Function get_fd_count

src/bvar/default_variables.cpp:338–377

// ==================================================

static int get_fd_count(int limit) {
#if defined(OS_LINUX)
    butil::DirReaderPosix dr("/proc/self/fd");
    int count = 0;
    if (!dr.IsValid()) {
        PLOG(WARNING) << "Fail to open /proc/self/fd";
        return -1;
    }
    // Have to limit the scaning which consumes a lot of CPU when #fd
    // are huge (100k+)
    for (; dr.Next() && count <= limit + 3; ++count) {}
    return count - 3 /* skipped ., .. and the fd in dr*/;
#elif defined(OS_MACOSX)
    // TODO(zhujiashun): following code will cause core dump with some 
    // probability under mac when program exits. Fix it.
    /* 
    static pid_t pid = getpid();
    std::ostringstream oss;
    char cmdbuf[128];
    snprintf(cmdbuf, sizeof(cmdbuf),
            "lsof -p %ld | grep -v \"txt\" | wc -l", (long)pid);
    if (butil::read_command_output(oss, cmdbuf) != 0) {
        LOG(ERROR) << "Fail to read open files";
        return -1;
    }
    const std::string& result = oss.str();
    int count = 0;
    if (sscanf(result.c_str(), "%d", &count) != 1) {
        PLOG(WARNING) << "Fail to sscanf";
        return -1;
    }
    // skipped . and first column line
    count = count - 2;
    return std::min(count, limit);
    */
    return 0;
#else
    return 0;
#endif
}

extern PassiveStatus<int> g_fd_num;