1 /*
   2  * Copyright (c) 2019, 2020, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  */
  23 
  24 #include "precompiled.hpp"
  25 #include "classfile/systemDictionary.hpp"
  26 #include "memory/resourceArea.hpp"
  27 #include "memory/universe.hpp"
  28 #include "oops/oop.inline.hpp"
  29 #include "runtime/atomic.hpp"
  30 #include "runtime/biasedLocking.hpp"
  31 #include "runtime/interfaceSupport.inline.hpp"
  32 #include "runtime/orderAccess.hpp"
  33 #include "runtime/os.hpp"
  34 #include "runtime/synchronizer.hpp"
  35 #include "runtime/semaphore.inline.hpp"
  36 #include "threadHelper.inline.hpp"
  37 #include "unittest.hpp"
  38 #include "utilities/globalDefinitions.hpp"
  39 #include "utilities/ostream.hpp"
  40 
  41 // The test doesn't work for PRODUCT because it needs WizardMode
  42 #ifndef PRODUCT
  43 static bool test_pattern(stringStream* st, const char* pattern) {
  44   return (strstr(st->as_string(), pattern) != NULL);
  45 }
  46 
  47 static void assert_test_pattern(Handle object, const char* pattern) {
  48   stringStream st;
  49   object->print_on(&st);
  50   ASSERT_TRUE(test_pattern(&st, pattern)) << pattern << " not in " << st.as_string();
  51 }
  52 
  53 static void assert_not_test_pattern(Handle object, const char* pattern) {
  54   stringStream st;
  55   object->print_on(&st);
  56   ASSERT_FALSE(test_pattern(&st, pattern)) << pattern << " found in " << st.as_string();
  57 }
  58 
  59 class LockerThread : public JavaTestThread {
  60   oop _obj;
  61   public:
  62   LockerThread(Semaphore* post, oop obj) : JavaTestThread(post), _obj(obj) {}
  63   virtual ~LockerThread() {}
  64 
  65   void main_run() {
  66     Thread* THREAD = Thread::current();
  67     HandleMark hm(THREAD);
  68     Handle h_obj(THREAD, _obj);
  69     ResourceMark rm(THREAD);
  70 
  71     // Wait gets the lock inflated.
  72     // The object will stay locked for the context of 'ol' so the lock will
  73     // still be inflated after the notify_all() call. Deflation can't happen
  74     // while an ObjectMonitor is "busy" and being locked is the most "busy"
  75     // state we have...
  76     ObjectLocker ol(h_obj, THREAD);
  77     ol.notify_all(THREAD);
  78     assert_test_pattern(h_obj, "monitor");
  79   }
  80 };
  81 
  82 
  83 TEST_VM(markWord, printing) {
  84   JavaThread* THREAD = JavaThread::current();
  85   ThreadInVMfromNative invm(THREAD);
  86   ResourceMark rm(THREAD);
  87 
  88   if (!UseBiasedLocking || !BiasedLocking::enabled()) {
  89     // Can't test this with biased locking disabled.
  90     return;
  91   }
  92 
  93   oop obj = SystemDictionary::Byte_klass()->allocate_instance(THREAD);
  94 
  95   FlagSetting fs(WizardMode, true);
  96 
  97   HandleMark hm(THREAD);
  98   Handle h_obj(THREAD, obj);
  99 
 100   // Biased locking is initially enabled for this java.lang.Byte object.
 101   assert_test_pattern(h_obj, "is_biased");
 102 
 103   // Lock using biased locking.
 104   BasicObjectLock lock;
 105   lock.set_obj(obj);
 106   markWord prototype_header = obj->klass()->prototype_header();
 107   markWord mark = obj->mark();
 108   markWord biased_mark = markWord::encode((JavaThread*) THREAD, mark.age(), prototype_header.bias_epoch());
 109   obj->set_mark(biased_mark);
 110   // Look for the biased_locker in markWord, not prototype_header.
 111 #ifdef _LP64
 112   assert_not_test_pattern(h_obj, "mark(is_biased biased_locker=0x0000000000000000");
 113 #else
 114   assert_not_test_pattern(h_obj, "mark(is_biased biased_locker=0x00000000");
 115 #endif
 116 
 117   // Same thread tries to lock it again.
 118   {
 119     ObjectLocker ol(h_obj, THREAD);
 120     assert_test_pattern(h_obj, "locked");
 121   }
 122 
 123   // This is no longer biased, because ObjectLocker revokes the bias.
 124   assert_test_pattern(h_obj, "is_neutral no_hash");
 125 
 126   // Hash the object then print it.
 127   intx hash = h_obj->identity_hash();
 128   assert_test_pattern(h_obj, "is_neutral hash=0x");
 129 
 130   // Wait gets the lock inflated.
 131   {
 132     ObjectLocker ol(h_obj, THREAD);
 133 
 134     Semaphore done(0);
 135     LockerThread* st;
 136     st = new LockerThread(&done, h_obj());
 137     st->doit();
 138 
 139     ol.wait(THREAD);
 140     assert_test_pattern(h_obj, "monitor");
 141     done.wait_with_safepoint_check(THREAD);  // wait till the thread is done.
 142   }
 143 
 144   if (!AsyncDeflateIdleMonitors) {
 145     // With AsyncDeflateIdleMonitors, the collect() call below
 146     // does not guarantee monitor deflation.
 147     // Make the object older. Not all GCs use this field.
 148     Universe::heap()->collect(GCCause::_java_lang_system_gc);
 149     if (UseParallelGC) {
 150       assert_test_pattern(h_obj, "is_neutral no_hash age 1");
 151     }
 152 
 153     // Hash the object then print it.
 154     intx hash = h_obj->identity_hash();
 155     assert_test_pattern(h_obj, "is_neutral hash=0x");
 156   }
 157 }
 158 #endif // PRODUCT