//===--------- VirtualMachine.h - Registering a VM ------------------------===//
//
//                            The VMKit project
//
// This file is distributed under the University of Pierre et Marie Curie 
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//

#ifndef MVM_VIRTUALMACHINE_H
#define MVM_VIRTUALMACHINE_H

#include "llvm/ADT/DenseMap.h"

#include "mvm/Allocator.h"
#include "mvm/Threads/CollectionRV.h"
#include "mvm/Threads/Locks.h"
#include "mvm/GC/GC.h"

#include <cassert>
#include <map>

namespace mvm {

class CompiledFrames;
class FrameInfo;
class Frames;

class FunctionMap {
public:
  /// Functions - Map of applicative methods to function pointers. This map is
  /// used when walking the stack so that VMKit knows which applicative method
  /// is executing on the stack.
  ///
  llvm::DenseMap<word_t, FrameInfo*> Functions;

  /// FunctionMapLock - Spin lock to protect the Functions map.
  ///
  mvm::SpinLock FunctionMapLock;

  /// IPToFrameInfo - Map a code start instruction instruction to the FrameInfo.
  ///
  FrameInfo* IPToFrameInfo(word_t ip);

  /// addFrameInfo - A new instruction pointer in the function map.
  ///
  void addFrameInfo(word_t ip, FrameInfo* meth);
  void addFrameInfoNoLock(word_t ip, FrameInfo* meth) {
    Functions[ip] = meth;
  }
  /// removeFrameInfos - Remove all FrameInfo owned by the given owner.
  void removeFrameInfos(void* owner) {} /* TODO */

  FunctionMap(BumpPtrAllocator& allocator, CompiledFrames** frames);
};

/// VirtualMachine - This class is the root of virtual machine classes. It
/// defines what a VM should be.
///
class VirtualMachine : public mvm::PermanentObject {
protected:
  VirtualMachine(BumpPtrAllocator &Alloc, CompiledFrames** frames) :
		  allocator(Alloc), FunctionsCache(Alloc, frames) {
    mainThread = NULL;
    numberOfThreads = 0;
    doExit = false;
    exitingThread = NULL;
  }

  virtual ~VirtualMachine() {
  }

public:

  /// allocator - Bump pointer allocator to allocate permanent memory
  /// related to this VM.
  ///
  mvm::BumpPtrAllocator& allocator;

//===----------------------------------------------------------------------===//
// (1) Thread-related methods.
//===----------------------------------------------------------------------===//

  /// mainThread - The main thread of this VM.
  ///
  mvm::Thread* mainThread;

  /// NumberOfThreads - The number of threads that currently run under this VM.
  ///
  uint32_t numberOfThreads;

  /// ThreadLock - Lock to create or destroy a new thread.
  ///
  mvm::LockNormal threadLock;

  /// ThreadVar - Condition variable to wake up the thread manager.
  mvm::Cond threadVar;

  /// exitingThread - Thread that is currently exiting. Used by the thread
  /// manager to free the resources (stack) used by a thread.
  mvm::Thread* exitingThread;

  /// doExit - Should the VM exit now?
  bool doExit;
  
  /// setMainThread - Set the main thread of this VM.
  ///
  void setMainThread(mvm::Thread* th) { mainThread = th; }
  
  /// getMainThread - Get the main thread of this VM.
  ///
  mvm::Thread* getMainThread() const { return mainThread; }

  /// addThread - Add a new thread to the list of threads.
  ///
  void addThread(mvm::Thread* th) {
    threadLock.lock();
    numberOfThreads++;
    if (th != mainThread) {
      if (mainThread) th->append(mainThread);
      else mainThread = th;
    }
    threadLock.unlock();
  }
  
  /// removeThread - Remove the thread from the list of threads.
  ///
  void removeThread(mvm::Thread* th) {
    threadLock.lock();
    while (exitingThread != NULL) {
      // Make sure the thread manager had a chance to consume the previous
      // dead thread.
      threadLock.unlock();
      Thread::yield();
      threadLock.lock();
    }
    numberOfThreads--;
    if (mainThread == th) mainThread = (Thread*)th->next();
    th->remove();
    if (numberOfThreads == 0) mainThread = NULL;
    exitingThread = th;
    threadVar.signal();
    threadLock.unlock();
  }

  /// exit - Exit this virtual machine.
  void exit();

  /// waitForExit - Wait until the virtual machine stops its execution.
  void waitForExit();

//===----------------------------------------------------------------------===//
// (2) GC-related methods.
//===----------------------------------------------------------------------===//

  /// startCollection - Preliminary code before starting a GC.
  ///
  virtual void startCollection() {}
  
  /// endCollection - Code after running a GC.
  ///
  virtual void endCollection() {}
  
  /// scanWeakReferencesQueue - Scan all weak references. Called by the GC
  /// before scanning the finalization queue.
  /// 
  virtual void scanWeakReferencesQueue(word_t closure) {}
  
  /// scanSoftReferencesQueue - Scan all soft references. Called by the GC
  /// before scanning the finalization queue.
  ///
  virtual void scanSoftReferencesQueue(word_t closure) {}
  
  /// scanPhantomReferencesQueue - Scan all phantom references. Called by the GC
  /// after the finalization queue.
  ///
  virtual void scanPhantomReferencesQueue(word_t closure) {}

  /// scanFinalizationQueue - Scan objets with a finalized method and schedule
  /// them for finalization if they are not live.
  /// 
  virtual void scanFinalizationQueue(word_t closure) {}

  /// addFinalizationCandidate - Add an object to the queue of objects with
  /// a finalization method.
  ///
  virtual void addFinalizationCandidate(gc* object) {}

  /// tracer - Trace this virtual machine's GC-objects.
  ///
  virtual void tracer(word_t closure) {}

  /// getObjectSize - Get the size of this object. Used by copying collectors.
  ///
  virtual size_t getObjectSize(gc* object) = 0;

  /// getObjectTypeName - Get the type of this object. Used by the GC for
  /// debugging purposes.
  ///
  virtual const char* getObjectTypeName(gc* object) { return "An object"; }

  /// rendezvous - The rendezvous implementation for garbage collection.
  ///
  CooperativeCollectionRV rendezvous;

//===----------------------------------------------------------------------===//
// (3) Backtrace-related methods.
//===----------------------------------------------------------------------===//

  FunctionMap FunctionsCache;
  FrameInfo* IPToFrameInfo(word_t ip) {
    return FunctionsCache.IPToFrameInfo(ip);
  }
  void removeFrameInfos(void* owner) {
    FunctionsCache.removeFrameInfos(owner);
  }

  virtual void printMethod(FrameInfo* FI, word_t ip, word_t addr) = 0;
  
//===----------------------------------------------------------------------===//
// (4) Launch-related methods.
//===----------------------------------------------------------------------===//

  /// runApplication - Run an application. The application name is in
  /// the arguments, hence it is the virtual machine's job to parse them.
  virtual void runApplication(int argc, char** argv) = 0;
};

} // end namespace mvm
#endif // MVM_VIRTUALMACHINE_H