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runtime: split advanceEvacuationMark from evacuate

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Minor refactoring. This is a step towards specializing evacuate
for mapfast key types.

Change-Id: Icffe2759b7d38e5c008d03941918d5a912ce62f6
Reviewed-on: https://go-review.googlesource.com/56933
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
This commit is contained in:
Josh Bleecher Snyder 2017-08-17 10:37:17 -07:00
parent 43d4c9f4f1
commit e0b34e7be7
1 changed files with 23 additions and 20 deletions
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43
src/runtime/hashmap.go
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@ -1138,29 +1138,32 @@ func evacuate(t *maptype, h *hmap, oldbucket uintptr) {
} }
} }
// Advance evacuation mark
if oldbucket == h.nevacuate { if oldbucket == h.nevacuate {
advanceEvacuationMark(h, t, newbit)
}
}
func advanceEvacuationMark(h *hmap, t *maptype, newbit uintptr) {
h.nevacuate++
// Experiments suggest that 1024 is overkill by at least an order of magnitude.
// Put it in there as a safeguard anyway, to ensure O(1) behavior.
stop := h.nevacuate + 1024
if stop > newbit {
stop = newbit
}
for h.nevacuate != stop && bucketEvacuated(t, h, h.nevacuate) {
h.nevacuate++ h.nevacuate++
// Experiments suggest that 1024 is overkill by at least an order of magnitude. }
// Put it in there as a safeguard anyway, to ensure O(1) behavior. if h.nevacuate == newbit { // newbit == # of oldbuckets
stop := h.nevacuate + 1024 // Growing is all done. Free old main bucket array.
if stop > newbit { h.oldbuckets = nil
stop = newbit // Can discard old overflow buckets as well.
} // If they are still referenced by an iterator,
for h.nevacuate != stop && bucketEvacuated(t, h, h.nevacuate) { // then the iterator holds a pointers to the slice.
h.nevacuate++ if h.extra != nil {
} h.extra.overflow[1] = nil
if h.nevacuate == newbit { // newbit == # of oldbuckets
// Growing is all done. Free old main bucket array.
h.oldbuckets = nil
// Can discard old overflow buckets as well.
// If they are still referenced by an iterator,
// then the iterator holds a pointers to the slice.
if h.extra != nil {
h.extra.overflow[1] = nil
}
h.flags &^= sameSizeGrow
} }
h.flags &^= sameSizeGrow
} }
} }