Changeset: ba14c1199e06 for MonetDB
URL: https://dev.monetdb.org/hg/MonetDB?cmd=changeset;node=ba14c1199e06
Modified Files:
gdk/gdk_atoms.c
Branch: Jul2017
Log Message:
Only write into string heap if we actually change something.
This only matters if the heap was memory mapped, since then the OS
won't overwrite the file and update the modification time.
diffs (62 lines):
diff --git a/gdk/gdk_atoms.c b/gdk/gdk_atoms.c
--- a/gdk/gdk_atoms.c
+++ b/gdk/gdk_atoms.c
@@ -1150,19 +1150,15 @@ strHash(const char *s)
void
strCleanHash(Heap *h, int rebuild)
{
- char oldhash[GDK_STRHASHSIZE];
+ stridx_t newhash[GDK_STRHASHTABLE];
size_t pad, pos;
const size_t extralen = h->hashash ? EXTRALEN : 0;
- stridx_t *bucket;
BUN off, strhash;
const char *s;
(void) rebuild;
if (!h->cleanhash)
return;
- /* copy old hash table so we can check whether we changed it */
- memcpy(oldhash, h->base, sizeof(oldhash));
- h->cleanhash = 0;
/* rebuild hash table for double elimination
*
* If appending strings to the BAT was aborted, if the heap
@@ -1173,7 +1169,7 @@ strCleanHash(Heap *h, int rebuild)
* Note that we will only do this the first time the heap is
* loaded, and only for heaps that existed when the server was
* started. */
- memset(h->base, 0, GDK_STRHASHSIZE);
+ memset(newhash, 0, sizeof(newhash));
pos = GDK_STRHASHSIZE;
while (pos < h->free && pos < GDK_ELIMLIMIT) {
pad = GDK_VARALIGN - (pos & (GDK_VARALIGN - 1));
@@ -1186,8 +1182,7 @@ strCleanHash(Heap *h, int rebuild)
else
GDK_STRHASH(s, strhash);
off = strhash & GDK_STRHASHMASK;
- bucket = ((stridx_t *) h->base) + off;
- *bucket = (stridx_t) (pos - extralen - sizeof(stridx_t));
+ newhash[off] = (stridx_t) (pos - extralen - sizeof(stridx_t));
pos += GDK_STRLEN(s);
}
#ifndef NDEBUG
@@ -1205,13 +1200,14 @@ strCleanHash(Heap *h, int rebuild)
}
#endif
/* only set dirty flag if the hash table actually changed */
- if (!h->dirty &&
- memcmp(oldhash, h->base, sizeof(oldhash)) != 0) {
- if (h->storage == STORE_MMAP)
+ if (memcmp(newhash, h->base, sizeof(newhash)) != 0) {
+ memcpy(h->base, newhash, sizeof(newhash));
+ if (h->storage == STORE_MMAP) {
(void) MT_msync(h->base, GDK_STRHASHSIZE);
- else
+ } else
h->dirty = 1;
}
+ h->cleanhash = 0;
}
/*
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