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comparison src/share/vm/memory/gcLocker.cpp @ 0:a61af66fc99e jdk7-b24

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author duke
date Sat, 01 Dec 2007 00:00:00 +0000
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children c0492d52d55b
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-1:000000000000 0:a61af66fc99e
1 /*
2 * Copyright 1997-2007 Sun Microsystems, Inc. All Rights Reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
20 * CA 95054 USA or visit www.sun.com if you need additional information or
21 * have any questions.
22 *
23 */
24
25 # include "incls/_precompiled.incl"
26 # include "incls/_gcLocker.cpp.incl"
27
28 volatile jint GC_locker::_jni_lock_count = 0;
29 volatile jint GC_locker::_lock_count = 0;
30 volatile bool GC_locker::_needs_gc = false;
31 volatile bool GC_locker::_doing_gc = false;
32
33 void GC_locker::stall_until_clear() {
34 assert(!JavaThread::current()->in_critical(), "Would deadlock");
35 MutexLocker ml(JNICritical_lock);
36 // Wait for _needs_gc to be cleared
37 while (GC_locker::needs_gc()) {
38 JNICritical_lock->wait();
39 }
40 }
41
42 void GC_locker::jni_lock_slow() {
43 MutexLocker mu(JNICritical_lock);
44 // Block entering threads if we know at least one thread is in a
45 // JNI critical region and we need a GC.
46 // We check that at least one thread is in a critical region before
47 // blocking because blocked threads are woken up by a thread exiting
48 // a JNI critical region.
49 while ((is_jni_active() && needs_gc()) || _doing_gc) {
50 JNICritical_lock->wait();
51 }
52 jni_lock();
53 }
54
55 void GC_locker::jni_unlock_slow() {
56 MutexLocker mu(JNICritical_lock);
57 jni_unlock();
58 if (needs_gc() && !is_jni_active()) {
59 // We're the last thread out. Cause a GC to occur.
60 // GC will also check is_active, so this check is not
61 // strictly needed. It's added here to make it clear that
62 // the GC will NOT be performed if any other caller
63 // of GC_locker::lock() still needs GC locked.
64 if (!is_active()) {
65 _doing_gc = true;
66 {
67 // Must give up the lock while at a safepoint
68 MutexUnlocker munlock(JNICritical_lock);
69 Universe::heap()->collect(GCCause::_gc_locker);
70 }
71 _doing_gc = false;
72 }
73 clear_needs_gc();
74 JNICritical_lock->notify_all();
75 }
76 }
77
78 // Implementation of No_GC_Verifier
79
80 #ifdef ASSERT
81
82 No_GC_Verifier::No_GC_Verifier(bool verifygc) {
83 _verifygc = verifygc;
84 if (_verifygc) {
85 CollectedHeap* h = Universe::heap();
86 assert(!h->is_gc_active(), "GC active during No_GC_Verifier");
87 _old_invocations = h->total_collections();
88 }
89 }
90
91
92 No_GC_Verifier::~No_GC_Verifier() {
93 if (_verifygc) {
94 CollectedHeap* h = Universe::heap();
95 assert(!h->is_gc_active(), "GC active during No_GC_Verifier");
96 if (_old_invocations != h->total_collections()) {
97 fatal("collection in a No_GC_Verifier secured function");
98 }
99 }
100 }
101
102 Pause_No_GC_Verifier::Pause_No_GC_Verifier(No_GC_Verifier * ngcv) {
103 _ngcv = ngcv;
104 if (_ngcv->_verifygc) {
105 // if we were verifying, then make sure that nothing is
106 // wrong before we "pause" verification
107 CollectedHeap* h = Universe::heap();
108 assert(!h->is_gc_active(), "GC active during No_GC_Verifier");
109 if (_ngcv->_old_invocations != h->total_collections()) {
110 fatal("collection in a No_GC_Verifier secured function");
111 }
112 }
113 }
114
115
116 Pause_No_GC_Verifier::~Pause_No_GC_Verifier() {
117 if (_ngcv->_verifygc) {
118 // if we were verifying before, then reenable verification
119 CollectedHeap* h = Universe::heap();
120 assert(!h->is_gc_active(), "GC active during No_GC_Verifier");
121 _ngcv->_old_invocations = h->total_collections();
122 }
123 }
124
125
126 // JRT_LEAF rules:
127 // A JRT_LEAF method may not interfere with safepointing by
128 // 1) acquiring or blocking on a Mutex or JavaLock - checked
129 // 2) allocating heap memory - checked
130 // 3) executing a VM operation - checked
131 // 4) executing a system call (including malloc) that could block or grab a lock
132 // 5) invoking GC
133 // 6) reaching a safepoint
134 // 7) running too long
135 // Nor may any method it calls.
136 JRT_Leaf_Verifier::JRT_Leaf_Verifier()
137 : No_Safepoint_Verifier(true, JRT_Leaf_Verifier::should_verify_GC())
138 {
139 }
140
141 JRT_Leaf_Verifier::~JRT_Leaf_Verifier()
142 {
143 }
144
145 bool JRT_Leaf_Verifier::should_verify_GC() {
146 switch (JavaThread::current()->thread_state()) {
147 case _thread_in_Java:
148 // is in a leaf routine, there must be no safepoint.
149 return true;
150 case _thread_in_native:
151 // A native thread is not subject to safepoints.
152 // Even while it is in a leaf routine, GC is ok
153 return false;
154 default:
155 // Leaf routines cannot be called from other contexts.
156 ShouldNotReachHere();
157 return false;
158 }
159 }
160 #endif