X-Git-Url: http://git.vrable.net/?a=blobdiff_plain;f=bluesky%2Flog.c;h=66b4edb9131da2ad5151ae0af83158b49ca3aa64;hb=b8885660a453f0f1f30c9fed196b01a397482a19;hp=bdf14ffa08ad403ae0a541bd4e8028c039e4f389;hpb=f939d76d54717f98ac2f49f834d8deaab8e5596d;p=bluesky.git

diff --git a/bluesky/log.c b/bluesky/log.c
index bdf14ff..66b4edb 100644
--- a/bluesky/log.c
+++ b/bluesky/log.c
@@ -103,6 +103,11 @@ static gboolean log_open(BlueSkyLog *log)
         log->fd = -1;
     }
 
+    if (log->current_log != NULL) {
+        bluesky_cachefile_unref(log->current_log);
+        log->current_log = NULL;
+    }
+
     while (log->fd < 0) {
         g_snprintf(logname, sizeof(logname), "journal-%08d", log->seq_num);
         log->fd = openat(log->dirfd, logname, O_CREAT|O_WRONLY|O_EXCL, 0600);
@@ -116,6 +121,10 @@ static gboolean log_open(BlueSkyLog *log)
         }
     }
 
+    log->current_log = bluesky_cachefile_lookup(log->fs, -1, log->seq_num);
+    g_assert(log->current_log != NULL);
+    g_mutex_unlock(log->current_log->lock);
+
     if (ftruncate(log->fd, LOG_SEGMENT_SIZE) < 0) {
         fprintf(stderr, "Unable to truncate logfile %s: %m\n", logname);
     }
@@ -204,6 +213,13 @@ static gpointer log_thread(gpointer d)
 
         offset += sizeof(header) + sizeof(footer) + item->data->len;
 
+        /* Since we have just written a new dirty object to the journal,
+         * increment the count of live dirty objects in that journal file.  The
+         * count will be decremented when objects are deleted or written to the
+         * cloud. */
+        g_atomic_int_add(&log->current_log->dirty_refs, 1);
+        item->dirty_journal = log->current_log;
+
         /* Replace the log item's string data with a memory-mapped copy of the
          * data, now that it has been written to the log file.  (Even if it
          * isn't yet on disk, it should at least be in the page cache and so
@@ -234,7 +250,7 @@ BlueSkyLog *bluesky_log_new(const char *log_directory)
     log->seq_num = 0;
     log->queue = g_async_queue_new();
     log->mmap_lock = g_mutex_new();
-    log->mmap_cache = g_hash_table_new(NULL, NULL);
+    log->mmap_cache = g_hash_table_new(g_str_hash, g_str_equal);
 
     log->dirfd = open(log->log_directory, O_DIRECTORY);
     if (log->dirfd < 0) {
@@ -273,6 +289,11 @@ void bluesky_log_finish_all(GList *log_items)
  * to it. */
 static int page_size = 0;
 
+void bluesky_cachefile_unref(BlueSkyCacheFile *cachefile)
+{
+    g_atomic_int_add(&cachefile->refcount, -1);
+}
+
 static void cloudlog_fetch_complete(BlueSkyStoreAsync *async,
                                     BlueSkyCacheFile *cachefile)
 {
@@ -293,14 +314,15 @@ static void cloudlog_fetch_complete(BlueSkyStoreAsync *async,
     g_free(pathname);
     cachefile->fetching = FALSE;
     cachefile->ready = TRUE;
+    bluesky_cachefile_unref(cachefile);
     g_cond_broadcast(cachefile->cond);
     g_mutex_unlock(cachefile->lock);
 }
 
 /* Find the BlueSkyCacheFile object for the given journal or cloud log segment.
- * Returns the object in the locked state. */
+ * Returns the object in the locked state and with a reference taken. */
 BlueSkyCacheFile *bluesky_cachefile_lookup(BlueSkyFS *fs,
-                                         int clouddir, int log_seq)
+                                           int clouddir, int log_seq)
 {
     if (page_size == 0) {
         page_size = getpagesize();
@@ -308,35 +330,41 @@ BlueSkyCacheFile *bluesky_cachefile_lookup(BlueSkyFS *fs,
 
     BlueSkyLog *log = fs->log;
 
+    char logname[64];
+    int type;
+
+    // A request for a local log file
+    if (clouddir < 0) {
+        sprintf(logname, "journal-%08d", log_seq);
+        type = CLOUDLOG_JOURNAL;
+    } else {
+        sprintf(logname, "log-%08d-%08d", clouddir, log_seq);
+        type = CLOUDLOG_CLOUD;
+    }
+
     BlueSkyCacheFile *map;
     g_mutex_lock(log->mmap_lock);
-    map = g_hash_table_lookup(log->mmap_cache, GINT_TO_POINTER(log_seq));
+    map = g_hash_table_lookup(log->mmap_cache, logname);
 
     if (map == NULL) {
-        char *logname;
-
-        // A request for a local log file
-        if (clouddir < 0) {
-            logname = g_strdup_printf("journal-%08d", log_seq);
-        } else {
-            logname = g_strdup_printf("log-%08d-%08d", clouddir, log_seq);
-        }
-
         /* TODO: stat() call */
         map = g_new0(BlueSkyCacheFile, 1);
         map->type = CLOUDLOG_JOURNAL;
         map->lock = g_mutex_new();
+        map->type = type;
         g_mutex_lock(map->lock);
         map->cond = g_cond_new();
-        map->filename = logname;
+        map->filename = g_strdup(logname);
         map->log_seq = log_seq;
         map->log = log;
+        g_atomic_int_set(&map->mapcount, 0);
         g_atomic_int_set(&map->refcount, 0);
 
-        g_hash_table_insert(log->mmap_cache, GINT_TO_POINTER(log_seq), map);
+        g_hash_table_insert(log->mmap_cache, map->filename, map);
 
         // If the log file is stored in the cloud, we may need to fetch it
         if (clouddir >= 0) {
+            g_atomic_int_inc(&map->refcount);
             map->fetching = TRUE;
             g_print("Starting fetch of %s from cloud\n", logname);
             BlueSkyStoreAsync *async = bluesky_store_async_new(fs->store);
@@ -353,6 +381,7 @@ BlueSkyCacheFile *bluesky_cachefile_lookup(BlueSkyFS *fs,
     }
 
     g_mutex_unlock(log->mmap_lock);
+    g_atomic_int_inc(&map->refcount);
     return map;
 }
 
@@ -380,6 +409,7 @@ BlueSkyRCStr *bluesky_log_map_object(BlueSkyFS *fs, int log_dir,
 
         if (fd < 0) {
             fprintf(stderr, "Error opening logfile %s: %m\n", map->filename);
+            bluesky_cachefile_unref(map);
             g_mutex_unlock(map->lock);
             return NULL;
         }
@@ -387,9 +417,12 @@ BlueSkyRCStr *bluesky_log_map_object(BlueSkyFS *fs, int log_dir,
         off_t length = lseek(fd, 0, SEEK_END);
         map->addr = (const char *)mmap(NULL, length, PROT_READ, MAP_SHARED,
                                        fd, 0);
+        g_atomic_int_add(&log->disk_used, -(map->len / 1024));
         map->len = length;
+        g_atomic_int_add(&log->disk_used, map->len / 1024);
 
         g_print("Re-mapped log segment %d...\n", log_seq);
+        g_atomic_int_inc(&map->refcount);
 
         close(fd);
     }
@@ -397,7 +430,9 @@ BlueSkyRCStr *bluesky_log_map_object(BlueSkyFS *fs, int log_dir,
     g_mutex_unlock(log->mmap_lock);
 
     BlueSkyRCStr *str;
+    map->atime = bluesky_get_current_time();
     str = bluesky_string_new_from_mmap(map, log_offset, log_size);
+    bluesky_cachefile_unref(map);
     g_mutex_unlock(map->lock);
     return str;
 }
@@ -407,15 +442,91 @@ void bluesky_mmap_unref(BlueSkyCacheFile *mmap)
     if (mmap == NULL)
         return;
 
-    if (g_atomic_int_dec_and_test(&mmap->refcount)) {
+    if (g_atomic_int_dec_and_test(&mmap->mapcount)) {
         g_mutex_lock(mmap->lock);
-        if (g_atomic_int_get(&mmap->refcount) > 0) {
+        if (g_atomic_int_get(&mmap->mapcount) == 0) {
             g_print("Unmapped log segment %d...\n", mmap->log_seq);
             munmap((void *)mmap->addr, mmap->len);
             mmap->addr = NULL;
-            return;
+            g_atomic_int_add(&mmap->refcount, -1);
         }
         g_mutex_unlock(mmap->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 dirty=%d atime_age=%f",
+                    cachefile->filename, cachefile->addr, cachefile->mapcount,
+                    cachefile->refcount, cachefile->dirty_refs, age / 1e6);
+            if (cachefile->fetching)
+                g_print(" (fetching)");
+            g_print("\n");
+
+            if (g_atomic_int_get(&cachefile->refcount) == 0
+                && g_atomic_int_get(&cachefile->mapcount) == 0
+                && g_atomic_int_get(&cachefile->dirty_refs) == 0)
+            {
+                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_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);
+}