+ while (log_items != NULL) {
+ BlueSkyCloudLog *item = (BlueSkyCloudLog *)log_items->data;
+
+ g_mutex_lock(item->lock);
+ while ((item->pending_write & CLOUDLOG_JOURNAL))
+ g_cond_wait(item->cond, item->lock);
+ g_mutex_unlock(item->lock);
+ bluesky_cloudlog_unref(item);
+
+ log_items = g_list_delete_link(log_items, log_items);
+ }
+}
+
+/* Memory-map the given log object into memory (read-only) and return a pointer
+ * to it. */
+static int page_size = 0;
+
+void bluesky_cachefile_unref(BlueSkyCacheFile *cachefile)
+{
+ g_atomic_int_add(&cachefile->refcount, -1);
+}
+
+static void cloudlog_fetch_complete(BlueSkyStoreAsync *async,
+ BlueSkyCacheFile *cachefile)
+{
+ g_print("Fetch of %s from cloud complete, status = %d\n",
+ async->key, async->result);
+
+ if (async->result < 0)
+ return;
+
+ g_mutex_lock(cachefile->lock);
+ char *pathname = g_strdup_printf("%s/%s", cachefile->log->log_directory,
+ cachefile->filename);
+ if (!g_file_set_contents(pathname, async->data->data, async->data->len,
+ NULL))
+ {
+ g_print("Error writing out fetched file to cache!\n");
+ }
+ g_free(pathname);
+ cachefile->fetching = FALSE;
+ cachefile->ready = TRUE;
+ bluesky_cachefile_unref(cachefile);
+ g_cond_broadcast(cachefile->cond);
+ g_mutex_unlock(cachefile->lock);
+}
+
+/* Find the BlueSkyCacheFile object for the given journal or cloud log segment.
+ * Returns the object in the locked state and with a reference taken. */
+BlueSkyCacheFile *bluesky_cachefile_lookup(BlueSkyFS *fs,
+ int clouddir, int log_seq)
+{
+ if (page_size == 0) {
+ page_size = getpagesize();
+ }
+
+ BlueSkyLog *log = fs->log;
+
+ char logname[64];
+ int type;
+
+ // A request for a local log file
+ if (clouddir < 0) {
+ sprintf(logname, "journal-%08d", log_seq);
+ type = CLOUDLOG_JOURNAL;
+ } else {
+ sprintf(logname, "log-%08d-%08d", clouddir, log_seq);
+ type = CLOUDLOG_CLOUD;
+ }
+
+ BlueSkyCacheFile *map;
+ g_mutex_lock(log->mmap_lock);
+ map = g_hash_table_lookup(log->mmap_cache, logname);
+
+ if (map == NULL) {
+ /* TODO: stat() call */
+ map = g_new0(BlueSkyCacheFile, 1);
+ map->type = CLOUDLOG_JOURNAL;
+ map->lock = g_mutex_new();
+ map->type = type;
+ g_mutex_lock(map->lock);
+ map->cond = g_cond_new();
+ map->filename = g_strdup(logname);
+ map->log_seq = log_seq;
+ map->log = log;
+ g_atomic_int_set(&map->mapcount, 0);
+ g_atomic_int_set(&map->refcount, 0);
+
+ g_hash_table_insert(log->mmap_cache, map->filename, map);
+
+ // If the log file is stored in the cloud, we may need to fetch it
+ if (clouddir >= 0) {
+ g_atomic_int_inc(&map->refcount);
+ map->fetching = TRUE;
+ g_print("Starting fetch of %s from cloud\n", logname);
+ BlueSkyStoreAsync *async = bluesky_store_async_new(fs->store);
+ async->op = STORE_OP_GET;
+ async->key = g_strdup(logname);
+ bluesky_store_async_add_notifier(async,
+ (GFunc)cloudlog_fetch_complete,
+ map);
+ bluesky_store_async_submit(async);
+ bluesky_store_async_unref(async);
+ }
+ } else {
+ g_mutex_lock(map->lock);
+ }
+
+ g_mutex_unlock(log->mmap_lock);
+ g_atomic_int_inc(&map->refcount);
+ return map;
+}
+
+BlueSkyRCStr *bluesky_log_map_object(BlueSkyFS *fs, int log_dir,
+ int log_seq, int log_offset, int log_size)
+{
+ if (page_size == 0) {
+ page_size = getpagesize();
+ }
+
+ BlueSkyLog *log = fs->log;
+ BlueSkyCacheFile *map = bluesky_cachefile_lookup(fs, log_dir, log_seq);
+
+ if (map == NULL) {
+ return NULL;
+ }
+
+ if (map->addr == NULL) {
+ while (!map->ready && map->fetching) {
+ g_print("Waiting for log segment to be fetched from cloud...\n");
+ g_cond_wait(map->cond, map->lock);
+ }
+
+ int fd = openat(log->dirfd, map->filename, O_RDONLY);
+
+ if (fd < 0) {
+ fprintf(stderr, "Error opening logfile %s: %m\n", map->filename);
+ bluesky_cachefile_unref(map);
+ g_mutex_unlock(map->lock);
+ return NULL;
+ }
+
+ off_t length = lseek(fd, 0, SEEK_END);
+ map->addr = (const char *)mmap(NULL, length, PROT_READ, MAP_SHARED,
+ fd, 0);
+ g_atomic_int_add(&log->disk_used, -(map->len / 1024));
+ map->len = length;
+ g_atomic_int_add(&log->disk_used, map->len / 1024);
+
+ g_print("Re-mapped log segment %d...\n", log_seq);
+ g_atomic_int_inc(&map->refcount);
+
+ close(fd);
+ }
+
+ g_mutex_unlock(log->mmap_lock);
+
+ BlueSkyRCStr *str;
+ map->atime = bluesky_get_current_time();
+ str = bluesky_string_new_from_mmap(map, log_offset, log_size);
+ bluesky_cachefile_unref(map);
+ g_mutex_unlock(map->lock);
+ return str;