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/*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* 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, write to the Free Software Foundation,
* Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
/** \file
* \ingroup bli
*
* Task pool to run tasks in parallel.
*/
#include <cstdlib>
#include <memory>
#include <utility>
#include "MEM_guardedalloc.h"
#include "DNA_listBase.h"
#include "BLI_math.h"
#include "BLI_mempool.h"
#include "BLI_task.h"
#include "BLI_threads.h"
#ifdef WITH_TBB
/* Quiet top level deprecation message, unrelated to API usage here. */
# define TBB_SUPPRESS_DEPRECATED_MESSAGES 1
# include <tbb/tbb.h>
#endif
/* Task
*
* Unit of work to execute. This is a C++ class to work with TBB. */
class Task {
public:
TaskPool *pool;
TaskRunFunction run;
void *taskdata;
bool free_taskdata;
TaskFreeFunction freedata;
Task(TaskPool *pool,
TaskRunFunction run,
void *taskdata,
bool free_taskdata,
TaskFreeFunction freedata)
: pool(pool), run(run), taskdata(taskdata), free_taskdata(free_taskdata), freedata(freedata)
{
}
~Task()
{
if (free_taskdata) {
if (freedata) {
freedata(pool, taskdata);
}
else {
MEM_freeN(taskdata);
}
}
}
/* Move constructor.
* For performance, ensure we never copy the task and only move it.
* For TBB version 2017 and earlier we apply a workaround to make up for
* the lack of move constructor support. */
Task(Task &&other)
: pool(other.pool),
run(other.run),
taskdata(other.taskdata),
free_taskdata(other.free_taskdata),
freedata(other.freedata)
{
other.pool = nullptr;
other.run = nullptr;
other.taskdata = nullptr;
other.free_taskdata = false;
other.freedata = nullptr;
}
#if (defined(WITH_TBB) && TBB_INTERFACE_VERSION_MAJOR < 10) || \
(defined(__clang__) && defined(WIN32))
Task(const Task &other)
: pool(other.pool),
run(other.run),
taskdata(other.taskdata),
free_taskdata(other.free_taskdata),
freedata(other.freedata)
{
((Task &)other).pool = NULL;
((Task &)other).run = NULL;
((Task &)other).taskdata = NULL;
((Task &)other).free_taskdata = false;
((Task &)other).freedata = NULL;
}
#else
Task(const Task &other) = delete;
#endif
Task &operator=(const Task &other) = delete;
Task &operator=(Task &&other) = delete;
/* Execute task. */
void operator()() const
{
#ifdef WITH_TBB
tbb::this_task_arena::isolate([this] { run(pool, taskdata); });
#else
run(pool, taskdata);
#endif
}
};
/* TBB Task Group.
*
* Subclass since there seems to be no other way to set priority. */
#ifdef WITH_TBB
class TBBTaskGroup : public tbb::task_group {
public:
TBBTaskGroup(TaskPriority priority)
{
switch (priority) {
case TASK_PRIORITY_LOW:
my_context.set_priority(tbb::priority_low);
break;
case TASK_PRIORITY_HIGH:
my_context.set_priority(tbb::priority_normal);
break;
}
}
~TBBTaskGroup()
{
}
};
#endif
/* Task Pool */
typedef enum TaskPoolType {
TASK_POOL_TBB,
TASK_POOL_TBB_SUSPENDED,
TASK_POOL_NO_THREADS,
TASK_POOL_BACKGROUND,
TASK_POOL_BACKGROUND_SERIAL,
} TaskPoolType;
struct TaskPool {
TaskPoolType type;
bool use_threads;
ThreadMutex user_mutex;
void *userdata;
/* TBB task pool. */
#ifdef WITH_TBB
TBBTaskGroup tbb_group;
#endif
volatile bool is_suspended;
BLI_mempool *suspended_mempool;
/* Background task pool. */
ListBase background_threads;
ThreadQueue *background_queue;
volatile bool background_is_canceling;
};
/* TBB Task Pool.
*
* Task pool using the TBB scheduler for tasks. When building without TBB
* support or running Blender with -t 1, this reverts to single threaded.
*
* Tasks may be suspended until in all are created, to make it possible to
* initialize data structures and create tasks in a single pass. */
static void tbb_task_pool_create(TaskPool *pool, TaskPriority priority)
{
if (pool->type == TASK_POOL_TBB_SUSPENDED) {
pool->is_suspended = true;
pool->suspended_mempool = BLI_mempool_create(sizeof(Task), 512, 512, BLI_MEMPOOL_ALLOW_ITER);
}
#ifdef WITH_TBB
if (pool->use_threads) {
new (&pool->tbb_group) TBBTaskGroup(priority);
}
#else
UNUSED_VARS(priority);
#endif
}
static void tbb_task_pool_run(TaskPool *pool, Task &&task)
{
if (pool->is_suspended) {
/* Suspended task that will be executed in work_and_wait(). */
Task *task_mem = (Task *)BLI_mempool_alloc(pool->suspended_mempool);
new (task_mem) Task(std::move(task));
#ifdef __GNUC__
/* Work around apparent compiler bug where task is not properly copied
* to task_mem. This appears unrelated to the use of placement new or
* move semantics, happens even writing to a plain C struct. Rather the
* call into TBB seems to have some indirect effect. */
std::atomic_thread_fence(std::memory_order_release);
#endif
}
#ifdef WITH_TBB
else if (pool->use_threads) {
/* Execute in TBB task group. */
pool->tbb_group.run(std::move(task));
}
#endif
else {
/* Execute immediately. */
task();
}
}
static void tbb_task_pool_work_and_wait(TaskPool *pool)
{
/* Start any suspended task now. */
if (pool->suspended_mempool) {
pool->is_suspended = false;
BLI_mempool_iter iter;
BLI_mempool_iternew(pool->suspended_mempool, &iter);
while (Task *task = (Task *)BLI_mempool_iterstep(&iter)) {
tbb_task_pool_run(pool, std::move(*task));
}
BLI_mempool_clear(pool->suspended_mempool);
}
#ifdef WITH_TBB
if (pool->use_threads) {
/* This is called wait(), but internally it can actually do work. This
* matters because we don't want recursive usage of task pools to run
* out of threads and get stuck. */
pool->tbb_group.wait();
}
#endif
}
static void tbb_task_pool_cancel(TaskPool *pool)
{
#ifdef WITH_TBB
if (pool->use_threads) {
pool->tbb_group.cancel();
pool->tbb_group.wait();
}
#else
UNUSED_VARS(pool);
#endif
}
static bool tbb_task_pool_canceled(TaskPool *pool)
{
#ifdef WITH_TBB
if (pool->use_threads) {
return pool->tbb_group.is_canceling();
}
#else
UNUSED_VARS(pool);
#endif
return false;
}
static void tbb_task_pool_free(TaskPool *pool)
{
#ifdef WITH_TBB
if (pool->use_threads) {
pool->tbb_group.~TBBTaskGroup();
}
#endif
if (pool->suspended_mempool) {
BLI_mempool_destroy(pool->suspended_mempool);
}
}
/* Background Task Pool.
*
* Fallback for running background tasks when building without TBB. */
static void *background_task_run(void *userdata)
{
TaskPool *pool = (TaskPool *)userdata;
while (Task *task = (Task *)BLI_thread_queue_pop(pool->background_queue)) {
(*task)();
task->~Task();
MEM_freeN(task);
}
return nullptr;
}
static void background_task_pool_create(TaskPool *pool)
{
pool->background_queue = BLI_thread_queue_init();
BLI_threadpool_init(&pool->background_threads, background_task_run, 1);
}
static void background_task_pool_run(TaskPool *pool, Task &&task)
{
Task *task_mem = (Task *)MEM_mallocN(sizeof(Task), __func__);
new (task_mem) Task(std::move(task));
BLI_thread_queue_push(pool->background_queue, task_mem);
if (BLI_available_threads(&pool->background_threads)) {
BLI_threadpool_insert(&pool->background_threads, pool);
}
}
static void background_task_pool_work_and_wait(TaskPool *pool)
{
/* Signal background thread to stop waiting for new tasks if none are
* left, and wait for tasks and thread to finish. */
BLI_thread_queue_nowait(pool->background_queue);
BLI_thread_queue_wait_finish(pool->background_queue);
BLI_threadpool_clear(&pool->background_threads);
}
static void background_task_pool_cancel(TaskPool *pool)
{
pool->background_is_canceling = true;
/* Remove tasks not yet started by background thread. */
BLI_thread_queue_nowait(pool->background_queue);
while (Task *task = (Task *)BLI_thread_queue_pop(pool->background_queue)) {
task->~Task();
MEM_freeN(task);
}
/* Let background thread finish or cancel task it is working on. */
BLI_threadpool_remove(&pool->background_threads, pool);
pool->background_is_canceling = false;
}
static bool background_task_pool_canceled(TaskPool *pool)
{
return pool->background_is_canceling;
}
static void background_task_pool_free(TaskPool *pool)
{
background_task_pool_work_and_wait(pool);
BLI_threadpool_end(&pool->background_threads);
BLI_thread_queue_free(pool->background_queue);
}
/* Task Pool */
static TaskPool *task_pool_create_ex(void *userdata, TaskPoolType type, TaskPriority priority)
{
const bool use_threads = BLI_task_scheduler_num_threads() > 1 && type != TASK_POOL_NO_THREADS;
/* Background task pool uses regular TBB scheduling if available. Only when
* building without TBB or running with -t 1 do we need to ensure these tasks
* do not block the main thread. */
if (type == TASK_POOL_BACKGROUND && use_threads) {
type = TASK_POOL_TBB;
}
/* Allocate task pool. */
TaskPool *pool = (TaskPool *)MEM_callocN(sizeof(TaskPool), "TaskPool");
pool->type = type;
pool->use_threads = use_threads;
pool->userdata = userdata;
BLI_mutex_init(&pool->user_mutex);
switch (type) {
case TASK_POOL_TBB:
case TASK_POOL_TBB_SUSPENDED:
case TASK_POOL_NO_THREADS:
tbb_task_pool_create(pool, priority);
break;
case TASK_POOL_BACKGROUND:
case TASK_POOL_BACKGROUND_SERIAL:
background_task_pool_create(pool);
break;
}
return pool;
}
/**
* Create a normal task pool. Tasks will be executed as soon as they are added.
*/
TaskPool *BLI_task_pool_create(void *userdata, TaskPriority priority)
{
return task_pool_create_ex(userdata, TASK_POOL_TBB, priority);
}
/**
* Create a background task pool.
* In multi-threaded context, there is no differences with #BLI_task_pool_create(),
* but in single-threaded case it is ensured to have at least one worker thread to run on
* (i.e. you don't have to call #BLI_task_pool_work_and_wait
* on it to be sure it will be processed).
*
* \note Background pools are non-recursive
* (that is, you should not create other background pools in tasks assigned to a background pool,
* they could end never being executed, since the 'fallback' background thread is already
* busy with parent task in single-threaded context).
*/
TaskPool *BLI_task_pool_create_background(void *userdata, TaskPriority priority)
{
return task_pool_create_ex(userdata, TASK_POOL_BACKGROUND, priority);
}
/**
* Similar to BLI_task_pool_create() but does not schedule any tasks for execution
* for until BLI_task_pool_work_and_wait() is called. This helps reducing threading
* overhead when pushing huge amount of small initial tasks from the main thread.
*/
TaskPool *BLI_task_pool_create_suspended(void *userdata, TaskPriority priority)
{
return task_pool_create_ex(userdata, TASK_POOL_TBB_SUSPENDED, priority);
}
/**
* Single threaded task pool that executes pushed task immediately, for
* debugging purposes.
*/
TaskPool *BLI_task_pool_create_no_threads(void *userdata)
{
return task_pool_create_ex(userdata, TASK_POOL_NO_THREADS, TASK_PRIORITY_HIGH);
}
/**
* Task pool that executes one task after the other, possibly on different threads
* but never in parallel.
*/
TaskPool *BLI_task_pool_create_background_serial(void *userdata, TaskPriority priority)
{
return task_pool_create_ex(userdata, TASK_POOL_BACKGROUND_SERIAL, priority);
}
void BLI_task_pool_free(TaskPool *pool)
{
switch (pool->type) {
case TASK_POOL_TBB:
case TASK_POOL_TBB_SUSPENDED:
case TASK_POOL_NO_THREADS:
tbb_task_pool_free(pool);
break;
case TASK_POOL_BACKGROUND:
case TASK_POOL_BACKGROUND_SERIAL:
background_task_pool_free(pool);
break;
}
BLI_mutex_end(&pool->user_mutex);
MEM_freeN(pool);
}
void BLI_task_pool_push(TaskPool *pool,
TaskRunFunction run,
void *taskdata,
bool free_taskdata,
TaskFreeFunction freedata)
{
Task task(pool, run, taskdata, free_taskdata, freedata);
switch (pool->type) {
case TASK_POOL_TBB:
case TASK_POOL_TBB_SUSPENDED:
case TASK_POOL_NO_THREADS:
tbb_task_pool_run(pool, std::move(task));
break;
case TASK_POOL_BACKGROUND:
case TASK_POOL_BACKGROUND_SERIAL:
background_task_pool_run(pool, std::move(task));
break;
}
}
void BLI_task_pool_work_and_wait(TaskPool *pool)
{
switch (pool->type) {
case TASK_POOL_TBB:
case TASK_POOL_TBB_SUSPENDED:
case TASK_POOL_NO_THREADS:
tbb_task_pool_work_and_wait(pool);
break;
case TASK_POOL_BACKGROUND:
case TASK_POOL_BACKGROUND_SERIAL:
background_task_pool_work_and_wait(pool);
break;
}
}
void BLI_task_pool_cancel(TaskPool *pool)
{
switch (pool->type) {
case TASK_POOL_TBB:
case TASK_POOL_TBB_SUSPENDED:
case TASK_POOL_NO_THREADS:
tbb_task_pool_cancel(pool);
break;
case TASK_POOL_BACKGROUND:
case TASK_POOL_BACKGROUND_SERIAL:
background_task_pool_cancel(pool);
break;
}
}
bool BLI_task_pool_canceled(TaskPool *pool)
{
switch (pool->type) {
case TASK_POOL_TBB:
case TASK_POOL_TBB_SUSPENDED:
case TASK_POOL_NO_THREADS:
return tbb_task_pool_canceled(pool);
case TASK_POOL_BACKGROUND:
case TASK_POOL_BACKGROUND_SERIAL:
return background_task_pool_canceled(pool);
}
BLI_assert("BLI_task_pool_canceled: Control flow should not come here!");
return false;
}
void *BLI_task_pool_user_data(TaskPool *pool)
{
return pool->userdata;
}
ThreadMutex *BLI_task_pool_user_mutex(TaskPool *pool)
{
return &pool->user_mutex;
}
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