forward_metadata.cpp

/*
  Copyright 2018-2020, Barcelona Supercomputing Center (BSC), Spain
  Copyright 2015-2020, Johannes Gutenberg Universitaet Mainz, Germany

  This software was partially supported by the
  EC H2020 funded project NEXTGenIO (Project ID: 671951, www.nextgenio.eu).

  This software was partially supported by the
  ADA-FS project under the SPPEXA project funded by the DFG.

  SPDX-License-Identifier: MIT
*/

#include <client/rpc/forward_metadata.hpp>
#include <client/preload.hpp>
#include <client/logging.hpp>
#include <client/preload_util.hpp>
#include <client/open_dir.hpp>
#include <client/rpc/rpc_types.hpp>

#include <global/rpc/rpc_util.hpp>
#include <global/rpc/distributor.hpp>
#include <global/rpc/rpc_types.hpp>

using namespace std;

namespace gkfs {
namespace rpc {

int forward_create(const std::string& path, const mode_t mode) {

    int err = EUNKNOWN;
    auto endp = CTX->hosts().at(CTX->distributor()->locate_file_metadata(path));

    try {
        LOG(DEBUG, "Sending RPC ...");
        // TODO(amiranda): add a post() with RPC_TIMEOUT to hermes so that we can
        // retry for RPC_TRIES (see old commits with margo)
        // TODO(amiranda): hermes will eventually provide a post(endpoint)
        // returning one result and a broadcast(endpoint_set) returning a
        // result_set. When that happens we can remove the .at(0) :/
        auto out = ld_network_service->post<gkfs::rpc::create>(endp, path, mode).get().at(0);
        err = out.err();
        LOG(DEBUG, "Got response success: {}", err);

        if (out.err()) {
            errno = out.err();
            return -1;
        }

    } catch (const std::exception& ex) {
        LOG(ERROR, "while getting rpc output");
        errno = EBUSY;
        return -1;
    }

    return err;
}

int forward_stat(const std::string& path, string& attr) {

    auto endp = CTX->hosts().at(CTX->distributor()->locate_file_metadata(path));

    try {
        LOG(DEBUG, "Sending RPC ...");
        // TODO(amiranda): add a post() with RPC_TIMEOUT to hermes so that we can
        // retry for RPC_TRIES (see old commits with margo)
        // TODO(amiranda): hermes will eventually provide a post(endpoint)
        // returning one result and a broadcast(endpoint_set) returning a
        // result_set. When that happens we can remove the .at(0) :/
        auto out = ld_network_service->post<gkfs::rpc::stat>(endp, path).get().at(0);
        LOG(DEBUG, "Got response success: {}", out.err());

        if (out.err() != 0) {
            errno = out.err();
            return -1;
        }

        attr = out.db_val();
        return 0;

    } catch (const std::exception& ex) {
        LOG(ERROR, "while getting rpc output");
        errno = EBUSY;
        return -1;
    }

    return 0;
}

int forward_remove(const std::string& path, const bool remove_metadentry_only, const ssize_t size) {

    // if only the metadentry should be removed, send one rpc to the
    // metadentry's responsible node to remove the metadata
    // else, send an rpc to all hosts and thus broadcast chunk_removal.
    if (remove_metadentry_only) {

        auto endp = CTX->hosts().at(CTX->distributor()->locate_file_metadata(path));

        try {

            LOG(DEBUG, "Sending RPC ...");
            // TODO(amiranda): add a post() with RPC_TIMEOUT to hermes so that we can
            // retry for RPC_TRIES (see old commits with margo)
            // TODO(amiranda): hermes will eventually provide a post(endpoint)
            // returning one result and a broadcast(endpoint_set) returning a
            // result_set. When that happens we can remove the .at(0) :/
            auto out = ld_network_service->post<gkfs::rpc::remove>(endp, path).get().at(0);

            LOG(DEBUG, "Got response success: {}", out.err());

            if (out.err() != 0) {
                errno = out.err();
                return -1;
            }

            return 0;

        } catch (const std::exception& ex) {
            LOG(ERROR, "while getting rpc output");
            errno = EBUSY;
            return -1;
        }

        return 0;
    }

    std::vector<hermes::rpc_handle<gkfs::rpc::remove>> handles;

    // Small files
    if (static_cast<std::size_t>(size / gkfs::config::rpc::chunksize) < CTX->hosts().size()) {

        auto endp = CTX->hosts().at(CTX->distributor()->locate_file_metadata(path));

        try {
            LOG(DEBUG, "Sending RPC to host: {}", endp.to_string());
            gkfs::rpc::remove::input in(path);
            handles.emplace_back(ld_network_service->post<gkfs::rpc::remove>(endp, in));

            uint64_t chnk_start = 0;
            uint64_t chnk_end = size / gkfs::config::rpc::chunksize;

            for (uint64_t chnk_id = chnk_start; chnk_id <= chnk_end; chnk_id++) {
                const auto target = CTX->hosts().at(
                        CTX->distributor()->locate_data(path, chnk_id));

                LOG(DEBUG, "Sending RPC to host: {}", target.to_string());

                handles.emplace_back(ld_network_service->post<gkfs::rpc::remove>(target, in));
            }
        } catch (const std::exception& ex) {
            LOG(ERROR, "Failed to send reduced remove requests");
            throw std::runtime_error(
                    "Failed to forward non-blocking rpc request");
        }
    } else {    // "Big" files
        for (const auto& endp : CTX->hosts()) {
            try {
                LOG(DEBUG, "Sending RPC to host: {}", endp.to_string());

                gkfs::rpc::remove::input in(path);

                // TODO(amiranda): add a post() with RPC_TIMEOUT to hermes so that
                // we can retry for RPC_TRIES (see old commits with margo)
                // TODO(amiranda): hermes will eventually provide a post(endpoint)
                // returning one result and a broadcast(endpoint_set) returning a
                // result_set. When that happens we can remove the .at(0) :/
                //
                //

                handles.emplace_back(ld_network_service->post<gkfs::rpc::remove>(endp, in));

            } catch (const std::exception& ex) {
                // TODO(amiranda): we should cancel all previously posted requests
                // here, unfortunately, Hermes does not support it yet :/
                LOG(ERROR, "Failed to send request to host: {}",
                    endp.to_string());
                throw std::runtime_error(
                        "Failed to forward non-blocking rpc request");
            }
        }
    }
    // wait for RPC responses
    bool got_error = false;

    for (const auto& h : handles) {

        try {
            // XXX We might need a timeout here to not wait forever for an
            // output that never comes?
            auto out = h.get().at(0);

            if (out.err() != 0) {
                LOG(ERROR, "received error response: {}", out.err());
                got_error = true;
                errno = out.err();
            }
        } catch (const std::exception& ex) {
            LOG(ERROR, "while getting rpc output");
            got_error = true;
            errno = EBUSY;
        }
    }

    return got_error ? -1 : 0;
}

int forward_decr_size(const std::string& path, size_t length) {

    auto endp = CTX->hosts().at(CTX->distributor()->locate_file_metadata(path));

    try {

        LOG(DEBUG, "Sending RPC ...");
        // TODO(amiranda): add a post() with RPC_TIMEOUT to hermes so that we can
        // retry for RPC_TRIES (see old commits with margo)
        // TODO(amiranda): hermes will eventually provide a post(endpoint)
        // returning one result and a broadcast(endpoint_set) returning a
        // result_set. When that happens we can remove the .at(0) :/
        auto out = ld_network_service->post<gkfs::rpc::decr_size>(endp, path, length).get().at(0);

        LOG(DEBUG, "Got response success: {}", out.err());

        if (out.err() != 0) {
            errno = out.err();
            return -1;
        }

        return 0;

    } catch (const std::exception& ex) {
        LOG(ERROR, "while getting rpc output");
        errno = EBUSY;
        return -1;
    }
}

int forward_update_metadentry(const string& path, const gkfs::metadata::Metadata& md,
                              const gkfs::metadata::MetadentryUpdateFlags& md_flags) {

    auto endp = CTX->hosts().at(CTX->distributor()->locate_file_metadata(path));

    try {

        LOG(DEBUG, "Sending RPC ...");
        // TODO(amiranda): add a post() with RPC_TIMEOUT to hermes so that we can
        // retry for RPC_TRIES (see old commits with margo)
        // TODO(amiranda): hermes will eventually provide a post(endpoint)
        // returning one result and a broadcast(endpoint_set) returning a
        // result_set. When that happens we can remove the .at(0) :/
        auto out = ld_network_service->post<gkfs::rpc::update_metadentry>(
                endp,
                path,
                (md_flags.link_count ? md.link_count() : 0),
                /* mode */ 0,
                /* uid */  0,
                /* gid */  0,
                (md_flags.size ? md.size() : 0),
                (md_flags.blocks ? md.blocks() : 0),
                (md_flags.atime ? md.atime() : 0),
                (md_flags.mtime ? md.mtime() : 0),
                (md_flags.ctime ? md.ctime() : 0),
                bool_to_merc_bool(md_flags.link_count),
                /* mode_flag */ false,
                bool_to_merc_bool(md_flags.size),
                bool_to_merc_bool(md_flags.blocks),
                bool_to_merc_bool(md_flags.atime),
                bool_to_merc_bool(md_flags.mtime),
                bool_to_merc_bool(md_flags.ctime)).get().at(0);

        LOG(DEBUG, "Got response success: {}", out.err());

        if (out.err() != 0) {
            errno = out.err();
            return -1;
        }

        return 0;

    } catch (const std::exception& ex) {
        LOG(ERROR, "while getting rpc output");
        errno = EBUSY;
        return -1;
    }
}

int
forward_update_metadentry_size(const string& path, const size_t size, const off64_t offset, const bool append_flag,
                               off64_t& ret_size) {

    auto endp = CTX->hosts().at(CTX->distributor()->locate_file_metadata(path));

    try {

        LOG(DEBUG, "Sending RPC ...");
        // TODO(amiranda): add a post() with RPC_TIMEOUT to hermes so that we can
        // retry for RPC_TRIES (see old commits with margo)
        // TODO(amiranda): hermes will eventually provide a post(endpoint)
        // returning one result and a broadcast(endpoint_set) returning a
        // result_set. When that happens we can remove the .at(0) :/
        auto out = ld_network_service->post<gkfs::rpc::update_metadentry_size>(
                endp, path, size, offset,
                bool_to_merc_bool(append_flag)).get().at(0);

        LOG(DEBUG, "Got response success: {}", out.err());

        if (out.err() != 0) {
            errno = out.err();
            return -1;
        }

        ret_size = out.ret_size();
        return out.err();

        return 0;

    } catch (const std::exception& ex) {
        LOG(ERROR, "while getting rpc output");
        errno = EBUSY;
        ret_size = 0;
        return EUNKNOWN;
    }
}

int forward_get_metadentry_size(const std::string& path, off64_t& ret_size) {

    auto endp = CTX->hosts().at(CTX->distributor()->locate_file_metadata(path));

    try {

        LOG(DEBUG, "Sending RPC ...");
        // TODO(amiranda): add a post() with RPC_TIMEOUT to hermes so that we can
        // retry for RPC_TRIES (see old commits with margo)
        // TODO(amiranda): hermes will eventually provide a post(endpoint)
        // returning one result and a broadcast(endpoint_set) returning a
        // result_set. When that happens we can remove the .at(0) :/
        auto out = ld_network_service->post<gkfs::rpc::get_metadentry_size>(endp, path).get().at(0);

        LOG(DEBUG, "Got response success: {}", out.err());

        ret_size = out.ret_size();
        return out.err();

    } catch (const std::exception& ex) {
        LOG(ERROR, "while getting rpc output");
        errno = EBUSY;
        ret_size = 0;
        return EUNKNOWN;
    }
}

/**
 * Sends an RPC request to a specific node to push all chunks that belong to him
 */
void forward_get_dirents(gkfs::filemap::OpenDir& open_dir) {

    auto const root_dir = open_dir.path();
    auto const targets = CTX->distributor()->locate_directory_metadata(root_dir);

    /* preallocate receiving buffer. The actual size is not known yet.
     *
     * On C++14 make_unique function also zeroes the newly allocated buffer.
     * It turns out that this operation is increadibly slow for such a big
     * buffer. Moreover we don't need a zeroed buffer here.
     */
    auto large_buffer = std::unique_ptr<char[]>(new char[gkfs::config::rpc::dirents_buff_size]);

    //XXX there is a rounding error here depending on the number of targets...
    const std::size_t per_host_buff_size = gkfs::config::rpc::dirents_buff_size / targets.size();

    // expose local buffers for RMA from servers
    std::vector<hermes::exposed_memory> exposed_buffers;
    exposed_buffers.reserve(targets.size());

    for (std::size_t i = 0; i < targets.size(); ++i) {
        try {
            exposed_buffers.emplace_back(ld_network_service->expose(
                    std::vector<hermes::mutable_buffer>{
                            hermes::mutable_buffer{
                                    large_buffer.get() + (i * per_host_buff_size),
                                    per_host_buff_size
                            }
                    },
                    hermes::access_mode::write_only));
        } catch (const std::exception& ex) {
            throw std::runtime_error("Failed to expose buffers for RMA");
        }
    }

    // send RPCs
    std::vector<hermes::rpc_handle<gkfs::rpc::get_dirents>> handles;

    for (std::size_t i = 0; i < targets.size(); ++i) {

        LOG(DEBUG, "target_host: {}", targets[i]);

        // Setup rpc input parameters for each host
        auto endp = CTX->hosts().at(targets[i]);

        gkfs::rpc::get_dirents::input in(root_dir, exposed_buffers[i]);

        try {

            LOG(DEBUG, "Sending RPC to host: {}", targets[i]);
            handles.emplace_back(ld_network_service->post<gkfs::rpc::get_dirents>(endp, in));
        } catch (const std::exception& ex) {
            LOG(ERROR, "Unable to send non-blocking get_dirents() "
                       "on {} [peer: {}]", root_dir, targets[i]);
            throw std::runtime_error("Failed to post non-blocking RPC request");
        }
    }

    // wait for RPC responses
    for (std::size_t i = 0; i < handles.size(); ++i) {

        gkfs::rpc::get_dirents::output out;

        try {
            // XXX We might need a timeout here to not wait forever for an
            // output that never comes?
            out = handles[i].get().at(0);

            if (out.err() != 0) {
                throw std::runtime_error(
                        fmt::format("Failed to retrieve dir entries from "
                                    "host '{}'. Error '{}', path '{}'",
                                    targets[i], strerror(out.err()), root_dir));
            }
        } catch (const std::exception& ex) {
            throw std::runtime_error(
                    fmt::format("Failed to get rpc output.. [path: {}, "
                                "target host: {}]", root_dir, targets[i]));
        }

        // each server wrote information to its pre-defined region in
        // large_buffer, recover it by computing the base_address for each
        // particular server and adding the appropriate offsets
        assert(exposed_buffers[i].count() == 1);
        void* base_ptr = exposed_buffers[i].begin()->data();

        bool* bool_ptr = reinterpret_cast<bool*>(base_ptr);
        char* names_ptr = reinterpret_cast<char*>(base_ptr) +
                          (out.dirents_size() * sizeof(bool));

        for (std::size_t j = 0; j < out.dirents_size(); j++) {

            gkfs::filemap::FileType ftype = (*bool_ptr) ? gkfs::filemap::FileType::directory
                                                        : gkfs::filemap::FileType::regular;
            bool_ptr++;

            // Check that we are not outside the recv_buff for this specific host
            assert((names_ptr - reinterpret_cast<char*>(base_ptr)) > 0);
            assert(static_cast<unsigned long int>(names_ptr - reinterpret_cast<char*>(base_ptr)) < per_host_buff_size);

            auto name = std::string(names_ptr);
            names_ptr += name.size() + 1;

            open_dir.add(name, ftype);
        }
    }
}

#ifdef HAS_SYMLINKS

int forward_mk_symlink(const std::string& path, const std::string& target_path) {

    auto endp = CTX->hosts().at(CTX->distributor()->locate_file_metadata(path));

    try {

        LOG(DEBUG, "Sending RPC ...");
        // TODO(amiranda): add a post() with RPC_TIMEOUT to hermes so that we can
        // retry for RPC_TRIES (see old commits with margo)
        // TODO(amiranda): hermes will eventually provide a post(endpoint)
        // returning one result and a broadcast(endpoint_set) returning a
        // result_set. When that happens we can remove the .at(0) :/
        auto out = ld_network_service->post<gkfs::rpc::mk_symlink>(endp, path, target_path).get().at(0);

        LOG(DEBUG, "Got response success: {}", out.err());

        if (out.err() != 0) {
            errno = out.err();
            return -1;
        }

        return 0;

    } catch (const std::exception& ex) {
        LOG(ERROR, "while getting rpc output");
        errno = EBUSY;
        return -1;
    }
}

#endif

} // namespace rpc
} // namespace gkfs