P2P??????? ????????????????

1
P2P???????????????????????

• ??????
• ????????
• ??? ?

2
P2P??????? ????????????????

• ????
• P2P??????????????????????
• ??????????????????
• ????

3
1. ????
P2P??????? ????????????????

• ?????????????????????
• ?????
• Lamport, Ricart and Agrawala, Suzuki and Kasami,
  Maekawa,
• Raymond , Agrawal and El Abbadi
• Tree, O(log n) ?????? ? P2P ??????
• ?? ?
• LOTOS????????????????????
• ??? ?
• P2P ????????????

4
Fischer???????
P2P??????? ????????????????
repeat await ltp0gt ltpigt ltdelaygt until
ltpigt critical section p0
p?????i??? ??
5
P2P??????? ????????????????

• ??????p???
• ? ???????????????
• ??(contention)????????O(n)???
• ?
• ??????????
• ?????(Balking pattern)
• P2P?????(reliable multicast)
• O(log n)????critical section
• 80????????

6
2. P2P??????? ???????????????2.1
???????(?????)
P2P??????? ????????????????

• 2(h-1)?n?2h -1
• ?????????
• O(log n)

h
7
2. P2P??????? ???????????????2.2 ??????
P2P??????? ????????????????

• ???????(Dijkstra ?????????)
• Fisher ??????????
• node 1
• p???????? broadcast
• node 1 ??
• CS ??????node ??? node 1 ????
• node 1 ??p???????

8
node 1
P2P??????? ????????????????
integer p0..n initialize p0
9
node 1
P2P??????? ????????????????
when this request the critical section, do if
p0 then begin p1 broadcast 1
critical section p0 broadcast
0 / release / end od
10
node 1
P2P??????? ????????????????
when this received x, do if x0 or p0 then
begin px broadcast x
end / otherwise, the node p is already being
to enter the critical section / od
11
node i (2?i?n)
P2P??????? ????????????????
integer p0..n initialize p0
12
node i (2?i?n)
P2P??????? ????????????????
when this request the critical section, do if
p0 then begin send i to node 1 end od
13
node i (2?i?n)
P2P??????? ????????????????
when this received x, do px if pi then
begin critical section send 0 to node
1 / release / end od
14
2.3 critical section ??????????????1?????????
P2P??????? ????????????????

• ????

node 1
Critical section(CS) ??????????0
15
P2P??????? ????????????????

• ??1, node x ? CS ???

node 1
node x
node x ? S1???????????CS ????1?? ??????CS ?????
16
P2P??????? ????????????????

• ??2, node x ? CS ????

node x
S1 (px)
CS?????????0?
17
P2P??????? ????????????????

• ??3, node y ? CS???

node y ? S3???????????CS ????1?? ??????CS
????????????2?
18
2.4 critical section ?????
P2P??????? ????????????????

• ?????O(log n)
• ???????? O(log n) ? ??O(log n)
• CS ??????????

19
2.5 ??(contention)???
P2P??????? ????????????????

• node 1 ? x (?0)?broadcast ???O(log n)??p0
  ?????0?
• p?0??????CS????????
• (Balking Pattern)
• ???cs?????????????????????????????node 1????
• ?? ??????????? starvation free ?????FCFS?????
• ???????????????????????

20
3.??????????????????
P2P??????? ????????????????

• ?????????????????
• Draw, ?????????, Web??????????????????
• ????????????????????

21
P2P???????????????????????
22
??????????????????Critical Section
?????????(??????)
P2P??????? ????????????????
23
4. ????
P2P??????? ????????????????

• P2P???????????????????????
• ????????????
• 80??????????
• 80??????????????????
• ????????????

24
P2P??????? ????????????????

• ??
• ?????????????
• ???, ???
• www.tobata.isc.kyutech.ac.jp/yamanoue/
  researches/dsr/