X-Git-Url: http://git.vrable.net/?a=blobdiff_plain;f=bluesky%2Fcache.c;h=c27d39dbdcd8dfc9c73f3ac9c7ac6caa8b5ab931;hb=6955b27db8185d222adb07e57d207f7f421037e6;hp=f8977731ba15ad45fd09247ce1c201df37f45e3f;hpb=870ff381b99c54615457d1cea92e710bc68e194b;p=bluesky.git

diff --git a/bluesky/cache.c b/bluesky/cache.c
index f897773..c27d39d 100644
--- a/bluesky/cache.c
+++ b/bluesky/cache.c
@@ -101,15 +101,22 @@ static void flushd_dirty(BlueSkyFS *fs)
     g_mutex_unlock(fs->lock);
 }
 
-/* Try to flush dirty data to the cloud.
- * TODO: Rewrite this to work on cloud log items rather than inodes, so we can
- * better track which logs are fully synchronized to the cloud and can be
- * garbage collected if needed? */
+/* Try to flush dirty data to the cloud.  This will take a snapshot of the
+ * entire filesystem (though only point-in-time consistent for isolated inodes
+ * and not the filesystem as a whole) and ensure all data is written to the
+ * cloud.  When the write completes, we will allow old journal segments (those
+ * that were fully written _before_ the snapshot process started) to be garbage
+ * collected.  Newer journal segments can't be collected yet since they may
+ * still contain data which has not been written persistently to the cloud. */
 static void flushd_cloud(BlueSkyFS *fs)
 {
-    int64_t start_time = bluesky_get_current_time();
     g_mutex_lock(fs->lock);
 
+    /* TODO: Locking?  Since we're reading a single variable this is probably
+     * atomic but a lock could be safer. */
+    BlueSkyCloudLog *marker = bluesky_log_get_commit_point(fs);
+    int journal_seq_start = fs->log->seq_num;
+
     while (1) {
         BlueSkyInode *inode;
         if (fs->dirty_list.prev == NULL)
@@ -121,29 +128,19 @@ static void flushd_cloud(BlueSkyFS *fs)
                   "Flushing inode %"PRIu64" to cloud", 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
-         * out. */
-        uint64_t elapsed = bluesky_get_current_time() - inode->change_time;
-        if (g_atomic_int_get(&fs->cache_dirty) < bluesky_watermark_low_dirty
-                && elapsed < WRITEBACK_DELAY)
-            break;
-        if (inode->change_time > start_time)
-            break;
-
         bluesky_inode_ref(inode);
 
         g_mutex_unlock(fs->lock);
 
         g_mutex_lock(inode->lock);
-        flushd_dirty_inode(inode);
+        g_assert(inode->change_cloud == inode->change_commit);
         g_mutex_lock(fs->lock);
         bluesky_list_unlink(&fs->dirty_list, inode->dirty_list);
         inode->dirty_list = NULL;
         g_mutex_unlock(fs->lock);
 
         BlueSkyCloudLog *log = inode->committed_item;
-        bluesky_cloudlog_ref(log);
+        inode->committed_item = NULL;
         g_mutex_unlock(inode->lock);
 
         if (log != NULL)
@@ -154,8 +151,39 @@ static void flushd_cloud(BlueSkyFS *fs)
         g_mutex_lock(fs->lock);
     }
 
+    /* Write out any updated inode map entries, so that all inodes just written
+     * can be located, and then a final commit record. */
+    BlueSkyCloudLog *commit_record = bluesky_inode_map_serialize(fs);
+    bluesky_cloudlog_serialize(commit_record, fs);
+
     g_mutex_unlock(fs->lock);
     bluesky_cloudlog_flush(fs);
+
+    /* Wait until all segments have been written to the cloud, so that it
+     * becomes safe to free up journal segments. */
+    while (fs->log_state->pending_segments != NULL) {
+        SerializedRecord *segment
+            = (SerializedRecord *)fs->log_state->pending_segments->data;
+        g_mutex_lock(segment->lock);
+        while (!segment->complete)
+            g_cond_wait(segment->cond, segment->lock);
+        g_mutex_unlock(segment->lock);
+
+        g_mutex_free(segment->lock);
+        g_cond_free(segment->cond);
+        g_free(segment);
+
+        fs->log_state->pending_segments
+            = g_list_delete_link(fs->log_state->pending_segments,
+                                 fs->log_state->pending_segments);
+    }
+
+    bluesky_log_write_commit_point(fs, marker);
+
+    g_print("All segments have been flushed, journal < %d is clean\n",
+            journal_seq_start);
+
+    fs->log->journal_watermark = journal_seq_start;
 }
 
 /* Drop cached data for a given inode, if it is clean.  inode must be locked. */
@@ -243,6 +271,7 @@ static gpointer flushd_task(BlueSkyFS *fs)
     flushd_dirty(fs);
     flushd_cloud(fs);
     flushd_clean(fs);
+    bluesky_cachefile_gc(fs);
     g_mutex_unlock(fs->flushd_lock);
 
     return NULL;