Using a spin lock since we are part of the mutex impl. + // 8028280: using concurrent free list without memory management can leak + // pretty badly it turns out. + Thread::SpinAcquire(&ListLock, "ParkEventFreeListAllocate"); + { + ev = FreeList; + if (ev != NULL) { + FreeList = ev->FreeNext; + } + } + Thread::SpinRelease(&ListLock); + + if (ev != NULL) { + guarantee (ev->AssociatedWith == NULL, "invariant") ; + } else { + // Do this the hard way -- materialize a new ParkEvent. + ev = new ParkEvent () ; + guarantee ((intptr_t(ev) & 0xFF) == 0, "invariant") ; + } + ev->reset() ; // courtesy to caller + ev->AssociatedWith = t ; // Associate ev with t + ev->FreeNext = NULL ; + return ev ; +} + +void ParkEvent::Release (ParkEvent * ev) { + if (ev == NULL) return ; + guarantee (ev->FreeNext == NULL , "invariant") ; + ev->AssociatedWith = NULL ; + // Note that if we didn't have the TSM/immortal constraint, then + // when reattaching we could trim the list. + Thread::SpinAcquire(&ListLock, "ParkEventFreeListRelease"); + { + ev->FreeNext = FreeList; + FreeList = ev; + } + Thread::SpinRelease(&ListLock); +} + +// Override operator new and delete so we can ensure that the +// least significant byte of ParkEvent addresses is 0. +// Beware that excessive address alignment is undesirable +// as it can result in D$ index usage imbalance as +// well as bank access imbalance on Niagara-like platforms, +// although Niagara's hash function should help. + +void * ParkEvent::operator new (size_t sz) throw() { + return (void *) ((intptr_t (AllocateHeap(sz + 256, mtInternal, CALLER_PC)) + 256) & -256) ; +} + +void ParkEvent::operator delete (void * a) { + // ParkEvents are type-stable and immortal ... + ShouldNotReachHere(); +} + + +// 6399321 As a temporary measure we copied & modified the ParkEvent:: +// allocate() and release() code for use by Parkers. The Parker:: forms +// will eventually be removed as we consolide and shift over to ParkEvents +// for both builtin synchronization and JSR166 operations. + +volatile int Parker::ListLock = 0 ; +Parker * volatile Parker::FreeList = NULL ; + +Parker * Parker::Allocate (JavaThread * t) { + guarantee (t != NULL, "invariant") ; + Parker * p ; + + // Start by trying to recycle an existing but unassociated + // Parker from the global free list. + // 8028280: using concurrent free list without memory management can leak + // pretty badly it turns out. + Thread::SpinAcquire(&ListLock, "ParkerFreeListAllocate"); + { + p = FreeList; + if (p != NULL) { + FreeList = p->FreeNext; + } + } + Thread::SpinRelease(&ListLock); + + if (p != NULL) { + guarantee (p->AssociatedWith == NULL, "invariant") ; + } else { + // Do this the hard way -- materialize a new Parker.. + p = new Parker() ; + } + p->AssociatedWith = t ; // Associate p with t + p->FreeNext = NULL ; + return p ; +} + + +void Parker::Release (Parker * p) { + if (p == NULL) return ; + guarantee (p->AssociatedWith != NULL, "invariant") ; + guarantee (p->FreeNext == NULL , "invariant") ; + p->AssociatedWith = NULL ; + + Thread::SpinAcquire(&ListLock, "ParkerFreeListRelease"); + { + p->FreeNext = FreeList; + FreeList = p; + } + Thread::SpinRelease(&ListLock); +} +