Dekker's Algorithm is a solution to the mutual exclusion problem in computer science. It allows multiple processes to share a common resource without conflicts.
*Problem Statement:*
Two or more processes want to access a shared resource, but only one process can access it at a time.
*Dekker's Algorithm:*
1. Two processes, P0 and P1, want to access the shared resource.
2. Each process has a flag variable (flag0 and flag1) initialized to false.
3. Process P0 sets flag0 to true and checks flag1. If flag1 is true, P0 waits.
4. Process P1 sets flag1 to true and checks flag0. If flag0 is true, P1 waits.
5. If a process finds the other process's flag false, it enters the critical section (accesses the shared resource).
6. After accessing the resource, the process sets its flag to false.
*Key Points:*
1. Dekker's Algorithm ensures mutual exclusion (only one process accesses the resource at a time).
2. It uses flag variables to communicate between processes.
3. A process waits if it finds the other process's flag true.
*Example:*
```
// Process P0
flag0 = true;
while (flag1) { /* wait */ }
// Critical section
flag0 = false;
// Process P1
flag1 = true;
while (flag0) { /* wait */ }
// Critical section
flag1 = false;
```
Dekker's Algorithm is a simple and efficient solution to the mutual exclusion problem, but it has some limitations, such as:
- It only works for two processes.
- It uses busy-waiting, which can waste CPU cycles.
More advanced algorithms, like Peterson's Algorithm and Lamport's Bakery Algorithm, have been developed to address these limitations.
