1 files changed, 57 insertions(+), 21 deletions(-)

M main.cpp

@@ 70,6 70,18 @@ struct process_lookup_error: public std::runtime_error {
     using std::runtime_error::runtime_error;
 };
 
+constexpr auto tspec_diff(const timespec& t0, const timespec& t1) {
+    timespec t {
+        .tv_sec = t1.tv_sec - t0.tv_sec,
+        .tv_nsec = t1.tv_nsec - t0.tv_nsec
+    };
+    if (t.tv_nsec < 0) {
+        --t.tv_sec;
+        t.tv_nsec += 1000000000;
+    }
+    return t;
+}
+
 struct config {
 #if 0 // unused for now
     fs::path dump_path{ "/var/lib/prelockdpp/dump.json" };


@@ 181,6 193,27 @@ struct context {
         }
         return t;
     }
+    auto tspec_from_ticks(auto ticks) {
+        timespec tspec;
+        tspec.tv_sec = ticks / info.sc_clk_tck;
+        tspec.tv_nsec = ticks % info.sc_clk_tck;
+        return tspec;
+    }
+    auto parse_timespec(auto begin, auto end) {
+        auto from_chars = [&](auto begin, auto end, auto& out) {
+            if (auto [_, ec] = std::from_chars(begin, end, out); ec != std::errc()) {
+                throw std::runtime_error{ "Failed to read timespec value" };
+            }
+        };
+        auto end1 = std::find(begin, end, '.');
+        if (end1 == end) {
+            throw std::logic_error{ "Unexpected timespec fmt" };
+        }
+        timespec t;
+        from_chars(begin, end1, t.tv_sec);
+        from_chars(end1 + 1, end, t.tv_nsec);
+        return t;
+    }
     auto get_uptime() {
         int fd = open("/proc/uptime", O_RDONLY);
         if (fd == -1) {


@@ 205,34 238,20 @@ struct context {
             total += r;
         }
 
-        auto from_chars = [&](auto begin, auto end, auto& out) {
-            if (auto [_, ec] = std::from_chars(begin, end, out); ec != std::errc()) {
-                throw std::runtime_error{ "Failed to read /proc/uptime value" };
-            }
-        };
 
         if (total > 0) {
-            auto begin = buffer;
-            auto end = begin + total;
-
-            auto end1 = std::find(begin, end, '.');
-            if (end1 == end) {
-                throw std::logic_error{ "Unexpected /proc/uptime fmt" };
-            }
-
-            timespec uptime;
-            from_chars(begin, end1, uptime.tv_sec);
-            from_chars(end1 + 1, begin, uptime.tv_nsec);
-            return uptime;
+            return parse_timespec(buffer, buffer + total);
         }
         throw std::logic_error{ "read(/proc/uptime) was empty" };
     }
+    // replace FILE part of path_buf with `file`
     constexpr auto fmt_proc_pid_file(std::string_view file) {
         auto end = std::copy(file.begin(), file.end(), pid_end);
         assert(end < std::end(path_buf));
         *end = '\0';
         return end;
     }
+    // return whether cgroup matches on any of specified regexes
     auto match_cgroup(std::string_view cgroup) {
         std::cout << "match_cgroup(" << cgroup << "): unimplemented\n";
         return true;


@@ 331,17 350,34 @@ struct context {
 
             std::cout << pid << '\n';
             with_uniq_id(path_buf, [&](auto start_time, auto prefix){
-                std::cout << "start_time: " << start_time << '\n';
-                std::cout << "prefix:     " << prefix << '\n';
+                auto start_time_ = [=,this] {
+                    unsigned long long ticks;
+                    auto [p, ec] = std::from_chars(
+                        start_time.begin(),
+                        start_time.end(),
+                        ticks
+                    );
+                    if (ec != std::errc()) {
+                        throw std::logic_error{ "Failed to parse start_time value" };
+                    }
+                    return tspec_from_ticks(ticks);
+                }();
+
+                std::cout << "prefix:            " << prefix << '\n';
+                std::cout << "start_time:        " << start_time << '\n';
+                std::cout << "start_time (tspc): " << start_time_.tv_sec << '.' << start_time_.tv_nsec << '\n';
             });
         }
         if (errno) {
             throw errno_exception("readdir(proc) failed", errno);
         }
 
+        auto m = tspec_diff(m0, get_clock_time(CLOCK_MONOTONIC));
+        auto p = tspec_diff(p0, get_clock_time(CLOCK_PROCESS_CPUTIME_ID));
+
         std::cout << "Uptime:         " << uptime.tv_sec << '.' << uptime.tv_nsec << '\n';
-        std::cout << "Monotonic time: " << m0.tv_sec << '.' << m0.tv_nsec << '\n';
-        std::cout << "Proc CPU  time: " << p0.tv_sec << '.' << p0.tv_nsec << '\n';
+        std::cout << "Monotonic time: " << m.tv_sec << '.' << m.tv_nsec << '\n';
+        std::cout << "Proc CPU  time: " << p.tv_sec << '.' << p.tv_nsec << '\n';
     }
 
     context(config& cfg):