| // Copyright 2018 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 |
| |
| import ( |
| "runtime/internal/sys" |
| "unsafe" |
| ) |
| |
| // For gccgo, use go:linkname to export compiler-called functions. |
| // |
| //go:linkname mapaccess1_faststr |
| //go:linkname mapaccess2_faststr |
| //go:linkname mapassign_faststr |
| //go:linkname mapdelete_faststr |
| |
| func mapaccess1_faststr(t *maptype, h *hmap, ky string) unsafe.Pointer { |
| if raceenabled && h != nil { |
| callerpc := getcallerpc() |
| racereadpc(unsafe.Pointer(h), callerpc, funcPC(mapaccess1_faststr)) |
| } |
| if h == nil || h.count == 0 { |
| return unsafe.Pointer(&zeroVal[0]) |
| } |
| if h.flags&hashWriting != 0 { |
| throw("concurrent map read and map write") |
| } |
| key := stringStructOf(&ky) |
| if h.B == 0 { |
| // One-bucket table. |
| b := (*bmap)(h.buckets) |
| if key.len < 32 { |
| // short key, doing lots of comparisons is ok |
| for i, kptr := uintptr(0), b.keys(); i < bucketCnt; i, kptr = i+1, add(kptr, 2*sys.PtrSize) { |
| k := (*stringStruct)(kptr) |
| if k.len != key.len || isEmpty(b.tophash[i]) { |
| if b.tophash[i] == emptyRest { |
| break |
| } |
| continue |
| } |
| if k.str == key.str || memequal(k.str, key.str, uintptr(key.len)) { |
| return add(unsafe.Pointer(b), dataOffset+bucketCnt*2*sys.PtrSize+i*uintptr(t.elemsize)) |
| } |
| } |
| return unsafe.Pointer(&zeroVal[0]) |
| } |
| // long key, try not to do more comparisons than necessary |
| keymaybe := uintptr(bucketCnt) |
| for i, kptr := uintptr(0), b.keys(); i < bucketCnt; i, kptr = i+1, add(kptr, 2*sys.PtrSize) { |
| k := (*stringStruct)(kptr) |
| if k.len != key.len || isEmpty(b.tophash[i]) { |
| if b.tophash[i] == emptyRest { |
| break |
| } |
| continue |
| } |
| if k.str == key.str { |
| return add(unsafe.Pointer(b), dataOffset+bucketCnt*2*sys.PtrSize+i*uintptr(t.elemsize)) |
| } |
| // check first 4 bytes |
| if *((*[4]byte)(key.str)) != *((*[4]byte)(k.str)) { |
| continue |
| } |
| // check last 4 bytes |
| if *((*[4]byte)(add(key.str, uintptr(key.len)-4))) != *((*[4]byte)(add(k.str, uintptr(key.len)-4))) { |
| continue |
| } |
| if keymaybe != bucketCnt { |
| // Two keys are potential matches. Use hash to distinguish them. |
| goto dohash |
| } |
| keymaybe = i |
| } |
| if keymaybe != bucketCnt { |
| k := (*stringStruct)(add(unsafe.Pointer(b), dataOffset+keymaybe*2*sys.PtrSize)) |
| if memequal(k.str, key.str, uintptr(key.len)) { |
| return add(unsafe.Pointer(b), dataOffset+bucketCnt*2*sys.PtrSize+keymaybe*uintptr(t.elemsize)) |
| } |
| } |
| return unsafe.Pointer(&zeroVal[0]) |
| } |
| dohash: |
| hash := t.hasher(noescape(unsafe.Pointer(&ky)), uintptr(h.hash0)) |
| m := bucketMask(h.B) |
| b := (*bmap)(add(h.buckets, (hash&m)*uintptr(t.bucketsize))) |
| if c := h.oldbuckets; c != nil { |
| if !h.sameSizeGrow() { |
| // There used to be half as many buckets; mask down one more power of two. |
| m >>= 1 |
| } |
| oldb := (*bmap)(add(c, (hash&m)*uintptr(t.bucketsize))) |
| if !evacuated(oldb) { |
| b = oldb |
| } |
| } |
| top := tophash(hash) |
| for ; b != nil; b = b.overflow(t) { |
| for i, kptr := uintptr(0), b.keys(); i < bucketCnt; i, kptr = i+1, add(kptr, 2*sys.PtrSize) { |
| k := (*stringStruct)(kptr) |
| if k.len != key.len || b.tophash[i] != top { |
| continue |
| } |
| if k.str == key.str || memequal(k.str, key.str, uintptr(key.len)) { |
| return add(unsafe.Pointer(b), dataOffset+bucketCnt*2*sys.PtrSize+i*uintptr(t.elemsize)) |
| } |
| } |
| } |
| return unsafe.Pointer(&zeroVal[0]) |
| } |
| |
| func mapaccess2_faststr(t *maptype, h *hmap, ky string) (unsafe.Pointer, bool) { |
| if raceenabled && h != nil { |
| callerpc := getcallerpc() |
| racereadpc(unsafe.Pointer(h), callerpc, funcPC(mapaccess2_faststr)) |
| } |
| if h == nil || h.count == 0 { |
| return unsafe.Pointer(&zeroVal[0]), false |
| } |
| if h.flags&hashWriting != 0 { |
| throw("concurrent map read and map write") |
| } |
| key := stringStructOf(&ky) |
| if h.B == 0 { |
| // One-bucket table. |
| b := (*bmap)(h.buckets) |
| if key.len < 32 { |
| // short key, doing lots of comparisons is ok |
| for i, kptr := uintptr(0), b.keys(); i < bucketCnt; i, kptr = i+1, add(kptr, 2*sys.PtrSize) { |
| k := (*stringStruct)(kptr) |
| if k.len != key.len || isEmpty(b.tophash[i]) { |
| if b.tophash[i] == emptyRest { |
| break |
| } |
| continue |
| } |
| if k.str == key.str || memequal(k.str, key.str, uintptr(key.len)) { |
| return add(unsafe.Pointer(b), dataOffset+bucketCnt*2*sys.PtrSize+i*uintptr(t.elemsize)), true |
| } |
| } |
| return unsafe.Pointer(&zeroVal[0]), false |
| } |
| // long key, try not to do more comparisons than necessary |
| keymaybe := uintptr(bucketCnt) |
| for i, kptr := uintptr(0), b.keys(); i < bucketCnt; i, kptr = i+1, add(kptr, 2*sys.PtrSize) { |
| k := (*stringStruct)(kptr) |
| if k.len != key.len || isEmpty(b.tophash[i]) { |
| if b.tophash[i] == emptyRest { |
| break |
| } |
| continue |
| } |
| if k.str == key.str { |
| return add(unsafe.Pointer(b), dataOffset+bucketCnt*2*sys.PtrSize+i*uintptr(t.elemsize)), true |
| } |
| // check first 4 bytes |
| if *((*[4]byte)(key.str)) != *((*[4]byte)(k.str)) { |
| continue |
| } |
| // check last 4 bytes |
| if *((*[4]byte)(add(key.str, uintptr(key.len)-4))) != *((*[4]byte)(add(k.str, uintptr(key.len)-4))) { |
| continue |
| } |
| if keymaybe != bucketCnt { |
| // Two keys are potential matches. Use hash to distinguish them. |
| goto dohash |
| } |
| keymaybe = i |
| } |
| if keymaybe != bucketCnt { |
| k := (*stringStruct)(add(unsafe.Pointer(b), dataOffset+keymaybe*2*sys.PtrSize)) |
| if memequal(k.str, key.str, uintptr(key.len)) { |
| return add(unsafe.Pointer(b), dataOffset+bucketCnt*2*sys.PtrSize+keymaybe*uintptr(t.elemsize)), true |
| } |
| } |
| return unsafe.Pointer(&zeroVal[0]), false |
| } |
| dohash: |
| hash := t.hasher(noescape(unsafe.Pointer(&ky)), uintptr(h.hash0)) |
| m := bucketMask(h.B) |
| b := (*bmap)(add(h.buckets, (hash&m)*uintptr(t.bucketsize))) |
| if c := h.oldbuckets; c != nil { |
| if !h.sameSizeGrow() { |
| // There used to be half as many buckets; mask down one more power of two. |
| m >>= 1 |
| } |
| oldb := (*bmap)(add(c, (hash&m)*uintptr(t.bucketsize))) |
| if !evacuated(oldb) { |
| b = oldb |
| } |
| } |
| top := tophash(hash) |
| for ; b != nil; b = b.overflow(t) { |
| for i, kptr := uintptr(0), b.keys(); i < bucketCnt; i, kptr = i+1, add(kptr, 2*sys.PtrSize) { |
| k := (*stringStruct)(kptr) |
| if k.len != key.len || b.tophash[i] != top { |
| continue |
| } |
| if k.str == key.str || memequal(k.str, key.str, uintptr(key.len)) { |
| return add(unsafe.Pointer(b), dataOffset+bucketCnt*2*sys.PtrSize+i*uintptr(t.elemsize)), true |
| } |
| } |
| } |
| return unsafe.Pointer(&zeroVal[0]), false |
| } |
| |
| func mapassign_faststr(t *maptype, h *hmap, s string) unsafe.Pointer { |
| if h == nil { |
| panic(plainError("assignment to entry in nil map")) |
| } |
| if raceenabled { |
| callerpc := getcallerpc() |
| racewritepc(unsafe.Pointer(h), callerpc, funcPC(mapassign_faststr)) |
| } |
| if h.flags&hashWriting != 0 { |
| throw("concurrent map writes") |
| } |
| key := stringStructOf(&s) |
| hash := t.hasher(noescape(unsafe.Pointer(&s)), uintptr(h.hash0)) |
| |
| // Set hashWriting after calling t.hasher for consistency with mapassign. |
| h.flags ^= hashWriting |
| |
| if h.buckets == nil { |
| h.buckets = newobject(t.bucket) // newarray(t.bucket, 1) |
| } |
| |
| again: |
| bucket := hash & bucketMask(h.B) |
| if h.growing() { |
| growWork_faststr(t, h, bucket) |
| } |
| b := (*bmap)(add(h.buckets, bucket*uintptr(t.bucketsize))) |
| top := tophash(hash) |
| |
| var insertb *bmap |
| var inserti uintptr |
| var insertk unsafe.Pointer |
| |
| bucketloop: |
| for { |
| for i := uintptr(0); i < bucketCnt; i++ { |
| if b.tophash[i] != top { |
| if isEmpty(b.tophash[i]) && insertb == nil { |
| insertb = b |
| inserti = i |
| } |
| if b.tophash[i] == emptyRest { |
| break bucketloop |
| } |
| continue |
| } |
| k := (*stringStruct)(add(unsafe.Pointer(b), dataOffset+i*2*sys.PtrSize)) |
| if k.len != key.len { |
| continue |
| } |
| if k.str != key.str && !memequal(k.str, key.str, uintptr(key.len)) { |
| continue |
| } |
| // already have a mapping for key. Update it. |
| inserti = i |
| insertb = b |
| goto done |
| } |
| ovf := b.overflow(t) |
| if ovf == nil { |
| break |
| } |
| b = ovf |
| } |
| |
| // Did not find mapping for key. Allocate new cell & add entry. |
| |
| // If we hit the max load factor or we have too many overflow buckets, |
| // and we're not already in the middle of growing, start growing. |
| if !h.growing() && (overLoadFactor(h.count+1, h.B) || tooManyOverflowBuckets(h.noverflow, h.B)) { |
| hashGrow(t, h) |
| goto again // Growing the table invalidates everything, so try again |
| } |
| |
| if insertb == nil { |
| // The current bucket and all the overflow buckets connected to it are full, allocate a new one. |
| insertb = h.newoverflow(t, b) |
| inserti = 0 // not necessary, but avoids needlessly spilling inserti |
| } |
| insertb.tophash[inserti&(bucketCnt-1)] = top // mask inserti to avoid bounds checks |
| |
| insertk = add(unsafe.Pointer(insertb), dataOffset+inserti*2*sys.PtrSize) |
| // store new key at insert position |
| *((*stringStruct)(insertk)) = *key |
| h.count++ |
| |
| done: |
| elem := add(unsafe.Pointer(insertb), dataOffset+bucketCnt*2*sys.PtrSize+inserti*uintptr(t.elemsize)) |
| if h.flags&hashWriting == 0 { |
| throw("concurrent map writes") |
| } |
| h.flags &^= hashWriting |
| return elem |
| } |
| |
| func mapdelete_faststr(t *maptype, h *hmap, ky string) { |
| if raceenabled && h != nil { |
| callerpc := getcallerpc() |
| racewritepc(unsafe.Pointer(h), callerpc, funcPC(mapdelete_faststr)) |
| } |
| if h == nil || h.count == 0 { |
| return |
| } |
| if h.flags&hashWriting != 0 { |
| throw("concurrent map writes") |
| } |
| |
| key := stringStructOf(&ky) |
| hash := t.hasher(noescape(unsafe.Pointer(&ky)), uintptr(h.hash0)) |
| |
| // Set hashWriting after calling t.hasher for consistency with mapdelete |
| h.flags ^= hashWriting |
| |
| bucket := hash & bucketMask(h.B) |
| if h.growing() { |
| growWork_faststr(t, h, bucket) |
| } |
| b := (*bmap)(add(h.buckets, bucket*uintptr(t.bucketsize))) |
| bOrig := b |
| top := tophash(hash) |
| search: |
| for ; b != nil; b = b.overflow(t) { |
| for i, kptr := uintptr(0), b.keys(); i < bucketCnt; i, kptr = i+1, add(kptr, 2*sys.PtrSize) { |
| k := (*stringStruct)(kptr) |
| if k.len != key.len || b.tophash[i] != top { |
| continue |
| } |
| if k.str != key.str && !memequal(k.str, key.str, uintptr(key.len)) { |
| continue |
| } |
| // Clear key's pointer. |
| k.str = nil |
| e := add(unsafe.Pointer(b), dataOffset+bucketCnt*2*sys.PtrSize+i*uintptr(t.elemsize)) |
| if t.elem.ptrdata != 0 { |
| memclrHasPointers(e, t.elem.size) |
| } else { |
| memclrNoHeapPointers(e, t.elem.size) |
| } |
| b.tophash[i] = emptyOne |
| // If the bucket now ends in a bunch of emptyOne states, |
| // change those to emptyRest states. |
| if i == bucketCnt-1 { |
| if b.overflow(t) != nil && b.overflow(t).tophash[0] != emptyRest { |
| goto notLast |
| } |
| } else { |
| if b.tophash[i+1] != emptyRest { |
| goto notLast |
| } |
| } |
| for { |
| b.tophash[i] = emptyRest |
| if i == 0 { |
| if b == bOrig { |
| break // beginning of initial bucket, we're done. |
| } |
| // Find previous bucket, continue at its last entry. |
| c := b |
| for b = bOrig; b.overflow(t) != c; b = b.overflow(t) { |
| } |
| i = bucketCnt - 1 |
| } else { |
| i-- |
| } |
| if b.tophash[i] != emptyOne { |
| break |
| } |
| } |
| notLast: |
| h.count-- |
| // Reset the hash seed to make it more difficult for attackers to |
| // repeatedly trigger hash collisions. See issue 25237. |
| if h.count == 0 { |
| h.hash0 = fastrand() |
| } |
| break search |
| } |
| } |
| |
| if h.flags&hashWriting == 0 { |
| throw("concurrent map writes") |
| } |
| h.flags &^= hashWriting |
| } |
| |
| func growWork_faststr(t *maptype, h *hmap, bucket uintptr) { |
| // make sure we evacuate the oldbucket corresponding |
| // to the bucket we're about to use |
| evacuate_faststr(t, h, bucket&h.oldbucketmask()) |
| |
| // evacuate one more oldbucket to make progress on growing |
| if h.growing() { |
| evacuate_faststr(t, h, h.nevacuate) |
| } |
| } |
| |
| func evacuate_faststr(t *maptype, h *hmap, oldbucket uintptr) { |
| b := (*bmap)(add(h.oldbuckets, oldbucket*uintptr(t.bucketsize))) |
| newbit := h.noldbuckets() |
| if !evacuated(b) { |
| // TODO: reuse overflow buckets instead of using new ones, if there |
| // is no iterator using the old buckets. (If !oldIterator.) |
| |
| // xy contains the x and y (low and high) evacuation destinations. |
| var xy [2]evacDst |
| x := &xy[0] |
| x.b = (*bmap)(add(h.buckets, oldbucket*uintptr(t.bucketsize))) |
| x.k = add(unsafe.Pointer(x.b), dataOffset) |
| x.e = add(x.k, bucketCnt*2*sys.PtrSize) |
| |
| if !h.sameSizeGrow() { |
| // Only calculate y pointers if we're growing bigger. |
| // Otherwise GC can see bad pointers. |
| y := &xy[1] |
| y.b = (*bmap)(add(h.buckets, (oldbucket+newbit)*uintptr(t.bucketsize))) |
| y.k = add(unsafe.Pointer(y.b), dataOffset) |
| y.e = add(y.k, bucketCnt*2*sys.PtrSize) |
| } |
| |
| for ; b != nil; b = b.overflow(t) { |
| k := add(unsafe.Pointer(b), dataOffset) |
| e := add(k, bucketCnt*2*sys.PtrSize) |
| for i := 0; i < bucketCnt; i, k, e = i+1, add(k, 2*sys.PtrSize), add(e, uintptr(t.elemsize)) { |
| top := b.tophash[i] |
| if isEmpty(top) { |
| b.tophash[i] = evacuatedEmpty |
| continue |
| } |
| if top < minTopHash { |
| throw("bad map state") |
| } |
| var useY uint8 |
| if !h.sameSizeGrow() { |
| // Compute hash to make our evacuation decision (whether we need |
| // to send this key/elem to bucket x or bucket y). |
| hash := t.hasher(k, uintptr(h.hash0)) |
| if hash&newbit != 0 { |
| useY = 1 |
| } |
| } |
| |
| b.tophash[i] = evacuatedX + useY // evacuatedX + 1 == evacuatedY, enforced in makemap |
| dst := &xy[useY] // evacuation destination |
| |
| if dst.i == bucketCnt { |
| dst.b = h.newoverflow(t, dst.b) |
| dst.i = 0 |
| dst.k = add(unsafe.Pointer(dst.b), dataOffset) |
| dst.e = add(dst.k, bucketCnt*2*sys.PtrSize) |
| } |
| dst.b.tophash[dst.i&(bucketCnt-1)] = top // mask dst.i as an optimization, to avoid a bounds check |
| |
| // Copy key. |
| *(*string)(dst.k) = *(*string)(k) |
| |
| typedmemmove(t.elem, dst.e, e) |
| dst.i++ |
| // These updates might push these pointers past the end of the |
| // key or elem arrays. That's ok, as we have the overflow pointer |
| // at the end of the bucket to protect against pointing past the |
| // end of the bucket. |
| dst.k = add(dst.k, 2*sys.PtrSize) |
| dst.e = add(dst.e, uintptr(t.elemsize)) |
| } |
| } |
| // 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) |
| } |
| } |