duke@435: /*
xdono@905:  * Copyright 2003-2008 Sun Microsystems, Inc.  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:  *
duke@435:  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
duke@435:  * CA 95054 USA or visit www.sun.com if you need additional information or
duke@435:  * have any questions.
duke@435:  *
duke@435:  */
duke@435: 
duke@435: # include "incls/_precompiled.incl"
duke@435: # include "incls/_hashtable.cpp.incl"
duke@435: 
duke@435: HS_DTRACE_PROBE_DECL4(hs_private, hashtable__new_entry,
duke@435:   void*, unsigned int, oop, void*);
duke@435: 
duke@435: // This is a generic hashtable, designed to be used for the symbol
duke@435: // and string tables.
duke@435: //
duke@435: // It is implemented as an open hash table with a fixed number of buckets.
duke@435: //
duke@435: // %note:
duke@435: //  - HashtableEntrys are allocated in blocks to reduce the space overhead.
duke@435: 
duke@435: BasicHashtableEntry* BasicHashtable::new_entry(unsigned int hashValue) {
duke@435:   BasicHashtableEntry* entry;
duke@435: 
duke@435:   if (_free_list) {
duke@435:     entry = _free_list;
duke@435:     _free_list = _free_list->next();
duke@435:   } else {
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, "");
duke@435:       _first_free_entry = NEW_C_HEAP_ARRAY(char, len);
duke@435:       _end_block = _first_free_entry + len;
duke@435:     }
duke@435:     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: 
duke@435: HashtableEntry* Hashtable::new_entry(unsigned int hashValue, oop obj) {
duke@435:   HashtableEntry* entry;
duke@435: 
duke@435:   entry = (HashtableEntry*)BasicHashtable::new_entry(hashValue);
duke@435:   entry->set_literal(obj);   // clears literal string field
duke@435:   HS_DTRACE_PROBE4(hs_private, hashtable__new_entry,
duke@435:     this, hashValue, obj, entry);
duke@435:   return entry;
duke@435: }
duke@435: 
duke@435: 
duke@435: // GC support
duke@435: 
duke@435: void Hashtable::unlink(BoolObjectClosure* is_alive) {
duke@435:   // Readers of the table are unlocked, so we should only be removing
duke@435:   // entries at a safepoint.
duke@435:   assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
duke@435:   for (int i = 0; i < table_size(); ++i) {
duke@435:     for (HashtableEntry** p = bucket_addr(i); *p != NULL; ) {
duke@435:       HashtableEntry* entry = *p;
duke@435:       if (entry->is_shared()) {
duke@435:         break;
duke@435:       }
duke@435:       assert(entry->literal() != NULL, "just checking");
duke@435:       if (is_alive->do_object_b(entry->literal())) {
duke@435:         p = entry->next_addr();
duke@435:       } else {
duke@435:         *p = entry->next();
duke@435:         free_entry(entry);
duke@435:       }
duke@435:     }
duke@435:   }
duke@435: }
duke@435: 
duke@435: 
duke@435: void Hashtable::oops_do(OopClosure* f) {
duke@435:   for (int i = 0; i < table_size(); ++i) {
duke@435:     HashtableEntry** p = bucket_addr(i);
duke@435:     HashtableEntry* entry = bucket(i);
duke@435:     while (entry != NULL) {
duke@435:       f->do_oop(entry->literal_addr());
duke@435: 
duke@435:       // Did the closure remove the literal from the table?
duke@435:       if (entry->literal() == NULL) {
duke@435:         assert(!entry->is_shared(), "immutable hashtable entry?");
duke@435:         *p = entry->next();
duke@435:         free_entry(entry);
duke@435:       } else {
duke@435:         p = entry->next_addr();
duke@435:       }
duke@435:       entry = (HashtableEntry*)HashtableEntry::make_ptr(*p);
duke@435:     }
duke@435:   }
duke@435: }
duke@435: 
duke@435: 
duke@435: // Reverse the order of elements in the hash buckets.
duke@435: 
duke@435: void BasicHashtable::reverse() {
duke@435: 
duke@435:   for (int i = 0; i < _table_size; ++i) {
duke@435:     BasicHashtableEntry* new_list = NULL;
duke@435:     BasicHashtableEntry* p = bucket(i);
duke@435:     while (p != NULL) {
duke@435:       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: 
duke@435: 
duke@435: // Copy the table to the shared space.
duke@435: 
duke@435: 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) {
duke@435:     for (BasicHashtableEntry** p = _buckets[i].entry_addr();
duke@435:                               *p != NULL;
duke@435:                                p = (*p)->next_addr()) {
duke@435:       if (*top + entry_size() > end) {
duke@435:         warning("\nThe shared miscellaneous data space is not large "
duke@435:                 "enough to \npreload requested classes.  Use "
duke@435:                 "-XX:SharedMiscDataSize= to increase \nthe initial "
duke@435:                 "size of the miscellaneous data space.\n");
duke@435:         exit(2);
duke@435:       }
duke@435:       *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) {
duke@435:     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: 
duke@435: void Hashtable::reverse(void* boundary) {
duke@435: 
duke@435:   for (int i = 0; i < table_size(); ++i) {
duke@435:     HashtableEntry* high_list = NULL;
duke@435:     HashtableEntry* low_list = NULL;
duke@435:     HashtableEntry* last_low_entry = NULL;
duke@435:     HashtableEntry* p = bucket(i);
duke@435:     while (p != NULL) {
duke@435:       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: 
duke@435: 
duke@435: // Dump the hash table buckets.
duke@435: 
duke@435: void BasicHashtable::copy_buckets(char** top, char* end) {
duke@435:   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) {
duke@435:     warning("\nThe shared miscellaneous data space is not large "
duke@435:             "enough to \npreload requested classes.  Use "
duke@435:             "-XX:SharedMiscDataSize= to increase \nthe initial "
duke@435:             "size of the miscellaneous data space.\n");
duke@435:     exit(2);
duke@435:   }
duke@435:   _buckets = (HashtableBucket*)memcpy(*top, _buckets, len);
duke@435:   *top += len;
duke@435: }
duke@435: 
duke@435: 
duke@435: #ifndef PRODUCT
duke@435: 
duke@435: void Hashtable::print() {
duke@435:   ResourceMark rm;
duke@435: 
duke@435:   for (int i = 0; i < table_size(); i++) {
duke@435:     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: 
duke@435: void BasicHashtable::verify() {
duke@435:   int count = 0;
duke@435:   for (int i = 0; i < table_size(); i++) {
duke@435:     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: 
duke@435: 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