Function createDiskBacklog

src/replication.cpp:190–220

/* ---------------------------------- MASTER -------------------------------- */

bool createDiskBacklog() {
    if (g_pserver->repl_backlog_disk != nullptr)
        return true;    // already exists
    // Lets create some disk backed pages and add them here
    std::string path = "./repl-backlog-temp" + std::to_string(gettid());
#if (defined __APPLE__ || defined __FreeBSD__)
    int fd = open(path.c_str(), O_CREAT | O_RDWR, S_IRUSR | S_IWUSR);
#else
    int fd = open(path.c_str(), O_CREAT | O_RDWR | O_LARGEFILE, S_IRUSR | S_IWUSR);
#endif
    if (fd < 0) {
        return false;
    }
    size_t alloc = cserver.repl_backlog_disk_size;
    int result = truncate(path.c_str(), alloc);
    unlink(path.c_str()); // ensure the fd is the only ref
    if (result == -1) {
        close (fd);
        return false;
    }

    g_pserver->repl_backlog_disk = (char*)mmap(nullptr, alloc, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
    close(fd);
    if (g_pserver->repl_backlog_disk == MAP_FAILED) {
        g_pserver->repl_backlog_disk = nullptr;
        return false;
    }

    serverLog(LL_VERBOSE, "Disk Backed Replication Allocated");
    return true;
}

void createReplicationBacklog(void) {
    serverAssert(g_pserver->repl_backlog == NULL);