1 files changed, 117 insertions, 0 deletions
diff --git a/src/cgroups.cpp b/src/cgroups.cpp
new file mode 100644
index 0000000..8091195
--- /dev/null
+++ b/src/cgroups.cpp
@@ -0,0 +1,117 @@
+/* -*- tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+#include <config.h>
+#include "cgroups.h"
+#include "util.h"
+
+#include <map>
+#include <unordered_map>
+#include <utility>
+
+bool
+cgroups_enabled(void)
+{
+    static bool initialized = false;
+    static bool has_cgroups;
+
+    if (not initialized) {
+        initialized = true;
+        has_cgroups = Glib::file_test("/proc/cgroups", Glib::FileTest::FILE_TEST_EXISTS);
+    }
+
+    return has_cgroups;
+}
+
+
+
+static const std::pair<std::string, std::string> &
+parse_cgroup_line(const std::string& line) {
+
+    static std::unordered_map<std::string, std::pair<std::string, std::string>> line_cache;
+
+    auto it = line_cache.insert({line, {"", ""} });
+    if (it.second) { // inserted new
+        std::string::size_type cat_start, name_start;
+
+        if ((cat_start = line.find(':')) != std::string::npos
+            && (name_start = line.find(':', cat_start + 1)) != std::string::npos) {
+
+            // printf("%s %lu %lu\n", line.c_str(), cat_start, name_start);
+            auto cat = line.substr(cat_start + 1, name_start - cat_start - 1);
+            auto name = line.substr(name_start + 1);
+
+            // strip the name= prefix
+            if (cat.find("name=") == 0) {
+                cat.erase(0, 5);
+            }
+
+            if (!name.empty() && name != "/") {
+                it.first->second = {name, cat};
+            }
+        }
+    }
+
+    return it.first->second;
+}
+
+
+static const std::string&
+get_process_cgroup_string(pid_t pid) {
+
+    static std::unordered_map<std::string, std::string> file_cache{ {"", ""} };
+
+    /* read out of /proc/pid/cgroup */
+    auto path = "/proc/" + std::to_string(pid) + "/cgroup";
+    std::string text;
+
+    try {
+        text = Glib::file_get_contents(path);
+    } catch (...) {
+        return file_cache[""];
+    }
+
+    auto it = file_cache.insert({ text, "" });
+
+    if (it.second) { // inserted new
+
+        // name -> [cat...], sorted by name;
+        std::map<std::string, std::vector<std::string>> names;
+
+        std::string::size_type last = 0, eol;
+
+        // for each line in the file
+        while ((eol = text.find('\n', last)) != std::string::npos) {
+            auto line = text.substr(last, eol - last);
+            last = eol + 1;
+
+            const auto& p = parse_cgroup_line(line);
+            if (!p.first.empty()) {
+                names[p.first].push_back(p.second);
+            }
+        }
+
+
+        // name (cat1, cat2), ...
+        // sorted by name, categories
+        std::vector<std::string> groups;
+
+        for (auto& i : names) {
+            std::sort(begin(i.second), end(i.second));
+            std::string cats = procman::join(i.second, ", ");
+            groups.push_back(i.first + " (" + cats + ')');
+        }
+
+        it.first->second = procman::join(groups, ", ");
+    }
+
+    return it.first->second;
+}
+
+
+void get_process_cgroup_info(ProcInfo& info) {
+    if (not cgroups_enabled())
+        return;
+
+    const auto& cgroup_string = get_process_cgroup_string(info.pid);
+    info.cgroup_name = cgroup_string;
+}
+