/*

 * Copyright (c) 2000, 2019, 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.

 *

 */

//

// The ObjectHeap is an abstraction over all generations in the VM

// It gives access to all present objects and classes.

//

package sun.jvm.hotspot.oops;

import java.util.*;

import sun.jvm.hotspot.debugger.*;

import sun.jvm.hotspot.gc.cms.*;

import sun.jvm.hotspot.gc.shared.*;

import sun.jvm.hotspot.gc.epsilon.*;

import sun.jvm.hotspot.gc.g1.*;

import sun.jvm.hotspot.gc.shenandoah.*;

import sun.jvm.hotspot.gc.parallel.*;

import sun.jvm.hotspot.gc.z.*;

import sun.jvm.hotspot.memory.*;

import sun.jvm.hotspot.runtime.*;

import sun.jvm.hotspot.types.*;

import sun.jvm.hotspot.utilities.*;

public class ObjectHeap {

  private static final boolean DEBUG;

  static {

    DEBUG = System.getProperty("sun.jvm.hotspot.oops.ObjectHeap.DEBUG") != null;

  }

  public ObjectHeap(TypeDataBase db) throws WrongTypeException {

    // Get commonly used sizes of basic types

    oopSize     = VM.getVM().getOopSize();

    byteSize    = db.getJByteType().getSize();

    charSize    = db.getJCharType().getSize();

    booleanSize = db.getJBooleanType().getSize();

    intSize     = db.getJIntType().getSize();

    shortSize   = db.getJShortType().getSize();

    longSize    = db.getJLongType().getSize();

    floatSize   = db.getJFloatType().getSize();

    doubleSize  = db.getJDoubleType().getSize();

  }

  /** Comparison operation for oops, either or both of which may be null */

  public boolean equal(Oop o1, Oop o2) {

    if (o1 != null) return o1.equals(o2);

    return (o2 == null);

  }

  // Cached sizes of basic types

  private long oopSize;

  private long byteSize;

  private long charSize;

  private long booleanSize;

  private long intSize;

  private long shortSize;

  private long longSize;

  private long floatSize;

  private long doubleSize;

  public long getOopSize()     { return oopSize;     }

  public long getByteSize()    { return byteSize;    }

  public long getCharSize()    { return charSize;    }

  public long getBooleanSize() { return booleanSize; }

  public long getIntSize()     { return intSize;     }

  public long getShortSize()   { return shortSize;   }

  public long getLongSize()    { return longSize;    }

  public long getFloatSize()   { return floatSize;   }

  public long getDoubleSize()  { return doubleSize;  }

  /** an interface to filter objects while walking heap */

  public static interface ObjectFilter {

    public boolean canInclude(Oop obj);

  }

  /** The base heap iteration mechanism */

  public void iterate(HeapVisitor visitor) {

    iterateLiveRegions(collectLiveRegions(), visitor, null);

  }

  /** iterate objects satisfying a specified ObjectFilter */

  public void iterate(HeapVisitor visitor, ObjectFilter of) {

    iterateLiveRegions(collectLiveRegions(), visitor, of);

  }

  /** iterate objects of given Klass. param 'includeSubtypes' tells whether to

   *  include objects of subtypes or not */

  public void iterateObjectsOfKlass(HeapVisitor visitor, final Klass k, boolean includeSubtypes) {

    if (includeSubtypes) {

      if (k.isFinal()) {

        // do the simpler "exact" klass loop

        iterateExact(visitor, k);

      } else {

        iterateSubtypes(visitor, k);

      }

    } else {

      // there can no object of abstract classes and interfaces

      if (!k.isAbstract() && !k.isInterface()) {

        iterateExact(visitor, k);

      }

    }

  }

  /** iterate objects of given Klass (objects of subtypes included) */

  public void iterateObjectsOfKlass(HeapVisitor visitor, final Klass k) {

    iterateObjectsOfKlass(visitor, k, true);

  }

  /** This routine can be used to iterate through the heap at an

      extremely low level (stepping word-by-word) to provide the

      ability to do very low-level debugging */

  public void iterateRaw(RawHeapVisitor visitor) {

    List liveRegions = collectLiveRegions();

    // Summarize size

    long totalSize = 0;

    for (int i = 0; i < liveRegions.size(); i += 2) {

      Address bottom = (Address) liveRegions.get(i);

      Address top    = (Address) liveRegions.get(i+1);

      totalSize += top.minus(bottom);

    }

    visitor.prologue(totalSize);

    for (int i = 0; i < liveRegions.size(); i += 2) {

      Address bottom = (Address) liveRegions.get(i);

      Address top    = (Address) liveRegions.get(i+1);

      // Traverses the space from bottom to top

      while (bottom.lessThan(top)) {

        visitor.visitAddress(bottom);

        bottom = bottom.addOffsetTo(VM.getVM().getAddressSize());

      }

    }

    visitor.epilogue();

  }

  public boolean isValidMethod(Address handle) {

    try {

      Method m = (Method)Metadata.instantiateWrapperFor(handle);

      return true;

    } catch (Exception e) {

      return false;

  }

  }

  // Creates an instance from the Oop hierarchy based based on the handle

  public Oop newOop(OopHandle handle) {

    // The only known way to detect the right type of an oop is

    // traversing the class chain until a well-known klass is recognized.

    // A more direct solution would require the klasses to expose

    // the C++ vtbl structure.

    // Handle the null reference

    if (handle == null) return null;

    // Then check if obj.klass() is one of the root objects

    Klass klass = Oop.getKlassForOopHandle(handle);

    if (klass != null) {

      if (klass instanceof TypeArrayKlass) return new TypeArray(handle, this);

      if (klass instanceof ObjArrayKlass) return new ObjArray(handle, this);

      if (klass instanceof InstanceKlass) return new Instance(handle, this);

    }

    if (DEBUG) {

      System.err.println("Unknown oop at " + handle);

      System.err.println("Oop's klass is " + klass);

    }

    throw new UnknownOopException();

  }

  // Print all objects in the object heap

  public void print() {

    HeapPrinter printer = new HeapPrinter(System.out);

    iterate(printer);

  }

  //---------------------------------------------------------------------------

  // Internals only below this point

  //

  private void iterateExact(HeapVisitor visitor, final Klass k) {

    iterateLiveRegions(collectLiveRegions(), visitor, new ObjectFilter() {

          public boolean canInclude(Oop obj) {

            Klass tk = obj.getKlass();

            // null Klass is seen sometimes!

            return (tk != null && tk.equals(k));

          }

        });

  }

  private void iterateSubtypes(HeapVisitor visitor, final Klass k) {

    iterateLiveRegions(collectLiveRegions(), visitor, new ObjectFilter() {

          public boolean canInclude(Oop obj) {

            Klass tk = obj.getKlass();

            // null Klass is seen sometimes!

            return (tk != null && tk.isSubtypeOf(k));

          }

        });

  }

  private void iterateLiveRegions(List liveRegions, HeapVisitor visitor, ObjectFilter of) {

    // Summarize size

    long totalSize = 0;

    for (int i = 0; i < liveRegions.size(); i += 2) {

      Address bottom = (Address) liveRegions.get(i);

      Address top    = (Address) liveRegions.get(i+1);

      totalSize += top.minus(bottom);

    }

    visitor.prologue(totalSize);

    CompactibleFreeListSpace cmsSpaceOld = null;

    CollectedHeap heap = VM.getVM().getUniverse().heap();

    if (heap instanceof GenCollectedHeap) {

      GenCollectedHeap genHeap = (GenCollectedHeap) heap;

      Generation genOld = genHeap.getGen(1);

      if (genOld instanceof ConcurrentMarkSweepGeneration) {

          ConcurrentMarkSweepGeneration concGen = (ConcurrentMarkSweepGeneration)genOld;

          cmsSpaceOld = concGen.cmsSpace();

      }

    }

    for (int i = 0; i < liveRegions.size(); i += 2) {

      Address bottom = (Address) liveRegions.get(i);

      Address top    = (Address) liveRegions.get(i+1);

      try {

        // Traverses the space from bottom to top

        OopHandle handle = bottom.addOffsetToAsOopHandle(0);

        while (handle.lessThan(top)) {

          Oop obj = null;

          // Raw pointer walk

          handle = handle.addOffsetToAsOopHandle(heap.oopOffset());

          try {

            obj = newOop(handle);

          } catch (UnknownOopException exp) {

            if (DEBUG) {

              throw new RuntimeException(" UnknownOopException  " + exp);

            }

          }

          if (obj == null) {

             //Find the object size using Printezis bits and skip over

             long size = 0;

             if ( (cmsSpaceOld != null) && cmsSpaceOld.contains(handle) ){

                 size = cmsSpaceOld.collector().blockSizeUsingPrintezisBits(handle);

             }

             if (size <= 0) {

                //Either Printezis bits not set or handle is not in cms space.

                throw new UnknownOopException();

             }

             handle = handle.addOffsetToAsOopHandle(CompactibleFreeListSpace.adjustObjectSizeInBytes(size));

             continue;

          }

          if (of == null || of.canInclude(obj)) {

                  if (visitor.doObj(obj)) {

                         // doObj() returns true to abort this loop.

                          break;

                  }

          }

          if ( (cmsSpaceOld != null) && cmsSpaceOld.contains(handle)) {

              handle = handle.addOffsetToAsOopHandle(CompactibleFreeListSpace.adjustObjectSizeInBytes(obj.getObjectSize()) );

          } else {

              handle = handle.addOffsetToAsOopHandle(obj.getObjectSize());

          }

        }

      }

      catch (AddressException e) {

        // This is okay at the top of these regions

          }

      catch (UnknownOopException e) {

        // This is okay at the top of these regions

      }

    }

    visitor.epilogue();

  }

  private static class LiveRegionsCollector implements LiveRegionsClosure {

    LiveRegionsCollector(List<Address> l) {

      liveRegions = l;

    }

    @Override

    public void doLiveRegions(LiveRegionsProvider lrp) {

      for (MemRegion reg : lrp.getLiveRegions()) {

        Address top = reg.end();

        Address bottom = reg.start();

        if (Assert.ASSERTS_ENABLED) {

          Assert.that(top != null, "top address in a live region should not be null");

        }

        if (Assert.ASSERTS_ENABLED) {

          Assert.that(bottom != null, "bottom address in a live region should not be null");

        }

        liveRegions.add(top);

        liveRegions.add(bottom);

        if (DEBUG) {

          System.err.println("Live region: " + lrp + ": " + bottom + ", " + top);

      }

    }

  }

     private List<Address> liveRegions;

  }

  // Returns a List<Address> where the addresses come in pairs. These

  // designate the live regions of the heap.

  private List<Address> collectLiveRegions() {

    // We want to iterate through all live portions of the heap, but

    // do not want to abort the heap traversal prematurely if we find

    // a problem (like an allocated but uninitialized object at the

    // top of a generation). To do this we enumerate all generations'

    // bottom and top regions, and factor in TLABs if necessary.

    // Addresses come in pairs.

    List<Address> liveRegions = new ArrayList<>();

    LiveRegionsCollector lrc = new LiveRegionsCollector(liveRegions);

    CollectedHeap heap = VM.getVM().getUniverse().heap();

    heap.liveRegionsIterate(lrc);

    // If UseTLAB is enabled, snip out regions associated with TLABs'

    // dead regions. Note that TLABs can be present in any generation.

    // FIXME: consider adding fewer boundaries to live region list.

    // Theoretically only need to stop at TLAB's top and resume at its

    // end.

    if (VM.getVM().getUseTLAB()) {

        ThreadLocalAllocBuffer tlab = thread.tlab();

        if (tlab.start() != null) {

          if ((tlab.top() == null) || (tlab.end() == null)) {

            System.err.print("Warning: skipping invalid TLAB for thread ");

            thread.printThreadIDOn(System.err);

            System.err.println();

          } else {

            if (DEBUG) {

              System.err.print("TLAB for " + thread.getThreadName() + ", #");

              thread.printThreadIDOn(System.err);

              System.err.print(": ");

              tlab.printOn(System.err);

            }

            // Go from:

            //  - below start() to start()

            //  - start() to top()

            //  - end() and above

            liveRegions.add(tlab.start());

            liveRegions.add(tlab.start());

            liveRegions.add(tlab.top());

            liveRegions.add(tlab.hardEnd());

          }

        }

      }

    }

    // Now sort live regions

    sortLiveRegions(liveRegions);

    if (Assert.ASSERTS_ENABLED) {

      Assert.that(liveRegions.size() % 2 == 0, "Must have even number of region boundaries");

    }

    if (DEBUG) {

      System.err.println("liveRegions:");

      for (int i = 0; i < liveRegions.size(); i += 2) {

          Address bottom = (Address) liveRegions.get(i);

          Address top    = (Address) liveRegions.get(i+1);

          System.err.println(" " + bottom + " - " + top);

      }

    }

    return liveRegions;

  }

  private void sortLiveRegions(List<Address> liveRegions) {

    Collections.sort(liveRegions, new Comparator<Address>() {

        public int compare(Address a1, Address a2) {

          if (AddressOps.lt(a1, a2)) {

            return -1;

          } else if (AddressOps.gt(a1, a2)) {

            return 1;

          }

          return 0;

        }

      });

  }

}