jdk8-mips64-public/hotspot: src/share/vm/utilities/hashtable.cpp@c96030fff130 (annotated)

src/share/vm/utilities/hashtable.cpp@c96030fff130 (annotated)

src/share/vm/utilities/hashtable.cpp

Thu, 20 Nov 2008 16:56:09 -0800

author: ysr
date: Thu, 20 Nov 2008 16:56:09 -0800
changeset 888: c96030fff130
parent 867: 275a3b7ff0d6
child 905: ad8c8ca4ab0f
permissions: -rw-r--r--

6684579: SoftReference processing can be made more efficient
Summary: For current soft-ref clearing policies, we can decide at marking time if a soft-reference will definitely not be cleared, postponing the decision of whether it will definitely be cleared to the final reference processing phase. This can be especially beneficial in the case of concurrent collectors where the marking is usually concurrent but reference processing is usually not.
Reviewed-by: jmasa

 /*
  * Copyright 2003-2005 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/_hashtable.cpp.incl"
 HS_DTRACE_PROBE_DECL4(hs_private, hashtable__new_entry,
   void*, unsigned int, oop, void*);
 // This is a generic hashtable, designed to be used for the symbol
 // and string tables.
 //
 // It is implemented as an open hash table with a fixed number of buckets.
 //
 // %note:
 //  - HashtableEntrys are allocated in blocks to reduce the space overhead.
 BasicHashtableEntry* BasicHashtable::new_entry(unsigned int hashValue) {
   BasicHashtableEntry* entry;
   if (_free_list) {
     entry = _free_list;
     _free_list = _free_list->next();
   } else {
     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_ARRAY(char, len);
       _end_block = _first_free_entry + len;
     }
     entry = (BasicHashtableEntry*)_first_free_entry;
     _first_free_entry += _entry_size;
   }
   assert(_entry_size % HeapWordSize == 0, "");
   entry->set_hash(hashValue);
   return entry;
 }
 HashtableEntry* Hashtable::new_entry(unsigned int hashValue, oop obj) {
   HashtableEntry* entry;
   entry = (HashtableEntry*)BasicHashtable::new_entry(hashValue);
   entry->set_literal(obj);   // clears literal string field
   HS_DTRACE_PROBE4(hs_private, hashtable__new_entry,
     this, hashValue, obj, entry);
   return entry;
 }
 // GC support
 void Hashtable::unlink(BoolObjectClosure* is_alive) {
   // Readers of the table are unlocked, so we should only be removing
   // entries at a safepoint.
   assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
   for (int i = 0; i < table_size(); ++i) {
     for (HashtableEntry** p = bucket_addr(i); *p != NULL; ) {
       HashtableEntry* entry = *p;
       if (entry->is_shared()) {
         break;
       }
       assert(entry->literal() != NULL, "just checking");
       if (is_alive->do_object_b(entry->literal())) {
         p = entry->next_addr();
       } else {
         *p = entry->next();
         free_entry(entry);
       }
     }
   }
 }
 void Hashtable::oops_do(OopClosure* f) {
   for (int i = 0; i < table_size(); ++i) {
     HashtableEntry** p = bucket_addr(i);
     HashtableEntry* entry = bucket(i);
     while (entry != NULL) {
       f->do_oop(entry->literal_addr());
       // Did the closure remove the literal from the table?
       if (entry->literal() == NULL) {
         assert(!entry->is_shared(), "immutable hashtable entry?");
         *p = entry->next();
         free_entry(entry);
       } else {
         p = entry->next_addr();
       }
       entry = (HashtableEntry*)HashtableEntry::make_ptr(*p);
     }
   }
 }
 // Reverse the order of elements in the hash buckets.
 void BasicHashtable::reverse() {
   for (int i = 0; i < _table_size; ++i) {
     BasicHashtableEntry* new_list = NULL;
     BasicHashtableEntry* p = bucket(i);
     while (p != NULL) {
       BasicHashtableEntry* 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.
 void BasicHashtable::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** p = _buckets[i].entry_addr();
                               *p != NULL;
                                p = (*p)->next_addr()) {
       if (*top + entry_size() > end) {
         warning("\nThe shared miscellaneous data space is not large "
                 "enough to \npreload requested classes.  Use "
                 "-XX:SharedMiscDataSize= to increase \nthe initial "
                 "size of the miscellaneous data space.\n");
         exit(2);
       }
       *p = (BasicHashtableEntry*)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* p = bucket(i); p != NULL; p = p->next()) {
       p->set_shared();
     }
   }
 }
 // Reverse the order of elements in the hash buckets.
 void Hashtable::reverse(void* boundary) {
   for (int i = 0; i < table_size(); ++i) {
     HashtableEntry* high_list = NULL;
     HashtableEntry* low_list = NULL;
     HashtableEntry* last_low_entry = NULL;
     HashtableEntry* p = bucket(i);
     while (p != NULL) {
       HashtableEntry* 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;
     }
   }
 }
 // Dump the hash table buckets.
 void BasicHashtable::copy_buckets(char** top, char* end) {
   intptr_t len = _table_size * sizeof(HashtableBucket);
   *(intptr_t*)(*top) = len;
   *top += sizeof(intptr_t);
   *(intptr_t*)(*top) = _number_of_entries;
   *top += sizeof(intptr_t);
   if (*top + len > end) {
     warning("\nThe shared miscellaneous data space is not large "
             "enough to \npreload requested classes.  Use "
             "-XX:SharedMiscDataSize= to increase \nthe initial "
             "size of the miscellaneous data space.\n");
     exit(2);
   }
   _buckets = (HashtableBucket*)memcpy(*top, _buckets, len);
   *top += len;
 }
 #ifndef PRODUCT
 void Hashtable::print() {
   ResourceMark rm;
   for (int i = 0; i < table_size(); i++) {
     HashtableEntry* entry = bucket(i);
     while(entry != NULL) {
       tty->print("%d : ", i);
       entry->literal()->print();
       tty->cr();
       entry = entry->next();
     }
   }
 }
 void BasicHashtable::verify() {
   int count = 0;
   for (int i = 0; i < table_size(); i++) {
     for (BasicHashtableEntry* p = bucket(i); p != NULL; p = p->next()) {
       ++count;
     }
   }
   assert(count == number_of_entries(), "number of hashtable entries incorrect");
 }
 #endif // PRODUCT
 #ifdef ASSERT
 void BasicHashtable::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

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/utilities/hashtable.cpp@c96030fff130 (annotated)

src/share/vm/utilities/hashtable.cpp