/usr/include/oneapi/tbb/detail
Edit: /usr/include/oneapi/tbb/detail/_aggregator.h (7562B)
/*
Copyright (c) 2005-2021 Intel Corporation
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
#ifndef __TBB_detail__aggregator_H
#define __TBB_detail__aggregator_H
#include "_assert.h"
#include "_utils.h"
#include
#if !__TBBMALLOC_BUILD // TODO: check this macro with TBB Malloc
#include "../profiling.h"
#endif
namespace tbb {
namespace detail {
namespace d1 {
// Base class for aggregated operation
template
class aggregated_operation {
public:
// Zero value means "wait" status, all other values are "user" specified values and
// are defined into the scope of a class which uses "status"
std::atomic status;
std::atomic next;
aggregated_operation() : status{}, next(nullptr) {}
}; // class aggregated_operation
// Aggregator base class
/* An aggregator for collecting operations coming from multiple sources and executing
them serially on a single thread. OperationType must be derived from
aggregated_operation. The parameter HandlerType is a functor that will be passed the
list of operations and is expected to handle each operation appropriately, setting the
status of each operation to non-zero. */
template
class aggregator_generic {
public:
aggregator_generic() : pending_operations(nullptr), handler_busy(false) {}
// Execute an operation
/* Places an operation into the waitlist (pending_operations), and either handles the list,
or waits for the operation to complete, or returns.
The long_life_time parameter specifies the life time of the given operation object.
Operations with long_life_time == true may be accessed after execution.
A "short" life time operation (long_life_time == false) can be destroyed
during execution, and so any access to it after it was put into the waitlist,
including status check, is invalid. As a consequence, waiting for completion
of such operation causes undefined behavior. */
template
void execute( OperationType* op, HandlerType& handle_operations, bool long_life_time = true ) {
// op->status should be read before inserting the operation into the
// aggregator waitlist since it can become invalid after executing a
// handler (if the operation has 'short' life time.)
const uintptr_t status = op->status.load(std::memory_order_relaxed);
// ITT note: &(op->status) tag is used to cover accesses to this op node. This
// thread has created the operation, and now releases it so that the handler
// thread may handle the associated operation w/o triggering a race condition;
// thus this tag will be acquired just before the operation is handled in the
// handle_operations functor.
call_itt_notify(releasing, &(op->status));
// insert the operation in the queue.
OperationType* res = pending_operations.load(std::memory_order_relaxed);
do {
op->next.store(res, std::memory_order_relaxed);
} while (!pending_operations.compare_exchange_strong(res, op));
if (!res) { // first in the list; handle the operations
// ITT note: &pending_operations tag covers access to the handler_busy flag,
// which this waiting handler thread will try to set before entering
// handle_operations.
call_itt_notify(acquired, &pending_operations);
start_handle_operations(handle_operations);
// The operation with 'short' life time can already be destroyed
if (long_life_time)
__TBB_ASSERT(op->status.load(std::memory_order_relaxed), NULL);
}
// Not first; wait for op to be ready
else if (!status) { // operation is blocking here.
__TBB_ASSERT(long_life_time, "Waiting for an operation object that might be destroyed during processing");
call_itt_notify(prepare, &(op->status));
spin_wait_while_eq(op->status, uintptr_t(0));
}
}
private:
// Trigger the handling of operations when the handler is free
template
void start_handle_operations( HandlerType& handle_operations ) {
OperationType* op_list;
// ITT note: &handler_busy tag covers access to pending_operations as it is passed
// between active and waiting handlers. Below, the waiting handler waits until
// the active handler releases, and the waiting handler acquires &handler_busy as
// it becomes the active_handler. The release point is at the end of this
// function, when all operations in pending_operations have been handled by the
// owner of this aggregator.
call_itt_notify(prepare, &handler_busy);
// get the handler_busy:
// only one thread can possibly spin here at a time
spin_wait_until_eq(handler_busy, uintptr_t(0));
call_itt_notify(acquired, &handler_busy);
// acquire fence not necessary here due to causality rule and surrounding atomics
handler_busy.store(1, std::memory_order_relaxed);
// ITT note: &pending_operations tag covers access to the handler_busy flag
// itself. Capturing the state of the pending_operations signifies that
// handler_busy has been set and a new active handler will now process that list's
// operations.
call_itt_notify(releasing, &pending_operations);
// grab pending_operations
op_list = pending_operations.exchange(nullptr);
// handle all the operations
handle_operations(op_list);
// release the handler
handler_busy.store(0, std::memory_order_release);
}
// An atomically updated list (aka mailbox) of pending operations
std::atomic pending_operations;
// Controls threads access to handle_operations
std::atomic handler_busy;
}; // class aggregator_generic
template
class aggregator : public aggregator_generic {
HandlerType handle_operations;
public:
aggregator() = default;
void initialize_handler( HandlerType h ) { handle_operations = h; }
void execute(OperationType* op) {
aggregator_generic::execute(op, handle_operations);
}
}; // class aggregator
// the most-compatible friend declaration (vs, gcc, icc) is
// template friend class aggregating_functor;
template
class aggregating_functor {
AggregatingClass* my_object;
public:
aggregating_functor() = default;
aggregating_functor( AggregatingClass* object ) : my_object(object) {
__TBB_ASSERT(my_object, nullptr);
}
void operator()( OperationList* op_list ) { my_object->handle_operations(op_list); }
}; // class aggregating_functor
} // namespace d1
} // namespace detail
} // namespace tbb
#endif // __TBB_detail__aggregator_H