file_cache_entry_t* file_cache_put(const char* file_path) {
static size_t file_cache_head = 0;
int file_fd = -1;
off_t file_len;
char* file_buf = NULL;
int nbytes;
file_cache_entry_t* old_entry = NULL;
// Allocate a new entry
file_cache_entry_t* new_entry = (file_cache_entry_t*)
malloc(sizeof(*new_entry));
if (new_entry == NULL) goto exit; // out of memory
// Copy the file path
new_entry->file_path = strdup(file_path);
if (new_entry->file_path == NULL) goto exit; // out of memory
// Open the file
file_fd= open(file_path, O_RDONLY);
if (file_fd < 0) goto exit;
// Determine the length of the file
file_len = lseek(file_fd, (off_t)0, SEEK_END);
file_buf = new_entry->data.buf = (char*) malloc(file_len);
if (file_buf == NULL) goto exit;
new_entry->data.len = file_len;
// Cache the content of the file
lseek(file_fd, (off_t)0, SEEK_SET);
while ((nbytes = read(file_fd, file_buf, file_len)) > 0) {
file_buf += nbytes;
file_len -= nbytes;
}
if (nbytes < 0) goto exit;
// Put the new entry in the cache
old_entry = file_cache[file_cache_head];
if (old_entry != NULL) file_cache_evict(old_entry);
file_cache[file_cache_head++] = new_entry;
if (file_cache_head == MAX_CACHED_FILES) file_cache_head = 0;
close(file_fd);
return new_entry;
exit:
if (file_fd >= 0) close(file_fd);
free(file_buf);
if (new_entry) free(new_entry->file_path);
free(new_entry);
return NULL;
}
int main()
{
printf("Simple File Caching!\n");
char *file[] = {"file1", "file2", "file3", "file4"};
file_cache *cache = file_cache_construct(4);
file_cache_pin_files(cache, (const char **)file, 3);
file_cache_unpin_files(cache, (const char **) file, 2);
file_cache_evict(cache);
printf("Destroying cache!\n");
file_cache_destroy(cache);
return 0;
}