| /* |
| * Copyright (c) 2003, 2014, 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/javaClasses.hpp" |
| #include "classfile/stringTable.hpp" |
| #include "memory/allocation.inline.hpp" |
| #include "memory/filemap.hpp" |
| #include "memory/resourceArea.hpp" |
| #include "oops/oop.inline.hpp" |
| #include "runtime/safepoint.hpp" |
| #include "utilities/dtrace.hpp" |
| #include "utilities/hashtable.hpp" |
| #include "utilities/hashtable.inline.hpp" |
| #include "utilities/numberSeq.hpp" |
| |
| |
| // This hashtable is implemented as an open hash table with a fixed number of buckets. |
| |
| template <MEMFLAGS F> BasicHashtableEntry<F>* BasicHashtable<F>::new_entry_free_list() { |
| BasicHashtableEntry<F>* entry = NULL; |
| if (_free_list != NULL) { |
| entry = _free_list; |
| _free_list = _free_list->next(); |
| } |
| return entry; |
| } |
| |
| // HashtableEntrys are allocated in blocks to reduce the space overhead. |
| template <MEMFLAGS F> BasicHashtableEntry<F>* BasicHashtable<F>::new_entry(unsigned int hashValue) { |
| BasicHashtableEntry<F>* entry = new_entry_free_list(); |
| |
| if (entry == NULL) { |
| if (_first_free_entry + _entry_size >= _end_block) { |
| int block_size = MIN2(512, MAX2((int)_table_size / 2, (int)_number_of_entries)); |
| int len = _entry_size * block_size; |
| len = 1 << log2_intptr(len); // round down to power of 2 |
| assert(len >= _entry_size, ""); |
| _first_free_entry = NEW_C_HEAP_ARRAY2(char, len, F, CURRENT_PC); |
| _end_block = _first_free_entry + len; |
| } |
| entry = (BasicHashtableEntry<F>*)_first_free_entry; |
| _first_free_entry += _entry_size; |
| } |
| |
| assert(_entry_size % HeapWordSize == 0, ""); |
| entry->set_hash(hashValue); |
| return entry; |
| } |
| |
| |
| template <class T, MEMFLAGS F> HashtableEntry<T, F>* Hashtable<T, F>::new_entry(unsigned int hashValue, T obj) { |
| HashtableEntry<T, F>* entry; |
| |
| entry = (HashtableEntry<T, F>*)BasicHashtable<F>::new_entry(hashValue); |
| entry->set_literal(obj); |
| return entry; |
| } |
| |
| // Check to see if the hashtable is unbalanced. The caller set a flag to |
| // rehash at the next safepoint. If this bucket is 60 times greater than the |
| // expected average bucket length, it's an unbalanced hashtable. |
| // This is somewhat an arbitrary heuristic but if one bucket gets to |
| // rehash_count which is currently 100, there's probably something wrong. |
| |
| template <class T, MEMFLAGS F> bool RehashableHashtable<T, F>::check_rehash_table(int count) { |
| assert(this->table_size() != 0, "underflow"); |
| if (count > (((double)this->number_of_entries()/(double)this->table_size())*rehash_multiple)) { |
| // Set a flag for the next safepoint, which should be at some guaranteed |
| // safepoint interval. |
| return true; |
| } |
| return false; |
| } |
| |
| template <class T, MEMFLAGS F> juint RehashableHashtable<T, F>::_seed = 0; |
| |
| // Create a new table and using alternate hash code, populate the new table |
| // with the existing elements. This can be used to change the hash code |
| // and could in the future change the size of the table. |
| |
| template <class T, MEMFLAGS F> void RehashableHashtable<T, F>::move_to(RehashableHashtable<T, F>* new_table) { |
| |
| // Initialize the global seed for hashing. |
| _seed = AltHashing::compute_seed(); |
| assert(seed() != 0, "shouldn't be zero"); |
| |
| int saved_entry_count = this->number_of_entries(); |
| |
| // Iterate through the table and create a new entry for the new table |
| for (int i = 0; i < new_table->table_size(); ++i) { |
| for (HashtableEntry<T, F>* p = this->bucket(i); p != NULL; ) { |
| HashtableEntry<T, F>* next = p->next(); |
| T string = p->literal(); |
| // Use alternate hashing algorithm on the symbol in the first table |
| unsigned int hashValue = string->new_hash(seed()); |
| // Get a new index relative to the new table (can also change size) |
| int index = new_table->hash_to_index(hashValue); |
| p->set_hash(hashValue); |
| // Keep the shared bit in the Hashtable entry to indicate that this entry |
| // can't be deleted. The shared bit is the LSB in the _next field so |
| // walking the hashtable past these entries requires |
| // BasicHashtableEntry::make_ptr() call. |
| bool keep_shared = p->is_shared(); |
| this->unlink_entry(p); |
| new_table->add_entry(index, p); |
| if (keep_shared) { |
| p->set_shared(); |
| } |
| p = next; |
| } |
| } |
| // give the new table the free list as well |
| new_table->copy_freelist(this); |
| assert(new_table->number_of_entries() == saved_entry_count, "lost entry on dictionary copy?"); |
| |
| // Destroy memory used by the buckets in the hashtable. The memory |
| // for the elements has been used in a new table and is not |
| // destroyed. The memory reuse will benefit resizing the SystemDictionary |
| // to avoid a memory allocation spike at safepoint. |
| BasicHashtable<F>::free_buckets(); |
| } |
| |
| template <MEMFLAGS F> void BasicHashtable<F>::free_buckets() { |
| if (NULL != _buckets) { |
| // Don't delete the buckets in the shared space. They aren't |
| // allocated by os::malloc |
| if (!UseSharedSpaces || |
| !FileMapInfo::current_info()->is_in_shared_space(_buckets)) { |
| FREE_C_HEAP_ARRAY(HashtableBucket, _buckets, F); |
| } |
| _buckets = NULL; |
| } |
| } |
| |
| |
| // Reverse the order of elements in the hash buckets. |
| |
| template <MEMFLAGS F> void BasicHashtable<F>::reverse() { |
| |
| for (int i = 0; i < _table_size; ++i) { |
| BasicHashtableEntry<F>* new_list = NULL; |
| BasicHashtableEntry<F>* p = bucket(i); |
| while (p != NULL) { |
| BasicHashtableEntry<F>* next = p->next(); |
| p->set_next(new_list); |
| new_list = p; |
| p = next; |
| } |
| *bucket_addr(i) = new_list; |
| } |
| } |
| |
| |
| // Copy the table to the shared space. |
| |
| template <MEMFLAGS F> void BasicHashtable<F>::copy_table(char** top, char* end) { |
| |
| // Dump the hash table entries. |
| |
| intptr_t *plen = (intptr_t*)(*top); |
| *top += sizeof(*plen); |
| |
| int i; |
| for (i = 0; i < _table_size; ++i) { |
| for (BasicHashtableEntry<F>** p = _buckets[i].entry_addr(); |
| *p != NULL; |
| p = (*p)->next_addr()) { |
| if (*top + entry_size() > end) { |
| report_out_of_shared_space(SharedMiscData); |
| } |
| *p = (BasicHashtableEntry<F>*)memcpy(*top, *p, entry_size()); |
| *top += entry_size(); |
| } |
| } |
| *plen = (char*)(*top) - (char*)plen - sizeof(*plen); |
| |
| // Set the shared bit. |
| |
| for (i = 0; i < _table_size; ++i) { |
| for (BasicHashtableEntry<F>* p = bucket(i); p != NULL; p = p->next()) { |
| p->set_shared(); |
| } |
| } |
| } |
| |
| |
| |
| // Reverse the order of elements in the hash buckets. |
| |
| template <class T, MEMFLAGS F> void Hashtable<T, F>::reverse(void* boundary) { |
| |
| for (int i = 0; i < this->table_size(); ++i) { |
| HashtableEntry<T, F>* high_list = NULL; |
| HashtableEntry<T, F>* low_list = NULL; |
| HashtableEntry<T, F>* last_low_entry = NULL; |
| HashtableEntry<T, F>* p = bucket(i); |
| while (p != NULL) { |
| HashtableEntry<T, F>* next = p->next(); |
| if ((void*)p->literal() >= boundary) { |
| p->set_next(high_list); |
| high_list = p; |
| } else { |
| p->set_next(low_list); |
| low_list = p; |
| if (last_low_entry == NULL) { |
| last_low_entry = p; |
| } |
| } |
| p = next; |
| } |
| if (low_list != NULL) { |
| *bucket_addr(i) = low_list; |
| last_low_entry->set_next(high_list); |
| } else { |
| *bucket_addr(i) = high_list; |
| } |
| } |
| } |
| |
| template <class T, MEMFLAGS F> int RehashableHashtable<T, F>::literal_size(Symbol *symbol) { |
| return symbol->size() * HeapWordSize; |
| } |
| |
| template <class T, MEMFLAGS F> int RehashableHashtable<T, F>::literal_size(oop oop) { |
| // NOTE: this would over-count if (pre-JDK8) java_lang_Class::has_offset_field() is true, |
| // and the String.value array is shared by several Strings. However, starting from JDK8, |
| // the String.value array is not shared anymore. |
| assert(oop != NULL && oop->klass() == SystemDictionary::String_klass(), "only strings are supported"); |
| return (oop->size() + java_lang_String::value(oop)->size()) * HeapWordSize; |
| } |
| |
| // Dump footprint and bucket length statistics |
| // |
| // Note: if you create a new subclass of Hashtable<MyNewType, F>, you will need to |
| // add a new function Hashtable<T, F>::literal_size(MyNewType lit) |
| |
| template <class T, MEMFLAGS F> void RehashableHashtable<T, F>::dump_table(outputStream* st, const char *table_name) { |
| NumberSeq summary; |
| int literal_bytes = 0; |
| for (int i = 0; i < this->table_size(); ++i) { |
| int count = 0; |
| for (HashtableEntry<T, F>* e = this->bucket(i); |
| e != NULL; e = e->next()) { |
| count++; |
| literal_bytes += literal_size(e->literal()); |
| } |
| summary.add((double)count); |
| } |
| double num_buckets = summary.num(); |
| double num_entries = summary.sum(); |
| |
| int bucket_bytes = (int)num_buckets * sizeof(HashtableBucket<F>); |
| int entry_bytes = (int)num_entries * sizeof(HashtableEntry<T, F>); |
| int total_bytes = literal_bytes + bucket_bytes + entry_bytes; |
| |
| double bucket_avg = (num_buckets <= 0) ? 0 : (bucket_bytes / num_buckets); |
| double entry_avg = (num_entries <= 0) ? 0 : (entry_bytes / num_entries); |
| double literal_avg = (num_entries <= 0) ? 0 : (literal_bytes / num_entries); |
| |
| st->print_cr("%s statistics:", table_name); |
| st->print_cr("Number of buckets : %9d = %9d bytes, avg %7.3f", (int)num_buckets, bucket_bytes, bucket_avg); |
| st->print_cr("Number of entries : %9d = %9d bytes, avg %7.3f", (int)num_entries, entry_bytes, entry_avg); |
| st->print_cr("Number of literals : %9d = %9d bytes, avg %7.3f", (int)num_entries, literal_bytes, literal_avg); |
| st->print_cr("Total footprint : %9s = %9d bytes", "", total_bytes); |
| st->print_cr("Average bucket size : %9.3f", summary.avg()); |
| st->print_cr("Variance of bucket size : %9.3f", summary.variance()); |
| st->print_cr("Std. dev. of bucket size: %9.3f", summary.sd()); |
| st->print_cr("Maximum bucket size : %9d", (int)summary.maximum()); |
| } |
| |
| |
| // Dump the hash table buckets. |
| |
| template <MEMFLAGS F> void BasicHashtable<F>::copy_buckets(char** top, char* end) { |
| intptr_t len = _table_size * sizeof(HashtableBucket<F>); |
| *(intptr_t*)(*top) = len; |
| *top += sizeof(intptr_t); |
| |
| *(intptr_t*)(*top) = _number_of_entries; |
| *top += sizeof(intptr_t); |
| |
| if (*top + len > end) { |
| report_out_of_shared_space(SharedMiscData); |
| } |
| _buckets = (HashtableBucket<F>*)memcpy(*top, _buckets, len); |
| *top += len; |
| } |
| |
| |
| #ifndef PRODUCT |
| |
| template <class T, MEMFLAGS F> void Hashtable<T, F>::print() { |
| ResourceMark rm; |
| |
| for (int i = 0; i < BasicHashtable<F>::table_size(); i++) { |
| HashtableEntry<T, F>* entry = bucket(i); |
| while(entry != NULL) { |
| tty->print("%d : ", i); |
| entry->literal()->print(); |
| tty->cr(); |
| entry = entry->next(); |
| } |
| } |
| } |
| |
| |
| template <MEMFLAGS F> void BasicHashtable<F>::verify() { |
| int count = 0; |
| for (int i = 0; i < table_size(); i++) { |
| for (BasicHashtableEntry<F>* p = bucket(i); p != NULL; p = p->next()) { |
| ++count; |
| } |
| } |
| assert(count == number_of_entries(), "number of hashtable entries incorrect"); |
| } |
| |
| |
| #endif // PRODUCT |
| |
| #ifdef ASSERT |
| |
| template <MEMFLAGS F> void BasicHashtable<F>::verify_lookup_length(double load) { |
| if ((double)_lookup_length / (double)_lookup_count > load * 2.0) { |
| warning("Performance bug: SystemDictionary lookup_count=%d " |
| "lookup_length=%d average=%lf load=%f", |
| _lookup_count, _lookup_length, |
| (double) _lookup_length / _lookup_count, load); |
| } |
| } |
| |
| #endif |
| |
| |
| // Explicitly instantiate these types |
| #if INCLUDE_ALL_GCS |
| template class Hashtable<nmethod*, mtGC>; |
| template class HashtableEntry<nmethod*, mtGC>; |
| template class BasicHashtable<mtGC>; |
| #endif |
| template class Hashtable<ConstantPool*, mtClass>; |
| template class RehashableHashtable<Symbol*, mtSymbol>; |
| template class RehashableHashtable<oopDesc*, mtSymbol>; |
| template class Hashtable<Symbol*, mtSymbol>; |
| template class Hashtable<Klass*, mtClass>; |
| template class Hashtable<oop, mtClass>; |
| #if defined(SOLARIS) || defined(CHECK_UNHANDLED_OOPS) |
| template class Hashtable<oop, mtSymbol>; |
| template class RehashableHashtable<oop, mtSymbol>; |
| #endif // SOLARIS || CHECK_UNHANDLED_OOPS |
| template class Hashtable<oopDesc*, mtSymbol>; |
| template class Hashtable<Symbol*, mtClass>; |
| template class HashtableEntry<Symbol*, mtSymbol>; |
| template class HashtableEntry<Symbol*, mtClass>; |
| template class HashtableEntry<oop, mtSymbol>; |
| template class BasicHashtableEntry<mtSymbol>; |
| template class BasicHashtableEntry<mtCode>; |
| template class BasicHashtable<mtClass>; |
| template class BasicHashtable<mtSymbol>; |
| template class BasicHashtable<mtCode>; |
| template class BasicHashtable<mtInternal>; |