duke@435: /* tschatzl@8766: * Copyright (c) 2003, 2017, Oracle and/or its affiliates. All rights reserved. duke@435: * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. duke@435: * duke@435: * This code is free software; you can redistribute it and/or modify it duke@435: * under the terms of the GNU General Public License version 2 only, as duke@435: * published by the Free Software Foundation. duke@435: * duke@435: * This code is distributed in the hope that it will be useful, but WITHOUT duke@435: * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or duke@435: * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License duke@435: * version 2 for more details (a copy is included in the LICENSE file that duke@435: * accompanied this code). duke@435: * duke@435: * You should have received a copy of the GNU General Public License version duke@435: * 2 along with this work; if not, write to the Free Software Foundation, duke@435: * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. duke@435: * trims@1907: * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA trims@1907: * or visit www.oracle.com if you need additional information or have any trims@1907: * questions. duke@435: * duke@435: */ duke@435: stefank@2314: #include "precompiled.hpp" coleenp@3904: #include "classfile/altHashing.hpp" coleenp@3904: #include "classfile/javaClasses.hpp" stefank@2314: #include "memory/allocation.inline.hpp" coleenp@3875: #include "memory/filemap.hpp" stefank@2314: #include "memory/resourceArea.hpp" stefank@2314: #include "oops/oop.inline.hpp" stefank@2314: #include "runtime/safepoint.hpp" stefank@2314: #include "utilities/dtrace.hpp" stefank@2314: #include "utilities/hashtable.hpp" stefank@2314: #include "utilities/hashtable.inline.hpp" iklam@5144: #include "utilities/numberSeq.hpp" duke@435: coleenp@2497: mgerdin@7207: // This hashtable is implemented as an open hash table with a fixed number of buckets. duke@435: mgerdin@7207: template BasicHashtableEntry* BasicHashtable::new_entry_free_list() { mgerdin@7207: BasicHashtableEntry* entry = NULL; mgerdin@7207: if (_free_list != NULL) { duke@435: entry = _free_list; duke@435: _free_list = _free_list->next(); mgerdin@7207: } mgerdin@7207: return entry; mgerdin@7207: } mgerdin@7207: mgerdin@7207: // HashtableEntrys are allocated in blocks to reduce the space overhead. mgerdin@7207: template BasicHashtableEntry* BasicHashtable::new_entry(unsigned int hashValue) { mgerdin@7207: BasicHashtableEntry* entry = new_entry_free_list(); mgerdin@7207: mgerdin@7207: if (entry == NULL) { jrose@867: if (_first_free_entry + _entry_size >= _end_block) { jrose@867: int block_size = MIN2(512, MAX2((int)_table_size / 2, (int)_number_of_entries)); duke@435: int len = _entry_size * block_size; jrose@867: len = 1 << log2_intptr(len); // round down to power of 2 jrose@867: assert(len >= _entry_size, ""); zgu@3900: _first_free_entry = NEW_C_HEAP_ARRAY2(char, len, F, CURRENT_PC); duke@435: _end_block = _first_free_entry + len; duke@435: } zgu@3900: entry = (BasicHashtableEntry*)_first_free_entry; duke@435: _first_free_entry += _entry_size; duke@435: } duke@435: jrose@867: assert(_entry_size % HeapWordSize == 0, ""); duke@435: entry->set_hash(hashValue); duke@435: return entry; duke@435: } duke@435: duke@435: zgu@3900: template HashtableEntry* Hashtable::new_entry(unsigned int hashValue, T obj) { zgu@3900: HashtableEntry* entry; duke@435: zgu@3900: entry = (HashtableEntry*)BasicHashtable::new_entry(hashValue); coleenp@2497: entry->set_literal(obj); duke@435: return entry; duke@435: } duke@435: coleenp@3865: // Check to see if the hashtable is unbalanced. The caller set a flag to coleenp@3865: // rehash at the next safepoint. If this bucket is 60 times greater than the coleenp@3865: // expected average bucket length, it's an unbalanced hashtable. coleenp@3865: // This is somewhat an arbitrary heuristic but if one bucket gets to coleenp@3865: // rehash_count which is currently 100, there's probably something wrong. coleenp@3865: mgerdin@7207: template bool RehashableHashtable::check_rehash_table(int count) { mgerdin@7207: assert(this->table_size() != 0, "underflow"); mgerdin@7207: if (count > (((double)this->number_of_entries()/(double)this->table_size())*rehash_multiple)) { coleenp@3865: // Set a flag for the next safepoint, which should be at some guaranteed coleenp@3865: // safepoint interval. coleenp@3865: return true; coleenp@3865: } coleenp@3865: return false; coleenp@3865: } coleenp@3865: mgerdin@7207: template juint RehashableHashtable::_seed = 0; coleenp@3904: coleenp@3865: // Create a new table and using alternate hash code, populate the new table coleenp@3865: // with the existing elements. This can be used to change the hash code coleenp@3865: // and could in the future change the size of the table. coleenp@3865: mgerdin@7207: template void RehashableHashtable::move_to(RehashableHashtable* new_table) { coleenp@3904: coleenp@3904: // Initialize the global seed for hashing. coleenp@3904: _seed = AltHashing::compute_seed(); coleenp@3904: assert(seed() != 0, "shouldn't be zero"); coleenp@3904: coleenp@3904: int saved_entry_count = this->number_of_entries(); coleenp@3865: coleenp@3865: // Iterate through the table and create a new entry for the new table coleenp@3865: for (int i = 0; i < new_table->table_size(); ++i) { mgerdin@7207: for (HashtableEntry* p = this->bucket(i); p != NULL; ) { zgu@3900: HashtableEntry* next = p->next(); coleenp@3865: T string = p->literal(); coleenp@3865: // Use alternate hashing algorithm on the symbol in the first table coleenp@4037: unsigned int hashValue = string->new_hash(seed()); coleenp@3865: // Get a new index relative to the new table (can also change size) coleenp@3865: int index = new_table->hash_to_index(hashValue); coleenp@3865: p->set_hash(hashValue); coleenp@3875: // Keep the shared bit in the Hashtable entry to indicate that this entry coleenp@3875: // can't be deleted. The shared bit is the LSB in the _next field so coleenp@3875: // walking the hashtable past these entries requires coleenp@3875: // BasicHashtableEntry::make_ptr() call. coleenp@3875: bool keep_shared = p->is_shared(); andrew@3963: this->unlink_entry(p); coleenp@3865: new_table->add_entry(index, p); coleenp@3875: if (keep_shared) { coleenp@3875: p->set_shared(); coleenp@3875: } coleenp@3865: p = next; coleenp@3865: } coleenp@3865: } coleenp@3865: // give the new table the free list as well coleenp@3865: new_table->copy_freelist(this); coleenp@3865: assert(new_table->number_of_entries() == saved_entry_count, "lost entry on dictionary copy?"); coleenp@3865: coleenp@3865: // Destroy memory used by the buckets in the hashtable. The memory coleenp@3865: // for the elements has been used in a new table and is not coleenp@3865: // destroyed. The memory reuse will benefit resizing the SystemDictionary coleenp@3865: // to avoid a memory allocation spike at safepoint. zgu@3900: BasicHashtable::free_buckets(); coleenp@3865: } coleenp@3865: zgu@3900: template void BasicHashtable::free_buckets() { coleenp@3875: if (NULL != _buckets) { coleenp@3875: // Don't delete the buckets in the shared space. They aren't coleenp@3875: // allocated by os::malloc coleenp@3875: if (!UseSharedSpaces || coleenp@3875: !FileMapInfo::current_info()->is_in_shared_space(_buckets)) { zgu@3900: FREE_C_HEAP_ARRAY(HashtableBucket, _buckets, F); coleenp@3875: } coleenp@3875: _buckets = NULL; coleenp@3875: } coleenp@3875: } coleenp@3875: coleenp@3875: duke@435: // Reverse the order of elements in the hash buckets. duke@435: zgu@3900: template void BasicHashtable::reverse() { duke@435: duke@435: for (int i = 0; i < _table_size; ++i) { zgu@3900: BasicHashtableEntry* new_list = NULL; zgu@3900: BasicHashtableEntry* p = bucket(i); duke@435: while (p != NULL) { zgu@3900: BasicHashtableEntry* next = p->next(); duke@435: p->set_next(new_list); duke@435: new_list = p; duke@435: p = next; duke@435: } duke@435: *bucket_addr(i) = new_list; duke@435: } duke@435: } duke@435: tschatzl@8766: template void BasicHashtable::BucketUnlinkContext::free_entry(BasicHashtableEntry* entry) { tschatzl@8766: entry->set_next(_removed_head); tschatzl@8766: _removed_head = entry; tschatzl@8766: if (_removed_tail == NULL) { tschatzl@8766: _removed_tail = entry; tschatzl@8766: } tschatzl@8766: _num_removed++; tschatzl@8766: } tschatzl@8766: tschatzl@8766: template void BasicHashtable::bulk_free_entries(BucketUnlinkContext* context) { tschatzl@8766: if (context->_num_removed == 0) { tschatzl@8766: assert(context->_removed_head == NULL && context->_removed_tail == NULL, tschatzl@8766: err_msg("Zero entries in the unlink context, but elements linked from " PTR_FORMAT " to " PTR_FORMAT, tschatzl@8766: p2i(context->_removed_head), p2i(context->_removed_tail))); tschatzl@8766: return; tschatzl@8766: } tschatzl@8766: tschatzl@8766: // MT-safe add of the list of BasicHashTableEntrys from the context to the free list. tschatzl@8766: BasicHashtableEntry* current = _free_list; tschatzl@8766: while (true) { tschatzl@8766: context->_removed_tail->set_next(current); tschatzl@8766: BasicHashtableEntry* old = (BasicHashtableEntry*)Atomic::cmpxchg_ptr(context->_removed_head, &_free_list, current); tschatzl@8766: if (old == current) { tschatzl@8766: break; tschatzl@8766: } tschatzl@8766: current = old; tschatzl@8766: } tschatzl@8766: Atomic::add(-context->_num_removed, &_number_of_entries); tschatzl@8766: } duke@435: duke@435: // Copy the table to the shared space. duke@435: zgu@3900: template void BasicHashtable::copy_table(char** top, char* end) { duke@435: duke@435: // Dump the hash table entries. duke@435: duke@435: intptr_t *plen = (intptr_t*)(*top); duke@435: *top += sizeof(*plen); duke@435: duke@435: int i; duke@435: for (i = 0; i < _table_size; ++i) { zgu@3900: for (BasicHashtableEntry** p = _buckets[i].entry_addr(); duke@435: *p != NULL; duke@435: p = (*p)->next_addr()) { duke@435: if (*top + entry_size() > end) { coleenp@2497: report_out_of_shared_space(SharedMiscData); duke@435: } zgu@3900: *p = (BasicHashtableEntry*)memcpy(*top, *p, entry_size()); duke@435: *top += entry_size(); duke@435: } duke@435: } duke@435: *plen = (char*)(*top) - (char*)plen - sizeof(*plen); duke@435: duke@435: // Set the shared bit. duke@435: duke@435: for (i = 0; i < _table_size; ++i) { zgu@3900: for (BasicHashtableEntry* p = bucket(i); p != NULL; p = p->next()) { duke@435: p->set_shared(); duke@435: } duke@435: } duke@435: } duke@435: duke@435: duke@435: duke@435: // Reverse the order of elements in the hash buckets. duke@435: zgu@3900: template void Hashtable::reverse(void* boundary) { duke@435: zgu@3900: for (int i = 0; i < this->table_size(); ++i) { zgu@3900: HashtableEntry* high_list = NULL; zgu@3900: HashtableEntry* low_list = NULL; zgu@3900: HashtableEntry* last_low_entry = NULL; zgu@3900: HashtableEntry* p = bucket(i); duke@435: while (p != NULL) { zgu@3900: HashtableEntry* next = p->next(); duke@435: if ((void*)p->literal() >= boundary) { duke@435: p->set_next(high_list); duke@435: high_list = p; duke@435: } else { duke@435: p->set_next(low_list); duke@435: low_list = p; duke@435: if (last_low_entry == NULL) { duke@435: last_low_entry = p; duke@435: } duke@435: } duke@435: p = next; duke@435: } duke@435: if (low_list != NULL) { duke@435: *bucket_addr(i) = low_list; duke@435: last_low_entry->set_next(high_list); duke@435: } else { duke@435: *bucket_addr(i) = high_list; duke@435: } duke@435: } duke@435: } duke@435: mgerdin@7207: template int RehashableHashtable::literal_size(Symbol *symbol) { iklam@5144: return symbol->size() * HeapWordSize; iklam@5144: } iklam@5144: mgerdin@7207: template int RehashableHashtable::literal_size(oop oop) { iklam@5144: // NOTE: this would over-count if (pre-JDK8) java_lang_Class::has_offset_field() is true, iklam@5144: // and the String.value array is shared by several Strings. However, starting from JDK8, iklam@5144: // the String.value array is not shared anymore. iklam@5144: assert(oop != NULL && oop->klass() == SystemDictionary::String_klass(), "only strings are supported"); iklam@5144: return (oop->size() + java_lang_String::value(oop)->size()) * HeapWordSize; iklam@5144: } iklam@5144: iklam@5144: // Dump footprint and bucket length statistics iklam@5144: // iklam@5144: // Note: if you create a new subclass of Hashtable, you will need to iklam@5144: // add a new function Hashtable::literal_size(MyNewType lit) iklam@5144: mgerdin@7207: template void RehashableHashtable::dump_table(outputStream* st, const char *table_name) { iklam@5144: NumberSeq summary; iklam@5144: int literal_bytes = 0; iklam@5144: for (int i = 0; i < this->table_size(); ++i) { iklam@5144: int count = 0; mgerdin@7207: for (HashtableEntry* e = this->bucket(i); iklam@5144: e != NULL; e = e->next()) { iklam@5144: count++; iklam@5144: literal_bytes += literal_size(e->literal()); iklam@5144: } iklam@5144: summary.add((double)count); iklam@5144: } iklam@5144: double num_buckets = summary.num(); iklam@5144: double num_entries = summary.sum(); iklam@5144: mgerdin@7207: int bucket_bytes = (int)num_buckets * sizeof(HashtableBucket); iklam@5144: int entry_bytes = (int)num_entries * sizeof(HashtableEntry); iklam@5144: int total_bytes = literal_bytes + bucket_bytes + entry_bytes; iklam@5144: iklam@5144: double bucket_avg = (num_buckets <= 0) ? 0 : (bucket_bytes / num_buckets); iklam@5144: double entry_avg = (num_entries <= 0) ? 0 : (entry_bytes / num_entries); iklam@5144: double literal_avg = (num_entries <= 0) ? 0 : (literal_bytes / num_entries); iklam@5144: iklam@5144: st->print_cr("%s statistics:", table_name); iklam@5144: st->print_cr("Number of buckets : %9d = %9d bytes, avg %7.3f", (int)num_buckets, bucket_bytes, bucket_avg); iklam@5144: st->print_cr("Number of entries : %9d = %9d bytes, avg %7.3f", (int)num_entries, entry_bytes, entry_avg); iklam@5144: st->print_cr("Number of literals : %9d = %9d bytes, avg %7.3f", (int)num_entries, literal_bytes, literal_avg); iklam@5144: st->print_cr("Total footprint : %9s = %9d bytes", "", total_bytes); iklam@5144: st->print_cr("Average bucket size : %9.3f", summary.avg()); iklam@5144: st->print_cr("Variance of bucket size : %9.3f", summary.variance()); iklam@5144: st->print_cr("Std. dev. of bucket size: %9.3f", summary.sd()); iklam@5144: st->print_cr("Maximum bucket size : %9d", (int)summary.maximum()); iklam@5144: } iklam@5144: duke@435: duke@435: // Dump the hash table buckets. duke@435: zgu@3900: template void BasicHashtable::copy_buckets(char** top, char* end) { zgu@3900: intptr_t len = _table_size * sizeof(HashtableBucket); duke@435: *(intptr_t*)(*top) = len; duke@435: *top += sizeof(intptr_t); duke@435: duke@435: *(intptr_t*)(*top) = _number_of_entries; duke@435: *top += sizeof(intptr_t); duke@435: duke@435: if (*top + len > end) { coleenp@2497: report_out_of_shared_space(SharedMiscData); duke@435: } zgu@3900: _buckets = (HashtableBucket*)memcpy(*top, _buckets, len); duke@435: *top += len; duke@435: } duke@435: duke@435: duke@435: #ifndef PRODUCT duke@435: zgu@3900: template void Hashtable::print() { duke@435: ResourceMark rm; duke@435: zgu@3900: for (int i = 0; i < BasicHashtable::table_size(); i++) { zgu@3900: HashtableEntry* entry = bucket(i); duke@435: while(entry != NULL) { duke@435: tty->print("%d : ", i); duke@435: entry->literal()->print(); duke@435: tty->cr(); duke@435: entry = entry->next(); duke@435: } duke@435: } duke@435: } duke@435: duke@435: zgu@3900: template void BasicHashtable::verify() { duke@435: int count = 0; duke@435: for (int i = 0; i < table_size(); i++) { zgu@3900: for (BasicHashtableEntry* p = bucket(i); p != NULL; p = p->next()) { duke@435: ++count; duke@435: } duke@435: } duke@435: assert(count == number_of_entries(), "number of hashtable entries incorrect"); duke@435: } duke@435: duke@435: duke@435: #endif // PRODUCT duke@435: duke@435: duke@435: #ifdef ASSERT duke@435: zgu@3900: template void BasicHashtable::verify_lookup_length(double load) { duke@435: if ((double)_lookup_length / (double)_lookup_count > load * 2.0) { duke@435: warning("Performance bug: SystemDictionary lookup_count=%d " duke@435: "lookup_length=%d average=%lf load=%f", duke@435: _lookup_count, _lookup_length, duke@435: (double) _lookup_length / _lookup_count, load); duke@435: } duke@435: } duke@435: duke@435: #endif coleenp@2497: // Explicitly instantiate these types mgerdin@7208: #if INCLUDE_ALL_GCS mgerdin@7208: template class Hashtable; mgerdin@7208: template class HashtableEntry; mgerdin@7208: template class BasicHashtable; mgerdin@7208: #endif coleenp@4037: template class Hashtable; mgerdin@7207: template class RehashableHashtable; mgerdin@7207: template class RehashableHashtable; zgu@3900: template class Hashtable; coleenp@4037: template class Hashtable; zgu@3900: template class Hashtable; hseigel@5784: #if defined(SOLARIS) || defined(CHECK_UNHANDLED_OOPS) zgu@3900: template class Hashtable; mgerdin@7207: template class RehashableHashtable; hseigel@5784: #endif // SOLARIS || CHECK_UNHANDLED_OOPS zgu@3900: template class Hashtable; zgu@3900: template class Hashtable; zgu@3900: template class HashtableEntry; zgu@3900: template class HashtableEntry; zgu@3900: template class HashtableEntry; zgu@3900: template class BasicHashtableEntry; zgu@3900: template class BasicHashtableEntry; zgu@3900: template class BasicHashtable; zgu@3900: template class BasicHashtable; zgu@3900: template class BasicHashtable; zgu@3900: template class BasicHashtable;