// Copyright (c) Vitaliy Filippov, 2019+
// License: VNPL-1.1 or GNU GPL-2.0+ (see README.md for details)

/**
 * Stub "OSD" to test & compare network performance with sync read/write and io_uring
 *
 * Core i7-6700HQ laptop
 *
 * stub_osd:
 * randwrite Q1 S1: 36900 iops
 * randwrite Q32 S32: 71000 iops
 * randwrite Q32 S32 (multi-fsync fix): 113000 iops
 * randread Q1: 67300 iops
 * randread Q32: 144000 iops
 *
 * io_uring osd with #define OSD_STUB:
 * randwrite Q1 S1: 30000 iops
 * randwrite Q32 S32: 78600 iops
 * randwrite Q32 S32 (multi-fsync fix): 125000 iops
 * randread Q1: 50700 iops
 * randread Q32: 86100 iops
 *
 * It seems io_uring is fine :)
 */

#include <sys/types.h>
#include <sys/mman.h>
#include <sys/socket.h>
#include <poll.h>
#include <netinet/in.h>
#include <netinet/tcp.h>
#include <arpa/inet.h>
#include <string.h>
#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include <stdlib.h>

#include <stdexcept>

#include "addr_util.h"
#include "rw_blocking.h"
#include "osd_ops.h"

int bind_stub(std::string bind_address, int bind_port);

void run_stub(int peer_fd, int peer_data_fd);

int main(int narg, char *args[])
{
    int listen_fd = bind_stub("0.0.0.0", 11203);
    int listen_data_fd = bind_stub("0.0.0.0", 11204);
/*    int mss = 8192;
    if (setsockopt(listen_data_fd, IPPROTO_TCP, TCP_MAXSEG, &mss, sizeof(mss)) < 0)
    {
        throw std::runtime_error(std::string("setsockopt TCP_MAXSEG: ") + strerror(errno));
    }
    int rcvlowat = 4096;
    if (setsockopt(listen_data_fd, SOL_SOCKET, SO_RCVLOWAT, &rcvlowat, sizeof(rcvlowat)) < 0)
    {
        throw std::runtime_error(std::string("setsockopt SO_RCVLOWAT: ") + strerror(errno));
    }*/
    // Accept new connections
    sockaddr addr;
    socklen_t peer_addr_size;
    int peer_fd, peer_data_fd;
    const int one = 1;
    while (1)
    {
        printf("stub_osd: waiting for 1 client\n");
        peer_addr_size = sizeof(addr);
        peer_fd = accept(listen_fd, (sockaddr*)&addr, &peer_addr_size);
        if (peer_fd == -1)
        {
            if (errno == EAGAIN)
                continue;
            else
                throw std::runtime_error(std::string("accept: ") + strerror(errno));
        }
        setsockopt(peer_fd, SOL_TCP, TCP_NODELAY, &one, sizeof(one));
        printf("stub_osd: new client %d: connection from %s\n", peer_fd,
            addr_to_string(*((sockaddr*)&addr)).c_str());
        printf("stub_osd: waiting for 1 data connection\n");
        peer_addr_size = sizeof(addr);
        peer_data_fd = accept(listen_data_fd, (sockaddr*)&addr, &peer_addr_size);
        if (peer_data_fd == -1)
        {
            if (errno == EAGAIN)
                continue;
            else
                throw std::runtime_error(std::string("accept: ") + strerror(errno));
        }
        setsockopt(peer_data_fd, SOL_TCP, TCP_NODELAY, &one, sizeof(one));
        printf("stub_osd: new client %d: data connection from %s\n", peer_data_fd,
            addr_to_string(*((sockaddr*)&addr)).c_str());
        run_stub(peer_fd, peer_data_fd);
        close(peer_data_fd);
        close(peer_fd);
        printf("stub_osd: client %d / data %d disconnected\n", peer_fd, peer_data_fd);
        // Try to accept next connection
    }
    return 0;
}

int bind_stub(std::string bind_address, int bind_port)
{
    int listen_backlog = 128;

    sockaddr_storage addr = { 0 };
    if (!string_to_addr(bind_address, 0, bind_port, (sockaddr*)&addr))
    {
        throw std::runtime_error("bind address "+bind_address+" is not valid");
    }

    int listen_fd = socket(addr.ss_family, SOCK_STREAM, 0);
    if (listen_fd < 0)
    {
        throw std::runtime_error(std::string("socket: ") + strerror(errno));
    }
    int enable = 1;
    setsockopt(listen_fd, SOL_SOCKET, SO_REUSEADDR, &enable, sizeof(enable));

    if (bind(listen_fd, (sockaddr*)&addr, addr.ss_family == AF_INET ? sizeof(struct sockaddr_in) : sizeof(struct sockaddr_in6)) < 0)
    {
        close(listen_fd);
        throw std::runtime_error(std::string("bind: ") + strerror(errno));
    }

    if (listen(listen_fd, listen_backlog) < 0)
    {
        close(listen_fd);
        throw std::runtime_error(std::string("listen: ") + strerror(errno));
    }

    return listen_fd;
}

void run_stub(int peer_fd, int peer_data_fd)
{
    osd_any_op_t op;
    osd_any_reply_t reply = { 0 };
    unsigned bufsize = 4*1024*1024;
    void *buf = mmap(NULL, bufsize, PROT_READ, MAP_SHARED, peer_data_fd, 0);
    if (buf == MAP_FAILED)
    {
        throw std::runtime_error(std::string("mmap: ") + strerror(errno));
    }
    while (1)
    {
        int r = read_blocking(peer_fd, op.buf, OSD_PACKET_SIZE);
        if (r < OSD_PACKET_SIZE)
        {
            break;
        }
        if (op.hdr.magic != SECONDARY_OSD_OP_MAGIC)
        {
            printf("client %d: bad magic number in operation header\n", peer_fd);
            break;
        }
        reply.hdr.magic = SECONDARY_OSD_REPLY_MAGIC;
        reply.hdr.id = op.hdr.id;
        reply.hdr.opcode = op.hdr.opcode;
        if (op.hdr.opcode == OSD_OP_SEC_READ)
        {
            reply.hdr.retval = op.sec_rw.len;
            void *buf = malloc(op.sec_rw.len);
            r = write_blocking(peer_fd, reply.buf, OSD_PACKET_SIZE);
            if (r == OSD_PACKET_SIZE)
                r = write_blocking(peer_data_fd, buf, op.sec_rw.len);
            free(buf);
            if (r < op.sec_rw.len)
                break;
        }
        else if (op.hdr.opcode == OSD_OP_SEC_WRITE || op.hdr.opcode == OSD_OP_SEC_WRITE_STABLE)
        {
            struct pollfd pfd = { .fd = peer_data_fd, .events = POLLIN };
            poll(&pfd, 1, 10000);
            struct tcp_zerocopy_receive zc = { .address = (uint64_t)buf, .length = op.sec_rw.len };
            socklen_t zc_len = sizeof(zc);
            r = getsockopt(peer_data_fd, IPPROTO_TCP, TCP_ZEROCOPY_RECEIVE, &zc, &zc_len);
            r = r == -1 ? 0 : zc.length;
            if (r > 0)
            {
                uint64_t hash = 0;
                for (int k = 0; k < r/8; k++)
                    hash ^= ((uint64_t*)buf)[k];
                printf("ZCTR: op=%lx r=%d len=%d skip=%d hash=%lx\n", op.hdr.id, r, zc.length, zc.recv_skip_hint, hash);
            }
            if (r < op.sec_rw.len)
            {
                int rest = op.sec_rw.len - r;
                void *buf = malloc(rest);
                r += read_blocking(peer_data_fd, buf, rest);
                free(buf);
            }
            reply.hdr.retval = op.sec_rw.len;
            if (r == op.sec_rw.len)
                r = write_blocking(peer_fd, reply.buf, OSD_PACKET_SIZE);
            else
                r = 0;
            if (r < OSD_PACKET_SIZE)
                break;
        }
        else if (op.hdr.opcode == OSD_OP_TEST_SYNC_STAB_ALL)
        {
            reply.hdr.retval = 0;
            r = write_blocking(peer_fd, reply.buf, OSD_PACKET_SIZE);
            if (r < OSD_PACKET_SIZE)
                break;
        }
        else
        {
            printf("client %d: unsupported stub opcode: %lu\n", peer_fd, op.hdr.opcode);
            break;
        }
    }
}