LogDog: Update protobufs, add support library.

common/logdog/protocol/butler.proto

 // 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 protocol;
 
 import "log.proto";
 import "types.proto";
 
 /*
+ * ButlerMetadata appears as a frame at the beginning of Butler published data
+ * to describe the remainder of the contents.
+ */
+message ButlerMetadata {
+        /*
+         * This enumerates the possible contents of published Butler data.
+         */
+        enum ContentType {
+                /* The published data is a ButlerLogBundle protobuf message. */
+                ButlerLogBundle = 1;
+        }
+        /* This is the type of data in the subsequent frame. */
+        optional ContentType type = 1;
+
+        /* If true, the content data is compressed. */
+        optional bool compressed = 2;
+}
+
+
+/*
  * A message containing log data in transit from the Butler.
  *
  * The Butler is capable of conserving bandwidth by bundling collected log
  * messages together into this protocol buffer. Based on Butler bundling
  * settings, this message can represent anything from a single LogRecord to
  * multiple LogRecords belonging to several different streams.
  *
  * Entries in a Log Bundle are fully self-descriptive: no additional information
  * is needed to fully associate the contained data with its proper place in
  * the source log stream.
  */
 message ButlerLogBundle {
   /*
    * String describing the source of this LogBundle.
    * This is an unstructured field, and is not intended to be parsed. An
    * example would be: "Butler @a33967 (Linux/amd64)".
    *
    * This field will be used for debugging and internal accounting.
    */
   optional string source = 1;
 
   /* The timestamp when this bundle was generated.
    *
    * This field will be used for debugging and internal accounting.
    */
   optional Timestamp timestamp = 2;
 
   /*
+   * The log stream's secret value (required).

[iannucci, 2015/08/26 18:33:33]

log prefix's

+   *
+   * The secret is generated by the Butler and unique to this specific log
+   * stream. The Coordinator will record the secret associated with a given
+   * log Prefix/Stream, but will not share the secret with a client.
+   *
+   * The Collector will check the secret prior to ingesting logs. If the
+   * secret doesn't match the value recorded by the Coordinator, the log
+   * will be discarded.
+   *
+   * This ensures that only the Butler instance that generated the log stream
+   * can emit log data for that stream.
+   */
+  optional bytes secret = 3;
+
+  /*
    * A bundle Entry describes a set of LogEntry messages originating from the
    * same log stream.
    */
   message Entry {
     /*
      * The descriptor for this entry's log stream.
      *
      * Each LogEntry in the "logs" field is shares this common descriptor.
      */
     optional LogStreamDescriptor desc = 1;
 
     /*
-     * The log stream's secret value (required).
-     *
-     * The secret is generated by the Butler and unique to this specific log
-     * stream. The Coordinator will record the secret associated with a given
-     * log Prefix/Stream, but will not share the secret with a client.
-     *
-     * The Collector will check the secret prior to ingesting logs. If the
-     * secret doesn't match the value recorded by the Coordinator, the log
-     * will be discarded.
-     *
-     * This ensures that only the Butler instance that generated the log stream
-     * can emit log data for that stream.
-     */
-    optional bytes secret = 2;
-
-    /*
      * Whether this log entry terminates its stream.
      *
      * If present and "true", this field declares that this Entry is the last
      * such entry in the stream. This fact is recorded by the Collector and
      * registered with the Coordinator. The largest stream prefix in this Entry
      * will be bound the stream's LogEntry records to [0:largest_prefix]. Once
      * all messages in that range have been received, the log may be archived.
      *
      * Further log entries belonging to this stream with stream indices
      * exceeding the terminal log's index will be discarded.
      */
     optional bool terminal = 3;
 
     /*
+     * If terminal is true, this is the terminal stream index; that is, the last
+     * message index in the stream.
+     */
+    optional uint32 terminal_index = 4;
+
+    /*
      * Log entries attached to this record. These must be sequential and in
      * order.
      *
      * This is the main log entry content.
      */
-    repeated protocol.LogEntry logs = 4;
+    repeated protocol.LogEntry logs = 5;
   }
 
   /**
    * Each Entry is an individual set of log records for a given log stream.
    */
-  repeated Entry entries = 5;
+  repeated Entry entries = 4;
 }