/*

   BLIS
   An object-based framework for developing high-performance BLAS-like
   libraries.

   Copyright (C) 2014, The University of Texas at Austin

   Redistribution and use in source and binary forms, with or without
   modification, are permitted provided that the following conditions are
   met:
    - Redistributions of source code must retain the above copyright
      notice, this list of conditions and the following disclaimer.
    - Redistributions in binary form must reproduce the above copyright
      notice, this list of conditions and the following disclaimer in the
      documentation and/or other materials provided with the distribution.
    - Neither the name of The University of Texas at Austin nor the names
      of its contributors may be used to endorse or promote products
      derived from this software without specific prior written permission.

   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
   HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
   DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
   THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

*/

#include "blis.h"

void bli_pool_init( dim_t   num_blocks,
                    siz_t   block_size,
                    siz_t   align_size,
                    pool_t* pool )
{
	pblk_t* block_ptrs;
	dim_t   i;

	// Allocate the block_ptrs array.
	block_ptrs = bli_malloc_intl( num_blocks * sizeof( pblk_t ) );

	// Allocate and initialize each entry in the block_ptrs array.
	for ( i = 0; i < num_blocks; ++i )
	{
		bli_pool_alloc_block( block_size, align_size, &(block_ptrs[i]) );
	}

	// Initialize the pool_t structure.
	bli_pool_set_block_ptrs( block_ptrs, pool );
	bli_pool_set_block_ptrs_len( num_blocks, pool );
	bli_pool_set_num_blocks( num_blocks, pool );
	bli_pool_set_top_index( 0, pool );
	bli_pool_set_block_size( block_size, pool );
	bli_pool_set_align_size( align_size, pool );
}

void bli_pool_finalize( pool_t* pool )
{
	pblk_t* block_ptrs;
	dim_t   num_blocks;
	dim_t   top_index;
	dim_t   i;

	// NOTE: This implementation assumes that either:
	// - all blocks have been checked in by all threads, or
	// - some subset of blocks have been checked in and the caller
	//   is bli_pool_reinit().

	// Query the current block_ptrs array.
	block_ptrs = bli_pool_block_ptrs( pool );

	// Query the total number of blocks presently allocated.
	num_blocks = bli_pool_num_blocks( pool );

	// Query the top_index of the pool.
	top_index  = bli_pool_top_index( pool );

	// Free the individual blocks currently in the pool.
	for ( i = top_index; i < num_blocks; ++i )
	{
		bli_pool_free_block( &(block_ptrs[i]) );
	}

	// Free the block_ptrs array.
	bli_free_intl( block_ptrs );

	// This explicit clearing of the pool_t struct is not strictly
	// necessary and so it has been commented out.
#if 0
	// Clear the contents of the pool_t struct.
	bli_pool_set_block_ptrs( NULL, pool );
	bli_pool_set_block_ptrs_len( 0, pool );
	bli_pool_set_num_blocks( 0, pool );
	bli_pool_set_top_index( 0, pool );
	bli_pool_set_block_size( 0, pool );
	bli_pool_set_align_size( 0, pool );
#endif
}

void bli_pool_reinit( dim_t   num_blocks_new,
                      siz_t   block_size_new,
                      siz_t   align_size_new,
                      pool_t* pool )
{
	// Finalize the pool as it is currently configured. If some blocks
	// are still checked out to threads, those blocks are not freed
	// here, and instead will be freed when the threads are ready to
	// release the blocks. (This will happen because the threads will
	// notice that the block size of the pool has changed.)
	bli_pool_finalize( pool );

	// Reinitialize the pool with the new parameters, in particular,
	// the new block size.
	bli_pool_init( num_blocks_new, block_size_new, align_size_new, pool );
}

void bli_pool_checkout_block( siz_t req_size, pblk_t* block, pool_t* pool )
{
	pblk_t* block_ptrs;
	dim_t   top_index;

	if ( bli_pool_block_size( pool ) < req_size )
	{
		const dim_t num_blocks_new = bli_pool_num_blocks( pool );
		const siz_t align_size_new = bli_pool_align_size( pool );

		// If the requested block size is smaller than what the pool
		// was initialized with, reinitialize the pool to contain blocks
		// of the requested size.
		bli_pool_reinit( num_blocks_new,
		                 req_size,
		                 align_size_new,
		                 pool );
	}

	// If the pool is exhausted, add a block.
	if ( bli_pool_is_exhausted( pool ) )
	{
		bli_pool_grow( 1, pool );
	}

	// At this point, at least one block is guaranteed to be available.

	// Query the current block_ptrs array.
	block_ptrs = bli_pool_block_ptrs( pool );

	// Query the top_index of the pool.
	top_index = bli_pool_top_index( pool );

	// Copy the block at top_index to the caller's pblk_t struct.
	//bli_pblk_copy( *(block_ptrs[top_index]), *block );
	*block = block_ptrs[top_index];

	// Notice that we don't actually need to clear the contents of
	// block_ptrs[top_index]. It will get overwritten eventually when
	// the block is checked back in.
	bli_pblk_clear( &block_ptrs[top_index] );

	// Increment the pool's top_index.
	bli_pool_set_top_index( top_index + 1, pool );
}

void bli_pool_checkin_block( pblk_t* block, pool_t* pool )
{
	pblk_t* block_ptrs;
	dim_t   top_index;

	// Query the current block_ptrs array.
	block_ptrs = bli_pool_block_ptrs( pool );

	// Query the top_index of the pool.
	top_index = bli_pool_top_index( pool );

	// Copy the caller's pblk_t struct to the block at top_index - 1.
	//bli_pblk_copy( *(block_ptrs[top_index-1]), *block );
	block_ptrs[top_index-1] = *block;

	// Decrement the pool's top_index.
	bli_pool_set_top_index( top_index - 1, pool );
}

void bli_pool_grow( dim_t num_blocks_add, pool_t* pool )
{
	pblk_t* block_ptrs_cur;
	dim_t   block_ptrs_len_cur;
	dim_t   num_blocks_cur;

	pblk_t* block_ptrs_new;
	dim_t   num_blocks_new;

	siz_t   block_size;
	siz_t   align_size;
	dim_t   top_index;

	dim_t   i;

	// If the requested increase is zero (or negative), return early.
	if ( num_blocks_add < 1 ) return;

	// Query the allocated length of the block_ptrs array and also the
	// total number of blocks allocated.
	block_ptrs_len_cur = bli_pool_block_ptrs_len( pool );
	num_blocks_cur     = bli_pool_num_blocks( pool );

	// Compute the total number of allocated blocks that will exist
	// after we grow the pool.
	num_blocks_new = num_blocks_cur + num_blocks_add;

	// If the new total number of allocated blocks is larger than the
	// allocated length of the block_ptrs array, we need to allocate
	// a new (larger) block_ptrs array.
	if ( num_blocks_new > block_ptrs_len_cur )
	{
		// Query the current block_ptrs array.
		block_ptrs_cur = bli_pool_block_ptrs( pool );

		// Allocate a new block_ptrs array of length num_blocks_new.
		block_ptrs_new = bli_malloc_intl( num_blocks_new * sizeof( pblk_t ) );

		// Query the top_index of the pool.
		top_index = bli_pool_top_index( pool );

		// Copy the contents of the old block_ptrs array to the new/resized
		// array. Notice that we can begin with top_index since all entries
		// from 0 to top_index-1 have been checked out to threads.
		for ( i = top_index; i < num_blocks_cur; ++i ) 
		{
//printf( "bli_pool_grow: copying from %lu\n", top_index );
			block_ptrs_new[i] = block_ptrs_cur[i];
		}

//printf( "bli_pool_grow: bp_cur: %p\n", block_ptrs_cur );
		// Free the old block_ptrs array.
		bli_free_intl( block_ptrs_cur );

		// Update the pool_t struct with the new block_ptrs array and
		// record its allocated length.
		bli_pool_set_block_ptrs( block_ptrs_new, pool );
		bli_pool_set_block_ptrs_len( num_blocks_new, pool );
	}

	// At this point, we are guaranteed to have enough unused elements
	// in the block_ptrs array to accommodate an additional num_blocks_add
	// blocks.

	// Query the current block_ptrs array (which was possibly just resized).
	block_ptrs_cur = bli_pool_block_ptrs( pool );

	// Query the block size and alignment size of the current pool.
	block_size = bli_pool_block_size( pool );
	align_size = bli_pool_align_size( pool );

	// Allocate the requested additional blocks in the resized array.
	for ( i = num_blocks_cur; i < num_blocks_new; ++i ) 
	{
//printf( "libblis: growing pool, block_size = %lu\n", block_size ); fflush( stdout );

		bli_pool_alloc_block( block_size, align_size, &(block_ptrs_cur[i]) );
	}

	// Update the pool_t struct with the new number of allocated blocks.
	// Notice that top_index remains unchanged, as do the block_size and
	// align_size fields.
	bli_pool_set_num_blocks( num_blocks_new, pool );
}

void bli_pool_shrink( dim_t num_blocks_sub, pool_t* pool )
{
	pblk_t* block_ptrs;
	dim_t   num_blocks;
	dim_t   num_blocks_avail;
	dim_t   num_blocks_new;

	dim_t   top_index;

	dim_t   i;

	// Query the total number of blocks presently allocated.
	num_blocks = bli_pool_num_blocks( pool );

	// Query the top_index of the pool.
	top_index = bli_pool_top_index( pool );

	// Compute the number of blocks available to be checked out
	// (and thus available for removal).
	num_blocks_avail = num_blocks - top_index;

	// If the requested decrease is more than the number of available
	// blocks in the pool, only remove the number of blocks available.
	if ( num_blocks_avail < num_blocks_sub )
		num_blocks_sub = num_blocks_avail;

	// If the effective requested decrease is zero (or the requested
	// decrease was negative), return early.
	if ( num_blocks_sub < 1 ) return;

	// Query the current block_ptrs array.
	block_ptrs = bli_pool_block_ptrs( pool );

	// Compute the new total number of blocks.
	num_blocks_new = num_blocks - num_blocks_sub;

	// Free the individual blocks.
	for ( i = num_blocks_new; i < num_blocks; ++i )
	{
		bli_pool_free_block( &(block_ptrs[i]) );
	}

	// Update the pool_t struct.
	bli_pool_set_num_blocks( num_blocks_new, pool );

	// Note that after shrinking the pool, num_blocks < block_ptrs_len.
	// This means the pool can grow again by num_blocks_sub before
	// a re-allocation of block_ptrs is triggered.
}

void bli_pool_alloc_block( siz_t   block_size,
                           siz_t   align_size,
                           pblk_t* block )
{
	void* buf_sys;
	void* buf_align;

	// Allocate the block. We add the alignment size to ensure we will
	// have enough usable space after alignment.
	buf_sys   = bli_malloc_pool( block_size + align_size );
	buf_align = buf_sys;

	// Advance the pointer to achieve the necessary alignment, if it is not
	// already aligned.
	if ( bli_is_unaligned_to( ( siz_t )buf_sys, ( siz_t )align_size ) )
	{
		// C99's stdint.h guarantees that a void* can be safely cast to a
		// uintptr_t and then back to a void*, hence the casting of buf_sys
		// and align_size to uintptr_t. buf_align is initially cast to char*
		// to allow pointer arithmetic in units of bytes, and then advanced
		// to the next nearest alignment boundary, and finally cast back to
		// void* before being stored. Notice that the arithmetic works even
		// if the alignment value is not a power of two.
		buf_align = ( void* )(   ( char*     )buf_align +
		                       ( ( uintptr_t )align_size -
		                         ( uintptr_t )buf_sys %
		                         ( uintptr_t )align_size )
		                     );
	}
	
	// Save the results in the pblk_t structure.
	bli_pblk_set_buf_sys( buf_sys, block );
	bli_pblk_set_buf_align( buf_align, block );
}

void bli_pool_free_block( pblk_t* block )
{
	void* buf_sys;

	// Extract the pointer to the block that was originally provided by
	// the operating system.
	buf_sys = bli_pblk_buf_sys( block );

	// Free the block.
	bli_free_pool( buf_sys );
}

void bli_pool_print( pool_t* pool )
{
	pblk_t* block_ptrs     = bli_pool_block_ptrs( pool );
	dim_t   block_ptrs_len = bli_pool_block_ptrs_len( pool );
	dim_t   top_index      = bli_pool_top_index( pool );
	dim_t   num_blocks     = bli_pool_num_blocks( pool );
	dim_t   block_size     = bli_pool_block_size( pool );
	dim_t   align_size     = bli_pool_align_size( pool );
	dim_t   i;

	printf( "pool struct ---------------\n" );
	printf( "  block_ptrs:      %p\n", block_ptrs );
	printf( "  block_ptrs_len:  %ld\n", ( long )block_ptrs_len );
	printf( "  top_index:       %ld\n", ( long )top_index );
	printf( "  num_blocks:      %ld\n", ( long )num_blocks );
	printf( "  block_size:      %ld\n", ( long )block_size );
	printf( "  align_size:      %ld\n", ( long )align_size );
	printf( "  pblks   sys    align\n" );
	for ( i = 0; i < num_blocks; ++i )
	{
		printf( "  %ld: %p %p\n", ( long )i,
		                          bli_pblk_buf_sys(   &block_ptrs[i] ),
	                              bli_pblk_buf_align( &block_ptrs[i] ) );
	}
}

void bli_pblk_print( pblk_t* pblk )
{
	void* buf_sys   = bli_pblk_buf_sys( pblk );
	void* buf_align = bli_pblk_buf_align( pblk );

	printf( "pblk struct ---------------\n" );
	printf( "     %p %p\n", buf_sys, buf_align );
}

