enh(generic-snmp): custom error introduced. It is used for thresholds but should be generalized

experimental/Cargo.toml

@@ -16,3 +16,4 @@ rasn-snmp = "0.26.2"
 regex = "1.11.1"
 serde = { version = "1.0.219", features = ["derive"] }
 serde_json = "1.0.140"
+snafu = "0.8.5"

experimental/src/compute/threshold.rs

@@ -1,6 +1,6 @@
-use std::f64::INFINITY;
-
+use generic::error::Error;
 use log::{debug, error, info, trace, warn};
+use std::f64::INFINITY;
 
 pub struct Threshold {
     start: f64,
@@ -8,12 +8,12 @@ pub struct Threshold {
 }
 
 impl Threshold {
-    pub fn parse(expr: &str) -> Threshold {
+    pub fn parse(expr: &str) -> Result<Threshold, Error> {
         // https://nagios-plugins.org/doc/guidelines.html#THRESHOLDFORMAT
         let mut start: usize = 0;
         let mut in_number = false;
-        let mut start_value = -INFINITY;
-        let mut end_value = INFINITY;
+        let mut current = 0;
+        let mut value = [-INFINITY, INFINITY];
         let mut in_range = false;
         for (idx, c) in expr.char_indices() {
             if in_number {
@@ -22,7 +22,7 @@ impl Threshold {
                     '.' | '-' | '+' | 'e' | 'E' => continue,
                     _ => {
                         in_number = false;
-                        start_value = match expr[start..idx].parse() {
+                        value[current] = match expr[start..idx].parse() {
                             Ok(x) => x,
                             Err(err) => {
                                 error!("parse error: {}", err);
@@ -40,15 +40,19 @@ impl Threshold {
                         in_number = true;
                         start = idx;
                     }
+                    '~' => {
+                        value[0] = -INFINITY;
+                    }
                     ':' => {
                         in_range = true;
+                        current = 1;
                     }
                     _ => break,
                 }
             }
         }
         if in_number {
-            start_value = match expr[start..].parse() {
+            value[current] = match expr[start..].parse() {
                 Ok(x) => x,
                 Err(err) => {
                     error!("parse error: {}", err);
@@ -59,15 +63,24 @@ impl Threshold {
 
         /* We have noticed a ':' character, so the threshold is a range */
         if in_range {
-            return Threshold {
-                start: start_value,
-                end: INFINITY,
-            };
+            if value[0] > value[1] {
+                return Err(Error::BadThresholdRange {
+                    start: value[0],
+                    end: value[1],
+                });
+            }
+            return Ok(Threshold {
+                start: value[0],
+                end: value[1],
+            });
         } else {
-            return Threshold {
+            if value[0] <= 0_f64 {
+                return Err(Error::NegativeSimpleThreshold { value: value[0] });
+            }
+            return Ok(Threshold {
                 start: 0_f64,
-                end: start_value,
-            };
+                end: value[0],
+            });
         }
     }
 
@@ -86,20 +99,88 @@ mod Test {
     fn test_parse_value() {
         let expr = "1.2";
         let threshold = Threshold::parse(expr);
-        assert_eq!(threshold.start, 0_f64);
-        assert_eq!(threshold.end, 1.2_f64);
-        assert!(threshold.in_alert(2_f64));
-        assert!(threshold.in_alert(-1_f64));
+        match threshold {
+            Ok(threshold) => {
+                assert_eq!(threshold.start, 0_f64);
+                assert_eq!(threshold.end, 1.2_f64);
+                assert!(threshold.in_alert(2_f64));
+                assert!(threshold.in_alert(-1_f64));
+            }
+            Err(err) => {
+                panic!("We should not have this error here: {}", err);
+            }
+        }
     }
 
     #[test]
     fn test_parse_val_colon() {
         let expr = "10:";
         let threshold = Threshold::parse(expr);
-        assert_eq!(threshold.start, 10_f64);
-        assert_eq!(threshold.end, INFINITY);
-        assert!(!threshold.in_alert(10_f64));
-        assert!(!threshold.in_alert(11_f64));
-        assert!(threshold.in_alert(9_f64));
+        match threshold {
+            Ok(threshold) => {
+                assert_eq!(threshold.start, 10_f64);
+                assert_eq!(threshold.end, INFINITY);
+                assert!(!threshold.in_alert(10_f64));
+                assert!(!threshold.in_alert(11_f64));
+                assert!(threshold.in_alert(9_f64));
+            }
+            Err(err) => {
+                panic!("We should not have this error here: {}", err);
+            }
+        }
+    }
+
+    #[test]
+    fn test_parse_tilda_val() {
+        let expr = "~:10";
+        let threshold = Threshold::parse(expr);
+        match threshold {
+            Ok(threshold) => {
+                assert_eq!(threshold.start, -INFINITY);
+                assert_eq!(threshold.end, 10_f64);
+                assert!(!threshold.in_alert(10_f64));
+                assert!(threshold.in_alert(11_f64));
+                assert!(!threshold.in_alert(9_f64));
+            }
+            Err(err) => {
+                panic!("We should not have this error here: {}", err);
+            }
+        }
+    }
+
+    #[test]
+    fn test_parse_val_val() {
+        let expr = "10:20";
+        let threshold = Threshold::parse(expr);
+        match threshold {
+            Ok(threshold) => {
+                assert_eq!(threshold.start, 10_f64);
+                assert_eq!(threshold.end, 20_f64);
+                assert!(!threshold.in_alert(10_f64));
+                assert!(!threshold.in_alert(11_f64));
+                assert!(threshold.in_alert(9_f64));
+                assert!(threshold.in_alert(21_f64));
+            }
+            Err(err) => {
+                panic!("We should not have this error here: {}", err);
+            }
+        }
+    }
+
+    #[test]
+    fn test_parse_bad_val_val() {
+        let expr = "30:20";
+        let threshold = Threshold::parse(expr);
+        match threshold {
+            Ok(_) => {
+                panic!("The thrshold '{}' should not be valid", expr);
+            }
+            Err(err) => {
+                assert_eq!(
+                    err.to_string(),
+                    "The start value 30 must be less than the end value 20"
+                );
+            }
+        }
     }
 }

experimental/src/generic/error.rs

@@ -0,0 +1,35 @@
+use snafu::prelude::*;
+use std::{fs, io, path::PathBuf};
+
+#[derive(Debug, Snafu)]
+pub enum Error {
+    #[snafu(display(
+        "This syntax is a shortcut of '0:{}', so {} must be greater than 0.",
+        value,
+        value
+    ))]
+    NegativeSimpleThreshold { value: f64 },
+
+    #[snafu(display("The start value {} must be less than the end value {}", start, end))]
+    BadThresholdRange { start: f64, end: f64 },
+
+    #[snafu(display("Unable to read configuration from {}", path.display()))]
+    ReadConfiguration { source: io::Error, path: PathBuf },
+
+    #[snafu(display("Unable to write result to {}", path.display()))]
+    WriteResult { source: io::Error, path: PathBuf },
+}
+
+type Result<T, E = Error> = std::result::Result<T, E>;
+
+fn process_data() -> Result<()> {
+    let path = "config.toml";
+    let configuration = fs::read_to_string(path).context(ReadConfigurationSnafu { path })?;
+    let path = unpack_config(&configuration);
+    fs::write(&path, b"My complex calculation").context(WriteResultSnafu { path })?;
+    Ok(())
+}
+
+fn unpack_config(data: &str) -> &str {
+    "/some/path/that/does/not/exist"
+}

experimental/src/generic/mod.rs

@@ -1,6 +1,8 @@
 extern crate serde;
 extern crate serde_json;
 
+pub mod error;
+
 use compute::{ast::ExprResult, threshold::Threshold, Compute, Parser};
 use log::{debug, trace};
 use serde::Deserialize;

experimental/src/main.rs

@@ -8,6 +8,7 @@ extern crate rasn_snmp;
 extern crate regex;
 extern crate serde;
 extern crate serde_json;
+extern crate snafu;
 
 mod compute;
 mod generic;
@@ -18,7 +19,6 @@ use lalrpop_util::lalrpop_mod;
 use lexopt::Arg;
 use log::{debug, trace};
 use serde_json::Result;
-use std::collections::HashMap;
 use std::fs;
 
 lalrpop_mod!(grammar);