Replace pthread-based logging buffer with signal masking for thread safety

This commit replaces the pthread mutex-based synchronization in the
async logging buffer with signal masking, eliminating the pthread
dependency while maintaining thread safety.

Fixes: #38

Signed-off-by: Jindrich Novy <jnovy@redhat.com>

Author: jnovy

Makefile

@@ -5,7 +5,7 @@ LIBEXECDIR ?= ${PREFIX}/libexec
 PKG_CONFIG ?= pkg-config
 HEADERS := $(wildcard src/*.h)
 
-OBJS := src/conmon.o src/cmsg.o src/ctr_logging.o src/utils.o src/cli.o src/globals.o src/cgroup.o src/conn_sock.o src/oom.o src/ctrl.o src/ctr_stdio.o src/parent_pipe_fd.o src/ctr_exit.o src/runtime_args.o src/close_fds.o src/seccomp_notify.o
+OBJS := src/conmon.o src/cmsg.o src/ctr_logging.o src/ctr_logging_buffer.o src/utils.o src/cli.o src/globals.o src/cgroup.o src/conn_sock.o src/oom.o src/ctrl.o src/ctr_stdio.o src/parent_pipe_fd.o src/ctr_exit.o src/runtime_args.o src/close_fds.o src/seccomp_notify.o
 
 MAKEFILE_PATH := $(dir $(abspath $(lastword $(MAKEFILE_LIST))))
 

nix/derivation.nix

@@ -24,7 +24,7 @@ with pkgs; stdenv.mkDerivation rec {
     # Static builds will use PKG_CONFIG_PATH approach instead
   ];
   prePatch = ''
-    export CFLAGS='-static -pthread'
+    export CFLAGS='-static'
     export LDFLAGS='-s -w -static-libgcc -static'
     export EXTRA_LDFLAGS='-s -w -linkmode external -extldflags "-static -lm"'
     ${lib.optionalString (!enableSystemd) "export DISABLE_SYSTEMD=1"}

src/cli.c

@@ -1,6 +1,7 @@
 #include "cli.h"
 #include "globals.h"
 #include "ctr_logging.h"
+#include "ctr_logging_buffer.h"
 #include "config.h"
 #include "utils.h"
 
@@ -224,6 +225,14 @@ void process_cli()
 
 	configure_log_drivers(opt_log_path, opt_log_size_max, opt_log_global_size_max, opt_cid, opt_name, opt_log_tag, opt_log_labels);
 
+	/* Initialize async logging for improved log performance */
+	if (!init_async_logging()) {
+		nwarn("Failed to initialize async logging, falling back to direct logging");
+	} else {
+		/* Register cleanup handler for async logging */
+		atexit(shutdown_async_logging);
+	}
+
 	/* Warn if --no-container-partial-message is used without journald logging */
 	if (opt_no_container_partial_message && !logging_is_journald_enabled()) {
 		nwarnf("--no-container-partial-message has no effect without journald log driver");

src/conmon.c

@@ -14,6 +14,7 @@
 #include "conn_sock.h"
 #include "ctrl.h"
 #include "ctr_stdio.h"
+#include "ctr_logging_buffer.h"
 #include "config.h"
 #include "parent_pipe_fd.h"
 #include "ctr_exit.h"
@@ -418,6 +419,8 @@ int main(int argc, char *argv[])
 	if (mainfd_stderr >= 0) {
 		g_unix_fd_add(mainfd_stderr, G_IO_IN, stdio_cb, GINT_TO_POINTER(STDERR_PIPE));
 	}
+	/* Setup log buffer timer for async flushing */
+	setup_log_timer_in_main_loop();
 
 	if (opt_timeout > 0) {
 		g_timeout_add_seconds(opt_timeout, timeout_cb, NULL);

src/ctr_logging.c

@@ -1,5 +1,6 @@
 #define _GNU_SOURCE
 #include "ctr_logging.h"
+#include "ctr_logging_buffer.h"
 #include "cli.h"
 #include "config.h"
 #include <ctype.h>
@@ -761,6 +762,9 @@ static void set_k8s_timestamp(char *buf, ssize_t buflen, const char *pipename)
 /* Force closing any open FD. */
 void close_logging_fds(void)
 {
+	/* Shutdown async logging system */
+	shutdown_async_logging();
+
 	if (k8s_log_fd >= 0)
 		close(k8s_log_fd);
 	k8s_log_fd = -1;
@@ -1243,6 +1247,9 @@ static void reopen_k8s_file(void)
 
 void sync_logs(void)
 {
+	/* Flush any buffered logs before syncing */
+	flush_log_buffer();
+
 	/* Sync the logs to disk */
 	if (k8s_log_fd > 0)
 		if (fsync(k8s_log_fd) < 0)