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//
// G4PDefManager
//
// Class description:
//
// Utility template class for splitting read/write data for
// thread-safety from classes: G4ParticleDefinition, G4VDecayChannel.
//
// The type G4PDefManager is introduced to encapsulate the methods used by
// both the master thread and worker threads to allocate memory space for
// the fields encapsulated by the class G4PDefData. When each thread
// changes the value for these fields, it refers to them using a macro
// definition defined below. For every G4ParticleDefinition instance,
// there is a corresponding G4PDefData instance. All G4PDefData instances
// are organized by the class G4PDefManager as an array.
// The field "int g4particleDefinitionInstanceID" is added to the class
// G4ParticleDefinition.
// The value of this field in each G4ParticleDefinition instance is the
// subscript of the corresponding G4PDefData instance.
// In order to use the class G4PDefManager, we add a static member in the
// class G4ParticleDefinition as follows:
// "static G4PDefManager subInstanceManager".
// Both the master thread and worker threads change the length of the array
// for G4PDefData instances mutually along with G4ParticleDefinition
// instances are created. For each worker thread, it dynamically creates ions.
// Consider any thread A, if there is any other thread which creates an ion.
// This ion is shared by the thread A. So the thread A leaves an empty space
// in the array of G4PDefData instances for the ion.

// Author: Xin Dong, 25.01.2009 - First implementation
//                                from automatic MT conversion
// --------------------------------------------------------------------
#ifndef G4PDefManager_hh
#define G4PDefManager_hh

#include "G4AutoLock.hh"
#include "globals.hh"

#include "pwdefs.hh"
#include <stdlib.h>

class G4ProcessManager;
class G4VTrackingManager;

class G4PDefData
{
    // G4PDefData is the private data from the object to be split.
    // Encapsulates the fields of the class G4ParticleDefinition
    // that may not be read-only.

  public:
    void initialize();

    G4ProcessManager* theProcessManager = nullptr;
    G4VTrackingManager* theTrackingManager = nullptr;
};

class G4PDefManager
{
  public:
    G4PDefManager();

    // Invoked by the master or work thread to create a new subinstance
    // whenever a new split class instance is created. For each worker
    // thread, ions are created dynamically.
    G4int CreateSubInstance();

    // Invoked by each worker thread to grow the subinstance array and
    // initialize each new subinstance using a particular method defined
    // by the subclass.
    void NewSubInstances();

    // Invoked by all threads to free the subinstance array.
    void FreeSlave();

    G4PDefData* GetOffset();

    void UseWorkArea(G4PDefData* newOffset);

    G4PDefData* FreeWorkArea();

    G4PART_DLL static G4int& slavetotalspace();  // thread-local
    G4PART_DLL static G4PDefData*& offset();  // thread-local

  private:
    G4int totalobj{0};
    G4Mutex mutex;
};

#endif