Quellcode-Bibliothek

^© Kompilation durch diese Firma

[Weder Korrektheit noch Funktionsfähigkeit der Software werden zugesichert.]

Datei: hashtable.cpp Sprache: C

/*
* Copyright (c) 2003, 2022, 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/dictionary.hpp"
#include "classfile/javaClasses.inline.hpp"
#include "classfile/vmClasses.hpp"
#include "code/nmethod.hpp"
#include "logging/log.hpp"
#include "memory/allocation.inline.hpp"
#include "memory/resourceArea.hpp"
#include "oops/oop.inline.hpp"
#include "oops/symbol.hpp"
#include "oops/weakHandle.inline.hpp"
#include "prims/jvmtiTagMapTable.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.

// Hashtable entry allocates in the C heap directly.

template <MEMFLAGS F> BasicHashtableEntry<F>* BasicHashtable<F>::new_entry(unsigned int hashValue) {
  BasicHashtableEntry<F>* entry = ::new (NEW_C_HEAP_ARRAY(char, this->entry_size(), F))
                                        BasicHashtableEntry<F>(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 = ::new (NEW_C_HEAP_ARRAY(char, this->entry_size(), F))
                                      HashtableEntry<T, F>(hashValue, obj);
  return entry;
}

template <MEMFLAGS F> inline void BasicHashtable<F>::free_entry(BasicHashtableEntry<F>* entry) {
  // Unlink from the Hashtable prior to freeing
  unlink_entry(entry);
  FREE_C_HEAP_ARRAY(char, entry);
  JFR_ONLY(_stats_rate.remove();)
}

template <MEMFLAGS F> void BasicHashtable<F>::free_buckets() {
  FREE_C_HEAP_ARRAY(HashtableBucket, _buckets);
  _buckets = NULL;
}

// Default overload, for types that are uninteresting.
template<typename T> static size_t literal_size(T) { return 0; }

static size_t literal_size(oop obj) {
  if (obj == NULL) {
    return 0;
  }

  size_t word_size = obj->size();

  if (obj->klass() == vmClasses::String_klass()) {
    // This may overcount if String.value arrays are shared.
    word_size += java_lang_String::value(obj)->size();
  }

  return word_size * HeapWordSize;
}

static size_t literal_size(WeakHandle v) {
  return literal_size(v.peek());
}

const double _resize_factor    = 2.0;     // by how much we will resize using current number of entries
const int _small_table_sizes[] = { 107, 1009, 2017, 4049, 5051, 10103, 20201, 40423 } ;
const int _small_array_size = sizeof(_small_table_sizes)/sizeof(int);

// possible hashmap sizes - odd primes that roughly double in size.
// To avoid excessive resizing the odd primes from 4801-76831 and
// 76831-307261 have been removed.
const int _large_table_sizes[] =  { 4801, 76831, 307261, 614563, 1228891,
    2457733, 4915219, 9830479, 19660831, 39321619, 78643219 };
const int _large_array_size = sizeof(_large_table_sizes)/sizeof(int);

// Calculate next "good" hashtable size based on requested count
template <MEMFLAGS F> int BasicHashtable<F>::calculate_resize(bool use_large_table_sizes) const {
  int requested = (int)(_resize_factor*number_of_entries());
  const int* primelist = use_large_table_sizes ? _large_table_sizes : _small_table_sizes;
  int arraysize =  use_large_table_sizes ? _large_array_size  : _small_array_size;
  int newsize;
  for (int i = 0; i < arraysize; i++) {
    newsize = primelist[i];
    if (newsize >= requested)
      break;
  }
  return newsize;
}

template <MEMFLAGS F> bool BasicHashtable<F>::resize(int new_size) {

  // Allocate new buckets
  HashtableBucket<F>* buckets_new = NEW_C_HEAP_ARRAY2_RETURN_NULL(HashtableBucket<F>, new_size, F, CURRENT_PC);
  if (buckets_new == NULL) {
    return false;
  }

  // Clear the new buckets
  for (int i = 0; i < new_size; i++) {
    buckets_new[i].clear();
  }

  int table_size_old = _table_size;
  // hash_to_index() uses _table_size, so switch the sizes now
  _table_size = new_size;

  // Move entries from the old table to a new table
  for (int index_old = 0; index_old < table_size_old; index_old++) {
    for (BasicHashtableEntry<F>* p = _buckets[index_old].get_entry(); p != NULL; ) {
      BasicHashtableEntry<F>* next = p->next();
      int index_new = hash_to_index(p->hash());

      p->set_next(buckets_new[index_new].get_entry());
      buckets_new[index_new].set_entry(p);
      p = next;
    }
  }

  // The old backets now can be released
  BasicHashtable<F>::free_buckets();

  // Switch to the new storage
  _buckets = buckets_new;

  return true;
}

template <MEMFLAGS F> bool BasicHashtable<F>::maybe_grow(int max_size, int load_factor) {
  assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");

  if (table_size() >= max_size) {
    return false;
  }
  if (number_of_entries() / table_size() > load_factor) {
    resize(MIN2<int>(table_size() * 2, max_size));
    return true;
  } else {
    return false;
  }
}

template <class T, MEMFLAGS F> TableStatistics Hashtable<T, F>::statistics_calculate(T (*literal_load_barrier)(HashtableEntry<T, F>*)) {
  NumberSeq summary;
  size_t 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++;
      T l = (literal_load_barrier != NULL) ? literal_load_barrier(e) : e->literal();
      literal_bytes += literal_size(l);
    }
    summary.add((double)count);
  }
  return TableStatistics(this->_stats_rate, summary, literal_bytes, sizeof(HashtableBucket<F>), sizeof(HashtableEntry<T, F>));
}

// Dump footprint and bucket length statistics
template <class T, MEMFLAGS F> void Hashtable<T, F>::print_table_statistics(outputStream* st,
                                                                            const char *table_name,
                                                                            T (*literal_load_barrier)(HashtableEntry<T, F>*)) {
  TableStatistics ts = statistics_calculate(literal_load_barrier);
  ts.print(st, table_name);
}

#ifndef PRODUCT
template <class T> static void print_literal(T const& l) { l.print(); }
template <class T> static void print_literal(T* l) { print_literal(*l); }

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);
      print_literal(entry->literal());
      tty->cr();
      entry = entry->next();
    }
  }
}

template <MEMFLAGS F>
template <class T> void BasicHashtable<F>::verify_table(const char* table_name) {
  int element_count = 0;
  int max_bucket_count = 0;
  int max_bucket_number = 0;
  for (int index = 0; index < table_size(); index++) {
    int bucket_count = 0;
    for (T* probe = (T*)bucket(index); probe != NULL; probe = probe->next()) {
      probe->verify();
      bucket_count++;
    }
    element_count += bucket_count;
    if (bucket_count > max_bucket_count) {
      max_bucket_count = bucket_count;
      max_bucket_number = index;
    }
  }
  guarantee(number_of_entries() == element_count,
            "Verify of %s failed", table_name);

  // Log some statistics about the hashtable
  log_info(hashtables)("%s max bucket size %d bucket %d element count %d table size %d", table_name,
                       max_bucket_count, max_bucket_number, _number_of_entries, _table_size);
  if (_number_of_entries > 0 && log_is_enabled(Debug, hashtables)) {
    for (int index = 0; index < table_size(); index++) {
      int bucket_count = 0;
      for (T* probe = (T*)bucket(index); probe != NULL; probe = probe->next()) {
        log_debug(hashtables)("bucket %d hash " INTPTR_FORMAT, index, (intptr_t)probe->hash());
        bucket_count++;
      }
      if (bucket_count > 0) {
        log_debug(hashtables)("bucket %d count %d", index, bucket_count);
      }
    }
  }
}
#endif // PRODUCT

// Explicitly instantiate these types
template class BasicHashtable<mtGC>;
template class BasicHashtable<mtServiceability>;

template class Hashtable<nmethod*, mtGC>;
template class Hashtable<WeakHandle, mtServiceability>;

¤ Dauer der Verarbeitung: 0.15 Sekunden (vorverarbeitet) ¤

Download des Quellennavigators
Download des sprechenden Kalenders
in der Quellcodebibliothek suchen

Haftungshinweis

Die Informationen auf dieser Webseite wurden nach bestem Wissen sorgfältig zusammengestellt. Es wird jedoch weder Vollständigkeit, noch Richtigkeit, noch Qualität der bereit gestellten Informationen zugesichert.

Bemerkung:

Die farbliche Syntaxdarstellung ist noch experimentell.