dial9_trace_format/
lib.rs

1//! # dial9-trace-format
2//!
3//! A compact binary trace format for recording timestamped events with
4//! schema-driven encoding. Events are described by schemas (registered at
5//! write time) and encoded with delta-compressed timestamps, LEB128 varints,
6//! and an interned string pool.
7//!
8//! ## Crate layout
9//!
10//! - [`encoder`] — high-level [`Encoder`](encoder::Encoder) for writing traces
11//! - [`decoder`] — streaming [`Decoder`](decoder::Decoder) for reading traces
12//! - [`codec`]   — wire-format types ([`WireTypeId`](codec::WireTypeId),
13//!   [`PoolEntry`](codec::PoolEntry)) that appear in decoded frames
14//! - [`schema`]  — [`SchemaEntry`] and
15//!   [`FieldDef`] describing event layouts
16//! - [`types`]   — field value types, the [`TraceField`]
17//!   trait, and the [`EventEncoder`] used by derived code
18
19pub mod codec;
20pub mod decoder;
21pub mod encoder;
22pub(crate) mod leb128;
23pub mod schema;
24pub mod types;
25
26pub use dial9_trace_format_derive::TraceEvent;
27pub use types::EventEncoder;
28pub use types::FieldValue;
29pub use types::InternedString;
30pub use types::StackFrames;
31pub use types::TraceField;
32
33use schema::{FieldDef, SchemaEntry};
34use types::FieldValueRef;
35
36/// Trait implemented by `#[derive(TraceEvent)]` for compile-time event types.
37pub trait TraceEvent {
38    /// Decoded form of this event, potentially borrowing from the input buffer.
39    type Ref<'a>;
40
41    /// The event type name (used in schema registration).
42    fn event_name() -> &'static str;
43    /// Field definitions for schema registration.
44    /// When `has_timestamp()` is true, the timestamp is NOT included here —
45    /// it is encoded in the event frame header.
46    fn field_defs() -> Vec<FieldDef>;
47    /// Whether this event type carries a packed timestamp in the event header.
48    fn has_timestamp() -> bool {
49        true
50    }
51    /// Return the event's timestamp in nanoseconds.
52    fn timestamp(&self) -> u64;
53    /// Encode this event's non-timestamp fields into the encoder.
54    fn encode_fields<W: std::io::Write>(
55        &self,
56        enc: &mut types::EventEncoder<'_, W>,
57    ) -> std::io::Result<()>;
58    /// Decode from field values using field definitions for name resolution.
59    /// `timestamp_ns` is the absolute timestamp from the event header (if present).
60    fn decode<'a>(
61        timestamp_ns: Option<u64>,
62        fields: &[FieldValueRef<'a>],
63        field_defs: &[FieldDef],
64    ) -> Option<Self::Ref<'a>>;
65
66    /// Build a SchemaEntry for this event type.
67    fn schema_entry() -> SchemaEntry {
68        SchemaEntry {
69            name: Self::event_name().to_string(),
70            has_timestamp: Self::has_timestamp(),
71            fields: Self::field_defs(),
72        }
73    }
74}
dial9_trace_format/lib.rs

dial9_trace_format/
lib.rs
