/*

 * Copyright (c) 2017, 2018, 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/javaClasses.hpp"

#include "memory/allocation.hpp"

#include "memory/resourceArea.hpp"

#include "oops/access.inline.hpp"

#include "oops/oop.inline.hpp"

#include "oops/method.hpp"

#include "oops/symbol.hpp"

#include "prims/resolvedMethodTable.hpp"

#include "runtime/handles.inline.hpp"

#include "runtime/mutexLocker.hpp"

#include "runtime/safepointVerifiers.hpp"

#include "utilities/hashtable.inline.hpp"

#include "utilities/macros.hpp"

oop ResolvedMethodEntry::object() {

}

oop ResolvedMethodEntry::object_no_keepalive() {

  // The AS_NO_KEEPALIVE peeks at the oop without keeping it alive.

  // This is dangerous in general but is okay if the loaded oop does

  // not leak out past a thread transition where a safepoint can happen.

  // A subsequent oop_load without AS_NO_KEEPALIVE (the object() accessor)

  // keeps the oop alive before doing so.

}

ResolvedMethodTable::ResolvedMethodTable()

oop ResolvedMethodTable::lookup(int index, unsigned int hash, Method* method) {

  for (ResolvedMethodEntry* p = bucket(index); p != NULL; p = p->next()) {

    if (p->hash() == hash) {

      // Peek the object to check if it is the right target.

      oop target = p->object_no_keepalive();

      // The method is in the table as a target already

        ResourceMark rm;

        log_debug(membername, table) ("ResolvedMethod entry found for %s index %d",

                                       method->name_and_sig_as_C_string(), index);

        // The object() accessor makes sure the target object is kept alive before

        // leaking out.

        return p->object();

      }

    }

  }

  return NULL;

}

unsigned int ResolvedMethodTable::compute_hash(Method* method) {

  unsigned int name_hash = method->name()->identity_hash();

  unsigned int signature_hash = method->signature()->identity_hash();

  return name_hash ^ signature_hash;

}

oop ResolvedMethodTable::lookup(Method* method) {

  unsigned int hash = compute_hash(method);

  int index = hash_to_index(hash);

  return lookup(index, hash, method);

}

  assert_locked_or_safepoint(ResolvedMethodTable_lock);

  unsigned int hash = compute_hash(method);

  int index = hash_to_index(hash);

  // One was added while aquiring the lock

  oop entry = lookup(index, hash, method);

  if (entry != NULL) {

    return entry;

  }

  ResourceMark rm;

  log_debug(membername, table) ("ResolvedMethod entry added for %s index %d",

                                 method->name_and_sig_as_C_string(), index);

}

ResolvedMethodTable* ResolvedMethodTable::_the_table = NULL;

oop ResolvedMethodTable::find_method(Method* method) {

  oop entry = _the_table->lookup(method);

  return entry;

}

oop ResolvedMethodTable::add_method(Handle resolved_method_name) {

  MutexLocker ml(ResolvedMethodTable_lock);

  DEBUG_ONLY(NoSafepointVerifier nsv);

  // Check if method has been redefined while taking out ResolvedMethodTable_lock, if so

  // use new method.

  Method* method = (Method*)java_lang_invoke_ResolvedMethodName::vmtarget(resolved_method_name());

  assert(method->is_method(), "must be method");

  if (method->is_old()) {

    // Replace method with redefined version

    InstanceKlass* holder = method->method_holder();

    method = holder->method_with_idnum(method->method_idnum());

    java_lang_invoke_ResolvedMethodName::set_vmtarget(resolved_method_name(), method);

  }

  // Set flag in class to indicate this InstanceKlass has entries in the table

  // to avoid walking table during redefinition if none of the redefined classes

  // have any membernames in the table.

  method->method_holder()->set_has_resolved_methods();

}

// Removing entries

int ResolvedMethodTable::_oops_removed = 0;

int ResolvedMethodTable::_oops_counted = 0;

// Serially invoke removed unused oops from the table.

// This is done late during GC.

  _oops_removed = 0;

  _oops_counted = 0;

  for (int i = 0; i < _the_table->table_size(); ++i) {

    ResolvedMethodEntry** p = _the_table->bucket_addr(i);

    ResolvedMethodEntry* entry = _the_table->bucket(i);

    while (entry != NULL) {

      _oops_counted++;

        p = entry->next_addr();

      } else {

        _oops_removed++;

        if (log_is_enabled(Debug, membername, table)) {

        }

        *p = entry->next();

        _the_table->free_entry(entry);

      }

      // get next entry

    }

  }

  log_debug(membername, table) ("ResolvedMethod entries counted %d removed %d",

                                _oops_counted, _oops_removed);

}

#ifndef PRODUCT

void ResolvedMethodTable::print() {

  for (int i = 0; i < table_size(); ++i) {

    ResolvedMethodEntry* entry = bucket(i);

    while (entry != NULL) {

      tty->print("%d : ", i);

      oop rmethod_name = entry->object_no_keepalive();

      entry = entry->next();

    }

  }

}

#endif // PRODUCT

#if INCLUDE_JVMTI

// It is called at safepoint only for RedefineClasses

void ResolvedMethodTable::adjust_method_entries(bool * trace_name_printed) {

  assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");

  // For each entry in RMT, change to new method

  for (int i = 0; i < _the_table->table_size(); ++i) {

      oop mem_name = entry->object_no_keepalive();

      Method* old_method = (Method*)java_lang_invoke_ResolvedMethodName::vmtarget(mem_name);

      if (old_method->is_old()) {

        if (old_method->is_deleted()) {

          // leave deleted method in ResolvedMethod for now (this is a bug that we don't mark

          // these on_stack)

          continue;

        }

        InstanceKlass* holder = old_method->method_holder();

        Method* new_method = holder->method_with_idnum(old_method->orig_method_idnum());

        assert(holder == new_method->method_holder(), "call after swapping redefined guts");

        assert(new_method != NULL, "method_with_idnum() should not be NULL");

        assert(old_method != new_method, "sanity check");

        java_lang_invoke_ResolvedMethodName::set_vmtarget(mem_name, new_method);

        ResourceMark rm;

        if (!(*trace_name_printed)) {

          log_info(redefine, class, update)("adjust: name=%s", old_method->method_holder()->external_name());

           *trace_name_printed = true;

        }

        log_debug(redefine, class, update, constantpool)

          ("ResolvedMethod method update: %s(%s)",

           new_method->name()->as_C_string(), new_method->signature()->as_C_string());

      }

    }

  }

}

#endif // INCLUDE_JVMTI