Mercurial > hg > graal-compiler
view src/share/vm/classfile/symbolTable.cpp @ 616:4f360ec815ba
6720309: G1: don't synchronously update RSet during evacuation pauses
6720334: G1: don't update RSets of collection set regions during an evacuation pause
Summary: Introduced a deferred update mechanism for delaying the rset updates during the collection pause
Reviewed-by: apetrusenko, tonyp
author | iveresov |
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date | Fri, 06 Mar 2009 13:50:14 -0800 |
parents | a61af66fc99e |
children | 98cb887364d3 |
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/* * Copyright 1997-2006 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, * CA 95054 USA or visit www.sun.com if you need additional information or * have any questions. * */ # include "incls/_precompiled.incl" # include "incls/_symbolTable.cpp.incl" // -------------------------------------------------------------------------- SymbolTable* SymbolTable::_the_table = NULL; // Lookup a symbol in a bucket. symbolOop SymbolTable::lookup(int index, const char* name, int len, unsigned int hash) { for (HashtableEntry* e = bucket(index); e != NULL; e = e->next()) { if (e->hash() == hash) { symbolOop sym = symbolOop(e->literal()); if (sym->equals(name, len)) { return sym; } } } return NULL; } // We take care not to be blocking while holding the // SymbolTable_lock. Otherwise, the system might deadlock, since the // symboltable is used during compilation (VM_thread) The lock free // synchronization is simplified by the fact that we do not delete // entries in the symbol table during normal execution (only during // safepoints). symbolOop SymbolTable::lookup(const char* name, int len, TRAPS) { unsigned int hashValue = hash_symbol(name, len); int index = the_table()->hash_to_index(hashValue); symbolOop s = the_table()->lookup(index, name, len, hashValue); // Found if (s != NULL) return s; // Otherwise, add to symbol to table return the_table()->basic_add(index, (u1*)name, len, hashValue, CHECK_NULL); } symbolOop SymbolTable::lookup(symbolHandle sym, int begin, int end, TRAPS) { char* buffer; int index, len; unsigned int hashValue; char* name; { debug_only(No_Safepoint_Verifier nsv;) name = (char*)sym->base() + begin; len = end - begin; hashValue = hash_symbol(name, len); index = the_table()->hash_to_index(hashValue); symbolOop s = the_table()->lookup(index, name, len, hashValue); // Found if (s != NULL) return s; } // Otherwise, add to symbol to table. Copy to a C string first. char stack_buf[128]; ResourceMark rm(THREAD); if (len <= 128) { buffer = stack_buf; } else { buffer = NEW_RESOURCE_ARRAY_IN_THREAD(THREAD, char, len); } for (int i=0; i<len; i++) { buffer[i] = name[i]; } // Make sure there is no safepoint in the code above since name can't move. // We can't include the code in No_Safepoint_Verifier because of the // ResourceMark. return the_table()->basic_add(index, (u1*)buffer, len, hashValue, CHECK_NULL); } symbolOop SymbolTable::lookup_only(const char* name, int len, unsigned int& hash) { hash = hash_symbol(name, len); int index = the_table()->hash_to_index(hash); return the_table()->lookup(index, name, len, hash); } void SymbolTable::add(constantPoolHandle cp, int names_count, const char** names, int* lengths, int* cp_indices, unsigned int* hashValues, TRAPS) { SymbolTable* table = the_table(); bool added = table->basic_add(cp, names_count, names, lengths, cp_indices, hashValues, CHECK); if (!added) { // do it the hard way for (int i=0; i<names_count; i++) { int index = table->hash_to_index(hashValues[i]); symbolOop sym = table->basic_add(index, (u1*)names[i], lengths[i], hashValues[i], CHECK); cp->symbol_at_put(cp_indices[i], sym); } } } // Needed for preloading classes in signatures when compiling. symbolOop SymbolTable::probe(const char* name, int len) { unsigned int hashValue = hash_symbol(name, len); int index = the_table()->hash_to_index(hashValue); return the_table()->lookup(index, name, len, hashValue); } symbolOop SymbolTable::basic_add(int index, u1 *name, int len, unsigned int hashValue, TRAPS) { assert(!Universe::heap()->is_in_reserved(name) || GC_locker::is_active(), "proposed name of symbol must be stable"); // We assume that lookup() has been called already, that it failed, // and symbol was not found. We create the symbol here. symbolKlass* sk = (symbolKlass*) Universe::symbolKlassObj()->klass_part(); symbolOop s_oop = sk->allocate_symbol(name, len, CHECK_NULL); symbolHandle sym (THREAD, s_oop); // Allocation must be done before grapping the SymbolTable_lock lock MutexLocker ml(SymbolTable_lock, THREAD); assert(sym->equals((char*)name, len), "symbol must be properly initialized"); // Since look-up was done lock-free, we need to check if another // thread beat us in the race to insert the symbol. symbolOop test = lookup(index, (char*)name, len, hashValue); if (test != NULL) { // A race occured and another thread introduced the symbol, this one // will be dropped and collected. return test; } HashtableEntry* entry = new_entry(hashValue, sym()); add_entry(index, entry); return sym(); } bool SymbolTable::basic_add(constantPoolHandle cp, int names_count, const char** names, int* lengths, int* cp_indices, unsigned int* hashValues, TRAPS) { symbolKlass* sk = (symbolKlass*) Universe::symbolKlassObj()->klass_part(); symbolOop sym_oops[symbol_alloc_batch_size]; bool allocated = sk->allocate_symbols(names_count, names, lengths, sym_oops, CHECK_false); if (!allocated) { return false; } symbolHandle syms[symbol_alloc_batch_size]; int i; for (i=0; i<names_count; i++) { syms[i] = symbolHandle(THREAD, sym_oops[i]); } // Allocation must be done before grabbing the SymbolTable_lock lock MutexLocker ml(SymbolTable_lock, THREAD); for (i=0; i<names_count; i++) { assert(syms[i]->equals(names[i], lengths[i]), "symbol must be properly initialized"); // Since look-up was done lock-free, we need to check if another // thread beat us in the race to insert the symbol. int index = hash_to_index(hashValues[i]); symbolOop test = lookup(index, names[i], lengths[i], hashValues[i]); if (test != NULL) { // A race occured and another thread introduced the symbol, this one // will be dropped and collected. Use test instead. cp->symbol_at_put(cp_indices[i], test); } else { symbolOop sym = syms[i](); HashtableEntry* entry = new_entry(hashValues[i], sym); add_entry(index, entry); cp->symbol_at_put(cp_indices[i], sym); } } return true; } void SymbolTable::verify() { for (int i = 0; i < the_table()->table_size(); ++i) { HashtableEntry* p = the_table()->bucket(i); for ( ; p != NULL; p = p->next()) { symbolOop s = symbolOop(p->literal()); guarantee(s != NULL, "symbol is NULL"); s->verify(); guarantee(s->is_perm(), "symbol not in permspace"); unsigned int h = hash_symbol((char*)s->bytes(), s->utf8_length()); guarantee(p->hash() == h, "broken hash in symbol table entry"); guarantee(the_table()->hash_to_index(h) == i, "wrong index in symbol table"); } } } //--------------------------------------------------------------------------- // Non-product code #ifndef PRODUCT void SymbolTable::print_histogram() { MutexLocker ml(SymbolTable_lock); const int results_length = 100; int results[results_length]; int i,j; // initialize results to zero for (j = 0; j < results_length; j++) { results[j] = 0; } int total = 0; int max_symbols = 0; int out_of_range = 0; for (i = 0; i < the_table()->table_size(); i++) { HashtableEntry* p = the_table()->bucket(i); for ( ; p != NULL; p = p->next()) { int counter = symbolOop(p->literal())->utf8_length(); total += counter; if (counter < results_length) { results[counter]++; } else { out_of_range++; } max_symbols = MAX2(max_symbols, counter); } } tty->print_cr("Symbol Table:"); tty->print_cr("%8s %5d", "Total ", total); tty->print_cr("%8s %5d", "Maximum", max_symbols); tty->print_cr("%8s %3.2f", "Average", ((float) total / (float) the_table()->table_size())); tty->print_cr("%s", "Histogram:"); tty->print_cr(" %s %29s", "Length", "Number chains that length"); for (i = 0; i < results_length; i++) { if (results[i] > 0) { tty->print_cr("%6d %10d", i, results[i]); } } int line_length = 70; tty->print_cr("%s %30s", " Length", "Number chains that length"); for (i = 0; i < results_length; i++) { if (results[i] > 0) { tty->print("%4d", i); for (j = 0; (j < results[i]) && (j < line_length); j++) { tty->print("%1s", "*"); } if (j == line_length) { tty->print("%1s", "+"); } tty->cr(); } } tty->print_cr(" %s %d: %d\n", "Number chains longer than", results_length, out_of_range); } #endif // PRODUCT // -------------------------------------------------------------------------- #ifdef ASSERT class StableMemoryChecker : public StackObj { enum { _bufsize = wordSize*4 }; address _region; jint _size; u1 _save_buf[_bufsize]; int sample(u1* save_buf) { if (_size <= _bufsize) { memcpy(save_buf, _region, _size); return _size; } else { // copy head and tail memcpy(&save_buf[0], _region, _bufsize/2); memcpy(&save_buf[_bufsize/2], _region + _size - _bufsize/2, _bufsize/2); return (_bufsize/2)*2; } } public: StableMemoryChecker(const void* region, jint size) { _region = (address) region; _size = size; sample(_save_buf); } bool verify() { u1 check_buf[sizeof(_save_buf)]; int check_size = sample(check_buf); return (0 == memcmp(_save_buf, check_buf, check_size)); } void set_region(const void* region) { _region = (address) region; } }; #endif // -------------------------------------------------------------------------- // Compute the hash value for a java.lang.String object which would // contain the characters passed in. This hash value is used for at // least two purposes. // // (a) As the hash value used by the StringTable for bucket selection // and comparison (stored in the HashtableEntry structures). This // is used in the String.intern() method. // // (b) As the hash value used by the String object itself, in // String.hashCode(). This value is normally calculate in Java code // in the String.hashCode method(), but is precomputed for String // objects in the shared archive file. // // For this reason, THIS ALGORITHM MUST MATCH String.hashCode(). int StringTable::hash_string(jchar* s, int len) { unsigned h = 0; while (len-- > 0) { h = 31*h + (unsigned) *s; s++; } return h; } StringTable* StringTable::_the_table = NULL; oop StringTable::lookup(int index, jchar* name, int len, unsigned int hash) { for (HashtableEntry* l = bucket(index); l != NULL; l = l->next()) { if (l->hash() == hash) { if (java_lang_String::equals(l->literal(), name, len)) { return l->literal(); } } } return NULL; } oop StringTable::basic_add(int index, Handle string_or_null, jchar* name, int len, unsigned int hashValue, TRAPS) { debug_only(StableMemoryChecker smc(name, len * sizeof(name[0]))); assert(!Universe::heap()->is_in_reserved(name) || GC_locker::is_active(), "proposed name of symbol must be stable"); Handle string; // try to reuse the string if possible if (!string_or_null.is_null() && string_or_null()->is_perm()) { string = string_or_null; } else { string = java_lang_String::create_tenured_from_unicode(name, len, CHECK_NULL); } // Allocation must be done before grapping the SymbolTable_lock lock MutexLocker ml(StringTable_lock, THREAD); assert(java_lang_String::equals(string(), name, len), "string must be properly initialized"); // Since look-up was done lock-free, we need to check if another // thread beat us in the race to insert the symbol. oop test = lookup(index, name, len, hashValue); // calls lookup(u1*, int) if (test != NULL) { // Entry already added return test; } HashtableEntry* entry = new_entry(hashValue, string()); add_entry(index, entry); return string(); } oop StringTable::lookup(symbolOop symbol) { ResourceMark rm; int length; jchar* chars = symbol->as_unicode(length); unsigned int hashValue = hash_string(chars, length); int index = the_table()->hash_to_index(hashValue); return the_table()->lookup(index, chars, length, hashValue); } oop StringTable::intern(Handle string_or_null, jchar* name, int len, TRAPS) { unsigned int hashValue = hash_string(name, len); int index = the_table()->hash_to_index(hashValue); oop string = the_table()->lookup(index, name, len, hashValue); // Found if (string != NULL) return string; // Otherwise, add to symbol to table return the_table()->basic_add(index, string_or_null, name, len, hashValue, CHECK_NULL); } oop StringTable::intern(symbolOop symbol, TRAPS) { if (symbol == NULL) return NULL; ResourceMark rm(THREAD); int length; jchar* chars = symbol->as_unicode(length); Handle string; oop result = intern(string, chars, length, CHECK_NULL); return result; } oop StringTable::intern(oop string, TRAPS) { if (string == NULL) return NULL; ResourceMark rm(THREAD); int length; Handle h_string (THREAD, string); jchar* chars = java_lang_String::as_unicode_string(string, length); oop result = intern(h_string, chars, length, CHECK_NULL); return result; } oop StringTable::intern(const char* utf8_string, TRAPS) { if (utf8_string == NULL) return NULL; ResourceMark rm(THREAD); int length = UTF8::unicode_length(utf8_string); jchar* chars = NEW_RESOURCE_ARRAY(jchar, length); UTF8::convert_to_unicode(utf8_string, chars, length); Handle string; oop result = intern(string, chars, length, CHECK_NULL); return result; } void StringTable::verify() { for (int i = 0; i < the_table()->table_size(); ++i) { HashtableEntry* p = the_table()->bucket(i); for ( ; p != NULL; p = p->next()) { oop s = p->literal(); guarantee(s != NULL, "interned string is NULL"); guarantee(s->is_perm(), "interned string not in permspace"); int length; jchar* chars = java_lang_String::as_unicode_string(s, length); unsigned int h = hash_string(chars, length); guarantee(p->hash() == h, "broken hash in string table entry"); guarantee(the_table()->hash_to_index(h) == i, "wrong index in string table"); } } }