#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
+#include <sys/mman.h>
#include "bluesky-private.h"
// 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 << 23)
+#define LOG_SEGMENT_SIZE (1 << 24)
#define HEADER_MAGIC 0x676f4c0a
#define FOOTER_MAGIC 0x2e435243
}
}
+static void log_commit(BlueSkyLog *log)
+{
+ int batchsize = 0;
+
+ if (log->fd < 0)
+ return;
+
+ fdatasync(log->fd);
+ while (log->committed != NULL) {
+ BlueSkyCloudLog *item = (BlueSkyCloudLog *)log->committed->data;
+ g_mutex_lock(item->lock);
+ bluesky_cloudlog_stats_update(item, -1);
+ item->pending_write &= ~CLOUDLOG_JOURNAL;
+ item->location_flags |= CLOUDLOG_JOURNAL;
+ bluesky_cloudlog_stats_update(item, 1);
+ g_cond_signal(item->cond);
+ g_mutex_unlock(item->lock);
+ log->committed = g_slist_delete_link(log->committed, log->committed);
+ bluesky_cloudlog_unref(item);
+ batchsize++;
+ }
+
+ if (bluesky_verbose && batchsize > 1)
+ g_print("Log batch size: %d\n", batchsize);
+}
+
+static gboolean log_open(BlueSkyLog *log)
+{
+ char logname[64];
+
+ if (log->fd >= 0) {
+ log_commit(log);
+ close(log->fd);
+ log->seq_num++;
+ log->fd = -1;
+ }
+
+ while (log->fd < 0) {
+ g_snprintf(logname, sizeof(logname), "log-%08d", log->seq_num);
+ log->fd = openat(log->dirfd, logname, O_CREAT|O_WRONLY|O_EXCL, 0600);
+ if (log->fd < 0 && errno == EEXIST) {
+ fprintf(stderr, "Log file %s already exists...\n", logname);
+ log->seq_num++;
+ continue;
+ } else if (log->fd < 0) {
+ fprintf(stderr, "Error opening logfile %s: %m\n", logname);
+ return FALSE;
+ }
+ }
+
+ if (ftruncate(log->fd, LOG_SEGMENT_SIZE) < 0) {
+ fprintf(stderr, "Unable to truncate logfile %s: %m\n", logname);
+ }
+ fsync(log->fd);
+ fsync(log->dirfd);
+ return TRUE;
+}
+
/* All log writes (at least for a single log) are made by one thread, so we
* don't need to worry about concurrent access to the log file. Log items to
* write are pulled off a queue (and so may be posted by any thread).
{
BlueSkyLog *log = (BlueSkyLog *)d;
- /* If there are multiple log items to write, we may write more than one
- * before calling fsync(). The committed list is used to track all the
- * items that should be marked as committed once that final fsync() is
- * done. */
- GSList *committed = NULL;
-
- int dirfd = open(log->log_directory, O_DIRECTORY);
- if (dirfd < 0) {
- fprintf(stderr, "Unable to open logging directory: %m\n");
- return NULL;
- }
-
while (TRUE) {
if (log->fd < 0) {
- char logfile[64];
- g_snprintf(logfile, sizeof(logfile), "log-%08d", log->seq_num);
- log->fd = openat(dirfd, logfile, O_CREAT|O_WRONLY|O_EXCL, 0600);
- if (log->fd < 0 && errno == EEXIST) {
- fprintf(stderr, "Log file %s already exists...\n", logfile);
- log->seq_num++;
- continue;
- } else if (log->fd < 0) {
- fprintf(stderr, "Error opening logfile %s: %m\n", logfile);
+ if (!log_open(log)) {
return NULL;
}
- fsync(log->fd);
- fsync(dirfd);
}
BlueSkyCloudLog *item
g_mutex_lock(item->lock);
g_assert(item->data != NULL);
+ /* The item may have already been written to the journal... */
if ((item->location_flags | item->pending_write) & CLOUDLOG_JOURNAL) {
g_mutex_unlock(item->lock);
bluesky_cloudlog_unref(item);
+ g_atomic_int_add(&item->data_lock_count, -1);
continue;
}
+ bluesky_cloudlog_stats_update(item, -1);
item->pending_write |= CLOUDLOG_JOURNAL;
+ bluesky_cloudlog_stats_update(item, 1);
- off_t logsize = lseek(log->fd, 0, SEEK_CUR);
struct log_header header;
struct log_footer footer;
+ size_t size = sizeof(header) + sizeof(footer) + item->data->len;
+ off_t offset = 0;
+ if (log->fd >= 0)
+ offset = lseek(log->fd, 0, SEEK_CUR);
+
+ /* Check whether the item would overflow the allocated journal size.
+ * If so, start a new log segment. We only allow oversized log
+ * segments if they contain a single log entry. */
+ if (offset + size >= LOG_SEGMENT_SIZE && offset > 0) {
+ log_open(log);
+ offset = 0;
+ }
header.magic = GUINT32_TO_LE(HEADER_MAGIC);
- header.offset = GUINT64_TO_LE(logsize);
+ header.offset = GUINT64_TO_LE(offset);
header.size = GUINT32_TO_LE(item->data->len);
header.id = item->id;
footer.magic = GUINT32_TO_LE(FOOTER_MAGIC);
writebuf(log->fd, (const char *)&footer, sizeof(footer));
item->log_seq = log->seq_num;
- item->log_offset = logsize + sizeof(header);
+ item->log_offset = offset + sizeof(header);
item->log_size = item->data->len;
- logsize += sizeof(header) + sizeof(footer) + item->data->len;
+ offset += sizeof(header) + sizeof(footer) + item->data->len;
- committed = g_slist_prepend(committed, item);
+ log->committed = g_slist_prepend(log->committed, item);
+ g_atomic_int_add(&item->data_lock_count, -1);
g_mutex_unlock(item->lock);
- /* Force an fsync either if we will be closing this log segment and
- * opening a new file, or if there are no other log items currently
- * waiting to be written. */
-
- if (logsize >= LOG_SEGMENT_SIZE
- || g_async_queue_length(log->queue) <= 0)
- {
- int batchsize = 0;
- fdatasync(log->fd);
- while (committed != NULL) {
- item = (BlueSkyCloudLog *)committed->data;
- g_mutex_lock(item->lock);
- item->pending_write &= ~CLOUDLOG_JOURNAL;
- item->location_flags |= CLOUDLOG_JOURNAL;
- g_cond_signal(item->cond);
- g_mutex_unlock(item->lock);
- committed = g_slist_delete_link(committed, committed);
- batchsize++;
- }
- /* if (batchsize > 1)
- g_print("Log batch size: %d\n", batchsize); */
- }
-
- if (logsize < 0 || logsize >= LOG_SEGMENT_SIZE) {
- close(log->fd);
- log->fd = -1;
- log->seq_num++;
- }
+ /* Force an if there are no other log items currently waiting to be
+ * written. */
+ if (g_async_queue_length(log->queue) <= 0)
+ log_commit(log);
}
return NULL;
log->fd = -1;
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->dirfd = open(log->log_directory, O_DIRECTORY);
+ if (log->dirfd < 0) {
+ fprintf(stderr, "Unable to open logging directory: %m\n");
+ return NULL;
+ }
g_thread_create(log_thread, log, FALSE, NULL);
void bluesky_log_item_submit(BlueSkyCloudLog *item, BlueSkyLog *log)
{
bluesky_cloudlog_ref(item);
+ g_atomic_int_add(&item->data_lock_count, 1);
g_async_queue_push(log->queue, item);
}
log_items = g_list_delete_link(log_items, log_items);
}
}
+
+/* Memory-map the given log object into memory (read-only) and return a pointer
+ * to it. */
+static int page_size = 0;
+
+BlueSkyRCStr *bluesky_log_map_object(BlueSkyLog *log,
+ int log_seq, int log_offset, int log_size)
+{
+ if (page_size == 0) {
+ page_size = getpagesize();
+ }
+
+ BlueSkyMmap *map;
+ g_mutex_lock(log->mmap_lock);
+ map = g_hash_table_lookup(log->mmap_cache, GINT_TO_POINTER(log_seq));
+
+ if (map == NULL) {
+ char logname[64];
+ g_snprintf(logname, sizeof(logname), "log-%08d", log_seq);
+ int fd = openat(log->dirfd, logname, O_RDONLY);
+
+ if (fd < 0) {
+ fprintf(stderr, "Error opening logfile %s: %m\n", logname);
+ g_mutex_unlock(log->mmap_lock);
+ return NULL;
+ }
+
+ map = g_new0(BlueSkyMmap, 1);
+
+ off_t length = lseek(fd, 0, SEEK_END);
+ map->log_seq = log_seq;
+ map->addr = (const char *)mmap(NULL, length, PROT_READ, MAP_SHARED,
+ fd, 0);
+ map->len = length;
+ map->log = log;
+ g_atomic_int_set(&map->refcount, 0);
+
+ g_hash_table_insert(log->mmap_cache, GINT_TO_POINTER(log_seq), map);
+
+ g_print("Mapped log segment %d...\n", log_seq);
+
+ close(fd);
+ }
+
+ g_mutex_unlock(log->mmap_lock);
+
+ return bluesky_string_new_from_mmap(map, log_offset, log_size);
+}
+
+void bluesky_mmap_unref(BlueSkyMmap *mmap)
+{
+ if (mmap == NULL)
+ return;
+
+ if (g_atomic_int_dec_and_test(&mmap->refcount)) {
+ /* There is a potential race condition here: the BlueSkyLog contains a
+ * hash table of currently-existing BlueSkyMmap objects, which does not
+ * hold a reference. Some other thread might grab a new reference to
+ * this object after reading it from the hash table. So, before
+ * destruction we need to grab the lock for the hash table, then check
+ * the reference count again. If it is still zero, we can proceed with
+ * object destruction. */
+ BlueSkyLog *log = mmap->log;
+ g_mutex_lock(log->mmap_lock);
+ if (g_atomic_int_get(&mmap->refcount) > 0) {
+ g_mutex_unlock(log->mmap_lock);
+ return;
+ }
+
+ g_hash_table_remove(log->mmap_cache, GINT_TO_POINTER(mmap->log_seq));
+ munmap((void *)mmap->addr, mmap->len);
+ g_free(mmap);
+ g_mutex_unlock(log->mmap_lock);
+ }
+}
+
projects / bluesky.git / blobdiff