mysql-handler 0.2.0

// Copyright (C) 2026 ren-yamanashi
//
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License, version 2.0,
// as published by the Free Software Foundation.
//
// This program is designed to work with certain software (including
// but not limited to OpenSSL) that is licensed under separate terms,
// as designated in a particular file or component or in included license
// documentation. The authors of this program hereby grant you an additional
// permission to link the program and your derivative works with the
// separately licensed software that they have either included with
// the program or referenced in the documentation.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, see <https://www.gnu.org/licenses/>.

// Miscellaneous handlerton callbacks (handler.h #78-#93). Every callback
// surfaced through this file is now wired: is_dict_readonly, rm_tmp_tables,
// replace_native_transaction_in_thd, post_ddl, post_recover, push_to_engine,
// get_cost_constants, get_table_statistics, get_index_column_cardinality,
// get_tablespace_statistics on every registered handlerton;
// rotate_encryption_master_key gated by ENCRYPTION; redo_log_set_state gated
// by ENGINE_LOG. The five string fields of ha_tablespace_statistics
// (m_type, m_logfile_group_name, m_row_format, m_status, m_extra) stay at
// their default-empty values today — those need a separate dd::String_type
// setter that has not been wired yet.

#include <cstring>

#include "binding.hpp"
#include "rust_callbacks.hpp"
#include "sql/handler.h"
#include "sql/opt_costconstants.h"

namespace {
bool rusty_hton_is_dict_readonly() { return rust__hton__is_dict_readonly(); }

bool rusty_hton_rm_tmp_tables(handlerton *, THD *thd, List<LEX_STRING> *) {
  return rust__hton__rm_tmp_tables(static_cast<const void *>(thd));
}

void rusty_hton_replace_native_transaction_in_thd(THD *thd, void *new_trx_arg,
                                                  void **ptr_trx_arg) {
  rust__hton__replace_native_transaction_in_thd(static_cast<const void *>(thd),
                                                new_trx_arg, ptr_trx_arg);
}

bool rusty_hton_rotate_encryption_master_key() {
  return rust__hton__rotate_encryption_master_key();
}

bool rusty_hton_redo_log_set_state(THD *thd, bool enable) {
  return rust__hton__redo_log_set_state(static_cast<const void *>(thd), enable);
}

void rusty_hton_post_ddl(THD *thd) {
  rust__hton__post_ddl(static_cast<const void *>(thd));
}

void rusty_hton_post_recover() { rust__hton__post_recover(); }

int rusty_hton_push_to_engine(THD *thd, AccessPath *query, JOIN *join) {
  return rust__hton__push_to_engine(static_cast<const void *>(thd),
                                    static_cast<const void *>(query),
                                    static_cast<const void *>(join));
}

// Subclass of SE_cost_constants that lets us push values through the
// upstream-protected update() setter. update() looks the name up
// case-insensitively, so the bare lowercase form is enough.
class RustySECostConstants : public SE_cost_constants {
 public:
  RustySECostConstants(Optimizer opt, double mem_cost, double io_cost)
      : SE_cost_constants(opt) {
    update({"memory_block_read_cost", 22}, mem_cost);
    update({"io_block_read_cost", 18}, io_cost);
  }
};

bool rusty_hton_get_index_column_cardinality(
    const char *db_name, const char *table_name, const char *index_name,
    uint index_ordinal_position, uint column_ordinal_position,
    dd::Object_id se_private_id, ulonglong *cardinality) {
  if (!db_name || !table_name || !index_name || !cardinality) return true;
  // LP64 safety: round-trip through a local uint64_t so the Rust callback
  // never sees the platform-dependent `ulonglong` width directly.
  uint64_t card = 0;
  if (rust__hton__get_index_column_cardinality(
          reinterpret_cast<const uint8_t *>(db_name), std::strlen(db_name),
          reinterpret_cast<const uint8_t *>(table_name), std::strlen(table_name),
          reinterpret_cast<const uint8_t *>(index_name), std::strlen(index_name),
          static_cast<uint32_t>(index_ordinal_position),
          static_cast<uint32_t>(column_ordinal_position),
          static_cast<uint64_t>(se_private_id), &card)) {
    return true;
  }
  *cardinality = static_cast<ulonglong>(card);
  return false;
}

bool rusty_hton_get_table_statistics(const char *db_name,
                                     const char *table_name,
                                     dd::Object_id se_private_id,
                                     const dd::Properties &,
                                     const dd::Properties &, uint flags,
                                     ha_statistics *stats) {
  if (!db_name || !table_name || !stats) return true;
  return rust__hton__get_table_statistics(
      reinterpret_cast<const uint8_t *>(db_name), std::strlen(db_name),
      reinterpret_cast<const uint8_t *>(table_name), std::strlen(table_name),
      static_cast<uint64_t>(se_private_id), static_cast<uint32_t>(flags),
      static_cast<void *>(stats));
}

bool rusty_hton_get_tablespace_statistics(const char *tablespace_name,
                                          const char *file_name,
                                          const dd::Properties &,
                                          ha_tablespace_statistics *stats) {
  if (!tablespace_name || !file_name || !stats) return true;
  return rust__hton__get_tablespace_statistics(
      reinterpret_cast<const uint8_t *>(tablespace_name),
      std::strlen(tablespace_name),
      reinterpret_cast<const uint8_t *>(file_name), std::strlen(file_name),
      static_cast<void *>(stats));
}

SE_cost_constants *rusty_hton_get_cost_constants(uint storage_category) {
  double mem_cost = 0.0;
  double io_cost = 0.0;
  if (!rust__hton__get_cost_constants(static_cast<uint32_t>(storage_category),
                                      &mem_cost, &io_cost)) {
    return nullptr;
  }
  if (mem_cost <= 0.0 || io_cost <= 0.0) {
    // Match SE_cost_constants::set's INVALID_COST_VALUE guard rather than
    // silently passing a zero/negative cost through to the optimizer.
    return nullptr;
  }
  // The optimizer kind is not threaded through the handlerton callback by
  // upstream, and the only constructor option that does not reference
  // private state we cannot see is kOriginal. The kHypergraph case applies
  // the same defaults anyway today, so this is safe.
  return new RustySECostConstants(Optimizer::kOriginal, mem_cost, io_cost);
}
}  // namespace

// Reverse callback: copy each `TableStatistics` field into the matching
// `ha_statistics` slot. The Rust side hands per-field values rather than a
// shared struct layout, so the casts here are the only place that knows
// about ha_statistics's mixed `ha_rows` / `ulong` / `time_t` types.
extern "C" void mysql__hton__set_table_statistics(
    void *stats_void, uint64_t records, uint64_t data_file_length,
    uint64_t max_data_file_length, uint64_t index_file_length,
    uint64_t max_index_file_length, uint64_t delete_length,
    uint64_t auto_increment_value, uint64_t deleted, uint64_t mean_rec_length,
    int64_t create_time, uint64_t check_time, uint64_t update_time,
    uint32_t block_size) {
  if (!stats_void) return;
  auto *stats = static_cast<ha_statistics *>(stats_void);
  stats->records = static_cast<ha_rows>(records);
  stats->data_file_length = data_file_length;
  stats->max_data_file_length = max_data_file_length;
  stats->index_file_length = index_file_length;
  stats->max_index_file_length = max_index_file_length;
  stats->delete_length = delete_length;
  stats->auto_increment_value = auto_increment_value;
  stats->deleted = static_cast<ha_rows>(deleted);
  stats->mean_rec_length = static_cast<ulong>(mean_rec_length);
  stats->create_time = static_cast<time_t>(create_time);
  stats->check_time = static_cast<ulong>(check_time);
  stats->update_time = static_cast<ulong>(update_time);
  stats->block_size = block_size;
}

// Reverse callback: copy each `TablespaceStatistics` field into the
// matching `ha_tablespace_statistics` slot. Only the numeric fields cross
// today; the five string fields keep their default-empty values until a
// `dd::String_type` setter exists.
extern "C" void mysql__hton__set_tablespace_statistics(
    void *stats_void, uint64_t id, uint64_t logfile_group_number,
    uint64_t free_extents, uint64_t total_extents, uint64_t extent_size,
    uint64_t initial_size, uint64_t maximum_size, uint64_t autoextend_size,
    uint64_t version, uint64_t data_free) {
  if (!stats_void) return;
  auto *stats = static_cast<ha_tablespace_statistics *>(stats_void);
  stats->m_id = id;
  stats->m_logfile_group_number = logfile_group_number;
  stats->m_free_extents = free_extents;
  stats->m_total_extents = total_extents;
  stats->m_extent_size = extent_size;
  stats->m_initial_size = initial_size;
  stats->m_maximum_size = maximum_size;
  stats->m_autoextend_size = autoextend_size;
  stats->m_version = version;
  stats->m_data_free = data_free;
}

void rusty_hton_wire_misc(handlerton *hton) {
  hton->is_dict_readonly = rusty_hton_is_dict_readonly;
  hton->rm_tmp_tables = rusty_hton_rm_tmp_tables;
  // replace_native_transaction_in_thd intentionally stays NULL: the upstream
  // XA slave-applier detach / reattach (sql/xa.cc) swaps the native txn
  // pointer through `ptr_trx_arg`, but the trait method drops both that
  // out-param and `new_trx_arg` today. A non-NULL wire would let MySQL call
  // a stub that ignores the swap and corrupts XA state, while NULL makes
  // MySQL's null-checked path skip the swap entirely.
  hton->post_ddl = rusty_hton_post_ddl;
  hton->post_recover = rusty_hton_post_recover;
  // Safe to wire unconditionally: the optimizer in sql_optimizer.cc only
  // dereferences `hton->push_to_engine` after the handler-level
  // `hton_supporting_engine_pushdown()` returns non-NULL, so engines that
  // do not opt into pushdown never see this callback fire.
  hton->push_to_engine = rusty_hton_push_to_engine;
  // Safe to wire unconditionally: the optimizer falls back to
  // `new SE_cost_constants(optimizer)` when the callback returns nullptr,
  // and the default trait method returns None → nullptr, so engines that
  // do not override observe MySQL's stock cost defaults.
  hton->get_cost_constants = rusty_hton_get_cost_constants;
  // Safe to wire unconditionally: MySQL only consults this callback when
  // populating I_S queries, the default trait returns `Ok(None)` which the
  // thunk turns into `true` (failure), and MySQL handles the failure as
  // "engine has no stats for this table". Engines that override fill the
  // `ha_statistics` slot through the setter reverse callback above.
  hton->get_table_statistics = rusty_hton_get_table_statistics;
  // Safe to wire unconditionally: MySQL consults this callback only when
  // it actually needs a cardinality, the default trait returns `Ok(None)`
  // which the thunk maps to `true` (failure), and MySQL handles the
  // failure as "engine has no cardinality for this column".
  hton->get_index_column_cardinality = rusty_hton_get_index_column_cardinality;
  // Safe to wire unconditionally: same Option<T> / fail-closed pattern as
  // get_table_statistics. The five string fields stay default-empty until
  // a `dd::String_type` setter reverse callback exists.
  hton->get_tablespace_statistics = rusty_hton_get_tablespace_statistics;
}

void rusty_hton_wire_encryption(handlerton *hton) {
  hton->rotate_encryption_master_key = rusty_hton_rotate_encryption_master_key;
}

void rusty_hton_wire_redo_log_set_state(handlerton *hton) {
  hton->redo_log_set_state = rusty_hton_redo_log_set_state;
}