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runtime: de-duplicate coalescing code

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Currently the code surrounding coalescing is duplicated between merging
with the span before the span considered for coalescing and merging with
the span after. This change factors out the shared portions of these
codepaths into a local closure which acts as a helper.

Change-Id: I7919fbed3f9a833eafb324a21a4beaa81f2eaa91
Reviewed-on: https://go-review.googlesource.com/c/158077
Run-TryBot: Michael Knyszek <mknyszek@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Austin Clements <austin@google.com>
This commit is contained in:
Michael Anthony Knyszek 2019-01-15 23:48:57 +00:00 • committed by Austin Clements
parent 79ac638e41
commit 2f99e889f0
1 changed files with 25 additions and 25 deletions
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50
src/runtime/mheap.go
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@ -425,41 +425,41 @@ func (h *mheap) coalesce(s *mspan) {
needsScavenge := false needsScavenge := false
prescavenged := s.released() // number of bytes already scavenged. prescavenged := s.released() // number of bytes already scavenged.
// Coalesce with earlier, later spans. // merge is a helper which merges other into s, deletes references to other
if before := spanOf(s.base() - 1); before != nil && before.state == mSpanFree { // in heap metadata, and then discards it.
// Now adjust s. merge := func(other *mspan) {
s.startAddr = before.startAddr // Adjust s via base and npages.
s.npages += before.npages if other.startAddr < s.startAddr {
s.needzero |= before.needzero s.startAddr = other.startAddr
h.setSpan(before.base(), s) }
s.npages += other.npages
s.needzero |= other.needzero
// If before or s are scavenged, then we need to scavenge the final coalesced span. // If before or s are scavenged, then we need to scavenge the final coalesced span.
needsScavenge = needsScavenge || before.scavenged || s.scavenged needsScavenge = needsScavenge || other.scavenged || s.scavenged
prescavenged += before.released() prescavenged += other.released()
// The size is potentially changing so the treap needs to delete adjacent nodes and // The size is potentially changing so the treap needs to delete adjacent nodes and
// insert back as a combined node. // insert back as a combined node.
if before.scavenged { if other.scavenged {
h.scav.removeSpan(before) h.scav.removeSpan(other)
} else { } else {
h.free.removeSpan(before) h.free.removeSpan(other)
} }
before.state = mSpanDead other.state = mSpanDead
h.spanalloc.free(unsafe.Pointer(before)) h.spanalloc.free(unsafe.Pointer(other))
}
// Coalesce with earlier, later spans.
if before := spanOf(s.base() - 1); before != nil && before.state == mSpanFree {
merge(before)
h.setSpan(s.base(), s)
} }
// Now check to see if next (greater addresses) span is free and can be coalesced. // Now check to see if next (greater addresses) span is free and can be coalesced.
if after := spanOf(s.base() + s.npages*pageSize); after != nil && after.state == mSpanFree { if after := spanOf(s.base() + s.npages*pageSize); after != nil && after.state == mSpanFree {
s.npages += after.npages merge(after)
s.needzero |= after.needzero
h.setSpan(s.base()+s.npages*pageSize-1, s) h.setSpan(s.base()+s.npages*pageSize-1, s)
needsScavenge = needsScavenge || after.scavenged || s.scavenged
prescavenged += after.released()
if after.scavenged {
h.scav.removeSpan(after)
} else {
h.free.removeSpan(after)
}
after.state = mSpanDead
h.spanalloc.free(unsafe.Pointer(after))
} }
if needsScavenge { if needsScavenge {