X-Git-Url: http://git.vrable.net/?a=blobdiff_plain;f=bluesky%2Flog.c;h=a3acf104239fe56e7a24b5d44c39d94d1aac5dc0;hb=d27b934a06369794d21a3eeaf86c55f942518956;hp=976e32eb47a9bbb6b4420ce8e6759754f5453391;hpb=c0d52390142a72a89aa632172e03a3ec909890ed;p=bluesky.git diff --git a/bluesky/log.c b/bluesky/log.c index 976e32e..a3acf10 100644 --- a/bluesky/log.c +++ b/bluesky/log.c @@ -36,15 +36,17 @@ // 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 struct log_header { uint32_t magic; // HEADER_MAGIC - uint64_t offset; // Starting byte offset of the log header + uint8_t type; // Object type + '0' + uint32_t offset; // Starting byte offset of the log header uint32_t size; // Size of the data item (bytes) + uint64_t inum; // Inode which owns this data, if any BlueSkyCloudID id; // Object identifier } __attribute__((packed)); @@ -103,6 +105,11 @@ 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 +123,10 @@ 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); } @@ -180,9 +191,11 @@ static gpointer log_thread(gpointer d) } header.magic = GUINT32_TO_LE(HEADER_MAGIC); - header.offset = GUINT64_TO_LE(offset); + header.offset = GUINT32_TO_LE(offset); header.size = GUINT32_TO_LE(item->data->len); + header.type = item->type + '0'; header.id = item->id; + header.inum = GUINT64_TO_LE(item->inum); footer.magic = GUINT32_TO_LE(FOOTER_MAGIC); uint32_t crc = BLUESKY_CRC32C_SEED; @@ -278,26 +291,47 @@ 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); @@ -314,6 +348,7 @@ BlueSkyCacheFile *bluesky_cachefile_lookup(BlueSkyFS *fs, BlueSkyLog *log = fs->log; + struct stat statbuf; char logname[64]; int type; @@ -330,10 +365,17 @@ BlueSkyCacheFile *bluesky_cachefile_lookup(BlueSkyFS *fs, g_mutex_lock(log->mmap_lock); map = g_hash_table_lookup(log->mmap_cache, logname); - if (map == NULL) { - /* TODO: stat() call */ + 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); + 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); @@ -347,25 +389,15 @@ BlueSkyCacheFile *bluesky_cachefile_lookup(BlueSkyFS *fs, 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; } @@ -488,16 +520,31 @@ void bluesky_cachefile_gc(BlueSkyFS *fs) g_print(" (fetching)"); g_print("\n"); - if (g_atomic_int_get(&cachefile->refcount) == 0 - && g_atomic_int_get(&cachefile->mapcount) == 0 - && cachefile->type == CLOUDLOG_CLOUD /* FIXME: journals too */) + 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); @@ -514,3 +561,177 @@ void bluesky_cachefile_gc(BlueSkyFS *fs) g_mutex_unlock(fs->log->mmap_lock); } + +/******************************* JOURNAL REPLAY ******************************* + * The journal replay code is used to recover filesystem state after a + * filesystem restart. We first look for the most recent commit record in the + * journal, which indicates the point before which all data in the journal has + * 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) +{ + const struct log_header *header; + const struct log_footer *footer; + + if (offset + sizeof(struct log_header) + sizeof(struct log_footer) > len) + return FALSE; + + header = (const struct log_header *)(buf + offset); + if (GUINT32_FROM_LE(header->magic) != HEADER_MAGIC) + return FALSE; + if (GUINT32_FROM_LE(header->offset) != offset) + return FALSE; + size_t size = GUINT32_FROM_LE(header->size); + + off_t footer_offset = offset + sizeof(struct log_header) + size; + if (footer_offset + sizeof(struct log_footer) > len) + return FALSE; + footer = (const struct log_footer *)(buf + footer_offset); + + if (GUINT32_FROM_LE(footer->magic) != FOOTER_MAGIC) + return FALSE; + + uint32_t crc = crc32c(BLUESKY_CRC32C_SEED, buf + offset, + sizeof(struct log_header) + sizeof(struct log_footer) + + size); + if (crc != BLUESKY_CRC32C_VALIDATOR) { + g_warning("Journal entry failed to validate: CRC %08x != %08x", + crc, BLUESKY_CRC32C_VALIDATOR); + return FALSE; + } + + return TRUE; +} + +/* Scan through a journal segment to extract correctly-written items (those + * that pass sanity checks and have a valid checksum). */ +static void bluesky_replay_scan_journal(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); + 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); + } +} + +void bluesky_replay(BlueSkyFS *fs) +{ + BlueSkyLog *log = fs->log; + 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); + + 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_journal2(fs, &objects, seq_num, + g_mapped_file_get_contents(map), + g_mapped_file_get_length(map)); + g_mapped_file_unref(map); + seq_num++; + } + + while (objects != NULL) { + bluesky_cloudlog_unref((BlueSkyCloudLog *)objects->data); + objects = g_list_delete_link(objects, objects); + } +}