interface.go

// Copyright (c) 2014 Ashley Jeffs
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.

package impl

import "github.com/Jeffail/benthos/lib/types"

//------------------------------------------------------------------------------

// Buffer represents a method of storing messages.
type Buffer interface {
	// ShiftMessage removes the oldest message from the stack. Returns the
	// backlog in bytes.
	ShiftMessage() (int, error)

	// NextMessage reads the oldest message, the message is preserved until
	// ShiftMessage is called.
	NextMessage() (types.Message, error)

	// PushMessage adds a new message to the stack. Returns the backlog in
	// bytes.
	PushMessage(types.Message) (int, error)

	// CloseOnceEmpty closes the Buffer once the buffer has been emptied, this
	// is a way for a writer to signal to a reader that it is finished writing
	// messages, and therefore the reader can close once it is caught up. This
	// call blocks until the close is completed.
	CloseOnceEmpty()

	// Close closes the Buffer so that blocked readers or writers become
	// unblocked.
	Close()
}

//------------------------------------------------------------------------------