| Directory: | ./ |
|---|---|
| File: | include/hpp/corbaserver/read-write-lock.hh |
| Date: | 2024-09-11 11:37:19 |
| Exec | Total | Coverage | |
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| Lines: | 34 | 35 | 97.1% |
| Branches: | 12 | 24 | 50.0% |
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| 1 | // Copyright (C) 2023 by Joseph Mirabel | ||
| 2 | // | ||
| 3 | // This code was taken from https://stackoverflow.com/a/28121513 | ||
| 4 | |||
| 5 | #include <condition_variable> | ||
| 6 | #include <mutex> | ||
| 7 | |||
| 8 | namespace hpp { | ||
| 9 | namespace corbaServer { | ||
| 10 | |||
| 11 | /// Synchronization class that ensures the following. | ||
| 12 | /// - A Write block Weads and Writes. | ||
| 13 | /// - Reads are only blocked by Writes, not by other Reads. | ||
| 14 | /// - Write is favored over Reads. | ||
| 15 | /// | ||
| 16 | /// This code was taken from https://stackoverflow.com/a/28121513 | ||
| 17 | class ReadWriteLock { | ||
| 18 | public: | ||
| 19 | 8 | ReadWriteLock() | |
| 20 | 8 | : shared_(), | |
| 21 | 8 | readerQ_(), | |
| 22 | 8 | writerQ_(), | |
| 23 | 8 | activeReaders_(0), | |
| 24 | 8 | waitingWriters_(0), | |
| 25 | 8 | activeWriters_(0) {} | |
| 26 | |||
| 27 | 12 | void readLock() { | |
| 28 |
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12 | std::unique_lock<std::mutex> lk(shared_); |
| 29 |
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12 | while (waitingWriters_ != 0) readerQ_.wait(lk); |
| 30 | 12 | ++activeReaders_; | |
| 31 |
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12 | lk.unlock(); |
| 32 | 12 | } | |
| 33 | |||
| 34 | 12 | void readUnlock() { | |
| 35 |
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12 | std::unique_lock<std::mutex> lk(shared_); |
| 36 | 12 | --activeReaders_; | |
| 37 |
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12 | lk.unlock(); |
| 38 | 12 | writerQ_.notify_one(); | |
| 39 | 12 | } | |
| 40 | |||
| 41 | 9 | void writeLock() { | |
| 42 |
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9 | std::unique_lock<std::mutex> lk(shared_); |
| 43 | 9 | ++waitingWriters_; | |
| 44 |
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9 | while (activeReaders_ != 0 || activeWriters_ != 0) writerQ_.wait(lk); |
| 45 | 9 | ++activeWriters_; | |
| 46 |
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9 | lk.unlock(); |
| 47 | 9 | } | |
| 48 | |||
| 49 | 9 | void writeUnlock() { | |
| 50 |
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9 | std::unique_lock<std::mutex> lk(shared_); |
| 51 | 9 | --waitingWriters_; | |
| 52 | 9 | --activeWriters_; | |
| 53 |
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9 | if (waitingWriters_ > 0) |
| 54 | ✗ | writerQ_.notify_one(); | |
| 55 | else | ||
| 56 | 9 | readerQ_.notify_all(); | |
| 57 |
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9 | lk.unlock(); |
| 58 | 9 | } | |
| 59 | |||
| 60 | private: | ||
| 61 | std::mutex shared_; | ||
| 62 | std::condition_variable readerQ_; | ||
| 63 | std::condition_variable writerQ_; | ||
| 64 | int activeReaders_; | ||
| 65 | int waitingWriters_; | ||
| 66 | int activeWriters_; | ||
| 67 | }; | ||
| 68 | |||
| 69 | } // end of namespace corbaServer. | ||
| 70 | } // end of namespace hpp. | ||
| 71 |