1 /*
  2  * Copyright (c) 2016, 2019, 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 "runtime/interfaceSupport.inline.hpp"
 26 #include "classfile/symbolTable.hpp"
 27 #include "threadHelper.inline.hpp"
 28 #include "unittest.hpp"
 29 
 30 TEST_VM(SymbolTable, temp_new_symbol) {
 31   // Assert messages assume these symbols are unique, and the refcounts start at
 32   // one, but code does not rely on this.
 33   JavaThread* THREAD = JavaThread::current();
 34   // the thread should be in vm to use locks
 35   ThreadInVMfromNative ThreadInVMfromNative(THREAD);
 36 
 37   Symbol* abc = SymbolTable::new_symbol("abc");
 38   int abccount = abc->refcount();
 39   TempNewSymbol ss = abc;
 40   ASSERT_EQ(ss->refcount(), abccount) << "only one abc";
 41   ASSERT_EQ(ss->refcount(), abc->refcount()) << "should match TempNewSymbol";
 42 
 43   Symbol* efg = SymbolTable::new_symbol("efg");
 44   Symbol* hij = SymbolTable::new_symbol("hij");
 45   int efgcount = efg->refcount();
 46   int hijcount = hij->refcount();
 47 
 48   TempNewSymbol s1 = efg;
 49   TempNewSymbol s2 = hij;
 50   ASSERT_EQ(s1->refcount(), efgcount) << "one efg";
 51   ASSERT_EQ(s2->refcount(), hijcount) << "one hij";
 52 
 53   // Assignment operator
 54   s1 = s2;
 55   ASSERT_EQ(hij->refcount(), hijcount + 1) << "should be two hij";
 56   ASSERT_EQ(efg->refcount(), efgcount - 1) << "should be no efg";
 57 
 58   s1 = ss; // s1 is abc
 59   ASSERT_EQ(s1->refcount(), abccount + 1) << "should be two abc (s1 and ss)";
 60   ASSERT_EQ(hij->refcount(), hijcount) << "should only have one hij now (s2)";
 61 
 62   s1 = *&s1; // self assignment
 63   ASSERT_EQ(s1->refcount(), abccount + 1) << "should still be two abc (s1 and ss)";
 64 
 65   TempNewSymbol s3;
 66   Symbol* klm = SymbolTable::new_symbol("klm");
 67   int klmcount = klm->refcount();
 68   s3 = klm; // assignment
 69   ASSERT_EQ(s3->refcount(), klmcount) << "only one klm now";
 70 
 71   Symbol* xyz = SymbolTable::new_symbol("xyz");
 72   int xyzcount = xyz->refcount();
 73   { // inner scope
 74     TempNewSymbol s_inner = xyz;
 75   }
 76   ASSERT_EQ(xyz->refcount(), xyzcount - 1)
 77           << "Should have been decremented by dtor in inner scope";
 78 
 79   // Test overflowing refcount making symbol permanent
 80   Symbol* bigsym = SymbolTable::new_symbol("bigsym");
 81   for (int i = 0; i < PERM_REFCOUNT + 100; i++) {
 82     bigsym->increment_refcount();
 83   }
 84   ASSERT_EQ(bigsym->refcount(), PERM_REFCOUNT) << "should not have overflowed";
 85 
 86   // Test that PERM_REFCOUNT is sticky
 87   for (int i = 0; i < 10; i++) {
 88     bigsym->decrement_refcount();
 89   }
 90   ASSERT_EQ(bigsym->refcount(), PERM_REFCOUNT) << "should be sticky";
 91 }
 92 
 93 // TODO: Make two threads one decrementing the refcount and the other trying to increment.
 94 // try_increment_refcount should return false
 95 
 96 #define SYM_NAME_LENGTH 30
 97 static char symbol_name[SYM_NAME_LENGTH];
 98 
 99 class SymbolThread : public JavaTestThread {
100   public:
101   SymbolThread(Semaphore* post) : JavaTestThread(post) {}
102   virtual ~SymbolThread() {}
103   void main_run() {
104     for (int i = 0; i < 1000; i++) {
105       TempNewSymbol sym = SymbolTable::new_symbol(symbol_name);
106       // Create and destroy new symbol
107       EXPECT_TRUE(sym->refcount() != 0) << "Symbol refcount unexpectedly zeroed";
108     }
109   }
110 };
111 
112 #define SYM_TEST_THREAD_COUNT 5
113 
114 class DriverSymbolThread : public JavaTestThread {
115 public:
116   Semaphore _done;
117   DriverSymbolThread(Semaphore* post) : JavaTestThread(post) { };
118   virtual ~DriverSymbolThread(){}
119 
120   void main_run() {
121     Semaphore done(0);
122 
123     // Find a symbol where there will probably be only one instance.
124     for (int i = 0; i < 100; i++) {
125        os::snprintf(symbol_name, SYM_NAME_LENGTH, "some_symbol%d", i);
126        TempNewSymbol ts = SymbolTable::new_symbol(symbol_name);
127        if (ts->refcount() == 1) {
128          EXPECT_TRUE(ts->refcount() == 1) << "Symbol is just created";
129          break;  // found a unique symbol
130        }
131     }
132 
133     SymbolThread* st[SYM_TEST_THREAD_COUNT];
134     for (int i = 0; i < SYM_TEST_THREAD_COUNT; i++) {
135       st[i] = new SymbolThread(&done);
136       st[i]->doit();
137     }
138 
139     for (int i = 0; i < SYM_TEST_THREAD_COUNT; i++) {
140       done.wait();
141     }
142   }
143 };
144 
145 TEST_VM(SymbolTable, test_symbol_refcount_parallel) {
146   mt_test_doer<DriverSymbolThread>();
147 }