mirror of git://gcc.gnu.org/git/gcc.git
961 lines
28 KiB
Go
961 lines
28 KiB
Go
// Copyright 2014 The Go Authors. All rights reserved.
|
|
// Use of this source code is governed by a BSD-style
|
|
// license that can be found in the LICENSE file.
|
|
|
|
package runtime
|
|
|
|
// This file contains the implementation of Go's map type.
|
|
//
|
|
// A map is just a hash table. The data is arranged
|
|
// into an array of buckets. Each bucket contains up to
|
|
// 8 key/value pairs. The low-order bits of the hash are
|
|
// used to select a bucket. Each bucket contains a few
|
|
// high-order bits of each hash to distinguish the entries
|
|
// within a single bucket.
|
|
//
|
|
// If more than 8 keys hash to a bucket, we chain on
|
|
// extra buckets.
|
|
//
|
|
// When the hashtable grows, we allocate a new array
|
|
// of buckets twice as big. Buckets are incrementally
|
|
// copied from the old bucket array to the new bucket array.
|
|
//
|
|
// Map iterators walk through the array of buckets and
|
|
// return the keys in walk order (bucket #, then overflow
|
|
// chain order, then bucket index). To maintain iteration
|
|
// semantics, we never move keys within their bucket (if
|
|
// we did, keys might be returned 0 or 2 times). When
|
|
// growing the table, iterators remain iterating through the
|
|
// old table and must check the new table if the bucket
|
|
// they are iterating through has been moved ("evacuated")
|
|
// to the new table.
|
|
|
|
// Picking loadFactor: too large and we have lots of overflow
|
|
// buckets, too small and we waste a lot of space. I wrote
|
|
// a simple program to check some stats for different loads:
|
|
// (64-bit, 8 byte keys and values)
|
|
// loadFactor %overflow bytes/entry hitprobe missprobe
|
|
// 4.00 2.13 20.77 3.00 4.00
|
|
// 4.50 4.05 17.30 3.25 4.50
|
|
// 5.00 6.85 14.77 3.50 5.00
|
|
// 5.50 10.55 12.94 3.75 5.50
|
|
// 6.00 15.27 11.67 4.00 6.00
|
|
// 6.50 20.90 10.79 4.25 6.50
|
|
// 7.00 27.14 10.15 4.50 7.00
|
|
// 7.50 34.03 9.73 4.75 7.50
|
|
// 8.00 41.10 9.40 5.00 8.00
|
|
//
|
|
// %overflow = percentage of buckets which have an overflow bucket
|
|
// bytes/entry = overhead bytes used per key/value pair
|
|
// hitprobe = # of entries to check when looking up a present key
|
|
// missprobe = # of entries to check when looking up an absent key
|
|
//
|
|
// Keep in mind this data is for maximally loaded tables, i.e. just
|
|
// before the table grows. Typical tables will be somewhat less loaded.
|
|
|
|
import (
|
|
"unsafe"
|
|
)
|
|
|
|
const (
|
|
// Maximum number of key/value pairs a bucket can hold.
|
|
bucketCntBits = 3
|
|
bucketCnt = 1 << bucketCntBits
|
|
|
|
// Maximum average load of a bucket that triggers growth.
|
|
loadFactor = 6.5
|
|
|
|
// Maximum key or value size to keep inline (instead of mallocing per element).
|
|
// Must fit in a uint8.
|
|
// Fast versions cannot handle big values - the cutoff size for
|
|
// fast versions in ../../cmd/gc/walk.c must be at most this value.
|
|
maxKeySize = 128
|
|
maxValueSize = 128
|
|
|
|
// data offset should be the size of the bmap struct, but needs to be
|
|
// aligned correctly. For amd64p32 this means 64-bit alignment
|
|
// even though pointers are 32 bit.
|
|
dataOffset = unsafe.Offsetof(struct {
|
|
b bmap
|
|
v int64
|
|
}{}.v)
|
|
|
|
// Possible tophash values. We reserve a few possibilities for special marks.
|
|
// Each bucket (including its overflow buckets, if any) will have either all or none of its
|
|
// entries in the evacuated* states (except during the evacuate() method, which only happens
|
|
// during map writes and thus no one else can observe the map during that time).
|
|
empty = 0 // cell is empty
|
|
evacuatedEmpty = 1 // cell is empty, bucket is evacuated.
|
|
evacuatedX = 2 // key/value is valid. Entry has been evacuated to first half of larger table.
|
|
evacuatedY = 3 // same as above, but evacuated to second half of larger table.
|
|
minTopHash = 4 // minimum tophash for a normal filled cell.
|
|
|
|
// flags
|
|
iterator = 1 // there may be an iterator using buckets
|
|
oldIterator = 2 // there may be an iterator using oldbuckets
|
|
|
|
// sentinel bucket ID for iterator checks
|
|
noCheck = 1<<(8*ptrSize) - 1
|
|
|
|
// trigger a garbage collection at every alloc called from this code
|
|
checkgc = false
|
|
)
|
|
|
|
// A header for a Go map.
|
|
type hmap struct {
|
|
// Note: the format of the Hmap is encoded in ../../cmd/gc/reflect.c and
|
|
// ../reflect/type.go. Don't change this structure without also changing that code!
|
|
count int // # live cells == size of map. Must be first (used by len() builtin)
|
|
flags uint32
|
|
hash0 uint32 // hash seed
|
|
B uint8 // log_2 of # of buckets (can hold up to loadFactor * 2^B items)
|
|
|
|
buckets unsafe.Pointer // array of 2^B Buckets. may be nil if count==0.
|
|
oldbuckets unsafe.Pointer // previous bucket array of half the size, non-nil only when growing
|
|
nevacuate uintptr // progress counter for evacuation (buckets less than this have been evacuated)
|
|
}
|
|
|
|
// A bucket for a Go map.
|
|
type bmap struct {
|
|
tophash [bucketCnt]uint8
|
|
// Followed by bucketCnt keys and then bucketCnt values.
|
|
// NOTE: packing all the keys together and then all the values together makes the
|
|
// code a bit more complicated than alternating key/value/key/value/... but it allows
|
|
// us to eliminate padding which would be needed for, e.g., map[int64]int8.
|
|
// Followed by an overflow pointer.
|
|
}
|
|
|
|
// A hash iteration structure.
|
|
// If you modify hiter, also change cmd/gc/reflect.c to indicate
|
|
// the layout of this structure.
|
|
type hiter struct {
|
|
key unsafe.Pointer // Must be in first position. Write nil to indicate iteration end (see cmd/gc/range.c).
|
|
value unsafe.Pointer // Must be in second position (see cmd/gc/range.c).
|
|
t *maptype
|
|
h *hmap
|
|
buckets unsafe.Pointer // bucket ptr at hash_iter initialization time
|
|
bptr *bmap // current bucket
|
|
startBucket uintptr // bucket iteration started at
|
|
offset uint8 // intra-bucket offset to start from during iteration (should be big enough to hold bucketCnt-1)
|
|
wrapped bool // already wrapped around from end of bucket array to beginning
|
|
B uint8
|
|
i uint8
|
|
bucket uintptr
|
|
checkBucket uintptr
|
|
}
|
|
|
|
func evacuated(b *bmap) bool {
|
|
h := b.tophash[0]
|
|
return h > empty && h < minTopHash
|
|
}
|
|
|
|
func (b *bmap) overflow(t *maptype) *bmap {
|
|
return *(**bmap)(add(unsafe.Pointer(b), uintptr(t.bucketsize)-regSize))
|
|
}
|
|
func (b *bmap) setoverflow(t *maptype, ovf *bmap) {
|
|
*(**bmap)(add(unsafe.Pointer(b), uintptr(t.bucketsize)-regSize)) = ovf
|
|
}
|
|
|
|
func makemap(t *maptype, hint int64) *hmap {
|
|
if sz := unsafe.Sizeof(hmap{}); sz > 48 || sz != uintptr(t.hmap.size) {
|
|
gothrow("bad hmap size")
|
|
}
|
|
|
|
if hint < 0 || int64(int32(hint)) != hint {
|
|
panic("makemap: size out of range")
|
|
// TODO: make hint an int, then none of this nonsense
|
|
}
|
|
|
|
if !ismapkey(t.key) {
|
|
gothrow("runtime.makemap: unsupported map key type")
|
|
}
|
|
|
|
// check compiler's and reflect's math
|
|
if t.key.size > maxKeySize && (!t.indirectkey || t.keysize != uint8(ptrSize)) ||
|
|
t.key.size <= maxKeySize && (t.indirectkey || t.keysize != uint8(t.key.size)) {
|
|
gothrow("key size wrong")
|
|
}
|
|
if t.elem.size > maxValueSize && (!t.indirectvalue || t.valuesize != uint8(ptrSize)) ||
|
|
t.elem.size <= maxValueSize && (t.indirectvalue || t.valuesize != uint8(t.elem.size)) {
|
|
gothrow("value size wrong")
|
|
}
|
|
|
|
// invariants we depend on. We should probably check these at compile time
|
|
// somewhere, but for now we'll do it here.
|
|
if t.key.align > bucketCnt {
|
|
gothrow("key align too big")
|
|
}
|
|
if t.elem.align > bucketCnt {
|
|
gothrow("value align too big")
|
|
}
|
|
if uintptr(t.key.size)%uintptr(t.key.align) != 0 {
|
|
gothrow("key size not a multiple of key align")
|
|
}
|
|
if uintptr(t.elem.size)%uintptr(t.elem.align) != 0 {
|
|
gothrow("value size not a multiple of value align")
|
|
}
|
|
if bucketCnt < 8 {
|
|
gothrow("bucketsize too small for proper alignment")
|
|
}
|
|
if dataOffset%uintptr(t.key.align) != 0 {
|
|
gothrow("need padding in bucket (key)")
|
|
}
|
|
if dataOffset%uintptr(t.elem.align) != 0 {
|
|
gothrow("need padding in bucket (value)")
|
|
}
|
|
|
|
// find size parameter which will hold the requested # of elements
|
|
B := uint8(0)
|
|
for ; hint > bucketCnt && float32(hint) > loadFactor*float32(uintptr(1)<<B); B++ {
|
|
}
|
|
|
|
// allocate initial hash table
|
|
// if B == 0, the buckets field is allocated lazily later (in mapassign)
|
|
// If hint is large zeroing this memory could take a while.
|
|
var buckets unsafe.Pointer
|
|
if B != 0 {
|
|
if checkgc {
|
|
memstats.next_gc = memstats.heap_alloc
|
|
}
|
|
buckets = newarray(t.bucket, uintptr(1)<<B)
|
|
}
|
|
|
|
// initialize Hmap
|
|
if checkgc {
|
|
memstats.next_gc = memstats.heap_alloc
|
|
}
|
|
h := (*hmap)(newobject(t.hmap))
|
|
h.count = 0
|
|
h.B = B
|
|
h.flags = 0
|
|
h.hash0 = fastrand1()
|
|
h.buckets = buckets
|
|
h.oldbuckets = nil
|
|
h.nevacuate = 0
|
|
|
|
return h
|
|
}
|
|
|
|
// mapaccess1 returns a pointer to h[key]. Never returns nil, instead
|
|
// it will return a reference to the zero object for the value type if
|
|
// the key is not in the map.
|
|
// NOTE: The returned pointer may keep the whole map live, so don't
|
|
// hold onto it for very long.
|
|
func mapaccess1(t *maptype, h *hmap, key unsafe.Pointer) unsafe.Pointer {
|
|
if raceenabled && h != nil {
|
|
callerpc := getcallerpc(unsafe.Pointer(&t))
|
|
pc := funcPC(mapaccess1)
|
|
racereadpc(unsafe.Pointer(h), callerpc, pc)
|
|
raceReadObjectPC(t.key, key, callerpc, pc)
|
|
}
|
|
if h == nil || h.count == 0 {
|
|
return unsafe.Pointer(t.elem.zero)
|
|
}
|
|
alg := goalg(t.key.alg)
|
|
hash := alg.hash(key, uintptr(t.key.size), uintptr(h.hash0))
|
|
m := uintptr(1)<<h.B - 1
|
|
b := (*bmap)(add(h.buckets, (hash&m)*uintptr(t.bucketsize)))
|
|
if c := h.oldbuckets; c != nil {
|
|
oldb := (*bmap)(add(c, (hash&(m>>1))*uintptr(t.bucketsize)))
|
|
if !evacuated(oldb) {
|
|
b = oldb
|
|
}
|
|
}
|
|
top := uint8(hash >> (ptrSize*8 - 8))
|
|
if top < minTopHash {
|
|
top += minTopHash
|
|
}
|
|
for {
|
|
for i := uintptr(0); i < bucketCnt; i++ {
|
|
if b.tophash[i] != top {
|
|
continue
|
|
}
|
|
k := add(unsafe.Pointer(b), dataOffset+i*uintptr(t.keysize))
|
|
if t.indirectkey {
|
|
k = *((*unsafe.Pointer)(k))
|
|
}
|
|
if alg.equal(key, k, uintptr(t.key.size)) {
|
|
v := add(unsafe.Pointer(b), dataOffset+bucketCnt*uintptr(t.keysize)+i*uintptr(t.valuesize))
|
|
if t.indirectvalue {
|
|
v = *((*unsafe.Pointer)(v))
|
|
}
|
|
return v
|
|
}
|
|
}
|
|
b = b.overflow(t)
|
|
if b == nil {
|
|
return unsafe.Pointer(t.elem.zero)
|
|
}
|
|
}
|
|
}
|
|
|
|
func mapaccess2(t *maptype, h *hmap, key unsafe.Pointer) (unsafe.Pointer, bool) {
|
|
if raceenabled && h != nil {
|
|
callerpc := getcallerpc(unsafe.Pointer(&t))
|
|
pc := funcPC(mapaccess2)
|
|
racereadpc(unsafe.Pointer(h), callerpc, pc)
|
|
raceReadObjectPC(t.key, key, callerpc, pc)
|
|
}
|
|
if h == nil || h.count == 0 {
|
|
return unsafe.Pointer(t.elem.zero), false
|
|
}
|
|
alg := goalg(t.key.alg)
|
|
hash := alg.hash(key, uintptr(t.key.size), uintptr(h.hash0))
|
|
m := uintptr(1)<<h.B - 1
|
|
b := (*bmap)(unsafe.Pointer(uintptr(h.buckets) + (hash&m)*uintptr(t.bucketsize)))
|
|
if c := h.oldbuckets; c != nil {
|
|
oldb := (*bmap)(unsafe.Pointer(uintptr(c) + (hash&(m>>1))*uintptr(t.bucketsize)))
|
|
if !evacuated(oldb) {
|
|
b = oldb
|
|
}
|
|
}
|
|
top := uint8(hash >> (ptrSize*8 - 8))
|
|
if top < minTopHash {
|
|
top += minTopHash
|
|
}
|
|
for {
|
|
for i := uintptr(0); i < bucketCnt; i++ {
|
|
if b.tophash[i] != top {
|
|
continue
|
|
}
|
|
k := add(unsafe.Pointer(b), dataOffset+i*uintptr(t.keysize))
|
|
if t.indirectkey {
|
|
k = *((*unsafe.Pointer)(k))
|
|
}
|
|
if alg.equal(key, k, uintptr(t.key.size)) {
|
|
v := add(unsafe.Pointer(b), dataOffset+bucketCnt*uintptr(t.keysize)+i*uintptr(t.valuesize))
|
|
if t.indirectvalue {
|
|
v = *((*unsafe.Pointer)(v))
|
|
}
|
|
return v, true
|
|
}
|
|
}
|
|
b = b.overflow(t)
|
|
if b == nil {
|
|
return unsafe.Pointer(t.elem.zero), false
|
|
}
|
|
}
|
|
}
|
|
|
|
// returns both key and value. Used by map iterator
|
|
func mapaccessK(t *maptype, h *hmap, key unsafe.Pointer) (unsafe.Pointer, unsafe.Pointer) {
|
|
if h == nil || h.count == 0 {
|
|
return nil, nil
|
|
}
|
|
alg := goalg(t.key.alg)
|
|
hash := alg.hash(key, uintptr(t.key.size), uintptr(h.hash0))
|
|
m := uintptr(1)<<h.B - 1
|
|
b := (*bmap)(unsafe.Pointer(uintptr(h.buckets) + (hash&m)*uintptr(t.bucketsize)))
|
|
if c := h.oldbuckets; c != nil {
|
|
oldb := (*bmap)(unsafe.Pointer(uintptr(c) + (hash&(m>>1))*uintptr(t.bucketsize)))
|
|
if !evacuated(oldb) {
|
|
b = oldb
|
|
}
|
|
}
|
|
top := uint8(hash >> (ptrSize*8 - 8))
|
|
if top < minTopHash {
|
|
top += minTopHash
|
|
}
|
|
for {
|
|
for i := uintptr(0); i < bucketCnt; i++ {
|
|
if b.tophash[i] != top {
|
|
continue
|
|
}
|
|
k := add(unsafe.Pointer(b), dataOffset+i*uintptr(t.keysize))
|
|
if t.indirectkey {
|
|
k = *((*unsafe.Pointer)(k))
|
|
}
|
|
if alg.equal(key, k, uintptr(t.key.size)) {
|
|
v := add(unsafe.Pointer(b), dataOffset+bucketCnt*uintptr(t.keysize)+i*uintptr(t.valuesize))
|
|
if t.indirectvalue {
|
|
v = *((*unsafe.Pointer)(v))
|
|
}
|
|
return k, v
|
|
}
|
|
}
|
|
b = b.overflow(t)
|
|
if b == nil {
|
|
return nil, nil
|
|
}
|
|
}
|
|
}
|
|
|
|
func mapassign1(t *maptype, h *hmap, key unsafe.Pointer, val unsafe.Pointer) {
|
|
if h == nil {
|
|
panic("assignment to entry in nil map")
|
|
}
|
|
if raceenabled {
|
|
callerpc := getcallerpc(unsafe.Pointer(&t))
|
|
pc := funcPC(mapassign1)
|
|
racewritepc(unsafe.Pointer(h), callerpc, pc)
|
|
raceReadObjectPC(t.key, key, callerpc, pc)
|
|
raceReadObjectPC(t.elem, val, callerpc, pc)
|
|
}
|
|
|
|
alg := goalg(t.key.alg)
|
|
hash := alg.hash(key, uintptr(t.key.size), uintptr(h.hash0))
|
|
|
|
if h.buckets == nil {
|
|
if checkgc {
|
|
memstats.next_gc = memstats.heap_alloc
|
|
}
|
|
h.buckets = newarray(t.bucket, 1)
|
|
}
|
|
|
|
again:
|
|
bucket := hash & (uintptr(1)<<h.B - 1)
|
|
if h.oldbuckets != nil {
|
|
growWork(t, h, bucket)
|
|
}
|
|
b := (*bmap)(unsafe.Pointer(uintptr(h.buckets) + bucket*uintptr(t.bucketsize)))
|
|
top := uint8(hash >> (ptrSize*8 - 8))
|
|
if top < minTopHash {
|
|
top += minTopHash
|
|
}
|
|
|
|
var inserti *uint8
|
|
var insertk unsafe.Pointer
|
|
var insertv unsafe.Pointer
|
|
for {
|
|
for i := uintptr(0); i < bucketCnt; i++ {
|
|
if b.tophash[i] != top {
|
|
if b.tophash[i] == empty && inserti == nil {
|
|
inserti = &b.tophash[i]
|
|
insertk = add(unsafe.Pointer(b), dataOffset+i*uintptr(t.keysize))
|
|
insertv = add(unsafe.Pointer(b), dataOffset+bucketCnt*uintptr(t.keysize)+i*uintptr(t.valuesize))
|
|
}
|
|
continue
|
|
}
|
|
k := add(unsafe.Pointer(b), dataOffset+i*uintptr(t.keysize))
|
|
k2 := k
|
|
if t.indirectkey {
|
|
k2 = *((*unsafe.Pointer)(k2))
|
|
}
|
|
if !alg.equal(key, k2, uintptr(t.key.size)) {
|
|
continue
|
|
}
|
|
// already have a mapping for key. Update it.
|
|
memmove(k2, key, uintptr(t.key.size))
|
|
v := add(unsafe.Pointer(b), dataOffset+bucketCnt*uintptr(t.keysize)+i*uintptr(t.valuesize))
|
|
v2 := v
|
|
if t.indirectvalue {
|
|
v2 = *((*unsafe.Pointer)(v2))
|
|
}
|
|
memmove(v2, val, uintptr(t.elem.size))
|
|
return
|
|
}
|
|
ovf := b.overflow(t)
|
|
if ovf == nil {
|
|
break
|
|
}
|
|
b = ovf
|
|
}
|
|
|
|
// did not find mapping for key. Allocate new cell & add entry.
|
|
if float32(h.count) >= loadFactor*float32((uintptr(1)<<h.B)) && h.count >= bucketCnt {
|
|
hashGrow(t, h)
|
|
goto again // Growing the table invalidates everything, so try again
|
|
}
|
|
|
|
if inserti == nil {
|
|
// all current buckets are full, allocate a new one.
|
|
if checkgc {
|
|
memstats.next_gc = memstats.heap_alloc
|
|
}
|
|
newb := (*bmap)(newobject(t.bucket))
|
|
b.setoverflow(t, newb)
|
|
inserti = &newb.tophash[0]
|
|
insertk = add(unsafe.Pointer(newb), dataOffset)
|
|
insertv = add(insertk, bucketCnt*uintptr(t.keysize))
|
|
}
|
|
|
|
// store new key/value at insert position
|
|
if t.indirectkey {
|
|
if checkgc {
|
|
memstats.next_gc = memstats.heap_alloc
|
|
}
|
|
kmem := newobject(t.key)
|
|
*(*unsafe.Pointer)(insertk) = kmem
|
|
insertk = kmem
|
|
}
|
|
if t.indirectvalue {
|
|
if checkgc {
|
|
memstats.next_gc = memstats.heap_alloc
|
|
}
|
|
vmem := newobject(t.elem)
|
|
*(*unsafe.Pointer)(insertv) = vmem
|
|
insertv = vmem
|
|
}
|
|
memmove(insertk, key, uintptr(t.key.size))
|
|
memmove(insertv, val, uintptr(t.elem.size))
|
|
*inserti = top
|
|
h.count++
|
|
}
|
|
|
|
func mapdelete(t *maptype, h *hmap, key unsafe.Pointer) {
|
|
if raceenabled && h != nil {
|
|
callerpc := getcallerpc(unsafe.Pointer(&t))
|
|
pc := funcPC(mapdelete)
|
|
racewritepc(unsafe.Pointer(h), callerpc, pc)
|
|
raceReadObjectPC(t.key, key, callerpc, pc)
|
|
}
|
|
if h == nil || h.count == 0 {
|
|
return
|
|
}
|
|
alg := goalg(t.key.alg)
|
|
hash := alg.hash(key, uintptr(t.key.size), uintptr(h.hash0))
|
|
bucket := hash & (uintptr(1)<<h.B - 1)
|
|
if h.oldbuckets != nil {
|
|
growWork(t, h, bucket)
|
|
}
|
|
b := (*bmap)(unsafe.Pointer(uintptr(h.buckets) + bucket*uintptr(t.bucketsize)))
|
|
top := uint8(hash >> (ptrSize*8 - 8))
|
|
if top < minTopHash {
|
|
top += minTopHash
|
|
}
|
|
for {
|
|
for i := uintptr(0); i < bucketCnt; i++ {
|
|
if b.tophash[i] != top {
|
|
continue
|
|
}
|
|
k := add(unsafe.Pointer(b), dataOffset+i*uintptr(t.keysize))
|
|
k2 := k
|
|
if t.indirectkey {
|
|
k2 = *((*unsafe.Pointer)(k2))
|
|
}
|
|
if !alg.equal(key, k2, uintptr(t.key.size)) {
|
|
continue
|
|
}
|
|
memclr(k, uintptr(t.keysize))
|
|
v := unsafe.Pointer(uintptr(unsafe.Pointer(b)) + dataOffset + bucketCnt*uintptr(t.keysize) + i*uintptr(t.valuesize))
|
|
memclr(v, uintptr(t.valuesize))
|
|
b.tophash[i] = empty
|
|
h.count--
|
|
return
|
|
}
|
|
b = b.overflow(t)
|
|
if b == nil {
|
|
return
|
|
}
|
|
}
|
|
}
|
|
|
|
func mapiterinit(t *maptype, h *hmap, it *hiter) {
|
|
// Clear pointer fields so garbage collector does not complain.
|
|
it.key = nil
|
|
it.value = nil
|
|
it.t = nil
|
|
it.h = nil
|
|
it.buckets = nil
|
|
it.bptr = nil
|
|
|
|
if raceenabled && h != nil {
|
|
callerpc := getcallerpc(unsafe.Pointer(&t))
|
|
racereadpc(unsafe.Pointer(h), callerpc, funcPC(mapiterinit))
|
|
}
|
|
|
|
if h == nil || h.count == 0 {
|
|
it.key = nil
|
|
it.value = nil
|
|
return
|
|
}
|
|
|
|
if unsafe.Sizeof(hiter{})/ptrSize != 10 {
|
|
gothrow("hash_iter size incorrect") // see ../../cmd/gc/reflect.c
|
|
}
|
|
it.t = t
|
|
it.h = h
|
|
|
|
// grab snapshot of bucket state
|
|
it.B = h.B
|
|
it.buckets = h.buckets
|
|
|
|
// decide where to start
|
|
r := uintptr(fastrand1())
|
|
if h.B > 31-bucketCntBits {
|
|
r += uintptr(fastrand1()) << 31
|
|
}
|
|
it.startBucket = r & (uintptr(1)<<h.B - 1)
|
|
it.offset = uint8(r >> h.B & (bucketCnt - 1))
|
|
|
|
// iterator state
|
|
it.bucket = it.startBucket
|
|
it.wrapped = false
|
|
it.bptr = nil
|
|
|
|
// Remember we have an iterator.
|
|
// Can run concurrently with another hash_iter_init().
|
|
for {
|
|
old := h.flags
|
|
if old == old|iterator|oldIterator {
|
|
break
|
|
}
|
|
if cas(&h.flags, old, old|iterator|oldIterator) {
|
|
break
|
|
}
|
|
}
|
|
|
|
mapiternext(it)
|
|
}
|
|
|
|
func mapiternext(it *hiter) {
|
|
h := it.h
|
|
if raceenabled {
|
|
callerpc := getcallerpc(unsafe.Pointer(&it))
|
|
racereadpc(unsafe.Pointer(h), callerpc, funcPC(mapiternext))
|
|
}
|
|
t := it.t
|
|
bucket := it.bucket
|
|
b := it.bptr
|
|
i := it.i
|
|
checkBucket := it.checkBucket
|
|
alg := goalg(t.key.alg)
|
|
|
|
next:
|
|
if b == nil {
|
|
if bucket == it.startBucket && it.wrapped {
|
|
// end of iteration
|
|
it.key = nil
|
|
it.value = nil
|
|
return
|
|
}
|
|
if h.oldbuckets != nil && it.B == h.B {
|
|
// Iterator was started in the middle of a grow, and the grow isn't done yet.
|
|
// If the bucket we're looking at hasn't been filled in yet (i.e. the old
|
|
// bucket hasn't been evacuated) then we need to iterate through the old
|
|
// bucket and only return the ones that will be migrated to this bucket.
|
|
oldbucket := bucket & (uintptr(1)<<(it.B-1) - 1)
|
|
b = (*bmap)(add(h.oldbuckets, oldbucket*uintptr(t.bucketsize)))
|
|
if !evacuated(b) {
|
|
checkBucket = bucket
|
|
} else {
|
|
b = (*bmap)(add(it.buckets, bucket*uintptr(t.bucketsize)))
|
|
checkBucket = noCheck
|
|
}
|
|
} else {
|
|
b = (*bmap)(add(it.buckets, bucket*uintptr(t.bucketsize)))
|
|
checkBucket = noCheck
|
|
}
|
|
bucket++
|
|
if bucket == uintptr(1)<<it.B {
|
|
bucket = 0
|
|
it.wrapped = true
|
|
}
|
|
i = 0
|
|
}
|
|
for ; i < bucketCnt; i++ {
|
|
offi := (i + it.offset) & (bucketCnt - 1)
|
|
k := add(unsafe.Pointer(b), dataOffset+uintptr(offi)*uintptr(t.keysize))
|
|
v := add(unsafe.Pointer(b), dataOffset+bucketCnt*uintptr(t.keysize)+uintptr(offi)*uintptr(t.valuesize))
|
|
if b.tophash[offi] != empty && b.tophash[offi] != evacuatedEmpty {
|
|
if checkBucket != noCheck {
|
|
// Special case: iterator was started during a grow and the
|
|
// grow is not done yet. We're working on a bucket whose
|
|
// oldbucket has not been evacuated yet. Or at least, it wasn't
|
|
// evacuated when we started the bucket. So we're iterating
|
|
// through the oldbucket, skipping any keys that will go
|
|
// to the other new bucket (each oldbucket expands to two
|
|
// buckets during a grow).
|
|
k2 := k
|
|
if t.indirectkey {
|
|
k2 = *((*unsafe.Pointer)(k2))
|
|
}
|
|
if alg.equal(k2, k2, uintptr(t.key.size)) {
|
|
// If the item in the oldbucket is not destined for
|
|
// the current new bucket in the iteration, skip it.
|
|
hash := alg.hash(k2, uintptr(t.key.size), uintptr(h.hash0))
|
|
if hash&(uintptr(1)<<it.B-1) != checkBucket {
|
|
continue
|
|
}
|
|
} else {
|
|
// Hash isn't repeatable if k != k (NaNs). We need a
|
|
// repeatable and randomish choice of which direction
|
|
// to send NaNs during evacuation. We'll use the low
|
|
// bit of tophash to decide which way NaNs go.
|
|
// NOTE: this case is why we need two evacuate tophash
|
|
// values, evacuatedX and evacuatedY, that differ in
|
|
// their low bit.
|
|
if checkBucket>>(it.B-1) != uintptr(b.tophash[offi]&1) {
|
|
continue
|
|
}
|
|
}
|
|
}
|
|
if b.tophash[offi] != evacuatedX && b.tophash[offi] != evacuatedY {
|
|
// this is the golden data, we can return it.
|
|
if t.indirectkey {
|
|
k = *((*unsafe.Pointer)(k))
|
|
}
|
|
it.key = k
|
|
if t.indirectvalue {
|
|
v = *((*unsafe.Pointer)(v))
|
|
}
|
|
it.value = v
|
|
} else {
|
|
// The hash table has grown since the iterator was started.
|
|
// The golden data for this key is now somewhere else.
|
|
k2 := k
|
|
if t.indirectkey {
|
|
k2 = *((*unsafe.Pointer)(k2))
|
|
}
|
|
if alg.equal(k2, k2, uintptr(t.key.size)) {
|
|
// Check the current hash table for the data.
|
|
// This code handles the case where the key
|
|
// has been deleted, updated, or deleted and reinserted.
|
|
// NOTE: we need to regrab the key as it has potentially been
|
|
// updated to an equal() but not identical key (e.g. +0.0 vs -0.0).
|
|
rk, rv := mapaccessK(t, h, k2)
|
|
if rk == nil {
|
|
continue // key has been deleted
|
|
}
|
|
it.key = rk
|
|
it.value = rv
|
|
} else {
|
|
// if key!=key then the entry can't be deleted or
|
|
// updated, so we can just return it. That's lucky for
|
|
// us because when key!=key we can't look it up
|
|
// successfully in the current table.
|
|
it.key = k2
|
|
if t.indirectvalue {
|
|
v = *((*unsafe.Pointer)(v))
|
|
}
|
|
it.value = v
|
|
}
|
|
}
|
|
it.bucket = bucket
|
|
it.bptr = b
|
|
it.i = i + 1
|
|
it.checkBucket = checkBucket
|
|
return
|
|
}
|
|
}
|
|
b = b.overflow(t)
|
|
i = 0
|
|
goto next
|
|
}
|
|
|
|
func hashGrow(t *maptype, h *hmap) {
|
|
if h.oldbuckets != nil {
|
|
gothrow("evacuation not done in time")
|
|
}
|
|
oldbuckets := h.buckets
|
|
if checkgc {
|
|
memstats.next_gc = memstats.heap_alloc
|
|
}
|
|
newbuckets := newarray(t.bucket, uintptr(1)<<(h.B+1))
|
|
flags := h.flags &^ (iterator | oldIterator)
|
|
if h.flags&iterator != 0 {
|
|
flags |= oldIterator
|
|
}
|
|
// commit the grow (atomic wrt gc)
|
|
h.B++
|
|
h.flags = flags
|
|
h.oldbuckets = oldbuckets
|
|
h.buckets = newbuckets
|
|
h.nevacuate = 0
|
|
|
|
// the actual copying of the hash table data is done incrementally
|
|
// by growWork() and evacuate().
|
|
}
|
|
|
|
func growWork(t *maptype, h *hmap, bucket uintptr) {
|
|
noldbuckets := uintptr(1) << (h.B - 1)
|
|
|
|
// make sure we evacuate the oldbucket corresponding
|
|
// to the bucket we're about to use
|
|
evacuate(t, h, bucket&(noldbuckets-1))
|
|
|
|
// evacuate one more oldbucket to make progress on growing
|
|
if h.oldbuckets != nil {
|
|
evacuate(t, h, h.nevacuate)
|
|
}
|
|
}
|
|
|
|
func evacuate(t *maptype, h *hmap, oldbucket uintptr) {
|
|
b := (*bmap)(add(h.oldbuckets, oldbucket*uintptr(t.bucketsize)))
|
|
newbit := uintptr(1) << (h.B - 1)
|
|
alg := goalg(t.key.alg)
|
|
if !evacuated(b) {
|
|
// TODO: reuse overflow buckets instead of using new ones, if there
|
|
// is no iterator using the old buckets. (If !oldIterator.)
|
|
|
|
x := (*bmap)(add(h.buckets, oldbucket*uintptr(t.bucketsize)))
|
|
y := (*bmap)(add(h.buckets, (oldbucket+newbit)*uintptr(t.bucketsize)))
|
|
xi := 0
|
|
yi := 0
|
|
xk := add(unsafe.Pointer(x), dataOffset)
|
|
yk := add(unsafe.Pointer(y), dataOffset)
|
|
xv := add(xk, bucketCnt*uintptr(t.keysize))
|
|
yv := add(yk, bucketCnt*uintptr(t.keysize))
|
|
for ; b != nil; b = b.overflow(t) {
|
|
k := add(unsafe.Pointer(b), dataOffset)
|
|
v := add(k, bucketCnt*uintptr(t.keysize))
|
|
for i := 0; i < bucketCnt; i, k, v = i+1, add(k, uintptr(t.keysize)), add(v, uintptr(t.valuesize)) {
|
|
top := b.tophash[i]
|
|
if top == empty {
|
|
b.tophash[i] = evacuatedEmpty
|
|
continue
|
|
}
|
|
if top < minTopHash {
|
|
gothrow("bad map state")
|
|
}
|
|
k2 := k
|
|
if t.indirectkey {
|
|
k2 = *((*unsafe.Pointer)(k2))
|
|
}
|
|
// Compute hash to make our evacuation decision (whether we need
|
|
// to send this key/value to bucket x or bucket y).
|
|
hash := alg.hash(k2, uintptr(t.key.size), uintptr(h.hash0))
|
|
if h.flags&iterator != 0 {
|
|
if !alg.equal(k2, k2, uintptr(t.key.size)) {
|
|
// If key != key (NaNs), then the hash could be (and probably
|
|
// will be) entirely different from the old hash. Moreover,
|
|
// it isn't reproducible. Reproducibility is required in the
|
|
// presence of iterators, as our evacuation decision must
|
|
// match whatever decision the iterator made.
|
|
// Fortunately, we have the freedom to send these keys either
|
|
// way. Also, tophash is meaningless for these kinds of keys.
|
|
// We let the low bit of tophash drive the evacuation decision.
|
|
// We recompute a new random tophash for the next level so
|
|
// these keys will get evenly distributed across all buckets
|
|
// after multiple grows.
|
|
if (top & 1) != 0 {
|
|
hash |= newbit
|
|
} else {
|
|
hash &^= newbit
|
|
}
|
|
top = uint8(hash >> (ptrSize*8 - 8))
|
|
if top < minTopHash {
|
|
top += minTopHash
|
|
}
|
|
}
|
|
}
|
|
if (hash & newbit) == 0 {
|
|
b.tophash[i] = evacuatedX
|
|
if xi == bucketCnt {
|
|
if checkgc {
|
|
memstats.next_gc = memstats.heap_alloc
|
|
}
|
|
newx := (*bmap)(newobject(t.bucket))
|
|
x.setoverflow(t, newx)
|
|
x = newx
|
|
xi = 0
|
|
xk = add(unsafe.Pointer(x), dataOffset)
|
|
xv = add(xk, bucketCnt*uintptr(t.keysize))
|
|
}
|
|
x.tophash[xi] = top
|
|
if t.indirectkey {
|
|
*(*unsafe.Pointer)(xk) = k2 // copy pointer
|
|
} else {
|
|
memmove(xk, k, uintptr(t.key.size)) // copy value
|
|
}
|
|
if t.indirectvalue {
|
|
*(*unsafe.Pointer)(xv) = *(*unsafe.Pointer)(v)
|
|
} else {
|
|
memmove(xv, v, uintptr(t.elem.size))
|
|
}
|
|
xi++
|
|
xk = add(xk, uintptr(t.keysize))
|
|
xv = add(xv, uintptr(t.valuesize))
|
|
} else {
|
|
b.tophash[i] = evacuatedY
|
|
if yi == bucketCnt {
|
|
if checkgc {
|
|
memstats.next_gc = memstats.heap_alloc
|
|
}
|
|
newy := (*bmap)(newobject(t.bucket))
|
|
y.setoverflow(t, newy)
|
|
y = newy
|
|
yi = 0
|
|
yk = add(unsafe.Pointer(y), dataOffset)
|
|
yv = add(yk, bucketCnt*uintptr(t.keysize))
|
|
}
|
|
y.tophash[yi] = top
|
|
if t.indirectkey {
|
|
*(*unsafe.Pointer)(yk) = k2
|
|
} else {
|
|
memmove(yk, k, uintptr(t.key.size))
|
|
}
|
|
if t.indirectvalue {
|
|
*(*unsafe.Pointer)(yv) = *(*unsafe.Pointer)(v)
|
|
} else {
|
|
memmove(yv, v, uintptr(t.elem.size))
|
|
}
|
|
yi++
|
|
yk = add(yk, uintptr(t.keysize))
|
|
yv = add(yv, uintptr(t.valuesize))
|
|
}
|
|
}
|
|
}
|
|
// Unlink the overflow buckets & clear key/value to help GC.
|
|
if h.flags&oldIterator == 0 {
|
|
b = (*bmap)(add(h.oldbuckets, oldbucket*uintptr(t.bucketsize)))
|
|
memclr(add(unsafe.Pointer(b), dataOffset), uintptr(t.bucketsize)-dataOffset)
|
|
}
|
|
}
|
|
|
|
// Advance evacuation mark
|
|
if oldbucket == h.nevacuate {
|
|
h.nevacuate = oldbucket + 1
|
|
if oldbucket+1 == newbit { // newbit == # of oldbuckets
|
|
// Growing is all done. Free old main bucket array.
|
|
h.oldbuckets = nil
|
|
}
|
|
}
|
|
}
|
|
|
|
func ismapkey(t *_type) bool {
|
|
return goalg(t.alg).hash != nil
|
|
}
|
|
|
|
// Reflect stubs. Called from ../reflect/asm_*.s
|
|
|
|
func reflect_makemap(t *maptype) *hmap {
|
|
return makemap(t, 0)
|
|
}
|
|
|
|
func reflect_mapaccess(t *maptype, h *hmap, key unsafe.Pointer) unsafe.Pointer {
|
|
val, ok := mapaccess2(t, h, key)
|
|
if !ok {
|
|
// reflect wants nil for a missing element
|
|
val = nil
|
|
}
|
|
return val
|
|
}
|
|
|
|
func reflect_mapassign(t *maptype, h *hmap, key unsafe.Pointer, val unsafe.Pointer) {
|
|
mapassign1(t, h, key, val)
|
|
}
|
|
|
|
func reflect_mapdelete(t *maptype, h *hmap, key unsafe.Pointer) {
|
|
mapdelete(t, h, key)
|
|
}
|
|
|
|
func reflect_mapiterinit(t *maptype, h *hmap) *hiter {
|
|
it := new(hiter)
|
|
mapiterinit(t, h, it)
|
|
return it
|
|
}
|
|
|
|
func reflect_mapiternext(it *hiter) {
|
|
mapiternext(it)
|
|
}
|
|
|
|
func reflect_mapiterkey(it *hiter) unsafe.Pointer {
|
|
return it.key
|
|
}
|
|
|
|
func reflect_maplen(h *hmap) int {
|
|
if h == nil {
|
|
return 0
|
|
}
|
|
if raceenabled {
|
|
callerpc := getcallerpc(unsafe.Pointer(&h))
|
|
racereadpc(unsafe.Pointer(h), callerpc, funcPC(reflect_maplen))
|
|
}
|
|
return h.count
|
|
}
|
|
|
|
func reflect_ismapkey(t *_type) bool {
|
|
return ismapkey(t)
|
|
}
|