Implement a (dumb) cache garbage collector.

[bluesky.git] / bluesky / bluesky-private.h

diff --git a/bluesky/bluesky-private.h b/bluesky/bluesky-private.h
index 0f86f45..73f38e1 100644 (file)
--- a/bluesky/bluesky-private.h
+++ b/bluesky/bluesky-private.h
@@ -44,7 +44,7 @@ BlueSkyInode *bluesky_list_tail(GList *head);
  * persistent storage. */
 void bluesky_serialize_superblock(GString *out, BlueSkyFS *fs);
 BlueSkyFS *bluesky_deserialize_superblock(const gchar *buf);
-void bluesky_serialize_inode(GString *out, BlueSkyInode *inode);
+BlueSkyCloudLog *bluesky_serialize_inode(BlueSkyInode *inode);
 gboolean bluesky_deserialize_inode(BlueSkyInode *inode, const gchar *buf);
 
 /* Storage layer.  Requests can be performed asynchronously, so these objects
@@ -165,6 +165,7 @@ typedef struct {
 } BlueSkyCloudPointer;
 
 typedef enum {
+    LOGTYPE_INVALID = -1,
     LOGTYPE_UNKNOWN = 0,
     LOGTYPE_DATA = 1,
     LOGTYPE_INODE = 2,
@@ -206,11 +207,16 @@ struct _BlueSkyCloudLog {
     // TODO: Location in journal/cache
     int log_seq, log_offset, log_size;
 
-    // Pointers to other objects
-    GArray *pointers;
+    // Pointers to other objects.  Each link counts towards the reference count
+    // of the pointed-to object.  To avoid memory leaks there should be no
+    // cycles in the reference graph.
+    GArray *links;
 
-    // Serialized data, if available in memory (otherwise NULL).
+    // Serialized data, if available in memory (otherwise NULL), and a lock
+    // count which tracks if there are users that require the data to be kept
+    // around.
     BlueSkyRCStr *data;
+    int data_lock_count;
 };
 
 /* Serialize objects into a log segment to be written to the cloud. */
@@ -227,10 +233,13 @@ gchar *bluesky_cloudlog_id_to_string(BlueSkyCloudID id);
 BlueSkyCloudID bluesky_cloudlog_id_from_string(const gchar *idstr);
 void bluesky_cloudlog_ref(BlueSkyCloudLog *log);
 void bluesky_cloudlog_unref(BlueSkyCloudLog *log);
+void bluesky_cloudlog_stats_update(BlueSkyCloudLog *log, int type);
 void bluesky_cloudlog_sync(BlueSkyCloudLog *log);
 void bluesky_cloudlog_insert(BlueSkyCloudLog *log);
-void bluesky_cloudlog_write_log(BlueSkyFS *fs);
 void bluesky_cloudlog_fetch(BlueSkyCloudLog *log);
+BlueSkyCloudPointer bluesky_cloudlog_serialize(BlueSkyCloudLog *log,
+                                               BlueSkyFS *fs);
+void bluesky_cloudlog_flush(BlueSkyFS *fs);
 
 /* Logging infrastructure for ensuring operations are persistently recorded to
  * disk. */
@@ -248,25 +257,40 @@ struct _BlueSkyLog {
     /* Cache of log segments which have been memory-mapped. */
     GMutex *mmap_lock;
     GHashTable *mmap_cache;
+
+    /* A count of the disk space consumed (in 1024-byte units) by all files
+     * tracked by mmap_cache (whether mapped or not, actually). */
+    gint disk_used;
 };
 
-/* Reference-counted blocks of memory, used for passing data in and out of
- * storage backends and in other places.  This may also refer to read-only
- * mmaped data. */
-struct _BlueSkyMmap {
+/* An object for tracking log files which are stored locally--either the
+ * journal for filesystem consistency or log segments which have been fetched
+ * back from cloud storage. */
+struct _BlueSkyCacheFile {
+    GMutex *lock;
+    GCond *cond;
     gint refcount;
+    int type;                   // Only one of CLOUDLOG_{JOURNAL,CLOUD}
+    int log_dir;
     int log_seq;
-    const char *addr;
+    char *filename;             // Local filename, relateive to log directory
+    gint mapcount;              // References to the mmaped data
+    const char *addr;           // May be null if data is not mapped in memory
     size_t len;
+    BlueSkyFS *fs;
     BlueSkyLog *log;
+    gboolean fetching, ready;
+    int64_t atime;              // Access time, for cache management
 };
 
 BlueSkyLog *bluesky_log_new(const char *log_directory);
 void bluesky_log_item_submit(BlueSkyCloudLog *item, BlueSkyLog *log);
 void bluesky_log_finish_all(GList *log_items);
-BlueSkyRCStr *bluesky_log_map_object(BlueSkyLog *log, int log_seq,
+BlueSkyRCStr *bluesky_log_map_object(BlueSkyFS *fs, int log_dir, int log_seq,
                                      int log_offset, int log_size);
-void bluesky_mmap_unref(BlueSkyMmap *mmap);
+void bluesky_mmap_unref(BlueSkyCacheFile *mmap);
+
+void bluesky_cachefile_gc(BlueSkyFS *fs);
 
 #ifdef __cplusplus
 }