Mercurial > hg > truffle
annotate src/share/vm/memory/gcLocker.hpp @ 21791:cd36556e1b78
Remove conditional makefile-based compilation of jvmci from mx_graal.py
author | Stefan Anzinger <stefan.anzinger@oracle.com> |
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date | Mon, 08 Jun 2015 14:25:25 +0200 |
parents | 52b4284cb496 |
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rev | line source |
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0 | 1 /* |
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2 * Copyright (c) 1997, 2013, Oracle and/or its affiliates. All rights reserved. |
0 | 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 * | |
1552
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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20 * or visit www.oracle.com if you need additional information or have any |
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21 * questions. |
0 | 22 * |
23 */ | |
24 | |
1972 | 25 #ifndef SHARE_VM_MEMORY_GCLOCKER_HPP |
26 #define SHARE_VM_MEMORY_GCLOCKER_HPP | |
27 | |
28 #include "gc_interface/collectedHeap.hpp" | |
29 #include "memory/genCollectedHeap.hpp" | |
30 #include "memory/universe.hpp" | |
31 #include "oops/oop.hpp" | |
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32 #include "runtime/thread.inline.hpp" |
1972 | 33 #ifdef TARGET_OS_FAMILY_linux |
34 # include "os_linux.inline.hpp" | |
35 #endif | |
36 #ifdef TARGET_OS_FAMILY_solaris | |
37 # include "os_solaris.inline.hpp" | |
38 #endif | |
39 #ifdef TARGET_OS_FAMILY_windows | |
40 # include "os_windows.inline.hpp" | |
41 #endif | |
3960 | 42 #ifdef TARGET_OS_FAMILY_bsd |
43 # include "os_bsd.inline.hpp" | |
44 #endif | |
1972 | 45 |
0 | 46 // The direct lock/unlock calls do not force a collection if an unlock |
47 // decrements the count to zero. Avoid calling these if at all possible. | |
48 | |
49 class GC_locker: public AllStatic { | |
50 private: | |
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51 // The _jni_lock_count keeps track of the number of threads that are |
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52 // currently in a critical region. It's only kept up to date when |
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53 // _needs_gc is true. The current value is computed during |
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54 // safepointing and decremented during the slow path of GC_locker |
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55 // unlocking. |
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56 static volatile jint _jni_lock_count; // number of jni active instances. |
0 | 57 static volatile bool _needs_gc; // heap is filling, we need a GC |
58 // note: bool is typedef'd as jint | |
59 static volatile bool _doing_gc; // unlock_critical() is doing a GC | |
60 | |
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61 #ifdef ASSERT |
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62 // This lock count is updated for all operations and is used to |
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63 // validate the jni_lock_count that is computed during safepoints. |
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64 static volatile jint _debug_jni_lock_count; |
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65 #endif |
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66 |
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67 // At a safepoint, visit all threads and count the number of active |
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68 // critical sections. This is used to ensure that all active |
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69 // critical sections are exited before a new one is started. |
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70 static void verify_critical_count() NOT_DEBUG_RETURN; |
0 | 71 |
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72 static void jni_lock(JavaThread* thread); |
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73 static void jni_unlock(JavaThread* thread); |
0 | 74 |
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75 static bool is_active_internal() { |
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76 verify_critical_count(); |
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77 return _jni_lock_count > 0; |
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78 } |
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79 |
0 | 80 public: |
81 // Accessors | |
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82 static bool is_active() { |
12301 | 83 assert(SafepointSynchronize::is_at_safepoint(), "only read at safepoint"); |
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84 return is_active_internal(); |
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85 } |
0 | 86 static bool needs_gc() { return _needs_gc; } |
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87 |
0 | 88 // Shorthand |
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89 static bool is_active_and_needs_gc() { |
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90 // Use is_active_internal since _needs_gc can change from true to |
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91 // false outside of a safepoint, triggering the assert in |
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92 // is_active. |
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93 return needs_gc() && is_active_internal(); |
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94 } |
0 | 95 |
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96 // In debug mode track the locking state at all times |
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97 static void increment_debug_jni_lock_count() { |
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98 #ifdef ASSERT |
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99 assert(_debug_jni_lock_count >= 0, "bad value"); |
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100 Atomic::inc(&_debug_jni_lock_count); |
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101 #endif |
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102 } |
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103 static void decrement_debug_jni_lock_count() { |
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104 #ifdef ASSERT |
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105 assert(_debug_jni_lock_count > 0, "bad value"); |
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106 Atomic::dec(&_debug_jni_lock_count); |
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107 #endif |
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108 } |
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109 |
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110 // Set the current lock count |
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111 static void set_jni_lock_count(int count) { |
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112 _jni_lock_count = count; |
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113 verify_critical_count(); |
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114 } |
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115 |
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116 // Sets _needs_gc if is_active() is true. Returns is_active(). |
0 | 117 static bool check_active_before_gc(); |
118 | |
119 // Stalls the caller (who should not be in a jni critical section) | |
120 // until needs_gc() clears. Note however that needs_gc() may be | |
121 // set at a subsequent safepoint and/or cleared under the | |
122 // JNICritical_lock, so the caller may not safely assert upon | |
123 // return from this method that "!needs_gc()" since that is | |
124 // not a stable predicate. | |
125 static void stall_until_clear(); | |
126 | |
127 // The following two methods are used for JNI critical regions. | |
128 // If we find that we failed to perform a GC because the GC_locker | |
129 // was active, arrange for one as soon as possible by allowing | |
130 // all threads in critical regions to complete, but not allowing | |
131 // other critical regions to be entered. The reasons for that are: | |
132 // 1) a GC request won't be starved by overlapping JNI critical | |
133 // region activities, which can cause unnecessary OutOfMemory errors. | |
134 // 2) even if allocation requests can still be satisfied before GC locker | |
135 // becomes inactive, for example, in tenured generation possibly with | |
136 // heap expansion, those allocations can trigger lots of safepointing | |
137 // attempts (ineffective GC attempts) and require Heap_lock which | |
138 // slow down allocations tremendously. | |
139 // | |
140 // Note that critical regions can be nested in a single thread, so | |
141 // we must allow threads already in critical regions to continue. | |
142 // | |
143 // JNI critical regions are the only participants in this scheme | |
144 // because they are, by spec, well bounded while in a critical region. | |
145 // | |
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146 // Each of the following two method is split into a fast path and a |
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147 // slow path. JNICritical_lock is only grabbed in the slow path. |
0 | 148 // _needs_gc is initially false and every java thread will go |
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149 // through the fast path, which simply increments or decrements the |
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150 // current thread's critical count. When GC happens at a safepoint, |
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151 // GC_locker::is_active() is checked. Since there is no safepoint in |
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152 // the fast path of lock_critical() and unlock_critical(), there is |
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153 // no race condition between the fast path and GC. After _needs_gc |
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154 // is set at a safepoint, every thread will go through the slow path |
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155 // after the safepoint. Since after a safepoint, each of the |
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156 // following two methods is either entered from the method entry and |
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157 // falls into the slow path, or is resumed from the safepoints in |
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158 // the method, which only exist in the slow path. So when _needs_gc |
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159 // is set, the slow path is always taken, till _needs_gc is cleared. |
0 | 160 static void lock_critical(JavaThread* thread); |
161 static void unlock_critical(JavaThread* thread); | |
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162 |
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163 static address needs_gc_address() { return (address) &_needs_gc; } |
0 | 164 }; |
165 | |
166 | |
167 // A No_GC_Verifier object can be placed in methods where one assumes that | |
168 // no garbage collection will occur. The destructor will verify this property | |
169 // unless the constructor is called with argument false (not verifygc). | |
170 // | |
171 // The check will only be done in debug mode and if verifygc true. | |
172 | |
173 class No_GC_Verifier: public StackObj { | |
174 friend class Pause_No_GC_Verifier; | |
175 | |
176 protected: | |
177 bool _verifygc; | |
178 unsigned int _old_invocations; | |
179 | |
180 public: | |
181 #ifdef ASSERT | |
182 No_GC_Verifier(bool verifygc = true); | |
183 ~No_GC_Verifier(); | |
184 #else | |
185 No_GC_Verifier(bool verifygc = true) {} | |
186 ~No_GC_Verifier() {} | |
187 #endif | |
188 }; | |
189 | |
190 // A Pause_No_GC_Verifier is used to temporarily pause the behavior | |
191 // of a No_GC_Verifier object. If we are not in debug mode or if the | |
192 // No_GC_Verifier object has a _verifygc value of false, then there | |
193 // is nothing to do. | |
194 | |
195 class Pause_No_GC_Verifier: public StackObj { | |
196 private: | |
197 No_GC_Verifier * _ngcv; | |
198 | |
199 public: | |
200 #ifdef ASSERT | |
201 Pause_No_GC_Verifier(No_GC_Verifier * ngcv); | |
202 ~Pause_No_GC_Verifier(); | |
203 #else | |
204 Pause_No_GC_Verifier(No_GC_Verifier * ngcv) {} | |
205 ~Pause_No_GC_Verifier() {} | |
206 #endif | |
207 }; | |
208 | |
209 | |
210 // A No_Safepoint_Verifier object will throw an assertion failure if | |
211 // the current thread passes a possible safepoint while this object is | |
212 // instantiated. A safepoint, will either be: an oop allocation, blocking | |
213 // on a Mutex or JavaLock, or executing a VM operation. | |
214 // | |
215 // If StrictSafepointChecks is turned off, it degrades into a No_GC_Verifier | |
216 // | |
217 class No_Safepoint_Verifier : public No_GC_Verifier { | |
218 friend class Pause_No_Safepoint_Verifier; | |
219 | |
220 private: | |
221 bool _activated; | |
222 Thread *_thread; | |
223 public: | |
224 #ifdef ASSERT | |
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225 No_Safepoint_Verifier(bool activated = true, bool verifygc = true ) : |
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226 No_GC_Verifier(verifygc), |
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227 _activated(activated) { |
0 | 228 _thread = Thread::current(); |
229 if (_activated) { | |
230 _thread->_allow_allocation_count++; | |
231 _thread->_allow_safepoint_count++; | |
232 } | |
233 } | |
234 | |
235 ~No_Safepoint_Verifier() { | |
236 if (_activated) { | |
237 _thread->_allow_allocation_count--; | |
238 _thread->_allow_safepoint_count--; | |
239 } | |
240 } | |
241 #else | |
242 No_Safepoint_Verifier(bool activated = true, bool verifygc = true) : No_GC_Verifier(verifygc){} | |
243 ~No_Safepoint_Verifier() {} | |
244 #endif | |
245 }; | |
246 | |
247 // A Pause_No_Safepoint_Verifier is used to temporarily pause the | |
248 // behavior of a No_Safepoint_Verifier object. If we are not in debug | |
249 // mode then there is nothing to do. If the No_Safepoint_Verifier | |
250 // object has an _activated value of false, then there is nothing to | |
251 // do for safepoint and allocation checking, but there may still be | |
252 // something to do for the underlying No_GC_Verifier object. | |
253 | |
254 class Pause_No_Safepoint_Verifier : public Pause_No_GC_Verifier { | |
255 private: | |
256 No_Safepoint_Verifier * _nsv; | |
257 | |
258 public: | |
259 #ifdef ASSERT | |
260 Pause_No_Safepoint_Verifier(No_Safepoint_Verifier * nsv) | |
261 : Pause_No_GC_Verifier(nsv) { | |
262 | |
263 _nsv = nsv; | |
264 if (_nsv->_activated) { | |
265 _nsv->_thread->_allow_allocation_count--; | |
266 _nsv->_thread->_allow_safepoint_count--; | |
267 } | |
268 } | |
269 | |
270 ~Pause_No_Safepoint_Verifier() { | |
271 if (_nsv->_activated) { | |
272 _nsv->_thread->_allow_allocation_count++; | |
273 _nsv->_thread->_allow_safepoint_count++; | |
274 } | |
275 } | |
276 #else | |
277 Pause_No_Safepoint_Verifier(No_Safepoint_Verifier * nsv) | |
278 : Pause_No_GC_Verifier(nsv) {} | |
279 ~Pause_No_Safepoint_Verifier() {} | |
280 #endif | |
281 }; | |
282 | |
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283 // A SkipGCALot object is used to elide the usual effect of gc-a-lot |
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284 // over a section of execution by a thread. Currently, it's used only to |
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285 // prevent re-entrant calls to GC. |
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286 class SkipGCALot : public StackObj { |
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287 private: |
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288 bool _saved; |
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289 Thread* _t; |
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290 |
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291 public: |
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292 #ifdef ASSERT |
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293 SkipGCALot(Thread* t) : _t(t) { |
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294 _saved = _t->skip_gcalot(); |
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295 _t->set_skip_gcalot(true); |
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296 } |
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297 |
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298 ~SkipGCALot() { |
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299 assert(_t->skip_gcalot(), "Save-restore protocol invariant"); |
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300 _t->set_skip_gcalot(_saved); |
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301 } |
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302 #else |
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303 SkipGCALot(Thread* t) { } |
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304 ~SkipGCALot() { } |
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305 #endif |
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306 }; |
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307 |
0 | 308 // JRT_LEAF currently can be called from either _thread_in_Java or |
309 // _thread_in_native mode. In _thread_in_native, it is ok | |
310 // for another thread to trigger GC. The rest of the JRT_LEAF | |
311 // rules apply. | |
312 class JRT_Leaf_Verifier : public No_Safepoint_Verifier { | |
313 static bool should_verify_GC(); | |
314 public: | |
315 #ifdef ASSERT | |
316 JRT_Leaf_Verifier(); | |
317 ~JRT_Leaf_Verifier(); | |
318 #else | |
319 JRT_Leaf_Verifier() {} | |
320 ~JRT_Leaf_Verifier() {} | |
321 #endif | |
322 }; | |
323 | |
324 // A No_Alloc_Verifier object can be placed in methods where one assumes that | |
325 // no allocation will occur. The destructor will verify this property | |
326 // unless the constructor is called with argument false (not activated). | |
327 // | |
328 // The check will only be done in debug mode and if activated. | |
329 // Note: this only makes sense at safepoints (otherwise, other threads may | |
330 // allocate concurrently.) | |
331 | |
332 class No_Alloc_Verifier : public StackObj { | |
333 private: | |
334 bool _activated; | |
335 | |
336 public: | |
337 #ifdef ASSERT | |
338 No_Alloc_Verifier(bool activated = true) { | |
339 _activated = activated; | |
340 if (_activated) Thread::current()->_allow_allocation_count++; | |
341 } | |
342 | |
343 ~No_Alloc_Verifier() { | |
344 if (_activated) Thread::current()->_allow_allocation_count--; | |
345 } | |
346 #else | |
347 No_Alloc_Verifier(bool activated = true) {} | |
348 ~No_Alloc_Verifier() {} | |
349 #endif | |
350 }; | |
1972 | 351 |
352 #endif // SHARE_VM_MEMORY_GCLOCKER_HPP |