logdog: Add bundler library.

client/internal/logdog/butler/bundler/doc.go

+// Copyright 2015 The Chromium 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 bundler exports the Bundler interface and its implementation, as well
+// as supporting interfaces.
+//
+// A Bundler is responsible for efficiently buffering and clustering LogDog
+// Butler protobufs together for output. It is primarily focused on two
+// protobufs:
+//   - The ButlerLogBundle_Entry, which represents a series of logs and
+//     metadata belonging to a single stream.
+//   - The LogEntry, which is a single chunk of unqualified log data.
+//
+// These protobufs comprise log data, and are grouped together for export in
+// a ButlerLogBundle protobuf.
+//
+// A ButlerLogBundle_Entry will be exported if it matches ANY of the following
+// conditions:
+//   - It has attached log data.
+//   - It has terminal information.
+//
+// Since LogDog outputs can be size-constrained, the Bundler tracks the expected
+// aggregate buffered protobuf size and, on export, breaks the buffered
+// protobufs into bundles along a size threshold boundary.
+package bundler