mirror of
https://github.com/ceph/ceph-csi.git
synced 2024-11-23 14:50:24 +00:00
311 lines
7.3 KiB
Go
311 lines
7.3 KiB
Go
/*
|
|
Copyright 2014 The Kubernetes Authors.
|
|
|
|
Licensed under the Apache License, Version 2.0 (the "License");
|
|
you may not use this file except in compliance with the License.
|
|
You may obtain a copy of the License at
|
|
|
|
http://www.apache.org/licenses/LICENSE-2.0
|
|
|
|
Unless required by applicable law or agreed to in writing, software
|
|
distributed under the License is distributed on an "AS IS" BASIS,
|
|
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
See the License for the specific language governing permissions and
|
|
limitations under the License.
|
|
*/
|
|
|
|
package resource
|
|
|
|
import (
|
|
"math/big"
|
|
|
|
inf "gopkg.in/inf.v0"
|
|
)
|
|
|
|
const (
|
|
// maxInt64Factors is the highest value that will be checked when removing factors of 10 from an int64.
|
|
// It is also the maximum decimal digits that can be represented with an int64.
|
|
maxInt64Factors = 18
|
|
)
|
|
|
|
var (
|
|
// Commonly needed big.Int values-- treat as read only!
|
|
bigTen = big.NewInt(10)
|
|
bigZero = big.NewInt(0)
|
|
bigOne = big.NewInt(1)
|
|
bigThousand = big.NewInt(1000)
|
|
big1024 = big.NewInt(1024)
|
|
|
|
// Commonly needed inf.Dec values-- treat as read only!
|
|
decZero = inf.NewDec(0, 0)
|
|
decOne = inf.NewDec(1, 0)
|
|
|
|
// Largest (in magnitude) number allowed.
|
|
maxAllowed = infDecAmount{inf.NewDec((1<<63)-1, 0)} // == max int64
|
|
|
|
// The maximum value we can represent milli-units for.
|
|
// Compare with the return value of Quantity.Value() to
|
|
// see if it's safe to use Quantity.MilliValue().
|
|
MaxMilliValue = int64(((1 << 63) - 1) / 1000)
|
|
)
|
|
|
|
const mostNegative = -(mostPositive + 1)
|
|
const mostPositive = 1<<63 - 1
|
|
|
|
// int64Add returns a+b, or false if that would overflow int64.
|
|
func int64Add(a, b int64) (int64, bool) {
|
|
c := a + b
|
|
switch {
|
|
case a > 0 && b > 0:
|
|
if c < 0 {
|
|
return 0, false
|
|
}
|
|
case a < 0 && b < 0:
|
|
if c > 0 {
|
|
return 0, false
|
|
}
|
|
if a == mostNegative && b == mostNegative {
|
|
return 0, false
|
|
}
|
|
}
|
|
return c, true
|
|
}
|
|
|
|
// int64Multiply returns a*b, or false if that would overflow or underflow int64.
|
|
func int64Multiply(a, b int64) (int64, bool) {
|
|
if a == 0 || b == 0 || a == 1 || b == 1 {
|
|
return a * b, true
|
|
}
|
|
if a == mostNegative || b == mostNegative {
|
|
return 0, false
|
|
}
|
|
c := a * b
|
|
return c, c/b == a
|
|
}
|
|
|
|
// int64MultiplyScale returns a*b, assuming b is greater than one, or false if that would overflow or underflow int64.
|
|
// Use when b is known to be greater than one.
|
|
func int64MultiplyScale(a int64, b int64) (int64, bool) {
|
|
if a == 0 || a == 1 {
|
|
return a * b, true
|
|
}
|
|
if a == mostNegative && b != 1 {
|
|
return 0, false
|
|
}
|
|
c := a * b
|
|
return c, c/b == a
|
|
}
|
|
|
|
// int64MultiplyScale10 multiplies a by 10, or returns false if that would overflow. This method is faster than
|
|
// int64Multiply(a, 10) because the compiler can optimize constant factor multiplication.
|
|
func int64MultiplyScale10(a int64) (int64, bool) {
|
|
if a == 0 || a == 1 {
|
|
return a * 10, true
|
|
}
|
|
if a == mostNegative {
|
|
return 0, false
|
|
}
|
|
c := a * 10
|
|
return c, c/10 == a
|
|
}
|
|
|
|
// int64MultiplyScale100 multiplies a by 100, or returns false if that would overflow. This method is faster than
|
|
// int64Multiply(a, 100) because the compiler can optimize constant factor multiplication.
|
|
func int64MultiplyScale100(a int64) (int64, bool) {
|
|
if a == 0 || a == 1 {
|
|
return a * 100, true
|
|
}
|
|
if a == mostNegative {
|
|
return 0, false
|
|
}
|
|
c := a * 100
|
|
return c, c/100 == a
|
|
}
|
|
|
|
// int64MultiplyScale1000 multiplies a by 1000, or returns false if that would overflow. This method is faster than
|
|
// int64Multiply(a, 1000) because the compiler can optimize constant factor multiplication.
|
|
func int64MultiplyScale1000(a int64) (int64, bool) {
|
|
if a == 0 || a == 1 {
|
|
return a * 1000, true
|
|
}
|
|
if a == mostNegative {
|
|
return 0, false
|
|
}
|
|
c := a * 1000
|
|
return c, c/1000 == a
|
|
}
|
|
|
|
// positiveScaleInt64 multiplies base by 10^scale, returning false if the
|
|
// value overflows. Passing a negative scale is undefined.
|
|
func positiveScaleInt64(base int64, scale Scale) (int64, bool) {
|
|
switch scale {
|
|
case 0:
|
|
return base, true
|
|
case 1:
|
|
return int64MultiplyScale10(base)
|
|
case 2:
|
|
return int64MultiplyScale100(base)
|
|
case 3:
|
|
return int64MultiplyScale1000(base)
|
|
case 6:
|
|
return int64MultiplyScale(base, 1000000)
|
|
case 9:
|
|
return int64MultiplyScale(base, 1000000000)
|
|
default:
|
|
value := base
|
|
var ok bool
|
|
for i := Scale(0); i < scale; i++ {
|
|
if value, ok = int64MultiplyScale(value, 10); !ok {
|
|
return 0, false
|
|
}
|
|
}
|
|
return value, true
|
|
}
|
|
}
|
|
|
|
// negativeScaleInt64 reduces base by the provided scale, rounding up, until the
|
|
// value is zero or the scale is reached. Passing a negative scale is undefined.
|
|
// The value returned, if not exact, is rounded away from zero.
|
|
func negativeScaleInt64(base int64, scale Scale) (result int64, exact bool) {
|
|
if scale == 0 {
|
|
return base, true
|
|
}
|
|
|
|
value := base
|
|
var fraction bool
|
|
for i := Scale(0); i < scale; i++ {
|
|
if !fraction && value%10 != 0 {
|
|
fraction = true
|
|
}
|
|
value = value / 10
|
|
if value == 0 {
|
|
if fraction {
|
|
if base > 0 {
|
|
return 1, false
|
|
}
|
|
return -1, false
|
|
}
|
|
return 0, true
|
|
}
|
|
}
|
|
if fraction {
|
|
if base > 0 {
|
|
value++
|
|
} else {
|
|
value--
|
|
}
|
|
}
|
|
return value, !fraction
|
|
}
|
|
|
|
func pow10Int64(b int64) int64 {
|
|
switch b {
|
|
case 0:
|
|
return 1
|
|
case 1:
|
|
return 10
|
|
case 2:
|
|
return 100
|
|
case 3:
|
|
return 1000
|
|
case 4:
|
|
return 10000
|
|
case 5:
|
|
return 100000
|
|
case 6:
|
|
return 1000000
|
|
case 7:
|
|
return 10000000
|
|
case 8:
|
|
return 100000000
|
|
case 9:
|
|
return 1000000000
|
|
case 10:
|
|
return 10000000000
|
|
case 11:
|
|
return 100000000000
|
|
case 12:
|
|
return 1000000000000
|
|
case 13:
|
|
return 10000000000000
|
|
case 14:
|
|
return 100000000000000
|
|
case 15:
|
|
return 1000000000000000
|
|
case 16:
|
|
return 10000000000000000
|
|
case 17:
|
|
return 100000000000000000
|
|
case 18:
|
|
return 1000000000000000000
|
|
default:
|
|
return 0
|
|
}
|
|
}
|
|
|
|
// negativeScaleInt64 returns the result of dividing base by scale * 10 and the remainder, or
|
|
// false if no such division is possible. Dividing by negative scales is undefined.
|
|
func divideByScaleInt64(base int64, scale Scale) (result, remainder int64, exact bool) {
|
|
if scale == 0 {
|
|
return base, 0, true
|
|
}
|
|
// the max scale representable in base 10 in an int64 is 18 decimal places
|
|
if scale >= 18 {
|
|
return 0, base, false
|
|
}
|
|
divisor := pow10Int64(int64(scale))
|
|
return base / divisor, base % divisor, true
|
|
}
|
|
|
|
// removeInt64Factors divides in a loop; the return values have the property that
|
|
// value == result * base ^ scale
|
|
func removeInt64Factors(value int64, base int64) (result int64, times int32) {
|
|
times = 0
|
|
result = value
|
|
negative := result < 0
|
|
if negative {
|
|
result = -result
|
|
}
|
|
switch base {
|
|
// allow the compiler to optimize the common cases
|
|
case 10:
|
|
for result >= 10 && result%10 == 0 {
|
|
times++
|
|
result = result / 10
|
|
}
|
|
// allow the compiler to optimize the common cases
|
|
case 1024:
|
|
for result >= 1024 && result%1024 == 0 {
|
|
times++
|
|
result = result / 1024
|
|
}
|
|
default:
|
|
for result >= base && result%base == 0 {
|
|
times++
|
|
result = result / base
|
|
}
|
|
}
|
|
if negative {
|
|
result = -result
|
|
}
|
|
return result, times
|
|
}
|
|
|
|
// removeBigIntFactors divides in a loop; the return values have the property that
|
|
// d == result * factor ^ times
|
|
// d may be modified in place.
|
|
// If d == 0, then the return values will be (0, 0)
|
|
func removeBigIntFactors(d, factor *big.Int) (result *big.Int, times int32) {
|
|
q := big.NewInt(0)
|
|
m := big.NewInt(0)
|
|
for d.Cmp(bigZero) != 0 {
|
|
q.DivMod(d, factor, m)
|
|
if m.Cmp(bigZero) != 0 {
|
|
break
|
|
}
|
|
times++
|
|
d, q = q, d
|
|
}
|
|
return d, times
|
|
}
|