| /* |
| * Copyright (c) 1997, 2020, 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/altHashing.hpp" |
| #include "classfile/compactHashtable.hpp" |
| #include "classfile/javaClasses.hpp" |
| #include "classfile/symbolTable.hpp" |
| #include "memory/allocation.inline.hpp" |
| #include "memory/dynamicArchive.hpp" |
| #include "memory/metaspaceClosure.hpp" |
| #include "memory/metaspaceShared.hpp" |
| #include "memory/resourceArea.hpp" |
| #include "oops/oop.inline.hpp" |
| #include "runtime/atomic.hpp" |
| #include "runtime/interfaceSupport.inline.hpp" |
| #include "runtime/timerTrace.hpp" |
| #include "services/diagnosticCommand.hpp" |
| #include "utilities/concurrentHashTable.inline.hpp" |
| #include "utilities/concurrentHashTableTasks.inline.hpp" |
| #include "utilities/utf8.hpp" |
| |
| // We used to not resize at all, so let's be conservative |
| // and not set it too short before we decide to resize, |
| // to match previous startup behavior |
| const double PREF_AVG_LIST_LEN = 8.0; |
| // 2^24 is max size, like StringTable. |
| const size_t END_SIZE = 24; |
| // If a chain gets to 100 something might be wrong |
| const size_t REHASH_LEN = 100; |
| |
| const size_t ON_STACK_BUFFER_LENGTH = 128; |
| |
| // -------------------------------------------------------------------------- |
| |
| inline bool symbol_equals_compact_hashtable_entry(Symbol* value, const char* key, int len) { |
| if (value->equals(key, len)) { |
| assert(value->is_permanent(), "must be shared"); |
| return true; |
| } else { |
| return false; |
| } |
| } |
| |
| static OffsetCompactHashtable< |
| const char*, Symbol*, |
| symbol_equals_compact_hashtable_entry |
| > _shared_table; |
| |
| static OffsetCompactHashtable< |
| const char*, Symbol*, |
| symbol_equals_compact_hashtable_entry |
| > _dynamic_shared_table; |
| |
| // -------------------------------------------------------------------------- |
| |
| typedef ConcurrentHashTable<SymbolTableConfig, mtSymbol> SymbolTableHash; |
| static SymbolTableHash* _local_table = NULL; |
| |
| volatile bool SymbolTable::_has_work = 0; |
| volatile bool SymbolTable::_needs_rehashing = false; |
| |
| // For statistics |
| static size_t _symbols_removed = 0; |
| static size_t _symbols_counted = 0; |
| static size_t _current_size = 0; |
| |
| static volatile size_t _items_count = 0; |
| static volatile bool _has_items_to_clean = false; |
| |
| |
| static volatile bool _alt_hash = false; |
| static volatile bool _lookup_shared_first = false; |
| |
| // Static arena for symbols that are not deallocated |
| Arena* SymbolTable::_arena = NULL; |
| |
| static juint murmur_seed = 0; |
| |
| static inline void log_trace_symboltable_helper(Symbol* sym, const char* msg) { |
| #ifndef PRODUCT |
| ResourceMark rm; |
| log_trace(symboltable)("%s [%s]", msg, sym->as_quoted_ascii()); |
| #endif // PRODUCT |
| } |
| |
| // Pick hashing algorithm. |
| static uintx hash_symbol(const char* s, int len, bool useAlt) { |
| return useAlt ? |
| AltHashing::murmur3_32(murmur_seed, (const jbyte*)s, len) : |
| java_lang_String::hash_code((const jbyte*)s, len); |
| } |
| |
| #if INCLUDE_CDS |
| static uintx hash_shared_symbol(const char* s, int len) { |
| return java_lang_String::hash_code((const jbyte*)s, len); |
| } |
| #endif |
| |
| class SymbolTableConfig : public AllStatic { |
| private: |
| public: |
| typedef Symbol* Value; // value of the Node in the hashtable |
| |
| static uintx get_hash(Value const& value, bool* is_dead) { |
| *is_dead = (value->refcount() == 0); |
| if (*is_dead) { |
| return 0; |
| } else { |
| return hash_symbol((const char*)value->bytes(), value->utf8_length(), _alt_hash); |
| } |
| } |
| // We use default allocation/deallocation but counted |
| static void* allocate_node(size_t size, Value const& value) { |
| SymbolTable::item_added(); |
| return AllocateHeap(size, mtSymbol); |
| } |
| static void free_node(void* memory, Value const& value) { |
| // We get here because #1 some threads lost a race to insert a newly created Symbol |
| // or #2 we're cleaning up unused symbol. |
| // If #1, then the symbol can be either permanent, |
| // or regular newly created one (refcount==1) |
| // If #2, then the symbol is dead (refcount==0) |
| assert(value->is_permanent() || (value->refcount() == 1) || (value->refcount() == 0), |
| "refcount %d", value->refcount()); |
| if (value->refcount() == 1) { |
| value->decrement_refcount(); |
| assert(value->refcount() == 0, "expected dead symbol"); |
| } |
| SymbolTable::delete_symbol(value); |
| FreeHeap(memory); |
| SymbolTable::item_removed(); |
| } |
| }; |
| |
| static size_t ceil_log2(size_t value) { |
| size_t ret; |
| for (ret = 1; ((size_t)1 << ret) < value; ++ret); |
| return ret; |
| } |
| |
| void SymbolTable::create_table () { |
| size_t start_size_log_2 = ceil_log2(SymbolTableSize); |
| _current_size = ((size_t)1) << start_size_log_2; |
| log_trace(symboltable)("Start size: " SIZE_FORMAT " (" SIZE_FORMAT ")", |
| _current_size, start_size_log_2); |
| _local_table = new SymbolTableHash(start_size_log_2, END_SIZE, REHASH_LEN); |
| |
| // Initialize the arena for global symbols, size passed in depends on CDS. |
| if (symbol_alloc_arena_size == 0) { |
| _arena = new (mtSymbol) Arena(mtSymbol); |
| } else { |
| _arena = new (mtSymbol) Arena(mtSymbol, symbol_alloc_arena_size); |
| } |
| } |
| |
| void SymbolTable::delete_symbol(Symbol* sym) { |
| if (sym->is_permanent()) { |
| MutexLocker ml(SymbolArena_lock, Mutex::_no_safepoint_check_flag); // Protect arena |
| // Deleting permanent symbol should not occur very often (insert race condition), |
| // so log it. |
| log_trace_symboltable_helper(sym, "Freeing permanent symbol"); |
| if (!arena()->Afree(sym, sym->size())) { |
| log_trace_symboltable_helper(sym, "Leaked permanent symbol"); |
| } |
| } else { |
| delete sym; |
| } |
| } |
| |
| void SymbolTable::reset_has_items_to_clean() { Atomic::store(&_has_items_to_clean, false); } |
| void SymbolTable::mark_has_items_to_clean() { Atomic::store(&_has_items_to_clean, true); } |
| bool SymbolTable::has_items_to_clean() { return Atomic::load(&_has_items_to_clean); } |
| |
| void SymbolTable::item_added() { |
| Atomic::inc(&_items_count); |
| } |
| |
| void SymbolTable::item_removed() { |
| Atomic::inc(&(_symbols_removed)); |
| Atomic::dec(&_items_count); |
| } |
| |
| double SymbolTable::get_load_factor() { |
| return (double)_items_count/_current_size; |
| } |
| |
| size_t SymbolTable::table_size() { |
| return ((size_t)1) << _local_table->get_size_log2(Thread::current()); |
| } |
| |
| void SymbolTable::trigger_cleanup() { |
| MutexLocker ml(Service_lock, Mutex::_no_safepoint_check_flag); |
| _has_work = true; |
| Service_lock->notify_all(); |
| } |
| |
| Symbol* SymbolTable::allocate_symbol(const char* name, int len, bool c_heap) { |
| assert (len <= Symbol::max_length(), "should be checked by caller"); |
| |
| Symbol* sym; |
| if (Arguments::is_dumping_archive()) { |
| c_heap = false; |
| } |
| if (c_heap) { |
| // refcount starts as 1 |
| sym = new (len) Symbol((const u1*)name, len, 1); |
| assert(sym != NULL, "new should call vm_exit_out_of_memory if C_HEAP is exhausted"); |
| } else { |
| // Allocate to global arena |
| MutexLocker ml(SymbolArena_lock, Mutex::_no_safepoint_check_flag); // Protect arena |
| sym = new (len, arena()) Symbol((const u1*)name, len, PERM_REFCOUNT); |
| } |
| return sym; |
| } |
| |
| class SymbolsDo : StackObj { |
| SymbolClosure *_cl; |
| public: |
| SymbolsDo(SymbolClosure *cl) : _cl(cl) {} |
| bool operator()(Symbol** value) { |
| assert(value != NULL, "expected valid value"); |
| assert(*value != NULL, "value should point to a symbol"); |
| _cl->do_symbol(value); |
| return true; |
| }; |
| }; |
| |
| class SharedSymbolIterator { |
| SymbolClosure* _symbol_closure; |
| public: |
| SharedSymbolIterator(SymbolClosure* f) : _symbol_closure(f) {} |
| void do_value(Symbol* symbol) { |
| _symbol_closure->do_symbol(&symbol); |
| } |
| }; |
| |
| // Call function for all symbols in the symbol table. |
| void SymbolTable::symbols_do(SymbolClosure *cl) { |
| // all symbols from shared table |
| SharedSymbolIterator iter(cl); |
| _shared_table.iterate(&iter); |
| _dynamic_shared_table.iterate(&iter); |
| |
| // all symbols from the dynamic table |
| SymbolsDo sd(cl); |
| if (!_local_table->try_scan(Thread::current(), sd)) { |
| log_info(symboltable)("symbols_do unavailable at this moment"); |
| } |
| } |
| |
| class MetaspacePointersDo : StackObj { |
| MetaspaceClosure *_it; |
| public: |
| MetaspacePointersDo(MetaspaceClosure *it) : _it(it) {} |
| bool operator()(Symbol** value) { |
| assert(value != NULL, "expected valid value"); |
| assert(*value != NULL, "value should point to a symbol"); |
| _it->push(value); |
| return true; |
| }; |
| }; |
| |
| void SymbolTable::metaspace_pointers_do(MetaspaceClosure* it) { |
| Arguments::assert_is_dumping_archive(); |
| MetaspacePointersDo mpd(it); |
| _local_table->do_safepoint_scan(mpd); |
| } |
| |
| Symbol* SymbolTable::lookup_dynamic(const char* name, |
| int len, unsigned int hash) { |
| Symbol* sym = do_lookup(name, len, hash); |
| assert((sym == NULL) || sym->refcount() != 0, "refcount must not be zero"); |
| return sym; |
| } |
| |
| #if INCLUDE_CDS |
| Symbol* SymbolTable::lookup_shared(const char* name, |
| int len, unsigned int hash) { |
| Symbol* sym = NULL; |
| if (!_shared_table.empty()) { |
| if (_alt_hash) { |
| // hash_code parameter may use alternate hashing algorithm but the shared table |
| // always uses the same original hash code. |
| hash = hash_shared_symbol(name, len); |
| } |
| sym = _shared_table.lookup(name, hash, len); |
| if (sym == NULL && DynamicArchive::is_mapped()) { |
| sym = _dynamic_shared_table.lookup(name, hash, len); |
| } |
| } |
| return sym; |
| } |
| #endif |
| |
| Symbol* SymbolTable::lookup_common(const char* name, |
| int len, unsigned int hash) { |
| Symbol* sym; |
| if (_lookup_shared_first) { |
| sym = lookup_shared(name, len, hash); |
| if (sym == NULL) { |
| _lookup_shared_first = false; |
| sym = lookup_dynamic(name, len, hash); |
| } |
| } else { |
| sym = lookup_dynamic(name, len, hash); |
| if (sym == NULL) { |
| sym = lookup_shared(name, len, hash); |
| if (sym != NULL) { |
| _lookup_shared_first = true; |
| } |
| } |
| } |
| return sym; |
| } |
| |
| Symbol* SymbolTable::new_symbol(const char* name, int len) { |
| unsigned int hash = hash_symbol(name, len, _alt_hash); |
| Symbol* sym = lookup_common(name, len, hash); |
| if (sym == NULL) { |
| sym = do_add_if_needed(name, len, hash, true); |
| } |
| assert(sym->refcount() != 0, "lookup should have incremented the count"); |
| assert(sym->equals(name, len), "symbol must be properly initialized"); |
| return sym; |
| } |
| |
| Symbol* SymbolTable::new_symbol(const Symbol* sym, int begin, int end) { |
| assert(begin <= end && end <= sym->utf8_length(), "just checking"); |
| assert(sym->refcount() != 0, "require a valid symbol"); |
| const char* name = (const char*)sym->base() + begin; |
| int len = end - begin; |
| unsigned int hash = hash_symbol(name, len, _alt_hash); |
| Symbol* found = lookup_common(name, len, hash); |
| if (found == NULL) { |
| found = do_add_if_needed(name, len, hash, true); |
| } |
| return found; |
| } |
| |
| class SymbolTableLookup : StackObj { |
| private: |
| Thread* _thread; |
| uintx _hash; |
| int _len; |
| const char* _str; |
| public: |
| SymbolTableLookup(const char* key, int len, uintx hash) |
| : _hash(hash), _len(len), _str(key) {} |
| uintx get_hash() const { |
| return _hash; |
| } |
| bool equals(Symbol** value, bool* is_dead) { |
| assert(value != NULL, "expected valid value"); |
| assert(*value != NULL, "value should point to a symbol"); |
| Symbol *sym = *value; |
| if (sym->equals(_str, _len)) { |
| if (sym->try_increment_refcount()) { |
| // something is referencing this symbol now. |
| return true; |
| } else { |
| assert(sym->refcount() == 0, "expected dead symbol"); |
| *is_dead = true; |
| return false; |
| } |
| } else { |
| *is_dead = (sym->refcount() == 0); |
| return false; |
| } |
| } |
| }; |
| |
| class SymbolTableGet : public StackObj { |
| Symbol* _return; |
| public: |
| SymbolTableGet() : _return(NULL) {} |
| void operator()(Symbol** value) { |
| assert(value != NULL, "expected valid value"); |
| assert(*value != NULL, "value should point to a symbol"); |
| _return = *value; |
| } |
| Symbol* get_res_sym() const { |
| return _return; |
| } |
| }; |
| |
| Symbol* SymbolTable::do_lookup(const char* name, int len, uintx hash) { |
| Thread* thread = Thread::current(); |
| SymbolTableLookup lookup(name, len, hash); |
| SymbolTableGet stg; |
| bool rehash_warning = false; |
| _local_table->get(thread, lookup, stg, &rehash_warning); |
| update_needs_rehash(rehash_warning); |
| Symbol* sym = stg.get_res_sym(); |
| assert((sym == NULL) || sym->refcount() != 0, "found dead symbol"); |
| return sym; |
| } |
| |
| Symbol* SymbolTable::lookup_only(const char* name, int len, unsigned int& hash) { |
| hash = hash_symbol(name, len, _alt_hash); |
| return lookup_common(name, len, hash); |
| } |
| |
| // Suggestion: Push unicode-based lookup all the way into the hashing |
| // and probing logic, so there is no need for convert_to_utf8 until |
| // an actual new Symbol* is created. |
| Symbol* SymbolTable::new_symbol(const jchar* name, int utf16_length) { |
| int utf8_length = UNICODE::utf8_length((jchar*) name, utf16_length); |
| char stack_buf[ON_STACK_BUFFER_LENGTH]; |
| if (utf8_length < (int) sizeof(stack_buf)) { |
| char* chars = stack_buf; |
| UNICODE::convert_to_utf8(name, utf16_length, chars); |
| return new_symbol(chars, utf8_length); |
| } else { |
| ResourceMark rm; |
| char* chars = NEW_RESOURCE_ARRAY(char, utf8_length + 1); |
| UNICODE::convert_to_utf8(name, utf16_length, chars); |
| return new_symbol(chars, utf8_length); |
| } |
| } |
| |
| Symbol* SymbolTable::lookup_only_unicode(const jchar* name, int utf16_length, |
| unsigned int& hash) { |
| int utf8_length = UNICODE::utf8_length((jchar*) name, utf16_length); |
| char stack_buf[ON_STACK_BUFFER_LENGTH]; |
| if (utf8_length < (int) sizeof(stack_buf)) { |
| char* chars = stack_buf; |
| UNICODE::convert_to_utf8(name, utf16_length, chars); |
| return lookup_only(chars, utf8_length, hash); |
| } else { |
| ResourceMark rm; |
| char* chars = NEW_RESOURCE_ARRAY(char, utf8_length + 1); |
| UNICODE::convert_to_utf8(name, utf16_length, chars); |
| return lookup_only(chars, utf8_length, hash); |
| } |
| } |
| |
| void SymbolTable::new_symbols(ClassLoaderData* loader_data, const constantPoolHandle& cp, |
| int names_count, const char** names, int* lengths, |
| int* cp_indices, unsigned int* hashValues) { |
| bool c_heap = !loader_data->is_the_null_class_loader_data(); |
| for (int i = 0; i < names_count; i++) { |
| const char *name = names[i]; |
| int len = lengths[i]; |
| unsigned int hash = hashValues[i]; |
| assert(lookup_shared(name, len, hash) == NULL, "must have checked already"); |
| Symbol* sym = do_add_if_needed(name, len, hash, c_heap); |
| assert(sym->refcount() != 0, "lookup should have incremented the count"); |
| cp->symbol_at_put(cp_indices[i], sym); |
| } |
| } |
| |
| Symbol* SymbolTable::do_add_if_needed(const char* name, int len, uintx hash, bool heap) { |
| SymbolTableLookup lookup(name, len, hash); |
| SymbolTableGet stg; |
| bool clean_hint = false; |
| bool rehash_warning = false; |
| Symbol* sym = NULL; |
| Thread* THREAD = Thread::current(); |
| |
| do { |
| // Callers have looked up the symbol once, insert the symbol. |
| sym = allocate_symbol(name, len, heap); |
| if (_local_table->insert(THREAD, lookup, sym, &rehash_warning, &clean_hint)) { |
| break; |
| } |
| // In case another thread did a concurrent add, return value already in the table. |
| // This could fail if the symbol got deleted concurrently, so loop back until success. |
| if (_local_table->get(THREAD, lookup, stg, &rehash_warning)) { |
| sym = stg.get_res_sym(); |
| break; |
| } |
| } while(true); |
| |
| update_needs_rehash(rehash_warning); |
| |
| if (clean_hint) { |
| mark_has_items_to_clean(); |
| check_concurrent_work(); |
| } |
| |
| assert((sym == NULL) || sym->refcount() != 0, "found dead symbol"); |
| return sym; |
| } |
| |
| Symbol* SymbolTable::new_permanent_symbol(const char* name) { |
| unsigned int hash = 0; |
| int len = (int)strlen(name); |
| Symbol* sym = SymbolTable::lookup_only(name, len, hash); |
| if (sym == NULL) { |
| sym = do_add_if_needed(name, len, hash, false); |
| } |
| if (!sym->is_permanent()) { |
| sym->make_permanent(); |
| log_trace_symboltable_helper(sym, "Asked for a permanent symbol, but got a regular one"); |
| } |
| return sym; |
| } |
| |
| struct SizeFunc : StackObj { |
| size_t operator()(Symbol** value) { |
| assert(value != NULL, "expected valid value"); |
| assert(*value != NULL, "value should point to a symbol"); |
| return (*value)->size() * HeapWordSize; |
| }; |
| }; |
| |
| TableStatistics SymbolTable::get_table_statistics() { |
| static TableStatistics ts; |
| SizeFunc sz; |
| ts = _local_table->statistics_get(Thread::current(), sz, ts); |
| return ts; |
| } |
| |
| void SymbolTable::print_table_statistics(outputStream* st, |
| const char* table_name) { |
| SizeFunc sz; |
| _local_table->statistics_to(Thread::current(), sz, st, table_name); |
| } |
| |
| // Verification |
| class VerifySymbols : StackObj { |
| public: |
| bool operator()(Symbol** value) { |
| guarantee(value != NULL, "expected valid value"); |
| guarantee(*value != NULL, "value should point to a symbol"); |
| Symbol* sym = *value; |
| guarantee(sym->equals((const char*)sym->bytes(), sym->utf8_length()), |
| "symbol must be internally consistent"); |
| return true; |
| }; |
| }; |
| |
| void SymbolTable::verify() { |
| Thread* thr = Thread::current(); |
| VerifySymbols vs; |
| if (!_local_table->try_scan(thr, vs)) { |
| log_info(symboltable)("verify unavailable at this moment"); |
| } |
| } |
| |
| // Dumping |
| class DumpSymbol : StackObj { |
| Thread* _thr; |
| outputStream* _st; |
| public: |
| DumpSymbol(Thread* thr, outputStream* st) : _thr(thr), _st(st) {} |
| bool operator()(Symbol** value) { |
| assert(value != NULL, "expected valid value"); |
| assert(*value != NULL, "value should point to a symbol"); |
| Symbol* sym = *value; |
| const char* utf8_string = (const char*)sym->bytes(); |
| int utf8_length = sym->utf8_length(); |
| _st->print("%d %d: ", utf8_length, sym->refcount()); |
| HashtableTextDump::put_utf8(_st, utf8_string, utf8_length); |
| _st->cr(); |
| return true; |
| }; |
| }; |
| |
| void SymbolTable::dump(outputStream* st, bool verbose) { |
| if (!verbose) { |
| print_table_statistics(st, "SymbolTable"); |
| } else { |
| Thread* thr = Thread::current(); |
| ResourceMark rm(thr); |
| st->print_cr("VERSION: 1.1"); |
| DumpSymbol ds(thr, st); |
| if (!_local_table->try_scan(thr, ds)) { |
| log_info(symboltable)("dump unavailable at this moment"); |
| } |
| } |
| } |
| |
| #if INCLUDE_CDS |
| struct CopyToArchive : StackObj { |
| CompactHashtableWriter* _writer; |
| CopyToArchive(CompactHashtableWriter* writer) : _writer(writer) {} |
| bool operator()(Symbol** value) { |
| assert(value != NULL, "expected valid value"); |
| assert(*value != NULL, "value should point to a symbol"); |
| Symbol* sym = *value; |
| unsigned int fixed_hash = hash_shared_symbol((const char*)sym->bytes(), sym->utf8_length()); |
| assert(fixed_hash == hash_symbol((const char*)sym->bytes(), sym->utf8_length(), false), |
| "must not rehash during dumping"); |
| if (DynamicDumpSharedSpaces) { |
| sym = DynamicArchive::original_to_target(sym); |
| } |
| _writer->add(fixed_hash, MetaspaceShared::object_delta_u4(sym)); |
| return true; |
| } |
| }; |
| |
| void SymbolTable::copy_shared_symbol_table(CompactHashtableWriter* writer) { |
| CopyToArchive copy(writer); |
| _local_table->do_safepoint_scan(copy); |
| } |
| |
| size_t SymbolTable::estimate_size_for_archive() { |
| return CompactHashtableWriter::estimate_size(int(_items_count)); |
| } |
| |
| void SymbolTable::write_to_archive(bool is_static_archive) { |
| CompactHashtableWriter writer(int(_items_count), |
| &MetaspaceShared::stats()->symbol); |
| copy_shared_symbol_table(&writer); |
| if (is_static_archive) { |
| _shared_table.reset(); |
| writer.dump(&_shared_table, "symbol"); |
| |
| // Verify table is correct |
| Symbol* sym = vmSymbols::java_lang_Object(); |
| const char* name = (const char*)sym->bytes(); |
| int len = sym->utf8_length(); |
| unsigned int hash = hash_symbol(name, len, _alt_hash); |
| assert(sym == _shared_table.lookup(name, hash, len), "sanity"); |
| } else { |
| _dynamic_shared_table.reset(); |
| writer.dump(&_dynamic_shared_table, "symbol"); |
| } |
| } |
| |
| void SymbolTable::serialize_shared_table_header(SerializeClosure* soc, |
| bool is_static_archive) { |
| OffsetCompactHashtable<const char*, Symbol*, symbol_equals_compact_hashtable_entry> * table; |
| if (is_static_archive) { |
| table = &_shared_table; |
| } else { |
| table = &_dynamic_shared_table; |
| } |
| table->serialize_header(soc); |
| if (soc->writing()) { |
| // Sanity. Make sure we don't use the shared table at dump time |
| table->reset(); |
| } |
| } |
| #endif //INCLUDE_CDS |
| |
| // Concurrent work |
| void SymbolTable::grow(JavaThread* jt) { |
| SymbolTableHash::GrowTask gt(_local_table); |
| if (!gt.prepare(jt)) { |
| return; |
| } |
| log_trace(symboltable)("Started to grow"); |
| { |
| TraceTime timer("Grow", TRACETIME_LOG(Debug, symboltable, perf)); |
| while (gt.do_task(jt)) { |
| gt.pause(jt); |
| { |
| ThreadBlockInVM tbivm(jt); |
| } |
| gt.cont(jt); |
| } |
| } |
| gt.done(jt); |
| _current_size = table_size(); |
| log_debug(symboltable)("Grown to size:" SIZE_FORMAT, _current_size); |
| } |
| |
| struct SymbolTableDoDelete : StackObj { |
| size_t _deleted; |
| SymbolTableDoDelete() : _deleted(0) {} |
| void operator()(Symbol** value) { |
| assert(value != NULL, "expected valid value"); |
| assert(*value != NULL, "value should point to a symbol"); |
| Symbol *sym = *value; |
| assert(sym->refcount() == 0, "refcount"); |
| _deleted++; |
| } |
| }; |
| |
| struct SymbolTableDeleteCheck : StackObj { |
| size_t _processed; |
| SymbolTableDeleteCheck() : _processed(0) {} |
| bool operator()(Symbol** value) { |
| assert(value != NULL, "expected valid value"); |
| assert(*value != NULL, "value should point to a symbol"); |
| _processed++; |
| Symbol *sym = *value; |
| return (sym->refcount() == 0); |
| } |
| }; |
| |
| void SymbolTable::clean_dead_entries(JavaThread* jt) { |
| SymbolTableHash::BulkDeleteTask bdt(_local_table); |
| if (!bdt.prepare(jt)) { |
| return; |
| } |
| |
| SymbolTableDeleteCheck stdc; |
| SymbolTableDoDelete stdd; |
| { |
| TraceTime timer("Clean", TRACETIME_LOG(Debug, symboltable, perf)); |
| while (bdt.do_task(jt, stdc, stdd)) { |
| bdt.pause(jt); |
| { |
| ThreadBlockInVM tbivm(jt); |
| } |
| bdt.cont(jt); |
| } |
| reset_has_items_to_clean(); |
| bdt.done(jt); |
| } |
| |
| Atomic::add(&_symbols_counted, stdc._processed); |
| |
| log_debug(symboltable)("Cleaned " SIZE_FORMAT " of " SIZE_FORMAT, |
| stdd._deleted, stdc._processed); |
| } |
| |
| void SymbolTable::check_concurrent_work() { |
| if (_has_work) { |
| return; |
| } |
| // We should clean/resize if we have |
| // more items than preferred load factor or |
| // more dead items than water mark. |
| if (has_items_to_clean() || (get_load_factor() > PREF_AVG_LIST_LEN)) { |
| log_debug(symboltable)("Concurrent work triggered, load factor: %f, items to clean: %s", |
| get_load_factor(), has_items_to_clean() ? "true" : "false"); |
| trigger_cleanup(); |
| } |
| } |
| |
| void SymbolTable::do_concurrent_work(JavaThread* jt) { |
| double load_factor = get_load_factor(); |
| log_debug(symboltable, perf)("Concurrent work, live factor: %g", load_factor); |
| // We prefer growing, since that also removes dead items |
| if (load_factor > PREF_AVG_LIST_LEN && !_local_table->is_max_size_reached()) { |
| grow(jt); |
| } else { |
| clean_dead_entries(jt); |
| } |
| _has_work = false; |
| } |
| |
| // Rehash |
| bool SymbolTable::do_rehash() { |
| if (!_local_table->is_safepoint_safe()) { |
| return false; |
| } |
| |
| // We use current size |
| size_t new_size = _local_table->get_size_log2(Thread::current()); |
| SymbolTableHash* new_table = new SymbolTableHash(new_size, END_SIZE, REHASH_LEN); |
| // Use alt hash from now on |
| _alt_hash = true; |
| if (!_local_table->try_move_nodes_to(Thread::current(), new_table)) { |
| _alt_hash = false; |
| delete new_table; |
| return false; |
| } |
| |
| // free old table |
| delete _local_table; |
| _local_table = new_table; |
| |
| return true; |
| } |
| |
| void SymbolTable::rehash_table() { |
| static bool rehashed = false; |
| log_debug(symboltable)("Table imbalanced, rehashing called."); |
| |
| // Grow instead of rehash. |
| if (get_load_factor() > PREF_AVG_LIST_LEN && |
| !_local_table->is_max_size_reached()) { |
| log_debug(symboltable)("Choosing growing over rehashing."); |
| trigger_cleanup(); |
| _needs_rehashing = false; |
| return; |
| } |
| |
| // Already rehashed. |
| if (rehashed) { |
| log_warning(symboltable)("Rehashing already done, still long lists."); |
| trigger_cleanup(); |
| _needs_rehashing = false; |
| return; |
| } |
| |
| murmur_seed = AltHashing::compute_seed(); |
| |
| if (do_rehash()) { |
| rehashed = true; |
| } else { |
| log_info(symboltable)("Resizes in progress rehashing skipped."); |
| } |
| |
| _needs_rehashing = false; |
| } |
| |
| //--------------------------------------------------------------------------- |
| // Non-product code |
| |
| #ifndef PRODUCT |
| |
| class HistogramIterator : StackObj { |
| public: |
| static const size_t results_length = 100; |
| size_t counts[results_length]; |
| size_t sizes[results_length]; |
| size_t total_size; |
| size_t total_count; |
| size_t total_length; |
| size_t max_length; |
| size_t out_of_range_count; |
| size_t out_of_range_size; |
| HistogramIterator() : total_size(0), total_count(0), total_length(0), |
| max_length(0), out_of_range_count(0), out_of_range_size(0) { |
| // initialize results to zero |
| for (size_t i = 0; i < results_length; i++) { |
| counts[i] = 0; |
| sizes[i] = 0; |
| } |
| } |
| bool operator()(Symbol** value) { |
| assert(value != NULL, "expected valid value"); |
| assert(*value != NULL, "value should point to a symbol"); |
| Symbol* sym = *value; |
| size_t size = sym->size(); |
| size_t len = sym->utf8_length(); |
| if (len < results_length) { |
| counts[len]++; |
| sizes[len] += size; |
| } else { |
| out_of_range_count++; |
| out_of_range_size += size; |
| } |
| total_count++; |
| total_size += size; |
| total_length += len; |
| max_length = MAX2(max_length, len); |
| |
| return true; |
| }; |
| }; |
| |
| void SymbolTable::print_histogram() { |
| HistogramIterator hi; |
| _local_table->do_scan(Thread::current(), hi); |
| tty->print_cr("Symbol Table Histogram:"); |
| tty->print_cr(" Total number of symbols " SIZE_FORMAT_W(7), hi.total_count); |
| tty->print_cr(" Total size in memory " SIZE_FORMAT_W(7) "K", |
| (hi.total_size * wordSize) / 1024); |
| tty->print_cr(" Total counted " SIZE_FORMAT_W(7), _symbols_counted); |
| tty->print_cr(" Total removed " SIZE_FORMAT_W(7), _symbols_removed); |
| if (_symbols_counted > 0) { |
| tty->print_cr(" Percent removed %3.2f", |
| ((float)_symbols_removed / _symbols_counted) * 100); |
| } |
| tty->print_cr(" Reference counts " SIZE_FORMAT_W(7), Symbol::_total_count); |
| tty->print_cr(" Symbol arena used " SIZE_FORMAT_W(7) "K", arena()->used() / 1024); |
| tty->print_cr(" Symbol arena size " SIZE_FORMAT_W(7) "K", arena()->size_in_bytes() / 1024); |
| tty->print_cr(" Total symbol length " SIZE_FORMAT_W(7), hi.total_length); |
| tty->print_cr(" Maximum symbol length " SIZE_FORMAT_W(7), hi.max_length); |
| tty->print_cr(" Average symbol length %7.2f", ((float)hi.total_length / hi.total_count)); |
| tty->print_cr(" Symbol length histogram:"); |
| tty->print_cr(" %6s %10s %10s", "Length", "#Symbols", "Size"); |
| for (size_t i = 0; i < hi.results_length; i++) { |
| if (hi.counts[i] > 0) { |
| tty->print_cr(" " SIZE_FORMAT_W(6) " " SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10) "K", |
| i, hi.counts[i], (hi.sizes[i] * wordSize) / 1024); |
| } |
| } |
| tty->print_cr(" >=" SIZE_FORMAT_W(6) " " SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10) "K\n", |
| hi.results_length, hi.out_of_range_count, (hi.out_of_range_size*wordSize) / 1024); |
| } |
| #endif // PRODUCT |
| |
| // Utility for dumping symbols |
| SymboltableDCmd::SymboltableDCmd(outputStream* output, bool heap) : |
| DCmdWithParser(output, heap), |
| _verbose("-verbose", "Dump the content of each symbol in the table", |
| "BOOLEAN", false, "false") { |
| _dcmdparser.add_dcmd_option(&_verbose); |
| } |
| |
| void SymboltableDCmd::execute(DCmdSource source, TRAPS) { |
| VM_DumpHashtable dumper(output(), VM_DumpHashtable::DumpSymbols, |
| _verbose.value()); |
| VMThread::execute(&dumper); |
| } |
| |
| int SymboltableDCmd::num_arguments() { |
| ResourceMark rm; |
| SymboltableDCmd* dcmd = new SymboltableDCmd(NULL, false); |
| if (dcmd != NULL) { |
| DCmdMark mark(dcmd); |
| return dcmd->_dcmdparser.num_arguments(); |
| } else { |
| return 0; |
| } |
| } |