ref: a411870ee4640241e3c494367d922847da84f972
dir: purgatorio/appl/lib/styxpersist.b
implement Styxpersist;
#
# Copyright © 2004 Vita Nuova Holdings Limited
#
include "sys.m";
sys: Sys;
include "draw.m";
include "styx.m";
styx: Styx;
Tmsg, Rmsg, NOFID, NOTAG: import styx;
include "rand.m";
rand: Rand;
include "factotum.m";
factotum: Factotum;
include "styxpersist.m";
NOTOPEN, DEAD, AUTH, OPEN: con iota;
NTAGHASH: con 32;
MAXBACKOFF: con 30*1000;
Estale: con "unable to reopen file";
Ebadtag: con "bad tag";
Epartial: con "operation possibly not completed";
Etypemismatch: con "tag type mismatch";
Debug: con 0;
Noqid: con Sys->Qid(big 0, 0, 0);
Nprocs: con 1;
Erroronpartial: con 1;
Table: adt[T] {
items: array of list of (int, T);
nilval: T;
new: fn(nslots: int, nilval: T): ref Table[T];
add: fn(t: self ref Table, id: int, x: T): int;
del: fn(t: self ref Table, id: int): int;
find: fn(t: self ref Table, id: int): T;
};
Fid: adt {
fid: int;
state: int;
omode: int;
qid: Sys->Qid;
uname: string;
aname: string;
authed: int;
path: list of string; # in reverse order.
};
Tag: adt {
m: ref Tmsg;
seq: int;
dead: int;
next: cyclic ref Tag;
};
Root: adt {
refcount: int;
attached: chan of int; # [1]; holds attached status: -1 (can't), 0 (haven't), 1 (attached)
fid: int;
qid: Sys->Qid;
uname: string;
aname: string;
};
keyspec: string;
tags := array[NTAGHASH] of ref Tag;
fids: ref Table[ref Fid];
ntags := 0;
seqno := 0;
doneversion := 0;
msize := 0;
ver: string;
cfd, sfd: ref Sys->FD;
tmsg: chan of ref Tmsg; # t-messages received from client
rmsg: chan of ref Rmsg; # r-messages received from server.
rmsgpid := -1;
token: chan of (int, chan of (ref Fid, ref Root)); # [Nprocs] of (procid, workchan)
procrmsg: array of chan of ref Rmsg;
init(clientfd: ref Sys->FD, usefac: int, kspec: string): (chan of chan of ref Sys->FD, string)
{
sys = load Sys Sys->PATH;
styx = load Styx Styx->PATH;
if(styx == nil)
return (nil, sys->sprint("cannot load %q: %r", Styx->PATH));
styx->init();
rand = load Rand Rand->PATH;
if (rand == nil)
return (nil, sys->sprint("cannot load %q: %r", Rand->PATH));
rand->init(sys->millisec());
if(usefac){
factotum = load Factotum Factotum->PATH;
if(factotum == nil)
return (nil, sys->sprint("cannot load %q: %r", Rand->PATH));
factotum->init();
}
keyspec = kspec;
connectc := chan of chan of ref Sys->FD;
spawn styxpersistproc(clientfd, connectc);
return (connectc, nil);
}
styxpersistproc(clientfd: ref Sys->FD, connectc: chan of chan of ref Sys->FD)
{
fids = Table[ref Fid].new(11, nil);
rmsg = chan of ref Rmsg;
tmsg = chan of ref Tmsg;
cfd = clientfd;
spawn tmsgreader();
connect(connectc);
for(;;)alt{
m := <-tmsg =>
if(m == nil || tagof(m) == tagof(Tmsg.Readerror))
quit();
t := newtag(m);
if(t == nil){
sendrmsg(ref Rmsg.Error(m.tag, Ebadtag));
continue;
}
if((rm := handletmsg(t)) != nil){
sendrmsg(rm);
gettag(m.tag, 1);
}else{
# XXX could be quicker about this as we don't rewrite messages
sendtmsg(m);
}
m := <-rmsg =>
if(m == nil || tagof(m) == tagof(Tmsg.Readerror)){
if(Debug) sys->print("**************** reconnect {\n");
do{
connect(connectc);
} while(resurrectfids() == 0);
resurrecttags();
if(Debug) sys->print("************** done reconnect }\n");
continue;
}
t := gettag(m.tag, 1);
if(t == nil){
log(sys->sprint("unexpected tag %d, %s", m.tag, m.text()));
continue;
}
if((e := handlermsg(m, t.m)) != nil)
log(e);
else{
# XXX could be quicker about this as we don't rewrite messages
sendrmsg(m);
}
}
}
quit()
{
log("quitting...\n");
# XXX shutdown properly
exit;
}
log(s: string)
{
sys->fprint(sys->fildes(2), "styxpersist: %s\n", s);
}
handletmsg(t: ref Tag): ref Rmsg
{
fid := NOFID;
pick m := t.m {
Flush =>
if(gettag(m.oldtag, 0) == nil)
return ref Rmsg.Flush(m.tag);
* =>
fid = tmsgfid(m);
}
if(fid != NOFID){
f := getfid(fid);
if(f.state == DEAD){
if(tagof(t.m) == tagof(Tmsg.Clunk)){
fids.del(f.fid);
return ref Rmsg.Clunk(t.m.tag);
}
return ref Rmsg.Error(t.m.tag, Estale);
}
}
return nil;
}
handlermsg(rm: ref Rmsg, tm: ref Tmsg): string
{
if(tagof(rm) == tagof(Rmsg.Error) &&
tagof(tm) != tagof(Tmsg.Remove) &&
tagof(tm) != tagof(Tmsg.Clunk))
return nil;
if(tagof(rm) != tagof(Rmsg.Error) && rm.mtype() != tm.mtype()+1)
return "type mismatch, got "+rm.text()+", reply to "+tm.text();
pick m := tm {
Auth =>
fid := newfid(m.afid); # XXX should we be concerned about this failing?
fid.state = AUTH;
Attach =>
fid := newfid(m.fid);
fid.uname = m.uname;
fid.aname = m.aname;
if(m.afid != NOFID)
fid.authed = 1;
Walk =>
fid := getfid(m.fid);
qids: array of Sys->Qid;
n := 0;
pick r := rm {
Walk =>
qids = r.qids;
}
if(len qids != len m.names)
return nil;
if(m.fid != m.newfid){
newfid := newfid(m.newfid);
*newfid = *fid;
newfid.fid = m.newfid;
fid = newfid;
}
for(i := 0; i < len qids; i++){
if(m.names[i] == ".."){
if(fid.path != nil)
fid.path = tl fid.path;
}else{
fid.path = m.names[i] :: fid.path;
}
fid.qid = qids[i];
}
Open =>
fid := getfid(m.fid);
fid.state = OPEN;
fid.omode = m.mode;
pick r := rm {
Open =>
fid.qid = r.qid;
}
Create =>
fid := getfid(m.fid);
fid.state = OPEN;
fid.omode = m.mode;
pick r := rm {
Create =>
fid.qid = r.qid;
}
Clunk or
Remove =>
fids.del(m.fid);
Wstat =>
if(m.stat.name != nil){
fid := getfid(m.fid);
fid.path = m.stat.name :: tl fid.path;
}
}
return nil;
}
# connect to destination with exponential backoff, setting sfd.
connect(connectc: chan of chan of ref Sys->FD)
{
reply := chan of ref Sys->FD;
sfd = nil;
backoff := 0;
for(;;){
connectc <-= reply;
fd := <-reply;
if(fd != nil){
kill(rmsgpid, "kill");
sfd = fd;
sync := chan of int;
spawn rmsgreader(fd, sync);
rmsgpid = <-sync;
if(version() != -1)
return;
sfd = nil;
}
if(backoff == 0)
backoff = 1000 + rand->rand(500) - 250;
else if(backoff < MAXBACKOFF)
backoff = backoff * 3 / 2;
sys->sleep(backoff);
}
}
# first time we use the version offered by the client,
# and record it; subsequent times we offer the response
# recorded initially.
version(): int
{
if(doneversion)
sendtmsg(ref Tmsg.Version(NOTAG, msize, ver));
else{
m := <-tmsg;
if(m == nil)
quit();
if(m == nil || tagof(m) != tagof(Tmsg.Version)){
log("invalid initial version message: "+m.text());
quit();
}
sendtmsg(m);
}
if((gm := <-rmsg) == nil)
return -1;
pick m := gm {
Readerror =>
return -1;
Version =>
if(doneversion && (m.msize != msize || m.version != ver)){
log("wrong msize/version on reconnect");
# XXX is there any hope here - we could quit.
return -1;
}
if(!doneversion){
msize = m.msize;
ver = m.version;
doneversion = 1;
sendrmsg(m);
}
return 0;
* =>
log("invalid reply to Tversion: "+m.text());
return -1;
}
}
resurrecttags()
{
# make sure that we send the tmsgs in the same order that
# they were sent originally.
all := array[ntags] of ref Tag;
n := 0;
for(i := 0; i < len tags; i++){
for(t := tags[i]; t != nil; t = t.next){
fid := tmsgfid(t.m);
if(fid != NOFID && (f := getfid(fid)) != nil){
if(f.state == DEAD){
sendrmsg(ref Rmsg.Error(t.m.tag, Estale));
t.dead = 1;
continue;
}
if(Erroronpartial){
partial := 0;
pick m := t.m {
Create =>
partial = 1;
Remove =>
partial = 1;
Wstat =>
partial = (m.stat.name != nil && f.path != nil && hd f.path != m.stat.name);
Write =>
partial = (f.qid.qtype & Sys->QTAPPEND);
}
if(partial)
sendrmsg(ref Rmsg.Error(t.m.tag, Epartial));
}
}
all[n++] = t;
}
}
all = all[0:n];
sort(all);
for(i = 0; i < len all; i++){
t := all[i];
pick m := t.m {
Flush =>
ot := gettag(m.oldtag, 0);
if(ot == nil || ot.dead){
sendrmsg(ref Rmsg.Flush(t.m.tag));
t.dead = 1;
continue;
}
}
sendtmsg(t.m);
}
tags = array[len tags] of ref Tag;
ntags = 0;
for(i = 0; i < len all; i++)
if(all[i].dead == 0)
newtag(all[i].m);
}
# re-open all the old fids, if possible.
# use up to Nprocs processes to keep latency down.
resurrectfids(): int
{
procrmsg = array[Nprocs] of {* => chan[1] of ref Rmsg};
spawn rmsgmarshal(finish := chan of int);
getroot := chan of (int, string, string, chan of ref Root);
usedroot := chan of ref Root;
spawn fidproc(getroot, usedroot);
token = chan[Nprocs] of (int, chan of (ref Fid, ref Root));
for(i := 0; i < Nprocs; i++)
token <-= (i, nil);
for(i = 0; i < len fids.items; i++){
for(fl := fids.items[i]; fl != nil; fl = tl fl){
fid := (hd fl).t1;
(procid, workc) := <-token;
getroot <-= (1, fid.uname, fid.aname, reply := chan of ref Root);
root := <-reply;
if(workc == nil){
workc = chan of (ref Fid, ref Root);
spawn workproc(procid, workc, usedroot);
}
workc <-= (fid, root);
}
}
for(i = 0; i < Nprocs; i++){
(nil, workc) := <-token;
if(workc != nil)
workc <-= (nil, nil);
}
for(i = 0; i < Nprocs; i++){
getroot <-= (0, nil, nil, reply := chan of ref Root);
root := <-reply;
if(<-root.attached > 0)
clunk(0, root.fid);
}
usedroot <-= nil;
return <-finish;
}
workproc(procid: int, workc: chan of (ref Fid, ref Root), usedroot: chan of ref Root)
{
while(((fid, root) := <-workc).t0 != nil){
# mark fid as dead only if it's a genuine server error, not if
# the server has just hung up.
if((err := resurrectfid(procid, fid, root)) != nil && sfd != nil){
log(err);
fid.state = DEAD;
}
usedroot <-= root;
token <-= (procid, workc);
}
}
resurrectfid(procid: int, fid: ref Fid, root: ref Root): string
{
if(fid.state == AUTH)
return "auth fid discarded";
attached := <-root.attached;
if(attached == -1){
root.attached <-= -1;
return "root attach failed";
}
if(!attached || root.uname != fid.uname || root.aname != fid.aname){
if(attached)
clunk(procid, root.fid);
afid := NOFID;
if(fid.authed){
afid = fid.fid - 1; # see unusedfid()
if((err := auth(procid, afid, root.uname, root.aname)) != nil){
log(err);
afid = -1;
}
}
(err, qid) := attach(procid, root.fid, afid, fid.uname, fid.aname);
if(afid != NOFID)
clunk(procid, afid);
if(err != nil){
root.attached <-= -1;
return "attach failed: "+err;
}
root.uname = fid.uname;
root.aname = fid.aname;
root.qid = qid;
}
root.attached <-= 1;
(err, qid) := walk(procid, root.fid, fid.fid, fid.path, root.qid);
if(err != nil)
return err;
if(fid.state == OPEN && (err = openfid(procid, fid)) != nil){
clunk(procid, fid.fid);
return err;
}
return nil;
}
openfid(procid: int, fid: ref Fid): string
{
(err, qid) := open(procid, fid.fid, fid.omode);
if(err != nil)
return err;
if(qid.path != fid.qid.path || qid.qtype != fid.qid.qtype)
return "qid mismatch on reopen";
return nil;
}
# store up to Nprocs separate root fids and dole them out to those that want them.
fidproc(getroot: chan of (int, string, string, chan of ref Root), usedroot: chan of ref Root)
{
roots := array[Nprocs] of ref Root;
n := 0;
maxfid := -1;
for(;;)alt{
(match, uname, aname, reply) := <-getroot =>
for(i := 0; i < n; i++)
if(match && roots[i].uname == uname && roots[i].aname == aname)
break;
if(i == n)
for(i = 0; i < n; i++)
if(roots[i].refcount == 0)
break;
if(i == n){
maxfid = unusedfid(maxfid);
roots[n] = ref Root(0, chan[1] of int, maxfid, Noqid, uname, aname);
roots[n++].attached <-= 0;
}
roots[i].refcount++;
reply <-= roots[i];
r := <-usedroot =>
if(r == nil)
exit;
r.refcount--;
}
}
clunk(procid: int, fid: int)
{
pick m := fcall(ref Tmsg.Clunk(procid, fid)) {
Error =>
if(sfd != nil)
log("error on clunk: " + m.ename);
}
}
attach(procid, fid, afid: int, uname, aname: string): (string, Sys->Qid)
{
pick m := fcall(ref Tmsg.Attach(procid, fid, afid, uname, aname)) {
Attach =>
return (nil, m.qid);
Error =>
return (m.ename, Noqid);
}
return (nil, Noqid); # not reached
}
read(procid, fid: int, buf: array of byte): (int, string)
{
# XXX assume that offsets are ignored of auth fid reads/writes
pick m := fcall(ref Tmsg.Read(procid, fid, big 0, len buf)) {
Error =>
return (-1, m.ename);
Read =>
buf[0:] = m.data;
return (len m.data, nil);
}
return (-1, nil); # not reached
}
write(procid, fid: int, buf: array of byte): (int, string)
{
# XXX assume that offsets are ignored of auth fid reads/writes
pick m := fcall(ref Tmsg.Write(procid, fid, big 0, buf)) {
Error =>
sys->werrstr(m.ename);
return (-1, sys->sprint("%r"));
Write =>
return (m.count, nil);
}
return (-1, nil); # not reached
}
auth(procid, fid: int, uname, aname: string): string
{
if(factotum == nil)
return "no factotum available";
pick m := fcall(ref Tmsg.Auth(procid, fid, uname, aname)) {
Error =>
return m.ename;
}
readc := chan of (array of byte, chan of (int, string));
writec := chan of (array of byte, chan of (int, string));
done := chan of (ref Factotum->Authinfo, string);
spawn factotum->genproxy(readc, writec, done,
sys->open("/mnt/factotum/rpc", Sys->ORDWR),
"proto=p9any role=client "+keyspec);
for(;;)alt{
(buf, reply) := <-readc =>
reply <-= read(procid, fid, buf);
(buf, reply) := <-writec =>
reply <-= write(procid, fid, buf);
(authinfo, err) := <-done =>
if(authinfo == nil){
clunk(procid, fid);
return err;
}
# XXX check that authinfo.cuid == uname?
return nil;
}
}
# path is in reverse order; assume fid != newfid on entry.
walk(procid: int, fid, newfid: int, path: list of string, qid: Sys->Qid): (string, Sys->Qid)
{
names := array[len path] of string;
for(i := len names - 1; i >= 0; i--)
(names[i], path) = (hd path, tl path);
do{
w := names;
if(len w > Styx->MAXWELEM)
w = w[0:Styx->MAXWELEM];
names = names[len w:];
pick m := fcall(ref Tmsg.Walk(procid, fid, newfid, w)) {
Error =>
if(newfid == fid)
clunk(procid, newfid);
return ("walk error: "+m.ename, Noqid);
Walk =>
if(len m.qids != len w){
if(newfid == fid)
clunk(procid, newfid);
return ("walk: file not found", Noqid);
}
if(len m.qids > 0)
qid = m.qids[len m.qids - 1];
fid = newfid;
}
}while(len names > 0);
return (nil, qid);
}
open(procid: int, fid: int, mode: int): (string, Sys->Qid)
{
pick m := fcall(ref Tmsg.Open(procid, fid, mode)) {
Error =>
return ("open: "+m.ename, Noqid);
Open =>
return (nil, m.qid); # XXX what if iounit doesn't match the original?
}
return (nil, Noqid); # not reached
}
fcall(m: ref Tmsg): ref Rmsg
{
sendtmsg(m);
pick rm := <-procrmsg[m.tag] {
Readerror =>
procrmsg[m.tag] <-= rm;
return ref Rmsg.Error(rm.tag, rm.error);
Error =>
return rm;
* =>
if(rm.mtype() != m.mtype()+1)
return ref Rmsg.Error(m.tag, Etypemismatch);
return rm;
}
}
# find an unused fid (and make sure that the one before it is unused
# too, in case we want to use it for an auth fid);
unusedfid(maxfid: int): int
{
for(f := maxfid + 1; ; f++)
if(fids.find(f) == nil && fids.find(f+1) == nil)
return f + 1;
abort("no unused fids - i don't believe it");
return 0;
}
# XXX what about message length limitations?
sendtmsg(m: ref Tmsg)
{
if(Debug) sys->print("%s\n", m.text());
d := m.pack();
if(sys->write(sfd, d, len d) != len d)
log(sys->sprint("tmsg write failed: %r")); # XXX could signal to redial
}
sendrmsg(m: ref Rmsg)
{
d := m.pack();
if(sys->write(cfd, d, len d) != len d){
log(sys->sprint("rmsg write failed: %r"));
quit();
}
}
rmsgmarshal(finish: chan of int)
{
for(;;)alt{
finish <-= 1 =>
exit;
m := <-rmsg =>
if(m == nil || tagof(m) == tagof(Rmsg.Readerror)){
sfd = nil;
for(i := 0; i < Nprocs; i++)
procrmsg[i] <-= ref Rmsg.Readerror(NOTAG, "hung up");
finish <-= 0;
exit;
}
if(m.tag >= Nprocs){
log("invalid reply message");
break;
}
# XXX if the server replies with a tag that no-one's waiting for. we'll lock up.
# (but is it much of a concern, given no flushes, etc?)
procrmsg[m.tag] <-= m;
}
}
rmsgreader(fd: ref Sys->FD, sync: chan of int)
{
sync <-= sys->pctl(0, nil);
m: ref Rmsg;
do {
m = Rmsg.read(fd, msize);
if(Debug) sys->print("%s\n", m.text());
rmsg <-= m;
} while(m != nil && tagof(m) != tagof(Tmsg.Readerror));
}
tmsgreader()
{
m: ref Tmsg;
do{
m = Tmsg.read(cfd, msize);
tmsg <-= m;
} while(m != nil && tagof(m) != tagof(Tmsg.Readerror));
}
abort(s: string)
{
log(s);
raise "abort";
}
tmsgfid(t: ref Tmsg): int
{
fid := NOFID;
pick m := t {
Attach =>
fid = m.afid;
Walk =>
fid = m.fid;
Open =>
fid = m.fid;
Create =>
fid = m.fid;
Read =>
fid = m.fid;
Write =>
fid = m.fid;
Clunk or
Stat or
Remove =>
fid = m.fid;
Wstat =>
fid = m.fid;
}
return fid;
}
blankfid: Fid;
newfid(fid: int): ref Fid
{
f := ref blankfid;
f.fid = fid;
if(fids.add(fid, f) == 0){
abort("duplicate fid "+string fid);
}
return f;
}
getfid(fid: int): ref Fid
{
return fids.find(fid);
}
newtag(m: ref Tmsg): ref Tag
{
# XXX what happens if the client sends a duplicate tag?
t := ref Tag(m, seqno++, 0, nil);
slot := t.m.tag & (NTAGHASH - 1);
t.next = tags[slot];
tags[slot] = t;
ntags++;
return t;
}
gettag(tag: int, destroy: int): ref Tag
{
slot := tag & (NTAGHASH - 1);
prev: ref Tag;
for(t := tags[slot]; t != nil; t = t.next){
if(t.m.tag == tag)
break;
prev = t;
}
if(t == nil || !destroy)
return t;
if(prev == nil)
tags[slot] = t.next;
else
prev.next = t.next;
ntags--;
return t;
}
Table[T].new(nslots: int, nilval: T): ref Table[T]
{
if(nslots == 0)
nslots = 13;
return ref Table[T](array[nslots] of list of (int, T), nilval);
}
Table[T].add(t: self ref Table[T], id: int, x: T): int
{
slot := id % len t.items;
for(q := t.items[slot]; q != nil; q = tl q)
if((hd q).t0 == id)
return 0;
t.items[slot] = (id, x) :: t.items[slot];
return 1;
}
Table[T].del(t: self ref Table[T], id: int): int
{
slot := id % len t.items;
p: list of (int, T);
r := 0;
for(q := t.items[slot]; q != nil; q = tl q){
if((hd q).t0 == id){
p = joinip(p, tl q);
r = 1;
break;
}
p = hd q :: p;
}
t.items[slot] = p;
return r;
}
Table[T].find(t: self ref Table[T], id: int): T
{
for(p := t.items[id % len t.items]; p != nil; p = tl p)
if((hd p).t0 == id)
return (hd p).t1;
return t.nilval;
}
sort(a: array of ref Tag)
{
mergesort(a, array[len a] of ref Tag);
}
mergesort(a, b: array of ref Tag)
{
r := len a;
if (r > 1) {
m := (r-1)/2 + 1;
mergesort(a[0:m], b[0:m]);
mergesort(a[m:], b[m:]);
b[0:] = a;
for ((i, j, k) := (0, m, 0); i < m && j < r; k++) {
if (b[i].seq > b[j].seq)
a[k] = b[j++];
else
a[k] = b[i++];
}
if (i < m)
a[k:] = b[i:m];
else if (j < r)
a[k:] = b[j:r];
}
}
kill(pid: int, note: string): int
{
fd := sys->open("#p/"+string pid+"/ctl", Sys->OWRITE);
if(fd == nil || sys->fprint(fd, "%s", note) < 0)
return -1;
return 0;
}
# join x to y, leaving result in arbitrary order.
joinip[T](x, y: list of (int, T)): list of (int, T)
{
if(len x > len y)
(x, y) = (y, x);
for(; x != nil; x = tl x)
y = hd x :: y;
return y;
}