io error context

src/lib.rs

@@ -21,8 +21,8 @@ pub use win::{get_metrics, Sensors};
 
 #[derive(Debug, thiserror::Error)]
 pub enum Error {
-    #[error(transparent)]
+    #[error("{1}: {0}")]
-    Io(#[from] std::io::Error),
+    Io(std::io::Error, &'static str),
     #[error("{1}: {0}")]
     Os(std::io::Error, &'static str),
     #[error("{0}")]
@@ -55,6 +55,10 @@ impl Error {
         let err = std::io::Error::last_os_error();
         Error::Os(err, context)
     }
+
+    pub fn io(context: &'static str, err: std::io::Error) -> Error {
+        Error::Io(err, context)
+    }
 }
 
 impl From<FromUtf8Error> for Error {
@@ -86,7 +90,18 @@ pub trait MultiSensorSource {
 }
 
 pub fn hostname() -> Result<String> {
-    hostname::get()?
+    hostname::get()
+        .context("error getting hostname")?
         .into_string()
         .map_err(|_| Error::InvalidHostName)
 }
+
+pub trait IoResultExt<T> {
+    fn context(self, context: &'static str) -> Result<T, Error>;
+}
+
+impl<T> IoResultExt<T> for Result<T, std::io::Error> {
+    fn context(self, context: &'static str) -> Result<T, Error> {
+        self.map_err(|e| Error::io(context, e))
+    }
+}

src/linux/disk/mod.rs

@@ -1,5 +1,5 @@
 use crate::data::{DiskStats, DiskUsage};
-use crate::{Error, MultiSensorSource, Result};
+use crate::{Error, IoResultExt, MultiSensorSource, Result};
 use ahash::{AHashSet, AHasher};
 use regex::Regex;
 use std::ffi::CString;
@@ -20,7 +20,7 @@ pub struct DiskStatSource {
 impl DiskStatSource {
     pub fn new() -> Result<DiskStatSource> {
         Ok(DiskStatSource {
-            source: File::open("/proc/diskstats")?,
+            source: File::open("/proc/diskstats").context("error getting disk stats")?,
             buff: String::new(),
             regex: Regex::new(r" ([sv]d[a-z]+|nvme[0-9]n[0-9]|mmcblk[0-9]) ").unwrap(),
         })
@@ -33,8 +33,10 @@ impl MultiSensorSource for DiskStatSource {
 
     fn read(&mut self) -> Result<Self::Iter<'_>> {
         self.buff.clear();
-        self.source.rewind()?;
+        self.source.rewind().context("error rewinding disk stats")?;
-        self.source.read_to_string(&mut self.buff)?;
+        self.source
+            .read_to_string(&mut self.buff)
+            .context("error reading disk stats")?;
 
         Ok(DiskStatParser {
             lines: self.buff.lines(),
@@ -83,7 +85,7 @@ pub struct DiskUsageSource {
 impl DiskUsageSource {
     pub fn new() -> Result<DiskUsageSource> {
         Ok(DiskUsageSource {
-            source: File::open("/proc/mounts")?,
+            source: File::open("/proc/mounts").context("error opening mounts")?,
             buff: String::new(),
         })
     }
@@ -95,8 +97,10 @@ impl MultiSensorSource for DiskUsageSource {
 
     fn read(&mut self) -> Result<Self::Iter<'_>> {
         self.buff.clear();
-        self.source.rewind()?;
+        self.source.rewind().context("error rewinding mounts")?;
-        self.source.read_to_string(&mut self.buff)?;
+        self.source
+            .read_to_string(&mut self.buff)
+            .context("error reading mounts")?;
 
         Ok(DiskUsageParser {
             lines: self.buff.lines(),

src/linux/disk/zfs.rs

@@ -1,5 +1,5 @@
 use crate::linux::disk::DiskUsage;
-use crate::Result;
+use crate::{IoResultExt, Result};
 use std::fmt::Write;
 use std::fs::read_to_string;
 use std::process::Command;
@@ -23,7 +23,7 @@ pub fn pools() -> impl Iterator<Item = DiskUsage> {
 fn zpool_command() -> Result<String> {
     let mut z = Command::new("zpool");
     z.args(["list", "-p", "-H", "-o", "name,size,free"]);
-    let out = z.output()?;
+    let out = z.output().context("error getting zpool list")?;
     if out.status.success() {
         Ok(String::from_utf8(out.stdout)?)
     } else {
@@ -111,10 +111,10 @@ impl ArcStats {
     }
 }
 
-pub fn arcstats() -> Result<Option<ArcStats>> {
+pub fn arcstats() -> Option<ArcStats> {
     let content = match read_to_string("/proc/spl/kstat/zfs/arcstats") {
         Ok(c) => c,
-        Err(_) => return Ok(None),
+        Err(_) => return None,
     };
     let mut stats = ArcStats::default();
 
@@ -150,5 +150,5 @@ pub fn arcstats() -> Result<Option<ArcStats>> {
         }
     }
 
-    Ok(Some(stats))
+    Some(stats)
 }

src/linux/mod.rs

@@ -112,7 +112,7 @@ pub fn get_metrics(sensors: &Sensors) -> Result<String> {
 
     cpu_power.write(&mut result, &sensors.hostname);
     gpu_power.write(&mut result, &sensors.hostname);
-    if let Some(arc) = arcstats()? {
+    if let Some(arc) = arcstats() {
         arc.write(&mut result, &sensors.hostname);
     }
     if let Some(memory) = gpu::memory() {

src/linux/power.rs

@@ -1,7 +1,7 @@
 use crate::data::{CpuPowerUsage, GpuPowerUsage};
 use crate::linux::gpu::gpu_power;
 use crate::linux::hwmon::FileSource;
-use crate::{Result, SensorSource};
+use crate::{IoResultExt, Result, SensorSource};
 use std::fs::read_dir;
 
 #[derive(Default)]
@@ -11,7 +11,8 @@ pub struct CpuPowerSource {
 
 impl CpuPowerSource {
     pub fn new() -> Result<CpuPowerSource> {
-        let sources: Vec<_> = read_dir("/sys/devices/virtual/powercap/intel-rapl")?
+        let sources: Vec<_> = read_dir("/sys/devices/virtual/powercap/intel-rapl")
+            .context("error listing power devices")?
             .flatten()
             .filter(|path| {
                 path.file_name()
@@ -37,7 +38,7 @@ impl SensorSource for CpuPowerSource {
     fn read(&mut self) -> Result<Self::Data> {
         let mut usage = CpuPowerUsage::default();
         for source in self.sources.iter_mut() {
-            let package_usage = source.read()?;
+            let package_usage = source.read().context("error reading power source")?;
             usage.cpu_uj += package_usage;
             usage.cpu_packages_uj.push(package_usage);
         }

src/linux/sensors.rs

@@ -1,6 +1,6 @@
 use crate::data::{CpuTime, Memory, NetStats, Temperatures};
 use crate::linux::hwmon::{Device, FileSource};
-use crate::{Error, MultiSensorSource, Result, SensorSource};
+use crate::{Error, IoResultExt, MultiSensorSource, Result, SensorSource};
 use std::fs::File;
 use std::io;
 use std::io::{BufRead, BufReader, ErrorKind, Read, Seek};
@@ -23,7 +23,7 @@ impl TemperatureSource {
             {
                 for sensor in device.sensors().flatten() {
                     if sensor.name() == "Tdie" || sensor.name().starts_with("Core ") {
-                        cpu_sensors.push(sensor.reader()?);
+                        cpu_sensors.push(sensor.reader().context("error opening cpu temp sensor")?);
                     }
                 }
             }
@@ -31,7 +31,7 @@ impl TemperatureSource {
             if device.name() == "amdgpu" || device.name() == "gpu_thermal" {
                 for sensor in device.sensors().flatten() {
                     if sensor.name() == "edge" {
-                        gpu_sensors.push(sensor.reader()?);
+                        gpu_sensors.push(sensor.reader().context("error opening gpu temp sensor")?);
                     }
                 }
             }
@@ -85,7 +85,7 @@ pub struct MemorySource {
 impl MemorySource {
     pub fn new() -> Result<MemorySource> {
         Ok(MemorySource {
-            source: File::open("/proc/meminfo")?,
+            source: File::open("/proc/meminfo").context("error opening meminfo")?,
             buff: String::new(),
         })
     }
@@ -96,8 +96,10 @@ impl SensorSource for MemorySource {
 
     fn read(&mut self) -> Result<Self::Data> {
         self.buff.clear();
-        self.source.rewind()?;
+        self.source.rewind().context("error rewdinging meminfo")?;
-        self.source.read_to_string(&mut self.buff)?;
+        self.source
+            .read_to_string(&mut self.buff)
+            .context("error reading meminfo")?;
 
         let mut mem = Memory::default();
         for line in self.buff.lines() {
@@ -127,7 +129,7 @@ pub struct CpuTimeSource {
 impl CpuTimeSource {
     pub fn new() -> Result<CpuTimeSource> {
         Ok(CpuTimeSource {
-            source: BufReader::new(File::open("/proc/stat")?),
+            source: BufReader::new(File::open("/proc/stat").context("error opening proc stats")?),
             buff: Vec::new(),
             cpu_count: sysconf(SysconfVariable::ScNprocessorsOnln)? as f32,
         })
@@ -139,9 +141,11 @@ impl SensorSource for CpuTimeSource {
 
     fn read(&mut self) -> Result<Self::Data> {
         self.buff.clear();
-        self.source.rewind()?;
+        self.source.rewind().context("error rewinding proc")?;
 
-        self.source.read_until(b'\n', &mut self.buff)?;
+        self.source
+            .read_until(b'\n', &mut self.buff)
+            .context("error reading proc")?;
 
         let line = std::str::from_utf8(&self.buff)?;
 
@@ -156,7 +160,10 @@ impl SensorSource for CpuTimeSource {
                 (user + system) / (clock_ticks as f32) / self.cpu_count,
             ))
         } else {
-            Err(io::Error::from(ErrorKind::InvalidData).into())
+            Err(Error::io(
+                "invalid proc data",
+                io::Error::from(ErrorKind::InvalidData),
+            ))
         }
     }
 }
@@ -169,7 +176,7 @@ pub struct NetworkSource {
 impl NetworkSource {
     pub fn new() -> Result<NetworkSource> {
         Ok(NetworkSource {
-            source: File::open("/proc/net/dev")?,
+            source: File::open("/proc/net/dev").context("error opening netdev")?,
             buff: String::new(),
         })
     }
@@ -205,7 +212,10 @@ impl NetworkSource {
                 bytes_received: bytes_received.parse()?,
             })
         } else {
-            Err(Error::Io(ErrorKind::InvalidData.into()))
+            Err(Error::io(
+                "error reading netdev",
+                ErrorKind::InvalidData.into(),
+            ))
         }
     }
 }
@@ -216,8 +226,10 @@ impl MultiSensorSource for NetworkSource {
 
     fn read(&mut self) -> Result<Self::Iter<'_>> {
         self.buff.clear();
-        self.source.rewind()?;
+        self.source.rewind().context("error rewinding netdev")?;
-        self.source.read_to_string(&mut self.buff)?;
+        self.source
+            .read_to_string(&mut self.buff)
+            .context("error reading netdev")?;
 
         Ok(NetworkStatParser {
             lines: self.buff.lines(),