shared: move psi-util.[ch] to basic/ so that we can use it in sd-event

src/basic/meson.build

@@ -65,6 +65,7 @@ basic_sources = files(
         'proc-cmdline.c',
         'process-util.c',
         'procfs-util.c',
+        'psi-util.c',
         'random-util.c',
         'ratelimit.c',
         'recurse-dir.c',

src/basic/psi-util.c

@@ -0,0 +1,123 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include <stdio.h>
+#include <unistd.h>
+
+#include "alloc-util.h"
+#include "errno-util.h"
+#include "extract-word.h"
+#include "fd-util.h"
+#include "fileio.h"
+#include "parse-util.h"
+#include "psi-util.h"
+#include "string-util.h"
+#include "stat-util.h"
+#include "strv.h"
+
+int read_resource_pressure(const char *path, PressureType type, ResourcePressure *ret) {
+        _cleanup_free_ char *line = NULL;
+        _cleanup_fclose_ FILE *f = NULL;
+        unsigned field_filled = 0;
+        ResourcePressure rp = {};
+        const char *t, *cline;
+        char *word;
+        int r;
+
+        assert(path);
+        assert(IN_SET(type, PRESSURE_TYPE_SOME, PRESSURE_TYPE_FULL));
+        assert(ret);
+
+        if (type == PRESSURE_TYPE_SOME)
+                t = "some";
+        else if (type == PRESSURE_TYPE_FULL)
+                t = "full";
+        else
+                return -EINVAL;
+
+        r = fopen_unlocked(path, "re", &f);
+        if (r < 0)
+                return r;
+
+        for (;;) {
+                _cleanup_free_ char *l = NULL;
+                char *w;
+
+                r = read_line(f, LONG_LINE_MAX, &l);
+                if (r < 0)
+                        return r;
+                if (r == 0)
+                        break;
+
+                w = first_word(l, t);
+                if (w) {
+                        line = TAKE_PTR(l);
+                        cline = w;
+                        break;
+                }
+        }
+
+        if (!line)
+                return -ENODATA;
+
+        /* extracts either avgX=Y.Z or total=X */
+        while ((r = extract_first_word(&cline, &word, NULL, 0)) > 0) {
+                _cleanup_free_ char *w = word;
+                const char *v;
+
+                if ((v = startswith(w, "avg10="))) {
+                        if (field_filled & (1U << 0))
+                                return -EINVAL;
+
+                        field_filled |= 1U << 0;
+                        r = parse_loadavg_fixed_point(v, &rp.avg10);
+                } else if ((v = startswith(w, "avg60="))) {
+                        if (field_filled & (1U << 1))
+                                return -EINVAL;
+
+                        field_filled |= 1U << 1;
+                        r = parse_loadavg_fixed_point(v, &rp.avg60);
+                } else if ((v = startswith(w, "avg300="))) {
+                        if (field_filled & (1U << 2))
+                                return -EINVAL;
+
+                        field_filled |= 1U << 2;
+                        r = parse_loadavg_fixed_point(v, &rp.avg300);
+                } else if ((v = startswith(w, "total="))) {
+                        if (field_filled & (1U << 3))
+                                return -EINVAL;
+
+                        field_filled |= 1U << 3;
+                        r = safe_atou64(v, &rp.total);
+                } else
+                        continue;
+
+                if (r < 0)
+                        return r;
+        }
+
+        if (r < 0)
+                return r;
+
+        if (field_filled != 15U)
+                return -EINVAL;
+
+        *ret = rp;
+        return 0;
+}
+
+int is_pressure_supported(void) {
+        /* The pressure files, both under /proc and in cgroups, will exist
+         * even if the kernel has PSI support disabled; we have to read
+         * the file to make sure it doesn't return -EOPNOTSUPP */
+        FOREACH_STRING(p, "/proc/pressure/cpu", "/proc/pressure/io", "/proc/pressure/memory") {
+                int r;
+
+                r = read_virtual_file(p, 0, NULL, NULL);
+                if (r == -ENOENT || ERRNO_IS_NOT_SUPPORTED(r))
+                        return 0;
+                if (r < 0)
+                        return r;
+        }
+
+        return 1;
+}

src/basic/psi-util.h

@@ -0,0 +1,30 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+#pragma once
+
+#include <stdbool.h>
+
+#include "parse-util.h"
+#include "time-util.h"
+
+typedef enum PressureType {
+        PRESSURE_TYPE_SOME,
+        PRESSURE_TYPE_FULL,
+} PressureType;
+
+/* Averages are stored in fixed-point with 11 bit fractions */
+typedef struct ResourcePressure {
+        loadavg_t avg10;
+        loadavg_t avg60;
+        loadavg_t avg300;
+        usec_t total;
+} ResourcePressure;
+
+/** Upstream 4.20+ format
+ *
+ *  some avg10=0.22 avg60=0.17 avg300=1.11 total=58761459
+ *  full avg10=0.23 avg60=0.16 avg300=1.08 total=58464525
+ */
+int read_resource_pressure(const char *path, PressureType type, ResourcePressure *ret);
+
+/* Was the kernel compiled with CONFIG_PSI=y? 1 if yes, 0 if not, negative on error. */
+int is_pressure_supported(void);