Function bcache_write

src/blockcache.cc:1026–1145

}

int bcache_write(struct filemgr *file,
                 bid_t bid,
                 void *buf,
                 bcache_dirty_t dirty,
                 bool final_write)
{
    struct hash_elem *h = NULL;
    struct bcache_item *item;
    struct bcache_item query;
    struct fnamedic_item *fname_new;

    fname_new = file->bcache;
    if (fname_new == NULL) {
        spin_lock(&bcache_lock);
        fname_new = file->bcache;
        if (fname_new == NULL) {
            // filename doesn't exist in filename dictionary .. create
            fname_new = _fname_create(file);
        }
        spin_unlock(&bcache_lock);
    }

    // Update the access timestamp.
    struct timeval tp;
    gettimeofday(&tp, NULL);
    atomic_store_uint64_t(&fname_new->access_timestamp,
                          (uint64_t) (tp.tv_sec * 1000000 + tp.tv_usec));

    size_t shard_num = bid % fname_new->num_shards;
    // set query
    query.bid = bid;

    spin_lock(&fname_new->shards[shard_num].lock);

    // search hash table
    h = hash_find(&fname_new->shards[shard_num].hashtable, &query.hash_elem);
    if (h == NULL) {
        // cache miss
        // get a free block
        while ((item = _bcache_alloc_freeblock()) == NULL) {
            // no free block .. perform eviction
            spin_unlock(&fname_new->shards[shard_num].lock);

            _bcache_evict(fname_new);

            spin_lock(&fname_new->shards[shard_num].lock);
        }

        // re-search hash table
        h = hash_find(&fname_new->shards[shard_num].hashtable, &query.hash_elem);
        if (h == NULL) {
            // insert into hash table
            item->bid = bid;
            item->flag = BCACHE_FREE;
            hash_insert(&fname_new->shards[shard_num].hashtable, &item->hash_elem);
            h = &item->hash_elem;
        } else {
            // insert into freelist again