concurrent_slice.go

// Copyright (c) 2015-2017 Marin Atanasov Nikolov <dnaeon@gmail.com>
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions
// are met:
//
//  1. Redistributions of source code must retain the above copyright
//     notice, this list of conditions and the following disclaimer
//     in this position and unchanged.
//  2. Redistributions in binary form must reproduce the above copyright
//     notice, this list of conditions and the following disclaimer in the
//     documentation and/or other materials provided with the distribution.
//
// THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) ``AS IS'' AND ANY EXPRESS OR
// IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
// OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
// IN NO EVENT SHALL THE AUTHOR(S) BE LIABLE FOR ANY DIRECT, INDIRECT,
// INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
// NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
// THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

package utils

import "sync"

// ConcurrentSlice type that can be safely shared between goroutines
type ConcurrentSlice struct {
	sync.RWMutex
	items []interface{}
}

// ConcurrentSliceItem contains the index/value pair of an item in a
// concurrent slice
type ConcurrentSliceItem struct {
	Index int
	Value interface{}
}

// NewConcurrentSlice creates a new concurrent slice
func NewConcurrentSlice() *ConcurrentSlice {
	cs := &ConcurrentSlice{
		items: make([]interface{}, 0),
	}

	return cs
}

// Append adds an item to the concurrent slice
func (cs *ConcurrentSlice) Append(item interface{}) {
	cs.Lock()
	defer cs.Unlock()

	cs.items = append(cs.items, item)
}

// Len returns the number of items in the concurrent slice
func (cs *ConcurrentSlice) Len() int {
	cs.Lock()
	defer cs.Unlock()
	return len(cs.items)
}

// Iter iterates over the items in the concurrent slice
// Each item is sent over a channel, so that
// we can iterate over the slice using the builin range keyword
func (cs *ConcurrentSlice) Iter() <-chan ConcurrentSliceItem {
	c := make(chan ConcurrentSliceItem)

	f := func() {
		cs.Lock()
		defer cs.Unlock()
		for index, value := range cs.items {
			c <- ConcurrentSliceItem{index, value}
		}
		close(c)
	}
	go f()

	return c
}