logger: Added logger_queue_limit to the configuration options.

All log messages go to a queue serviced by a single thread
which does all the IO.  This setting controls how big that
queue can get (and therefore how much memory is allocated)
before new messages are discarded. The default is 1000.
Should something go bezerk and log tons of messages in a tight
loop, this will prevent memory escalation.

When the limit is reached, a WARNING is logged to that effect
and messages are discarded until the queue is empty again.  At
that time another WARNING will be logged with the count of
discarded messages.  There's no "low water mark" for this queue
because the logger thread empties the entire queue and processes it
in 1 batch before going back and waiting on the queue again.
Implementing a low water mark would mean additional locking as
the thread processes each message and it's not worth it.

A "test" was added to test_logger.c but since the outcome is
non-deterministic, it's really just a cli command, not a unit
test.

Change-Id: Ib4520c95e1ca5325dbf584c7989ce391649836d1

CHANGES

@@ -31,6 +31,15 @@ res_rtp_asterisk
    for a response that can never come until we give up on the response.
    Multiple subnets may be listed.
 
+Logging
+-------------------
+ * Added logger_queue_limit to the configuration options.
+   All log messages go to a queue serviced by a single thread
+   which does all the IO.  This setting controls how big that
+   queue can get (and therefore how much memory is allocated)
+   before new messages are discarded.
+   The default is 1000.
+
 res_pjsip_config_wizard
 ------------------
  * Two new parameters have been added to the pjsip config wizard.

configs/samples/logger.conf.sample

@@ -78,6 +78,14 @@
 ; Directory for log files is configures in asterisk.conf
 ; option astlogdir
 ;
+; All log messages go to a queue serviced by a single thread
+; which does all the IO.  This setting controls how big that
+; queue can get (and therefore how much memory is allocated)
+; before new messages are discarded.
+; The default is 1000
+;logger_queue_limit = 250
+;
+;
 [logfiles]
 ;
 ; Format is:

include/asterisk/logger.h

@@ -507,6 +507,22 @@ void ast_verb_console_set(int verb_level);
  */
 int ast_is_logger_initialized(void);
 
+/*!
+ * \brief Set the maximum number of messages allowed in the processing queue
+ *
+ * \param queue_limit
+ *
+ * \return Nothing
+ */
+void ast_logger_set_queue_limit(int queue_limit);
+
+/*!
+ * \brief Get the maximum number of messages allowed in the processing queue
+ *
+ * \return Queue limit
+ */
+int ast_logger_get_queue_limit(void);
+
 #if defined(__cplusplus) || defined(c_plusplus)
 }
 #endif

main/logger.c

@@ -86,6 +86,11 @@ static int display_callids;
 
 AST_THREADSTORAGE(unique_callid);
 
+static int logger_queue_size;
+static int logger_queue_limit = 1000;
+static int logger_messages_discarded;
+static unsigned int high_water_alert;
+
 static enum rotatestrategy {
 	NONE = 0,                /* Do not rotate log files at all, instead rely on external mechanisms */
 	SEQUENTIAL = 1 << 0,     /* Original method - create a new file, in order */
@@ -719,6 +724,16 @@ static int init_logger_chain(const char *altconf)
 			fprintf(stderr, "rotatetimestamp option has been deprecated.  Please use rotatestrategy instead.\n");
 		}
 	}
+	if ((s = ast_variable_retrieve(cfg, "general", "logger_queue_limit"))) {
+		if (sscanf(s, "%30d", &logger_queue_limit) != 1) {
+			fprintf(stderr, "logger_queue_limit has an invalid value.  Leaving at default of %d.\n",
+				logger_queue_limit);
+		}
+		if (logger_queue_limit < 10) {
+			fprintf(stderr, "logger_queue_limit must be >= 10. Setting to 10.\n");
+			logger_queue_limit = 10;
+		}
+	}
 
 	var = ast_variable_browse(cfg, "logfiles");
 	for (; var; var = var->next) {
@@ -1297,6 +1312,7 @@ static char *handle_logger_show_channels(struct ast_cli_entry *e, int cmd, struc
 	case CLI_GENERATE:
 		return NULL;
 	}
+	ast_cli(a->fd, "Logger queue limit: %d\n\n", logger_queue_limit);
 	ast_cli(a->fd, FORMATL, "Channel", "Type", "Formatter", "Status");
 	ast_cli(a->fd, "Configuration\n");
 	ast_cli(a->fd, FORMATL, "-------", "----", "---------", "------");
@@ -1585,6 +1601,79 @@ static void logger_print_normal(struct logmsg *logmsg)
 	return;
 }
 
+static struct logmsg * __attribute__((format(printf, 7, 0))) format_log_message_ap(int level,
+	int sublevel, const char *file, int line, const char *function, ast_callid callid,
+	const char *fmt, va_list ap)
+{
+	struct logmsg *logmsg = NULL;
+	struct ast_str *buf = NULL;
+	struct ast_tm tm;
+	struct timeval now = ast_tvnow();
+	int res = 0;
+	char datestring[256];
+
+	if (!(buf = ast_str_thread_get(&log_buf, LOG_BUF_INIT_SIZE))) {
+		return NULL;
+	}
+
+	/* Build string */
+	res = ast_str_set_va(&buf, BUFSIZ, fmt, ap);
+
+	/* If the build failed, then abort and free this structure */
+	if (res == AST_DYNSTR_BUILD_FAILED) {
+		return NULL;
+	}
+
+	/* Create a new logging message */
+	if (!(logmsg = ast_calloc_with_stringfields(1, struct logmsg, res + 128))) {
+		return NULL;
+	}
+
+	/* Copy string over */
+	ast_string_field_set(logmsg, message, ast_str_buffer(buf));
+
+	/* Set type */
+	if (level == __LOG_VERBOSE) {
+		logmsg->type = LOGMSG_VERBOSE;
+	} else {
+		logmsg->type = LOGMSG_NORMAL;
+	}
+
+	if (display_callids && callid) {
+		logmsg->callid = callid;
+	}
+
+	/* Create our date/time */
+	ast_localtime(&now, &tm, NULL);
+	ast_strftime(datestring, sizeof(datestring), dateformat, &tm);
+	ast_string_field_set(logmsg, date, datestring);
+
+	/* Copy over data */
+	logmsg->level = level;
+	logmsg->sublevel = sublevel;
+	logmsg->line = line;
+	ast_string_field_set(logmsg, level_name, levels[level]);
+	ast_string_field_set(logmsg, file, file);
+	ast_string_field_set(logmsg, function, function);
+	logmsg->lwp = ast_get_tid();
+
+	return logmsg;
+}
+
+static struct logmsg * __attribute__((format(printf, 7, 0))) format_log_message(int level,
+	int sublevel, const char *file, int line, const char *function, ast_callid callid,
+	const char *fmt, ...)
+{
+	struct logmsg *logmsg;
+	va_list ap;
+
+	va_start(ap, fmt);
+	logmsg = format_log_message_ap(level, sublevel, file, line, function, callid, fmt, ap);
+	va_end(ap);
+
+	return logmsg;
+}
+
 /*! \brief Actual logging thread */
 static void *logger_thread(void *data)
 {
@@ -1601,8 +1690,21 @@ static void *logger_thread(void *data)
 				ast_cond_wait(&logcond, &logmsgs.lock);
 			}
 		}
+
+		if (high_water_alert) {
+			msg = format_log_message(__LOG_WARNING, 0, "logger", 0, "***", 0,
+				"Logging resumed.  %d message%s discarded.\n",
+				logger_messages_discarded, logger_messages_discarded == 1 ? "" : "s");
+			if (msg) {
+				AST_LIST_INSERT_TAIL(&logmsgs, msg, list);
+			}
+			high_water_alert = 0;
+			logger_messages_discarded = 0;
+		}
+
 		next = AST_LIST_FIRST(&logmsgs);
 		AST_LIST_HEAD_INIT_NOLOCK(&logmsgs);
+		logger_queue_size = 0;
 		AST_LIST_UNLOCK(&logmsgs);
 
 		/* Otherwise go through and process each message in the order added */
@@ -1861,79 +1963,36 @@ void ast_callid_threadstorage_auto_clean(ast_callid callid, int callid_created)
 /*!
  * \brief send log messages to syslog and/or the console
  */
-static void __attribute__((format(printf, 7, 0))) ast_log_full(int level, int sublevel, const char *file, int line, const char *function, ast_callid callid, const char *fmt, va_list ap)
+static void __attribute__((format(printf, 7, 0))) ast_log_full(int level, int sublevel,
+	const char *file, int line, const char *function, ast_callid callid,
+	const char *fmt, va_list ap)
 {
 	struct logmsg *logmsg = NULL;
-	struct ast_str *buf = NULL;
-	struct ast_tm tm;
-	struct timeval now = ast_tvnow();
-	int res = 0;
-	char datestring[256];
 
 	if (level == __LOG_VERBOSE && ast_opt_remote && ast_opt_exec) {
 		return;
 	}
 
-	if (!(buf = ast_str_thread_get(&log_buf, LOG_BUF_INIT_SIZE)))
-		return;
-
-	if (level != __LOG_VERBOSE && AST_RWLIST_EMPTY(&logchannels)) {
-		/*
-		 * we don't have the logger chain configured yet,
-		 * so just log to stdout
-		 */
-		int result;
-		result = ast_str_set_va(&buf, BUFSIZ, fmt, ap); /* XXX BUFSIZ ? */
-		if (result != AST_DYNSTR_BUILD_FAILED) {
-			term_filter_escapes(ast_str_buffer(buf));
-			fputs(ast_str_buffer(buf), stdout);
+	AST_LIST_LOCK(&logmsgs);
+	if (logger_queue_size >= logger_queue_limit && !close_logger_thread) {
+		logger_messages_discarded++;
+		if (!high_water_alert && !close_logger_thread) {
+			logmsg = format_log_message(__LOG_WARNING, 0, "logger", 0, "***", 0,
+				"Log queue threshold (%d) exceeded.  Discarding new messages.\n", logger_queue_limit);
+			AST_LIST_INSERT_TAIL(&logmsgs, logmsg, list);
+			high_water_alert = 1;
+			ast_cond_signal(&logcond);
 		}
+		AST_LIST_UNLOCK(&logmsgs);
 		return;
 	}
+	AST_LIST_UNLOCK(&logmsgs);
 
-	/* Ignore anything that never gets logged anywhere */
-	if (level != __LOG_VERBOSE && !(global_logmask & (1 << level)))
-		return;
-
-	/* Build string */
-	res = ast_str_set_va(&buf, BUFSIZ, fmt, ap);
-
-	/* If the build failed, then abort and free this structure */
-	if (res == AST_DYNSTR_BUILD_FAILED)
+	logmsg = format_log_message_ap(level, sublevel, file, line, function, callid, fmt, ap);
+	if (!logmsg) {
 		return;
-
-	/* Create a new logging message */
-	if (!(logmsg = ast_calloc_with_stringfields(1, struct logmsg, res + 128)))
-		return;
-
-	/* Copy string over */
-	ast_string_field_set(logmsg, message, ast_str_buffer(buf));
-
-	/* Set type */
-	if (level == __LOG_VERBOSE) {
-		logmsg->type = LOGMSG_VERBOSE;
-	} else {
-		logmsg->type = LOGMSG_NORMAL;
 	}
 
-	if (display_callids && callid) {
-		logmsg->callid = callid;
-	}
-
-	/* Create our date/time */
-	ast_localtime(&now, &tm, NULL);
-	ast_strftime(datestring, sizeof(datestring), dateformat, &tm);
-	ast_string_field_set(logmsg, date, datestring);
-
-	/* Copy over data */
-	logmsg->level = level;
-	logmsg->sublevel = sublevel;
-	logmsg->line = line;
-	ast_string_field_set(logmsg, level_name, levels[level]);
-	ast_string_field_set(logmsg, file, file);
-	ast_string_field_set(logmsg, function, function);
-	logmsg->lwp = ast_get_tid();
-
 	/* If the logger thread is active, append it to the tail end of the list - otherwise skip that step */
 	if (logthread != AST_PTHREADT_NULL) {
 		AST_LIST_LOCK(&logmsgs);
@@ -1942,6 +2001,7 @@ static void __attribute__((format(printf, 7, 0))) ast_log_full(int level, int su
 			logmsg_free(logmsg);
 		} else {
 			AST_LIST_INSERT_TAIL(&logmsgs, logmsg, list);
+			logger_queue_size++;
 			ast_cond_signal(&logcond);
 		}
 		AST_LIST_UNLOCK(&logmsgs);
@@ -2300,3 +2360,12 @@ const char *ast_logger_get_dateformat(void)
 	return dateformat;
 }
 
+void ast_logger_set_queue_limit(int queue_limit)
+{
+	logger_queue_limit = queue_limit;
+}
+
+int ast_logger_get_queue_limit(void)
+{
+	return logger_queue_limit;
+}

tests/test_logger.c

@@ -188,9 +188,76 @@ static char *handle_cli_performance_test(struct ast_cli_entry *e, int cmd, struc
 	return CLI_SUCCESS;
 }
 
+static char *handle_cli_queue_test(struct ast_cli_entry *e, int cmd, struct ast_cli_args *a)
+{
+	unsigned int level;
+	int current_queue_limit;
+	unsigned int x;
+	struct timeval start, end;
+	int elapsed;
+	char tmppath[] = "/tmp/asterisk_logger_queue.XXXXXX";
+	int fd;
+
+	switch (cmd) {
+	case CLI_INIT:
+		e->command = "logger test queue";
+		e->usage = ""
+			"Usage: logger test queue\n"
+			"";
+		return NULL;
+	case CLI_GENERATE:
+		return NULL;
+	}
+
+	fd = mkstemp(tmppath);
+	if (fd < 0) {
+		ast_cli(a->fd, "Test: Failed, could not create temporary log file '%s'.\n", tmppath);
+		return CLI_SUCCESS;
+	}
+
+	level = ast_logger_register_level("queuetest");
+	if (level < 0) {
+		ast_cli(a->fd, "Test: Failed, could not register level 'queuetest'.\n");
+		return CLI_SUCCESS;
+	}
+	ast_cli(a->fd, "Test: got level %u for 'queuetest'.\n", level);
+
+	if (ast_logger_create_channel(tmppath, "queuetest") != AST_LOGGER_SUCCESS) {
+		ast_cli(a->fd, "Test: Unable to create logger channel '%s'\n", tmppath);
+		goto error;
+	}
+
+	current_queue_limit = ast_logger_get_queue_limit();
+	ast_cli(a->fd, "Test: Current queue limit: %d.  Setting to 100 for test.\n", current_queue_limit);
+	ast_logger_set_queue_limit(100);
+
+	ast_cli(a->fd, "Test: You should see SOME 'exceeded' and 'resumed' messages after the test "
+		"is completed.  How many is dependent on system resources.\n");
+
+	start = ast_tvnow();
+	for (x = 0; x < 10000; x++) {
+		ast_log_dynamic_level(level, "Performance test log message %2d\n", x);
+	}
+	end = ast_tvnow();
+	elapsed = ast_tvdiff_ms(end, start);
+	ast_cli(a->fd, "Test: 10,000 messages in %f seconds.\n", (float) elapsed / 1000);
+	ast_cli(a->fd, "Test: Completed.  Resetting queue limit to %d.\n", current_queue_limit);
+	ast_logger_set_queue_limit(current_queue_limit);
+
+error:
+
+	ast_logger_remove_channel(tmppath);
+	ast_logger_unregister_level("queuetest");
+	close(fd);
+	unlink(tmppath);
+
+	return CLI_SUCCESS;
+}
+
 static struct ast_cli_entry cli_logger[] = {
 	AST_CLI_DEFINE(handle_cli_dynamic_level_test, "Test the dynamic logger level implementation"),
 	AST_CLI_DEFINE(handle_cli_performance_test, "Test the logger performance"),
+	AST_CLI_DEFINE(handle_cli_queue_test, "Test the logger queue"),
 };
 
 static int unload_module(void)