CS September 2018

Transcription

1 Loil los Distriut Systms 06. Loil los Assin squn numrs to msss All ooprtin prosss n r on orr o vnts vs. physil los: rport tim o y Assum no ntrl tim sour Eh systm mintins its own lol lo No totl orrin o vnts No onpt o hppn-whn Pul Krzyznowsi Rutrs Univrsity Fll 207 Assum multipl tors (prosss) Eh pross hs uniqu ID Eh pross hs its own inrmntin ountr 2 Hppn-or Lmport s hppn-or nottion vnt hppn or vnt..: : mss in snt, : mss ript Trnsitiv: i n thn Loil los & onurrny Assin lo vlu to h vnt i thn lo() < lo() sin tim nnot run wrs I n our on irnt prosss tht o not xhn msss, thn nithr nor r tru Ths vnts r onurrnt Othrwis, thy r usl 3 4 Thr systms: P 0, P, Evnts,,, Lol vnt ountr on h systm Systms osionlly ommunit P Pul Krzyznowsi

2 Lmport s lorithm Eh mss rris timstmp o th snr s lo P Whn mss rrivs: i rivr s lo < mss_timstmp st systm lo to (mss_timstmp + ) ls o nothin B orrin: à h ut 5 2 à ut 6 2 Clo must vn twn ny two vnts in th sm pross 7 8 Lmport s lorithm Alorithm llows us to mintin tim orrin mon rlt vnts Prtil orrin Applyin Lmport s lorithm P W hv oo orrin whr w us to hv orrin: à h n 5 < 6 à n 6 < Summry Alorithm ns monotonilly inrsin sotwr ountr Inrmnt t lst whn vnts tht n to timstmp our Eh vnt hs Lmport timstmp tth to it For ny two vnts, whr : L() < L() Prolm: Intil timstmps P 2,, : lol vnts squn i,,, : 6 7 Lmport imposs sn riv rltionship Conurrnt vnts (.., & ; i & ) my hv th sm timstmp or not 7 2 Pul Krzyznowsi 2

3 Uniqu timstmps (totl orrin) Uniqu (totlly orr) timstmps W n or h timstmp to uniqu Din lol loil timstmp (T i, i) T i rprsnts lol Lmport timstmp i rprsnts pross numr (lolly uniqu).., (host rss, pross ID) Compr timstmps: (T i, i) < (T, ) i n only i T i < T or T i = T n i < P Dos not nssrily rlt to tul vnt orrin 3 4 Prolm: Dttin usl rltions I L() < L( ) W nnot onlu tht Exmpl Group o prosss: Ali, Bo, Ciny, Dvi Thy onurrntly moiy on ot: wht shoul w t? Eh pross ps lol ountr By looin t Lmport timstmps W nnot onlu whih vnts r uslly rlt Ali writs th vlu & sns to roup Ali: Pizz To Bo To Ciny To Dvi Solution: us vtor lo Vtor los r wy to prov th squn o vnts t pin vrsion history s on h pross tht m hns to n ot Bo rs ("Pizz", <li:>), moiis th vlu & sns to roup To Ali Ali:, Bo: Chins Bo s vrsion upts Ali s To Ciny To Dvi Rivr <li:, o:> is usl to & ollows <li: > Ali rs ("Chins", <li:, o:>), moiis th vlu & sns to roup To Bo Ali: 2, Bo: Rivr To Ciny <li: 2, o:> is usl to & Moron ollows <li:, o:> To Dvi Ali ms hns ovr Bo s 5 6 Exmpl Vtor los Ciny moiis & sns to roup Ali: 2, Bo:, Ciny: Thi Bo onurrntly moiis & sns to roup Ali: 2, Bo: 2 Chins To Ali To Bo To Dvi To Ali To Ciny To Dvi Ciny & Bo s hns r onurrnt mmrs must rsolv onlit Rivr <li: 2, o:, iny:> is onurrnt with <li:, o:2> Ruls:. Vtor initiliz to 0 t h pross V i [ ] = 0 or i, =,, N 2. Pross inrmnts its lmnt o th vtor in lol vtor or timstmpin vnt: V i [ i ] = Vi [ i ] + 3. Mss is snt rom pross P i with V i tth to it 4. Whn P rivs mss, omprs vtors lmnt y lmnt n sts lol vtor to hihr o two vlus V [ i ] = mx(v i [ i ], V [ i ]) or I =,, N For xmpl, riv: [ 0, 5, 2, ], hv: [ 2, 8, 0, ] nw timstmp: [ 2, 8, 2, ] 7 8 Pul Krzyznowsi 3

4 Comprin vtor timstmps Vtor timstmps Din V = V i V [ i ] = V [ i ] V V i V [ i ] V [ i ] or i = N or i = N P For ny two vnts, i thn V() < V( ) ust li Lmport s lorithm i V() < V( ) thn Two vnts r onurrnt i nithr V() V( ) nor V( ) V() 9 20 Vtor timstmps Vtor timstmps (,0,0) P (,0,0) P Evnt timstmp (,0,0) Evnt timstmp (,0,0) 2 22 Vtor timstmps Vtor timstmps (,0,0) P (2,,0) (,0,0) P (2,,0) (2,2,0) Evnt timstmp (,0,0) (2,,0) Evnt timstmp (,0,0) (2,,0) (2,2,0) Pul Krzyznowsi 4

5 Vtor timstmps (,0,0) P (0,0,) (2,,0) (2,2,0) Vtor timstmps (,0,0) P (2,,0) (2,2,0) (0,0,) (2,2,2) Evnt timstmp (,0,0) (2,,0) (2,2,0) (0,0,) Evnt timstmp (,0,0) (2,,0) (2,2,0) (0,0,) (2,2,2) Vtor timstmps (,0,0) P (2,,0) (2,2,0) (0,0,) (2,2,2) Vtor timstmps (,0,0) P (2,,0) (2,2,0) (0,0,) (2,2,2) Evnt timstmp (,0,0) (2,,0) (2,2,0) (0,0,) (2,2,2) onurrnt vnts Evnt timstmp (,0,0) (2,,0) (2,2,0) (0,0,) (2,2,2) onurrnt vnts Vtor timstmps (,0,0) P (2,,0) (2,2,0) (0,0,) (2,2,2) Vtor timstmps (,0,0) P (2,,0) (2,2,0) (0,0,) (2,2,2) Evnt timstmp (,0,0) (2,,0) (2,2,0) (0,0,) (2,2,2) onurrnt vnts Evnt timstmp (,0,0) (2,,0) (2,2,0) (0,0,) (2,2,2) onurrnt vnts Pul Krzyznowsi 5

6 Gnrlizin Vtor Timstmps A vtor n list o tupls: For prosss P,,, Eh pross hs lolly uniqu Pross ID, P i (.., MAC_rss:PID) Eh pross mintins its own timstmp: T P, T P2, Vtor: { <P, T P >, <, T P2 >, <, T P3 >, } Any on pross my hv only prtil nowl o othrs Nw timstmp or riv mss: Compr ll mthin sts o pross IDs: st to hihst o vlus Any non-mth <P, T> sts t to th timstmp For hppn-or rltion: At lst on st o pross IDs must ommon to oth timstmps Mth ll orrsponin <P, T> sts: A:<P i, T >, B:<P i, T > I T T or ll ommon prosss P, thn A B Vtor Clos Summry Vtor los iv us wy o intiyin whih vnts r uslly rlt W r urnt to t th squnin orrt But Th siz o th vtor inrss with mor tors n th ntir vtor must stor with th t. Comprison ts mor tim thn omprin two numrs Wht i msss r onurrnt? App will hv to i how to hnl onlits 3 32 Summry: Loil Clos & Prtil Orrin Cuslity I thn vnt n t vnt Conurrny I nithr nor thn on vnt nnot t th othr Th n Prtil Orrin Cusl vnts r squn Totl Orrin All vnts r squn Pul Krzyznowsi 6