FM / tbb

/usr/include/oneapi/tbb

Name	Size	Mode	Actions
detail/	-	0755	rm
blocked_range.h	6453	0644	edit dl rm
blocked_range2d.h	3369	0644	edit dl rm
blocked_range3d.h	4455	0644	edit dl rm
blocked_rangeNd.h	5508	0644	edit dl rm
cache_aligned_allocator.h	6905	0644	edit dl rm
collaborative_call_once.h	9053	0644	edit dl rm
combinable.h	1969	0644	edit dl rm
concurrent_hash_map.h	71893	0644	edit dl rm
concurrent_lru_cache.h	13737	0644	edit dl rm
concurrent_map.h	13416	0644	edit dl rm
concurrent_priority_queue.h	19531	0644	edit dl rm
concurrent_queue.h	24030	0644	edit dl rm
concurrent_set.h	10241	0644	edit dl rm
concurrent_unordered_map.h	18697	0644	edit dl rm
concurrent_unordered_set.h	14850	0644	edit dl rm
concurrent_vector.h	46199	0644	edit dl rm
enumerable_thread_specific.h	42403	0644	edit dl rm
flow_graph.h	128339	0644	edit dl rm
flow_graph_abstractions.h	1446	0644	edit dl rm
global_control.h	6139	0644	edit dl rm
info.h	4179	0644	edit dl rm
memory_pool.h	9973	0644	edit dl rm
mutex.h	2628	0644	edit dl rm
null_mutex.h	2149	0644	edit dl rm
null_rw_mutex.h	2514	0644	edit dl rm
parallel_for.h	23451	0644	edit dl rm
parallel_for_each.h	27064	0644	edit dl rm
parallel_invoke.h	7783	0644	edit dl rm
parallel_pipeline.h	5755	0644	edit dl rm
parallel_reduce.h	37078	0644	edit dl rm
parallel_scan.h	22810	0644	edit dl rm
parallel_sort.h	11114	0644	edit dl rm
partitioner.h	28500	0644	edit dl rm
profiling.h	10005	0644	edit dl rm
queuing_mutex.h	6391	0644	edit dl rm
queuing_rw_mutex.h	6631	0644	edit dl rm
rw_mutex.h	8150	0644	edit dl rm
scalable_allocator.h	11655	0644	edit dl rm
spin_mutex.h	3513	0644	edit dl rm
spin_rw_mutex.h	7839	0644	edit dl rm
task.h	1090	0644	edit dl rm
task_arena.h	17853	0644	edit dl rm
task_group.h	27329	0644	edit dl rm
task_scheduler_observer.h	4585	0644	edit dl rm
tbbmalloc_proxy.h	1907	0644	edit dl rm
tbb_allocator.h	3782	0644	edit dl rm
tick_count.h	3201	0644	edit dl rm
version.h	4007	0644	edit dl rm

Edit: /usr/include/oneapi/tbb/rw_mutex.h (8150B)

/*
    Copyright (c) 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_rw_mutex_H
#define __TBB_rw_mutex_H

#if __TBB_PREVIEW_MUTEXES

#include "detail/_namespace_injection.h"
#include "detail/_utils.h"
#include "detail/_waitable_atomic.h"
#include "detail/_scoped_lock.h"
#include "detail/_mutex_common.h"
#include "profiling.h"

namespace tbb {
namespace detail {
namespace d1 {

class rw_mutex {
public:
    //! Constructors
    rw_mutex() noexcept : m_state(0) {
       create_itt_sync(this, "tbb::rw_mutex", "");
    }

//! Destructor
    ~rw_mutex() {
        __TBB_ASSERT(!m_state.load(std::memory_order_relaxed), "destruction of an acquired mutex");
    }

//! No Copy
    rw_mutex(const rw_mutex&) = delete;
    rw_mutex& operator=(const rw_mutex&) = delete;

using scoped_lock = rw_scoped_lock<rw_mutex>;

//! Mutex traits
    static constexpr bool is_rw_mutex = true;
    static constexpr bool is_recursive_mutex = false;
    static constexpr bool is_fair_mutex = false;

//! Acquire lock
    void lock() {
        call_itt_notify(prepare, this);
        while (!try_lock()) {
            if (!(m_state.load(std::memory_order_relaxed) & WRITER_PENDING)) { // no pending writers
                m_state |= WRITER_PENDING;
            }

auto wakeup_condition = [&] { return !(m_state.load(std::memory_order_relaxed) & BUSY); };
            adaptive_wait_on_address(this, wakeup_condition, WRITER_CONTEXT);
        }

call_itt_notify(acquired, this);
    }

//! Try acquiring lock (non-blocking)
    /** Return true if lock acquired; false otherwise. */
    bool try_lock() {
        // for a writer: only possible to acquire if no active readers or writers
        // Use relaxed memory fence is OK here because
        // Acquire memory fence guaranteed by compare_exchange_strong()
        state_type s = m_state.load(std::memory_order_relaxed);
        if (!(s & BUSY)) { // no readers, no writers; mask is 1..1101
            if (m_state.compare_exchange_strong(s, WRITER)) {
                call_itt_notify(acquired, this);
                return true; // successfully stored writer flag
            }
        }
        return false;
    }

//! Release lock
    void unlock() {
        call_itt_notify(releasing, this);
        state_type curr_state = (m_state &= READERS | WRITER_PENDING); // Returns current state

if (curr_state & WRITER_PENDING) {
            r1::notify_by_address(this, WRITER_CONTEXT);
        } else {
            // It's possible that WRITER sleeps without WRITER_PENDING,
            // because other thread might clear this bit at upgrade()
            r1::notify_by_address_all(this);
        }
    }

//! Lock shared ownership mutex
    void lock_shared() {
        call_itt_notify(prepare, this);
        while (!try_lock_shared()) {
            state_type has_writer = WRITER | WRITER_PENDING;
            auto wakeup_condition = [&] { return !(m_state.load(std::memory_order_relaxed) & has_writer); };
            adaptive_wait_on_address(this, wakeup_condition, READER_CONTEXT);
        }
        __TBB_ASSERT(m_state.load(std::memory_order_relaxed) & READERS, "invalid state of a read lock: no readers");
    }

//! Try lock shared ownership mutex
    bool try_lock_shared() {
        // for a reader: acquire if no active or waiting writers
        // Use relaxed memory fence is OK here because
        // Acquire memory fence guaranteed by fetch_add()
        state_type has_writer = WRITER | WRITER_PENDING;
        if (!(m_state.load(std::memory_order_relaxed) & has_writer)) {
            if (m_state.fetch_add(ONE_READER) & has_writer) {
                m_state -= ONE_READER;
                r1::notify_by_address(this, WRITER_CONTEXT);
            } else {
                call_itt_notify(acquired, this);
                return true; // successfully stored increased number of readers
            }
        }
        return false;
    }

//! Unlock shared ownership mutex
    void unlock_shared() {
        __TBB_ASSERT(m_state.load(std::memory_order_relaxed) & READERS, "invalid state of a read lock: no readers");
        call_itt_notify(releasing, this);

state_type curr_state = (m_state -= ONE_READER); // Returns current state

if (curr_state & (WRITER_PENDING)) {
            r1::notify_by_address(this, WRITER_CONTEXT);
        } else {
            // It's possible that WRITER sleeps without WRITER_PENDING,
            // because other thread might clear this bit at upgrade()
            r1::notify_by_address_all(this);
        }
    }

private:
    /** Internal non ISO C++ standard API **/
    //! This API is used through the scoped_lock class

//! Upgrade reader to become a writer.
    /** Returns whether the upgrade happened without releasing and re-acquiring the lock */
    bool upgrade() {
        state_type s = m_state.load(std::memory_order_relaxed);
        __TBB_ASSERT(s & READERS, "invalid state before upgrade: no readers ");
        // Check and set writer-pending flag.
        // Required conditions: either no pending writers, or we are the only reader
        // (with multiple readers and pending writer, another upgrade could have been requested)
        while ((s & READERS) == ONE_READER || !(s & WRITER_PENDING)) {
            if (m_state.compare_exchange_strong(s, s | WRITER | WRITER_PENDING)) {
                auto wakeup_condition = [&] { return (m_state.load(std::memory_order_relaxed) & READERS) == ONE_READER; };
                while ((m_state.load(std::memory_order_relaxed) & READERS) != ONE_READER) {
                    adaptive_wait_on_address(this, wakeup_condition, WRITER_CONTEXT);
                }

__TBB_ASSERT((m_state.load(std::memory_order_relaxed) & (WRITER_PENDING|WRITER)) == (WRITER_PENDING | WRITER),
                             "invalid state when upgrading to writer");
                // Both new readers and writers are blocked at this time
                m_state -= (ONE_READER + WRITER_PENDING);
                return true; // successfully upgraded
            }
        }
        // Slow reacquire
        unlock_shared();
        lock();
        return false;
    }

//! Downgrade writer to a reader
    void downgrade() {
        __TBB_ASSERT(m_state.load(std::memory_order_relaxed) & WRITER, nullptr),
        call_itt_notify(releasing, this);
        m_state += (ONE_READER - WRITER);

if (!(m_state & WRITER_PENDING)) {
            r1::notify_by_address(this, READER_CONTEXT);
        }

__TBB_ASSERT(m_state.load(std::memory_order_relaxed) & READERS, "invalid state after downgrade: no readers");
    }

using state_type = std::intptr_t;
    static constexpr state_type WRITER = 1;
    static constexpr state_type WRITER_PENDING = 2;
    static constexpr state_type READERS = ~(WRITER | WRITER_PENDING);
    static constexpr state_type ONE_READER = 4;
    static constexpr state_type BUSY = WRITER | READERS;

using context_type = std::uintptr_t;
    static constexpr context_type WRITER_CONTEXT = 0;
    static constexpr context_type READER_CONTEXT = 1;
    friend scoped_lock;
    //! State of lock
    /** Bit 0 = writer is holding lock
        Bit 1 = request by a writer to acquire lock (hint to readers to wait)
        Bit 2..N = number of readers holding lock */
    std::atomic<state_type> m_state;
}; // class rw_mutex

} // namespace d1
} // namespace detail

inline namespace v1 {
using detail::d1::rw_mutex;
} // namespace v1

} // namespace tbb

#endif /* __TBB_PREVIEW_MUTEXES */

#endif // __TBB_rw_mutex_H

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