From b566773e677a843e50f4093184a6f450000d9854 Mon Sep 17 00:00:00 2001
From: Erik Mackdanz <erikmack@gmail.com>
Date: Wed, 29 Nov 2023 03:13:05 -0600
Subject: [PATCH] Box<dyn Error> not custom error

---
 src/main.rs | 80 ++++++++++-------------------------------------------
 1 file changed, 15 insertions(+), 65 deletions(-)

diff --git a/src/main.rs b/src/main.rs
index b9912bd..2114bf3 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -2,27 +2,10 @@ use aws_sdk_s3::primitives::ByteStream;
 use polars::prelude::*;
 use std::error::Error;
 use std::env::args;
-use std::fmt;
 use std::io::Write;
 use std::fs::{create_dir_all,File};
 
-#[derive(Debug)]
-enum PolarsBOPError {
-    NestedPolarsError(PolarsError),
-    FilesystemError(Box<dyn Error>),
-    S3PutError(Box<dyn Error>),
-    S3GetError(Box<dyn Error>),
-}
-
-impl std::fmt::Display for PolarsBOPError {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-	write!(f, "PolarsBOPError")
-    }
-}
-impl std::error::Error for PolarsBOPError {
-}
-
-async fn map_bucket(partition: &str) -> Result<(),PolarsBOPError> {
+async fn map_bucket(partition: &str) -> Result<(),Box<dyn Error>> {
 
     // set some columns to be parsed as numeric
     let mut schema_override = Schema::new();
@@ -44,16 +27,11 @@ async fn map_bucket(partition: &str) -> Result<(),PolarsBOPError> {
 	)));
 
     // read and parse from disk
-    let df = LazyCsvReader::new("data/bop.csv")
+    let mut df = LazyCsvReader::new("data/bop.csv")
 	.has_header(true)
 	.with_dtype_overwrite(schema_override)
 	.with_null_values(null_values)
-	.finish();
-
-    if let Err(e) = df {
-	return Err(PolarsBOPError::NestedPolarsError(e));
-    };
-    let mut df = df.unwrap();
+	.finish()?;
 
     // split list based on arg
     match partition {
@@ -126,38 +104,26 @@ async fn map_bucket(partition: &str) -> Result<(),PolarsBOPError> {
 	let mask = col("Value").lt(lit(high));
 	df_bucket = df_bucket.filter(mask);
 
-	let df_bucket = df_bucket.collect();
-	if let Err(e) = df_bucket {
-	    return Err(PolarsBOPError::NestedPolarsError(e));
-	}
-	let mut df_bucket = df_bucket.unwrap();
+	let mut df_bucket = df_bucket.collect()?;
 
 	// some console output
 	println!("df_bucket: {:?}",df_bucket);
 
 	// write to local filesystem
-	if let Err(e) = JsonWriter::new(&mut file)
-	    .finish(&mut df_bucket) {
-		return Err(PolarsBOPError::NestedPolarsError(e));
-	    };
+	JsonWriter::new(&mut file)
+	    .finish(&mut df_bucket)?;
 
 	println!("wrote local file {}", outfilepath);
 
 	// open local file for writing to s3
-	let bytes = ByteStream::from_path(outfilepath).await;
-	if let Err(e) = bytes {
-	    return Err(PolarsBOPError::FilesystemError(Box::new(e)));
-	}
-	let bytes = bytes.unwrap();
+	let bytes = ByteStream::from_path(outfilepath).await?;
 
 	// write to s3
-	if let Err(e) = client.put_object()
+	client.put_object()
 	    .bucket("mackdanz-polars-test")
 	    .key(outs3key.clone())
 	    .set_body(Some(bytes))
-	    .send().await {
-		return Err(PolarsBOPError::S3PutError(Box::new(e)));
-	    }
+	    .send().await?;
 
 	println!("wrote file to S3 {}", outs3key);
     }
@@ -165,7 +131,7 @@ async fn map_bucket(partition: &str) -> Result<(),PolarsBOPError> {
     Ok(())
 }
 
-async fn reduce_bucket(bucket: &str) -> Result<(),PolarsBOPError> {
+async fn reduce_bucket(bucket: &str) -> Result<(),Box<dyn Error>> {
     // prep input dir
     let bucketdir = format!("bucket-{}",bucket);
     create_dir_all(format!("out/reducebucket/in/{}",bucketdir.clone()))
@@ -182,11 +148,7 @@ async fn reduce_bucket(bucket: &str) -> Result<(),PolarsBOPError> {
 	let downloadfilepath = format!(
 	    "out/reducebucket/in/bucket-{}/partition-{}.json",
 	    bucket, partition);
-	let downloadfile = File::create(downloadfilepath);
-	if let Err(e) = downloadfile {
-	    return Err(PolarsBOPError::FilesystemError(Box::new(e)));
-	}
-	let mut downloadfile = downloadfile.unwrap();
+	let mut downloadfile = File::create(downloadfilepath)?;
 
 	let ins3key =
 	    format!("mapbucket/bucket-{}/partition-{}.json",
@@ -196,28 +158,16 @@ async fn reduce_bucket(bucket: &str) -> Result<(),PolarsBOPError> {
 	let getobjresult = client.get_object()
 	    .bucket("mackdanz-polars-test")
 	    .key(ins3key.clone())
-	    .send().await;
-
-	if let Err(e) = getobjresult {
-	    return Err(PolarsBOPError::S3GetError(Box::new(e)));
-	}
-	let getobjresult = getobjresult.unwrap();
+	    .send().await?;
 
 	// stream body to local filesystem
 	// https://docs.aws.amazon.com/sdk-for-rust/latest/dg/rust_s3_code_examples.html
 	let mut body = getobjresult.body;
 	loop {
-	    let bytes = body.try_next().await;
-	    if let Err(e) = bytes {
-		return Err(PolarsBOPError::S3GetError(Box::new(e)));
-	    }
-	    let bytes = bytes.unwrap();
+	    let bytes = body.try_next().await?;
 
 	    if let Some(b) = bytes {
-		let writeres = downloadfile.write(&b);
-		if let Err(e) = writeres {
-		    return Err(PolarsBOPError::FilesystemError(Box::new(e)));
-		}
+		let _ = downloadfile.write(&b)?;
 	    } else {
 		break;
 	    }
@@ -232,7 +182,7 @@ async fn reduce_bucket(bucket: &str) -> Result<(),PolarsBOPError> {
 }
 
 #[::tokio::main]
-async fn main() -> Result<(),PolarsBOPError> {
+async fn main() -> Result<(),Box<dyn Error>> {
 
     let mut argsiter = args();
     // first arg is program name
-- 
2.52.0