feat: Add print to stdout to data generator (#2512)

This adds a flag to the data generator to print samples to standard out. It disables logging output so that only the line protocol is output.

iox_data_generator/src/bin/iox_data_generator.rs

@@ -18,8 +18,6 @@ use tracing::info;
 
 #[tokio::main]
 async fn main() -> Result<(), Box<dyn std::error::Error>> {
-    tracing_subscriber::fmt::init();
-
     let help = r#"IOx data point generator
 
 Examples:
@@ -60,6 +58,10 @@ Logging:
                 .takes_value(true)
                 .required(true),
         )
+        .arg(Arg::with_name("PRINT")
+                .long("print")
+            .help("Print the generated line protocol from a single sample collection to the terminal")
+        )
         .arg(
             Arg::with_name("OUTPUT")
                 .short("o")
@@ -135,6 +137,11 @@ Logging:
         )
         .get_matches();
 
+    let disable_log_output = matches.is_present("PRINT");
+    if !disable_log_output {
+        tracing_subscriber::fmt::init();
+    }
+
     let spec_filename = matches
         .value_of("SPECIFICATION")
         // This should never fail if clap is working properly
@@ -181,8 +188,10 @@ Logging:
         );
 
         PointsWriterBuilder::new_api(host, org, bucket, token, create_bucket, org_id).await?
+    } else if matches.is_present("PRINT") {
+        PointsWriterBuilder::new_std_out()
     } else {
-        panic!("One of --output or --host must be provided.");
+        panic!("One of --print or --output or --host must be provided.");
     };
 
     let result = iox_data_generator::generate::<rand::rngs::SmallRng>(
@@ -197,7 +206,11 @@ Logging:
     .await;
 
     match result {
-        Ok(total_points) => eprintln!("Submitted {} total points", total_points),
+        Ok(total_points) => {
+            if !disable_log_output {
+                eprintln!("Submitted {} total points", total_points);
+            }
+        }
         Err(e) => panic!("Execution failed: \n{}", e),
     }
 

iox_data_generator/src/write.rs

@@ -95,6 +95,7 @@ enum PointsWriterConfig {
     },
     #[cfg(test)]
     Vector(BTreeMap<String, Arc<Mutex<Vec<u8>>>>),
+    Stdout,
 }
 
 impl PointsWriterBuilder {
@@ -157,6 +158,13 @@ impl PointsWriterBuilder {
         })
     }
 
+    /// Write points to stdout
+    pub fn new_std_out() -> Self {
+        Self {
+            config: PointsWriterConfig::Stdout,
+        }
+    }
+
     /// Generate points but do not write them anywhere
     pub fn new_no_op(perform_write: bool) -> Self {
         Self {
@@ -193,6 +201,7 @@ impl PointsWriterBuilder {
                     .or_insert_with(|| Arc::new(Mutex::new(Vec::new())));
                 InnerPointsWriter::Vec(Arc::clone(v))
             }
+            PointsWriterConfig::Stdout => InnerPointsWriter::Stdout,
         };
 
         PointsWriter { inner_writer }
@@ -225,6 +234,7 @@ enum InnerPointsWriter {
     },
     #[cfg(test)]
     Vec(Arc<Mutex<Vec<u8>>>),
+    Stdout,
 }
 
 impl InnerPointsWriter {
@@ -278,6 +288,13 @@ impl InnerPointsWriter {
                         .expect("Should be able to write to vec");
                 }
             }
+            Self::Stdout => {
+                for point in points {
+                    point
+                        .write_data_point_to(std::io::stdout())
+                        .expect("should be able to write to stdout");
+                }
+            }
         }
         Ok(())
     }