Used for creating read and write locks.
Used for storing the amount of active read operations on a resource.
Used to generate identifiers with the given suffixes.
count is used for the identifier used to store the counter.
read and write are used for the 2 types of locks that are needed.
This identifier is used for storing the count of active read operations.
This is the identifier for the read lock: the lock that is used to safely update and read the count.
This is the identifier for the write lock, making sure there is at most 1 write operation active.
Updates the count with the given modifier. Creates the data if it didn't exist yet. Deletes the data when the count reaches zero.
Safely decreases the count after the read operation is finished.
Safely updates the count before starting a read operation.
Safely runs an action on the count.
A ReadWriteLocker that allows for multiple simultaneous read operations. Write operations will be blocked as long as read operations are not finished. New read operations are allowed while this is going on, which will cause write operations to wait longer.
Based on https://en.wikipedia.org/wiki/Readers%E2%80%93writer_lock#Using_two_mutexes . As soon as 1 read lock request is made, the write lock is locked. Internally a counter keeps track of the amount of active read locks. Only when this number reaches 0 will the write lock be released again. The internal read lock is only locked to increase/decrease this counter and is released afterwards. This allows for multiple read operations, although only 1 at the time can update the counter, which means there can still be a small waiting period if there are multiple simultaneous read operations.