mmoxi 0.3.1

//! `mmlspool` parsing.

#![deny(clippy::all)]
#![warn(clippy::pedantic, clippy::nursery, clippy::cargo)]

use std::io::Write;
use std::process::Command;
use std::str::FromStr;

use anyhow::{anyhow, Context, Result};

// ----------------------------------------------------------------------------
// CLI interface
// ----------------------------------------------------------------------------

/// Runs `mmlspool` on the given filesystem, and returns the parsed output.
///
/// # Errors
///
/// Returns an error if running `mmlspool` fails or if parsing its output
/// fails.
pub fn run(fs_name: &str) -> Result<Filesystem> {
    let mut cmd = Command::new("mmlspool");
    cmd.arg(fs_name);

    let output = cmd
        .output()
        .with_context(|| format!("error running: {cmd:?}"))?;

    if output.status.success() {
        let output = String::from_utf8(output.stdout).with_context(|| {
            format!("parsing {cmd:?} command output to UTF8")
        })?;

        let pools = parse_mmlspool_output(&output)
            .context("parsing pools to internal data")?;

        Ok(Filesystem {
            name: fs_name.into(),
            pools,
        })
    } else {
        Err(anyhow!("error running: {:?}", cmd))
    }
}

/// Runs `mmlspool` on all given filesystems, and returns the parsed output.
///
/// # Errors
///
/// Returns an error if running `mmlspool` fails or if parsing its output
/// fails.
pub fn run_all<S>(fs_names: &[S]) -> Result<Vec<Filesystem>>
where
    S: AsRef<str>,
{
    let mut filesystems = Vec::with_capacity(fs_names.len());

    for fs in fs_names {
        let filesystem = run(fs.as_ref())?;
        filesystems.push(filesystem);
    }

    Ok(filesystems)
}

// ----------------------------------------------------------------------------
// data structures and parsing
// ----------------------------------------------------------------------------

/// A file system.
#[derive(Clone, Eq, PartialEq, Ord, PartialOrd, Hash, Debug, Default)]
pub struct Filesystem {
    name: String,
    pools: Vec<Pool>,
}

impl Filesystem {
    /// Returns the file system name.
    #[must_use]
    pub fn name(&self) -> &str {
        &self.name
    }

    /// Returns the pools.
    #[must_use]
    pub fn pools(&self) -> &[Pool] {
        &self.pools
    }
}

/// Pool size.
#[derive(
    Copy, Clone, Eq, PartialEq, Ord, PartialOrd, Hash, Debug, Default,
)]
pub struct Size {
    total_kb: u64,
    free_kb: u64,
}

impl Size {
    /// Returns total data in kilobytes.
    #[must_use]
    pub const fn total_kb(&self) -> u64 {
        self.total_kb
    }

    /// Returns free data in kilobytes.
    #[must_use]
    pub const fn free_kb(&self) -> u64 {
        self.free_kb
    }

    /// Returns the used percentage.
    #[must_use]
    pub const fn used_percent(&self) -> u64 {
        let used_kb = self.total_kb - self.free_kb;
        let x = used_kb * 100;
        let y = self.total_kb;

        x / y
    }
}

/// A storage pool.
#[derive(Clone, Eq, PartialEq, Ord, PartialOrd, Hash, Debug, Default)]
pub struct Pool {
    name: String,
    data: Option<Size>,
    meta: Option<Size>,
}

impl Pool {
    /// Returns the pool name.
    #[must_use]
    pub fn name(&self) -> &str {
        &self.name
    }

    /// Returns the object data size.
    #[must_use]
    pub const fn data(&self) -> Option<&Size> {
        self.data.as_ref()
    }

    /// Returns the metadata size.
    #[must_use]
    pub const fn meta(&self) -> Option<&Size> {
        self.meta.as_ref()
    }
}

impl FromStr for Pool {
    type Err = anyhow::Error;

    fn from_str(s: &str) -> Result<Self> {
        let tokens = s
            .split(' ')
            .filter(|token| !token.is_empty())
            .collect::<Vec<_>>();

        let name = tokens[0].into();

        let data = if tokens[4] == "yes" {
            let total_kb = tokens[6].parse::<u64>().with_context(|| {
                format!("parsing data totalkb token {} to u64", tokens[6])
            })?;

            let free_kb = tokens[7].parse::<u64>().with_context(|| {
                format!("parsing data freekb token {} to u64", tokens[7])
            })?;

            Some(Size { total_kb, free_kb })
        } else {
            None
        };

        let meta = if tokens[5] == "yes" {
            let (total_kb_token_id, free_kb_token_id) =
                if tokens[8] == "(" { (10, 11) } else { (9, 10) };

            let total_kb = tokens[total_kb_token_id]
                .parse::<u64>()
                .with_context(|| {
                    format!(
                        "parsing meta totalkb token {} to u64",
                        tokens[total_kb_token_id]
                    )
                })?;

            let free_kb = tokens[free_kb_token_id]
                .parse::<u64>()
                .with_context(|| {
                    format!(
                        "parsing meta freekb token {} to u64",
                        tokens[free_kb_token_id]
                    )
                })?;

            Some(Size { total_kb, free_kb })
        } else {
            None
        };

        if data.is_none() && meta.is_none() {
            Err(anyhow!("pool {} contains neither data nor metadata", name))
        } else {
            Ok(Self { name, data, meta })
        }
    }
}

fn parse_mmlspool_output(s: &str) -> Result<Vec<Pool>> {
    let mut pools = Vec::with_capacity(16);

    for line in s.lines().skip(2) {
        let pool = line
            .parse()
            .with_context(|| format!("parsing pool line: {line}"))?;

        pools.push(pool);
    }

    Ok(pools)
}

impl crate::prom::ToText for Vec<Filesystem> {
    fn to_prom(&self, output: &mut impl Write) -> Result<()> {
        writeln!(
            output,
            "# HELP gpfs_fs_pool_total_kbytes GPFS pool size in kilobytes."
        )?;
        writeln!(output, "# TYPE gpfs_fs_pool_total_kbytes gauge")?;

        for fs in self {
            for pool in &fs.pools {
                if let Some(size) = &pool.data {
                    writeln!(
                    output,
                    "gpfs_fs_pool_total_kbytes{{fs=\"{}\",pool=\"{}\",type=\"data\"}} {}",
                    fs.name,
                    pool.name,
                    size.total_kb
                )?;
                }

                if let Some(size) = &pool.meta {
                    writeln!(
                    output,
                    "gpfs_fs_pool_total_kbytes{{fs=\"{}\",pool=\"{}\",type=\"meta\"}} {}",
                    fs.name,
                    pool.name,
                    size.total_kb
                )?;
                }
            }
        }

        writeln!(
            output,
            "# HELP gpfs_fs_pool_free_kbytes GPFS pool free kilobytes."
        )?;
        writeln!(output, "# TYPE gpfs_fs_pool_free_kbytes gauge")?;

        for fs in self {
            for pool in &fs.pools {
                if let Some(size) = &pool.data {
                    writeln!(
                    output,
                    "gpfs_fs_pool_free_kbytes{{fs=\"{}\",pool=\"{}\",type=\"data\"}} {}",
                    fs.name,
                    pool.name,
                    size.free_kb
                )?;
                }

                if let Some(size) = &pool.meta {
                    writeln!(
                    output,
                    "gpfs_fs_pool_free_kbytes{{fs=\"{}\",pool=\"{}\",type=\"meta\"}} {}",
                    fs.name,
                    pool.name,
                    size.free_kb
                )?;
                }
            }
        }

        Ok(())
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::prom::ToText;

    #[test]
    fn parse() {
        let input = include_str!("pool-example.in");

        let pools = parse_mmlspool_output(input).unwrap();
        assert_eq!(pools.len(), 4);

        assert_eq!(
            pools[0],
            Pool {
                name: "system".into(),
                data: None,
                meta: Some(Size {
                    total_kb: 25_004_867_584,
                    free_kb: 9_798_959_104,
                }),
            }
        );

        assert_eq!(
            pools[1],
            Pool {
                name: "nvme".into(),
                data: Some(Size {
                    total_kb: 162_531_639_296,
                    free_kb: 114_505_474_048,
                }),
                meta: None,
            }
        );

        assert_eq!(pools[1].data.unwrap().used_percent(), 29);

        assert_eq!(
            pools[2],
            Pool {
                name: "nlsas".into(),
                data: Some(Size {
                    total_kb: 1_997_953_957_888,
                    free_kb: 1_981_410_271_232,
                }),
                meta: None,
            }
        );

        assert_eq!(
            pools[3],
            Pool {
                name: "dangerzone".into(),
                data: Some(Size {
                    total_kb: 42,
                    free_kb: 42,
                }),
                meta: Some(Size {
                    total_kb: 42,
                    free_kb: 42,
                }),
            }
        );
    }

    #[test]
    fn prometheus() {
        let fs = Filesystem {
            name: "gpfs1".into(),
            pools: vec![
                Pool {
                    name: "system".into(),
                    data: None,
                    meta: Some(Size {
                        total_kb: 25_004_867_584,
                        free_kb: 9_798_959_104,
                    }),
                },
                Pool {
                    name: "nvme".into(),
                    data: Some(Size {
                        total_kb: 162_531_639_296,
                        free_kb: 114_505_474_048,
                    }),
                    meta: None,
                },
                Pool {
                    name: "nlsas".into(),
                    data: Some(Size {
                        total_kb: 1_997_953_957_888,
                        free_kb: 1_981_410_271_232,
                    }),
                    meta: None,
                },
            ],
        };

        let mut output = vec![];
        vec![fs].to_prom(&mut output).unwrap();

        let metrics = std::str::from_utf8(output.as_slice()).unwrap();

        let expected = include_str!("pool-example.prom");
        assert_eq!(metrics, expected);
    }
}