Add inplace decimal operations (#10)

* add mutable decimal methods * fix root * gofmt * add Clone(), rm assignment quo * add SetInt64 * fix SetInt64 * More mut speedups Co-authored-by: ValarDragon <[email protected]>
osmosis-labs · Jan 7, 2023 · 44a8b5a · 44a8b5a
1 parent 8c67157
commit 44a8b5a
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Showing 2 changed files with 138 additions and 54 deletions.
diff --git a/types/decimal.go b/types/decimal.go
@@ -212,7 +212,10 @@ func (d Dec) GTE(d2 Dec) bool   { return (d.i).Cmp(d2.i) >= 0 }       // greater
 func (d Dec) LT(d2 Dec) bool    { return (d.i).Cmp(d2.i) < 0 }        // less than
 func (d Dec) LTE(d2 Dec) bool   { return (d.i).Cmp(d2.i) <= 0 }       // less than or equal
 func (d Dec) Neg() Dec          { return Dec{new(big.Int).Neg(d.i)} } // reverse the decimal sign
+func (d Dec) NegMut() Dec       { d.i.Neg(d.i); return d }            // reverse the decimal sign, mutable
 func (d Dec) Abs() Dec          { return Dec{new(big.Int).Abs(d.i)} } // absolute value
+func (d Dec) Set(d2 Dec) Dec    { d.i.Set(d2.i); return d }           // set to existing dec value
+func (d Dec) Clone() Dec        { return Dec{new(big.Int).Set(d.i)} } // clone new dec
 
 // BigInt returns a copy of the underlying big.Int.
 func (d Dec) BigInt() *big.Int {
@@ -224,123 +227,192 @@ func (d Dec) BigInt() *big.Int {
 	return copy.Set(d.i)
 }
 
+func (d Dec) ImmutOp(op func(Dec, Dec) Dec, d2 Dec) Dec {
+	return op(d.Clone(), d2)
+}
+
+func (d Dec) ImmutOpInt(op func(Dec, Int) Dec, d2 Int) Dec {
+	return op(d.Clone(), d2)
+}
+
+func (d Dec) ImmutOpInt64(op func(Dec, int64) Dec, d2 int64) Dec {
+	// TODO: use already allocated operand bigint to avoid
+	// newint each time, add mutex for race condition
+	return op(d.Clone(), d2)
+}
+
+func (d Dec) SetInt64(i int64) Dec {
+	d.i.SetInt64(i)
+	d.i.Mul(d.i, precisionReuse)
+	return d
+}
+
 // addition
 func (d Dec) Add(d2 Dec) Dec {
-	res := new(big.Int).Add(d.i, d2.i)
+	return d.ImmutOp(Dec.AddMut, d2)
+}
+
+// mutable addition
+func (d Dec) AddMut(d2 Dec) Dec {
+	d.i.Add(d.i, d2.i)
 
-	if res.BitLen() > 255+DecimalPrecisionBits {
+	if d.i.BitLen() > 255+DecimalPrecisionBits {
 		panic("Int overflow")
 	}
-	return Dec{res}
+	return d
 }
 
 // subtraction
 func (d Dec) Sub(d2 Dec) Dec {
-	res := new(big.Int).Sub(d.i, d2.i)
+	return d.ImmutOp(Dec.SubMut, d2)
+}
+
+// mutable subtraction
+func (d Dec) SubMut(d2 Dec) Dec {
+	d.i.Sub(d.i, d2.i)
 
-	if res.BitLen() > 255+DecimalPrecisionBits {
+	if d.i.BitLen() > 255+DecimalPrecisionBits {
 		panic("Int overflow")
 	}
-	return Dec{res}
+	return d
 }
 
 // multiplication
 func (d Dec) Mul(d2 Dec) Dec {
-	mul := new(big.Int).Mul(d.i, d2.i)
-	chopped := chopPrecisionAndRound(mul)
+	return d.ImmutOp(Dec.MulMut, d2)
+}
+
+// mutable multiplication
+func (d Dec) MulMut(d2 Dec) Dec {
+	d.i.Mul(d.i, d2.i)
+	chopped := chopPrecisionAndRound(d.i)
 
 	if chopped.BitLen() > 255+DecimalPrecisionBits {
 		panic("Int overflow")
 	}
-	return Dec{chopped}
+	*d.i = *chopped
+	return d
 }
 
 // multiplication truncate
 func (d Dec) MulTruncate(d2 Dec) Dec {
-	mul := new(big.Int).Mul(d.i, d2.i)
-	chopped := chopPrecisionAndTruncate(mul)
+	return d.ImmutOp(Dec.MulTruncateMut, d2)
+}
+
+// mutable multiplication truncage
+func (d Dec) MulTruncateMut(d2 Dec) Dec {
+	d.i.Mul(d.i, d2.i)
+	chopped := chopPrecisionAndTruncate(d.i)
 
 	if chopped.BitLen() > 255+DecimalPrecisionBits {
 		panic("Int overflow")
 	}
-	return Dec{chopped}
+	*d.i = *chopped
+	return d
 }
 
 // multiplication
 func (d Dec) MulInt(i Int) Dec {
-	mul := new(big.Int).Mul(d.i, i.i)
+	return d.ImmutOpInt(Dec.MulIntMut, i)
+}
 
-	if mul.BitLen() > 255+DecimalPrecisionBits {
+func (d Dec) MulIntMut(i Int) Dec {
+	d.i.Mul(d.i, i.i)
+	if d.i.BitLen() > 255+DecimalPrecisionBits {
 		panic("Int overflow")
 	}
-	return Dec{mul}
+	return d
 }
 
 // MulInt64 - multiplication with int64
 func (d Dec) MulInt64(i int64) Dec {
-	mul := new(big.Int).Mul(d.i, big.NewInt(i))
+	return d.ImmutOpInt64(Dec.MulInt64Mut, i)
+}
 
-	if mul.BitLen() > 255+DecimalPrecisionBits {
+func (d Dec) MulInt64Mut(i int64) Dec {
+	d.i.Mul(d.i, big.NewInt(i))
+
+	if d.i.BitLen() > 255+DecimalPrecisionBits {
 		panic("Int overflow")
 	}
-	return Dec{mul}
+	return d
 }
 
 // quotient
 func (d Dec) Quo(d2 Dec) Dec {
-	// multiply precision twice
-	mul := new(big.Int).Mul(d.i, precisionReuse)
-	mul.Mul(mul, precisionReuse)
+	return d.ImmutOp(Dec.QuoMut, d2)
+}
 
-	quo := new(big.Int).Quo(mul, d2.i)
-	chopped := chopPrecisionAndRound(quo)
+// mutable quotient
+func (d Dec) QuoMut(d2 Dec) Dec {
+	// multiply precision twice
+	d.i.Mul(d.i, precisionReuse)
+	d.i.Mul(d.i, precisionReuse)
+	d.i.Quo(d.i, d2.i)
 
-	if chopped.BitLen() > 255+DecimalPrecisionBits {
+	chopPrecisionAndRound(d.i)
+	if d.i.BitLen() > 255+DecimalPrecisionBits {
 		panic("Int overflow")
 	}
-	return Dec{chopped}
+	return d
 }
 
 // quotient truncate
 func (d Dec) QuoTruncate(d2 Dec) Dec {
-	// multiply precision twice
-	mul := new(big.Int).Mul(d.i, precisionReuse)
-	mul.Mul(mul, precisionReuse)
+	return d.ImmutOp(Dec.QuoTruncateMut, d2)
+}
 
-	quo := new(big.Int).Quo(mul, d2.i)
-	chopped := chopPrecisionAndTruncate(quo)
+// mutable quotient truncate
+func (d Dec) QuoTruncateMut(d2 Dec) Dec {
+	// multiply precision twice
+	d.i.Mul(d.i, precisionReuse)
+	d.i.Mul(d.i, precisionReuse)
+	d.i.Quo(d.i, d2.i)
 
-	if chopped.BitLen() > 255+DecimalPrecisionBits {
+	chopPrecisionAndTruncate(d.i)
+	if d.i.BitLen() > 255+DecimalPrecisionBits {
 		panic("Int overflow")
 	}
-	return Dec{chopped}
+	return d
 }
 
 // quotient, round up
 func (d Dec) QuoRoundUp(d2 Dec) Dec {
-	// multiply precision twice
-	mul := new(big.Int).Mul(d.i, precisionReuse)
-	mul.Mul(mul, precisionReuse)
+	return d.ImmutOp(Dec.QuoRoundupMut, d2)
+}
 
-	quo := new(big.Int).Quo(mul, d2.i)
-	chopped := chopPrecisionAndRoundUp(quo)
+// mutable quotient, round up
+func (d Dec) QuoRoundupMut(d2 Dec) Dec {
+	// multiply precision twice
+	d.i.Mul(d.i, precisionReuse)
+	d.i.Mul(d.i, precisionReuse)
+	d.i.Quo(d.i, d2.i)
 
-	if chopped.BitLen() > 255+DecimalPrecisionBits {
+	chopPrecisionAndRoundUp(d.i)
+	if d.i.BitLen() > 255+DecimalPrecisionBits {
 		panic("Int overflow")
 	}
-	return Dec{chopped}
+	return d
 }
 
 // quotient
 func (d Dec) QuoInt(i Int) Dec {
-	mul := new(big.Int).Quo(d.i, i.i)
-	return Dec{mul}
+	return d.ImmutOpInt(Dec.QuoIntMut, i)
+}
+
+func (d Dec) QuoIntMut(i Int) Dec {
+	d.i.Quo(d.i, i.i)
+	return d
 }
 
 // QuoInt64 - quotient with int64
 func (d Dec) QuoInt64(i int64) Dec {
-	mul := new(big.Int).Quo(d.i, big.NewInt(i))
-	return Dec{mul}
+	return d.ImmutOpInt64(Dec.QuoInt64Mut, i)
+}
+
+func (d Dec) QuoInt64Mut(i int64) Dec {
+	d.i.Quo(d.i, big.NewInt(i))
+	return d
 }
 
 // ApproxRoot returns an approximate estimation of a Dec's positive real nth root
@@ -361,8 +433,8 @@ func (d Dec) ApproxRoot(root uint64) (guess Dec, err error) {
 	}()
 
 	if d.IsNegative() {
-		absRoot, err := d.MulInt64(-1).ApproxRoot(root)
-		return absRoot.MulInt64(-1), err
+		absRoot, err := d.Neg().ApproxRoot(root)
+		return absRoot.NegMut(), err
 	}
 
 	if root == 1 || d.IsZero() || d.Equal(OneDec()) {
@@ -373,40 +445,45 @@ func (d Dec) ApproxRoot(root uint64) (guess Dec, err error) {
 		return OneDec(), nil
 	}
 
-	rootInt := NewIntFromUint64(root)
 	guess, delta := OneDec(), OneDec()
 
 	for iter := 0; delta.Abs().GT(SmallestDec()) && iter < maxApproxRootIterations; iter++ {
 		prev := guess.Power(root - 1)
 		if prev.IsZero() {
 			prev = SmallestDec()
 		}
-		delta = d.Quo(prev)
-		delta = delta.Sub(guess)
-		delta = delta.QuoInt(rootInt)
+		delta.Set(d).QuoMut(prev)
+		delta.SubMut(guess)
+		delta.QuoInt64Mut(int64(root))
 
-		guess = guess.Add(delta)
+		guess.AddMut(delta)
 	}
 
 	return guess, nil
 }
 
 // Power returns a the result of raising to a positive integer power
 func (d Dec) Power(power uint64) Dec {
+	res := Dec{new(big.Int).Set(d.i)}
+	return res.PowerMut(power)
+}
+
+func (d Dec) PowerMut(power uint64) Dec {
+	// TODO: use mutable functions here
 	if power == 0 {
 		return OneDec()
 	}
 	tmp := OneDec()
 
 	for i := power; i > 1; {
 		if i%2 != 0 {
-			tmp = tmp.Mul(d)
+			tmp.MulMut(d)
 		}
 		i /= 2
-		d = d.Mul(d)
+		d.MulMut(d)
 	}
 
-	return d.Mul(tmp)
+	return d.MulMut(tmp)
 }
 
 // ApproxSqrt is a wrapper around ApproxRoot for the common special case
@@ -621,7 +698,11 @@ func (d Dec) Ceil() Dec {
 
 // MaxSortableDec is the largest Dec that can be passed into SortableDecBytes()
 // Its negative form is the least Dec that can be passed in.
-var MaxSortableDec = OneDec().Quo(SmallestDec())
+var MaxSortableDec Dec
+
+func init() {
+	MaxSortableDec = OneDec().Quo(SmallestDec())
+}
 
 // ValidSortableDec ensures that a Dec is within the sortable bounds,
 // a Dec can't have a precision of less than 10^-18.

diff --git a/types/decimal_test.go b/types/decimal_test.go
@@ -354,6 +354,9 @@ func (s *decimalTestSuite) TestPower() {
 	for i, tc := range testCases {
 		res := tc.input.Power(tc.power)
 		s.Require().True(tc.expected.Sub(res).Abs().LTE(sdk.SmallestDec()), "unexpected result for test case %d, input: %v", i, tc.input)
+		s.Require().True(tc.expected.Sub(tc.input.PowerMut(tc.power)).Abs().LTE(sdk.SmallestDec()), 
+			"unexpected result for test case %d, input %v", i, tc.input)
+		s.Require().True(res.Equal(tc.input), "unexpected result for test case %d, input: %v", i, tc.input)
 	}
 }