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/*
* Copyright (c) 2016, 2023, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
#include "precompiled.hpp"
#include "classfile/symbolTable.hpp"
#include "runtime/interfaceSupport.inline.hpp"
#include "threadHelper.inline.hpp"
#include "unittest.hpp"
// Helper to avoid interference from the cleanup delay queue by draining it
// immediately after creation.
TempNewSymbol stable_temp_symbol(Symbol* sym) {
TempNewSymbol t = sym;
TempSymbolCleanupDelayer::drain_queue();
return t;
}
TEST_VM(SymbolTable, temp_new_symbol) {
// Assert messages assume these symbols are unique, and the refcounts start at
// one, but code does not rely on this.
JavaThread* THREAD = JavaThread::current();
// the thread should be in vm to use locks
ThreadInVMfromNative ThreadInVMfromNative(THREAD);
Symbol* abc = SymbolTable::new_symbol("abc");
int abccount = abc->refcount();
TempNewSymbol ss = stable_temp_symbol(abc);
ASSERT_EQ(ss->refcount(), abccount) << "only one abc";
ASSERT_EQ(ss->refcount(), abc->refcount()) << "should match TempNewSymbol";
Symbol* efg = SymbolTable::new_symbol("efg");
Symbol* hij = SymbolTable::new_symbol("hij");
int efgcount = efg->refcount();
int hijcount = hij->refcount();
TempNewSymbol s1 = stable_temp_symbol(efg);
TempNewSymbol s2 = stable_temp_symbol(hij);
ASSERT_EQ(s1->refcount(), efgcount) << "one efg";
ASSERT_EQ(s2->refcount(), hijcount) << "one hij";
// Assignment operator
s1 = s2;
ASSERT_EQ(hij->refcount(), hijcount + 1) << "should be two hij";
ASSERT_EQ(efg->refcount(), efgcount - 1) << "should be no efg";
s1 = ss; // s1 is abc
ASSERT_EQ(s1->refcount(), abccount + 1) << "should be two abc (s1 and ss)";
ASSERT_EQ(hij->refcount(), hijcount) << "should only have one hij now (s2)";
s1 = *&s1; // self assignment
ASSERT_EQ(s1->refcount(), abccount + 1) << "should still be two abc (s1 and ss)";
TempNewSymbol s3;
Symbol* klm = SymbolTable::new_symbol("klm");
int klmcount = klm->refcount();
s3 = stable_temp_symbol(klm); // assignment
ASSERT_EQ(s3->refcount(), klmcount) << "only one klm now";
Symbol* xyz = SymbolTable::new_symbol("xyz");
int xyzcount = xyz->refcount();
{ // inner scope
TempNewSymbol s_inner = stable_temp_symbol(xyz);
}
ASSERT_EQ(xyz->refcount(), xyzcount - 1)
<< "Should have been decremented by dtor in inner scope";
// Test overflowing refcount making symbol permanent
Symbol* bigsym = SymbolTable::new_symbol("bigsym");
for (int i = 0; i < PERM_REFCOUNT + 100; i++) {
bigsym->increment_refcount();
}
ASSERT_EQ(bigsym->refcount(), PERM_REFCOUNT) << "should not have overflowed";
// Test that PERM_REFCOUNT is sticky
for (int i = 0; i < 10; i++) {
bigsym->decrement_refcount();
}
ASSERT_EQ(bigsym->refcount(), PERM_REFCOUNT) << "should be sticky";
}
// TODO: Make two threads one decrementing the refcount and the other trying to increment.
// try_increment_refcount should return false
TEST_VM(SymbolTable, test_symbol_refcount_parallel) {
constexpr int symbol_name_length = 30;
char symbol_name[symbol_name_length];
// Find a symbol where there will probably be only one instance.
for (int i = 0; i < 100; i++) {
os::snprintf(symbol_name, symbol_name_length, "some_symbol%d", i);
TempNewSymbol ts = SymbolTable::new_symbol(symbol_name);
if (ts->refcount() == 1) {
EXPECT_TRUE(ts->refcount() == 1) << "Symbol is just created";
break; // found a unique symbol
}
}
constexpr int symTestThreadCount = 5;
auto symbolThread= [&](Thread* _current, int _id) {
for (int i = 0; i < 1000; i++) {
TempNewSymbol sym = SymbolTable::new_symbol(symbol_name);
// Create and destroy new symbol
EXPECT_TRUE(sym->refcount() != 0) << "Symbol refcount unexpectedly zeroed";
}
};
TestThreadGroup<decltype(symbolThread)> ttg(symbolThread, symTestThreadCount);
ttg.doit();
ttg.join();
}
TEST_VM_FATAL_ERROR_MSG(SymbolTable, test_symbol_underflow, ".*refcount has gone to zero.*") {
Symbol* my_symbol = SymbolTable::new_symbol("my_symbol2023");
EXPECT_TRUE(my_symbol->refcount() == 1) << "Symbol refcount just created is 1";
my_symbol->decrement_refcount();
my_symbol->increment_refcount(); // Should crash even in PRODUCT mode
}
TEST_VM(SymbolTable, test_cleanup_leak) {
// Check that dead entry cleanup doesn't increment refcount of live entry in same bucket.
// Create symbol and release ref, marking it available for cleanup.
Symbol* entry1 = SymbolTable::new_symbol("hash_collision_123");
entry1->decrement_refcount();
// Create a new symbol in the same bucket, which will notice the dead entry and trigger cleanup.
// Note: relies on SymbolTable's use of String::hashCode which collides for these two values.
Symbol* entry2 = SymbolTable::new_symbol("hash_collision_397476851");
ASSERT_EQ(entry2->refcount(), 1) << "Symbol refcount just created is 1";
}
TEST_VM(SymbolTable, test_cleanup_delay) {
// Check that new temp symbols have an extra refcount increment, which is then
// decremented when the queue spills over.
TempNewSymbol s1 = SymbolTable::new_symbol("temp-s1");
ASSERT_EQ(s1->refcount(), 2) << "TempNewSymbol refcount just created is 2";
// Fill up the queue
constexpr int symbol_name_length = 30;
char symbol_name[symbol_name_length];
for (uint i = 1; i < TempSymbolCleanupDelayer::QueueSize; i++) {
os::snprintf(symbol_name, symbol_name_length, "temp-filler-%d", i);
TempNewSymbol s = SymbolTable::new_symbol(symbol_name);
ASSERT_EQ(s->refcount(), 2) << "TempNewSymbol refcount just created is 2";
}
// Add one more
TempNewSymbol spillover = SymbolTable::new_symbol("temp-spillover");
ASSERT_EQ(spillover->refcount(), 2) << "TempNewSymbol refcount just created is 2";
// The first symbol should have been removed from the queue and decremented
ASSERT_EQ(s1->refcount(), 1) << "TempNewSymbol off queue refcount is 1";
}
TEST_VM(SymbolTable, test_cleanup_delay_drain) {
// Fill up the queue
constexpr int symbol_name_length = 30;
char symbol_name[symbol_name_length];
TempNewSymbol symbols[TempSymbolCleanupDelayer::QueueSize] = {};
for (uint i = 0; i < TempSymbolCleanupDelayer::QueueSize; i++) {
os::snprintf(symbol_name, symbol_name_length, "temp-%d", i);
TempNewSymbol s = SymbolTable::new_symbol(symbol_name);
symbols[i] = s;
}
// While in the queue refcounts are incremented
for (uint i = 0; i < TempSymbolCleanupDelayer::QueueSize; i++) {
ASSERT_EQ(symbols[i]->refcount(), 2) << "TempNewSymbol refcount in queue is 2";
}
// Draining the queue should decrement the refcounts
TempSymbolCleanupDelayer::drain_queue();
for (uint i = 0; i < TempSymbolCleanupDelayer::QueueSize; i++) {
ASSERT_EQ(symbols[i]->refcount(), 1) << "TempNewSymbol refcount after drain is 1";
}
}
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