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 }