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runtime: only clear pointer-containing memory during map delete

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When deleting entries from a map, only clear the key and value
if they contain pointers. And use memclrHasPointers to do so.

While we're here, specialize key clearing in mapdelete_faststr,
and fix another missed usage of add in mapdelete.

Benchmarking impeded by #21546.

Change-Id: I3f6f924f738d6b899b722d6438e9e63f52359b84
Reviewed-on: https://go-review.googlesource.com/57630
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 2017-08-21 11:00:31 -07:00
parent 29e6bdc69c
commit 0c7fd56951
2 changed files with 35 additions and 16 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

18
src/runtime/hashmap.go
View File

@ -681,16 +681,20 @@ func mapdelete(t *maptype, h *hmap, key unsafe.Pointer) {
if !alg.equal(key, k2) {
continue
}
// Only clear key if there are pointers in it.
if t.indirectkey {
*(*unsafe.Pointer)(k) = nil
} else {
typedmemclr(t.key, k)
} else if t.key.kind&kindNoPointers == 0 {
memclrHasPointers(k, t.key.size)
}
v := unsafe.Pointer(uintptr(unsafe.Pointer(b)) + dataOffset + bucketCnt*uintptr(t.keysize) + i*uintptr(t.valuesize))
if t.indirectvalue {
*(*unsafe.Pointer)(v) = nil
} else {
typedmemclr(t.elem, v)
// Only clear value if there are pointers in it.
if t.indirectvalue || t.elem.kind&kindNoPointers == 0 {
v := add(unsafe.Pointer(b), dataOffset+bucketCnt*uintptr(t.keysize)+i*uintptr(t.valuesize))
if t.indirectvalue {
*(*unsafe.Pointer)(v) = nil
} else {
memclrHasPointers(v, t.elem.size)
}
}
b.tophash[i] = empty
h.count--

33
src/runtime/hashmap_fast.go
View File

@ -652,9 +652,15 @@ func mapdelete_fast32(t *maptype, h *hmap, key uint32) {
if key != *(*uint32)(k) || b.tophash[i] == empty {
continue
}
typedmemclr(t.key, unsafe.Pointer(k))
v := unsafe.Pointer(uintptr(unsafe.Pointer(b)) + dataOffset + bucketCnt*4 + i*uintptr(t.valuesize))
typedmemclr(t.elem, v)
// Only clear key if there are pointers in it.
if t.key.kind&kindNoPointers == 0 {
memclrHasPointers(k, t.key.size)
}
// Only clear value if there are pointers in it.
if t.elem.kind&kindNoPointers == 0 {
v := unsafe.Pointer(uintptr(unsafe.Pointer(b)) + dataOffset + bucketCnt*4 + i*uintptr(t.valuesize))
memclrHasPointers(v, t.elem.size)
}
b.tophash[i] = empty
h.count--
goto done
@ -699,9 +705,15 @@ func mapdelete_fast64(t *maptype, h *hmap, key uint64) {
if key != *(*uint64)(k) || b.tophash[i] == empty {
continue
}
typedmemclr(t.key, unsafe.Pointer(k))
v := unsafe.Pointer(uintptr(unsafe.Pointer(b)) + dataOffset + bucketCnt*8 + i*uintptr(t.valuesize))
typedmemclr(t.elem, v)
// Only clear key if there are pointers in it.
if t.key.kind&kindNoPointers == 0 {
memclrHasPointers(k, t.key.size)
}
// Only clear value if there are pointers in it.
if t.elem.kind&kindNoPointers == 0 {
v := unsafe.Pointer(uintptr(unsafe.Pointer(b)) + dataOffset + bucketCnt*8 + i*uintptr(t.valuesize))
memclrHasPointers(v, t.elem.size)
}
b.tophash[i] = empty
h.count--
goto done
@ -752,9 +764,12 @@ func mapdelete_faststr(t *maptype, h *hmap, ky string) {
if k.str != key.str && !memequal(k.str, key.str, uintptr(key.len)) {
continue
}
typedmemclr(t.key, unsafe.Pointer(k))
v := unsafe.Pointer(uintptr(unsafe.Pointer(b)) + dataOffset + bucketCnt*2*sys.PtrSize + i*uintptr(t.valuesize))
typedmemclr(t.elem, v)
*(*string)(kptr) = ""
// Only clear value if there are pointers in it.
if t.elem.kind&kindNoPointers == 0 {
v := unsafe.Pointer(uintptr(unsafe.Pointer(b)) + dataOffset + bucketCnt*2*sys.PtrSize + i*uintptr(t.valuesize))
memclrHasPointers(v, t.elem.size)
}
b.tophash[i] = empty
h.count--
goto done