{"templates":[{"name":"First Message Passing Example","description":"Calculates factorials using message passing.","content":"void factorial(intchan c) {\n    int z, j, n;\n    while (true) {\n        z = <? c; // receive input\n\n        n = 1;\n        for (j = z; j > 0 ; j--) {\n            n= n*j; \n        }\n\n        c <! n; // send result\n    };\n}\n\nmainAgent {\n    intchan cc;\n    agent a = start(factorial(cc));\n    cc <! 3;\n    int mid = <? cc;\n    println(\"3! evaluates to \" + mid + \".\");\n    cc <! mid;\n    println(\"(3!)! evaluates to \" + (<? cc) + \".\");\n}\n"},{"name":"Concurrent Counting with Mutex","description":"Decreases a counter with two threads. The counter is guarded by a Mutex. From the Concurrent Programming lecture.","content":"int n; // guarded by g\nlock g;\n\nvoid zaehler() {\n    int loop;\n    for (loop = 0; loop < 5; loop++) {\n        lock(g);\n        n = n - 1;\n        unlock(g);\n    }\n}\n\nmainAgent {\n    n = 10;\n    \n    agent a1 = start(zaehler());\n    agent a2 = start(zaehler());\n    join(a1);\n    join(a2);\n    \n    println(\"Der Wert ist \" + n);\n}"},{"name":"RWMutex","description":"An implementation of a Mutex that distinguishes between (shared) reading and (exclusive) writing.","content":"monitor RWMutex {\n    int locked = 0;       // how many times is the lock locked?\n    bool rwLock = false;  // locked for read+write-access?\n    int waitingForRW = 0; // how many are waiting for read+write?\n    \n    condition lockFreeForReaders with (rwLock == false && waitingForRW < 1);\n    condition lockFreeForWriters with (locked < 1);\n    \n    void lockWrite() {\n        // we need to wait\n        waitingForRW++;\n        waitForCondition(lockFreeForWriters);\n        locked++; // we got the lock\n        rwLock = true;\n        waitingForRW--;\n    }\n    \n    void lockRead() {\n        waitForCondition(lockFreeForReaders);\n        locked++; // we got the lock\n    }\n    \n    void unlockWrite() {\n        locked--;\n        rwLock = false;\n        signal(lockFreeForWriters);\n        signalAll(lockFreeForReaders);\n    }\n    \n    void unlockRead() {\n        locked--;\n        signal(lockFreeForWriters);\n    }\n}\n\nmainAgent {\n    // your code here\n}\n"},{"name":"Two Agents","description":"A minimal example of two agents with two global variables, suitable for memory model analysis.","content":"int x = 0;\nint y = 0;\n\nvoid agent1() {\n    \n}\n\nvoid agent2() {\n    \n}\n\nmainAgent {\n    start(agent1());\n    start(agent2());\n}\n"}]}