92 lines
2.8 KiB
Go
92 lines
2.8 KiB
Go
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// mgo - MongoDB driver for Go
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//
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// Copyright (c) 2010-2012 - Gustavo Niemeyer <gustavo@niemeyer.net>
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//
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// All rights reserved.
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//
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are met:
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//
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// 1. Redistributions of source code must retain the above copyright notice, this
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// list of conditions and the following disclaimer.
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// 2. Redistributions in binary form must reproduce the above copyright notice,
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// this list of conditions and the following disclaimer in the documentation
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// and/or other materials provided with the distribution.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
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// ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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// WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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// DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
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// ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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// (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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// LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
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// ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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package mgo
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type queue struct {
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elems []interface{}
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nelems, popi, pushi int
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}
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func (q *queue) Len() int {
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return q.nelems
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}
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func (q *queue) Push(elem interface{}) {
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//debugf("Pushing(pushi=%d popi=%d cap=%d): %#v\n",
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// q.pushi, q.popi, len(q.elems), elem)
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if q.nelems == len(q.elems) {
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q.expand()
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}
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q.elems[q.pushi] = elem
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q.nelems++
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q.pushi = (q.pushi + 1) % len(q.elems)
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//debugf(" Pushed(pushi=%d popi=%d cap=%d): %#v\n",
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// q.pushi, q.popi, len(q.elems), elem)
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}
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func (q *queue) Pop() (elem interface{}) {
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//debugf("Popping(pushi=%d popi=%d cap=%d)\n",
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// q.pushi, q.popi, len(q.elems))
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if q.nelems == 0 {
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return nil
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}
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elem = q.elems[q.popi]
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q.elems[q.popi] = nil // Help GC.
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q.nelems--
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q.popi = (q.popi + 1) % len(q.elems)
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//debugf(" Popped(pushi=%d popi=%d cap=%d): %#v\n",
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// q.pushi, q.popi, len(q.elems), elem)
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return elem
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}
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func (q *queue) expand() {
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curcap := len(q.elems)
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var newcap int
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if curcap == 0 {
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newcap = 8
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} else if curcap < 1024 {
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newcap = curcap * 2
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} else {
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newcap = curcap + (curcap / 4)
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}
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elems := make([]interface{}, newcap)
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if q.popi == 0 {
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copy(elems, q.elems)
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q.pushi = curcap
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} else {
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newpopi := newcap - (curcap - q.popi)
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copy(elems, q.elems[:q.popi])
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copy(elems[newpopi:], q.elems[q.popi:])
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q.popi = newpopi
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}
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for i := range q.elems {
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q.elems[i] = nil // Help GC.
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}
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q.elems = elems
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}
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