Add in some support for journal replay.

[bluesky.git] / bluesky / log.c

diff --git a/bluesky/log.c b/bluesky/log.c
index 1459ee4..e79b21b 100644 (file)
--- a/bluesky/log.c
+++ b/bluesky/log.c
@@ -569,6 +569,26 @@ void bluesky_cachefile_gc(BlueSkyFS *fs)
  * also been committed to the cloud.  Then, we read in all data in the log past
  * that point.
  */
+static GList *directory_contents(const char *dirname)
+{
+    GList *contents = NULL;
+    GDir *dir = g_dir_open(dirname, 0, NULL);
+    if (dir == NULL) {
+        g_warning("Unable to open journal directory: %s", dirname);
+        return NULL;
+    }
+
+    const gchar *file;
+    while ((file = g_dir_read_name(dir)) != NULL) {
+        if (strncmp(file, "journal-", 8) == 0)
+            contents = g_list_prepend(contents, g_strdup(file));
+    }
+    g_dir_close(dir);
+
+    contents = g_list_sort(contents, (GCompareFunc)strcmp);
+
+    return contents;
+}
 
 static gboolean validate_journal_item(const char *buf, size_t len, off_t offset)
 {
@@ -611,10 +631,45 @@ static void bluesky_replay_scan_journal(const char *buf, size_t len)
 
     while (validate_journal_item(buf, len, offset)) {
         header = (const struct log_header *)(buf + offset);
-        g_print("In replay found valid item at offset %zd\n", offset);
+        size_t size = GUINT32_FROM_LE(header->size);
+        offset += sizeof(struct log_header) + size + sizeof(struct log_footer);
+    }
+}
 
+static void bluesky_replay_scan_journal2(BlueSkyFS *fs, GList **objects,
+                                         int log_seq,
+                                         const char *buf, size_t len)
+{
+    const struct log_header *header;
+    off_t offset = 0;
+
+    while (validate_journal_item(buf, len, offset)) {
+        header = (const struct log_header *)(buf + offset);
+        g_print("In replay found valid item at offset %zd\n", offset);
         size_t size = GUINT32_FROM_LE(header->size);
 
+        g_mutex_lock(fs->lock);
+        BlueSkyCloudLog *log_item;
+        log_item = g_hash_table_lookup(fs->locations, &header->id);
+        if (log_item == NULL) {
+            log_item = bluesky_cloudlog_new(fs, &header->id);
+            g_hash_table_insert(fs->locations, &log_item->id, log_item);
+            g_mutex_lock(log_item->lock);
+        } else {
+            bluesky_cloudlog_ref(log_item);
+            g_mutex_lock(log_item->lock);
+        }
+        g_mutex_unlock(fs->lock);
+        *objects = g_list_prepend(*objects, log_item);
+
+        bluesky_string_unref(log_item->data);
+        log_item->location_flags = CLOUDLOG_JOURNAL;
+        log_item->data = NULL;
+        log_item->log_seq = log_seq;
+        log_item->log_offset = offset + sizeof(struct log_header);
+        log_item->log_size = header->size;
+        g_mutex_unlock(log_item->lock);
+
         offset += sizeof(struct log_header) + size + sizeof(struct log_footer);
     }
 }
@@ -622,21 +677,58 @@ static void bluesky_replay_scan_journal(const char *buf, size_t len)
 void bluesky_replay(BlueSkyFS *fs)
 {
     BlueSkyLog *log = fs->log;
-    char logname[64];
-    int seq_num = 0;
-    int fd;
-
-    g_snprintf(logname, sizeof(logname), "journal-%08d", seq_num);
-    fd = openat(log->dirfd, logname, O_RDONLY);
-    if (fd < 0)
-        return;
+    GList *logfiles = directory_contents(log->log_directory);
+
+    /* Scan through log files in reverse order to find the most recent commit
+     * record. */
+    logfiles = g_list_reverse(logfiles);
+    while (logfiles != NULL) {
+        char *filename = g_strdup_printf("%s/%s", log->log_directory,
+                                         (char *)logfiles->data);
+        g_print("Scanning file %s\n", filename);
+        GMappedFile *map = g_mapped_file_new(filename, FALSE, NULL);
+        if (map == NULL) {
+            g_warning("Mapping logfile %s failed!\n", filename);
+        } else {
+            bluesky_replay_scan_journal(g_mapped_file_get_contents(map),
+                                        g_mapped_file_get_length(map));
+            g_mapped_file_unref(map);
+        }
+        g_free(filename);
 
-    off_t length = lseek(fd, 0, SEEK_END);
-    void *addr = mmap(NULL, length, PROT_READ, MAP_SHARED, fd, 0);
-    if (addr == NULL)
-        return;
+        g_free(logfiles->data);
+        logfiles = g_list_delete_link(logfiles, logfiles);
+    }
+    g_list_foreach(logfiles, (GFunc)g_free, NULL);
+    g_list_free(logfiles);
+
+    /* Now, scan forward starting from the given point in the log to
+     * reconstruct all filesystem state.  As we reload objects we hold a
+     * reference to each loaded object.  At the end we free all these
+     * references, so that any objects which were not linked into persistent
+     * filesystem data structures are freed. */
+    GList *objects = NULL;
+    int seq_num = 0;
+    while (TRUE) {
+        char *filename = g_strdup_printf("%s/journal-%08d",
+                                         log->log_directory, seq_num);
+        g_print("Replaying file %s\n", filename);
+        GMappedFile *map = g_mapped_file_new(filename, FALSE, NULL);
+        g_free(filename);
+        if (map == NULL) {
+            g_warning("Mapping logfile failed, assuming end of journal\n");
+            break;
+        }
 
-    bluesky_replay_scan_journal((const char *)addr, length);
+        bluesky_replay_scan_journal2(fs, &objects, seq_num,
+                                     g_mapped_file_get_contents(map),
+                                     g_mapped_file_get_length(map));
+        g_mapped_file_unref(map);
+        seq_num++;
+    }
 
-    munmap(addr, length);
+    while (objects != NULL) {
+        bluesky_cloudlog_unref((BlueSkyCloudLog *)objects->data);
+        objects = g_list_delete_link(objects, objects);
+    }
 }