READY: Optimize create, stat, remove operations

Marc Vefrequested to merge
94-remove-exist-check-when-creating-a-file into master

Optimization of create, stat, and remove operations. The following changes have been made:

  • gkfs_open() logic refactored.
  • create: Previously a stat RPC was send before each create to make sure the file doesn't exist. This logic is now implicit in the create operation on the daemon side.
  • get_metadata() was used on the client for all stat operation, creating a shared_ptr for the Metadata object in the process which was not needed. A new function get_metadata_attr() was created to only return the metadata binary string, which will only create the metadata object if actually required.
  • Remove logic was separated into two operations: remove_metadata() and remove_data().
  • gkfs::config::metadata::implicit_data_removal setting: If true, will remove data on the same node during the remove_metadata() RPC. This is mainly an optimization, but will be useful for future asynchronous removal implementations.

Previously, the code path looked like this:

  1. stat() to get size and mode.
  2. Use these fields to determine if data needs to be removed or just metadata.
  3. remove() is called which, first, sends a single RPC to the daemon with the metadata. Afterwards, data is removed.
  4. The daemon used one handler for both cases.

It now looks like this:

  1. remove() is called which, first, sends a single RPC to the daemon with the metadata. Before, removing the metadata, the daemon fetches mode and size. If implicit_data_removal is set as a configuration, the data is removed in this RPC as well. mode and size are returned to the client.
  2. The client determines if data needs to be removed as well.
  3. If yes, sends a remove_data() RPC as it was previously.

Depends on !66 (merged) and !74 (merged).

Closes #94 (closed)

Edited by Alberto Miranda

Merge request reports

include/client/rpc/forward_metadata.hpp

+1 −2
Changes for include/client/rpc/forward_metadata.hpp: 1 added line, 2 removed lines.
Original line number Diff line number Diff line
@@ -41,8 +41,7 @@ int 
forward_stat(const std::string& path, std::string& attr);



int

forward_remove(const std::string& path, bool remove_metadentry_only,

               ssize_t size);

forward_remove(const std::string& path);



int

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

include/client/rpc/rpc_types.hpp

+134 −10
Changes for include/client/rpc/rpc_types.hpp: 134 added lines, 10 removed lines.
Original line number Diff line number Diff line
@@ -462,8 +462,8 @@ struct stat { 
};



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

// definitions for remove

struct remove {

// definitions for remove metadata

struct remove_metadata {



    // forward declarations of public input/output types for this RPC

    class input;
@@ -471,23 +471,23 @@ struct remove { 
    class output;



    // traits used so that the engine knows what to do with the RPC

    using self_type = remove;

    using self_type = remove_metadata;

    using handle_type = hermes::rpc_handle<self_type>;

    using input_type = input;

    using output_type = output;

    using mercury_input_type = rpc_rm_node_in_t;

    using mercury_output_type = rpc_err_out_t;

    using mercury_output_type = rpc_rm_metadata_out_t;



    // RPC public identifier

    // (N.B: we reuse the same IDs assigned by Margo so that the daemon

    // understands Hermes RPCs)

    constexpr static const uint64_t public_id = 2549415936;

    constexpr static const uint64_t public_id = 2087845888;



    // RPC internal Mercury identifier

    constexpr static const hg_id_t mercury_id = public_id;



    // RPC name

    constexpr static const auto name = gkfs::rpc::tag::remove;

    constexpr static const auto name = gkfs::rpc::tag::remove_metadata;



    // requires response?

    constexpr static const auto requires_response = true;
@@ -498,7 +498,7 @@ struct remove { 


    // Mercury callback to serialize output arguments

    constexpr static const auto mercury_out_proc_cb =

            HG_GEN_PROC_NAME(rpc_err_out_t);

            HG_GEN_PROC_NAME(rpc_rm_metadata_out_t);



    class input {
@@ -541,9 +541,10 @@ struct remove { 
        hermes::detail::post_to_mercury(ExecutionContext*);



    public:

        output() : m_err() {}

        output() : m_err(), m_size(), m_mode() {}



        output(int32_t err) : m_err(err) {}

        output(int32_t err, int64_t size, uint32_t mode)

            : m_err(err), m_size(size), m_mode(mode) {}



        output(output&& rhs) = default;
@@ -555,8 +556,10 @@ struct remove { 
        output&

        operator=(const output& other) = default;



        explicit output(const rpc_err_out_t& out) {

        explicit output(const rpc_rm_metadata_out_t& out) {

            m_err = out.err;

            m_size = out.size;

            m_mode = out.mode;

        }



        int32_t
@@ -564,8 +567,21 @@ struct remove { 
            return m_err;

        }



        int64_t

        size() const {

            return m_size;

        }



        uint32_t

        mode() const {

            return m_mode;

        };





    private:

        int32_t m_err;

        int64_t m_size;

        uint32_t m_mode;

    };

};
@@ -1285,6 +1301,114 @@ struct mk_symlink { 


#endif // HAS_SYMLINKS



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

// definitions for remove data

struct remove_data {



    // forward declarations of public input/output types for this RPC

    class input;



    class output;



    // traits used so that the engine knows what to do with the RPC

    using self_type = remove_data;

    using handle_type = hermes::rpc_handle<self_type>;

    using input_type = input;

    using output_type = output;

    using mercury_input_type = rpc_rm_node_in_t;

    using mercury_output_type = rpc_err_out_t;



    // RPC public identifier

    // (N.B: we reuse the same IDs assigned by Margo so that the daemon

    // understands Hermes RPCs)

    constexpr static const uint64_t public_id = 2649292800;



    // RPC internal Mercury identifier

    constexpr static const hg_id_t mercury_id = public_id;



    // RPC name

    constexpr static const auto name = gkfs::rpc::tag::remove_data;



    // requires response?

    constexpr static const auto requires_response = true;



    // Mercury callback to serialize input arguments

    constexpr static const auto mercury_in_proc_cb =

            HG_GEN_PROC_NAME(rpc_rm_node_in_t);



    // Mercury callback to serialize output arguments

    constexpr static const auto mercury_out_proc_cb =

            HG_GEN_PROC_NAME(rpc_err_out_t);



    class input {



        template <typename ExecutionContext>

        friend hg_return_t

        hermes::detail::post_to_mercury(ExecutionContext*);



    public:

        input(const std::string& path) : m_path(path) {}



        input(input&& rhs) = default;



        input(const input& other) = default;



        input&

        operator=(input&& rhs) = default;



        input&

        operator=(const input& other) = default;



        std::string

        path() const {

            return m_path;

        }



        explicit input(const rpc_rm_node_in_t& other) : m_path(other.path) {}



        explicit operator rpc_rm_node_in_t() {

            return {m_path.c_str()};

        }



    private:

        std::string m_path;

    };



    class output {



        template <typename ExecutionContext>

        friend hg_return_t

        hermes::detail::post_to_mercury(ExecutionContext*);



    public:

        output() : m_err() {}



        output(int32_t err) : m_err(err) {}



        output(output&& rhs) = default;



        output(const output& other) = default;



        output&

        operator=(output&& rhs) = default;



        output&

        operator=(const output& other) = default;



        explicit output(const rpc_err_out_t& out) {

            m_err = out.err;

        }



        int32_t

        err() const {

            return m_err;

        }



    private:

        int32_t m_err;

    };

};



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

// definitions for write_data

struct write_data {

include/client/preload_util.hpp

+1 −1
Changes for include/client/preload_util.hpp: 1 added line, 1 removed line.
Original line number Diff line number Diff line
@@ -55,7 +55,7 @@ to_underlying(E e) { 
    return static_cast<typename std::underlying_type<E>::type>(e);

}



std::shared_ptr<gkfs::metadata::Metadata>

std::optional<gkfs::metadata::Metadata>

get_metadata(const std::string& path, bool follow_links = false);



int

include/daemon/backend/metadata/db.hpp

+4 −1
Changes for include/daemon/backend/metadata/db.hpp: 4 added lines, 1 removed line.
Original line number Diff line number Diff line
@@ -37,7 +37,7 @@ public: 
    static inline void

    throw_rdb_status_excpt(const rdb::Status& s);



    MetadataDB(const std::string& path);

    explicit MetadataDB(const std::string& path);



    std::string

    get(const std::string& key) const;
@@ -45,6 +45,9 @@ public: 
    void

    put(const std::string& key, const std::string& val);



    void

    put_no_exist(const std::string& key, const std::string& val);



    void

    remove(const std::string& key);

include/daemon/backend/exceptions.hpp

+5 −0
Changes for include/daemon/backend/exceptions.hpp: 5 added lines, 0 removed lines.
Original line number Diff line number Diff line
@@ -30,6 +30,11 @@ public: 
    explicit NotFoundException(const std::string& s) : DBException(s){};

};



class ExistsException : public DBException {

public:

    explicit ExistsException(const std::string& s) : DBException(s){};

};



} // namespace metadata

} // namespace gkfs