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Codechange: Template the command callback function type to allow unpacked arguments.

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This commit is contained in:
Michael Lutz
2021-11-28 17:37:04 +01:00
parent 13528bfcd0
commit d85348b1d1
7 changed files with 153 additions and 71 deletions
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2
src/network/network_client.cpp
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@@ -840,7 +840,7 @@ NetworkRecvStatus ClientNetworkGameSocketHandler::Receive_SERVER_MAP_DONE(Packet
* the server will give us a client-id and let us in */
_network_join_status = NETWORK_JOIN_STATUS_REGISTERING;
ShowJoinStatusWindow();
Command<CMD_COMPANY_CTRL>::SendNet(STR_NULL, nullptr, _local_company, CCA_NEW, INVALID_COMPANY, CRR_NONE, INVALID_CLIENT_ID);
Command<CMD_COMPANY_CTRL>::SendNet(STR_NULL, _local_company, CCA_NEW, INVALID_COMPANY, CRR_NONE, INVALID_CLIENT_ID);
}
} else {
/* take control over an existing company */

156
src/network/network_command.cpp
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@@ -53,55 +53,95 @@
#include "../safeguards.h"
/** Table with all the callbacks we'll use for conversion*/
static CommandCallback * const _callback_table[] = {
/* 0x00 */ nullptr,
/* 0x01 */ CcBuildPrimaryVehicle,
/* 0x02 */ CcBuildAirport,
/* 0x03 */ CcBuildBridge,
/* 0x04 */ CcPlaySound_CONSTRUCTION_WATER,
/* 0x05 */ CcBuildDocks,
/* 0x06 */ CcFoundTown,
/* 0x07 */ CcBuildRoadTunnel,
/* 0x08 */ CcBuildRailTunnel,
/* 0x09 */ CcBuildWagon,
/* 0x0A */ CcRoadDepot,
/* 0x0B */ CcRailDepot,
/* 0x0C */ CcPlaceSign,
/* 0x0D */ CcPlaySound_EXPLOSION,
/* 0x0E */ CcPlaySound_CONSTRUCTION_OTHER,
/* 0x0F */ CcPlaySound_CONSTRUCTION_RAIL,
/* 0x10 */ CcStation,
/* 0x11 */ CcTerraform,
/* 0x12 */ CcAI,
/* 0x13 */ CcCloneVehicle,
/* 0x14 */ nullptr,
/* 0x15 */ CcCreateGroup,
/* 0x16 */ CcFoundRandomTown,
/* 0x17 */ CcRoadStop,
/* 0x18 */ CcBuildIndustry,
/* 0x19 */ CcStartStopVehicle,
/* 0x1A */ CcGame,
/* 0x1B */ CcAddVehicleNewGroup,
};
/** Typed list of all possible callbacks. */
static constexpr auto _callback_tuple = std::make_tuple(
(CommandCallback *)nullptr, // Make sure this is actually a pointer-to-function.
&CcBuildPrimaryVehicle,
&CcBuildAirport,
&CcBuildBridge,
&CcPlaySound_CONSTRUCTION_WATER,
&CcBuildDocks,
&CcFoundTown,
&CcBuildRoadTunnel,
&CcBuildRailTunnel,
&CcBuildWagon,
&CcRoadDepot,
&CcRailDepot,
&CcPlaceSign,
&CcPlaySound_EXPLOSION,
&CcPlaySound_CONSTRUCTION_OTHER,
&CcPlaySound_CONSTRUCTION_RAIL,
&CcStation,
&CcTerraform,
&CcAI,
&CcCloneVehicle,
&CcCreateGroup,
&CcFoundRandomTown,
&CcRoadStop,
&CcBuildIndustry,
&CcStartStopVehicle,
&CcGame,
&CcAddVehicleNewGroup
);
#ifdef SILENCE_GCC_FUNCTION_POINTER_CAST
/*
* We cast specialized function pointers to a generic one, but don't use the
* converted value to call the function, which is safe, except that GCC
* helpfully thinks it is not.
*
* "Any pointer to function can be converted to a pointer to a different function type.
* Calling the function through a pointer to a different function type is undefined,
* but converting such pointer back to pointer to the original function type yields
* the pointer to the original function." */
# pragma GCC diagnostic push
# pragma GCC diagnostic ignored "-Wcast-function-type"
#endif
/* Helpers to generate the callback table from the callback list. */
inline constexpr size_t _callback_tuple_size = std::tuple_size_v<decltype(_callback_tuple)>;
template <size_t... i>
inline auto MakeCallbackTable(std::index_sequence<i...>) noexcept
{
return std::array<CommandCallback *, sizeof...(i)>{{ reinterpret_cast<CommandCallback *>(reinterpret_cast<void(*)()>(std::get<i>(_callback_tuple)))... }}; // MingW64 fails linking when casting a pointer to its own type. To work around, cast it to some other type first.
}
/** Type-erased table of callbacks. */
static auto _callback_table = MakeCallbackTable(std::make_index_sequence<_callback_tuple_size>{});
/* Helpers to generate the command dispatch table from the command traits. */
template <Commands Tcmd> static CommandDataBuffer SanitizeCmdStrings(const CommandDataBuffer &data);
template <Commands Tcmd> static void UnpackNetworkCommand(const CommandPacket *cp);
template <Commands Tcmd, size_t cb> static void UnpackNetworkCommand(const CommandPacket *cp);
template <Commands Tcmd> static void NetworkReplaceCommandClientId(CommandPacket &cp, ClientID client_id);
using UnpackNetworkCommandProc = void (*)(const CommandPacket *);
using UnpackDispatchT = std::array<UnpackNetworkCommandProc, _callback_tuple_size>;
struct CommandDispatch {
CommandDataBuffer(*Sanitize)(const CommandDataBuffer &);
void (*ReplaceClientId)(CommandPacket &, ClientID);
void (*Unpack)(const CommandPacket *);
UnpackDispatchT Unpack;
};
template<typename T, T... i>
inline constexpr auto MakeDispatchTable(std::integer_sequence<T, i...>) noexcept
template <Commands Tcmd, size_t... i>
constexpr UnpackDispatchT MakeUnpackNetworkCommand(std::index_sequence<i...>) noexcept
{
return std::array<CommandDispatch, sizeof...(i)>{{ { &SanitizeCmdStrings<static_cast<Commands>(i)>, &NetworkReplaceCommandClientId<static_cast<Commands>(i)>, &UnpackNetworkCommand<static_cast<Commands>(i)> }... }};
return UnpackDispatchT{{ {&UnpackNetworkCommand<Tcmd, i>}... }};
}
static constexpr auto _cmd_dispatch = MakeDispatchTable(std::make_integer_sequence<std::underlying_type_t<Commands>, CMD_END>{});
template <typename T, T... i, size_t... j>
inline constexpr auto MakeDispatchTable(std::integer_sequence<T, i...>, std::index_sequence<j...>) noexcept
{
return std::array<CommandDispatch, sizeof...(i)>{{ { &SanitizeCmdStrings<static_cast<Commands>(i)>, &NetworkReplaceCommandClientId<static_cast<Commands>(i)>, MakeUnpackNetworkCommand<static_cast<Commands>(i)>(std::make_index_sequence<_callback_tuple_size>{}) }... }};
}
/** Command dispatch table. */
static constexpr auto _cmd_dispatch = MakeDispatchTable(std::make_integer_sequence<std::underlying_type_t<Commands>, CMD_END>{}, std::make_index_sequence<_callback_tuple_size>{});
#ifdef SILENCE_GCC_FUNCTION_POINTER_CAST
# pragma GCC diagnostic pop
#endif
/**
@@ -179,6 +219,20 @@ static CommandQueue _local_wait_queue;
static CommandQueue _local_execution_queue;
/**
* Find the callback index of a callback pointer.
* @param callback Address of callback to search for.
* @return Callback index or std::numeric_limits<size_t>::max() if the function wasn't found in the callback list.
*/
static size_t FindCallbackIndex(CommandCallback *callback)
{
if (auto it = std::find(std::cbegin(_callback_table), std::cend(_callback_table), callback); it != std::cend(_callback_table)) {
return static_cast<size_t>(std::distance(std::cbegin(_callback_table), it));
}
return std::numeric_limits<size_t>::max();
}
/**
* Prepare a DoCommand to be send over the network
* @param cmd The command to execute (a CMD_* value)
@@ -259,7 +313,9 @@ void NetworkExecuteLocalCommandQueue()
/* We can execute this command */
_current_company = cp->company;
_cmd_dispatch[cp->cmd].Unpack(cp);
size_t cb_index = FindCallbackIndex(cp->callback);
assert(cb_index < _callback_tuple_size);
_cmd_dispatch[cp->cmd].Unpack[cb_index](cp);
queue.Pop();
delete cp;
@@ -354,7 +410,7 @@ const char *NetworkGameSocketHandler::ReceiveCommand(Packet *p, CommandPacket *c
cp->data = _cmd_dispatch[cp->cmd].Sanitize(p->Recv_buffer());
byte callback = p->Recv_uint8();
if (callback >= lengthof(_callback_table)) return "invalid callback";
if (callback >= _callback_table.size()) return "invalid callback";
cp->callback = _callback_table[callback];
return nullptr;
@@ -373,16 +429,12 @@ void NetworkGameSocketHandler::SendCommand(Packet *p, const CommandPacket *cp)
p->Send_uint32(cp->tile);
p->Send_buffer(cp->data);
byte callback = 0;
while (callback < lengthof(_callback_table) && _callback_table[callback] != cp->callback) {
callback++;
}
if (callback == lengthof(_callback_table)) {
size_t callback = FindCallbackIndex(cp->callback);
if (callback > UINT8_MAX) {
Debug(net, 0, "Unknown callback for command; no callback sent (command: {})", cp->cmd);
callback = 0; // _callback_table[0] == nullptr
}
p->Send_uint8 (callback);
p->Send_uint8 ((uint8)callback);
}
/** Helper to process a single ClientID argument. */
@@ -455,9 +507,15 @@ CommandDataBuffer SanitizeCmdStrings(const CommandDataBuffer &data)
return EndianBufferWriter<CommandDataBuffer>::FromValue(args);
}
template <Commands Tcmd>
void UnpackNetworkCommand(const CommandPacket *cp)
/**
* Unpack a generic command packet into its actual typed components.
* @tparam Tcmd Command type to be unpacked.
* @tparam Tcb Index into the callback list.
* @param cp Command packet to unpack.
*/
template <Commands Tcmd, size_t Tcb>
void UnpackNetworkCommand(const CommandPacket* cp)
{
auto args = EndianBufferReader::ToValue<typename CommandTraits<Tcmd>::Args>(cp->data);
Command<Tcmd>::PostFromNet(cp->err_msg, cp->callback, cp->my_cmd, cp->tile, args);
Command<Tcmd>::PostFromNet(cp->err_msg, std::get<Tcb>(_callback_tuple), cp->my_cmd, cp->tile, args);
}

2
src/network/network_gui.cpp
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@@ -1538,7 +1538,7 @@ private:
if (_network_server) {
Command<CMD_COMPANY_CTRL>::Post(CCA_NEW, INVALID_COMPANY, CRR_NONE, _network_own_client_id);
} else {
Command<CMD_COMPANY_CTRL>::SendNet(STR_NULL, nullptr, _local_company, CCA_NEW, INVALID_COMPANY, CRR_NONE, INVALID_CLIENT_ID);
Command<CMD_COMPANY_CTRL>::SendNet(STR_NULL, _local_company, CCA_NEW, INVALID_COMPANY, CRR_NONE, INVALID_CLIENT_ID);
}
}

2
src/network/network_server.cpp
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@@ -2081,7 +2081,7 @@ void NetworkServerNewCompany(const Company *c, NetworkClientInfo *ci)
/* ci is nullptr when replaying, or for AIs. In neither case there is a client. */
ci->client_playas = c->index;
NetworkUpdateClientInfo(ci->client_id);
Command<CMD_RENAME_PRESIDENT>::SendNet(STR_NULL, nullptr, c->index, ci->client_name);
Command<CMD_RENAME_PRESIDENT>::SendNet(STR_NULL, c->index, ci->client_name);
}
/* Announce new company on network. */