Add ABCI domain types.

These types mirror the generated types in tendermint_proto, but have better
naming.  The documentation is filled in from the ABCI methods & types
documentation.

tendermint/src/abci.rs

@@ -1,18 +1,58 @@
-//! Application BlockChain Interface (ABCI)
+//! Application BlockChain Interface ([ABCI]) is the interface between Tendermint
+//! (a consensus engine for Byzantine-fault-tolerant replication of a state
+//! machine) and an application (the state machine to be replicated).
 //!
-//! NOTE: This module contains types for ABCI responses as consumed from RPC
-//! endpoints. It does not contain an ABCI protocol implementation.
+//! Using ABCI involves writing an application driven by ABCI methods, exposing
+//! that application as an ABCI server, and having Tendermint connect to the
+//! server as an ABCI client.
 //!
-//! For that, see:
+//! This module does not include an ABCI server implementation itself. Instead,
+//! it provides a common set of Rust domain types that model the ABCI protocol,
+//! which can be used by both ABCI applications and ABCI server implementations.
 //!
-//! <https://github.com/tendermint/rust-abci>
+//! One ABCI server implementation is provided by the [`tendermint_abci`][tmabci]
+//! crate.
+//!
+//! Each ABCI method corresponds to a request/response pair. ABCI requests are
+//! modeled by the [`Request`] enum, and responses are modeled by the
+//! [`Response`] enum.  As described in the [methods and types][mat] page, ABCI
+//! methods are split into four categories. Tendermint opens one ABCI connection
+//! for each category of messages. These categories are modeled by the
+//! [`MethodKind`] enum and by per-category request and response enums:
+//!
+//! * [`ConsensusRequest`] /  [`ConsensusResponse`] for [`MethodKind::Consensus`] methods;
+//! * [`MempoolRequest`] /  [`MempoolResponse`] for [`MethodKind::Mempool`] methods;
+//! * [`InfoRequest`] /  [`InfoResponse`] for [`MethodKind::Info`] methods;
+//! * [`SnapshotRequest`] /  [`SnapshotResponse`] for [`MethodKind::Snapshot`] methods.
+//!
+//! The domain types in this module have conversions to and from the Protobuf
+//! types defined in the [`tendermint_proto`] crate. These conversions are
+//! required for ABCI server implementations, which use the protobufs to
+//! communicate with Tendermint, but should not be required for ABCI
+//! applications, which should use the domain types in an interface defined by
+//! their choice of ABCI server implementation.
+//!
+//! [ABCI]: https://docs.tendermint.com/master/spec/abci/
+//! [mat]: https://docs.tendermint.com/master/spec/abci/abci.html
+//! [tmabci]: https://github.com/informalsystems/tendermint-rs/tree/master/abci
 
 mod code;
 mod data;
 mod gas;
 mod info;
+mod kind;
 mod log;
 mod path;
+
+/// Events. Hide this later once types are merged.
+pub mod event;
+//pub use event::{Event, EventAttribute};
+
+pub mod params;
+pub mod request;
+pub mod response;
+pub mod types;
+
 pub mod responses;
 pub mod tag;
 pub mod transaction;
@@ -27,3 +67,10 @@ pub use self::{
     responses::{DeliverTx, Event, Responses},
     transaction::Transaction,
 };
+
+#[doc(inline)]
+pub use self::{
+    kind::MethodKind,
+    request::{ConsensusRequest, InfoRequest, MempoolRequest, Request, SnapshotRequest},
+    response::{ConsensusResponse, InfoResponse, MempoolResponse, Response, SnapshotResponse},
+};

tendermint/src/abci/event.rs

@@ -0,0 +1,182 @@
+/// An event that occurred while processing a request.
+///
+/// Application developers can attach additional information to
+/// [`BeginBlock`](super::response::BeginBlock),
+/// [`EndBlock`](super::response::EndBlock),
+/// [`CheckTx`](super::response::CheckTx), and
+/// [`DeliverTx`](super::response::DeliverTx) responses. Later, transactions may
+/// be queried using these events.
+///
+/// [ABCI documentation](https://docs.tendermint.com/master/spec/abci/abci.html#events)
+#[derive(Clone, PartialEq, Eq, Debug)]
+pub struct Event {
+    /// The kind of event.
+    ///
+    /// Tendermint calls this the `type`, but we use `kind` to avoid confusion
+    /// with Rust types and follow Rust conventions.
+    pub kind: String,
+    /// A list of [`EventAttribute`]s describing the event.
+    pub attributes: Vec<EventAttribute>,
+}
+
+impl Event {
+    /// Construct an event from generic data.
+    ///
+    /// The `From` impls on [`EventAttribute`] and the [`EventAttributeIndexExt`]
+    /// trait allow ergonomic event construction, as in this example:
+    ///
+    /// ```
+    /// use tendermint::abci::event::{Event, EventAttributeIndexExt};
+    ///
+    /// let event = Event::new(
+    ///     "app",
+    ///     vec![
+    ///         ("key1", "value1").index(),
+    ///         ("key2", "value2").index(),
+    ///         ("key3", "value3").no_index(), // will not be indexed
+    ///     ],
+    /// );
+    /// ```
+    // XXX(hdevalence): remove vec! from example after https://github.com/rust-lang/rust/pull/65819
+    pub fn new<K, I>(kind: K, attributes: I) -> Self
+    where
+        K: Into<String>,
+        I: IntoIterator,
+        I::Item: Into<EventAttribute>,
+    {
+        Self {
+            kind: kind.into(),
+            attributes: attributes.into_iter().map(Into::into).collect(),
+        }
+    }
+}
+
+/// A key-value pair describing an [`Event`].
+///
+/// Generic methods are provided for more ergonomic attribute construction, see
+/// [`Event::new`] for details.
+///
+/// [ABCI documentation](https://docs.tendermint.com/master/spec/abci/abci.html#events)
+#[derive(Clone, PartialEq, Eq, Debug)]
+pub struct EventAttribute {
+    /// The event key.
+    pub key: String,
+    /// The event value.
+    pub value: String,
+    /// Whether Tendermint's indexer should index this event.
+    ///
+    /// **This field is nondeterministic**.
+    pub index: bool,
+}
+
+impl<K: Into<String>, V: Into<String>> From<(K, V, bool)> for EventAttribute {
+    fn from((key, value, index): (K, V, bool)) -> Self {
+        EventAttribute {
+            key: key.into(),
+            value: value.into(),
+            index,
+        }
+    }
+}
+
+/// Adds convenience methods to tuples for more ergonomic [`EventAttribute`]
+/// construction.
+///
+/// See [`Event::new`] for details.
+#[allow(missing_docs)]
+pub trait EventAttributeIndexExt: private::Sealed {
+    type Key;
+    type Value;
+
+    /// Indicate that this key/value pair should be indexed by Tendermint.
+    fn index(self) -> (Self::Key, Self::Value, bool);
+    /// Indicate that this key/value pair should not be indexed by Tendermint.
+    fn no_index(self) -> (Self::Key, Self::Value, bool);
+}
+
+impl<K: Into<String>, V: Into<String>> EventAttributeIndexExt for (K, V) {
+    type Key = K;
+    type Value = V;
+    fn index(self) -> (K, V, bool) {
+        let (key, value) = self;
+        (key, value, true)
+    }
+    fn no_index(self) -> (K, V, bool) {
+        let (key, value) = self;
+        (key, value, false)
+    }
+}
+
+mod private {
+    pub trait Sealed {}
+
+    impl<K: Into<String>, V: Into<String>> Sealed for (K, V) {}
+}
+
+impl<K: Into<String>, V: Into<String>> From<(K, V)> for EventAttribute {
+    fn from((key, value): (K, V)) -> Self {
+        (key, value, false).into()
+    }
+}
+
+// =============================================================================
+// Protobuf conversions
+// =============================================================================
+
+// XXX(hdevalence): these all use &'static str for now, this should be fixed
+// to align with the crate's error-handling strategy.
+
+use std::convert::{TryFrom, TryInto};
+
+use tendermint_proto::abci as pb;
+use tendermint_proto::Protobuf;
+
+impl From<EventAttribute> for pb::EventAttribute {
+    fn from(event: EventAttribute) -> Self {
+        Self {
+            key: event.key,
+            value: event.value,
+            index: event.index,
+        }
+    }
+}
+
+impl TryFrom<pb::EventAttribute> for EventAttribute {
+    type Error = crate::Error;
+
+    fn try_from(event: pb::EventAttribute) -> Result<Self, Self::Error> {
+        Ok(Self {
+            key: event.key,
+            value: event.value,
+            index: event.index,
+        })
+    }
+}
+
+impl Protobuf<pb::EventAttribute> for EventAttribute {}
+
+impl From<Event> for pb::Event {
+    fn from(event: Event) -> Self {
+        Self {
+            r#type: event.kind,
+            attributes: event.attributes.into_iter().map(Into::into).collect(),
+        }
+    }
+}
+
+impl TryFrom<pb::Event> for Event {
+    type Error = crate::Error;
+
+    fn try_from(event: pb::Event) -> Result<Self, Self::Error> {
+        Ok(Self {
+            kind: event.r#type,
+            attributes: event
+                .attributes
+                .into_iter()
+                .map(TryInto::try_into)
+                .collect::<Result<_, _>>()?,
+        })
+    }
+}
+
+impl Protobuf<pb::Event> for Event {}

tendermint/src/abci/kind.rs

@@ -0,0 +1,23 @@
+/// A category of ABCI method.
+///
+/// ABCI methods are split into four categories. Tendermint opens one ABCI
+/// connection for each category and refers to these categories as *connections*,
+/// but nothing actually restricts an ABCI connection from calling methods in
+/// multiple categories.
+///
+/// This enum breaks out the `Flush` method as a distinct category, since it is
+/// used to control the execution of other methods.
+pub enum MethodKind {
+    /// A consensus method, driven by the consensus protocol and responsible for
+    /// block execution.
+    Consensus,
+    /// A mempool method, used for validating new transactions before they're
+    /// shared or included in a block.
+    Mempool,
+    /// A snapshot method, used for serving and restoring state snapshots.
+    Snapshot,
+    /// An info method, used for initialization and user queries.
+    Info,
+    /// The flush method requests that all pending method requests are fully executed.
+    Flush,
+}