| /* |
| * 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 consolidate 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); |
| } |
| |