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virtualx-engine/core/templates/command_queue_mt.h
Pedro J. Estébanez f4d76853b9 WorkerThreadPool (plus friends): Overhaul unlock allowance zones 
This fixes a rare but possible deadlock, maybe due to undefined behavior. The new implementation is safer, at the cost of some added boilerplate.
2024-08-21 12:22:52 +02:00

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/**************************************************************************/
/* command_queue_mt.h */
/**************************************************************************/
/* This file is part of: */
/* GODOT ENGINE */
/* https://godotengine.org */
/**************************************************************************/
/* Copyright (c) 2014-present Godot Engine contributors (see AUTHORS.md). */
/* Copyright (c) 2007-2014 Juan Linietsky, Ariel Manzur. */
/* */
/* Permission is hereby granted, free of charge, to any person obtaining */
/* a copy of this software and associated documentation files (the */
/* "Software"), to deal in the Software without restriction, including */
/* without limitation the rights to use, copy, modify, merge, publish, */
/* distribute, sublicense, and/or sell copies of the Software, and to */
/* permit persons to whom the Software is furnished to do so, subject to */
/* the following conditions: */
/* */
/* The above copyright notice and this permission notice shall be */
/* included in all copies or substantial portions of the Software. */
/* */
/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, */
/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF */
/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. */
/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY */
/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, */
/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE */
/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */
/**************************************************************************/
#ifndef COMMAND_QUEUE_MT_H
#define COMMAND_QUEUE_MT_H
#include "core/object/worker_thread_pool.h"
#include "core/os/condition_variable.h"
#include "core/os/memory.h"
#include "core/os/mutex.h"
#include "core/string/print_string.h"
#include "core/templates/local_vector.h"
#include "core/templates/simple_type.h"
#include "core/typedefs.h"
#define COMMA(N) _COMMA_##N
#define _COMMA_0
#define _COMMA_1 ,
#define _COMMA_2 ,
#define _COMMA_3 ,
#define _COMMA_4 ,
#define _COMMA_5 ,
#define _COMMA_6 ,
#define _COMMA_7 ,
#define _COMMA_8 ,
#define _COMMA_9 ,
#define _COMMA_10 ,
#define _COMMA_11 ,
#define _COMMA_12 ,
#define _COMMA_13 ,
#define _COMMA_14 ,
#define _COMMA_15 ,
// 1-based comma separated list of ITEMs
#define COMMA_SEP_LIST(ITEM, LENGTH) _COMMA_SEP_LIST_##LENGTH(ITEM)
#define _COMMA_SEP_LIST_15(ITEM) \
_COMMA_SEP_LIST_14(ITEM) \
, ITEM(15)
#define _COMMA_SEP_LIST_14(ITEM) \
_COMMA_SEP_LIST_13(ITEM) \
, ITEM(14)
#define _COMMA_SEP_LIST_13(ITEM) \
_COMMA_SEP_LIST_12(ITEM) \
, ITEM(13)
#define _COMMA_SEP_LIST_12(ITEM) \
_COMMA_SEP_LIST_11(ITEM) \
, ITEM(12)
#define _COMMA_SEP_LIST_11(ITEM) \
_COMMA_SEP_LIST_10(ITEM) \
, ITEM(11)
#define _COMMA_SEP_LIST_10(ITEM) \
_COMMA_SEP_LIST_9(ITEM) \
, ITEM(10)
#define _COMMA_SEP_LIST_9(ITEM) \
_COMMA_SEP_LIST_8(ITEM) \
, ITEM(9)
#define _COMMA_SEP_LIST_8(ITEM) \
_COMMA_SEP_LIST_7(ITEM) \
, ITEM(8)
#define _COMMA_SEP_LIST_7(ITEM) \
_COMMA_SEP_LIST_6(ITEM) \
, ITEM(7)
#define _COMMA_SEP_LIST_6(ITEM) \
_COMMA_SEP_LIST_5(ITEM) \
, ITEM(6)
#define _COMMA_SEP_LIST_5(ITEM) \
_COMMA_SEP_LIST_4(ITEM) \
, ITEM(5)
#define _COMMA_SEP_LIST_4(ITEM) \
_COMMA_SEP_LIST_3(ITEM) \
, ITEM(4)
#define _COMMA_SEP_LIST_3(ITEM) \
_COMMA_SEP_LIST_2(ITEM) \
, ITEM(3)
#define _COMMA_SEP_LIST_2(ITEM) \
_COMMA_SEP_LIST_1(ITEM) \
, ITEM(2)
#define _COMMA_SEP_LIST_1(ITEM) \
_COMMA_SEP_LIST_0(ITEM) \
ITEM(1)
#define _COMMA_SEP_LIST_0(ITEM)
// 1-based semicolon separated list of ITEMs
#define SEMIC_SEP_LIST(ITEM, LENGTH) _SEMIC_SEP_LIST_##LENGTH(ITEM)
#define _SEMIC_SEP_LIST_15(ITEM) \
_SEMIC_SEP_LIST_14(ITEM); \
ITEM(15)
#define _SEMIC_SEP_LIST_14(ITEM) \
_SEMIC_SEP_LIST_13(ITEM); \
ITEM(14)
#define _SEMIC_SEP_LIST_13(ITEM) \
_SEMIC_SEP_LIST_12(ITEM); \
ITEM(13)
#define _SEMIC_SEP_LIST_12(ITEM) \
_SEMIC_SEP_LIST_11(ITEM); \
ITEM(12)
#define _SEMIC_SEP_LIST_11(ITEM) \
_SEMIC_SEP_LIST_10(ITEM); \
ITEM(11)
#define _SEMIC_SEP_LIST_10(ITEM) \
_SEMIC_SEP_LIST_9(ITEM); \
ITEM(10)
#define _SEMIC_SEP_LIST_9(ITEM) \
_SEMIC_SEP_LIST_8(ITEM); \
ITEM(9)
#define _SEMIC_SEP_LIST_8(ITEM) \
_SEMIC_SEP_LIST_7(ITEM); \
ITEM(8)
#define _SEMIC_SEP_LIST_7(ITEM) \
_SEMIC_SEP_LIST_6(ITEM); \
ITEM(7)
#define _SEMIC_SEP_LIST_6(ITEM) \
_SEMIC_SEP_LIST_5(ITEM); \
ITEM(6)
#define _SEMIC_SEP_LIST_5(ITEM) \
_SEMIC_SEP_LIST_4(ITEM); \
ITEM(5)
#define _SEMIC_SEP_LIST_4(ITEM) \
_SEMIC_SEP_LIST_3(ITEM); \
ITEM(4)
#define _SEMIC_SEP_LIST_3(ITEM) \
_SEMIC_SEP_LIST_2(ITEM); \
ITEM(3)
#define _SEMIC_SEP_LIST_2(ITEM) \
_SEMIC_SEP_LIST_1(ITEM); \
ITEM(2)
#define _SEMIC_SEP_LIST_1(ITEM) \
_SEMIC_SEP_LIST_0(ITEM) \
ITEM(1)
#define _SEMIC_SEP_LIST_0(ITEM)
// 1-based space separated list of ITEMs
#define SPACE_SEP_LIST(ITEM, LENGTH) _SPACE_SEP_LIST_##LENGTH(ITEM)
#define _SPACE_SEP_LIST_15(ITEM) \
_SPACE_SEP_LIST_14(ITEM) \
ITEM(15)
#define _SPACE_SEP_LIST_14(ITEM) \
_SPACE_SEP_LIST_13(ITEM) \
ITEM(14)
#define _SPACE_SEP_LIST_13(ITEM) \
_SPACE_SEP_LIST_12(ITEM) \
ITEM(13)
#define _SPACE_SEP_LIST_12(ITEM) \
_SPACE_SEP_LIST_11(ITEM) \
ITEM(12)
#define _SPACE_SEP_LIST_11(ITEM) \
_SPACE_SEP_LIST_10(ITEM) \
ITEM(11)
#define _SPACE_SEP_LIST_10(ITEM) \
_SPACE_SEP_LIST_9(ITEM) \
ITEM(10)
#define _SPACE_SEP_LIST_9(ITEM) \
_SPACE_SEP_LIST_8(ITEM) \
ITEM(9)
#define _SPACE_SEP_LIST_8(ITEM) \
_SPACE_SEP_LIST_7(ITEM) \
ITEM(8)
#define _SPACE_SEP_LIST_7(ITEM) \
_SPACE_SEP_LIST_6(ITEM) \
ITEM(7)
#define _SPACE_SEP_LIST_6(ITEM) \
_SPACE_SEP_LIST_5(ITEM) \
ITEM(6)
#define _SPACE_SEP_LIST_5(ITEM) \
_SPACE_SEP_LIST_4(ITEM) \
ITEM(5)
#define _SPACE_SEP_LIST_4(ITEM) \
_SPACE_SEP_LIST_3(ITEM) \
ITEM(4)
#define _SPACE_SEP_LIST_3(ITEM) \
_SPACE_SEP_LIST_2(ITEM) \
ITEM(3)
#define _SPACE_SEP_LIST_2(ITEM) \
_SPACE_SEP_LIST_1(ITEM) \
ITEM(2)
#define _SPACE_SEP_LIST_1(ITEM) \
_SPACE_SEP_LIST_0(ITEM) \
ITEM(1)
#define _SPACE_SEP_LIST_0(ITEM)
#define ARG(N) p##N
#define PARAM(N) P##N p##N
#define TYPE_PARAM(N) typename P##N
#define PARAM_DECL(N) GetSimpleTypeT<P##N> p##N
#define DECL_CMD(N) \
template <typename T, typename M COMMA(N) COMMA_SEP_LIST(TYPE_PARAM, N)> \
struct Command##N : public CommandBase { \
T *instance; \
M method; \
SEMIC_SEP_LIST(PARAM_DECL, N); \
virtual void call() override { \
(instance->*method)(COMMA_SEP_LIST(ARG, N)); \
} \
};
#define DECL_CMD_RET(N) \
template <typename T, typename M, COMMA_SEP_LIST(TYPE_PARAM, N) COMMA(N) typename R> \
struct CommandRet##N : public SyncCommand { \
R *ret; \
T *instance; \
M method; \
SEMIC_SEP_LIST(PARAM_DECL, N); \
virtual void call() override { \
*ret = (instance->*method)(COMMA_SEP_LIST(ARG, N)); \
} \
};
#define DECL_CMD_SYNC(N) \
template <typename T, typename M COMMA(N) COMMA_SEP_LIST(TYPE_PARAM, N)> \
struct CommandSync##N : public SyncCommand { \
T *instance; \
M method; \
SEMIC_SEP_LIST(PARAM_DECL, N); \
virtual void call() override { \
(instance->*method)(COMMA_SEP_LIST(ARG, N)); \
} \
};
#define TYPE_ARG(N) P##N
#define CMD_TYPE(N) Command##N<T, M COMMA(N) COMMA_SEP_LIST(TYPE_ARG, N)>
#define CMD_ASSIGN_PARAM(N) cmd->p##N = p##N
#define DECL_PUSH(N) \
template <typename T, typename M COMMA(N) COMMA_SEP_LIST(TYPE_PARAM, N)> \
void push(T *p_instance, M p_method COMMA(N) COMMA_SEP_LIST(PARAM, N)) { \
MutexLock mlock(mutex); \
CMD_TYPE(N) *cmd = allocate<CMD_TYPE(N)>(); \
cmd->instance = p_instance; \
cmd->method = p_method; \
SEMIC_SEP_LIST(CMD_ASSIGN_PARAM, N); \
if (pump_task_id != WorkerThreadPool::INVALID_TASK_ID) { \
WorkerThreadPool::get_singleton()->notify_yield_over(pump_task_id); \
} \
}
#define CMD_RET_TYPE(N) CommandRet##N<T, M, COMMA_SEP_LIST(TYPE_ARG, N) COMMA(N) R>
#define DECL_PUSH_AND_RET(N) \
template <typename T, typename M, COMMA_SEP_LIST(TYPE_PARAM, N) COMMA(N) typename R> \
void push_and_ret(T *p_instance, M p_method, COMMA_SEP_LIST(PARAM, N) COMMA(N) R *r_ret) { \
MutexLock mlock(mutex); \
CMD_RET_TYPE(N) *cmd = allocate<CMD_RET_TYPE(N)>(); \
cmd->instance = p_instance; \
cmd->method = p_method; \
SEMIC_SEP_LIST(CMD_ASSIGN_PARAM, N); \
cmd->ret = r_ret; \
if (pump_task_id != WorkerThreadPool::INVALID_TASK_ID) { \
WorkerThreadPool::get_singleton()->notify_yield_over(pump_task_id); \
} \
sync_tail++; \
_wait_for_sync(mlock); \
}
#define CMD_SYNC_TYPE(N) CommandSync##N<T, M COMMA(N) COMMA_SEP_LIST(TYPE_ARG, N)>
#define DECL_PUSH_AND_SYNC(N) \
template <typename T, typename M COMMA(N) COMMA_SEP_LIST(TYPE_PARAM, N)> \
void push_and_sync(T *p_instance, M p_method COMMA(N) COMMA_SEP_LIST(PARAM, N)) { \
MutexLock mlock(mutex); \
CMD_SYNC_TYPE(N) *cmd = allocate<CMD_SYNC_TYPE(N)>(); \
cmd->instance = p_instance; \
cmd->method = p_method; \
SEMIC_SEP_LIST(CMD_ASSIGN_PARAM, N); \
if (pump_task_id != WorkerThreadPool::INVALID_TASK_ID) { \
WorkerThreadPool::get_singleton()->notify_yield_over(pump_task_id); \
} \
sync_tail++; \
_wait_for_sync(mlock); \
}
#define MAX_CMD_PARAMS 15
class CommandQueueMT {
struct CommandBase {
bool sync = false;
virtual void call() = 0;
virtual ~CommandBase() = default;
};
struct SyncCommand : public CommandBase {
virtual void call() override {}
SyncCommand() {
sync = true;
}
};
DECL_CMD(0)
SPACE_SEP_LIST(DECL_CMD, 15)
// Commands that return.
DECL_CMD_RET(0)
SPACE_SEP_LIST(DECL_CMD_RET, 15)
/* commands that don't return but sync */
DECL_CMD_SYNC(0)
SPACE_SEP_LIST(DECL_CMD_SYNC, 15)
/***** BASE *******/
static const uint32_t DEFAULT_COMMAND_MEM_SIZE_KB = 64;
BinaryMutex mutex;
LocalVector<uint8_t> command_mem;
ConditionVariable sync_cond_var;
uint32_t sync_head = 0;
uint32_t sync_tail = 0;
uint32_t sync_awaiters = 0;
WorkerThreadPool::TaskID pump_task_id = WorkerThreadPool::INVALID_TASK_ID;
uint64_t flush_read_ptr = 0;
template <typename T>
T *allocate() {
// alloc size is size+T+safeguard
uint32_t alloc_size = ((sizeof(T) + 8 - 1) & ~(8 - 1));
uint64_t size = command_mem.size();
command_mem.resize(size + alloc_size + 8);
*(uint64_t *)&command_mem[size] = alloc_size;
T *cmd = memnew_placement(&command_mem[size + 8], T);
return cmd;
}
_FORCE_INLINE_ void _prevent_sync_wraparound() {
bool safe_to_reset = !sync_awaiters;
bool already_sync_to_latest = sync_head == sync_tail;
if (safe_to_reset && already_sync_to_latest) {
sync_head = 0;
sync_tail = 0;
}
}
void _flush() {
if (unlikely(flush_read_ptr)) {
// Re-entrant call.
return;
}
MutexLock lock(mutex);
while (flush_read_ptr < command_mem.size()) {
uint64_t size = *(uint64_t *)&command_mem[flush_read_ptr];
flush_read_ptr += 8;
CommandBase *cmd = reinterpret_cast<CommandBase *>(&command_mem[flush_read_ptr]);
uint32_t allowance_id = WorkerThreadPool::thread_enter_unlock_allowance_zone(lock);
cmd->call();
WorkerThreadPool::thread_exit_unlock_allowance_zone(allowance_id);
// Handle potential realloc due to the command and unlock allowance.
cmd = reinterpret_cast<CommandBase *>(&command_mem[flush_read_ptr]);
if (unlikely(cmd->sync)) {
sync_head++;
lock.~MutexLock(); // Give an opportunity to awaiters right away.
sync_cond_var.notify_all();
new (&lock) MutexLock(mutex);
// Handle potential realloc happened during unlock.
cmd = reinterpret_cast<CommandBase *>(&command_mem[flush_read_ptr]);
}
cmd->~CommandBase();
flush_read_ptr += size;
}
command_mem.clear();
flush_read_ptr = 0;
_prevent_sync_wraparound();
}
_FORCE_INLINE_ void _wait_for_sync(MutexLock<BinaryMutex> &p_lock) {
sync_awaiters++;
uint32_t sync_head_goal = sync_tail;
do {
sync_cond_var.wait(p_lock);
} while (sync_head < sync_head_goal);
sync_awaiters--;
_prevent_sync_wraparound();
}
void _no_op() {}
public:
/* NORMAL PUSH COMMANDS */
DECL_PUSH(0)
SPACE_SEP_LIST(DECL_PUSH, 15)
/* PUSH AND RET COMMANDS */
DECL_PUSH_AND_RET(0)
SPACE_SEP_LIST(DECL_PUSH_AND_RET, 15)
/* PUSH AND RET SYNC COMMANDS*/
DECL_PUSH_AND_SYNC(0)
SPACE_SEP_LIST(DECL_PUSH_AND_SYNC, 15)
_FORCE_INLINE_ void flush_if_pending() {
if (unlikely(command_mem.size() > 0)) {
_flush();
}
}
void flush_all() {
_flush();
}
void sync() {
push_and_sync(this, &CommandQueueMT::_no_op);
}
void wait_and_flush() {
ERR_FAIL_COND(pump_task_id == WorkerThreadPool::INVALID_TASK_ID);
WorkerThreadPool::get_singleton()->wait_for_task_completion(pump_task_id);
_flush();
}
void set_pump_task_id(WorkerThreadPool::TaskID p_task_id) {
MutexLock lock(mutex);
pump_task_id = p_task_id;
}
CommandQueueMT();
~CommandQueueMT();
};
#undef ARG
#undef PARAM
#undef TYPE_PARAM
#undef PARAM_DECL
#undef DECL_CMD
#undef DECL_CMD_RET
#undef DECL_CMD_SYNC
#undef TYPE_ARG
#undef CMD_TYPE
#undef CMD_ASSIGN_PARAM
#undef DECL_PUSH
#undef CMD_RET_TYPE
#undef DECL_PUSH_AND_RET
#undef CMD_SYNC_TYPE
#undef DECL_CMD_SYNC
#endif // COMMAND_QUEUE_MT_H
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