Revert "Revert "logger: introduce lazy/hybrid approach to early logging""

This reverts commit 064c096da525adedf0766d0b91de16b011841676.

Change-Id: I2cf0fecf8437766fe774a4f702622e3d8c0d0109

diff --git a/configs/dlog.conf b/configs/dlog.conf
index b150cfc..524b39a 100644 (file)
--- a/configs/dlog.conf
+++ b/configs/dlog.conf
@@ -74,6 +74,14 @@ handle_kmsg=1
 # for continuous dlogutil instances.
 epoll_time_ms=1000
 
+# How long after start the daemon works in "lazy" mode, which means that it
+# wakes up exactly after specified time (unlike regular polling, where it
+# might wake up immediately if logs are available). This reduces the overhead
+# for waking up, but can result in log loss under heavy load. Use -1 as the
+# total time to keep the daemon in the lazy mode permanently.
+lazy_polling_total_ms=-1
+lazy_polling_sleep_ms=1000
+
 # Syslog handling currently disabled in the daemon - not needed in Tizen.
 #dlog_logger_conf_syslog=dlogutil -b syslog -r 256 -n 1 -f /var/log/dlog/syslog -v recv_realtime
 

diff --git a/src/logger/logger.c b/src/logger/logger.c
index 7487836..ea29622 100644 (file)
--- a/src/logger/logger.c
+++ b/src/logger/logger.c
@@ -58,6 +58,11 @@ static struct {
 
 static const int DEFAULT_EPOLL_TIME_MS = 1000;
 
+static const int DEFAULT_LAZY_POLLING_TOTAL_MS = 0;
+static const int DEFAULT_LAZY_POLLING_SLEEP_MS = 1000;
+
+static const int MS_TO_US = 1000;
+
 /**
  * @brief Parse permissions
  * @details Parse a string representation of permissions to the internal integral one
@@ -1764,6 +1769,9 @@ static int logger_create(struct logger_config_data *data, struct logger *l)
                return -errno;
        l->epolltime = data->epoll_time;
 
+       l->lazy_polling_total = data->lazy_polling_total;
+       l->lazy_polling_sleep = data->lazy_polling_sleep;
+
        l->buf_params = data->buf_params;
 
        for (log_id_t id = 0; id < LOG_ID_MAX; id++)
@@ -1935,12 +1943,20 @@ static int do_logger(struct logger* server)
        if (r < 0)
                return r;
 
+       bool use_lazy_polling = true;
        while (g_logger_run) {
                clock_gettime(CLOCK_MONOTONIC, &server->now);
 
+               if (server->lazy_polling_total >= 0) {
+                       server->lazy_polling_total -= server->lazy_polling_sleep;
+                       use_lazy_polling = (server->lazy_polling_total >= 0);
+               }
+               if (use_lazy_polling)
+                       usleep(MS_TO_US * server->lazy_polling_sleep);
+
                ensure_epoll_size(&events, &events_size, server->epollcnt);
 
-               int nfds = epoll_wait(server->epollfd, events, events_size, server->epolltime);
+               int nfds = epoll_wait(server->epollfd, events, events_size, server->epolltime * !use_lazy_polling);
                if (nfds < 0 && errno == EINTR) // TODO: This is *almost* TEMP_FAILURE_RETRY. Is it equivalent?
                        continue;
 
@@ -2105,6 +2121,8 @@ int prepare_config_data(struct logger_config_data *data)
        }
 
        data->epoll_time = log_config_get_int(&conf, "epoll_time_ms", DEFAULT_EPOLL_TIME_MS);
+       data->lazy_polling_total = log_config_get_int(&conf, "lazy_polling_total_ms", DEFAULT_LAZY_POLLING_TOTAL_MS);
+       data->lazy_polling_sleep = log_config_get_int(&conf, "lazy_polling_sleep_ms", DEFAULT_LAZY_POLLING_SLEEP_MS);
 
        memset(data->is_buffer_enabled, 0, sizeof(data->is_buffer_enabled));
        if (!strcmp(backend, "pipe")) {

diff --git a/src/logger/logger_internal.h b/src/logger/logger_internal.h
index c32dd62..9a0bbbb 100644 (file)
--- a/src/logger/logger_internal.h
+++ b/src/logger/logger_internal.h
@@ -205,6 +205,8 @@ struct logger {
        int                 epollfd;
        unsigned            epollcnt;
        int                 epolltime;
+       int                 lazy_polling_total;
+       int                 lazy_polling_sleep;
        list_head           writers;
        list_head           extra_readers;
        struct log_buffer*  buffers[LOG_ID_MAX];
@@ -228,6 +230,8 @@ struct buffer_config_data {
 struct logger_config_data {
        struct buf_params buf_params;
        list_head logfile_configs;
+       int lazy_polling_total;
+       int lazy_polling_sleep;
        int epoll_time;
        int is_buffer_enabled[LOG_ID_MAX];
        struct buffer_config_data buffers[LOG_ID_MAX];