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godot/core/command_queue_mt.h
Hein-Pieter van Braam 24e7a54cd0 Fix alignment and locking issues with CommandQueueMT 
The allocations of commands in CommandQueueMT weren't aligned. This
commit aligns all accesses on 64bit boundaries regardless of target
platform. This ensures that all types are aligned.

Lock-wise the semaphores were maked as usable when the command had ran
but not when the synchronous stub had finished with it. This lead to a
race condition where sometimes the semaphore got reused before it was
waited on. We now mark the semaphore as free only once we're done
waiting on it.
2019-02-16 04:00:19 +01:00

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/*************************************************************************/
/* command_queue_mt.h */
/*************************************************************************/
/* This file is part of: */
/* GODOT ENGINE */
/* https://godotengine.org */
/*************************************************************************/
/* Copyright (c) 2007-2019 Juan Linietsky, Ariel Manzur. */
/* Copyright (c) 2014-2019 Godot Engine contributors (cf. AUTHORS.md) */
/* */
/* 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/os/memory.h"
#include "core/os/mutex.h"
#include "core/os/semaphore.h"
#include "core/simple_type.h"
#include "core/typedefs.h"
/**
@author Juan Linietsky <reduzio@gmail.com>
*/
#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 ,
// 1-based comma separated list of ITEMs
#define COMMA_SEP_LIST(ITEM, LENGTH) _COMMA_SEP_LIST_##LENGTH(ITEM)
#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_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_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) class P##N
#define PARAM_DECL(N) typename GetSimpleTypeT<P##N>::type_t p##N
#define DECL_CMD(N) \
template <class T, class 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() { \
(instance->*method)(COMMA_SEP_LIST(ARG, N)); \
} \
};
#define DECL_CMD_RET(N) \
template <class T, class M, COMMA_SEP_LIST(TYPE_PARAM, N) COMMA(N) class R> \
struct CommandRet##N : public SyncCommand { \
R *ret; \
T *instance; \
M method; \
SEMIC_SEP_LIST(PARAM_DECL, N); \
virtual void call() { \
*ret = (instance->*method)(COMMA_SEP_LIST(ARG, N)); \
} \
};
#define DECL_CMD_SYNC(N) \
template <class T, class 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() { \
(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 <class T, class M COMMA(N) COMMA_SEP_LIST(TYPE_PARAM, N)> \
void push(T *p_instance, M p_method COMMA(N) COMMA_SEP_LIST(PARAM, N)) { \
CMD_TYPE(N) *cmd = allocate_and_lock<CMD_TYPE(N)>(); \
cmd->instance = p_instance; \
cmd->method = p_method; \
SEMIC_SEP_LIST(CMD_ASSIGN_PARAM, N); \
unlock(); \
if (sync) sync->post(); \
}
#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 <class T, class M, COMMA_SEP_LIST(TYPE_PARAM, N) COMMA(N) class R> \
void push_and_ret(T *p_instance, M p_method, COMMA_SEP_LIST(PARAM, N) COMMA(N) R *r_ret) { \
SyncSemaphore *ss = _alloc_sync_sem(); \
CMD_RET_TYPE(N) *cmd = allocate_and_lock<CMD_RET_TYPE(N)>(); \
cmd->instance = p_instance; \
cmd->method = p_method; \
SEMIC_SEP_LIST(CMD_ASSIGN_PARAM, N); \
cmd->ret = r_ret; \
cmd->sync_sem = ss; \
unlock(); \
if (sync) sync->post(); \
ss->sem->wait(); \
ss->in_use = false; \
}
#define CMD_SYNC_TYPE(N) CommandSync##N<T, M COMMA(N) COMMA_SEP_LIST(TYPE_ARG, N)>
#define DECL_PUSH_AND_SYNC(N) \
template <class T, class 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)) { \
SyncSemaphore *ss = _alloc_sync_sem(); \
CMD_SYNC_TYPE(N) *cmd = allocate_and_lock<CMD_SYNC_TYPE(N)>(); \
cmd->instance = p_instance; \
cmd->method = p_method; \
SEMIC_SEP_LIST(CMD_ASSIGN_PARAM, N); \
cmd->sync_sem = ss; \
unlock(); \
if (sync) sync->post(); \
ss->sem->wait(); \
ss->in_use = false; \
}
#define MAX_CMD_PARAMS 13
class CommandQueueMT {
struct SyncSemaphore {
Semaphore *sem;
bool in_use;
};
struct CommandBase {
virtual void call() = 0;
virtual void post(){};
virtual ~CommandBase(){};
};
struct SyncCommand : public CommandBase {
SyncSemaphore *sync_sem;
virtual void post() {
sync_sem->sem->post();
}
};
DECL_CMD(0)
SPACE_SEP_LIST(DECL_CMD, 13)
/* comands that return */
DECL_CMD_RET(0)
SPACE_SEP_LIST(DECL_CMD_RET, 13)
/* commands that don't return but sync */
DECL_CMD_SYNC(0)
SPACE_SEP_LIST(DECL_CMD_SYNC, 13)
/***** BASE *******/
enum {
COMMAND_MEM_SIZE_KB = 256,
COMMAND_MEM_SIZE = COMMAND_MEM_SIZE_KB * 1024,
SYNC_SEMAPHORES = 8
};
uint8_t *command_mem;
uint32_t read_ptr;
uint32_t write_ptr;
uint32_t dealloc_ptr;
SyncSemaphore sync_sems[SYNC_SEMAPHORES];
Mutex *mutex;
Semaphore *sync;
template <class T>
T *allocate() {
// alloc size is size+T+safeguard
uint32_t alloc_size = ((sizeof(T) + 8 - 1) & ~(8 - 1)) + 8;
tryagain:
if (write_ptr < dealloc_ptr) {
// behind dealloc_ptr, check that there is room
if ((dealloc_ptr - write_ptr) <= alloc_size) {
// There is no more room, try to deallocate something
if (dealloc_one()) {
goto tryagain;
}
return NULL;
}
} else if (write_ptr >= dealloc_ptr) {
// ahead of dealloc_ptr, check that there is room
if ((COMMAND_MEM_SIZE - write_ptr) < alloc_size + sizeof(uint32_t)) {
// no room at the end, wrap down;
if (dealloc_ptr == 0) { // don't want write_ptr to become dealloc_ptr
// There is no more room, try to deallocate something
if (dealloc_one()) {
goto tryagain;
}
return NULL;
}
// if this happens, it's a bug
ERR_FAIL_COND_V((COMMAND_MEM_SIZE - write_ptr) < 8, NULL);
// zero means, wrap to beginning
uint32_t *p = (uint32_t *)&command_mem[write_ptr];
*p = 0;
write_ptr = 0;
goto tryagain;
}
}
// Allocate the size and the 'in use' bit.
// First bit used to mark if command is still in use (1)
// or if it has been destroyed and can be deallocated (0).
uint32_t size = (sizeof(T) + 8 - 1) & ~(8 - 1);
uint32_t *p = (uint32_t *)&command_mem[write_ptr];
*p = (size << 1) | 1;
write_ptr += 8;
// allocate the command
T *cmd = memnew_placement(&command_mem[write_ptr], T);
write_ptr += size;
return cmd;
}
template <class T>
T *allocate_and_lock() {
lock();
T *ret;
while ((ret = allocate<T>()) == NULL) {
unlock();
// sleep a little until fetch happened and some room is made
wait_for_flush();
lock();
}
return ret;
}
bool flush_one(bool p_lock = true) {
if (p_lock) lock();
tryagain:
// tried to read an empty queue
if (read_ptr == write_ptr)
return false;
uint32_t size_ptr = read_ptr;
uint32_t size = *(uint32_t *)&command_mem[read_ptr] >> 1;
if (size == 0) {
//end of ringbuffer, wrap
read_ptr = 0;
goto tryagain;
}
read_ptr += 8;
CommandBase *cmd = reinterpret_cast<CommandBase *>(&command_mem[read_ptr]);
read_ptr += size;
if (p_lock) unlock();
cmd->call();
if (p_lock) lock();
cmd->post();
cmd->~CommandBase();
*(uint32_t *)&command_mem[size_ptr] &= ~1;
if (p_lock) unlock();
return true;
}
void lock();
void unlock();
void wait_for_flush();
SyncSemaphore *_alloc_sync_sem();
bool dealloc_one();
public:
/* NORMAL PUSH COMMANDS */
DECL_PUSH(0)
SPACE_SEP_LIST(DECL_PUSH, 13)
/* PUSH AND RET COMMANDS */
DECL_PUSH_AND_RET(0)
SPACE_SEP_LIST(DECL_PUSH_AND_RET, 13)
/* PUSH AND RET SYNC COMMANDS*/
DECL_PUSH_AND_SYNC(0)
SPACE_SEP_LIST(DECL_PUSH_AND_SYNC, 13)
void wait_and_flush_one() {
ERR_FAIL_COND(!sync);
sync->wait();
flush_one();
}
void flush_all() {
//ERR_FAIL_COND(sync);
lock();
while (flush_one(false))
;
unlock();
}
CommandQueueMT(bool p_sync);
~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
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