X-Git-Url: http://git.vrable.net/?a=blobdiff_plain;f=bluesky%2Fcache.c;h=d8ef5faba32cd9f2a8f41c5c486e1de339f09ee0;hb=0ca475013b6d6da3fa520001f6f6a50cab482299;hp=b05baf8f5fe0e4d5f5677541864c0c52f5f8475a;hpb=c576372ed59370ff97a3bf2353ab477e4b744fac;p=bluesky.git

diff --git a/bluesky/cache.c b/bluesky/cache.c
index b05baf8..d8ef5fa 100644
--- a/bluesky/cache.c
+++ b/bluesky/cache.c
@@ -6,10 +6,20 @@
  * TODO: Licensing
  */
 
+#define _GNU_SOURCE
+#define _ATFILE_SOURCE
+
+#include <stdio.h>
 #include <stdint.h>
+#include <stdlib.h>
 #include <glib.h>
 #include <string.h>
+#include <errno.h>
 #include <inttypes.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
 
 #include "bluesky-private.h"
 
@@ -272,6 +282,98 @@ static void flushd_clean(BlueSkyFS *fs)
     g_mutex_unlock(fs->lock);
 }
 
+/* Scan through all currently-stored files in the journal/cache and garbage
+ * collect old unused ones, if needed. */
+static void gather_cachefiles(gpointer key, gpointer value, gpointer user_data)
+{
+    GList **files = (GList **)user_data;
+    *files = g_list_prepend(*files, value);
+}
+
+static gint compare_cachefiles(gconstpointer a, gconstpointer b)
+{
+    int64_t ta, tb;
+
+    ta = ((BlueSkyCacheFile *)a)->atime;
+    tb = ((BlueSkyCacheFile *)b)->atime;
+    if (ta < tb)
+        return -1;
+    else if (ta > tb)
+        return 1;
+    else
+        return 0;
+}
+
+void bluesky_cachefile_gc(BlueSkyFS *fs)
+{
+    GList *files = NULL;
+
+    g_mutex_lock(fs->log->mmap_lock);
+    g_hash_table_foreach(fs->log->mmap_cache, gather_cachefiles, &files);
+
+    /* Sort based on atime.  The atime should be stable since it shouln't be
+     * updated except by threads which can grab the mmap_lock, which we already
+     * hold. */
+    files = g_list_sort(files, compare_cachefiles);
+
+    /* Walk the list of files, starting with the oldest, deleting files if
+     * possible until enough space has been reclaimed. */
+    g_print("\nScanning cache: (total size = %d kB)\n", fs->log->disk_used);
+    while (files != NULL) {
+        BlueSkyCacheFile *cachefile = (BlueSkyCacheFile *)files->data;
+        /* Try to lock the structure, but if the lock is held by another thread
+         * then we'll just skip the file on this pass. */
+        if (g_mutex_trylock(cachefile->lock)) {
+            int64_t age = bluesky_get_current_time() - cachefile->atime;
+            g_print("%s addr=%p mapcount=%d refcount=%d atime_age=%f",
+                    cachefile->filename, cachefile->addr, cachefile->mapcount,
+                    cachefile->refcount, age / 1e6);
+            if (cachefile->fetching)
+                g_print(" (fetching)");
+            g_print("\n");
+
+            gboolean deletion_candidate = FALSE;
+            if (g_atomic_int_get(&fs->log->disk_used)
+                    > bluesky_options.cache_size
+                && g_atomic_int_get(&cachefile->refcount) == 0
+                && g_atomic_int_get(&cachefile->mapcount) == 0)
+            {
+                deletion_candidate = TRUE;
+            }
+
+            /* Don't allow journal files to be reclaimed until all data is
+             * known to be durably stored in the cloud. */
+            if (cachefile->type == CLOUDLOG_JOURNAL
+                && cachefile->log_seq >= fs->log->journal_watermark)
+            {
+                deletion_candidate = FALSE;
+            }
+
+            if (deletion_candidate) {
+                g_print("   ...deleting\n");
+                if (unlinkat(fs->log->dirfd, cachefile->filename, 0) < 0) {
+                    fprintf(stderr, "Unable to unlink journal %s: %m\n",
+                            cachefile->filename);
+                }
+
+                g_atomic_int_add(&fs->log->disk_used, -(cachefile->len / 1024));
+                g_hash_table_remove(fs->log->mmap_cache, cachefile->filename);
+                g_mutex_unlock(cachefile->lock);
+                g_mutex_free(cachefile->lock);
+                g_cond_free(cachefile->cond);
+                g_free(cachefile->filename);
+                g_free(cachefile);
+            } else {
+                g_mutex_unlock(cachefile->lock);
+            }
+        }
+        files = g_list_delete_link(files, files);
+    }
+    g_list_free(files);
+
+    g_mutex_unlock(fs->log->mmap_lock);
+}
+
 /* Run the flush daemon for a single iteration, though if it is already
  * executing returns immediately. */
 static gpointer flushd_task(BlueSkyFS *fs)