vmkit/mmtk/java/src/org/mmtk/plan/nogc/NoGCMutator.java

/*
 *  This file is part of the Jikes RVM project (http://jikesrvm.org).
 *
 *  This file is licensed to You under the Eclipse Public License (EPL);
 *  You may not use this file except in compliance with the License. You
 *  may obtain a copy of the License at
 *
 *      http://www.opensource.org/licenses/eclipse-1.0.php
 *
 *  See the COPYRIGHT.txt file distributed with this work for information
 *  regarding copyright ownership.
 */
package org.mmtk.plan.nogc;

import org.mmtk.plan.MutatorContext;
import org.mmtk.policy.ImmortalLocal;
import org.mmtk.policy.Space;
import org.mmtk.utility.alloc.Allocator;
import org.mmtk.vm.VM;

import org.vmmagic.pragma.*;
import org.vmmagic.unboxed.*;

/**
 * This class implements <i>per-mutator thread</i> behavior and state
 * for the <i>NoGC</i> plan, which simply allocates (without ever collecting
 * until the available space is exhausted.<p>
 *
 * Specifically, this class defines <i>NoGC</i> mutator-time allocation
 * through a bump pointer (<code>def</code>) and includes stubs for
 * per-mutator thread collection semantics (since there is no collection
 * in this plan, these remain just stubs).
 *
 * @see NoGC
 * @see NoGCCollector
 * @see org.mmtk.plan.StopTheWorldMutator
 * @see org.mmtk.plan.MutatorContext
 */
@Uninterruptible
public class NoGCMutator extends MutatorContext {

  /************************************************************************
   * Instance fields
   */
  private final ImmortalLocal nogc = new ImmortalLocal(NoGC.noGCSpace);


  /****************************************************************************
   * Mutator-time allocation
   */

  /**
   * Allocate memory for an object.
   *
   * @param bytes The number of bytes required for the object.
   * @param align Required alignment for the object.
   * @param offset Offset associated with the alignment.
   * @param allocator The allocator associated with this request.
   * @param site Allocation site
   * @return The address of the newly allocated memory.
   */
  @Inline
  @Override
  public Address alloc(int bytes, int align, int offset, int allocator, int site) {
    if (allocator == NoGC.ALLOC_DEFAULT) {
      return nogc.alloc(bytes, align, offset);
    }
    return super.alloc(bytes, align, offset, allocator, site);
  }

  /**
   * Perform post-allocation actions.  For many allocators none are
   * required.
   *
   * @param ref The newly allocated object
   * @param typeRef the type reference for the instance being created
   * @param bytes The size of the space to be allocated (in bytes)
   * @param allocator The allocator number to be used for this allocation
   */
  @Inline
  @Override
  public void postAlloc(ObjectReference ref, ObjectReference typeRef,
      int bytes, int allocator) {
    if (allocator != NoGC.ALLOC_DEFAULT) {
      super.postAlloc(ref, typeRef, bytes, allocator);
    }
  }

  /**
   * Return the allocator instance associated with a space
   * <code>space</code>, for this plan instance.
   *
   * @param space The space for which the allocator instance is desired.
   * @return The allocator instance associated with this plan instance
   * which is allocating into <code>space</code>, or <code>null</code>
   * if no appropriate allocator can be established.
   */
  @Override
  public Allocator getAllocatorFromSpace(Space space) {
    if (space == NoGC.noGCSpace) return nogc;
    return super.getAllocatorFromSpace(space);
  }


  /****************************************************************************
   * Collection
   */

  /**
   * Perform a per-mutator collection phase.
   *
   * @param phaseId The collection phase to perform
   * @param primary perform any single-threaded local activities.
   */
  @Inline
  @Override
  public final void collectionPhase(short phaseId, boolean primary) {
    VM.assertions.fail("GC Triggered in NoGC Plan.");
    /*
     if (phaseId == NoGC.PREPARE) {
     }

     if (phaseId == NoGC.RELEASE) {
     }
     super.collectionPhase(phaseId, primary);
     */
  }
}