feat(rust-plugins): rate/delta DSL primitive with persistent state

rust-plugins/Cargo.toml

@@ -7,17 +7,18 @@ edition = "2024"
 lalrpop = "0.23.1"
 
 [dependencies]
-env_logger = "0.11.11"
 lalrpop-util = { version = "0.23.1", features = ["lexer"] }
 lexopt = "0.3.2"
-log = "0.4.33"
 rasn = "0.28.13"
 rasn-smi = "0.28.13"
 rasn-snmp = "0.28.13"
 regex = "1.13.1"
 serde = { version = "1.0.229", features = ["derive"] }
 serde_json = "1.0.151"
 snafu = "0.9.2"
+tracing = "0.1"
+tracing-chrome = "0.7"
+tracing-subscriber = { version = "0.3", features = ["env-filter"] }
 
 [dev-dependencies]
 criterion = { version = "0.8.2", features = ["html_reports"] }

rust-plugins/examples/new-traffic-rate.json

@@ -0,0 +1,35 @@
+{
+  "collect": {
+    "snmp": [
+      {
+        "name": "if",
+        "oid": "1.3.6.1.2.1.2.2.1",
+        "query": "Walk",
+        "labels": {
+          "1.2": "descr",
+          "1.10": "in",
+          "1.16": "out"
+        },
+        "rate": true
+      }
+    ]
+  },
+  "compute": {
+    "metrics": [
+      {
+        "name": "traffic.in.bytespersecond",
+        "value": "{if.in}",
+        "prefix": "{if.descr}",
+        "uom": "B/s",
+        "threshold-suffix": "in"
+      },
+      {
+        "name": "traffic.out.bytespersecond",
+        "value": "{if.out}",
+        "prefix": "{if.descr}",
+        "uom": "B/s",
+        "threshold-suffix": "out"
+      }
+    ]
+  }
+}

rust-plugins/src/compute/ast.rs

@@ -1,8 +1,8 @@
 //! Abstract syntax tree and expression evaluation.
 
 use crate::snmp::SnmpResult;
-use log::{info, trace, warn};
 use std::str;
+use tracing::{info, trace, warn};
 
 /// An expression node in the AST.
 #[derive(Debug)]

rust-plugins/src/compute/lexer.rs

@@ -1,7 +1,7 @@
 //! Lexical analyzer for tokenizing mathematical expressions.
 
-use log::{error, trace};
 use std::str;
+use tracing::{error, trace};
 
 /// Type alias for LALRPOP's expected token type with location and error information.
 pub type Spanned<Tok, Loc, Error> = Result<(Loc, Tok, Loc), Error>;
@@ -177,7 +177,7 @@ mod test {
     use crate::compute::lexer::{Lexer, Tok};
 
     fn init() {
-        let _ = env_logger::builder().is_test(true).try_init();
+        let _ = tracing_subscriber::fmt().with_test_writer().try_init();
     }
 
     #[test]

rust-plugins/src/compute/mod.rs

@@ -12,9 +12,9 @@ use self::ast::ExprResult;
 use self::lexer::{LexicalError, Tok};
 use crate::snmp::SnmpResult;
 use lalrpop_util::{ParseError, lalrpop_mod};
-use log::{debug, trace};
 use regex::Regex;
 use serde::Deserialize;
+use tracing::{debug, trace};
 
 lalrpop_mod!(grammar);
 
@@ -108,7 +108,13 @@ impl<'a> Parser<'a> {
     /// Replaces `{identifier}` with values from SNMP results, handling both
     /// scalar and vector values appropriately.
     pub fn eval_str(&self, expr: &'a str) -> Result<ExprResult, String> {
-        let re = Regex::new(r"\{[a-zA-Z_][a-zA-Z0-9_.]*\}").unwrap();
+        // Compiled once for the whole process: eval_str runs for every
+        // template of every metric, recompiling the regex each time is waste.
+        static MACRO_RE: std::sync::OnceLock<Regex> = std::sync::OnceLock::new();
+        let re = MACRO_RE.get_or_init(|| {
+            // The pattern is a compile-time constant: it cannot fail to build.
+            Regex::new(r"\{[a-zA-Z_][a-zA-Z0-9_.]*\}").expect("static regex")
+        });
         let mut suffix = expr;
         let mut result: ExprResult = ExprResult::Empty;
         trace!("[eval_str] suffix: {:?} - re: {:?}", &suffix, &re);
@@ -153,11 +159,11 @@ impl<'a> Parser<'a> {
 mod test {
     use crate::compute::{Parser, ast::ExprResult, grammar, lexer};
     use crate::snmp::SnmpResult;
-    use log::{debug, info};
     use std::collections::HashMap;
+    use tracing::{debug, info};
 
     fn init() {
-        let _ = env_logger::builder().is_test(true).try_init();
+        let _ = tracing_subscriber::fmt().with_test_writer().try_init();
     }
 
     #[test]

rust-plugins/src/generic/error.rs

@@ -59,6 +59,49 @@ pub enum Error {
     ))]
     FailedToConnectToHost { url: String, os: String },
 
+    #[snafu(display(
+        "SNMP agent returned an error: {} (status {}, index {})",
+        name,
+        status,
+        index
+    ))]
+    SnmpAgentError {
+        name: &'static str,
+        status: u32,
+        index: u32,
+    },
+
+    #[snafu(display("SNMP agent is misbehaving: OID {} is not increasing during walk", oid))]
+    OidNotIncreasing { oid: String },
+
+    #[snafu(display(
+        "SNMP walk aborted: the agent returned more than {} values for a single subtree",
+        max
+    ))]
+    WalkTooLarge { max: usize },
+
+    #[snafu(display("SNMP collection exceeded the global timeout of {}s", seconds))]
+    CollectTimeout { seconds: u64 },
+
+    #[snafu(display(
+        "Could not persist the state file {} ({}): rates would be computed against a stale reference",
+        path,
+        reason
+    ))]
+    StatefileWrite { path: String, reason: String },
+
+    #[snafu(display(
+        "No valid SNMP response from {} after {} attempts (timeout {}s per attempt)",
+        url,
+        attempts,
+        timeout
+    ))]
+    RequestTimeout {
+        url: String,
+        attempts: u32,
+        timeout: u64,
+    },
+
     #[snafu(transparent)]
     Io { source: io::Error },
     #[snafu(transparent)]