#define WRITEBACK_DELAY (20 * 1000000)
-/* Filesystem caching and cache coherency. */
+/* Filesystem caching and cache coherency. There are actually a couple of
+ * different tasks that are performed here:
+ * - Forcing data to the log if needed to reclaim memory or simply if the
+ * data has been dirty in memory long enough.
+ * - Writing batches of data to the cloud.
+ */
+#if 0
static void writeback_complete(gpointer a, gpointer i)
{
BlueSkyInode *inode = (BlueSkyInode *)i;
- g_log("bluesky/flushd", G_LOG_LEVEL_DEBUG,
- "Writeback for inode %"PRIu64" complete", inode->inum);
+ if (bluesky_verbose) {
+ g_log("bluesky/flushd", G_LOG_LEVEL_DEBUG,
+ "Writeback for inode %"PRIu64" complete", inode->inum);
+ }
g_mutex_lock(inode->lock);
g_mutex_unlock(inode->lock);
}
-
-#if 0
-static void flushd_inode(gpointer value, gpointer user_data)
-{
- BlueSkyFS *fs = (BlueSkyFS *)user_data;
-
- BlueSkyInode *inode = (BlueSkyInode *)value;
-
- g_mutex_lock(inode->lock);
-
- if (inode->change_count == inode->change_commit) {
- uint64_t delay = bluesky_get_current_time() - inode->access_time;
- if (delay >= CACHE_CLEAN_DELAY) {
- drop_caches(inode);
-
- /* If the only references are the one we hold and the one in the
- * filesystem inum->inode hash table... First check the refcount
- * without the lock for speed, but if the check looks good verify
- * it after taking the filesystem lock. */
- if (inode->refcount == 2) {
- g_mutex_lock(fs->lock);
- if (inode->refcount == 2) {
- g_log("bluesky/flushd", G_LOG_LEVEL_DEBUG,
- "Trying to drop inode %"PRIu64" from cache",
- inode->inum);
- if (g_hash_table_remove(fs->inodes, &inode->inum))
- bluesky_inode_unref(inode);
- }
- bluesky_list_unlink(&inode->fs->accessed_list,
- inode->accessed_list);
- inode->accessed_list = NULL;
- bluesky_list_unlink(&inode->fs->dirty_list,
- inode->dirty_list);
- inode->dirty_list = NULL;
- g_mutex_unlock(fs->lock);
- }
- }
-
- g_mutex_unlock(inode->lock);
- bluesky_inode_unref(inode);
- return;
- }
-
- if (inode->change_pending) {
- /* Waiting for an earlier writeback to finish, so don't start a new
- * writeback yet. */
- g_mutex_unlock(inode->lock);
- bluesky_inode_unref(inode);
- return;
- }
-
- uint64_t elapsed = bluesky_get_current_time() - inode->change_time;
- if (elapsed < WRITEBACK_DELAY) {
- /* Give a bit more time before starting writeback. */
- g_mutex_unlock(inode->lock);
- bluesky_inode_unref(inode);
- return;
- }
-
- inode->change_pending = inode->change_count;
-
- g_log("bluesky/flushd", G_LOG_LEVEL_DEBUG,
- "Starting flush of inode %"PRIu64, inode->inum);
-
- /* Create a store barrier. All operations part of the writeback will be
- * added to this barrier, so when the barrier completes we know that the
- * writeback is finished. */
- BlueSkyStoreAsync *barrier = bluesky_store_async_new(fs->store);
- barrier->op = STORE_OP_BARRIER;
-
- bluesky_inode_start_sync(inode, barrier);
-
- bluesky_store_async_add_notifier(barrier, writeback_complete, inode);
- bluesky_store_async_submit(barrier);
- bluesky_store_async_unref(barrier);
-
- g_mutex_unlock(inode->lock);
- bluesky_inode_unref(inode);
-}
#endif
static void flushd_dirty_inode(BlueSkyInode *inode)
{
BlueSkyFS *fs = inode->fs;
+ g_mutex_lock(fs->lock);
+ bluesky_list_unlink(&fs->dirty_list, inode->dirty_list);
+ inode->dirty_list = NULL;
+ g_mutex_unlock(fs->lock);
+
/* Inode is clean; nothing to do. */
if (inode->change_count == inode->change_commit)
return;
- /* Inode writeback is in progress; put back on the dirty list. */
- if (inode->change_pending) {
- /* Waiting for an earlier writeback to finish, so don't start a new
- * writeback yet. */
- g_mutex_lock(fs->lock);
- inode->change_time = bluesky_get_current_time();
- bluesky_list_unlink(&fs->dirty_list, inode->dirty_list);
- inode->dirty_list = bluesky_list_prepend(&fs->dirty_list, inode);
- g_mutex_unlock(fs->lock);
- return;
+ if (bluesky_verbose) {
+ g_log("bluesky/flushd", G_LOG_LEVEL_DEBUG,
+ "Starting flush of inode %"PRIu64, inode->inum);
}
- g_log("bluesky/flushd", G_LOG_LEVEL_DEBUG,
- "Starting flush of inode %"PRIu64, inode->inum);
- inode->change_pending = inode->change_count;
-
- /* Create a store barrier. All operations part of the writeback will be
- * added to this barrier, so when the barrier completes we know that the
- * writeback is finished. */
- BlueSkyStoreAsync *barrier = bluesky_store_async_new(fs->store);
- barrier->op = STORE_OP_BARRIER;
-
- bluesky_inode_start_sync(inode, barrier);
-
- bluesky_store_async_add_notifier(barrier, writeback_complete, inode);
- bluesky_store_async_submit(barrier);
- bluesky_store_async_unref(barrier);
+ bluesky_inode_start_sync(inode);
}
/* Try to flush dirty data to disk, either due to memory pressure or due to
break;
inode = fs->dirty_list.prev->data;
- g_print("Considering flushing inode %"PRIu64"\n", inode->inum);
+ if (bluesky_verbose) {
+ g_log("bluesky/flushd", G_LOG_LEVEL_DEBUG,
+ "Considering flushing inode %"PRIu64, inode->inum);
+ }
/* Stop processing dirty inodes if we both have enough memory available
* and the oldest inode is sufficiently new that it need not be flushed
bluesky_inode_ref(inode);
- bluesky_list_unlink(&fs->dirty_list, fs->dirty_list.prev);
- inode->dirty_list = NULL;
-
g_mutex_unlock(fs->lock);
g_mutex_lock(inode->lock);
bluesky_file_drop_cached(inode);
}
-/* Drop clean data fromt the cache if needed due to memory pressure. */
+/* Drop clean data from the cache if needed due to memory pressure. */
static void flushd_clean(BlueSkyFS *fs)
{
g_mutex_lock(fs->lock);
inode_count = 1;
while (inode_count-- > 0) {
+#if 0
if (g_atomic_int_get(&fs->cache_total) < bluesky_watermark_medium_total)
break;
+#endif
BlueSkyInode *inode;
if (fs->accessed_list.prev == NULL)
break;
inode = fs->accessed_list.prev->data;
- g_print("Considering dropping cached data for inode %"PRIu64"\n",
- inode->inum);
+ if (bluesky_verbose) {
+ g_log("bluesky/flushd", G_LOG_LEVEL_DEBUG,
+ "Considering dropping cached data for inode %"PRIu64,
+ inode->inum);
+ }
bluesky_inode_ref(inode);
- bluesky_list_unlink(&fs->accessed_list, fs->accessed_list.prev);
- inode->accessed_list = bluesky_list_prepend(&fs->accessed_list, inode);
-
g_mutex_unlock(fs->lock);
g_mutex_lock(inode->lock);
+
+ g_mutex_lock(fs->lock);
+ bluesky_list_unlink(&fs->accessed_list, inode->accessed_list);
+ inode->accessed_list = bluesky_list_prepend(&fs->accessed_list, inode);
+ g_mutex_unlock(fs->lock);
+
drop_caches(inode);
+
g_mutex_unlock(inode->lock);
bluesky_inode_unref(inode);
if (!g_mutex_trylock(fs->flushd_lock))
return NULL;
flushd_dirty(fs);
+ bluesky_cloudlog_write_log(fs);
flushd_clean(fs);
g_mutex_unlock(fs->flushd_lock);
&& g_atomic_int_get(&fs->cache_total) < bluesky_watermark_high_total)
return;
- g_log("bluesky/flushd", G_LOG_LEVEL_DEBUG,
- "Too much data; invoking flushd: dirty=%d total=%d",
- g_atomic_int_get(&fs->cache_dirty),
- g_atomic_int_get(&fs->cache_total));
+ if (bluesky_verbose) {
+ g_log("bluesky/flushd", G_LOG_LEVEL_DEBUG,
+ "Too much data; invoking flushd: dirty=%d total=%d",
+ g_atomic_int_get(&fs->cache_dirty),
+ g_atomic_int_get(&fs->cache_total));
+ }
bluesky_flushd_invoke(fs);
}
+
+/* Start a perpetually-running thread that flushes the cache occasionally. */
+static gpointer flushd_thread(BlueSkyFS *fs)
+{
+ while (TRUE) {
+ bluesky_flushd_invoke(fs);
+ struct timespec delay;
+ delay.tv_sec = 2;
+ delay.tv_nsec = 0;
+ nanosleep(&delay, NULL);
+ }
+
+ return NULL;
+}
+
+void bluesky_flushd_thread_launch(BlueSkyFS *fs)
+{
+ g_thread_create((GThreadFunc)flushd_thread, fs, FALSE, NULL);
+}