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authorHarald Welte <laforge@osmocom.org>2020-09-26 21:45:16 +0200
committerHarald Welte <laforge@osmocom.org>2020-12-30 17:24:05 +0100
commit118292632b0eeda78c6e7ffa25204d2e2da70965 (patch)
tree637473e0576f6d5bd9b891d5241bd3297d318ff6
parentfdea03b40859057fb85014ace8cdb65e57c2b373 (diff)
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
-rw-r--r--include/osmocom/core/logging.h5
-rw-r--r--src/logging.c296
-rw-r--r--src/vty/logging_vty.c32
-rw-r--r--tests/logging/logging_vty_test.c1
4 files changed, 313 insertions, 21 deletions
diff --git a/include/osmocom/core/logging.h b/include/osmocom/core/logging.h
index c7f89dea..1b35daaf 100644
--- a/include/osmocom/core/logging.h
+++ b/include/osmocom/core/logging.h
@@ -293,8 +293,11 @@ 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 {
@@ -403,6 +406,8 @@ 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);
diff --git a/src/logging.c b/src/logging.c
index 01a00da3..57238fb4 100644
--- a/src/logging.c
+++ b/src/logging.c
@@ -35,6 +35,7 @@
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
+#include <unistd.h>
#ifdef HAVE_STRINGS_H
#include <strings.h>
@@ -46,6 +47,9 @@
#include <time.h>
#include <sys/time.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
#include <errno.h>
#include <pthread.h>
@@ -53,12 +57,17 @@
#include <osmocom/core/utils.h>
#include <osmocom/core/logging.h>
#include <osmocom/core/timer.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),
@@ -860,12 +869,33 @@ void log_set_category_filter(struct log_target *target, int category,
}
#if (!EMBEDDED)
-static void _file_output(struct log_target *target, unsigned int level,
+static void _file_output_stream(struct log_target *target, unsigned int level,
const char *log)
{
+ OSMO_ASSERT(target->tgt_file.out);
fprintf(target->tgt_file.out, "%s", log);
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)
+{
+ 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
/*! Create a new log target skeleton
@@ -927,7 +957,7 @@ 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;
@@ -935,11 +965,28 @@ 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;
@@ -953,9 +1000,194 @@ 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);
+
+ /* close the write queue file descriptor */
+ 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 block 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;
@@ -995,17 +1227,33 @@ 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:
@@ -1026,13 +1274,33 @@ 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;
}
diff --git a/src/vty/logging_vty.c b/src/vty/logging_vty.c
index 02823504..bd7fd34a 100644
--- a/src/vty/logging_vty.c
+++ b/src/vty/logging_vty.c
@@ -819,8 +819,9 @@ 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;
@@ -836,6 +837,11 @@ 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;
@@ -862,8 +868,9 @@ 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;
@@ -880,6 +887,11 @@ 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;
@@ -888,7 +900,7 @@ 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];
@@ -963,7 +975,10 @@ 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
@@ -974,7 +989,10 @@ 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",
diff --git a/tests/logging/logging_vty_test.c b/tests/logging/logging_vty_test.c
index e7019f61..078555e9 100644
--- a/tests/logging/logging_vty_test.c
+++ b/tests/logging/logging_vty_test.c
@@ -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);