jdk8-mips64-public/hotspot: comparison src/share/vm/runtime/park.cpp

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+:f90c822e73f8
+/*
+* 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);
+}

Mercurial > jdk8-mips64-public > hotspot / file comparison

comparison: src/share/vm/runtime/park.cpp

src/share/vm/runtime/park.cpp