osmocom
/
libosmocore
mirror of https://gerrit.osmocom.org/libosmocore
11
0
Fork 0
Code Issues Releases Wiki Activity

logging: Change stderr + file target to use non-blocking write 

So far, we used blocking, buffered fwrite() to write to stderr
and file targets.  This causes problems if there are [slow] consumers
causing delays, such as gnome-terminal (when the program is started
interactively) or systemd/journald (where we observe 64..128ms blocks on
stderr).

This patch introduces stderr/file based logging via write_queue
and osmo_select_main(), i.e. switch from glibc-buffered, blocking
to internally buffered, non-blocking writes.

* when osmo_stderr_target is created via application.c, we create it
  in blocking stream mode for backwards compatibility, particularly
  for [smaller] programs that don't use osmo_select_main()

* when the VTY code encounters 'log stderr' or 'log file FILENAME',
  we switch that respective target to non-blocking write-queue mode,
  as this means the application is in fact using osmo_select_main()

* The config file can now state 'log stderr blocking-io' or
  'log file FILENAME blocking-io' to explicitly enforce using blocking
  stream based I/O

* The application can at any time use API functions to switch either way

Closes: OS#4311
Change-Id: Ia58fd78535c41b3da3aeb7733aadc785ace610da
This commit is contained in:
Harald Welte 2020-09-26 21:45:16 +02:00
parent 8db64ee810
commit b72867f0e6
4 changed files with 313 additions and 22 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
include/osmocom/core/logging.h
View File

@ -297,8 +297,11 @@ struct log_target {
union {
struct {
/* direct, blocking output via stdio */
FILE *out;
const char *fname;
/* indirect output via write_queue and osmo_select_main() */
struct osmo_wqueue *wqueue;
} tgt_file;
struct {
@ -408,6 +411,8 @@ struct log_target *log_target_create_gsmtap(const char *host, uint16_t port,
struct log_target *log_target_create_systemd(bool raw);
void log_target_systemd_set_raw(struct log_target *target, bool raw);
int log_target_file_reopen(struct log_target *tgt);
int log_target_file_switch_to_stream(struct log_target *tgt);
int log_target_file_switch_to_wqueue(struct log_target *tgt);
int log_targets_reopen(void);
void log_add_target(struct log_target *target);

297
src/logging.c
View File

@ -35,6 +35,7 @@
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#ifdef HAVE_STRINGS_H
#include <strings.h>
@ -57,6 +58,9 @@
#include <time.h>
#include <sys/time.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <errno.h>
#include <pthread.h>
@ -65,12 +69,17 @@
#include <osmocom/core/logging.h>
#include <osmocom/core/timer.h>
#include <osmocom/core/thread.h>
#include <osmocom/core/select.h>
#include <osmocom/core/write_queue.h>
#include <osmocom/vty/logging.h> /* for LOGGING_STR. */
/* maximum length of the log string of a single log event (typically line) */
#define MAX_LOG_SIZE 4096
/* maximum number of log statements we queue in file/stderr target write queue */
#define LOG_WQUEUE_LEN 1024
osmo_static_assert(_LOG_CTX_COUNT <= ARRAY_SIZE(((struct log_context*)NULL)->ctx),
enum_logging_ctx_items_fit_in_struct_log_context);
osmo_static_assert(_LOG_FLT_COUNT <= ARRAY_SIZE(((struct log_target*)NULL)->filter_data),
@ -904,11 +913,32 @@ void log_set_category_filter(struct log_target *target, int category,
}
#if (!EMBEDDED)
static void _file_output_stream(struct log_target *target, unsigned int level,
const char *log)
{
OSMO_ASSERT(target->tgt_file.out);
fputs(log, target->tgt_file.out);
fflush(target->tgt_file.out);
}
/* output via non-blocking write_queue, doing internal buffering */
static void _file_output(struct log_target *target, unsigned int level,
const char *log)
{
fprintf(target->tgt_file.out, "%s", log);
fflush(target->tgt_file.out);
int len = strlen(log);
struct msgb *msg;
OSMO_ASSERT(target->tgt_file.wqueue);
msg = msgb_alloc_c(target->tgt_file.wqueue, len, "log_file_msg");
if (!msg)
return;
/* we simply enqueue the log message to a write queue here, to avoid any blocking
* writes on the output file. The write queue will tell us once the file is writable
* and call _file_wq_write_cb() */
memcpy(msg->data, log, len);
msgb_put(msg, len);
osmo_wqueue_enqueue_quiet(target->tgt_file.wqueue, msg);
}
#endif
@ -972,7 +1002,7 @@ struct log_target *log_target_create_stderr(void)
target->type = LOG_TGT_TYPE_STDERR;
target->tgt_file.out = stderr;
target->output = _file_output;
target->output = _file_output_stream;
return target;
#else
return NULL;
@ -980,11 +1010,28 @@ struct log_target *log_target_create_stderr(void)
}
#if (!EMBEDDED)
/*! Create a new file-based log target
/* write-queue tells us we should write another msgb (log line) to the output fd */
static int _file_wq_write_cb(struct osmo_fd *ofd, struct msgb *msg)
{
int rc;
rc = write(ofd->fd, msgb_data(msg), msgb_length(msg));
if (rc < 0)
return rc;
if (rc != msgb_length(msg)) {
/* pull the number of bytes we have already written */
msgb_pull(msg, rc);
/* ask write_queue to re-insert the msgb at the head of the queue */
return -EAGAIN;
}
return 0;
}
/*! Create a new file-based log target using buffered, blocking stream output
* \param[in] fname File name of the new log file
* \returns Log target in case of success, NULL otherwise
*/
struct log_target *log_target_create_file(const char *fname)
struct log_target *log_target_create_file_stream(const char *fname)
{
struct log_target *target;
@ -998,9 +1045,193 @@ struct log_target *log_target_create_file(const char *fname)
log_target_destroy(target);
return NULL;
}
target->output = _file_output_stream;
target->tgt_file.fname = talloc_strdup(target, fname);
return target;
}
/*! switch from non-blocking/write-queue to blocking + buffered stream output
* \param[in] target log target which we should switch
* \return 0 on success; 1 if already switched before; negative on error */
int log_target_file_switch_to_stream(struct log_target *target)
{
struct osmo_wqueue *wq;
const char *name;
if (!target)
return -ENODEV;
/* this only works for file/stderr targets */
switch (target->type) {
case LOG_TGT_TYPE_FILE:
name = target->tgt_file.fname;
break;
case LOG_TGT_TYPE_STDERR:
name = "stderr";
break;
default:
return -EINVAL;
}
if (target->tgt_file.out) {
/* target has already been switched over */
return 1;
}
LOGP(DLGLOBAL, LOGL_INFO, "Switching log target '%s' to blocking stream I/O\n", name);
wq = target->tgt_file.wqueue;
OSMO_ASSERT(wq);
/* re-open output as stream */
if (target->type == LOG_TGT_TYPE_STDERR)
target->tgt_file.out = stderr;
else
target->tgt_file.out = fopen(target->tgt_file.fname, "a");
if (!target->tgt_file.out) {
LOGP(DLGLOBAL, LOGL_ERROR, "Cannot open log target '%s' as blocking stream I/O: %s\n",
name, strerror(errno));
return -EIO;
}
/* synchronously write anything left in the queue */
while (!llist_empty(&wq->msg_queue)) {
struct msgb *msg = msgb_dequeue(&wq->msg_queue);
fwrite(msgb_data(msg), msgb_length(msg), 1, target->tgt_file.out);
msgb_free(msg);
}
/* now that everything succeeded, we can finally close the old output fd */
if (target->type == LOG_TGT_TYPE_FILE) {
osmo_fd_unregister(&wq->bfd);
close(wq->bfd.fd);
}
/* release the queue itself */
talloc_free(wq);
target->tgt_file.wqueue = NULL;
target->output = _file_output_stream;
target->raw_output = NULL;
return 0;
}
/*! switch from blocking + buffered file output to non-blocking write-queue based output.
* \param[in] target log target which we should switch
* \return 0 on success; 1 if already switched before; negative on error */
int log_target_file_switch_to_wqueue(struct log_target *target)
{
struct osmo_wqueue *wq;
const char *name;
int rc;
if (!target)
return -ENODEV;
/* this only works for file/stderr targets */
switch (target->type) {
case LOG_TGT_TYPE_FILE:
name = target->tgt_file.fname;
break;
case LOG_TGT_TYPE_STDERR:
name = "stderr";
break;
default:
return -EINVAL;
}
if (!target->tgt_file.out) {
/* target has already been switched over */
return 1;
}
LOGP(DLGLOBAL, LOGL_INFO, "Switching log target '%s' to non-blocking I/O\n", name);
/* we create a ~640kB sized talloc pool within the write-queue to ensure individual
* log lines (stored as msgbs) will not put result in malloc() calls, and also to
* reduce the OOM probability within logging, as the pool is already allocated */
wq = talloc_pooled_object(target, struct osmo_wqueue, LOG_WQUEUE_LEN,
LOG_WQUEUE_LEN*(sizeof(struct msgb)+512));
if (!wq)
return -ENOMEM;
osmo_wqueue_init(wq, LOG_WQUEUE_LEN);
fflush(target->tgt_file.out);
if (target->type == LOG_TGT_TYPE_FILE) {
rc = open(target->tgt_file.fname, O_WRONLY|O_APPEND|O_CREAT|O_NONBLOCK, 0660);
if (rc < 0) {
LOGP(DLGLOBAL, LOGL_ERROR, "Cannot open log target '%s' as non-blocking I/O: %s\n",
name, strerror(errno));
talloc_free(wq);
return -errno;
}
} else {
rc = STDERR_FILENO;
}
wq->bfd.fd = rc;
wq->bfd.when = OSMO_FD_WRITE;
wq->write_cb = _file_wq_write_cb;
rc = osmo_fd_register(&wq->bfd);
if (rc < 0) {
talloc_free(wq);
return -EIO;
}
target->tgt_file.wqueue = wq;
target->output = _file_output;
/* now that everything succeeded, we can finally close the old output stream */
if (target->type == LOG_TGT_TYPE_FILE)
fclose(target->tgt_file.out);
target->tgt_file.out = NULL;
return 0;
}
/*! Create a new file-based log target using non-blocking write_queue
* \param[in] fname File name of the new log file
* \returns Log target in case of success, NULL otherwise
*/
struct log_target *log_target_create_file(const char *fname)
{
struct log_target *target;
struct osmo_wqueue *wq;
int rc;
target = log_target_create();
if (!target)
return NULL;
target->type = LOG_TGT_TYPE_FILE;
/* we create a ~640kB sized talloc pool within the write-queue to ensure individual
* log lines (stored as msgbs) will not put result in malloc() calls, and also to
* reduce the OOM probability within logging, as the pool is already allocated */
wq = talloc_pooled_object(target, struct osmo_wqueue, LOG_WQUEUE_LEN,
LOG_WQUEUE_LEN*(sizeof(struct msgb)+512));
if (!wq) {
log_target_destroy(target);
return NULL;
}
osmo_wqueue_init(wq, LOG_WQUEUE_LEN);
wq->bfd.fd = open(fname, O_WRONLY|O_APPEND|O_CREAT|O_NONBLOCK, 0660);
if (wq->bfd.fd < 0) {
talloc_free(wq);
log_target_destroy(target);
return NULL;
}
wq->bfd.when = OSMO_FD_WRITE;
wq->write_cb = _file_wq_write_cb;
rc = osmo_fd_register(&wq->bfd);
if (rc < 0) {
talloc_free(wq);
log_target_destroy(target);
return NULL;
}
target->tgt_file.wqueue = wq;
target->output = _file_output;
target->tgt_file.fname = talloc_strdup(target, fname);
return target;
@ -1040,17 +1271,33 @@ struct log_target *log_target_find(int type, const char *fname)
* \param[in] target log target to unregister, close and delete */
void log_target_destroy(struct log_target *target)
{
/* just in case, to make sure we don't have any references */
log_del_target(target);
#if (!EMBEDDED)
struct osmo_wqueue *wq;
switch (target->type) {
case LOG_TGT_TYPE_FILE:
if (target->tgt_file.out == NULL)
break;
fclose(target->tgt_file.out);
target->tgt_file.out = NULL;
case LOG_TGT_TYPE_STDERR:
if (target->tgt_file.out) {
if (target->type == LOG_TGT_TYPE_FILE)
fclose(target->tgt_file.out);
target->tgt_file.out = NULL;
}
wq = target->tgt_file.wqueue;
if (wq) {
if (wq->bfd.fd >= 0) {
if (target->type == LOG_TGT_TYPE_FILE)
close(wq->bfd.fd);
wq->bfd.fd = -1;
}
osmo_fd_unregister(&wq->bfd);
osmo_wqueue_clear(wq);
talloc_free(wq);
target->tgt_file.wqueue = NULL;
}
talloc_free((void *)target->tgt_file.fname);
target->tgt_file.fname = NULL;
break;
#ifdef HAVE_SYSLOG_H
case LOG_TGT_TYPE_SYSLOG:
@ -1071,13 +1318,33 @@ void log_target_destroy(struct log_target *target)
* \returns 0 in case of success; negative otherwise */
int log_target_file_reopen(struct log_target *target)
{
fclose(target->tgt_file.out);
struct osmo_wqueue *wq;
int rc;
target->tgt_file.out = fopen(target->tgt_file.fname, "a");
if (!target->tgt_file.out)
return -errno;
OSMO_ASSERT(target->type == LOG_TGT_TYPE_FILE || target->type == LOG_TGT_TYPE_STDERR);
OSMO_ASSERT(target->tgt_file.out || target->tgt_file.wqueue);
/* we assume target->output already to be set */
if (target->tgt_file.out) {
fclose(target->tgt_file.out);
target->tgt_file.out = fopen(target->tgt_file.fname, "a");
if (!target->tgt_file.out)
return -errno;
} else {
wq = target->tgt_file.wqueue;
osmo_fd_unregister(&wq->bfd);
if (wq->bfd.fd >= 0) {
close(wq->bfd.fd);
wq->bfd.fd = -1;
}
rc = open(target->tgt_file.fname, O_WRONLY|O_APPEND|O_CREAT|O_NONBLOCK, 0660);
if (rc < 0)
return -errno;
wq->bfd.fd = rc;
rc = osmo_fd_register(&wq->bfd);
if (rc < 0)
return rc;
}
return 0;
}

32
src/vty/logging_vty.c
View File

@ -835,8 +835,9 @@ DEFUN(cfg_log_gsmtap, cfg_log_gsmtap_cmd,
}
DEFUN(cfg_log_stderr, cfg_log_stderr_cmd,
"log stderr",
LOG_STR "Logging via STDERR of the process\n")
"log stderr [blocking-io]",
LOG_STR "Logging via STDERR of the process\n"
"Use blocking, synchronous I/O\n")
{
struct log_target *tgt;
@ -852,6 +853,11 @@ DEFUN(cfg_log_stderr, cfg_log_stderr_cmd,
log_add_target(tgt);
}
if (argc > 0 && !strcmp(argv[0], "blocking-io"))
log_target_file_switch_to_stream(tgt);
else
log_target_file_switch_to_wqueue(tgt);
vty->index = tgt;
vty->node = CFG_LOG_NODE;
@ -878,8 +884,9 @@ DEFUN(cfg_no_log_stderr, cfg_no_log_stderr_cmd,
}
DEFUN(cfg_log_file, cfg_log_file_cmd,
"log file .FILENAME",
LOG_STR "Logging to text file\n" "Filename\n")
"log file FILENAME [blocking-io]",
LOG_STR "Logging to text file\n" "Filename\n"
"Use blocking, synchronous I/O\n")
{
const char *fname = argv[0];
struct log_target *tgt;
@ -896,6 +903,11 @@ DEFUN(cfg_log_file, cfg_log_file_cmd,
log_add_target(tgt);
}
if (argc > 1 && !strcmp(argv[1], "blocking-io"))
log_target_file_switch_to_stream(tgt);
else
log_target_file_switch_to_wqueue(tgt);
vty->index = tgt;
vty->node = CFG_LOG_NODE;
@ -904,7 +916,7 @@ DEFUN(cfg_log_file, cfg_log_file_cmd,
DEFUN(cfg_no_log_file, cfg_no_log_file_cmd,
"no log file .FILENAME",
"no log file FILENAME",
NO_STR LOG_STR "Logging to text file\n" "Filename\n")
{
const char *fname = argv[0];
@ -979,7 +991,10 @@ static int config_write_log_single(struct vty *vty, struct log_target *tgt)
return 1;
break;
case LOG_TGT_TYPE_STDERR:
vty_out(vty, "log stderr%s", VTY_NEWLINE);
if (tgt->tgt_file.wqueue)
vty_out(vty, "log stderr%s", VTY_NEWLINE);
else
vty_out(vty, "log stderr blocking-io%s", VTY_NEWLINE);
break;
case LOG_TGT_TYPE_SYSLOG:
#ifdef HAVE_SYSLOG_H
@ -990,7 +1005,10 @@ static int config_write_log_single(struct vty *vty, struct log_target *tgt)
#endif
break;
case LOG_TGT_TYPE_FILE:
vty_out(vty, "log file %s%s", tgt->tgt_file.fname, VTY_NEWLINE);
if (tgt->tgt_file.wqueue)
vty_out(vty, "log file %s%s", tgt->tgt_file.fname, VTY_NEWLINE);
else
vty_out(vty, "log file %s blocking-io%s", tgt->tgt_file.fname, VTY_NEWLINE);
break;
case LOG_TGT_TYPE_STRRB:
vty_out(vty, "log alarms %zu%s",

1
tests/logging/logging_vty_test.c
View File

@ -254,6 +254,7 @@ int main(int argc, char **argv)
log_set_print_category_hex(osmo_stderr_target, 0);
log_set_print_level(osmo_stderr_target, 1);
log_set_print_filename2(osmo_stderr_target, LOG_FILENAME_NONE);
log_target_file_switch_to_wqueue(osmo_stderr_target);
if (cmdline_config.config_file) {
rc = vty_read_config_file(cmdline_config.config_file, NULL);