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

#include "osd_primary.h"

#define SELF_FD -1

void osd_t::scrub_list(pool_pg_num_t pg_id, osd_num_t role_osd, object_id min_oid)
{
    pool_id_t pool_id = pg_id.pool_id;
    pg_num_t pg_num = pg_id.pg_num;
    assert(!scrub_list_op);
    if (role_osd == this->osd_num)
    {
        // Self
        osd_op_t *op = new osd_op_t();
        op->op_type = 0;
        op->peer_fd = SELF_FD;
        clock_gettime(CLOCK_REALTIME, &op->tv_begin);
        op->bs_op = new blockstore_op_t();
        op->bs_op->opcode = BS_OP_LIST;
        op->bs_op->pg_alignment = st_cli.pool_config[pool_id].pg_stripe_size;
        if (min_oid.inode != 0 || min_oid.stripe != 0)
            op->bs_op->min_oid = min_oid;
        else
            op->bs_op->min_oid.inode = ((uint64_t)pool_id << (64 - POOL_ID_BITS));
        op->bs_op->max_oid.inode = ((uint64_t)(pool_id+1) << (64 - POOL_ID_BITS)) - 1;
        op->bs_op->max_oid.stripe = UINT64_MAX;
        op->bs_op->list_stable_limit = scrub_list_limit;
        op->bs_op->pg_count = pg_counts[pool_id];
        op->bs_op->pg_number = pg_num-1;
        op->bs_op->callback = [this, op](blockstore_op_t *bs_op)
        {
            scrub_list_op = NULL;
            if (op->bs_op->retval < 0)
            {
                printf("Local OP_LIST failed: retval=%d\n", op->bs_op->retval);
                force_stop(1);
                return;
            }
            add_bs_subop_stats(op);
            scrub_cur_list = {
                .buf = (obj_ver_id*)op->bs_op->buf,
                .total_count = (uint64_t)op->bs_op->retval,
                .stable_count = op->bs_op->version,
            };
            delete op->bs_op;
            op->bs_op = NULL;
            delete op;
            continue_scrub();
        };
        scrub_list_op = op;
        bs->enqueue_op(op->bs_op);
    }
    else
    {
        // Peer
        osd_op_t *op = new osd_op_t();
        op->op_type = OSD_OP_OUT;
        op->peer_fd = msgr.osd_peer_fds.at(role_osd);
        op->req = (osd_any_op_t){
            .sec_list = {
                .header = {
                    .magic = SECONDARY_OSD_OP_MAGIC,
                    .id = msgr.next_subop_id++,
                    .opcode = OSD_OP_SEC_LIST,
                },
                .list_pg = pg_num,
                .pg_count = pg_counts[pool_id],
                .pg_stripe_size = st_cli.pool_config[pool_id].pg_stripe_size,
                .min_inode = min_oid.inode ? min_oid.inode : ((uint64_t)(pool_id) << (64 - POOL_ID_BITS)),
                .max_inode = ((uint64_t)(pool_id+1) << (64 - POOL_ID_BITS)) - 1,
                .min_stripe = min_oid.stripe,
                .stable_limit = scrub_list_limit,
            },
        };
        op->callback = [this, role_osd](osd_op_t *op)
        {
            scrub_list_op = NULL;
            if (op->reply.hdr.retval < 0)
            {
                printf("Failed to get object list from OSD %lu (retval=%ld), disconnecting peer\n", role_osd, op->reply.hdr.retval);
                int fail_fd = op->peer_fd;
                delete op;
                msgr.stop_client(fail_fd);
                return;
            }
            scrub_cur_list = {
                .buf = (obj_ver_id*)op->buf,
                .total_count = (uint64_t)op->reply.hdr.retval,
                .stable_count = op->reply.sec_list.stable_count,
            };
            // set op->buf to NULL so it doesn't get freed
            op->buf = NULL;
            delete op;
            continue_scrub();
        };
        scrub_list_op = op;
        msgr.outbox_push(op);
    }
}

bool osd_t::pick_next_scrub(object_id & next_oid)
{
    if (!pgs.size())
    {
        if (scrub_cur_list.buf)
        {
            free(scrub_cur_list.buf);
            scrub_cur_list = {};
            scrub_last_pg = {};
        }
        return false;
    }
    timespec tv_now;
    clock_gettime(CLOCK_REALTIME, &tv_now);
    bool rescan = scrub_last_pg.pool_id != 0 || scrub_last_pg.pg_num != 0;
    // Restart scanning from the same PG as the last time
    auto pg_it = pgs.lower_bound(scrub_last_pg);
    while (pg_it != pgs.end())
    {
        if (pg_it->second.state & PG_ACTIVE)
        {
            auto & pool_cfg = st_cli.pool_config.at(pg_it->first.pool_id);
            auto interval = pool_cfg.scrub_interval ? pool_cfg.scrub_interval : global_scrub_interval;
            if (pg_it->second.scrub_ts < tv_now.tv_sec-interval)
            {
                // Continue scrubbing from the next object
                if (scrub_last_pg == pg_it->first)
                {
                    while (scrub_list_pos < scrub_cur_list.total_count)
                    {
                        auto oid = scrub_cur_list.buf[scrub_list_pos].oid;
                        oid.stripe &= ~STRIPE_MASK;
                        scrub_list_pos++;
                        if (recovery_ops.find(oid) == recovery_ops.end() &&
                            scrub_ops.find(oid) == scrub_ops.end())
                        {
                            next_oid = oid;
                            if (!(pg_it->second.state & PG_SCRUBBING))
                            {
                                // Currently scrubbing this PG
                                pg_it->second.state = pg_it->second.state | PG_SCRUBBING;
                                report_pg_state(pg_it->second);
                            }
                            return true;
                        }
                    }
                }
                if (scrub_last_pg == pg_it->first &&
                    scrub_cur_list.total_count && scrub_list_pos >= scrub_cur_list.total_count &&
                    scrub_cur_list.stable_count < scrub_list_limit)
                {
                    // End of the list, mark this PG as scrubbed and go to the next PG
                }
                else
                {
                    // Continue listing
                    object_id scrub_last_oid;
                    if (scrub_last_pg != pg_it->first)
                        scrub_last_oid = (object_id){};
                    else if (scrub_cur_list.stable_count > 0)
                    {
                        scrub_last_oid = scrub_cur_list.buf[scrub_cur_list.stable_count-1].oid;
                        scrub_last_oid.stripe++;
                    }
                    osd_num_t scrub_osd = 0;
                    for (osd_num_t pg_osd: pg_it->second.cur_set)
                    {
                        if (pg_osd == this->osd_num || scrub_osd == 0)
                            scrub_osd = pg_osd;
                    }
                    if (!(pg_it->second.state & PG_SCRUBBING))
                    {
                        // Currently scrubbing this PG
                        pg_it->second.state = pg_it->second.state | PG_SCRUBBING;
                        report_pg_state(pg_it->second);
                    }
                    if (scrub_cur_list.buf)
                    {
                        free(scrub_cur_list.buf);
                        scrub_cur_list = {};
                        scrub_last_oid = {};
                    }
                    scrub_last_pg = pg_it->first;
                    scrub_list(pg_it->first, scrub_osd, scrub_last_oid);
                    return true;
                }
            }
            if (pg_it->second.state & PG_SCRUBBING)
            {
                pg_it->second.scrub_ts = tv_now.tv_sec;
                pg_it->second.state = pg_it->second.state & ~PG_SCRUBBING;
                pg_it->second.history_changed = true;
                report_pg_state(pg_it->second);
                schedule_scrub(pg_it->second);
            }
            // The list is definitely not needed anymore
            if (scrub_cur_list.buf)
            {
                free(scrub_cur_list.buf);
                scrub_cur_list = {};
            }
        }
        pg_it++;
        if (pg_it == pgs.end() && rescan)
        {
            // Scan one more time to guarantee that there are no PGs to scrub
            pg_it = pgs.begin();
            rescan = false;
        }
    }
    // Scanned all PGs - no more scrubs to do
    return false;
}

void osd_t::submit_scrub_op(object_id oid)
{
    auto osd_op = new osd_op_t();
    osd_op->op_type = OSD_OP_OUT;
    osd_op->req = (osd_any_op_t){
        .rw = {
            .header = {
                .magic = SECONDARY_OSD_OP_MAGIC,
                .id = 1,
                .opcode = OSD_OP_SCRUB,
            },
            .inode = oid.inode,
            .offset = oid.stripe,
            .len = 0,
        },
    };
    if (log_level > 2)
    {
        printf("Submitting scrub for %lx:%lx\n", oid.inode, oid.stripe);
    }
    osd_op->callback = [this](osd_op_t *osd_op)
    {
        object_id oid = { .inode = osd_op->req.rw.inode, .stripe = osd_op->req.rw.offset };
        if (osd_op->reply.hdr.retval < 0 && osd_op->reply.hdr.retval != -ENOENT)
        {
            // Scrub error
            printf(
                "Scrub failed with object %lx:%lx (PG %u/%u): error %ld\n",
                oid.inode, oid.stripe, INODE_POOL(oid.inode),
                map_to_pg(oid, st_cli.pool_config.at(INODE_POOL(oid.inode)).pg_stripe_size),
                osd_op->reply.hdr.retval
            );
        }
        else if (log_level > 2)
        {
            printf("Scrubbed %lx:%lx OK\n", oid.inode, oid.stripe);
        }
        delete osd_op;
        if (scrub_sleep_ms)
        {
            this->tfd->set_timer(scrub_sleep_ms, false, [this, oid](int timer_id)
            {
                scrub_ops.erase(oid);
                continue_scrub();
            });
        }
        else
        {
            scrub_ops.erase(oid);
            continue_scrub();
        }
    };
    scrub_ops[oid] = osd_op;
    exec_op(osd_op);
}

// Triggers scrub requests
// Scrub reads data from all replicas and compares it
// To scrub first we need to read objects listings
bool osd_t::continue_scrub()
{
    if (scrub_list_op)
    {
        return true;
    }
    while (scrub_ops.size() < scrub_queue_depth)
    {
        object_id oid;
        if (pick_next_scrub(oid))
            submit_scrub_op(oid);
        else
            return false;
    }
    return true;
}

void osd_t::schedule_scrub(pg_t & pg)
{
    auto & pool_cfg = st_cli.pool_config.at(pg.pool_id);
    auto interval = pool_cfg.scrub_interval ? pool_cfg.scrub_interval : global_scrub_interval;
    if (!scrub_nearest_ts || scrub_nearest_ts > pg.scrub_ts+interval)
    {
        scrub_nearest_ts = pg.scrub_ts+interval;
        timespec tv_now;
        clock_gettime(CLOCK_REALTIME, &tv_now);
        if (scrub_timer_id >= 0)
        {
            tfd->clear_timer(scrub_timer_id);
            scrub_timer_id = -1;
        }
        if (tv_now.tv_sec > scrub_nearest_ts)
        {
            scrub_nearest_ts = 0;
            peering_state = peering_state | OSD_SCRUBBING;
            ringloop->wakeup();
        }
        else
        {
            scrub_timer_id = tfd->set_timer((scrub_nearest_ts-tv_now.tv_sec)*1000, false, [this](int timer_id)
            {
                scrub_timer_id = -1;
                scrub_nearest_ts = 0;
                peering_state = peering_state | OSD_SCRUBBING;
                ringloop->wakeup();
            });
        }
    }
}

void osd_t::continue_primary_scrub(osd_op_t *cur_op)
{
    if (!cur_op->op_data && !prepare_primary_rw(cur_op))
        return;
    osd_primary_op_data_t *op_data = cur_op->op_data;
    if (op_data->st == 1)
        goto resume_1;
    else if (op_data->st == 2)
        goto resume_2;
    {
        auto & pg = pgs.at({ .pool_id = INODE_POOL(op_data->oid.inode), .pg_num = op_data->pg_num });
        // Determine version
        auto vo_it = pg.ver_override.find(op_data->oid);
        op_data->target_ver = vo_it != pg.ver_override.end() ? vo_it->second : UINT64_MAX;
        // PG may have degraded or misplaced objects
        op_data->prev_set = get_object_osd_set(pg, op_data->oid, &op_data->object_state);
        // Read all available chunks
        int n_copies = 0;
        op_data->degraded = false;
        for (int role = 0; role < op_data->pg_size; role++)
        {
            op_data->stripes[role].read_start = 0;
            op_data->stripes[role].read_end = bs_block_size;
            if (op_data->prev_set[role] != 0)
            {
                n_copies++;
            }
            else if (op_data->scheme != POOL_SCHEME_REPLICATED && role < op_data->pg_data_size)
            {
                op_data->degraded = true;
            }
        }
        if (n_copies <= op_data->pg_data_size)
        {
            // Nothing to compare, even if we'd like to
            finish_op(cur_op, 0);
            return;
        }
        cur_op->buf = alloc_read_buffer(op_data->stripes, op_data->pg_size,
            op_data->scheme != POOL_SCHEME_REPLICATED ? bs_block_size*(op_data->pg_size-op_data->pg_data_size) : 0);
        // Submit reads
        osd_op_t *subops = new osd_op_t[n_copies];
        op_data->fact_ver = 0;
        op_data->done = op_data->errors = op_data->errcode = 0;
        op_data->n_subops = n_copies;
        op_data->subops = subops;
        int sent = submit_primary_subop_batch(SUBMIT_SCRUB_READ, op_data->oid.inode, op_data->target_ver,
            op_data->stripes, op_data->prev_set, cur_op, 0, -1);
        assert(sent == n_copies);
        op_data->st = 1;
    }
resume_1:
    return;
resume_2:
    if (op_data->errors > 0)
    {
        if (op_data->errcode == -EIO || op_data->errcode == -EDOM)
        {
            // I/O or checksum error
            int n_copies = 0;
            for (int role = 0; role < op_data->pg_size; role++)
            {
                if (op_data->stripes[role].read_end != 0 &&
                    !op_data->stripes[role].read_error)
                {
                    n_copies++;
                }
            }
            if (n_copies <= op_data->pg_data_size)
            {
                // Nothing to compare, just mark the object as corrupted
                auto & pg = pgs.at({ .pool_id = INODE_POOL(op_data->oid.inode), .pg_num = op_data->pg_num });
                // FIXME: ref = true ideally... because new_state != state is not necessarily true if it's freed and recreated
                op_data->object_state = mark_object_corrupted(pg, op_data->oid, op_data->object_state, op_data->stripes, false);
                // Operation is treated as unsuccessful only if the object becomes unreadable
                finish_op(cur_op, n_copies < op_data->pg_data_size ? op_data->errcode : 0);
                return;
            }
            // Proceed, we can still compare chunks that were successfully read
        }
        else
        {
            finish_op(cur_op, op_data->errcode);
            return;
        }
    }
    if (op_data->scheme == POOL_SCHEME_REPLICATED)
    {
        // Check that all chunks have returned the same data
        int total = 0;
        int eq_to[op_data->pg_size];
        for (int role = 0; role < op_data->pg_size; role++)
        {
            eq_to[role] = -1;
            if (op_data->stripes[role].read_end != 0 && !op_data->stripes[role].read_error)
            {
                total++;
                eq_to[role] = role;
                for (int other = 0; other < role; other++)
                {
                    // Only compare with unique chunks (eq_to[other] == other)
                    if (eq_to[other] == other && memcmp(op_data->stripes[role].read_buf, op_data->stripes[other].read_buf, bs_block_size) == 0)
                    {
                        eq_to[role] = eq_to[other];
                        break;
                    }
                }
            }
        }
        int votes[op_data->pg_size];
        for (int role = 0; role < op_data->pg_size; role++)
            votes[role] = 0;
        for (int role = 0; role < op_data->pg_size; role++)
        {
            if (eq_to[role] != -1)
                votes[eq_to[role]]++;
        }
        int best = -1;
        for (int role = 0; role < op_data->pg_size; role++)
        {
            if (best < 0 && votes[role] > 0 || votes[role] > votes[best])
                best = role;
        }
        if (best > 0 && votes[best] < total)
        {
            // FIXME Add a flag to allow to skip such objects and not recover them automatically
            bool unknown = false;
            for (int role = 0; role < op_data->pg_size; role++)
            {
                if (role != best && votes[role] == votes[best])
                    unknown = true;
                if (votes[role] > 0 && votes[role] < votes[best])
                {
                    printf(
                        "[PG %u/%u] Object %lx:%lx copy on OSD %lu doesn't match %d other copies, marking it as corrupted\n",
                        INODE_POOL(op_data->oid.inode), op_data->pg_num,
                        op_data->oid.inode, op_data->oid.stripe, op_data->stripes[role].osd_num, votes[best]
                    );
                    op_data->stripes[role].read_error = true;
                }
            }
            if (unknown)
            {
                // It's unknown which replica is good. There are multiple versions with no majority
                best = -1;
            }
        }
    }
    else
    {
        assert(op_data->scheme == POOL_SCHEME_EC || op_data->scheme == POOL_SCHEME_XOR);
        if (op_data->degraded)
        {
            // Reconstruct missing stripes
            // XOR shouldn't come here as it only has 1 parity chunk
            assert(op_data->scheme == POOL_SCHEME_EC);
            reconstruct_stripes_ec(op_data->stripes, op_data->pg_size, op_data->pg_data_size, clean_entry_bitmap_size);
        }
        // Generate parity chunks and compare them with actual data
        osd_num_t fake_osd_set[op_data->pg_size];
        for (int i = 0; i < op_data->pg_size; i++)
        {
            fake_osd_set[i] = 1;
            op_data->stripes[i].write_buf = i >= op_data->pg_data_size
                ? ((uint8_t*)cur_op->buf + (i-op_data->pg_data_size)*bs_block_size)
                : op_data->stripes[i].read_buf;
        }
        if (op_data->scheme == POOL_SCHEME_XOR)
        {
            calc_rmw_parity_xor(op_data->stripes, op_data->pg_size, fake_osd_set, fake_osd_set, bs_block_size, clean_entry_bitmap_size);
        }
        else if (op_data->scheme == POOL_SCHEME_EC)
        {
            calc_rmw_parity_ec(op_data->stripes, op_data->pg_size, op_data->pg_data_size, fake_osd_set, fake_osd_set, bs_block_size, clean_entry_bitmap_size);
        }
        // Now compare that write_buf == read_buf
        for (int role = op_data->pg_data_size; role < op_data->pg_size; role++)
        {
            if (op_data->stripes[role].osd_num != 0 && !op_data->stripes[role].read_error &&
                memcmp(op_data->stripes[role].read_buf, op_data->stripes[role].write_buf, bs_block_size) != 0)
            {
                // Chunks don't match - something's wrong... but we don't know what :D
                // FIXME: Try to locate errors (may be possible with >= 2 parity chunks)
                printf(
                    "[PG %u/%u] Object %lx:%lx parity chunk %d on OSD %lu doesn't match data, marking it as corrupted\n",
                    INODE_POOL(op_data->oid.inode), op_data->pg_num,
                    op_data->oid.inode, op_data->oid.stripe,
                    role-op_data->pg_data_size, op_data->stripes[role].osd_num
                );
                op_data->stripes[role].read_error = true;
            }
        }
    }
    for (int role = 0; role < op_data->pg_size; role++)
    {
        if (op_data->stripes[role].osd_num != 0 && !op_data->stripes[role].read_error)
        {
            // Got at least 1 read error or mismatch, mark the object as corrupted
            auto & pg = pgs.at({ .pool_id = INODE_POOL(op_data->oid.inode), .pg_num = op_data->pg_num });
            // FIXME: ref = true ideally... because new_state != state is not necessarily true if it's freed and recreated
            op_data->object_state = mark_object_corrupted(pg, op_data->oid, op_data->object_state, op_data->stripes, false);
            break;
        }
    }
    finish_op(cur_op, 0);
}