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47 lines
1.0 KiB
C++
47 lines
1.0 KiB
C++
#pragma once
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#include <mutex>
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#include <condition_variable>
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namespace llarp
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{
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namespace util
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{
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/// Barrier class that blocks all threads until the high water mark of
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/// threads (set during construction) is reached, then releases them all.
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class Barrier
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{
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std::mutex mutex;
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std::condition_variable cv;
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unsigned pending;
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public:
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Barrier(unsigned threads) : pending{threads}
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{
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}
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/// Returns true if *this* Block call is the one that releases all of
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/// them; returns false (i.e. after unblocking) if some other thread
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/// triggered the released.
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bool
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Block()
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{
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std::unique_lock lock{mutex};
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if (pending == 1)
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{
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pending = 0;
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lock.unlock();
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cv.notify_all();
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return true;
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}
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else if (pending > 1)
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{
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pending--;
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}
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cv.wait(lock, [this] { return !pending; });
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return false;
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}
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};
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} // namespace util
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} // namespace llarp
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