Synchronization Primitives: Difference between revisions
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* Shared readers/Single writer approach of resource locking: many process may be reading a table at the same time, but only one can write at a time and it should prevent readers to access the table until the table has returned to a consistent state.
== Semaphores ==
Semaphores are one of the oldest and most widely used methods of ensuring [[Mutual Exclusion]] between two or more processes. A semaphore is a special integer variable which is (usually) initialized to 1, and can only altered by a pair of functions. Each of these functions, historically called
The function ''p'', also called <tt>wait()</tt> (or <tt>test()</tt>), decrements the value of the semaphore, and if the semaphore is negative, puts the process on the waiting queue until the semaphore is released by the process holding it.
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==See Also==
===Threads===
*[[Topic:9440|Userland only Semaphores
*[[Topic:10363|Spinlocks that disable interrupts
*[[Topic:9699|SMP compatibility
*[[Topic:14261|Mutex Implementation]]
*[[Topic:11903|Mutexs, Spinlocks and all that jazz]]
*[[Topic:7500|Spinlocks & Semaphores]]
[[Category:IPC]]
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