You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
88 lines
2.6 KiB
88 lines
2.6 KiB
// synchronous leader election protocol (itai & Rodeh)
|
|
// dxp/gxn 25/01/01
|
|
// N=6 and K=4
|
|
|
|
probabilistic
|
|
|
|
// CONSTANTS
|
|
const N=7; // number of processes
|
|
const K=3; // range of probabilistic choice
|
|
|
|
// counter module used to count the number of processes that have been read
|
|
// and to know when a process has decided
|
|
module counter
|
|
|
|
// counter (c=i means process j reading process (i-1)+j next)
|
|
c : [1..N-1];
|
|
|
|
// reading
|
|
[read] c<N-1 -> (c'=c+1);
|
|
// finished reading
|
|
[read] c=N-1 -> (c'=c);
|
|
//decide
|
|
[done] u1 | u2 | u3 | u4 | u5 | u6 | u7 -> (c'=c);
|
|
// pick again reset counter
|
|
[retry] !(u1 | u2 | u3 | u4 | u5 | u6 | u7) -> (c'=1);
|
|
// loop (when finished to avoid deadlocks)
|
|
[loop] s1=3 -> (c'=c);
|
|
|
|
endmodule
|
|
|
|
// processes form a ring and suppose:
|
|
// process 1 reads process 2
|
|
// process 2 reads process 3
|
|
// process 3 reads process 1
|
|
module process1
|
|
|
|
// local state
|
|
s1 : [0..3];
|
|
// s1=0 make random choice
|
|
// s1=1 reading
|
|
// s1=2 deciding
|
|
// s1=3 finished
|
|
|
|
// has a unique id so far (initially true)
|
|
u1 : bool;
|
|
|
|
// value to be sent to next process in the ring (initially sets this to its own value)
|
|
v1 : [0..K-1];
|
|
|
|
// random choice
|
|
p1 : [0..K-1];
|
|
|
|
// pick value
|
|
[pick] s1=0 -> 1/K : (s1'=1) & (p1'=0) & (v1'=0) & (u1'=true)
|
|
+ 1/K : (s1'=1) & (p1'=1) & (v1'=1) & (u1'=true)
|
|
+ 1/K : (s1'=1) & (p1'=2) & (v1'=2) & (u1'=true);
|
|
// read
|
|
[read] s1=1 & u1 & !p1=v2 & c<N-1 -> (u1'=true) & (v1'=v2);
|
|
[read] s1=1 & u1 & p1=v2 & c<N-1 -> (u1'=false) & (v1'=v2) & (p1'=0);
|
|
[read] s1=1 & !u1 & c<N-1 -> (u1'=false) & (v1'=v2);
|
|
// read and move to decide
|
|
[read] s1=1 & u1 & !p1=v2 & c=N-1 -> (s1'=2) & (u1'=true) & (v1'=0) & (p1'=0);
|
|
[read] s1=1 & u1 & p1=v2 & c=N-1 -> (s1'=2) & (u1'=false) & (v1'=0) & (p1'=0);
|
|
[read] s1=1 & !u1 & c=N-1 -> (s1'=2) & (u1'=false) & (v1'=0);
|
|
// deciding
|
|
// done
|
|
[done] s1=2 -> (s1'=3) & (u1'=false) & (v1'=0) & (p1'=0);
|
|
//retry
|
|
[retry] s1=2 -> (s1'=0) & (u1'=false) & (v1'=0) & (p1'=0);
|
|
// loop (when finished to avoid deadlocks)
|
|
[loop] s1=3 -> (s1'=3);
|
|
|
|
endmodule
|
|
|
|
// construct remaining processes through renaming
|
|
module process2=process1[s1=s2,p1=p2,v1=v2,u1=u2,v2=v3] endmodule
|
|
module process3=process1[s1=s3,p1=p3,v1=v3,u1=u3,v2=v4] endmodule
|
|
module process4=process1[s1=s4,p1=p4,v1=v4,u1=u4,v2=v5] endmodule
|
|
module process5=process1[s1=s5,p1=p5,v1=v5,u1=u5,v2=v6] endmodule
|
|
module process6=process1[s1=s6,p1=p6,v1=v6,u1=u6,v2=v7] endmodule
|
|
module process7=process1[s1=s7,p1=p7,v1=v7,u1=u7,v2=v1] endmodule
|
|
|
|
// REWARDS -expected number of rounds
|
|
rewards
|
|
|
|
[pick] true : 1;
|
|
|
|
endrewards
|