961 lines
28 KiB
Go
961 lines
28 KiB
Go
// Copyright 2014 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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// This file contains the implementation of Go's map type.
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//
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// A map is just a hash table. The data is arranged
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// into an array of buckets. Each bucket contains up to
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// 8 key/value pairs. The low-order bits of the hash are
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// used to select a bucket. Each bucket contains a few
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// high-order bits of each hash to distinguish the entries
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// within a single bucket.
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//
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// If more than 8 keys hash to a bucket, we chain on
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// extra buckets.
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//
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// When the hashtable grows, we allocate a new array
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// of buckets twice as big. Buckets are incrementally
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// copied from the old bucket array to the new bucket array.
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//
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// Map iterators walk through the array of buckets and
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// return the keys in walk order (bucket #, then overflow
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// chain order, then bucket index). To maintain iteration
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// semantics, we never move keys within their bucket (if
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// we did, keys might be returned 0 or 2 times). When
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// growing the table, iterators remain iterating through the
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// old table and must check the new table if the bucket
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// they are iterating through has been moved ("evacuated")
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// to the new table.
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// Picking loadFactor: too large and we have lots of overflow
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// buckets, too small and we waste a lot of space. I wrote
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// a simple program to check some stats for different loads:
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// (64-bit, 8 byte keys and values)
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// loadFactor %overflow bytes/entry hitprobe missprobe
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// 4.00 2.13 20.77 3.00 4.00
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// 4.50 4.05 17.30 3.25 4.50
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// 5.00 6.85 14.77 3.50 5.00
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// 5.50 10.55 12.94 3.75 5.50
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// 6.00 15.27 11.67 4.00 6.00
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// 6.50 20.90 10.79 4.25 6.50
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// 7.00 27.14 10.15 4.50 7.00
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// 7.50 34.03 9.73 4.75 7.50
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// 8.00 41.10 9.40 5.00 8.00
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//
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// %overflow = percentage of buckets which have an overflow bucket
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// bytes/entry = overhead bytes used per key/value pair
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// hitprobe = # of entries to check when looking up a present key
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// missprobe = # of entries to check when looking up an absent key
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//
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// Keep in mind this data is for maximally loaded tables, i.e. just
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// before the table grows. Typical tables will be somewhat less loaded.
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import (
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"unsafe"
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)
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const (
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// Maximum number of key/value pairs a bucket can hold.
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bucketCntBits = 3
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bucketCnt = 1 << bucketCntBits
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// Maximum average load of a bucket that triggers growth.
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loadFactor = 6.5
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// Maximum key or value size to keep inline (instead of mallocing per element).
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// Must fit in a uint8.
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// Fast versions cannot handle big values - the cutoff size for
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// fast versions in ../../cmd/gc/walk.c must be at most this value.
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maxKeySize = 128
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maxValueSize = 128
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// data offset should be the size of the bmap struct, but needs to be
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// aligned correctly. For amd64p32 this means 64-bit alignment
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// even though pointers are 32 bit.
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dataOffset = unsafe.Offsetof(struct {
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b bmap
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v int64
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}{}.v)
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// Possible tophash values. We reserve a few possibilities for special marks.
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// Each bucket (including its overflow buckets, if any) will have either all or none of its
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// entries in the evacuated* states (except during the evacuate() method, which only happens
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// during map writes and thus no one else can observe the map during that time).
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empty = 0 // cell is empty
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evacuatedEmpty = 1 // cell is empty, bucket is evacuated.
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evacuatedX = 2 // key/value is valid. Entry has been evacuated to first half of larger table.
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evacuatedY = 3 // same as above, but evacuated to second half of larger table.
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minTopHash = 4 // minimum tophash for a normal filled cell.
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// flags
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iterator = 1 // there may be an iterator using buckets
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oldIterator = 2 // there may be an iterator using oldbuckets
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// sentinel bucket ID for iterator checks
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noCheck = 1<<(8*ptrSize) - 1
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// trigger a garbage collection at every alloc called from this code
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checkgc = false
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)
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// A header for a Go map.
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type hmap struct {
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// Note: the format of the Hmap is encoded in ../../cmd/gc/reflect.c and
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// ../reflect/type.go. Don't change this structure without also changing that code!
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count int // # live cells == size of map. Must be first (used by len() builtin)
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flags uint32
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hash0 uint32 // hash seed
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B uint8 // log_2 of # of buckets (can hold up to loadFactor * 2^B items)
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buckets unsafe.Pointer // array of 2^B Buckets. may be nil if count==0.
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oldbuckets unsafe.Pointer // previous bucket array of half the size, non-nil only when growing
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nevacuate uintptr // progress counter for evacuation (buckets less than this have been evacuated)
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}
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// A bucket for a Go map.
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type bmap struct {
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tophash [bucketCnt]uint8
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// Followed by bucketCnt keys and then bucketCnt values.
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// NOTE: packing all the keys together and then all the values together makes the
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// code a bit more complicated than alternating key/value/key/value/... but it allows
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// us to eliminate padding which would be needed for, e.g., map[int64]int8.
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// Followed by an overflow pointer.
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}
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// A hash iteration structure.
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// If you modify hiter, also change cmd/gc/reflect.c to indicate
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// the layout of this structure.
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type hiter struct {
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key unsafe.Pointer // Must be in first position. Write nil to indicate iteration end (see cmd/gc/range.c).
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value unsafe.Pointer // Must be in second position (see cmd/gc/range.c).
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t *maptype
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h *hmap
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buckets unsafe.Pointer // bucket ptr at hash_iter initialization time
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bptr *bmap // current bucket
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startBucket uintptr // bucket iteration started at
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offset uint8 // intra-bucket offset to start from during iteration (should be big enough to hold bucketCnt-1)
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wrapped bool // already wrapped around from end of bucket array to beginning
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B uint8
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i uint8
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bucket uintptr
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checkBucket uintptr
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}
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func evacuated(b *bmap) bool {
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h := b.tophash[0]
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return h > empty && h < minTopHash
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}
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func (b *bmap) overflow(t *maptype) *bmap {
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return *(**bmap)(add(unsafe.Pointer(b), uintptr(t.bucketsize)-regSize))
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}
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func (b *bmap) setoverflow(t *maptype, ovf *bmap) {
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*(**bmap)(add(unsafe.Pointer(b), uintptr(t.bucketsize)-regSize)) = ovf
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}
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func makemap(t *maptype, hint int64) *hmap {
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if sz := unsafe.Sizeof(hmap{}); sz > 48 || sz != uintptr(t.hmap.size) {
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gothrow("bad hmap size")
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}
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if hint < 0 || int64(int32(hint)) != hint {
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panic("makemap: size out of range")
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// TODO: make hint an int, then none of this nonsense
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}
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if !ismapkey(t.key) {
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gothrow("runtime.makemap: unsupported map key type")
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}
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// check compiler's and reflect's math
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if t.key.size > maxKeySize && (!t.indirectkey || t.keysize != uint8(ptrSize)) ||
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t.key.size <= maxKeySize && (t.indirectkey || t.keysize != uint8(t.key.size)) {
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gothrow("key size wrong")
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}
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if t.elem.size > maxValueSize && (!t.indirectvalue || t.valuesize != uint8(ptrSize)) ||
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t.elem.size <= maxValueSize && (t.indirectvalue || t.valuesize != uint8(t.elem.size)) {
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gothrow("value size wrong")
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}
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// invariants we depend on. We should probably check these at compile time
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// somewhere, but for now we'll do it here.
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if t.key.align > bucketCnt {
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gothrow("key align too big")
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}
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if t.elem.align > bucketCnt {
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gothrow("value align too big")
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}
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if uintptr(t.key.size)%uintptr(t.key.align) != 0 {
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gothrow("key size not a multiple of key align")
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}
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if uintptr(t.elem.size)%uintptr(t.elem.align) != 0 {
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gothrow("value size not a multiple of value align")
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}
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if bucketCnt < 8 {
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gothrow("bucketsize too small for proper alignment")
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}
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if dataOffset%uintptr(t.key.align) != 0 {
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gothrow("need padding in bucket (key)")
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}
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if dataOffset%uintptr(t.elem.align) != 0 {
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gothrow("need padding in bucket (value)")
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}
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// find size parameter which will hold the requested # of elements
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B := uint8(0)
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for ; hint > bucketCnt && float32(hint) > loadFactor*float32(uintptr(1)<<B); B++ {
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}
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// allocate initial hash table
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// if B == 0, the buckets field is allocated lazily later (in mapassign)
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// If hint is large zeroing this memory could take a while.
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var buckets unsafe.Pointer
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if B != 0 {
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if checkgc {
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memstats.next_gc = memstats.heap_alloc
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}
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buckets = newarray(t.bucket, uintptr(1)<<B)
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}
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// initialize Hmap
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if checkgc {
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memstats.next_gc = memstats.heap_alloc
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}
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h := (*hmap)(newobject(t.hmap))
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h.count = 0
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h.B = B
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h.flags = 0
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h.hash0 = fastrand1()
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h.buckets = buckets
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h.oldbuckets = nil
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h.nevacuate = 0
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return h
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}
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// mapaccess1 returns a pointer to h[key]. Never returns nil, instead
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// it will return a reference to the zero object for the value type if
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// the key is not in the map.
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// NOTE: The returned pointer may keep the whole map live, so don't
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// hold onto it for very long.
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func mapaccess1(t *maptype, h *hmap, key unsafe.Pointer) unsafe.Pointer {
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if raceenabled && h != nil {
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callerpc := getcallerpc(unsafe.Pointer(&t))
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pc := funcPC(mapaccess1)
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racereadpc(unsafe.Pointer(h), callerpc, pc)
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raceReadObjectPC(t.key, key, callerpc, pc)
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}
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if h == nil || h.count == 0 {
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return unsafe.Pointer(t.elem.zero)
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}
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alg := goalg(t.key.alg)
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hash := alg.hash(key, uintptr(t.key.size), uintptr(h.hash0))
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m := uintptr(1)<<h.B - 1
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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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oldb := (*bmap)(add(c, (hash&(m>>1))*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 := uint8(hash >> (ptrSize*8 - 8))
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if top < minTopHash {
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top += minTopHash
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}
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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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continue
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}
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k := add(unsafe.Pointer(b), dataOffset+i*uintptr(t.keysize))
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if t.indirectkey {
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k = *((*unsafe.Pointer)(k))
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}
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if alg.equal(key, k, uintptr(t.key.size)) {
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v := add(unsafe.Pointer(b), dataOffset+bucketCnt*uintptr(t.keysize)+i*uintptr(t.valuesize))
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if t.indirectvalue {
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v = *((*unsafe.Pointer)(v))
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}
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return v
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}
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}
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b = b.overflow(t)
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if b == nil {
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return unsafe.Pointer(t.elem.zero)
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}
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}
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}
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func mapaccess2(t *maptype, h *hmap, key unsafe.Pointer) (unsafe.Pointer, bool) {
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if raceenabled && h != nil {
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callerpc := getcallerpc(unsafe.Pointer(&t))
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pc := funcPC(mapaccess2)
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racereadpc(unsafe.Pointer(h), callerpc, pc)
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raceReadObjectPC(t.key, key, callerpc, pc)
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}
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if h == nil || h.count == 0 {
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return unsafe.Pointer(t.elem.zero), false
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}
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alg := goalg(t.key.alg)
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hash := alg.hash(key, uintptr(t.key.size), uintptr(h.hash0))
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m := uintptr(1)<<h.B - 1
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b := (*bmap)(unsafe.Pointer(uintptr(h.buckets) + (hash&m)*uintptr(t.bucketsize)))
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if c := h.oldbuckets; c != nil {
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oldb := (*bmap)(unsafe.Pointer(uintptr(c) + (hash&(m>>1))*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 := uint8(hash >> (ptrSize*8 - 8))
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if top < minTopHash {
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top += minTopHash
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}
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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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continue
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}
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k := add(unsafe.Pointer(b), dataOffset+i*uintptr(t.keysize))
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if t.indirectkey {
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k = *((*unsafe.Pointer)(k))
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}
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if alg.equal(key, k, uintptr(t.key.size)) {
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v := add(unsafe.Pointer(b), dataOffset+bucketCnt*uintptr(t.keysize)+i*uintptr(t.valuesize))
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if t.indirectvalue {
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v = *((*unsafe.Pointer)(v))
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}
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return v, true
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}
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}
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b = b.overflow(t)
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if b == nil {
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return unsafe.Pointer(t.elem.zero), false
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}
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}
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}
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// returns both key and value. Used by map iterator
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func mapaccessK(t *maptype, h *hmap, key unsafe.Pointer) (unsafe.Pointer, unsafe.Pointer) {
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if h == nil || h.count == 0 {
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return nil, nil
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}
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alg := goalg(t.key.alg)
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hash := alg.hash(key, uintptr(t.key.size), uintptr(h.hash0))
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m := uintptr(1)<<h.B - 1
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b := (*bmap)(unsafe.Pointer(uintptr(h.buckets) + (hash&m)*uintptr(t.bucketsize)))
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if c := h.oldbuckets; c != nil {
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oldb := (*bmap)(unsafe.Pointer(uintptr(c) + (hash&(m>>1))*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 := uint8(hash >> (ptrSize*8 - 8))
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if top < minTopHash {
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top += minTopHash
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}
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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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continue
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}
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k := add(unsafe.Pointer(b), dataOffset+i*uintptr(t.keysize))
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if t.indirectkey {
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k = *((*unsafe.Pointer)(k))
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}
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if alg.equal(key, k, uintptr(t.key.size)) {
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v := add(unsafe.Pointer(b), dataOffset+bucketCnt*uintptr(t.keysize)+i*uintptr(t.valuesize))
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if t.indirectvalue {
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v = *((*unsafe.Pointer)(v))
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}
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return k, v
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}
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}
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b = b.overflow(t)
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if b == nil {
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return nil, nil
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}
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}
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}
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func mapassign1(t *maptype, h *hmap, key unsafe.Pointer, val unsafe.Pointer) {
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if h == nil {
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panic("assignment to entry in nil map")
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}
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if raceenabled {
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callerpc := getcallerpc(unsafe.Pointer(&t))
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pc := funcPC(mapassign1)
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racewritepc(unsafe.Pointer(h), callerpc, pc)
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raceReadObjectPC(t.key, key, callerpc, pc)
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raceReadObjectPC(t.elem, val, callerpc, pc)
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}
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alg := goalg(t.key.alg)
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hash := alg.hash(key, uintptr(t.key.size), uintptr(h.hash0))
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if h.buckets == nil {
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if checkgc {
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memstats.next_gc = memstats.heap_alloc
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}
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h.buckets = newarray(t.bucket, 1)
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}
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again:
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bucket := hash & (uintptr(1)<<h.B - 1)
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if h.oldbuckets != nil {
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growWork(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 := uint8(hash >> (ptrSize*8 - 8))
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if top < minTopHash {
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top += minTopHash
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}
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var inserti *uint8
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var insertk unsafe.Pointer
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var insertv unsafe.Pointer
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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 b.tophash[i] == empty && inserti == nil {
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inserti = &b.tophash[i]
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insertk = add(unsafe.Pointer(b), dataOffset+i*uintptr(t.keysize))
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insertv = add(unsafe.Pointer(b), dataOffset+bucketCnt*uintptr(t.keysize)+i*uintptr(t.valuesize))
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}
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continue
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}
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k := add(unsafe.Pointer(b), dataOffset+i*uintptr(t.keysize))
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k2 := k
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if t.indirectkey {
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k2 = *((*unsafe.Pointer)(k2))
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}
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if !alg.equal(key, k2, uintptr(t.key.size)) {
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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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memmove(k2, key, uintptr(t.key.size))
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v := add(unsafe.Pointer(b), dataOffset+bucketCnt*uintptr(t.keysize)+i*uintptr(t.valuesize))
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v2 := v
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if t.indirectvalue {
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v2 = *((*unsafe.Pointer)(v2))
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}
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memmove(v2, val, uintptr(t.elem.size))
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return
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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 float32(h.count) >= loadFactor*float32((uintptr(1)<<h.B)) && h.count >= bucketCnt {
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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 inserti == nil {
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// all current buckets are full, allocate a new one.
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if checkgc {
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memstats.next_gc = memstats.heap_alloc
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}
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newb := (*bmap)(newobject(t.bucket))
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b.setoverflow(t, newb)
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inserti = &newb.tophash[0]
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insertk = add(unsafe.Pointer(newb), dataOffset)
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insertv = add(insertk, bucketCnt*uintptr(t.keysize))
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}
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|
|
// 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)
|
|
}
|