484 lines
14 KiB
Go
484 lines
14 KiB
Go
// Copyright 2018 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package runtime
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import (
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"runtime/internal/sys"
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"unsafe"
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)
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// For gccgo, use go:linkname to export compiler-called functions.
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//
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//go:linkname mapaccess1_faststr
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//go:linkname mapaccess2_faststr
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//go:linkname mapassign_faststr
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//go:linkname mapdelete_faststr
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func mapaccess1_faststr(t *maptype, h *hmap, ky string) unsafe.Pointer {
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if raceenabled && h != nil {
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callerpc := getcallerpc()
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racereadpc(unsafe.Pointer(h), callerpc, funcPC(mapaccess1_faststr))
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}
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if h == nil || h.count == 0 {
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return unsafe.Pointer(&zeroVal[0])
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}
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if h.flags&hashWriting != 0 {
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throw("concurrent map read and map write")
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}
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key := stringStructOf(&ky)
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if h.B == 0 {
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// One-bucket table.
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b := (*bmap)(h.buckets)
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if key.len < 32 {
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// short key, doing lots of comparisons is ok
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for i, kptr := uintptr(0), b.keys(); i < bucketCnt; i, kptr = i+1, add(kptr, 2*sys.PtrSize) {
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k := (*stringStruct)(kptr)
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if k.len != key.len || isEmpty(b.tophash[i]) {
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if b.tophash[i] == emptyRest {
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break
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}
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continue
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}
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if k.str == key.str || memequal(k.str, key.str, uintptr(key.len)) {
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return add(unsafe.Pointer(b), dataOffset+bucketCnt*2*sys.PtrSize+i*uintptr(t.elemsize))
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}
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}
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return unsafe.Pointer(&zeroVal[0])
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}
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// long key, try not to do more comparisons than necessary
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keymaybe := uintptr(bucketCnt)
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for i, kptr := uintptr(0), b.keys(); i < bucketCnt; i, kptr = i+1, add(kptr, 2*sys.PtrSize) {
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k := (*stringStruct)(kptr)
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if k.len != key.len || isEmpty(b.tophash[i]) {
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if b.tophash[i] == emptyRest {
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break
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}
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continue
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}
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if k.str == key.str {
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return add(unsafe.Pointer(b), dataOffset+bucketCnt*2*sys.PtrSize+i*uintptr(t.elemsize))
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}
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// check first 4 bytes
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if *((*[4]byte)(key.str)) != *((*[4]byte)(k.str)) {
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continue
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}
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// check last 4 bytes
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if *((*[4]byte)(add(key.str, uintptr(key.len)-4))) != *((*[4]byte)(add(k.str, uintptr(key.len)-4))) {
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continue
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}
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if keymaybe != bucketCnt {
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// Two keys are potential matches. Use hash to distinguish them.
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goto dohash
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}
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keymaybe = i
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}
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if keymaybe != bucketCnt {
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k := (*stringStruct)(add(unsafe.Pointer(b), dataOffset+keymaybe*2*sys.PtrSize))
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if memequal(k.str, key.str, uintptr(key.len)) {
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return add(unsafe.Pointer(b), dataOffset+bucketCnt*2*sys.PtrSize+keymaybe*uintptr(t.elemsize))
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}
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}
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return unsafe.Pointer(&zeroVal[0])
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}
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dohash:
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hash := t.key.hashfn(noescape(unsafe.Pointer(&ky)), uintptr(h.hash0))
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m := bucketMask(h.B)
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b := (*bmap)(add(h.buckets, (hash&m)*uintptr(t.bucketsize)))
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if c := h.oldbuckets; c != nil {
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if !h.sameSizeGrow() {
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// There used to be half as many buckets; mask down one more power of two.
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m >>= 1
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}
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oldb := (*bmap)(add(c, (hash&m)*uintptr(t.bucketsize)))
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if !evacuated(oldb) {
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b = oldb
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}
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}
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top := tophash(hash)
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for ; b != nil; b = b.overflow(t) {
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for i, kptr := uintptr(0), b.keys(); i < bucketCnt; i, kptr = i+1, add(kptr, 2*sys.PtrSize) {
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k := (*stringStruct)(kptr)
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if k.len != key.len || b.tophash[i] != top {
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continue
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}
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if k.str == key.str || memequal(k.str, key.str, uintptr(key.len)) {
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return add(unsafe.Pointer(b), dataOffset+bucketCnt*2*sys.PtrSize+i*uintptr(t.elemsize))
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}
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}
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}
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return unsafe.Pointer(&zeroVal[0])
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}
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func mapaccess2_faststr(t *maptype, h *hmap, ky string) (unsafe.Pointer, bool) {
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if raceenabled && h != nil {
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callerpc := getcallerpc()
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racereadpc(unsafe.Pointer(h), callerpc, funcPC(mapaccess2_faststr))
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}
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if h == nil || h.count == 0 {
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return unsafe.Pointer(&zeroVal[0]), false
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}
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if h.flags&hashWriting != 0 {
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throw("concurrent map read and map write")
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}
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key := stringStructOf(&ky)
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if h.B == 0 {
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// One-bucket table.
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b := (*bmap)(h.buckets)
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if key.len < 32 {
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// short key, doing lots of comparisons is ok
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for i, kptr := uintptr(0), b.keys(); i < bucketCnt; i, kptr = i+1, add(kptr, 2*sys.PtrSize) {
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k := (*stringStruct)(kptr)
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if k.len != key.len || isEmpty(b.tophash[i]) {
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if b.tophash[i] == emptyRest {
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break
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}
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continue
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}
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if k.str == key.str || memequal(k.str, key.str, uintptr(key.len)) {
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return add(unsafe.Pointer(b), dataOffset+bucketCnt*2*sys.PtrSize+i*uintptr(t.elemsize)), true
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}
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}
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return unsafe.Pointer(&zeroVal[0]), false
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}
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// long key, try not to do more comparisons than necessary
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keymaybe := uintptr(bucketCnt)
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for i, kptr := uintptr(0), b.keys(); i < bucketCnt; i, kptr = i+1, add(kptr, 2*sys.PtrSize) {
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k := (*stringStruct)(kptr)
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if k.len != key.len || isEmpty(b.tophash[i]) {
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if b.tophash[i] == emptyRest {
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break
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}
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continue
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}
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if k.str == key.str {
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return add(unsafe.Pointer(b), dataOffset+bucketCnt*2*sys.PtrSize+i*uintptr(t.elemsize)), true
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}
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// check first 4 bytes
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if *((*[4]byte)(key.str)) != *((*[4]byte)(k.str)) {
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continue
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}
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// check last 4 bytes
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if *((*[4]byte)(add(key.str, uintptr(key.len)-4))) != *((*[4]byte)(add(k.str, uintptr(key.len)-4))) {
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continue
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}
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if keymaybe != bucketCnt {
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// Two keys are potential matches. Use hash to distinguish them.
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goto dohash
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}
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keymaybe = i
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}
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if keymaybe != bucketCnt {
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k := (*stringStruct)(add(unsafe.Pointer(b), dataOffset+keymaybe*2*sys.PtrSize))
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if memequal(k.str, key.str, uintptr(key.len)) {
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return add(unsafe.Pointer(b), dataOffset+bucketCnt*2*sys.PtrSize+keymaybe*uintptr(t.elemsize)), true
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}
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}
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return unsafe.Pointer(&zeroVal[0]), false
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}
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dohash:
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hash := t.key.hashfn(noescape(unsafe.Pointer(&ky)), uintptr(h.hash0))
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m := bucketMask(h.B)
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b := (*bmap)(add(h.buckets, (hash&m)*uintptr(t.bucketsize)))
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if c := h.oldbuckets; c != nil {
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if !h.sameSizeGrow() {
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// There used to be half as many buckets; mask down one more power of two.
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m >>= 1
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}
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oldb := (*bmap)(add(c, (hash&m)*uintptr(t.bucketsize)))
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if !evacuated(oldb) {
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b = oldb
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}
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}
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top := tophash(hash)
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for ; b != nil; b = b.overflow(t) {
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for i, kptr := uintptr(0), b.keys(); i < bucketCnt; i, kptr = i+1, add(kptr, 2*sys.PtrSize) {
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k := (*stringStruct)(kptr)
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if k.len != key.len || b.tophash[i] != top {
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continue
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}
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if k.str == key.str || memequal(k.str, key.str, uintptr(key.len)) {
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return add(unsafe.Pointer(b), dataOffset+bucketCnt*2*sys.PtrSize+i*uintptr(t.elemsize)), true
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}
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}
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}
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return unsafe.Pointer(&zeroVal[0]), false
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}
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func mapassign_faststr(t *maptype, h *hmap, s string) unsafe.Pointer {
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if h == nil {
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panic(plainError("assignment to entry in nil map"))
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}
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if raceenabled {
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callerpc := getcallerpc()
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racewritepc(unsafe.Pointer(h), callerpc, funcPC(mapassign_faststr))
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}
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if h.flags&hashWriting != 0 {
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throw("concurrent map writes")
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}
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key := stringStructOf(&s)
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hash := t.key.hashfn(noescape(unsafe.Pointer(&s)), uintptr(h.hash0))
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// Set hashWriting after calling alg.hash for consistency with mapassign.
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h.flags ^= hashWriting
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if h.buckets == nil {
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h.buckets = newobject(t.bucket) // newarray(t.bucket, 1)
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}
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again:
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bucket := hash & bucketMask(h.B)
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if h.growing() {
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growWork_faststr(t, h, bucket)
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}
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b := (*bmap)(unsafe.Pointer(uintptr(h.buckets) + bucket*uintptr(t.bucketsize)))
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top := tophash(hash)
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var insertb *bmap
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var inserti uintptr
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var insertk unsafe.Pointer
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bucketloop:
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for {
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for i := uintptr(0); i < bucketCnt; i++ {
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if b.tophash[i] != top {
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if isEmpty(b.tophash[i]) && insertb == nil {
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insertb = b
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inserti = i
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}
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if b.tophash[i] == emptyRest {
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break bucketloop
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}
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continue
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}
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k := (*stringStruct)(add(unsafe.Pointer(b), dataOffset+i*2*sys.PtrSize))
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if k.len != key.len {
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continue
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}
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if k.str != key.str && !memequal(k.str, key.str, uintptr(key.len)) {
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continue
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}
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// already have a mapping for key. Update it.
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inserti = i
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insertb = b
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goto done
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}
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ovf := b.overflow(t)
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if ovf == nil {
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break
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}
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b = ovf
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}
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// Did not find mapping for key. Allocate new cell & add entry.
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// If we hit the max load factor or we have too many overflow buckets,
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// and we're not already in the middle of growing, start growing.
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if !h.growing() && (overLoadFactor(h.count+1, h.B) || tooManyOverflowBuckets(h.noverflow, h.B)) {
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hashGrow(t, h)
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goto again // Growing the table invalidates everything, so try again
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}
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if insertb == nil {
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// all current buckets are full, allocate a new one.
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insertb = h.newoverflow(t, b)
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inserti = 0 // not necessary, but avoids needlessly spilling inserti
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}
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insertb.tophash[inserti&(bucketCnt-1)] = top // mask inserti to avoid bounds checks
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insertk = add(unsafe.Pointer(insertb), dataOffset+inserti*2*sys.PtrSize)
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// store new key at insert position
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*((*stringStruct)(insertk)) = *key
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h.count++
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done:
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elem := add(unsafe.Pointer(insertb), dataOffset+bucketCnt*2*sys.PtrSize+inserti*uintptr(t.elemsize))
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if h.flags&hashWriting == 0 {
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throw("concurrent map writes")
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}
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h.flags &^= hashWriting
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return elem
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}
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func mapdelete_faststr(t *maptype, h *hmap, ky string) {
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if raceenabled && h != nil {
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callerpc := getcallerpc()
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racewritepc(unsafe.Pointer(h), callerpc, funcPC(mapdelete_faststr))
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}
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if h == nil || h.count == 0 {
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return
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}
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if h.flags&hashWriting != 0 {
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throw("concurrent map writes")
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}
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key := stringStructOf(&ky)
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hash := t.key.hashfn(noescape(unsafe.Pointer(&ky)), uintptr(h.hash0))
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// Set hashWriting after calling alg.hash for consistency with mapdelete
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h.flags ^= hashWriting
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bucket := hash & bucketMask(h.B)
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if h.growing() {
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growWork_faststr(t, h, bucket)
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}
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b := (*bmap)(add(h.buckets, bucket*uintptr(t.bucketsize)))
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bOrig := b
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top := tophash(hash)
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search:
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for ; b != nil; b = b.overflow(t) {
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for i, kptr := uintptr(0), b.keys(); i < bucketCnt; i, kptr = i+1, add(kptr, 2*sys.PtrSize) {
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k := (*stringStruct)(kptr)
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if k.len != key.len || b.tophash[i] != top {
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continue
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}
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if k.str != key.str && !memequal(k.str, key.str, uintptr(key.len)) {
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continue
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}
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// Clear key's pointer.
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k.str = nil
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e := add(unsafe.Pointer(b), dataOffset+bucketCnt*2*sys.PtrSize+i*uintptr(t.elemsize))
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if t.elem.ptrdata != 0 {
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memclrHasPointers(e, t.elem.size)
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} else {
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memclrNoHeapPointers(e, t.elem.size)
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}
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b.tophash[i] = emptyOne
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// If the bucket now ends in a bunch of emptyOne states,
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// change those to emptyRest states.
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if i == bucketCnt-1 {
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if b.overflow(t) != nil && b.overflow(t).tophash[0] != emptyRest {
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goto notLast
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}
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} else {
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if b.tophash[i+1] != emptyRest {
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goto notLast
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}
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}
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for {
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b.tophash[i] = emptyRest
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if i == 0 {
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if b == bOrig {
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break // beginning of initial bucket, we're done.
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}
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// Find previous bucket, continue at its last entry.
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c := b
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for b = bOrig; b.overflow(t) != c; b = b.overflow(t) {
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}
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i = bucketCnt - 1
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} else {
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i--
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}
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if b.tophash[i] != emptyOne {
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break
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}
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}
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notLast:
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h.count--
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break search
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}
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}
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if h.flags&hashWriting == 0 {
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throw("concurrent map writes")
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}
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h.flags &^= hashWriting
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}
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func growWork_faststr(t *maptype, h *hmap, bucket uintptr) {
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// make sure we evacuate the oldbucket corresponding
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// to the bucket we're about to use
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evacuate_faststr(t, h, bucket&h.oldbucketmask())
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// evacuate one more oldbucket to make progress on growing
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if h.growing() {
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evacuate_faststr(t, h, h.nevacuate)
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}
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}
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func evacuate_faststr(t *maptype, h *hmap, oldbucket uintptr) {
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b := (*bmap)(add(h.oldbuckets, oldbucket*uintptr(t.bucketsize)))
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newbit := h.noldbuckets()
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if !evacuated(b) {
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// TODO: reuse overflow buckets instead of using new ones, if there
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// is no iterator using the old buckets. (If !oldIterator.)
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// xy contains the x and y (low and high) evacuation destinations.
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var xy [2]evacDst
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x := &xy[0]
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x.b = (*bmap)(add(h.buckets, oldbucket*uintptr(t.bucketsize)))
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x.k = add(unsafe.Pointer(x.b), dataOffset)
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x.e = add(x.k, bucketCnt*2*sys.PtrSize)
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if !h.sameSizeGrow() {
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// Only calculate y pointers if we're growing bigger.
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// Otherwise GC can see bad pointers.
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y := &xy[1]
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y.b = (*bmap)(add(h.buckets, (oldbucket+newbit)*uintptr(t.bucketsize)))
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y.k = add(unsafe.Pointer(y.b), dataOffset)
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y.e = add(y.k, bucketCnt*2*sys.PtrSize)
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}
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for ; b != nil; b = b.overflow(t) {
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k := add(unsafe.Pointer(b), dataOffset)
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e := add(k, bucketCnt*2*sys.PtrSize)
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for i := 0; i < bucketCnt; i, k, e = i+1, add(k, 2*sys.PtrSize), add(e, uintptr(t.elemsize)) {
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top := b.tophash[i]
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if isEmpty(top) {
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b.tophash[i] = evacuatedEmpty
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continue
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}
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if top < minTopHash {
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throw("bad map state")
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}
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var useY uint8
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if !h.sameSizeGrow() {
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// Compute hash to make our evacuation decision (whether we need
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// to send this key/elem to bucket x or bucket y).
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hash := t.key.hashfn(k, uintptr(h.hash0))
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if hash&newbit != 0 {
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useY = 1
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}
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}
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b.tophash[i] = evacuatedX + useY // evacuatedX + 1 == evacuatedY, enforced in makemap
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dst := &xy[useY] // evacuation destination
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if dst.i == bucketCnt {
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dst.b = h.newoverflow(t, dst.b)
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dst.i = 0
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dst.k = add(unsafe.Pointer(dst.b), dataOffset)
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dst.e = add(dst.k, bucketCnt*2*sys.PtrSize)
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}
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dst.b.tophash[dst.i&(bucketCnt-1)] = top // mask dst.i as an optimization, to avoid a bounds check
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// Copy key.
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*(*string)(dst.k) = *(*string)(k)
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typedmemmove(t.elem, dst.e, e)
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dst.i++
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// These updates might push these pointers past the end of the
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// key or elem arrays. That's ok, as we have the overflow pointer
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// at the end of the bucket to protect against pointing past the
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// end of the bucket.
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dst.k = add(dst.k, 2*sys.PtrSize)
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dst.e = add(dst.e, uintptr(t.elemsize))
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}
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}
|
|
// Unlink the overflow buckets & clear key/elem to help GC.
|
|
if h.flags&oldIterator == 0 && t.bucket.ptrdata != 0 {
|
|
b := add(h.oldbuckets, oldbucket*uintptr(t.bucketsize))
|
|
// Preserve b.tophash because the evacuation
|
|
// state is maintained there.
|
|
ptr := add(b, dataOffset)
|
|
n := uintptr(t.bucketsize) - dataOffset
|
|
memclrHasPointers(ptr, n)
|
|
}
|
|
}
|
|
|
|
if oldbucket == h.nevacuate {
|
|
advanceEvacuationMark(h, t, newbit)
|
|
}
|
|
}
|