/*

 * 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.

 *

 *

 */

# 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