dbm_shard.h

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/*----------------------------------------------------------------------------*/
/*  CP2K: A general program to perform molecular dynamics simulations         */
/*  Copyright 2000-2026 CP2K developers group <https://cp2k.org>              */
/*                                                                            */
/*  SPDX-License-Identifier: BSD-3-Clause                                     */
/*----------------------------------------------------------------------------*/
#ifndef DBM_SHARD_H
#define DBM_SHARD_H
 
#include <omp.h>
 
#ifdef __cplusplus
extern "C" {
#endif
 
/*******************************************************************************
 * \brief Internal struct for storing a block's metadata.
 * \author Ole Schuett
 ******************************************************************************/
typedef struct {
  int row;
  int col;
  int offset;
} dbm_block_t;
 
/*******************************************************************************
 * \brief Internal struct for storing a matrix shard.
 * \author Ole Schuett
 ******************************************************************************/
typedef struct {
  int nblocks;
  int nblocks_allocated;
  dbm_block_t *blocks;
 
  int hashtable_size;  // should be a power of two
  int hashtable_prime; // should be a coprime of hashtable_size
  int *hashtable;      // maps row/col to block numbers
 
  int data_promised;  // ref'd by dbm_block_t.offset (not yet allocated)
  int data_allocated; // actually allocated (capacity of data buffer)
  int data_size;      // actually allocated and initialized
  double *data;       // potentially over-allocated (to amortize resizing)
 
  omp_lock_t lock; // used by dbm_put_block
} dbm_shard_t;
 
/*******************************************************************************
 * \brief Internal routine for initializing a shard.
 * \author Ole Schuett
 ******************************************************************************/
void dbm_shard_init(dbm_shard_t *shard);
 
/*******************************************************************************
 * \brief Internal routine for copying content of shard_b into shard_a.
 * \author Ole Schuett
 ******************************************************************************/
void dbm_shard_copy(dbm_shard_t *shard_a, const dbm_shard_t *shard_b);
 
/*******************************************************************************
 * \brief Internal routine for releasing a shard.
 * \author Ole Schuett
 ******************************************************************************/
void dbm_shard_release(dbm_shard_t *shard);
 
/*******************************************************************************
 * \brief Internal routine for looking up a block from a shard.
 * \author Ole Schuett
 ******************************************************************************/
dbm_block_t *dbm_shard_lookup(const dbm_shard_t *shard, const int row,
                              const int col);
 
/*******************************************************************************
 * \brief Internal routine for allocating the metadata of a new block.
 * \author Ole Schuett
 ******************************************************************************/
dbm_block_t *dbm_shard_promise_new_block(dbm_shard_t *shard, const int row,
                                         const int col, const int block_size);
 
/*******************************************************************************
 * \brief Internal routine for allocating and zeroing any promised block's data.
 * \author Ole Schuett
 ******************************************************************************/
void dbm_shard_allocate_promised_blocks(dbm_shard_t *shard);
 
/*******************************************************************************
 * \brief Internal routine for getting block or promising a new one.
 * \author Ole Schuett
 ******************************************************************************/
dbm_block_t *dbm_shard_get_or_promise_block(dbm_shard_t *shard, const int row,
                                            const int col,
                                            const int block_size);
 
/*******************************************************************************
 * \brief Internal routine for getting block or allocating a new one.
 * \author Ole Schuett
 ******************************************************************************/
dbm_block_t *dbm_shard_get_or_allocate_block(dbm_shard_t *shard, const int row,
                                             const int col,
                                             const int block_size);
 
#ifdef __cplusplus
}
#endif
 
#endif
 
// EOF