From efd424ebab3b33174233d220866b4bf2c4fae259 Mon Sep 17 00:00:00 2001
From: Matt Jaffee <matthew.jaffee@gmail.com>
Date: Wed, 3 Jul 2019 11:02:59 -0500
Subject: [PATCH] add ability to disable tracing and use nopTracer

Have found some potential performance or stability issues associated
with lots of mutex blocking in getting a parent span's context. Want
the ability to totally disable tracing to help debugging.
---
 cmd/server.go         | 32 +++++++++++++++++---------------
 ctl/server.go         |  2 +-
 docs/configuration.md |  2 +-
 3 files changed, 19 insertions(+), 17 deletions(-)

diff --git a/cmd/server.go b/cmd/server.go
index 6e0e3368a..43432fceb 100644
--- a/cmd/server.go
+++ b/cmd/server.go
@@ -46,22 +46,24 @@ on the configured port.`,
 				return errors.Wrap(err, "running server")
 			}
 
-			// Initialize tracing in the command since it is global.
-			var cfg jaegercfg.Configuration
-			cfg.ServiceName = "pilosa"
-			cfg.Sampler = &jaegercfg.SamplerConfig{
-				Type:  Server.Config.Tracing.SamplerType,
-				Param: Server.Config.Tracing.SamplerParam,
+			if Server.Config.Tracing.SamplerType != "off" {
+				// Initialize tracing in the command since it is global.
+				var cfg jaegercfg.Configuration
+				cfg.ServiceName = "pilosa"
+				cfg.Sampler = &jaegercfg.SamplerConfig{
+					Type:  Server.Config.Tracing.SamplerType,
+					Param: Server.Config.Tracing.SamplerParam,
+				}
+				cfg.Reporter = &jaegercfg.ReporterConfig{
+					LocalAgentHostPort: Server.Config.Tracing.AgentHostPort,
+				}
+				tracer, closer, err := cfg.NewTracer()
+				if err != nil {
+					return errors.Wrap(err, "initializing jaeger tracer")
+				}
+				defer closer.Close()
+				tracing.GlobalTracer = opentracing.NewTracer(tracer)
 			}
-			cfg.Reporter = &jaegercfg.ReporterConfig{
-				LocalAgentHostPort: Server.Config.Tracing.AgentHostPort,
-			}
-			tracer, closer, err := cfg.NewTracer()
-			if err != nil {
-				return errors.Wrap(err, "initializing jaeger tracer")
-			}
-			defer closer.Close()
-			tracing.GlobalTracer = opentracing.NewTracer(tracer)
 
 			return errors.Wrap(Server.Wait(), "waiting on Server")
 		},
diff --git a/ctl/server.go b/ctl/server.go
index ab4dd3305..edeced6b4 100644
--- a/ctl/server.go
+++ b/ctl/server.go
@@ -77,7 +77,7 @@ func BuildServerFlags(cmd *cobra.Command, srv *server.Command) {
 
 	// Tracing
 	flags.StringVarP(&srv.Config.Tracing.AgentHostPort, "tracing.agent-host-port", "", srv.Config.Tracing.AgentHostPort, "Jaeger agent host:port.")
-	flags.StringVarP(&srv.Config.Tracing.SamplerType, "tracing.sampler-type", "", srv.Config.Tracing.SamplerType, "Jaeger sampler type.")
+	flags.StringVarP(&srv.Config.Tracing.SamplerType, "tracing.sampler-type", "", srv.Config.Tracing.SamplerType, "Jaeger sampler type or 'off' to disable tracing completely.")
 	flags.Float64VarP(&srv.Config.Tracing.SamplerParam, "tracing.sampler-param", "", srv.Config.Tracing.SamplerParam, "Jaeger sampler parameter.")
 
 	// Profiling
diff --git a/docs/configuration.md b/docs/configuration.md
index 8eb410de4..9c95f4536 100644
--- a/docs/configuration.md
+++ b/docs/configuration.md
@@ -377,7 +377,7 @@ The config file is in the [toml format](https://github.com/toml-lang/toml) and h
 
 #### Tracing Sampler Type
 
-* Description: Jaeger sampler type (const, probabilistic, ratelimiting, or remote)
+* Description: Jaeger sampler type (const, probabilistic, ratelimiting, or remote). Set to 'off' to disable tracing completely.
 * Flag: `tracing.sampler-type`
 * Env: `PILOSA_TRACING_SAMPLER_TYPE`
 * Config: