thodg/got/lib/delta_cache.c

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• Hash : c3b318d0
  Author :
  Date : 2019-11-10T15:51:05
  

  add debug stats to delta cache
  

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• lib/delta_cache.c

• /*
   * Copyright (c) 2019 Stefan Sperling <stsp@openbsd.org>
   *
   * Permission to use, copy, modify, and distribute this software for any
   * purpose with or without fee is hereby granted, provided that the above
   * copyright notice and this permission notice appear in all copies.
   *
   * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
   * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
   * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
   * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
   * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
   * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
   * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
   */
  
  #include <sys/queue.h>
  
  #include <stdlib.h>
  #include <string.h>
  #include <sha1.h>
  #include <stdio.h>
  #include <zlib.h>
  #include <limits.h>
  #include <time.h>
  
  #include "got_object.h"
  #include "got_error.h"
  
  #include "got_lib_delta.h"
  #include "got_lib_inflate.h"
  #include "got_lib_object.h"
  #include "got_lib_delta_cache.h"
  
  #ifndef nitems
  #define nitems(_a) (sizeof(_a) / sizeof((_a)[0]))
  #endif
  
  struct got_delta_cache_element {
  	TAILQ_ENTRY(got_delta_cache_element) entry;
  	off_t delta_data_offset;
  	uint8_t *delta_data;
  	size_t delta_len;
  };
  
  TAILQ_HEAD(got_delta_cache_head, got_delta_cache_element);
  
  struct got_delta_cache {
  	struct got_delta_cache_head entries;
  	int nelem;
  	int maxelem;
  	size_t maxelemsize;
  	int cache_search;
  	int cache_hit;
  	int cache_miss;
  	int cache_evict;
  	int cache_toolarge;
  };
  
  struct got_delta_cache *
  got_delta_cache_alloc(int maxelem, size_t maxelemsize)
  {
  	struct got_delta_cache *cache;
  
  	cache = calloc(1, sizeof(*cache));
  	if (cache == NULL)
  		return NULL;
  
  	TAILQ_INIT(&cache->entries);
  	cache->maxelem = maxelem;
  	cache->maxelemsize = maxelemsize;
  	return cache;
  }
  
  void
  got_delta_cache_free(struct got_delta_cache *cache)
  {
  	struct got_delta_cache_element *entry;
  
  #ifdef GOT_OBJ_CACHE_DEBUG
  	fprintf(stderr, "%s: delta cache: %d elements, %d searches, %d hits, "
  	    "%d missed, %d evicted, %d too large\n", getprogname(), cache->nelem,
  	    cache->cache_search, cache->cache_hit, cache->cache_miss,
  	    cache->cache_evict, cache->cache_toolarge);
  #endif
  	while (!TAILQ_EMPTY(&cache->entries)) {
  		entry = TAILQ_FIRST(&cache->entries);
  		TAILQ_REMOVE(&cache->entries, entry, entry);
  		free(entry->delta_data);
  		free(entry);
  	}
  	free(cache);
  }
  
  static void
  remove_least_used_element(struct got_delta_cache *cache)
  {
  	struct got_delta_cache_element *entry;
  
  	if (cache->nelem == 0)
  		return;
  
  	entry = TAILQ_LAST(&cache->entries, got_delta_cache_head);
  	TAILQ_REMOVE(&cache->entries, entry, entry);
  	free(entry->delta_data);
  	free(entry);
  	cache->nelem--;
  	cache->cache_evict++;
  }
  
  
  const struct got_error *
  got_delta_cache_add(struct got_delta_cache *cache,
      off_t delta_data_offset, uint8_t *delta_data, size_t delta_len)
  {
  	struct got_delta_cache_element *entry;
  
  	if (delta_len > cache->maxelemsize) {
  		cache->cache_toolarge++;
  		return got_error(GOT_ERR_NO_SPACE);
  	}
  
  	if (cache->nelem >= cache->maxelem)
  		remove_least_used_element(cache);
  
  	entry = calloc(1, sizeof(*entry));
  	if (entry == NULL)
  		return got_error_from_errno("calloc");
  
  	entry->delta_data_offset = delta_data_offset;
  	entry->delta_data = delta_data;
  	entry->delta_len = delta_len;
  
  	TAILQ_INSERT_HEAD(&cache->entries, entry, entry);
  	cache->nelem++;
  	return NULL;
  }
  
  void
  got_delta_cache_get(uint8_t **delta_data, size_t *delta_len,
      struct got_delta_cache *cache, off_t delta_data_offset)
  {
  	struct got_delta_cache_element *entry;
  
  	cache->cache_search++;
  	*delta_data = NULL;
  	*delta_len = 0;
  	TAILQ_FOREACH(entry, &cache->entries, entry) {
  		if (entry->delta_data_offset != delta_data_offset)
  			continue;
  		cache->cache_hit++;
  		if (entry != TAILQ_FIRST(&cache->entries)) {
  			TAILQ_REMOVE(&cache->entries, entry, entry);
  			TAILQ_INSERT_HEAD(&cache->entries, entry, entry);
  		}
  		*delta_data = entry->delta_data;
  		*delta_len = entry->delta_len;
  		return;
  	}
  
  	cache->cache_miss++;
  }
  

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