/usr/share/gocode/src/github.com/streadway/amqp/allocator.go is in golang-github-streadway-amqp-dev 0.0~git20150820.0.f4879ba-6.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 | package amqp
import (
"bytes"
"fmt"
"math/big"
)
const (
free = 0
allocated = 1
)
// allocator maintains a bitset of allocated numbers.
type allocator struct {
pool *big.Int
last int
low int
high int
}
// NewAllocator reserves and frees integers out of a range between low and
// high.
//
// O(N) worst case space used, where N is maximum allocated, divided by
// sizeof(big.Word)
func newAllocator(low, high int) *allocator {
return &allocator{
pool: big.NewInt(0),
last: low,
low: low,
high: high,
}
}
// String returns a string describing the contents of the allocator like
// "allocator[low..high] reserved..until"
//
// O(N) where N is high-low
func (a allocator) String() string {
b := &bytes.Buffer{}
fmt.Fprintf(b, "allocator[%d..%d]", a.low, a.high)
for low := a.low; low <= a.high; low++ {
high := low
for a.reserved(high) && high <= a.high {
high++
}
if high > low+1 {
fmt.Fprintf(b, " %d..%d", low, high-1)
} else if high > low {
fmt.Fprintf(b, " %d", high-1)
}
low = high
}
return b.String()
}
// Next reserves and returns the next available number out of the range between
// low and high. If no number is available, false is returned.
//
// O(N) worst case runtime where N is allocated, but usually O(1) due to a
// rolling index into the oldest allocation.
func (a *allocator) next() (int, bool) {
wrapped := a.last
// Find trailing bit
for ; a.last <= a.high; a.last++ {
if a.reserve(a.last) {
return a.last, true
}
}
// Find preceeding free'd pool
a.last = a.low
for ; a.last < wrapped; a.last++ {
if a.reserve(a.last) {
return a.last, true
}
}
return 0, false
}
// reserve claims the bit if it is not already claimed, returning true if
// succesfully claimed.
func (a *allocator) reserve(n int) bool {
if a.reserved(n) {
return false
}
a.pool.SetBit(a.pool, n-a.low, allocated)
return true
}
// reserved returns true if the integer has been allocated
func (a *allocator) reserved(n int) bool {
return a.pool.Bit(n-a.low) == allocated
}
// release frees the use of the number for another allocation
func (a *allocator) release(n int) {
a.pool.SetBit(a.pool, n-a.low, free)
}
|