// SPDX-License-Identifier: EPL-2.0 OR GPL-2.0-or-later
// SPDX-FileCopyrightText: Bradley M. Bell <bradbell@seanet.com>
// SPDX-FileContributor: 2003-22 Bradley M. Bell
// ----------------------------------------------------------------------------

/*
{xrst_begin thread_alloc.cpp}

Fast Multi-Threading Memory Allocator: Example and Test
#######################################################

{xrst_literal
   // BEGIN C++
   // END C++
}

{xrst_end thread_alloc.cpp}
*/
// BEGIN C++
# include <cppad/utility/thread_alloc.hpp>
# include <vector>
# include <limits>


namespace { // Begin empty namespace



bool raw_allocate(void)
{  bool ok = true;
   using CppAD::thread_alloc;
   size_t thread;

   // check that no memory is initilaly inuse
   ok &= thread_alloc::free_all();

   // amount of static memory used by thread zero
   size_t static_inuse = 0;

   // repeatedly allocate enough memory for at least two size_t values.
   size_t min_size_t = 2;
   size_t min_bytes  = min_size_t * sizeof(size_t);
   size_t n_outer   = 10;
   size_t n_inner    = 5;
   for(size_t i = 0; i < n_outer; i++)
   {  // Do not use CppAD::vector here because its use of thread_alloc
      // complicates the inuse and available results.
      std::vector<void*> v_ptr(n_inner);
      // cap_bytes will be set by get_memory
      size_t cap_bytes = 0; // set here to avoid MSC warning
      for(size_t j = 0; j < n_inner; j++)
      {  // allocate enough memory for min_size_t size_t objects
         v_ptr[j]    = thread_alloc::get_memory(min_bytes, cap_bytes);
         size_t* ptr = reinterpret_cast<size_t*>(v_ptr[j]);
         // determine the number of size_t values we have obtained
         size_t  cap_size_t = cap_bytes / sizeof(size_t);
         ok                &= min_size_t <= cap_size_t;
         // use placement new to call the size_t copy constructor
         for(size_t k = 0; k < cap_size_t; k++)
            new(ptr + k) size_t(i + j + k);
         // check that the constructor worked
         for(size_t k = 0; k < cap_size_t; k++)
            ok &= ptr[k] == (i + j + k);
      }
      // check that n_inner * cap_bytes are inuse and none are available
      thread = thread_alloc::thread_num();
      ok &= thread_alloc::inuse(thread) == n_inner*cap_bytes + static_inuse;
      ok &= thread_alloc::available(thread) == 0;
      // return the memrory to thread_alloc
      for(size_t j = 0; j < n_inner; j++)
         thread_alloc::return_memory(v_ptr[j]);
      // check that now n_inner * cap_bytes are now available
      // and none are in use
      ok &= thread_alloc::inuse(thread) == static_inuse;
      ok &= thread_alloc::available(thread) == n_inner * cap_bytes;
   }
   thread_alloc::free_available(thread);

   // check that the tests have not held onto memory
   ok &= thread_alloc::free_all();

   return ok;
}

class my_char {
public:
   char ch_ ;
   my_char(void) : ch_(' ')
   { }
   my_char(const my_char& my_ch) : ch_(my_ch.ch_)
   { }
};

bool type_allocate(void)
{  bool ok = true;
   using CppAD::thread_alloc;
   size_t i;

   // check initial memory values
   size_t thread = thread_alloc::thread_num();
   ok &= thread == 0;
   ok &= thread_alloc::free_all();
   size_t static_inuse = 0;

   // initial allocation of an array
   size_t  size_min  = 3;
   size_t  size_one;
   my_char *array_one  =
      thread_alloc::create_array<my_char>(size_min, size_one);

   // check the values and change them to null 'x'
   for(i = 0; i < size_one; i++)
   {  ok &= array_one[i].ch_ == ' ';
      array_one[i].ch_ = 'x';
   }

   // now create a longer array
   size_t size_two;
   my_char *array_two =
      thread_alloc::create_array<my_char>(2 * size_min, size_two);

   // check the values in array one
   for(i = 0; i < size_one; i++)
      ok &= array_one[i].ch_ == 'x';

   // check the values in array two
   for(i = 0; i < size_two; i++)
      ok &= array_two[i].ch_ == ' ';

   // check the amount of inuse and available memory
   // (an extra size_t value is used for each memory block).
   size_t check = static_inuse + sizeof(my_char)*(size_one + size_two);
   ok   &= thread_alloc::inuse(thread) - check < sizeof(my_char);
   ok   &= thread_alloc::available(thread) == 0;

   // delete the arrays
   thread_alloc::delete_array(array_one);
   thread_alloc::delete_array(array_two);
   ok   &= thread_alloc::inuse(thread) == static_inuse;
   check = sizeof(my_char)*(size_one + size_two);
   ok   &= thread_alloc::available(thread) - check < sizeof(my_char);

   // free the memory for use by this thread
   thread_alloc::free_available(thread);

   // check that the tests have not held onto memory
   ok &= thread_alloc::free_all();

   return ok;
}

} // End empty namespace

bool check_alignment(void)
{  bool ok = true;
   using CppAD::thread_alloc;

   // number of binary digits in a size_t value
   size_t n_digit = std::numeric_limits<size_t>::digits;

   // must be a multiple of 8
   ok &= (n_digit % 8) == 0;

   // number of bytes in a size_t value
   size_t n_byte  = n_digit / 8;

   // check raw allocation -------------------------------------------------
   size_t min_bytes = 1;
   size_t cap_bytes;
   void* v_ptr = thread_alloc::get_memory(min_bytes, cap_bytes);

   // convert to a size_t value
   size_t v_size_t = reinterpret_cast<size_t>(v_ptr);

   // check that it is aligned
   ok &= (v_size_t % n_byte) == 0;

   // return memory to available pool
   thread_alloc::return_memory(v_ptr);

   // check array allocation ----------------------------------------------
   size_t size_min = 1;
   size_t size_out;
   my_char *array_ptr =
      thread_alloc::create_array<my_char>(size_min, size_out);

   // convert to a size_t value
   size_t array_size_t = reinterpret_cast<size_t>(array_ptr);

   // check that it is aligned
   ok &= (array_size_t % n_byte) == 0;

   // return memory to available pool
   thread_alloc::delete_array(array_ptr);

   return ok;
}


bool thread_alloc(void)
{  bool ok  = true;
   using CppAD::thread_alloc;

   // check that there is only on thread
   ok  &= thread_alloc::num_threads() == 1;
   // so thread number must be zero
   ok  &= thread_alloc::thread_num() == 0;
   // and we are in sequential execution mode
   ok  &= thread_alloc::in_parallel() == false;

   // Instruct thread_alloc to hold onto memory.  This makes memory
   // allocation faster (especially when there are multiple threads).
   thread_alloc::hold_memory(true);

   // run raw allocation tests
   ok &= raw_allocate();

   // run typed allocation tests
   ok &= type_allocate();

   // check alignment
   ok &= check_alignment();

   // return allocator to its default mode
   thread_alloc::hold_memory(false);
   return ok;
}


// END C++
