Fix sparse index handling, add index params.

logdog/api/logpb/log.pb.go

Index: logdog/api/logpb/log.pb.go
diff --git a/logdog/api/logpb/log.pb.go b/logdog/api/logpb/log.pb.go
index d266d491c52a8ac001b0292a50c120a18dcd3a50..627de9abd881a49397d33c7f536c3bfe5eaab093 100644
--- a/logdog/api/logpb/log.pb.go
+++ b/logdog/api/logpb/log.pb.go
@@ -412,6 +412,24 @@ type LogIndex struct {
 	// The frequency of Entry messages is not defined; it is up to the Archivist
 	// process to choose a frequency.
 	Entries []*LogIndex_Entry `protobuf:"bytes,2,rep,name=entries" json:"entries,omitempty"`
+	// *
+	// The last prefix index in the log stream.
+	//
+	// This is optional. If zero, there is either no information about the last
+	// prefix index, or there are zero entries in the prefix.
+	LastPrefixIndex uint64 `protobuf:"varint,3,opt,name=last_prefix_index,json=lastPrefixIndex" json:"last_prefix_index,omitempty"`
+	// *
+	// The last stream index in the log stream.
+	//
+	// This is optional. If zero, there is either no information about the last
+	// stream index, or there are zero entries in the stream.
+	LastStreamIndex uint64 `protobuf:"varint,4,opt,name=last_stream_index,json=lastStreamIndex" json:"last_stream_index,omitempty"`
+	// *
+	// The number of log entries in the stream.
+	//
+	// This is optional. If zero, there is either no information about the number
+	// of log entries, or there are zero entries in the stream.
+	LogEntryCount uint64 `protobuf:"varint,5,opt,name=log_entry_count,json=logEntryCount" json:"log_entry_count,omitempty"`
 }
 
 func (m *LogIndex) Reset()                    { *m = LogIndex{} }
@@ -501,50 +519,54 @@ func init() {
 func init() { proto.RegisterFile("github.com/luci/luci-go/logdog/api/logpb/log.proto", fileDescriptor1) }
 
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