star-hitran

Load line-by-line data from the HITRAN database
git clone git://git.meso-star.fr/star-hitran.git
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shtr_cache.c (3989B)

      1 /* Copyright (C) 2022, 2025, 2026 |Méso|Star> (contact@meso-star.com)
      2  * Copyright (C) 2025, 2026 Université de Lorraine
      3  * Copyright (C) 2022 Centre National de la Recherche Scientifique
      4  * Copyright (C) 2022 Université Paul Sabatier
      5  *
      6  * This program is free software: you can redistribute it and/or modify
      7  * it under the terms of the GNU General Public License as published by
      8  * the Free Software Foundation, either version 3 of the License, or
      9  * (at your option) any later version.
     10  *
     11  * This program is distributed in the hope that it will be useful,
     12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
     13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
     14  * GNU General Public License for more details.
     15  *
     16  * You should have received a copy of the GNU General Public License
     17  * along with this program. If not, see <http://www.gnu.org/licenses/>. */
     18 
     19 #include "shtr_c.h"
     20 #include "shtr_cache.h"
     21 
     22 #include <rsys/cstr.h>
     23 #include <rsys/mutex.h>
     24 #include <rsys/ref_count.h>
     25 
     26 #include <string.h> /* memcpy */
     27 
     28 #define CHUNK_ID_NONE SIZE_MAX
     29 
     30 /* Simple, dumb cache structure storing uncompressed lines from the last chunk
     31  * accessed. It should improve linear access performance, but not random access
     32  * performance, which will be disastrous because most accesses will require
     33  * decompressing an entire block of lines, only one of which will be accessed
     34  * before the block is discarded.
     35  *
     36  * TODO: implement a more general LRU cache */
     37 struct cache {
     38   size_t chunk_id;
     39   struct line lines[NLINES_PER_CHUNK];
     40 
     41   struct mutex* mutex;
     42   struct shtr* shtr;
     43   ref_T ref;
     44 };
     45 
     46 /*******************************************************************************
     47  * Helper functions
     48  ******************************************************************************/
     49 static void
     50 release_cache(ref_T* ref)
     51 {
     52   struct cache* cache = CONTAINER_OF(ref, struct cache, ref);
     53   struct shtr* shtr = NULL;
     54   ASSERT(ref);
     55   shtr = cache->shtr;
     56   if(cache->mutex) mutex_destroy(cache->mutex);
     57   MEM_RM(shtr->allocator, cache);
     58   SHTR(ref_put(shtr));
     59 }
     60 
     61 /*******************************************************************************
     62  * Local functions
     63  ******************************************************************************/
     64 res_T
     65 cache_create(struct shtr* shtr, struct cache** out_cache)
     66 {
     67   struct cache* cache = NULL;
     68   res_T res = RES_OK;
     69 
     70   ASSERT(shtr && out_cache); /* Pre-conditions */
     71 
     72   cache = MEM_CALLOC(shtr->allocator, 1, sizeof(*cache));
     73   if(!cache) { res = RES_MEM_ERR; goto error; }
     74   ref_init(&cache->ref);
     75   SHTR(ref_get(shtr));
     76   cache->shtr = shtr;
     77   cache->chunk_id = CHUNK_ID_NONE;
     78 
     79   cache->mutex = mutex_create();
     80   if(!cache->mutex) { res = RES_MEM_ERR; goto error; }
     81 
     82 exit:
     83   *out_cache = cache;
     84   return res;
     85 error:
     86   ERROR(shtr, "Error creating line cache -- %s\n", res_to_cstr(res));
     87   if(cache) { cache_ref_put(cache); cache = NULL; }
     88   goto exit;
     89 }
     90 
     91 void
     92 cache_ref_get(struct cache* cache)
     93 {
     94   ASSERT(cache);
     95   ref_get(&cache->ref);
     96 }
     97 
     98 void
     99 cache_ref_put(struct cache* cache)
    100 {
    101   ASSERT(cache);
    102   ref_put(&cache->ref, release_cache);
    103 }
    104 
    105 res_T
    106 cache_get_line
    107   (struct cache* cache,
    108    const size_t line_id,
    109    struct line* line)
    110 {
    111   const size_t chunk_id = line_id / NLINES_PER_CHUNK;
    112   const size_t chunk_line_id = line_id % NLINES_PER_CHUNK;
    113   res_T res = RES_OK;
    114 
    115   ASSERT(cache && line);
    116   ASSERT(chunk_id != CHUNK_ID_NONE && chunk_line_id < NLINES_PER_CHUNK);
    117 
    118   mutex_lock(cache->mutex);
    119   if(cache->chunk_id != chunk_id) {
    120     res = RES_BAD_ARG;
    121   } else {
    122     *line = cache->lines[chunk_line_id];
    123   }
    124   mutex_unlock(cache->mutex);
    125 
    126   return res;
    127 }
    128 
    129 void
    130 cache_put_chunk
    131   (struct cache* cache,
    132    const size_t chunk_id,
    133    const struct line lines[NLINES_PER_CHUNK])
    134 {
    135   ASSERT(cache && chunk_id != CHUNK_ID_NONE && lines);
    136 
    137   mutex_lock(cache->mutex);
    138   if(cache->chunk_id != chunk_id) {
    139     cache->chunk_id = chunk_id;
    140     memcpy(cache->lines, lines, sizeof(struct line)*NLINES_PER_CHUNK);
    141   }
    142   mutex_unlock(cache->mutex);
    143 }