Struct Log 

pub struct Log { /* private fields */ }

Caller-owned heap history with fixed limits and monotonic append watermarks.

Implementations

impl Log

pub const fn new(limits: Limits) -> Self

Construct an empty log without preallocating the configured maximum.

Examples found in repository

examples/worker.rs (lines 7-11)

fn main() {
    let mut log = Log::new(Limits {
        max_entries: NonZeroUsize::new(8).expect("positive capacity"),
        max_message_bytes: 32,
        max_label_bytes: 16,
    });
    for (created_at_secs, level, message) in [
        (10, Level::Info, "delivery accepted"),
        (
            11,
            Level::Warn,
            "provider reply is still unknown; reconcile before retry",
        ),
        (12, Level::Ok, "original delivery reconciled"),
    ] {
        log.append(EntryInput {
            created_at_secs,
            level,
            source: "worker",
            topic: Some("delivery"),
            message,
        })
        .expect("valid bounded entry");
    }
    let page = log.page(
        Filter::default(),
        PageRequest {
            before: None,
            max_results: NonZeroUsize::new(8).expect("positive results"),
            max_scanned: NonZeroUsize::new(8).expect("positive scan"),
        },
    );
    for entry in page.entries {
        println!("{} {:?}: {}", entry.sequence, entry.level, entry.message);
    }
    let batch = log.prune_expired(16, 5, 1);
    assert_eq!(batch.removed, 1);
    assert_eq!(log.next_expiry_secs(5), Some(17));
}

pub fn len(&self) -> usize

Return the retained row count.

pub fn is_empty(&self) -> bool

Whether this log currently has no retained rows.

pub fn append(&mut self, input: EntryInput<'_>) -> Result<u64, AppendError>

Admit one row and evict the oldest if the count ceiling is reached.

Errors

Returns a typed refusal for oversized labels, regressed time or exhausted sequence identities. Validation completes before any eviction or mutation.

Examples found in repository

examples/worker.rs (lines 21-27)

fn main() {
    let mut log = Log::new(Limits {
        max_entries: NonZeroUsize::new(8).expect("positive capacity"),
        max_message_bytes: 32,
        max_label_bytes: 16,
    });
    for (created_at_secs, level, message) in [
        (10, Level::Info, "delivery accepted"),
        (
            11,
            Level::Warn,
            "provider reply is still unknown; reconcile before retry",
        ),
        (12, Level::Ok, "original delivery reconciled"),
    ] {
        log.append(EntryInput {
            created_at_secs,
            level,
            source: "worker",
            topic: Some("delivery"),
            message,
        })
        .expect("valid bounded entry");
    }
    let page = log.page(
        Filter::default(),
        PageRequest {
            before: None,
            max_results: NonZeroUsize::new(8).expect("positive results"),
            max_scanned: NonZeroUsize::new(8).expect("positive scan"),
        },
    );
    for entry in page.entries {
        println!("{} {:?}: {}", entry.sequence, entry.level, entry.message);
    }
    let batch = log.prune_expired(16, 5, 1);
    assert_eq!(batch.removed, 1);
    assert_eq!(log.next_expiry_secs(5), Some(17));
}

pub fn prune_expired( &mut self, now_secs: u64, max_age_secs: u64, max_remove: usize, ) -> RetentionBatch

Remove at most max_remove entries strictly older than the age cutoff. An entry remains available through its full configured age second.

Examples found in repository

examples/worker.rs (line 41)

fn main() {
    let mut log = Log::new(Limits {
        max_entries: NonZeroUsize::new(8).expect("positive capacity"),
        max_message_bytes: 32,
        max_label_bytes: 16,
    });
    for (created_at_secs, level, message) in [
        (10, Level::Info, "delivery accepted"),
        (
            11,
            Level::Warn,
            "provider reply is still unknown; reconcile before retry",
        ),
        (12, Level::Ok, "original delivery reconciled"),
    ] {
        log.append(EntryInput {
            created_at_secs,
            level,
            source: "worker",
            topic: Some("delivery"),
            message,
        })
        .expect("valid bounded entry");
    }
    let page = log.page(
        Filter::default(),
        PageRequest {
            before: None,
            max_results: NonZeroUsize::new(8).expect("positive results"),
            max_scanned: NonZeroUsize::new(8).expect("positive scan"),
        },
    );
    for entry in page.entries {
        println!("{} {:?}: {}", entry.sequence, entry.level, entry.message);
    }
    let batch = log.prune_expired(16, 5, 1);
    assert_eq!(batch.removed, 1);
    assert_eq!(log.next_expiry_secs(5), Some(17));
}

pub fn next_expiry_secs(&self, max_age_secs: u64) -> Option<u64>

First second at which the oldest row expires; None for empty history or overflow.

Examples found in repository

examples/worker.rs (line 43)

fn main() {
    let mut log = Log::new(Limits {
        max_entries: NonZeroUsize::new(8).expect("positive capacity"),
        max_message_bytes: 32,
        max_label_bytes: 16,
    });
    for (created_at_secs, level, message) in [
        (10, Level::Info, "delivery accepted"),
        (
            11,
            Level::Warn,
            "provider reply is still unknown; reconcile before retry",
        ),
        (12, Level::Ok, "original delivery reconciled"),
    ] {
        log.append(EntryInput {
            created_at_secs,
            level,
            source: "worker",
            topic: Some("delivery"),
            message,
        })
        .expect("valid bounded entry");
    }
    let page = log.page(
        Filter::default(),
        PageRequest {
            before: None,
            max_results: NonZeroUsize::new(8).expect("positive results"),
            max_scanned: NonZeroUsize::new(8).expect("positive scan"),
        },
    );
    for entry in page.entries {
        println!("{} {:?}: {}", entry.sequence, entry.level, entry.message);
    }
    let batch = log.prune_expired(16, 5, 1);
    assert_eq!(batch.removed, 1);
    assert_eq!(log.next_expiry_secs(5), Some(17));
}

pub fn page(&self, filter: Filter<'_>, request: PageRequest) -> Page<'_>

Scan newest-first without cloning retained messages or counting every match. Follow next_before with the same filters, including after an empty page.

Examples found in repository

examples/worker.rs (lines 30-37)

fn main() {
    let mut log = Log::new(Limits {
        max_entries: NonZeroUsize::new(8).expect("positive capacity"),
        max_message_bytes: 32,
        max_label_bytes: 16,
    });
    for (created_at_secs, level, message) in [
        (10, Level::Info, "delivery accepted"),
        (
            11,
            Level::Warn,
            "provider reply is still unknown; reconcile before retry",
        ),
        (12, Level::Ok, "original delivery reconciled"),
    ] {
        log.append(EntryInput {
            created_at_secs,
            level,
            source: "worker",
            topic: Some("delivery"),
            message,
        })
        .expect("valid bounded entry");
    }
    let page = log.page(
        Filter::default(),
        PageRequest {
            before: None,
            max_results: NonZeroUsize::new(8).expect("positive results"),
            max_scanned: NonZeroUsize::new(8).expect("positive scan"),
        },
    );
    for entry in page.entries {
        println!("{} {:?}: {}", entry.sequence, entry.level, entry.message);
    }
    let batch = log.prune_expired(16, 5, 1);
    assert_eq!(batch.removed, 1);
    assert_eq!(log.next_expiry_secs(5), Some(17));
}

Trait Implementations

impl Debug for Log

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.