processgroup.cpp

/*
 *  Copyright 2014 Google, Inc
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */

//#define LOG_NDEBUG 0
#define LOG_TAG "libprocessgroup"

#include <assert.h>
#include <dirent.h>
#include <errno.h>
#include <fcntl.h>
#include <inttypes.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>

#include <chrono>
#include <memory>
#include <mutex>
#include <set>
#include <string>
#include <thread>

#include <android-base/file.h>
#include <android-base/logging.h>
#include <android-base/properties.h>
#include <android-base/stringprintf.h>
#include <android-base/strings.h>
#include <private/android_filesystem_config.h>

#include <processgroup/processgroup.h>

using android::base::GetBoolProperty;
using android::base::StartsWith;
using android::base::StringPrintf;
using android::base::WriteStringToFile;

using namespace std::chrono_literals;

#define MEM_CGROUP_PATH "/dev/memcg/apps"
#define MEM_CGROUP_TASKS "/dev/memcg/apps/tasks"
#define ACCT_CGROUP_PATH "/acct"

#define PROCESSGROUP_CGROUP_PROCS_FILE "/cgroup.procs"

std::once_flag init_path_flag;

static const std::string& GetCgroupRootPath() {
    static std::string cgroup_root_path;
    std::call_once(init_path_flag, [&]() {
        // low-ram devices use per-app memcg by default, unlike high-end ones
        bool low_ram_device = GetBoolProperty("ro.config.low_ram", false);
        bool per_app_memcg =
            GetBoolProperty("ro.config.per_app_memcg", low_ram_device);