dep -> govendor

vendor/github.com/go-gl/mathgl/mgl64/mempool.go

@@ -0,0 +1,123 @@
+// This file is generated from mgl32/mempool.go; DO NOT EDIT
+
+// Copyright 2014 The go-gl 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 mgl64
+
+import (
+	"sync"
+)
+
+var (
+	slicePools []*sync.Pool
+	listLock   sync.RWMutex
+)
+
+var shouldPool = true
+
+func DisableMemoryPooling() {
+	shouldPool = false
+}
+
+// Returns the given memory pool. If the pool doesn't exist, it will
+// create all pools up to element i. The number "i" corresponds to "p"
+// in most other comments. That is, it's Ceil(log_2(whatever)). So i=0
+// means you'll get the pool for slices of size 1, i=1 for size 2, i=2 for size 4,
+// and so on.
+//
+// This is concurrency safe and uses an RWMutex to protect the list expansion.
+func getPool(i int) *sync.Pool {
+	listLock.RLock()
+	if i >= len(slicePools) {
+
+		// Promote to a write lock because we now
+		// need to mutate the pool
+		listLock.RUnlock()
+		listLock.Lock()
+		defer listLock.Unlock()
+
+		for n := i - len(slicePools); n >= 0; n-- {
+			newFunc := genPoolNew(1 << uint(len(slicePools)))
+			slicePools = append(slicePools, &sync.Pool{New: newFunc})
+		}
+	} else {
+		defer listLock.RUnlock()
+	}
+
+	return slicePools[i]
+}
+
+func genPoolNew(i int) func() interface{} {
+	return func() interface{} {
+		return make([]float64, 0, i)
+	}
+}
+
+// Grabs a slice from the memory pool, such that its cap
+// is 2^p where p is Ceil(log_2(size)). It will be downsliced
+// such that the len is size.
+func grabFromPool(size int) []float64 {
+	pool, exact := binLog(size)
+
+	// Tried to grab something of size
+	// zero or less
+	if pool == -1 {
+		return nil
+	}
+
+	// If the log is not exact, we
+	// need to "overallocate" so we have
+	// log+1
+	if !exact {
+		pool++
+	}
+
+	slice := getPool(pool).Get().([]float64)
+	slice = slice[:size]
+	return slice
+}
+
+// Returns a slice to the appropriate pool. If the slice does not have a cap that's precisely
+// a power of 2, this will panic.
+func returnToPool(slice []float64) {
+	if cap(slice) == 0 {
+		return
+	}
+
+	pool, exact := binLog(cap(slice))
+
+	if !exact {
+		panic("attempt to pool slice with non-exact cap. If you're a user, please file an issue with github.com/go-gl/mathgl about this bug. This should never happen.")
+	}
+
+	getPool(pool).Put(slice)
+}
+
+// This returns the integer base 2 log of the value
+// and whether the log is exact or rounded down.
+//
+// This is only for positive integers.
+//
+// There are faster ways to do this, I'm open to suggestions. Most rely on knowing system endianness
+// which Go makes hard to do. I'm hesistant to use float conversions and the math package because of off-by-one errors.
+func binLog(val int) (int, bool) {
+	if val <= 0 {
+		return -1, false
+	}
+
+	exact := true
+	l := 0
+	for ; val > 1; val = val >> 1 {
+		// If the current lsb is 1 and the number
+		// is not equal to 1, this is not an exact
+		// log, but rather a rounding of it
+		if val&1 != 0 {
+			exact = false
+		}
+		l++
+	}
+
+	return l, exact
+}