X-Git-Url: http://git.vrable.net/?a=blobdiff_plain;f=bluesky%2Fcloudlog.c;h=40067fd3661f91d4ec9e45a9019a73d9043c8bd6;hb=a82b60b3b683840a7074110831bcbaa16a40f0eb;hp=d7cea634f50f6762675b94b647ac60f75bd59f1d;hpb=a8a9f2181e2e16d24d812ea1e7a7c8af42f0d2f1;p=bluesky.git

diff --git a/bluesky/cloudlog.c b/bluesky/cloudlog.c
index d7cea63..40067fd 100644
--- a/bluesky/cloudlog.c
+++ b/bluesky/cloudlog.c
@@ -13,13 +13,9 @@
 
 #include "bluesky-private.h"
 
-/* The locations hash table in the file system is used to map objects to their locations.  Objects are named using 128- */
-
-typedef struct {
-    BlueSkyCloudID id;
-
-    BlueSkyCloudPointer *cloud_loc;
-} BlueSkyLocationEntry;
+// 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 CLOUDLOG_SEGMENT_SIZE (4 << 20)
 
 BlueSkyCloudID bluesky_cloudlog_new_id()
 {
@@ -91,12 +87,41 @@ BlueSkyCloudLog *bluesky_cloudlog_new(BlueSkyFS *fs)
     log->fs = fs;
     log->type = LOGTYPE_UNKNOWN;
     log->id = bluesky_cloudlog_new_id();
-    log->pointers = g_array_new(FALSE, TRUE, sizeof(BlueSkyCloudID));
+    log->links = g_array_new(FALSE, TRUE, sizeof(BlueSkyCloudLog *));
     g_atomic_int_set(&log->refcount, 1);
 
     return log;
 }
 
+/* Helper function for updating memory usage statistics for a filesystem (the
+ * cache_log_* variables).  This will increment (type=1) or decrement (type=-1)
+ * the counter associated with the current state of the cloud log item.  The
+ * item should be locked or otherwise protected from concurrent access. */
+void bluesky_cloudlog_stats_update(BlueSkyCloudLog *log, int type)
+{
+    BlueSkyFS *fs = log->fs;
+
+    if (log->location_flags & CLOUDLOG_CLOUD) {
+        g_atomic_int_add(&fs->cache_log_cloud, type);
+    } else if (log->location_flags & CLOUDLOG_JOURNAL) {
+        g_atomic_int_add(&fs->cache_log_journal, type);
+    } else if (log->pending_write & CLOUDLOG_JOURNAL) {
+        g_atomic_int_add(&fs->cache_log_journal, type);
+    } else if (log->data != NULL) {
+        g_atomic_int_add(&fs->cache_log_dirty, type);
+    }
+}
+
+/* The reference held by the hash table does not count towards the reference
+ * count.  When a new object is created, it initially has a reference count of
+ * 1 for the creator, and similarly fetching an item from the hash table will
+ * also create a reference.  If the reference count drops to zero,
+ * bluesky_cloudlog_unref attempts to remove the object from the hash
+ * table--but there is a potential race since another thread might read the
+ * object from the hash table at the same time.  So an object with a reference
+ * count of zero may still be resurrected, in which case we need to abort the
+ * destruction.  Once the object is gone from the hash table, and if the
+ * reference count is still zero, it can actually be deleted. */
 void bluesky_cloudlog_ref(BlueSkyCloudLog *log)
 {
     if (log == NULL)
@@ -111,7 +136,29 @@ void bluesky_cloudlog_unref(BlueSkyCloudLog *log)
         return;
 
     if (g_atomic_int_dec_and_test(&log->refcount)) {
-        g_print("Cloud log refcount dropped to zero.\n");
+        BlueSkyFS *fs = log->fs;
+
+        g_mutex_lock(fs->lock);
+        if (g_atomic_int_get(&log->refcount) > 0) {
+            g_mutex_unlock(fs->lock);
+            return;
+        }
+
+        g_hash_table_remove(fs->locations, &log->id);
+        g_mutex_unlock(fs->lock);
+
+        bluesky_cloudlog_stats_update(log, -1);
+        log->type = LOGTYPE_INVALID;
+        g_mutex_free(log->lock);
+        g_cond_free(log->cond);
+        for (int i = 0; i < log->links->len; i++) {
+            BlueSkyCloudLog *c = g_array_index(log->links,
+                                               BlueSkyCloudLog *, i);
+            bluesky_cloudlog_unref(c);
+        }
+        g_array_unref(log->links);
+        bluesky_string_unref(log->data);
+        g_free(log);
     }
 }
 
@@ -147,36 +194,67 @@ struct log_footer {
     struct logref refs[0];
 };
 
+/* Ensure that a cloud log item is loaded in memory, and if not read it in.
+ * TODO: Make asynchronous, and make this also fetch from the cloud.  Right now
+ * we only read from the log.  Log item must be locked. */
+void bluesky_cloudlog_fetch(BlueSkyCloudLog *log)
+{
+    if (log->data != NULL)
+        return;
+
+    if ((log->location_flags | log->pending_write) & CLOUDLOG_JOURNAL) {
+        bluesky_cloudlog_stats_update(log, -1);
+        log->data = bluesky_log_map_object(log->fs, -1, log->log_seq,
+                                           log->log_offset, log->log_size);
+        bluesky_cloudlog_stats_update(log, 1);
+    }
+
+    if (log->data == NULL && (log->location_flags & CLOUDLOG_CLOUD)) {
+        log->location_flags &= ~CLOUDLOG_JOURNAL;
+        bluesky_cloudlog_stats_update(log, -1);
+        log->data = bluesky_log_map_object(log->fs, log->location.directory,
+                                           log->location.sequence,
+                                           log->location.offset,
+                                           log->location.size);
+        bluesky_cloudlog_stats_update(log, 1);
+    }
+
+    if (log->data == NULL) {
+        g_error("Unable to fetch cloudlog entry!");
+    }
+
+    g_cond_broadcast(log->cond);
+}
+
 BlueSkyCloudPointer bluesky_cloudlog_serialize(BlueSkyCloudLog *log,
-                                               BlueSkyCloudLogState *state)
+                                               BlueSkyFS *fs)
 {
-    if (log->location_flags & CLOUDLOG_CLOUD) {
+    BlueSkyCloudLogState *state = fs->log_state;
+
+    if ((log->location_flags | log->pending_write) & CLOUDLOG_CLOUD) {
         return log->location;
     }
 
-    g_print("Flushing object %s to cloud...\n",
-            bluesky_cloudlog_id_to_string(log->id));
-
-    for (int i = 0; i < log->pointers->len; i++) {
-        BlueSkyCloudID id = g_array_index(log->pointers, BlueSkyCloudID, i);
-        g_print("  ...checking reference %s...\n",
-                bluesky_cloudlog_id_to_string(id));
-        g_mutex_lock(log->fs->lock);
-        BlueSkyCloudLog *log2
-            = (BlueSkyCloudLog *)g_hash_table_lookup(log->fs->locations, &id);
-        // TODO: refcount
-        g_mutex_unlock(log->fs->lock);
-        g_assert(log2 != NULL);
-        bluesky_cloudlog_serialize(log2, state);
+    for (int i = 0; i < log->links->len; i++) {
+        BlueSkyCloudLog *ref = g_array_index(log->links,
+                                             BlueSkyCloudLog *, i);
+        if (ref != NULL)
+            bluesky_cloudlog_serialize(ref, fs);
     }
 
+    g_mutex_lock(log->lock);
+    bluesky_cloudlog_fetch(log);
     g_assert(log->data != NULL);
 
+    bluesky_cloudlog_stats_update(log, -1);
+
+    /* TODO: Right now offset/size are set to the raw data, but we should add
+     * header parsing to the code which loads objects back in. */
     log->location = state->location;
-    log->location.offset = state->data->len;
-    log->location.size
-        = sizeof(struct log_header) + sizeof(BlueSkyCloudID) * 0
-           + log->data->len;
+    log->location.offset = state->data->len + sizeof(struct log_header);
+    log->location.size = log->data->len;
+        /* = sizeof(struct log_header) + sizeof(BlueSkyCloudID) * 0
+           + log->data->len; */
 
     struct log_header header;
     memcpy(header.magic, "AgI ", 4);
@@ -187,75 +265,107 @@ BlueSkyCloudPointer bluesky_cloudlog_serialize(BlueSkyCloudLog *log,
     g_string_append_len(state->data, (const char *)&header, sizeof(header));
     g_string_append_len(state->data, log->data->data, log->data->len);
 
-    log->location_flags |= CLOUDLOG_CLOUD;
-
-    return log->location;
-}
+    /* If the object we flushed was an inode, update the inode map. */
+    if (log->type == LOGTYPE_INODE) {
+        g_mutex_lock(fs->lock);
+        InodeMapEntry *entry = bluesky_inode_map_lookup(fs->inode_map,
+                                                        log->inum, 1);
+        entry->id = log->id;
+        entry->location = log->location;
+        g_mutex_unlock(fs->lock);
+    }
 
-static void find_inodes(gpointer key, gpointer value, gpointer user_data)
-{
-    BlueSkyCloudLogState *state = (BlueSkyCloudLogState *)user_data;
-    BlueSkyCloudLog *item = (BlueSkyCloudLog *)value;
+    /* TODO: We should mark the objects as committed on the cloud until the
+     * data is flushed and acknowledged. */
+    log->pending_write |= CLOUDLOG_CLOUD;
+    bluesky_cloudlog_stats_update(log, 1);
+    state->writeback_list = g_slist_prepend(state->writeback_list, log);
+    bluesky_cloudlog_ref(log);
+    g_mutex_unlock(log->lock);
 
-    if (item->type != LOGTYPE_INODE)
-        return;
+    if (state->data->len > CLOUDLOG_SEGMENT_SIZE)
+        bluesky_cloudlog_flush(fs);
 
-    bluesky_cloudlog_ref(item);
-    state->inode_list = g_list_prepend(state->inode_list, item);
+    return log->location;
 }
 
-void bluesky_cloudlog_write_log(BlueSkyFS *fs)
+static void cloudlog_flush_complete(BlueSkyStoreAsync *async,
+                                    SerializedRecord *record)
 {
-    g_print("Starting cloudlog write...\n");
-
-    BlueSkyCloudLogState *state = fs->log_state;
-    if (state->data == NULL)
-        state->data = g_string_new("");
-
-    g_mutex_lock(fs->lock);
-    g_hash_table_foreach(fs->locations, find_inodes, state);
-    g_mutex_unlock(fs->lock);
-
-    while (state->inode_list != NULL) {
-        BlueSkyCloudLog *log = (BlueSkyCloudLog *)state->inode_list->data;
-        bluesky_cloudlog_serialize(log, state);
-        state->inode_list = g_list_delete_link(state->inode_list,
-                                               state->inode_list);
-    }
+    g_print("Write of %s to cloud complete, status = %d\n",
+            async->key, async->result);
+
+    g_mutex_lock(record->lock);
+    if (async->result >= 0) {
+        while (record->items != NULL) {
+            BlueSkyCloudLog *item = (BlueSkyCloudLog *)record->items->data;
+            g_mutex_lock(item->lock);
+            bluesky_cloudlog_stats_update(item, -1);
+            item->pending_write &= ~CLOUDLOG_CLOUD;
+            item->location_flags |= CLOUDLOG_CLOUD;
+            bluesky_cloudlog_stats_update(item, 1);
+            g_mutex_unlock(item->lock);
+            bluesky_cloudlog_unref(item);
+
+            record->items = g_slist_delete_link(record->items, record->items);
+        }
 
-    if (state->data->len > 0) {
-        g_print("Serialized %zd bytes of data\n", state->data->len);
-
-        BlueSkyStoreAsync *async = bluesky_store_async_new(fs->store);
-        async->op = STORE_OP_PUT;
-        async->key = g_strdup_printf("log-%08d-%08d",
-                                     state->location.directory,
-                                     state->location.sequence);
-        async->data = bluesky_string_new_from_gstring(state->data);
-        bluesky_store_async_submit(async);
-        bluesky_store_async_wait(async);
-        bluesky_store_async_unref(async);
-
-        state->location.sequence++;
-        state->location.offset = 0;
+        bluesky_string_unref(record->data);
+        record->data = NULL;
+        g_slist_free(record->items);
+        record->items = NULL;
+        record->complete = TRUE;
+        g_cond_broadcast(record->cond);
+    } else {
+        g_print("Write should be resubmitted...\n");
+
+        BlueSkyStoreAsync *async2 = bluesky_store_async_new(async->store);
+        async2->op = STORE_OP_PUT;
+        async2->key = g_strdup(async->key);
+        async2->data = record->data;
+        bluesky_string_ref(record->data);
+        bluesky_store_async_submit(async2);
+        bluesky_store_async_add_notifier(async2,
+                                         (GFunc)cloudlog_flush_complete,
+                                         record);
+        bluesky_store_async_unref(async2);
     }
-
-    state->data = NULL;
+    g_mutex_unlock(record->lock);
 }
 
-/* Ensure that a cloud log item is loaded in memory, and if not read it in.
- * TODO: Make asynchronous, and make this also fetch from the cloud.  Right now
- * we only read from the log.  Log item must be locked. */
-void bluesky_cloudlog_fetch(BlueSkyCloudLog *log)
+/* Finish up a partially-written cloud log segment and flush it to storage. */
+void bluesky_cloudlog_flush(BlueSkyFS *fs)
 {
-    if (log->data != NULL)
+    BlueSkyCloudLogState *state = fs->log_state;
+    if (state->data == NULL || state->data->len == 0)
         return;
 
-    g_print("Re-mapping log entry %d/%d/%d...\n",
-            log->log_seq, log->log_offset, log->log_size);
-
-    g_assert(log->location_flags & CLOUDLOG_JOURNAL);
-
-    log->data = bluesky_log_map_object(log->fs->log, log->log_seq,
-                                       log->log_offset, log->log_size);
+    /* TODO: Append some type of commit record to the log segment? */
+
+    g_print("Serializing %zd bytes of data to cloud\n", state->data->len);
+    SerializedRecord *record = g_new0(SerializedRecord, 1);
+    record->data = bluesky_string_new_from_gstring(state->data);
+    record->items = state->writeback_list;
+    record->lock = g_mutex_new();
+    record->cond = g_cond_new();
+    state->writeback_list = NULL;
+
+    BlueSkyStoreAsync *async = bluesky_store_async_new(fs->store);
+    async->op = STORE_OP_PUT;
+    async->key = g_strdup_printf("log-%08d-%08d",
+                                 state->location.directory,
+                                 state->location.sequence);
+    async->data = record->data;
+    bluesky_string_ref(record->data);
+    bluesky_store_async_submit(async);
+    bluesky_store_async_add_notifier(async,
+                                     (GFunc)cloudlog_flush_complete,
+                                     record);
+    bluesky_store_async_unref(async);
+
+    state->pending_segments = g_list_prepend(state->pending_segments, record);
+
+    state->location.sequence++;
+    state->location.offset = 0;
+    state->data = g_string_new("");
 }