unix,win: add uv_os_{get,set}priority()

Refs: https://github.com/nodejs/node/pull/21675
PR-URL: https://github.com/libuv/libuv/pull/1945
Reviewed-By: Santiago Gimeno <santiago.gimeno@gmail.com>
Reviewed-By: Richard Lau <riclau@uk.ibm.com>

CMakeLists.txt

@@ -98,6 +98,7 @@ set(uv_test_sources
     test/test-poll-closesocket.c
     test/test-poll-oob.c
     test/test-poll.c
+    test/test-process-priority.c
     test/test-process-title-threadsafe.c
     test/test-process-title.c
     test/test-queue-foreach-delete.c

Makefile.am

@@ -224,6 +224,7 @@ test_run_tests_SOURCES = test/blackhole-server.c \
                          test/test-poll-close-doesnt-corrupt-stack.c \
                          test/test-poll-closesocket.c \
                          test/test-poll-oob.c \
+                         test/test-process-priority.c \
                          test/test-process-title.c \
                          test/test-process-title-threadsafe.c \
                          test/test-queue-foreach-delete.c \

docs/src/misc.rst

@@ -517,3 +517,31 @@ API
     storage required to hold the value.
 
     .. versionadded:: 1.12.0
+
+.. c:function:: int uv_os_getpriority(uv_pid_t pid, int* priority)
+
+    Retrieves the scheduling priority of the process specified by `pid`. The
+    returned value of `priority` is between -20 (high priority) and 19 (low
+    priority).
+
+    .. note::
+        On Windows, the returned priority will equal one of the `UV_PRIORITY`
+        constants.
+
+    .. versionadded:: 1.23.0
+
+.. c:function:: int uv_os_setpriority(uv_pid_t pid, int priority)
+
+    Sets the scheduling priority of the process specified by `pid`. The
+    `priority` value range is between -20 (high priority) and 19 (low priority).
+    The constants `UV_PRIORITY_LOW`, `UV_PRIORITY_BELOW_NORMAL`,
+    `UV_PRIORITY_NORMAL`, `UV_PRIORITY_ABOVE_NORMAL`, `UV_PRIORITY_HIGH`, and
+    `UV_PRIORITY_HIGHEST` are also provided for convenience.
+
+    .. note::
+        On Windows, this function utilizes `SetPriorityClass()`. The `priority`
+        argument is mapped to a Windows priority class. When retrieving the
+        process priority, the result will equal one of the `UV_PRIORITY`
+        constants, and not necessarily the exact value of `priority`.
+
+    .. versionadded:: 1.23.0

include/uv.h

@@ -1100,6 +1100,16 @@ UV_EXTERN void uv_os_free_passwd(uv_passwd_t* pwd);
 UV_EXTERN uv_pid_t uv_os_getpid(void);
 UV_EXTERN uv_pid_t uv_os_getppid(void);
 
+#define UV_PRIORITY_LOW 19
+#define UV_PRIORITY_BELOW_NORMAL 10
+#define UV_PRIORITY_NORMAL 0
+#define UV_PRIORITY_ABOVE_NORMAL -7
+#define UV_PRIORITY_HIGH -14
+#define UV_PRIORITY_HIGHEST -20
+
+UV_EXTERN int uv_os_getpriority(uv_pid_t pid, int* priority);
+UV_EXTERN int uv_os_setpriority(uv_pid_t pid, int priority);
+
 UV_EXTERN int uv_cpu_info(uv_cpu_info_t** cpu_infos, int* count);
 UV_EXTERN void uv_free_cpu_info(uv_cpu_info_t* cpu_infos, int count);
 

src/unix/core.c

@@ -1350,3 +1350,31 @@ uv_pid_t uv_os_getpid(void) {
 uv_pid_t uv_os_getppid(void) {
   return getppid();
 }
+
+
+int uv_os_getpriority(uv_pid_t pid, int* priority) {
+  int r;
+
+  if (priority == NULL)
+    return UV_EINVAL;
+
+  errno = 0;
+  r = getpriority(PRIO_PROCESS, (int) pid);
+
+  if (r == -1 && errno != 0)
+    return UV__ERR(errno);
+
+  *priority = r;
+  return 0;
+}
+
+
+int uv_os_setpriority(uv_pid_t pid, int priority) {
+  if (priority < UV_PRIORITY_HIGHEST || priority > UV_PRIORITY_LOW)
+    return UV_EINVAL;
+
+  if (setpriority(PRIO_PROCESS, (int) pid, priority) != 0)
+    return UV__ERR(errno);
+
+  return 0;
+}

src/win/util.c

@@ -1530,3 +1530,97 @@ int uv_os_gethostname(char* buffer, size_t* size) {
   *size = len;
   return 0;
 }
+
+
+static int uv__get_handle(uv_pid_t pid, int access, HANDLE* handle) {
+  int r;
+
+  if (pid == 0)
+    *handle = GetCurrentProcess();
+  else
+    *handle = OpenProcess(access, FALSE, pid);
+
+  if (*handle == NULL) {
+    r = GetLastError();
+
+    if (r == ERROR_INVALID_PARAMETER)
+      return UV_ESRCH;
+    else
+      return uv_translate_sys_error(r);
+  }
+
+  return 0;
+}
+
+
+int uv_os_getpriority(uv_pid_t pid, int* priority) {
+  HANDLE handle;
+  int r;
+
+  if (priority == NULL)
+    return UV_EINVAL;
+
+  r = uv__get_handle(pid, PROCESS_QUERY_LIMITED_INFORMATION, &handle);
+
+  if (r != 0)
+    return r;
+
+  r = GetPriorityClass(handle);
+
+  if (r == 0) {
+    r = uv_translate_sys_error(GetLastError());
+  } else {
+    /* Map Windows priority classes to Unix nice values. */
+    if (r == REALTIME_PRIORITY_CLASS)
+      *priority = UV_PRIORITY_HIGHEST;
+    else if (r == HIGH_PRIORITY_CLASS)
+      *priority = UV_PRIORITY_HIGH;
+    else if (r == ABOVE_NORMAL_PRIORITY_CLASS)
+      *priority = UV_PRIORITY_ABOVE_NORMAL;
+    else if (r == NORMAL_PRIORITY_CLASS)
+      *priority = UV_PRIORITY_NORMAL;
+    else if (r == BELOW_NORMAL_PRIORITY_CLASS)
+      *priority = UV_PRIORITY_BELOW_NORMAL;
+    else  /* IDLE_PRIORITY_CLASS */
+      *priority = UV_PRIORITY_LOW;
+
+    r = 0;
+  }
+
+  CloseHandle(handle);
+  return r;
+}
+
+
+int uv_os_setpriority(uv_pid_t pid, int priority) {
+  HANDLE handle;
+  int priority_class;
+  int r;
+
+  /* Map Unix nice values to Windows priority classes. */
+  if (priority < UV_PRIORITY_HIGHEST || priority > UV_PRIORITY_LOW)
+    return UV_EINVAL;
+  else if (priority < UV_PRIORITY_HIGH)
+    priority_class = REALTIME_PRIORITY_CLASS;
+  else if (priority < UV_PRIORITY_ABOVE_NORMAL)
+    priority_class = HIGH_PRIORITY_CLASS;
+  else if (priority < UV_PRIORITY_NORMAL)
+    priority_class = ABOVE_NORMAL_PRIORITY_CLASS;
+  else if (priority < UV_PRIORITY_BELOW_NORMAL)
+    priority_class = NORMAL_PRIORITY_CLASS;
+  else if (priority < UV_PRIORITY_LOW)
+    priority_class = BELOW_NORMAL_PRIORITY_CLASS;
+  else
+    priority_class = IDLE_PRIORITY_CLASS;
+
+  r = uv__get_handle(pid, PROCESS_SET_INFORMATION, &handle);
+
+  if (r != 0)
+    return r;
+
+  if (SetPriorityClass(handle, priority_class) == 0)
+    r = uv_translate_sys_error(GetLastError());
+
+  CloseHandle(handle);
+  return r;
+}

test/test-list.h

@@ -214,6 +214,7 @@ TEST_DECLARE   (pipe_close_stdout_read_stdin)
 TEST_DECLARE   (pipe_set_non_blocking)
 TEST_DECLARE   (pipe_set_chmod)
 TEST_DECLARE   (process_ref)
+TEST_DECLARE   (process_priority)
 TEST_DECLARE   (has_ref)
 TEST_DECLARE   (active)
 TEST_DECLARE   (embed)
@@ -689,6 +690,7 @@ TASK_LIST_START
   TEST_ENTRY  (pipe_ref4)
   TEST_HELPER (pipe_ref4, pipe_echo_server)
   TEST_ENTRY  (process_ref)
+  TEST_ENTRY  (process_priority)
   TEST_ENTRY  (has_ref)
 
   TEST_ENTRY  (loop_handles)

test/test-process-priority.c

@@ -0,0 +1,81 @@
+/* Copyright libuv contributors. All rights reserved.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to
+ * deal in the Software without restriction, including without limitation the
+ * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+#include "uv.h"
+#include "task.h"
+
+
+TEST_IMPL(process_priority) {
+  int priority;
+  int r;
+  int i;
+
+#if defined(__MVS__)
+  if (uv_os_setpriority(0, 0) == UV_ENOSYS)
+    RETURN_SKIP("functionality not supported on zOS");
+#endif
+
+  /* Verify that passing a NULL pointer returns UV_EINVAL. */
+  r = uv_os_getpriority(0, NULL);
+  ASSERT(r == UV_EINVAL);
+
+  /* Verify that all valid values work. */
+  for (i = UV_PRIORITY_HIGHEST; i <= UV_PRIORITY_LOW; i++) {
+    r = uv_os_setpriority(0, i);
+
+    /* If UV_EACCES is returned, the current user doesn't have permission to
+       set this specific priority. */
+    if (r == UV_EACCES)
+      continue;
+
+    ASSERT(r == 0);
+    ASSERT(uv_os_getpriority(0, &priority) == 0);
+
+    /* Verify that the priority values match on Unix, and are range mapped
+       on Windows. */
+#ifndef _WIN32
+    ASSERT(priority == i);
+#else
+    if (i < UV_PRIORITY_HIGH)
+      ASSERT(priority == UV_PRIORITY_HIGHEST);
+    else if (i < UV_PRIORITY_ABOVE_NORMAL)
+      ASSERT(priority == UV_PRIORITY_HIGH);
+    else if (i < UV_PRIORITY_NORMAL)
+      ASSERT(priority == UV_PRIORITY_ABOVE_NORMAL);
+    else if (i < UV_PRIORITY_BELOW_NORMAL)
+      ASSERT(priority == UV_PRIORITY_NORMAL);
+    else if (i < UV_PRIORITY_LOW)
+      ASSERT(priority == UV_PRIORITY_BELOW_NORMAL);
+    else
+      ASSERT(priority == UV_PRIORITY_LOW);
+#endif
+
+    /* Verify that the current PID and 0 are equivalent. */
+    ASSERT(uv_os_getpriority(uv_os_getpid(), &r) == 0);
+    ASSERT(priority == r);
+  }
+
+  /* Verify that invalid priorities return UV_EINVAL. */
+  ASSERT(uv_os_setpriority(0, UV_PRIORITY_HIGHEST - 1) == UV_EINVAL);
+  ASSERT(uv_os_setpriority(0, UV_PRIORITY_LOW + 1) == UV_EINVAL);
+
+  return 0;
+}

test/test.gyp

@@ -80,6 +80,7 @@
         'test-poll-close-doesnt-corrupt-stack.c',
         'test-poll-closesocket.c',
         'test-poll-oob.c',
+        'test-process-priority.c',
         'test-process-title.c',
         'test-process-title-threadsafe.c',
         'test-queue-foreach-delete.c',