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#pragma once
#include "../taskflow.hpp"
namespace tf {
namespace detail {
// Function: find_if_loop
template <typename Iterator, typename Predicate>
bool find_if_loop(
std::atomic<size_t>& offset,
Iterator& beg,
size_t& prev_e,
size_t curr_b,
size_t curr_e,
Predicate predicate
) {
// early prune
if(offset.load(std::memory_order_relaxed) < curr_b) {
return true;
}
std::advance(beg, curr_b - prev_e);
for(size_t x = curr_b; x<curr_e; x++) {
if(predicate(*beg++)) {
atomic_min(offset, x);
return true;
}
}
prev_e = curr_e;
return false;
}
// Function: find_if_not_loop
template <typename Iterator, typename Predicate>
bool find_if_not_loop(
std::atomic<size_t>& offset,
Iterator& beg,
size_t& prev_e,
size_t curr_b,
size_t curr_e,
Predicate predicate
) {
// early prune
if(offset.load(std::memory_order_relaxed) < curr_b) {
return true;
}
std::advance(beg, curr_b - prev_e);
for(size_t x = curr_b; x<curr_e; x++) {
if(!predicate(*beg++)) {
atomic_min(offset, x);
return true;
}
}
prev_e = curr_e;
return false;
}
} // namespace detail --------------------------------------------------------
// Function: make_find_if_task
template <typename B, typename E, typename T, typename UOP, typename P = DefaultPartitioner>
auto make_find_if_task(B first, E last, T& result, UOP predicate, P part = P()) {
using namespace std::string_literals;
using B_t = std::decay_t<unwrap_ref_decay_t<B>>;
using E_t = std::decay_t<unwrap_ref_decay_t<E>>;
return [=, &result] (Runtime& rt) mutable {
// fetch the stateful values
B_t beg = first;
E_t end = last;
size_t W = rt.executor().num_workers();
size_t N = std::distance(beg, end);
// only myself - no need to spawn another graph
if(W <= 1 || N <= part.chunk_size()) {
part([&](){ result = std::find_if(beg, end, predicate); })();
return;
}
PreemptionGuard preemption_guard(rt);
// use no more workers than the iteration count
if(N < W) {
W = N;
}
// we leverage smart pointer to let the last task update the result
std::shared_ptr<std::atomic<size_t>> offset(
new std::atomic<size_t>(N),
[=, &result](std::atomic<size_t>* p) {
result = std::next(beg, p->load(std::memory_order_relaxed));
delete p;
}
);
// static partitioner
if constexpr(part.type() == PartitionerType::STATIC) {
for(size_t w=0, curr_b=0; w<W && curr_b < N;) {
auto chunk_size = part.adjusted_chunk_size(N, W, w);
auto task = part([=] () mutable {
part.loop_until(N, W, curr_b, chunk_size,
[=, &offset, prev_e=size_t{0}](size_t part_b, size_t part_e) mutable {
return detail::find_if_loop(
*offset, beg, prev_e, part_b, part_e, predicate
);
}
);
// must release the ownership before async is destroyed
// as the node deletion comes after the join counter reaches zero
offset.reset();
});
(++w == W || (curr_b += chunk_size) >= N) ? task() : rt.silent_async(task);
}
}
// dynamic partitioner
else {
auto next = std::make_shared<std::atomic<size_t>>(0);
for(size_t w=0; w<W;) {
auto task = part([=] () mutable {
part.loop_until(N, W, *next,
[=, &offset, prev_e=size_t{0}](size_t curr_b, size_t curr_e) mutable {
return detail::find_if_loop(
*offset, beg, prev_e, curr_b, curr_e, predicate
);
}
);
// must release the ownership before async is destroyed
// as the node deletion comes after the join counter reaches zero
offset.reset();
});
(++w == W) ? task() : rt.silent_async(task);
}
}
};
}
// Function: make_find_if_not_task
template <typename B, typename E, typename T, typename UOP, typename P = DefaultPartitioner>
auto make_find_if_not_task(B first, E last, T& result, UOP predicate, P part = P()) {
using namespace std::string_literals;
using B_t = std::decay_t<unwrap_ref_decay_t<B>>;
using E_t = std::decay_t<unwrap_ref_decay_t<E>>;
return [=, &result] (Runtime& rt) mutable {
// fetch the stateful values
B_t beg = first;
E_t end = last;
size_t W = rt.executor().num_workers();
size_t N = std::distance(beg, end);
// only myself - no need to spawn another graph
if(W <= 1 || N <= part.chunk_size()) {
part([&](){ result = std::find_if_not(beg, end, predicate); })();
return;
}
PreemptionGuard preemption_guard(rt);
if(N < W) {
W = N;
}
// we leverage smart pointer to let the last task update the result
std::shared_ptr<std::atomic<size_t>> offset(
new std::atomic<size_t>(N),
[=, &result](std::atomic<size_t>* p) {
result = std::next(beg, p->load(std::memory_order_relaxed));
delete p;
}
);
// static partitioner
if constexpr(part.type() == PartitionerType::STATIC) {
for(size_t w=0, curr_b=0; w<W && curr_b < N;) {
auto chunk_size = part.adjusted_chunk_size(N, W, w);
auto task = part([=] () mutable {
part.loop_until(N, W, curr_b, chunk_size,
[=, &offset, prev_e=size_t{0}](size_t part_b, size_t part_e) mutable {
return detail::find_if_not_loop(
*offset, beg, prev_e, part_b, part_e, predicate
);
}
);
// must release the ownership before async is destroyed
// as the node deletion comes after the join counter reaches zero
offset.reset();
});
(++w == W || (curr_b += chunk_size) >= N) ? task() : rt.silent_async(task);
}
}
// dynamic partitioner
else {
auto next = std::make_shared<std::atomic<size_t>>(0);
for(size_t w=0; w<W;) {
auto task = part([=] () mutable {
part.loop_until(N, W, *next,
[=, &offset, prev_e=size_t{0}](size_t curr_b, size_t curr_e) mutable {
return detail::find_if_not_loop(
*offset, beg, prev_e, curr_b, curr_e, predicate
);
}
);
// must release the ownership before async is destroyed
// as the node deletion comes after the join counter reaches zero
offset.reset();
});
(++w == W) ? task() : rt.silent_async(task);
}
}
};
}
// Function: make_min_element_task
template <typename B, typename E, typename T, typename C, typename P = DefaultPartitioner>
auto make_min_element_task(B first, E last, T& result, C comp, P part = P()) {
using namespace std::string_literals;
using B_t = std::decay_t<unwrap_ref_decay_t<B>>;
using E_t = std::decay_t<unwrap_ref_decay_t<E>>;
return [=, &result] (Runtime& rt) mutable {
// fetch the iterator values
B_t beg = first;
E_t end = last;
size_t W = rt.executor().num_workers();
size_t N = std::distance(beg, end);
// only myself - no need to spawn another graph
if(W <= 1 || N <= part.chunk_size()) {
part([&](){ result = std::min_element(beg, end, comp); })();
return;
}
PreemptionGuard preemption_guard(rt);
if(N < W) {
W = N;
}
auto mutex = std::make_shared<std::mutex>();
// initialize the result to the first element
result = beg++;
N--;
// static partitioner
if constexpr(part.type() == PartitionerType::STATIC) {
for(size_t w=0, curr_b=0; w<W && curr_b < N;) {
// we force chunk size to be at least two because the temporary
// variable sum needs to avoid copy at the first step
auto chunk_size = std::max(size_t{2}, part.adjusted_chunk_size(N, W, w));
auto task = part([=, &result] () mutable {
std::advance(beg, curr_b);
if(N - curr_b == 1) {
std::lock_guard<std::mutex> lock(*mutex);
if(comp(*beg, *result)) {
result = beg;
}
return;
}
auto beg1 = beg++;
auto beg2 = beg++;
T smallest = comp(*beg1, *beg2) ? beg1 : beg2;
// loop reduce
part.loop(N, W, curr_b, chunk_size,
[=, &smallest, prev_e=curr_b+2](size_t part_b, size_t part_e) mutable {
if(part_b > prev_e) {
std::advance(beg, part_b - prev_e);
}
else {
part_b = prev_e;
}
for(size_t x=part_b; x<part_e; x++, beg++) {
if(comp(*beg, *smallest)) {
smallest = beg;
}
}
prev_e = part_e;
}
);
// final reduce
std::lock_guard<std::mutex> lock(*mutex);
if(comp(*smallest, *result)) {
result = smallest;
}
});
(++w == W || (curr_b += chunk_size) >= N) ? task() : rt.silent_async(task);
}
}
// dynamic partitioner
else {
auto next = std::make_shared<std::atomic<size_t>>(0);
for(size_t w=0; w<W;) {
auto task = part([=, &result] () mutable {
// pre-reduce
size_t s0 = next->fetch_add(2, std::memory_order_relaxed);
if(s0 >= N) {
return;
}
std::advance(beg, s0);
if(N - s0 == 1) {
std::lock_guard<std::mutex> lock(*mutex);
if(comp(*beg, *result)) {
result = beg;
}
return;
}
auto beg1 = beg++;
auto beg2 = beg++;
T smallest = comp(*beg1, *beg2) ? beg1 : beg2;
// loop reduce
part.loop(N, W, *next,
[=, &smallest, prev_e=s0+2](size_t part_b, size_t part_e) mutable {
std::advance(beg, part_b - prev_e);
for(size_t x=part_b; x<part_e; x++, beg++) {
if(comp(*beg, *smallest)) {
smallest = beg;
}
}
prev_e = part_e;
}
);
// final reduce
std::lock_guard<std::mutex> lock(*mutex);
if(comp(*smallest, *result)) {
result = smallest;
}
});
(++w == W) ? task() : rt.silent_async(task);
}
}
};
}
// Function: make_max_element_task
template <typename B, typename E, typename T, typename C, typename P = DefaultPartitioner>
auto make_max_element_task(B first, E last, T& result, C comp, P part = P()) {
using namespace std::string_literals;
using B_t = std::decay_t<unwrap_ref_decay_t<B>>;
using E_t = std::decay_t<unwrap_ref_decay_t<E>>;
return [=, &result] (Runtime& rt) mutable {
// fetch the iterator values
B_t beg = first;
E_t end = last;
size_t W = rt.executor().num_workers();
size_t N = std::distance(beg, end);
// only myself - no need to spawn another graph
if(W <= 1 || N <= part.chunk_size()) {
part([&](){ result = std::max_element(beg, end, comp); })();
return;
}
PreemptionGuard preemption_guard(rt);
if(N < W) {
W = N;
}
auto mutex = std::make_shared<std::mutex>();
// initialize the result to the first element
result = beg++;
N--;
// static partitioner
if constexpr(part.type() == PartitionerType::STATIC) {
for(size_t w=0, curr_b=0; w<W && curr_b < N;) {
// we force chunk size to be at least two because the temporary
// variable sum needs to avoid copy at the first step
auto chunk_size = std::max(size_t{2}, part.adjusted_chunk_size(N, W, w));
auto task = part([=, &result] () mutable {
std::advance(beg, curr_b);
if(N - curr_b == 1) {
std::lock_guard<std::mutex> lock(*mutex);
if(comp(*result, *beg)) {
result = beg;
}
return;
}
auto beg1 = beg++;
auto beg2 = beg++;
T largest = comp(*beg1, *beg2) ? beg2 : beg1;
// loop reduce
part.loop(N, W, curr_b, chunk_size,
[=, &largest, prev_e=curr_b+2](size_t part_b, size_t part_e) mutable {
if(part_b > prev_e) {
std::advance(beg, part_b - prev_e);
}
else {
part_b = prev_e;
}
for(size_t x=part_b; x<part_e; x++, beg++) {
if(comp(*largest, *beg)) {
largest = beg;
}
}
prev_e = part_e;
}
);
// final reduce
std::lock_guard<std::mutex> lock(*mutex);
if(comp(*result, *largest)) {
result = largest;
}
});
(++w == W || (curr_b += chunk_size) >= N) ? task() : rt.silent_async(task);
}
}
// dynamic partitioner
else {
auto next = std::make_shared<std::atomic<size_t>>(0);
for(size_t w=0; w<W;) {
auto task = part([=, &result] () mutable {
// pre-reduce
size_t s0 = next->fetch_add(2, std::memory_order_relaxed);
if(s0 >= N) {
return;
}
std::advance(beg, s0);
if(N - s0 == 1) {
std::lock_guard<std::mutex> lock(*mutex);
if(comp(*result, *beg)) {
result = beg;
}
return;
}
auto beg1 = beg++;
auto beg2 = beg++;
T largest = comp(*beg1, *beg2) ? beg2 : beg1;
// loop reduce
part.loop(N, W, *next,
[=, &largest, prev_e=s0+2](size_t part_b, size_t part_e) mutable {
std::advance(beg, part_b - prev_e);
for(size_t x=part_b; x<part_e; x++, beg++) {
if(comp(*largest, *beg)) {
largest = beg;
}
}
prev_e = part_e;
}
);
// final reduce
std::lock_guard<std::mutex> lock(*mutex);
if(comp(*result, *largest)) {
result = largest;
}
});
(++w == W) ? task() : rt.silent_async(task);
}
}
};
}
// Function: find_if
template <typename B, typename E, typename T, typename UOP, typename P>
Task tf::FlowBuilder::find_if(B first, E last, T& result, UOP predicate, P part) {
return emplace(make_find_if_task(first, last, result, predicate, part));
}
// Function: find_if_not
template <typename B, typename E, typename T, typename UOP, typename P>
Task tf::FlowBuilder::find_if_not(B first, E last, T& result, UOP predicate, P part) {
return emplace(make_find_if_not_task(first, last, result, predicate, part));
}
// ----------------------------------------------------------------------------
// min_element
// ----------------------------------------------------------------------------
// Function: min_element
template <typename B, typename E, typename T, typename C, typename P>
Task FlowBuilder::min_element(B first, E last, T& result, C comp, P part) {
return emplace(make_min_element_task(first, last, result, comp, part));
}
// ----------------------------------------------------------------------------
// max_element
// ----------------------------------------------------------------------------
// Function: max_element
template <typename B, typename E, typename T, typename C, typename P>
Task FlowBuilder::max_element(B first, E last, T& result, C comp, P part) {
return emplace(make_max_element_task(first, last, result, comp, part));
}
} // end of namespace tf -----------------------------------------------------
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