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https://github.com/switchbrew/libnx.git
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afe030f08b
Implements rwlockTryReadLock and rwlockTryWriteLock. Also implements rwlockIsWriteLockHeldByCurrentThread and rwlockIsOwnedByCurrentThread. Also re-designs RwLock to have semantics identical to Nintendo's (nn::os::ReaderWriterLock). The upshot is mostly that the lock is now fully recursive/write-preferring.
81 lines
2.1 KiB
C
81 lines
2.1 KiB
C
/**
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* @file rwlock.h
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* @brief Read/write lock synchronization primitive.
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* @author plutoo, SciresM
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* @copyright libnx Authors
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*/
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#pragma once
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#include "../kernel/mutex.h"
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#include "../kernel/condvar.h"
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/// Read/write lock structure.
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typedef struct {
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Mutex mutex;
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CondVar condvar_reader_wait;
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CondVar condvar_writer_wait;
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u32 read_lock_count;
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u32 read_waiter_count;
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u32 write_lock_count;
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u32 write_waiter_count;
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u32 write_owner_tag;
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} RwLock;
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/**
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* @brief Initializes the read/write lock.
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* @param r Read/write lock object.
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*/
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void rwlockInit(RwLock* r);
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/**
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* @brief Locks the read/write lock for reading.
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* @param r Read/write lock object.
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*/
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void rwlockReadLock(RwLock* r);
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/**
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* @brief Attempts to lock the read/write lock for reading without waiting.
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* @param r Read/write lock object.
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* @return 1 if the mutex has been acquired successfully, and 0 on contention.
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*/
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bool rwlockTryReadLock(RwLock* r);
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/**
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* @brief Unlocks the read/write lock for reading.
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* @param r Read/write lock object.
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*/
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void rwlockReadUnlock(RwLock* r);
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/**
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* @brief Locks the read/write lock for writing.
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* @param r Read/write lock object.
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*/
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void rwlockWriteLock(RwLock* r);
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/**
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* @brief Attempts to lock the read/write lock for writing without waiting.
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* @param r Read/write lock object.
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* @return 1 if the mutex has been acquired successfully, and 0 on contention.
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*/
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bool rwlockTryWriteLock(RwLock* r);
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/**
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* @brief Unlocks the read/write lock for writing.
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* @param r Read/write lock object.
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*/
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void rwlockWriteUnlock(RwLock* r);
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/**
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* @brief Checks if the write lock is held by the current thread.
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* @param r Read/write lock object.
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* @return 1 if the current hold holds the write lock, and 0 if it does not.
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*/
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bool rwlockIsWriteLockHeldByCurrentThread(RwLock* r);
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/**
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* @brief Checks if the read/write lock is owned by the current thread.
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* @param r Read/write lock object.
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* @return 1 if the current hold holds the write lock or if it holds read locks acquired
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* while it held the write lock, and 0 if it does not.
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*/
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bool rwlockIsOwnedByCurrentThread(RwLock* r);
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