Improves deserialization efficiency for agents.

api/formats/swimos_recon/src/recon_parser/async_parser/mod.rs

@@ -289,6 +289,7 @@ impl LocationTracker {
 /// it completes. Not that this is cannot be used as a stand-alone decoder as it has no concept of
 /// a separator between frames. It needs to be incorporated into another decoder that can determine
 /// where one record ends and another begins.
+#[derive(Debug)]
 pub struct RecognizerDecoder<R> {
     parser: IncrementalReconParser,
     recognizer: R,

server/swimos_agent/src/agent_model/mod.rs

@@ -204,17 +204,28 @@ pub trait AgentDescription {
 /// although it will not provided any lifecycle events for the agent or its lanes.
 pub trait AgentSpec: AgentDescription + Sized + Send {
     /// The type of handler to run when a command is received for a value lane.
-    type ValCommandHandler: HandlerAction<Self, Completion = ()> + Send + 'static;
+    type ValCommandHandler<'a>: HandlerAction<Self, Completion = ()> + Send + 'a
+    where
+        Self: 'a;
 
     /// The type of handler to run when a command is received for a map lane.
-    type MapCommandHandler: HandlerAction<Self, Completion = ()> + Send + 'static;
+    type MapCommandHandler<'a>: HandlerAction<Self, Completion = ()> + Send + 'a
+    where
+        Self: 'a;
 
     /// The type of handler to run when a request is received to sync with a lane.
     type OnSyncHandler: HandlerAction<Self, Completion = ()> + Send + 'static;
 
     /// The type of the handler to run when an HTTP request is received for a lane.
     type HttpRequestHandler: HandlerAction<Self, Completion = ()> + Send + 'static;
 
+    /// A store of persistent deserializers that may be used by [`AgentSpec::on_value_command`]
+    /// and [`AgentSpec::on_map_command`].
+    type Deserializers: Send + 'static;
+
+    /// Create th store of deserializers that can be reused any number of times.
+    fn initialize_deserializers(&self) -> Self::Deserializers;
+
     /// The names and flags of all items (lanes and stores) in the agent.
     fn item_specs() -> HashMap<&'static str, ItemSpec>;
 
@@ -223,9 +234,15 @@ pub trait AgentSpec: AgentDescription + Sized + Send {
     /// accept commands.
     ///
     /// # Arguments
+    /// * `deserializers` - The store of persistent deserializers for the agent.
     /// * `lane` - The name of the lane.
     /// * `body` - The content of the command.
-    fn on_value_command(&self, lane: &str, body: BytesMut) -> Option<Self::ValCommandHandler>;
+    fn on_value_command<'a>(
+        &self,
+        deserializers: &'a mut Self::Deserializers,
+        lane: &str,
+        body: BytesMut,
+    ) -> Option<Self::ValCommandHandler<'a>>;
 
     /// Create an initializer that will consume the state of a value-like item, as reported by the runtime.
     ///
@@ -247,13 +264,15 @@ pub trait AgentSpec: AgentDescription + Sized + Send {
     /// for a map lane. There will be no handler if the lane does not exist or does not
     /// accept commands.
     /// # Arguments
+    /// * `deserializers` - The store of persistent deserializers for the agent.
     /// * `lane` - The name of the lane.
     /// * `body` - The content of the command.
-    fn on_map_command(
+    fn on_map_command<'a>(
         &self,
+        deserializers: &'a mut Self::Deserializers,
         lane: &str,
         body: MapMessage<BytesMut, BytesMut>,
-    ) -> Option<Self::MapCommandHandler>;
+    ) -> Option<Self::MapCommandHandler<'a>>;
 
     /// Create a handler that will update the state of an agent when a request is made to
     /// sync with a lane. There will be no handler if the lane does not exist.
@@ -1217,6 +1236,7 @@ where
             let add_commander = |address: Address<Text>| cmd_ids.borrow_mut().get_request(&address);
             let add_link = (add_downlink, add_commander);
             let add_lane = NoDynLanes;
+            let mut deserializers = item_model.initialize_deserializers();
 
             // Calling run_handler is very verbose so is pulled out into this macro to make the code easier to read.
             macro_rules! exec_handler {
@@ -1399,7 +1419,8 @@ where
                     match request {
                         LaneRequest::Command(body) => {
                             trace!(name = %name, "Received a command for a value-like lane.");
-                            if let Some(handler) = item_model.on_value_command(name.as_str(), body)
+                            if let Some(handler) =
+                                item_model.on_value_command(&mut deserializers, name.as_str(), body)
                             {
                                 let result = run_handler(
                                     &mut ActionContext::new(
@@ -1453,7 +1474,9 @@ where
                     match request {
                         LaneRequest::Command(body) => {
                             trace!(name = %name, "Received a command for a map-like lane.");
-                            if let Some(handler) = item_model.on_map_command(name.as_str(), body) {
+                            if let Some(handler) =
+                                item_model.on_map_command(&mut deserializers, name.as_str(), body)
+                            {
                                 let result = run_handler(
                                     &mut ActionContext::new(
                                         &suspended,

server/swimos_agent/src/agent_model/tests/external_links/empty_agent.rs

@@ -37,19 +37,32 @@ impl AgentDescription for EmptyAgent {
 }
 
 impl AgentSpec for EmptyAgent {
-    type ValCommandHandler = UnitHandler;
+    type ValCommandHandler<'a> = UnitHandler
+    where
+        Self: 'a;
 
-    type MapCommandHandler = UnitHandler;
+    type MapCommandHandler<'a> = UnitHandler
+    where
+        Self: 'a;
 
     type OnSyncHandler = UnitHandler;
 
     type HttpRequestHandler = UnitHandler;
 
+    type Deserializers = ();
+
+    fn initialize_deserializers(&self) -> Self::Deserializers {}
+
     fn item_specs() -> HashMap<&'static str, ItemSpec> {
         HashMap::new()
     }
 
-    fn on_value_command(&self, _lane: &str, _body: BytesMut) -> Option<Self::ValCommandHandler> {
+    fn on_value_command(
+        &self,
+        _: &mut (),
+        _lane: &str,
+        _body: BytesMut,
+    ) -> Option<Self::ValCommandHandler<'_>> {
         None
     }
 
@@ -67,11 +80,12 @@ impl AgentSpec for EmptyAgent {
         None
     }
 
-    fn on_map_command(
+    fn on_map_command<'a>(
         &self,
+        _: &'a mut (),
         _lane: &str,
         _body: MapMessage<BytesMut, BytesMut>,
-    ) -> Option<Self::MapCommandHandler> {
+    ) -> Option<Self::MapCommandHandler<'a>> {
         None
     }
 

server/swimos_agent/src/agent_model/tests/fake_agent.rs

@@ -168,9 +168,13 @@ impl AgentDescription for TestAgent {
 }
 
 impl AgentSpec for TestAgent {
-    type ValCommandHandler = TestHandler;
+    type ValCommandHandler<'a> = TestHandler
+    where
+        Self: 'a;
 
-    type MapCommandHandler = TestHandler;
+    type MapCommandHandler<'a> = TestHandler
+    where
+        Self: 'a;
 
     type OnSyncHandler = TestHandler;
 
@@ -219,7 +223,12 @@ impl AgentSpec for TestAgent {
         lanes
     }
 
-    fn on_value_command(&self, lane: &str, body: BytesMut) -> Option<Self::ValCommandHandler> {
+    fn on_value_command<'a>(
+        &self,
+        _: &'a mut (),
+        lane: &str,
+        body: BytesMut,
+    ) -> Option<Self::ValCommandHandler<'a>> {
         match lane {
             VAL_LANE => Some(
                 TestEvent::Value {
@@ -264,11 +273,12 @@ impl AgentSpec for TestAgent {
         None
     }
 
-    fn on_map_command(
+    fn on_map_command<'a>(
         &self,
+        _: &'a mut (),
         lane: &str,
         body: MapMessage<BytesMut, BytesMut>,
-    ) -> Option<Self::MapCommandHandler> {
+    ) -> Option<Self::MapCommandHandler<'a>> {
         match lane {
             MAP_LANE => Some(
                 TestEvent::Map {
@@ -426,6 +436,10 @@ impl AgentSpec for TestAgent {
             Err(DynamicRegistrationError::DuplicateName(name.to_string()))
         }
     }
+
+    type Deserializers = ();
+
+    fn initialize_deserializers(&self) -> Self::Deserializers {}
 }
 
 impl HandlerAction<TestAgent> for TestHandler {

server/swimos_agent/src/event_handler/mod.rs

@@ -33,7 +33,7 @@ use swimos_api::{
 };
 use swimos_form::{read::RecognizerReadable, write::StructuralWritable};
 use swimos_model::Text;
-use swimos_recon::parser::{AsyncParseError, RecognizerDecoder};
+use swimos_recon::parser::AsyncParseError;
 use swimos_utilities::{never::Never, routing::RouteUri};
 use thiserror::Error;
 use tokio::time::Instant;
@@ -45,6 +45,7 @@ use crate::{
     },
     lanes::JoinLaneKind,
     meta::AgentMetadata,
+    ReconDecoder,
 };
 
 use bitflags::bitflags;
@@ -1283,23 +1284,21 @@ impl<Context, S: AsRef<str>> HandlerAction<Context> for GetParameter<S> {
 
 /// An event handler that will attempt to decode a [readable](`swimos_form::read::StructuralReadable`) type
 /// from a buffer, immediately returning the result or an error.
-pub struct Decode<T> {
-    _target_type: PhantomData<fn() -> T>,
+pub struct Decode<'a, T: RecognizerReadable> {
+    decoder: Option<&'a mut ReconDecoder<T>>,
     buffer: BytesMut,
-    complete: bool,
 }
 
-impl<T> Decode<T> {
-    pub fn new(buffer: BytesMut) -> Self {
+impl<'a, T: RecognizerReadable> Decode<'a, T> {
+    pub fn new(decoder: &'a mut ReconDecoder<T>, buffer: BytesMut) -> Self {
         Decode {
-            _target_type: PhantomData,
+            decoder: Some(decoder),
             buffer,
-            complete: false,
         }
     }
 }
 
-impl<Context, T: RecognizerReadable> HandlerAction<Context> for Decode<T> {
+impl<'a, T: RecognizerReadable, Context> HandlerAction<Context> for Decode<'a, T> {
     type Completion = T;
 
     fn step(
@@ -1308,27 +1307,24 @@ impl<Context, T: RecognizerReadable> HandlerAction<Context> for Decode<T> {
         _meta: AgentMetadata,
         _context: &Context,
     ) -> StepResult<Self::Completion> {
-        let Decode {
-            buffer, complete, ..
-        } = self;
-        if *complete {
-            StepResult::after_done()
-        } else {
-            let mut decoder = RecognizerDecoder::new(T::make_recognizer());
-            *complete = true;
+        let Decode { decoder, buffer } = self;
+        if let Some(decoder) = decoder.take() {
+            decoder.reset();
             match decoder.decode_eof(buffer) {
                 Ok(Some(value)) => StepResult::done(value),
                 Ok(_) => StepResult::Fail(EventHandlerError::IncompleteCommand),
                 Err(e) => StepResult::Fail(EventHandlerError::BadCommand(e)),
             }
+        } else {
+            StepResult::after_done()
         }
     }
 
     fn describe(&self, _context: &Context, f: &mut Formatter<'_>) -> Result<(), std::fmt::Error> {
         let Decode {
-            buffer, complete, ..
+            buffer, decoder, ..
         } = self;
-        let content = if *complete {
+        let content = if decoder.is_none() {
             CONSUMED
         } else {
             std::str::from_utf8(buffer.as_ref()).unwrap_or("<<BAD UTF8>>")

server/swimos_agent/src/event_handler/tests.rs

@@ -23,9 +23,10 @@ use tokio::time::Instant;
 
 use crate::agent_model::AgentDescription;
 use crate::event_handler::check_step::{check_is_complete, check_is_continue};
-use crate::event_handler::{GetParameter, ModificationFlags, WithParameters};
+use crate::event_handler::{Decode, GetParameter, ModificationFlags, WithParameters};
 
 use crate::test_context::{NO_DOWNLINKS, NO_DYN_LANES};
+use crate::ReconDecoder;
 use crate::{
     event_handler::{
         ConstHandler, EventHandlerError, GetAgentUri, HandlerActionExt, Sequentially, SideEffects,
@@ -36,7 +37,7 @@ use crate::{
 };
 
 use super::{
-    join, ActionContext, Decode, HandlerAction, HandlerFuture, Modification, ScheduleTimerEvent,
+    join, ActionContext, HandlerAction, HandlerFuture, Modification, ScheduleTimerEvent,
     SideEffect, Spawner, StepResult,
 };
 
@@ -526,14 +527,15 @@ fn followed_by_handler() {
 
 #[test]
 fn decoding_handler_success() {
+    let mut decoder = ReconDecoder::<i32>::default();
     let uri = make_uri();
     let route_params = HashMap::new();
     let meta = make_meta(&uri, &route_params);
 
     let mut buffer = BytesMut::new();
     write!(buffer, "56").expect("Write failed.");
 
-    let mut handler = Decode::<i32>::new(buffer);
+    let mut handler = Decode::<i32>::new(&mut decoder, buffer);
 
     let result = handler.step(
         &mut dummy_context(&mut HashMap::new(), &mut BytesMut::new()),
@@ -561,14 +563,15 @@ fn decoding_handler_success() {
 
 #[test]
 fn decoding_handler_failure() {
+    let mut decoder = ReconDecoder::<i32>::default();
     let uri = make_uri();
     let route_params = HashMap::new();
     let meta = make_meta(&uri, &route_params);
 
     let mut buffer = BytesMut::new();
     write!(buffer, "boom").expect("Write failed.");
 
-    let mut handler = Decode::<i32>::new(buffer);
+    let mut handler = Decode::<i32>::new(&mut decoder, buffer);
 
     let result = handler.step(
         &mut dummy_context(&mut HashMap::new(), &mut BytesMut::new()),

server/swimos_agent/src/lanes/command/mod.rs

@@ -31,6 +31,7 @@ use crate::{
     },
     item::AgentItem,
     meta::AgentMetadata,
+    ReconDecoder,
 };
 
 use super::{LaneItem, ProjTransform};
@@ -157,15 +158,16 @@ impl<C, T> HandlerTrans<T> for ProjTransform<C, CommandLane<T>> {
     }
 }
 
-pub type DecodeAndCommand<C, T> =
-    AndThen<Decode<T>, DoCommand<C, T>, ProjTransform<C, CommandLane<T>>>;
+pub type DecodeAndCommand<'a, C, T> =
+    AndThen<Decode<'a, T>, DoCommand<C, T>, ProjTransform<C, CommandLane<T>>>;
 
 /// Create an event handler that will decode an incoming command and apply it to a command lane.
 pub fn decode_and_command<C: AgentDescription, T: RecognizerReadable>(
+    decoder: &mut ReconDecoder<T>,
     buffer: BytesMut,
     projection: fn(&C) -> &CommandLane<T>,
 ) -> DecodeAndCommand<C, T> {
-    let decode: Decode<T> = Decode::new(buffer);
+    let decode: Decode<T> = Decode::new(decoder, buffer);
     decode.and_then(ProjTransform::new(projection))
 }