322 lines
8.5 KiB
C++
322 lines
8.5 KiB
C++
// SPDX-License-Identifier: BSD-2-Clause
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// author: Max Kellermann <max.kellermann@gmail.com>
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#include "Util.hxx"
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#include "system/Error.hxx"
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#ifdef __linux__
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#include <sched.h>
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#include <sys/syscall.h>
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#include <unistd.h>
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#include <dbus/dbus.h>
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#include <string.h>
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#include <sys/types.h>
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#include <errno.h>
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#include "lib/fmt/RuntimeError.hxx"
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#elif defined(_WIN32)
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#include <windows.h>
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#endif
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#ifdef __linux__
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const char* RTKIT_SERVICE_NAME = "org.freedesktop.RealtimeKit1";
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const char* RTKIT_OBJECT_PATH = "/org/freedesktop/RealtimeKit1";
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// static int
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// rtkit_get_max_realtime_priority(DBusConnection &connection)
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// {
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// // TODO: Implement this function
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// DBusError error;
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// }
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// static void
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// rtkit_make_realtime(DBusConnection &connection, pid_t thread, int priority)
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// {
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// // TODO: Implement this function
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// }
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#endif
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// TODO: minimize and drop
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#ifdef __linux__
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#define RTKIT_SERVICE_NAME "org.freedesktop.RealtimeKit1"
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#define RTKIT_OBJECT_PATH "/org/freedesktop/RealtimeKit1"
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static pid_t _gettid(void) {
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return (pid_t) syscall(SYS_gettid);
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}
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static int translate_error(const char *name) {
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if (strcmp(name, DBUS_ERROR_NO_MEMORY) == 0)
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return -ENOMEM;
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if (strcmp(name, DBUS_ERROR_SERVICE_UNKNOWN) == 0 ||
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strcmp(name, DBUS_ERROR_NAME_HAS_NO_OWNER) == 0)
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return -ENOENT;
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if (strcmp(name, DBUS_ERROR_ACCESS_DENIED) == 0 ||
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strcmp(name, DBUS_ERROR_AUTH_FAILED) == 0)
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return -EACCES;
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return -EIO;
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}
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static long long rtkit_get_int_property(DBusConnection *connection, const char* propname, long long* propval) {
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DBusMessage *m = NULL, *r = NULL;
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DBusMessageIter iter, subiter;
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dbus_int64_t i64;
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dbus_int32_t i32;
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DBusError error;
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int current_type;
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long long ret;
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const char * interfacestr = "org.freedesktop.RealtimeKit1";
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dbus_error_init(&error);
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if (!(m = dbus_message_new_method_call(
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RTKIT_SERVICE_NAME,
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RTKIT_OBJECT_PATH,
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"org.freedesktop.DBus.Properties",
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"Get"))) {
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ret = -ENOMEM;
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goto finish;
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}
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if (!dbus_message_append_args(
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m,
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DBUS_TYPE_STRING, &interfacestr,
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DBUS_TYPE_STRING, &propname,
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DBUS_TYPE_INVALID)) {
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ret = -ENOMEM;
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goto finish;
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}
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if (!(r = dbus_connection_send_with_reply_and_block(connection, m, -1, &error))) {
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ret = translate_error(error.name);
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goto finish;
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}
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if (dbus_set_error_from_message(&error, r)) {
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ret = translate_error(error.name);
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goto finish;
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}
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ret = -EBADMSG;
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dbus_message_iter_init(r, &iter);
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while ((current_type = dbus_message_iter_get_arg_type (&iter)) != DBUS_TYPE_INVALID) {
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if (current_type == DBUS_TYPE_VARIANT) {
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dbus_message_iter_recurse(&iter, &subiter);
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while ((current_type = dbus_message_iter_get_arg_type (&subiter)) != DBUS_TYPE_INVALID) {
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if (current_type == DBUS_TYPE_INT32) {
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dbus_message_iter_get_basic(&subiter, &i32);
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*propval = i32;
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ret = 0;
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}
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if (current_type == DBUS_TYPE_INT64) {
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dbus_message_iter_get_basic(&subiter, &i64);
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*propval = i64;
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ret = 0;
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}
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dbus_message_iter_next (&subiter);
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}
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}
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dbus_message_iter_next (&iter);
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}
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finish:
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if (m)
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dbus_message_unref(m);
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if (r)
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dbus_message_unref(r);
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dbus_error_free(&error);
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return ret;
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}
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static int rtkit_get_max_realtime_priority(DBusConnection *connection) {
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long long retval;
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int err;
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err = rtkit_get_int_property(connection, "MaxRealtimePriority", &retval);
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return err < 0 ? err : retval;
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}
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static int rtkit_make_realtime(DBusConnection *connection, pid_t thread, int priority) {
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DBusMessage *m = NULL, *r = NULL;
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dbus_uint64_t u64;
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dbus_uint32_t u32;
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DBusError error;
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int ret;
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dbus_error_init(&error);
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if (thread == 0)
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thread = _gettid();
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if (!(m = dbus_message_new_method_call(
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RTKIT_SERVICE_NAME,
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RTKIT_OBJECT_PATH,
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"org.freedesktop.RealtimeKit1",
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"MakeThreadRealtime"))) {
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ret = -ENOMEM;
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goto finish;
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}
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u64 = (dbus_uint64_t) thread;
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u32 = (dbus_uint32_t) priority;
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if (!dbus_message_append_args(
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m,
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DBUS_TYPE_UINT64, &u64,
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DBUS_TYPE_UINT32, &u32,
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DBUS_TYPE_INVALID)) {
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ret = -ENOMEM;
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goto finish;
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}
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if (!(r = dbus_connection_send_with_reply_and_block(connection, m, -1, &error))) {
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ret = translate_error(error.name);
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goto finish;
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}
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if (dbus_set_error_from_message(&error, r)) {
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ret = translate_error(error.name);
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goto finish;
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}
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ret = 0;
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finish:
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if (m)
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dbus_message_unref(m);
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if (r)
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dbus_message_unref(r);
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dbus_error_free(&error);
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return ret;
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}
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#endif
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#ifdef __linux__
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#ifndef ANDROID
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static int
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linux_ioprio_set(int which, int who, int ioprio) noexcept
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{
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return syscall(__NR_ioprio_set, which, who, ioprio);
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}
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static void
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ioprio_set_idle() noexcept
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{
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static constexpr int _IOPRIO_WHO_PROCESS = 1;
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static constexpr int _IOPRIO_CLASS_IDLE = 3;
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static constexpr int _IOPRIO_CLASS_SHIFT = 13;
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static constexpr int _IOPRIO_IDLE =
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(_IOPRIO_CLASS_IDLE << _IOPRIO_CLASS_SHIFT) | 7;
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linux_ioprio_set(_IOPRIO_WHO_PROCESS, 0, _IOPRIO_IDLE);
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}
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#endif /* !ANDROID */
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/**
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* Wrapper for the "sched_setscheduler" system call. We don't use the
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* one from the C library because Musl has an intentionally broken
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* implementation.
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*/
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static int
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linux_sched_setscheduler(pid_t pid, int sched,
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const struct sched_param *param) noexcept
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{
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return syscall(__NR_sched_setscheduler, pid, sched, param);
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}
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#endif
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void
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SetThreadIdlePriority() noexcept
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{
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#ifdef __linux__
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#ifdef SCHED_IDLE
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static struct sched_param sched_param;
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linux_sched_setscheduler(0, SCHED_IDLE, &sched_param);
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#endif
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#ifndef ANDROID
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/* this system call is forbidden via seccomp on Android 8 and
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leads to crash (SIGSYS) */
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ioprio_set_idle();
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#endif
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#elif defined(_WIN32)
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SetThreadPriority(GetCurrentThread(), THREAD_PRIORITY_IDLE);
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#endif
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}
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void
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SetThreadRealtime()
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{
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#ifdef __linux__
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struct sched_param sched_param;
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sched_param.sched_priority = 20;
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int policy = SCHED_FIFO;
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#ifdef SCHED_RESET_ON_FORK
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policy |= SCHED_RESET_ON_FORK;
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#endif
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int res = linux_sched_setscheduler(0, policy, &sched_param);
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if (res < 0 && errno == EPERM) {
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DBusError error;
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DBusConnection *system_bus;
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dbus_error_init(&error);
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system_bus = dbus_bus_get(DBUS_BUS_SYSTEM, &error);
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if (dbus_error_is_set(&error)) {
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throw FmtRuntimeError("could not connect to dbus: %s", error.message);
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}
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dbus_error_free(&error);
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int max_realtime_priority;
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if ((max_realtime_priority = rtkit_get_max_realtime_priority(system_bus)) < 0) {
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dbus_connection_unref(system_bus);
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throw MakeErrno("could not retrieve maximum realtime priority allowed");
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}
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if (max_realtime_priority < sched_param.sched_priority) {
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sched_param.sched_priority = max_realtime_priority;
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/* dbus_connection_unref(system_bus); */
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/* throw MakeErrno("maximum realtime priority is below 40"); */
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}
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if (rtkit_make_realtime(system_bus, 0, sched_param.sched_priority) < 0) {
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dbus_connection_unref(system_bus);
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throw MakeErrno("failed to request realtime scheduling");
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}
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dbus_connection_unref(system_bus);
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res = 0;
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}
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// if (res < 0) {
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// throw MakeErrno("sched_setscheduler failed");
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// }
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#endif // __linux__
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}
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