LogDog: Update protobufs, add support library.

common/logdog/protocol/butler.proto

Index: common/logdog/protocol/butler.proto
diff --git a/common/logdog/protocol/butler.proto b/common/logdog/protocol/butler.proto
index aaea291e03fa96f3142f0eb4a3291c386823da7f..0faa9619180161032ada78cae74a36c91eead91f 100644
--- a/common/logdog/protocol/butler.proto
+++ b/common/logdog/protocol/butler.proto
@@ -8,6 +8,26 @@ 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
@@ -36,6 +56,22 @@ message ButlerLogBundle {
   optional Timestamp timestamp = 2;
 
   /*
+   * The log prefix'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 = 3;
+
+  /*
    * A bundle Entry describes a set of LogEntry messages originating from the
    * same log stream.
    */
@@ -48,22 +84,6 @@ message ButlerLogBundle {
     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
@@ -78,16 +98,22 @@ message ButlerLogBundle {
     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;
 }