X-Git-Url: http://git.vrable.net/?a=blobdiff_plain;f=bluesky%2Flog.c;h=1fe61769b92870b95022fcc8933b70d3a9e689d3;hb=7795e004d36e779abdf77f8771488595839e4bee;hp=9ba75b471b1b4f4225c1c02fe3dc1d46c559acb2;hpb=97517d1bbc647846003d1a49b6ae97c69d856b90;p=bluesky.git

diff --git a/bluesky/log.c b/bluesky/log.c
index 9ba75b4..1fe6176 100644
--- a/bluesky/log.c
+++ b/bluesky/log.c
@@ -36,7 +36,7 @@
 
 // Rough size limit for a log segment.  This is not a firm limit and there are
 // no absolute guarantees on the size of a log segment.
-#define LOG_SEGMENT_SIZE (1 << 24)
+#define LOG_SEGMENT_SIZE (1 << 22)
 
 #define HEADER_MAGIC 0x676f4c0a
 #define FOOTER_MAGIC 0x2e435243
@@ -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);
     }
@@ -234,7 +243,7 @@ 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) {
@@ -278,26 +287,47 @@ void bluesky_cachefile_unref(BlueSkyCacheFile *cachefile)
     g_atomic_int_add(&cachefile->refcount, -1);
 }
 
+static void cloudlog_fetch_complete(BlueSkyStoreAsync *async,
+                                    BlueSkyCacheFile *cachefile);
+
+static void cloudlog_fetch_start(BlueSkyCacheFile *cachefile)
+{
+    g_atomic_int_inc(&cachefile->refcount);
+    cachefile->fetching = TRUE;
+    g_print("Starting fetch of %s from cloud\n", cachefile->filename);
+    BlueSkyStoreAsync *async = bluesky_store_async_new(cachefile->fs->store);
+    async->op = STORE_OP_GET;
+    async->key = g_strdup(cachefile->filename);
+    bluesky_store_async_add_notifier(async,
+                                     (GFunc)cloudlog_fetch_complete,
+                                     cachefile);
+    bluesky_store_async_submit(async);
+    bluesky_store_async_unref(async);
+}
+
 static void cloudlog_fetch_complete(BlueSkyStoreAsync *async,
                                     BlueSkyCacheFile *cachefile)
 {
     g_print("Fetch of %s from cloud complete, status = %d\n",
             async->key, async->result);
 
-    if (async->result < 0)
-        return;
-
     g_mutex_lock(cachefile->lock);
-    char *pathname = g_strdup_printf("%s/%s", cachefile->log->log_directory,
-                                     cachefile->filename);
-    if (!g_file_set_contents(pathname, async->data->data, async->data->len,
-                             NULL))
-    {
-        g_print("Error writing out fetched file to cache!\n");
+    if (async->result >= 0) {
+        char *pathname = g_strdup_printf("%s/%s",
+                                         cachefile->log->log_directory,
+                                         cachefile->filename);
+        if (!g_file_set_contents(pathname, async->data->data, async->data->len,
+                                 NULL))
+            g_print("Error writing out fetched file to cache!\n");
+        g_free(pathname);
+
+        cachefile->fetching = FALSE;
+        cachefile->ready = TRUE;
+    } else {
+        g_print("Error fetching from cloud, retrying...\n");
+        cloudlog_fetch_start(cachefile);
     }
-    g_free(pathname);
-    cachefile->fetching = FALSE;
-    cachefile->ready = TRUE;
+
     bluesky_cachefile_unref(cachefile);
     g_cond_broadcast(cachefile->cond);
     g_mutex_unlock(cachefile->lock);
@@ -306,7 +336,7 @@ static void cloudlog_fetch_complete(BlueSkyStoreAsync *async,
 /* Find the BlueSkyCacheFile object for the given journal or cloud log segment.
  * 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();
@@ -314,54 +344,56 @@ BlueSkyCacheFile *bluesky_cachefile_lookup(BlueSkyFS *fs,
 
     BlueSkyLog *log = fs->log;
 
+    struct stat statbuf;
+    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);
-        }
+    if (map == NULL
+        && type == CLOUDLOG_JOURNAL
+        && fstatat(log->dirfd, logname, &statbuf, 0) < 0) {
+        /* A stale reference to a journal file which doesn't exist any longer
+         * because it was reclaimed.  Return NULL. */
+    } else if (map == NULL) {
+        g_print("Adding cache file %s\n", logname);
 
-        /* TODO: stat() call */
         map = g_new0(BlueSkyCacheFile, 1);
-        map->type = CLOUDLOG_JOURNAL;
+        map->fs = fs;
+        map->type = type;
         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);
-            async->op = STORE_OP_GET;
-            async->key = g_strdup(logname);
-            bluesky_store_async_add_notifier(async,
-                                             (GFunc)cloudlog_fetch_complete,
-                                             map);
-            bluesky_store_async_submit(async);
-            bluesky_store_async_unref(async);
-        }
+        if (clouddir >= 0)
+            cloudlog_fetch_start(map);
     } else {
         g_mutex_lock(map->lock);
     }
 
     g_mutex_unlock(log->mmap_lock);
-    g_atomic_int_inc(&map->refcount);
+    if (map != NULL)
+        g_atomic_int_inc(&map->refcount);
     return map;
 }
 
@@ -397,7 +429,9 @@ 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);
@@ -431,3 +465,95 @@ void bluesky_mmap_unref(BlueSkyCacheFile *mmap)
         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 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);
+}