* rewriting log segments where needed and deleting old segments, is handled by
* the in-cloud cleaner component. */
+/* A specialized function for loading an object from the cloud, used just by
+ * the cleaner. When the cleaner runs, it will produce new objects that have
+ * the same object ID as before, differing only in the outgoing link locations
+ * as a result of cleaning. We can't use the normal functions for loading
+ * objects since those can only deal with one version of an object. Instead,
+ * we load the cleaned object with this function, and then merge the state into
+ * the official object as needed.
+ *
+ * The bluesky_cleaner_deserialize function is like
+ * bluesky_deserialize_cloudlog, but does a more limited deserialization and
+ * keeps the returned item entirely separate from any in-memory BlueSkyCloudLog
+ * objects. */
+
+typedef struct {
+ BlueSkyCloudLogType type;
+ BlueSkyCloudID id;
+ BlueSkyCloudPointer location;
+ uint64_t inum;
+ GArray *links;
+} BlueSkyCleanerItem;
+
+typedef struct {
+ BlueSkyCloudID id;
+ BlueSkyCloudPointer location;
+} BlueSkyCleanerLink;
+
+static BlueSkyCleanerItem *bluesky_cleaner_deserialize(BlueSkyRCStr *raw)
+{
+ const char *data = raw->data;
+ size_t len = raw->len;
+ const char *data1, *data2, *data3;
+ size_t len1, len2, len3;
+
+ g_assert(len > 4);
+ if (len < sizeof(struct cloudlog_header)
+ || memcmp(data, CLOUDLOG_MAGIC, 4) != 0)
+ {
+ g_warning("Deserializing garbage cloud log item from cleaner!");
+ return NULL;
+ };
+
+ struct cloudlog_header *header = (struct cloudlog_header *)data;
+ len1 = GUINT32_FROM_LE(header->size1);
+ len2 = GUINT32_FROM_LE(header->size2);
+ len3 = GUINT32_FROM_LE(header->size3);
+ data1 = data + sizeof(struct cloudlog_header);
+ data2 = data1 + len1;
+ data3 = data2 + len2;
+ g_assert(data3 + len3 - data <= len);
+
+ BlueSkyCleanerItem *item = g_new0(BlueSkyCleanerItem, 1);
+ item->type = header->type - '0';
+ item->inum = GUINT64_FROM_LE(header->inum);
+ memcpy(&item->id, &header->id, sizeof(BlueSkyCloudID));
+
+ int link_count = len2 / sizeof(BlueSkyCloudID);
+ g_print("Outgoing links: %d\n", link_count);
+ item->links = g_array_new(FALSE, TRUE, sizeof(BlueSkyCleanerLink));
+ for (int i = 0; i < link_count; i++) {
+ BlueSkyCleanerLink link;
+
+ g_assert(len2 >= sizeof(link.id));
+ memcpy(&link.id, data2, sizeof(link.id));
+ data2 += sizeof(link.id); len2 -= sizeof(link.id);
+
+ g_assert(len3 >= sizeof(link.location));
+ memcpy(&link.location, data3, sizeof(link.location));
+ data3 += sizeof(link.location); len3 -= sizeof(link.location);
+
+ g_array_append_val(item->links, link);
+ }
+
+ return item;
+}
+
+static void bluesky_cleaner_item_free(BlueSkyCleanerItem *item)
+{
+ if (item == NULL)
+ return;
+ g_array_unref(item->links);
+ g_free(item);
+}
+
/* Check the cleaner's logs to find the a more recent checkpoint record. This
* should be called occasionally to see if the cleaner has done any work since
* our last check. */
-void bluesky_cleaner_find_checkpoint(BlueSkyFS *fs)
+static BlueSkyCleanerItem *bluesky_cleaner_find_checkpoint(BlueSkyFS *fs)
{
char *prefix = g_strdup_printf("log-%08d", BLUESKY_CLOUD_DIR_CLEANER);
char *last_segment = bluesky_store_lookup_last(fs->store, prefix);
g_free(prefix);
if (last_segment == NULL)
- return;
+ return NULL;
g_print("Last cloud log segment: %s\n", last_segment);
int seq = atoi(last_segment + 13);
g_free(last_segment);
if (seq <= fs->log_state->latest_cleaner_seq_seen)
- return;
+ return NULL;
g_print("New log segment appeared in cleaner directory: %d\n", seq);
length = item->length;
}
- if (length > 0) {
- g_print("Last object: %"PRIu64" + %"PRIu64"\n", offset, length);
- }
+ if (length == 0)
+ return NULL;
+
+ g_print("Found a cleaner checkpoint record.\n");
+
+ BlueSkyRCStr *data = bluesky_cachefile_map_raw(cachefile, offset, length);
+ bluesky_cachefile_unref(cachefile);
+ g_mutex_unlock(cachefile->lock);
+ BlueSkyCleanerItem *checkpoint = bluesky_cleaner_deserialize(data);
+ bluesky_string_unref(data);
+
+ return checkpoint;
+}
+
+static BlueSkyCleanerItem *cleaner_load_item(BlueSkyFS *fs,
+ BlueSkyCloudPointer location)
+{
+ g_print("Loading item %d/%d/%d...\n", location.directory, location.sequence, location.offset);
+
+ BlueSkyCacheFile *cachefile;
+ cachefile = bluesky_cachefile_lookup(fs, location.directory,
+ location.sequence, TRUE);
+ while (!cachefile->complete)
+ g_cond_wait(cachefile->cond, cachefile->lock);
+
+ /* TODO: Ought to check that we are loading an item which validated? */
+ BlueSkyRCStr *data = bluesky_cachefile_map_raw(cachefile, location.offset,
+ location.size);
bluesky_cachefile_unref(cachefile);
g_mutex_unlock(cachefile->lock);
+
+ BlueSkyCleanerItem *item = bluesky_cleaner_deserialize(data);
+ bluesky_string_unref(data);
+
+ return item;
+}
+
+/* Does the item at the given cloud location from the cleaner need merging? An
+ * item in the primary log does not need to be merged, as by definition we
+ * already know about it. Similarly, old items in the cleaner's log--those
+ * that we have already seen from a previous merge--do not need to be mergd
+ * again. */
+gboolean needs_merging(BlueSkyFS *fs, BlueSkyCloudPointer location)
+{
+ if (location.directory == BLUESKY_CLOUD_DIR_PRIMARY)
+ return FALSE;
+
+ return TRUE;
+}
+
+void bluesky_cleaner_merge(BlueSkyFS *fs)
+{
+ BlueSkyCleanerItem *checkpoint = bluesky_cleaner_find_checkpoint(fs);
+
+ if (checkpoint == NULL) {
+ g_warning("Unable to load cleaner checkpoint record!");
+ return;
+ }
+
+ /* Iterate over each of the inode map sections in the checkpoint */
+ for (int i = 0; i < checkpoint->links->len; i++) {
+ BlueSkyCleanerLink *link = &g_array_index(checkpoint->links,
+ BlueSkyCleanerLink, i);
+ /*if (!needs_merging(fs, link->location))
+ continue; */
+
+ BlueSkyCleanerItem *imap = cleaner_load_item(fs, link->location);
+ if (imap == NULL) {
+ g_warning("Unable to load cleaner inode map");
+ continue;
+ }
+
+ /* Iterate over all inodes found in the inode map section */
+ for (int j = 0; j < imap->links->len; j++) {
+ BlueSkyCleanerLink *link = &g_array_index(imap->links,
+ BlueSkyCleanerLink, j);
+ BlueSkyCleanerItem *inode = cleaner_load_item(fs, link->location);
+ if (inode != NULL) {
+ g_print("Got inode %"PRIu64"\n", inode->inum);
+ }
+ bluesky_cleaner_item_free(inode);
+ }
+
+ bluesky_cleaner_item_free(imap);
+ }
+
+ bluesky_cleaner_item_free(checkpoint);
}
#define HEADER_MAGIC 0x676f4c0a
#define FOOTER_MAGIC 0x2e435243
+static size_t readbuf(int fd, char *buf, size_t len)
+{
+ size_t total_bytes = 0;
+ while (len > 0) {
+ ssize_t bytes = read(fd, buf, len);
+ if (bytes < 0 && errno == EINTR)
+ continue;
+ g_assert(bytes >= 0);
+ if (bytes == 0)
+ break;
+ buf += bytes;
+ len -= bytes;
+ }
+ return total_bytes;
+}
+
static void writebuf(int fd, const char *buf, size_t len)
{
while (len > 0) {
bluesky_store_async_unref(async);
}
+/* Map and return a read-only version of a byte range from a cached file. The
+ * CacheFile object must be locked. */
+BlueSkyRCStr *bluesky_cachefile_map_raw(BlueSkyCacheFile *cachefile,
+ off_t offset, size_t size)
+{
+ cachefile->atime = bluesky_get_current_time();
+
+ /* Easy case: the needed data is already in memory */
+ if (cachefile->addr != NULL && offset + size <= cachefile->len)
+ return bluesky_string_new_from_mmap(cachefile, offset, size);
+
+ int fd = openat(cachefile->log->dirfd, cachefile->filename, O_RDONLY);
+ if (fd < 0) {
+ fprintf(stderr, "Error opening logfile %s: %m\n",
+ cachefile->filename);
+ return NULL;
+ }
+
+ off_t length = lseek(fd, 0, SEEK_END);
+ if (offset + size > length) {
+ close(fd);
+ return NULL;
+ }
+
+ /* File is not mapped in memory. Map the entire file in, then return a
+ * pointer to just the required data. */
+ if (cachefile->addr == NULL) {
+ cachefile->addr = (const char *)mmap(NULL, length, PROT_READ,
+ MAP_SHARED, fd, 0);
+ cachefile->len = length;
+ g_atomic_int_inc(&cachefile->refcount);
+
+ close(fd);
+ return bluesky_string_new_from_mmap(cachefile, offset, size);
+ }
+
+ /* Otherwise, the file was mapped in but doesn't cover the data we need.
+ * This shouldn't happen much, if at all, but if it does just read the data
+ * we need directly from the file. We lose memory-management benefits of
+ * using mmapped data, but otherwise this works. */
+ char *buf = g_malloc(size);
+ size_t actual_size = readbuf(fd, buf, size);
+ close(fd);
+ if (actual_size != size) {
+ g_free(buf);
+ return NULL;
+ } else {
+ return bluesky_string_new(buf, size);
+ }
+}
+
/* The arguments are mostly straightforward. log_dir is -1 for access from the
* journal, and non-negative for access to a cloud log segment. map_data
* should be TRUE for the case that are mapping just the data of an item where
BlueSkyRCStr *bluesky_log_map_object(BlueSkyCloudLog *item, gboolean map_data)
{
BlueSkyFS *fs = item->fs;
- BlueSkyLog *log = fs->log;
BlueSkyCacheFile *map = NULL;
BlueSkyRCStr *str = NULL;
int location = 0;
}
}
- if (map->addr == NULL) {
- int fd = openat(log->dirfd, map->filename, O_RDONLY);
-
- if (fd < 0) {
- fprintf(stderr, "Error opening logfile %s: %m\n", map->filename);
- goto exit2;
- }
-
- off_t length = lseek(fd, 0, SEEK_END);
- map->addr = (const char *)mmap(NULL, length, PROT_READ, MAP_SHARED,
- fd, 0);
- map->len = length;
-
- g_atomic_int_inc(&map->refcount);
-
- close(fd);
- }
-
if (map_data) {
if (location == CLOUDLOG_JOURNAL)
file_offset += sizeof(struct log_header);
file_size = item->data_size;
}
- str = bluesky_string_new_from_mmap(map, file_offset, file_size);
- map->atime = bluesky_get_current_time();
+ str = bluesky_cachefile_map_raw(map, file_offset, file_size);
exit2:
bluesky_cachefile_unref(map);
projects / bluesky.git / commitdiff