Add LRU lists for tracking inodes that are dirty/accessed.

[bluesky.git] / bluesky / bluesky.h

diff --git a/bluesky/bluesky.h b/bluesky/bluesky.h
index e30f5b0..59a33c5 100644 (file)
--- a/bluesky/bluesky.h
+++ b/bluesky/bluesky.h
@@ -37,6 +37,10 @@ typedef struct {
 
 extern BlueSkyOptions bluesky_options;
 
+/* Maximum number of threads to use in any particular thread pool, or -1 for no
+ * limit */
+extern int bluesky_max_threads;
+
 /* BlueSky status and error codes.  Various frontends should translate these to
  * the appropriate error code for whatever protocol they implement. */
 typedef enum {
@@ -112,6 +116,19 @@ typedef struct {
     uint64_t next_inum;         /* Next available inode for allocation */
 
     BlueSkyStore *store;
+
+    /* Accounting for memory used for caches.  Space is measured in blocks, not
+     * bytes.  We track both total data in the caches and dirty data (total
+     * data includes dirty data).  Updates to these variables must be made
+     * atomically. */
+    gint cache_total, cache_dirty;
+
+    /* Linked list of inodes, sorted by access/modification times for cache
+     * management.  Editing these lists is protected by the filesystem lock; to
+     * avoid deadlock do not attempt to take any other locks while the FS lock
+     * is held for list editing purposes.  Items at the head of the list are
+     * most recently accessed/modified. */
+    GList dirty_list, accessed_list;
 } BlueSkyFS;
 
 /* Inode number of the root directory. */
@@ -175,6 +192,12 @@ typedef struct {
     /* Additional state for tracking cache writeback status. */
     uint64_t change_pending;    /* change_count version currently being committed to storage */
 
+    /* Pointers to the linked-list elements for this inode in the accessed and
+     * dirty linked lists.  We re-use the GList structure, using ->next to
+     * point to the head of the list and ->prev to point to the tail.  The data
+     * element is unused. */
+    GList *accessed_list, *dirty_list;
+
     int64_t atime;              /* Microseconds since the Unix epoch */
     int64_t ctime;
     int64_t mtime;