github.com/bir3/gocompiler@v0.9.2202/src/internal/fuzz/queue.go (about) 1 // Copyright 2021 The Go Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style 3 // license that can be found in the LICENSE file. 4 5 package fuzz 6 7 // queue holds a growable sequence of inputs for fuzzing and minimization. 8 // 9 // For now, this is a simple ring buffer 10 // (https://en.wikipedia.org/wiki/Circular_buffer). 11 // 12 // TODO(golang.org/issue/46224): use a prioritization algorithm based on input 13 // size, previous duration, coverage, and any other metrics that seem useful. 14 type queue struct { 15 // elems holds a ring buffer. 16 // The queue is empty when begin = end. 17 // The queue is full (until grow is called) when end = begin + N - 1 (mod N) 18 // where N = cap(elems). 19 elems []any 20 head, len int 21 } 22 23 func (q *queue) cap() int { 24 return len(q.elems) 25 } 26 27 func (q *queue) grow() { 28 oldCap := q.cap() 29 newCap := oldCap * 2 30 if newCap == 0 { 31 newCap = 8 32 } 33 newElems := make([]any, newCap) 34 oldLen := q.len 35 for i := 0; i < oldLen; i++ { 36 newElems[i] = q.elems[(q.head+i)%oldCap] 37 } 38 q.elems = newElems 39 q.head = 0 40 } 41 42 func (q *queue) enqueue(e any) { 43 if q.len+1 > q.cap() { 44 q.grow() 45 } 46 i := (q.head + q.len) % q.cap() 47 q.elems[i] = e 48 q.len++ 49 } 50 51 func (q *queue) dequeue() (any, bool) { 52 if q.len == 0 { 53 return nil, false 54 } 55 e := q.elems[q.head] 56 q.elems[q.head] = nil 57 q.head = (q.head + 1) % q.cap() 58 q.len-- 59 return e, true 60 } 61 62 func (q *queue) peek() (any, bool) { 63 if q.len == 0 { 64 return nil, false 65 } 66 return q.elems[q.head], true 67 } 68 69 func (q *queue) clear() { 70 *q = queue{} 71 }