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ctdb-common: Log a count of dropped messages with non-blocking logging

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The non-blocking logging variants can currently silently drop messages
when the socket queue fills.

In this case, count the number of dropped messages and attempt to log
a message about dropped log messages when the next message is logged.

Signed-off-by: Martin Schwenke <martin@meltin.net>
Reviewed-by: Amitay Isaacs <amitay@gmail.com>
This commit is contained in:
Martin Schwenke 2017-06-01 21:13:58 +10:00 committed by Martin Schwenke
parent 323291a46e
commit d79c601fde
1 changed files with 53 additions and 5 deletions
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58
ctdb/common/logging.c
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@ -239,6 +239,7 @@ struct syslog_log_state {
/* RFC3164 says: The total length of the packet MUST be 1024
bytes or less. */
char buffer[1024];
unsigned int dropped_count;
};
/* Format messages as per RFC3164
@ -307,19 +308,66 @@ static void syslog_log(void *private_data, int level, const char *msg)
syslog(debug_level_to_priority(level), "%s", msg);
}
static void syslog_log_sock(void *private_data, int level, const char *msg)
static int syslog_log_sock_maybe(struct syslog_log_state *state,
int level, const char *msg)
{
struct syslog_log_state *state = talloc_get_type_abort(
private_data, struct syslog_log_state);
int n;
ssize_t ret;
n = state->format(level, state, msg, state->buffer,
sizeof(state->buffer));
if (n == -1) {
return;
return E2BIG;
}
sys_write_v(state->fd, state->buffer, n);
do {
ret = write(state->fd, state->buffer, n);
} while (ret == -1 && errno == EINTR);
if (ret == -1) {
return errno;
}
return 0;
}
static void syslog_log_sock(void *private_data, int level, const char *msg)
{
struct syslog_log_state *state = talloc_get_type_abort(
private_data, struct syslog_log_state);
int ret;
if (state->dropped_count > 0) {
char t[64] = { 0 };
snprintf(t, sizeof(t),
"[Dropped %u log messages]\n",
state->dropped_count);
t[sizeof(t)-1] = '\0';
ret = syslog_log_sock_maybe(state, level, t);
if (ret == EAGAIN || ret == EWOULDBLOCK) {
state->dropped_count++;
/*
* If above failed then actually drop the
* message that would be logged below, since
* it would have been dropped anyway and it is
* also likely to fail. Falling through and
* attempting to log the message also means
* that the dropped message count will be
* logged out of order.
*/
return;
}
if (ret != 0) {
/* Silent failure on any other error */
return;
}
state->dropped_count = 0;
}
ret = syslog_log_sock_maybe(state, level, msg);
if (ret == EAGAIN || ret == EWOULDBLOCK) {
state->dropped_count++;
}
}
static int syslog_log_setup_syslog(TALLOC_CTX *mem_ctx, const char *app_name)