some global stats for bg logger

four obvious ones. have a handy place to do the summarization when the logger
wakes up for its run, avoiding the locks.

4 files changed, 59 insertions, 18 deletions

diff --git a/logger.c b/logger.c
index d9919f2..e549232 100644
--- a/logger.c
+++ b/logger.c
@@ -103,7 +103,7 @@ static void logger_link_q(logger *l) {
 
 /* Completes rendering of log line, copies to subscribed watchers */
 #define LOGGER_PARSE_SCRATCH 4096
-static enum logger_parse_entry_ret logger_parse_entry(logentry *e) {
+static enum logger_parse_entry_ret logger_parse_entry(logentry *e, struct logger_stats *ls) {
     int total = 0;
     int line_size = 0;
     int x;
@@ -140,6 +140,7 @@ static enum logger_parse_entry_ret logger_parse_entry(logentry *e) {
         if (w->failed_flush) {
             L_DEBUG("LOGGER: Fast skipped for watcher [%d] due to failed_flush\n", w->sfd);
             w->skipped++;
+            ls->watcher_skipped++;
         } else if (w->skipped > 0) {
             char *skip_scr = NULL;
             if ((skip_scr = (char *) bipbuf_request(w->buf, line_size + 128)) != NULL) {
@@ -147,15 +148,18 @@ static enum logger_parse_entry_ret logger_parse_entry(logentry *e) {
                 if (total >= 128 || total <= 0) {
                     L_DEBUG("LOGGER: Failed to flatten skipped message into watcher [%d]\n", w->sfd);
                     w->skipped++;
+                    ls->watcher_skipped++;
                 } else {
                     /* These can't fail because bipbuf_request succeeded. */
                     bipbuf_push(w->buf, total + 1);
                     bipbuf_offer(w->buf, (unsigned char *) scratch, line_size);
                     w->skipped = 0;
+                    ls->watcher_sent++;
                 }
             } else {
                 L_DEBUG("LOGGER: Continuing to fast skip for watcher [%d]\n", w->sfd);
                 w->skipped++;
+                ls->watcher_skipped++;
                 w->failed_flush = true;
             }
         } else {
@@ -167,9 +171,12 @@ static enum logger_parse_entry_ret logger_parse_entry(logentry *e) {
                     L_DEBUG("LOGGER: Watcher had no free space for line of size (%d)\n", line_size);
                     w->failed_flush = true;
                     w->skipped++;
+                    ls->watcher_skipped++;
                     break;
                 }
             }
+            if (!w->failed_flush)
+                ls->watcher_sent++;
         }
     }
 
@@ -216,7 +223,7 @@ static void logger_close_watcher(logger_watcher *w) {
 /* Reads a particular worker thread's available bipbuf bytes. Parses each log
  * entry into the watcher buffers.
  */
-static int logger_thread_read(logger *l) {
+static int logger_thread_read(logger *l, struct logger_stats *ls) {
     unsigned int size;
     unsigned int pos = 0;
     unsigned char *data;
@@ -234,7 +241,7 @@ static int logger_thread_read(logger *l) {
     while (pos < size && watcher_count > 0) {
         enum logger_parse_entry_ret ret;
         e = (logentry *) (data + pos);
-        ret = logger_parse_entry(e);
+        ret = logger_parse_entry(e, ls);
         if (ret != LOGGER_PARSE_ENTRY_OK) {
             fprintf(stderr, "LOGGER: Failed to parse log entry\n");
             abort();
@@ -245,6 +252,10 @@ static int logger_thread_read(logger *l) {
 
     pthread_mutex_lock(&l->mutex);
     data = bipbuf_poll(l->buf, size);
+    ls->worker_written += l->written;
+    ls->worker_dropped += l->dropped;
+    l->written = 0;
+    l->dropped = 0;
     pthread_mutex_unlock(&l->mutex);
     if (data == NULL) {
         fprintf(stderr, "LOGGER: unexpectedly couldn't advance buf pointer\n");
@@ -254,18 +265,6 @@ static int logger_thread_read(logger *l) {
     return size; /* maybe the count of objects iterated? */
 }
 
-/* helper function or #define: iterate over loggers */
-/* called with logger_stack_lock held */
-static int logger_iterate(void) {
-    logger *l = NULL;
-    int count = 0;
-    for (l = logger_stack_head; l != NULL; l=l->next) {
-        /* lock logger, call function to manipulate it */
-        count += logger_thread_read(l);
-    }
-    return count;
-}
-
 /* Since the event loop code isn't reusable without a refactor, and we have a
  * limited number of potential watchers, we run our own poll loop.
  * This calls poll() unnecessarily during write flushes, should be possible to
@@ -372,6 +371,15 @@ static int logger_poll_watchers(int force_poll, int watcher) {
     return flushed;
 }
 
+static void logger_thread_sum_stats(struct logger_stats *ls) {
+    STATS_LOCK();
+    stats.log_worker_dropped  += ls->worker_dropped;
+    stats.log_worker_written  += ls->worker_written;
+    stats.log_watcher_skipped += ls->watcher_skipped;
+    stats.log_watcher_sent    += ls->watcher_sent;
+    STATS_UNLOCK();
+}
+
 #define MAX_LOGGER_SLEEP 100000
 #define MIN_LOGGER_SLEEP 0
 
@@ -381,13 +389,19 @@ static void *logger_thread(void *arg) {
     L_DEBUG("LOGGER: Starting logger thread\n");
     while (do_run_logger_thread) {
         int found_logs = 0;
+        logger *l;
+        struct logger_stats ls;
+        memset(&ls, 0, sizeof(struct logger_stats));
         if (to_sleep)
             usleep(to_sleep);
 
         /* Call function to iterate each logger. */
         pthread_mutex_lock(&logger_stack_lock);
-        /* check poll() for current slow watchers */
-        found_logs = logger_iterate();
+        for (l = logger_stack_head; l != NULL; l=l->next) {
+            /* lock logger, call function to manipulate it */
+            found_logs += logger_thread_read(l, &ls);
+        }
+
         logger_poll_watchers(1, WATCHER_ALL);
         pthread_mutex_unlock(&logger_stack_lock);
 
@@ -400,6 +414,7 @@ static void *logger_thread(void *arg) {
             if (to_sleep < 50)
                 to_sleep = MIN_LOGGER_SLEEP;
         }
+        logger_thread_sum_stats(&ls);
     }
 
     return NULL;
@@ -436,6 +451,14 @@ void logger_init(void) {
     if (start_logger_thread() != 0) {
         abort();
     }
+
+    /* This can be removed once the global stats initializer is improved */
+    STATS_LOCK();
+    stats.log_worker_dropped = 0;
+    stats.log_worker_written = 0;
+    stats.log_watcher_skipped = 0;
+    stats.log_watcher_sent = 0;
+    STATS_UNLOCK();
     /* FIXME: temp hack to always add STDERR watcher */
     //logger_add_watcher(NULL, 0);
     return;
@@ -489,6 +512,7 @@ enum logger_ret_type logger_log(logger *l, const enum log_entry_type event, cons
     e = (logentry *) bipbuf_request(buf, (sizeof(logentry) + reqlen));
     if (e == NULL) {
         pthread_mutex_unlock(&l->mutex);
+        l->dropped++;
         return LOGGER_RET_NOSPACE;
     }
     e->gid = gid;
@@ -530,6 +554,7 @@ enum logger_ret_type logger_log(logger *l, const enum log_entry_type event, cons
         pthread_mutex_unlock(&l->mutex);
         return LOGGER_RET_ERR;
     }
+    l->written++;
     L_DEBUG("LOGGER: Requested %d bytes, wrote %d bytes\n", reqlen, total + 1);
 
     pthread_mutex_unlock(&l->mutex);
diff --git a/logger.h b/logger.h
index a244fa1..9d17616 100644
--- a/logger.h
+++ b/logger.h
@@ -64,7 +64,7 @@ typedef struct _logger {
     struct _logger *prev;
     struct _logger *next;
     pthread_mutex_t mutex; /* guard for this + *buf */
-    uint64_t logged; /* entries written to the buffer */
+    uint64_t written; /* entries written to the buffer */
     uint64_t dropped; /* entries dropped */
     uint64_t blocked; /* times blocked instead of dropped */
     uint16_t fetcher_ratio; /* log one out of every N fetches */
@@ -90,6 +90,14 @@ typedef struct  {
     bipbuf_t *buf; /* per-watcher output buffer */
 } logger_watcher;
 
+
+struct logger_stats {
+    uint64_t worker_dropped;
+    uint64_t worker_written;
+    uint64_t watcher_skipped;
+    uint64_t watcher_sent;
+};
+
 extern pthread_key_t logger_key;
 
 /* public functions */
diff --git a/memcached.c b/memcached.c
index 460818b..5447a02 100644
--- a/memcached.c
+++ b/memcached.c
@@ -2656,6 +2656,10 @@ static void server_stats(ADD_STAT add_stats, conn *c) {
     }
     APPEND_STAT("malloc_fails", "%llu",
                 (unsigned long long)stats.malloc_fails);
+    APPEND_STAT("log_worker_dropped", "%llu", (unsigned long long)stats.log_worker_dropped);
+    APPEND_STAT("log_worker_written", "%llu", (unsigned long long)stats.log_worker_written);
+    APPEND_STAT("log_watcher_skipped", "%llu", (unsigned long long)stats.log_watcher_skipped);
+    APPEND_STAT("log_watcher_sent", "%llu", (unsigned long long)stats.log_watcher_sent);
     STATS_UNLOCK();
 }
 
diff --git a/memcached.h b/memcached.h
index 0b39a66..a64bcb8 100644
--- a/memcached.h
+++ b/memcached.h
@@ -299,6 +299,10 @@ struct stats {
     bool          lru_crawler_running; /* crawl in progress */
     uint64_t      lru_maintainer_juggles; /* number of LRU bg pokes */
     uint64_t      time_in_listen_disabled_us;  /* elapsed time in microseconds while server unable to process new connections */
+    uint64_t      log_worker_dropped; /* logs dropped by worker threads */
+    uint64_t      log_worker_written; /* logs written by worker threads */
+    uint64_t      log_watcher_skipped; /* logs watchers missed */
+    uint64_t      log_watcher_sent; /* logs sent to watcher buffers */
     struct timeval maxconns_entered;  /* last time maxconns entered */
 };