Imbus/xv6-riscv-kernel
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i think this is a working concurrent logging scheme

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This commit is contained in:
Robert Morris 2014-08-28 05:57:47 -04:00
parent 71453f72f2
commit 48aa917403
5 changed files with 117 additions and 99 deletions
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21
log.c
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@ -52,6 +52,10 @@ struct log log;
static void recover_from_log(void);
static void commit();
// statistics, delete eventually XXX.
static int maxsize;
static int maxoutstanding;
void
initlog(void)
{
@ -131,10 +135,15 @@ begin_op(void)
while(1){
if(log.committing){
sleep(&log, &log.lock);
} else if(log.lh.n + (log.outstanding+1)*MAXOPBLOCKS > LOGSIZE){
// this op might exhaust log space; wait for commit.
sleep(&log, &log.lock);
} else {
// XXX wait (for a commit) if log is longish.
// need to reserve to avoid over-commit of log space.
log.outstanding += 1;
if(log.outstanding > maxoutstanding){
maxoutstanding = log.outstanding;
cprintf("%d outstanding\n", log.outstanding);
}
release(&log.lock);
break;
}
@ -155,6 +164,9 @@ end_op(void)
if(log.outstanding == 0){
do_commit = 1;
log.committing = 1;
} else {
// begin_op() may be waiting for log space.
wakeup(&log);
}
release(&log.lock);
@ -208,6 +220,11 @@ log_write(struct buf *b)
if (i == log.lh.n)
log.lh.n++;
b->flags |= B_DIRTY; // XXX prevent eviction
if(log.lh.n > maxsize){
maxsize = log.lh.n;
cprintf("log size %d/%d\n", log.lh.n, LOGSIZE);
}
}
//PAGEBREAK!