tattempt better flushing ' - plan9port - [fork] Plan 9 from user space
(HTM) git clone git://src.adamsgaard.dk/plan9port
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---
(DIR) commit 59a9682013a2f4c5ee679ba910fe234ea61f6808
(DIR) parent eacc220a040de32a873340274f09b8e0498ff85f
(HTM) Author: rsc <devnull@localhost>
Date: Thu, 17 Jun 2004 21:13:51 +0000
attempt better flushing
'
Diffstat:
M src/libventi/file.c | 49 +++++++++++++++++++------------
1 file changed, 31 insertions(+), 18 deletions(-)
---
(DIR) diff --git a/src/libventi/file.c b/src/libventi/file.c
t@@ -664,7 +664,7 @@ mkindices(VtEntry *e, u32int bn, int *index)
{
int i, np;
- memset(index, 0, VtPointerDepth*sizeof(int));
+ memset(index, 0, (VtPointerDepth+1)*sizeof(int));
np = e->psize/VtScoreSize;
for(i=0; bn > 0; i++){
t@@ -1168,8 +1168,8 @@ vtfileflushbefore(VtFile *r, u64int offset)
{
VtBlock *b, *bb;
VtEntry e;
- int i, base, depth, ppb, epb, ok;
- int index[VtPointerDepth+1], index1[VtPointerDepth+1], j, ret;
+ int i, base, depth, ppb, epb, doflush;
+ int index[VtPointerDepth+1], j, ret;
VtBlock *bi[VtPointerDepth+2];
uchar *score;
t@@ -1181,6 +1181,9 @@ vtfileflushbefore(VtFile *r, u64int offset)
if(b == nil)
return -1;
+ /*
+ * compute path through tree for the last written byte and the next one.
+ */
ret = -1;
memset(bi, 0, sizeof bi);
depth = DEPTH(e.type);
t@@ -1190,10 +1193,12 @@ vtfileflushbefore(VtFile *r, u64int offset)
goto Err;
if(i > depth)
goto Err;
- mkindices(&e, offset/e.dsize, index1);
ppb = e.psize / VtScoreSize;
epb = e.dsize / VtEntrySize;
+ /*
+ * load the blocks along the last written byte
+ */
index[depth] = r->offset % r->epb;
for(i=depth; i>=0; i--){
bb = blockwalk(b, index[i], r->c, VtORDWR, &e);
t@@ -1204,33 +1209,41 @@ vtfileflushbefore(VtFile *r, u64int offset)
}
ret = 0;
+ /*
+ * walk up the path from leaf to root, flushing anything that
+ * has been finished.
+ */
base = e.type&~VtTypeDepthMask;
for(i=0; i<depth; i++){
+ doflush = 0;
if(i == 0){
- /* bottom: data or dir block */
- ok = offset%e.dsize == 0;
+ /* leaf: data or dir block */
+ if(offset%e.dsize == 0)
+ doflush = 1;
}else{
- /* middle: pointer blocks */
+ /*
+ * interior node: pointer blocks.
+ * specifically, b = bi[i] is a block whose index[i-1]'th entry
+ * points at bi[i-1].
+ */
b = bi[i];
+
/*
- * flush everything up to the break
+ * the index entries up to but not including index[i-1] point at
+ * finished blocks, so flush them for sure.
*/
for(j=0; j<index[i-1]; j++)
if(flushblock(r->c, nil, b->data+j*VtScoreSize, ppb, epb, base+i-1) < 0)
goto Err;
+
/*
- * if the rest of the block is already flushed,
- * we can flush the whole block.
+ * if index[i-1] is the last entry in the block and is global
+ * (i.e. the kid is flushed), then we can flush this block.
*/
- ok = 0;
- if(index[i] != index1[i]){
- ok = 1;
- for(; j<ppb; j++)
- if(vtglobaltolocal(b->data+j*VtScoreSize) != NilBlock)
- ok = 0;
- }
+ if(j==ppb-1 && vtglobaltolocal(b->data+j*VtScoreSize)==NilBlock)
+ doflush = 1;
}
- if(ok){
+ if(doflush){
if(i == depth)
score = e.score;
else