!include once #1027304 // Eclipse Collections

import org.eclipse.collections.impl.set.mutable.primitive.*;
import org.eclipse.collections.api.iterator.*;

sclass ManagedIntObjects_v1_Collector implements IManagedObjectCollector {
  ManagedIntObjects_v1 mem;
  CompactTreeSet<IntRange> objects = new(intRangeComparatorByStart());
  new IntHashSet pointers;
  IntIntHashMap relocationMap;
  
  // TODO: turn into a set
  new MultiMap<Int, IVF1<Int>> relocationCallbacks;

  bool discardFreeListEarly; // saves memory, but ironically makes original memory unusable when compacting fails because of OOM
  bool verbose = true;
  
  *(ManagedIntObjects_v1 *mem) {}
  
  // notify collector that there is an object in a location
  public void noteObject(int start, int size, IVF1<Int> updateAddress default null) {
    objects.add(intRange(start, start+size));
    if (updateAddress != null)
      relocationCallbacks.add(start, updateAddress);
  }
  
  // notify collector that there is a pointer in a location
  public void notePointer(int addr) {
    if (addr != 0)
      pointers.add(addr);
  }
  
  // notify collector that there is a pointer array in a location
  public void notePointerArray(int start) {
    if (start == 0) ret;
    int n = mem.get(start);
    noteObject(start, n+1);
    for i to n:
      notePointer(start+1+i);
  }
  
  int sizeNeeded() {
    ret totalIntRangesLength_int(objects);
  }
  
  void collectAndCompact() {
    int sizeNeeded = sizeNeeded();
    if (mem.size() == sizeNeeded) ret;
    
    if (discardFreeListEarly) mem.freeList.clear();
    
    // reserve new memory
    print("Reserving " + toM(sizeNeeded*(long) mem.wordSizeInBytes()) + " MB");
    int freePtr = mem.reservedSpaceAtBeginning();
    int[] newMem = new[freePtr+sizeNeeded];
    
    // copy all the objects, fill relocationMap
    print("Copying " + nObjects(objects));
    for (IntRange r : objects) {
      int oldPtr = r.start, newPtr = freePtr;
      if (oldPtr != newPtr) {
        relocationMap.put(oldPtr, newPtr);
        for (IVF1<Int> f : relocationCallbacks.get(oldPtr))
          f.get(freePtr);
      }
      arraycopy(mem.mem, r.start, newMem, freePtr, r.length());
      freePtr += r.length();
    }
    
    // update the pointers
    print("Updating " + n2(pointers.size(), "pointer"));
    IntIterator itPointers = pointers.intIterator();
    while (itPointers.hasNext()) {
      int pointerAddr = itPointers.next();
      
      // find enclosing object
      IntRange obj = objects.floor(IntRange(pointerAddr, pointerAddr));
      if (obj == null) continue with print("Pointer without object");
      
      int newObjAddr = relocationMap.getIfAbsent(obj.start, obj.start);
      int newPointerAddr = newObjAddr-obj.start+pointerAddr;
      
      // find target, update pointer
      int target = mem.get(pointerAddr);
      if (target == 0) continue;
      
      int newTarget = relocationMap.getIfAbsent(target, -1);
      if (newTarget >= 0)
        newMem[newPointerAddr] = newTarget;
    }
    
    print("Managed GC done");
    mem.mem = newMem;
    if (!discardFreeListEarly) mem.freeList.clear();
  }
  
  // call after collectAndCompact to get new location of objects
  public int getNewLocation(int addr) {
    ret relocationMap.getIfAbsent(addr, addr);
  }
}