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cognis-graph (crate name cognis-graph, repo dir crates/cognisgraph) is the graph runtime. Pregel-style supersteps, typed state, conditional Goto, three checkpointer backends, seven stream modes, three viz formats.Field Value Latest version 0.3docs.rs docs.rs/cognis-graph Repo path crates/cognisgraphDefault features none
Modules at a glance Module What builderGraph<S>, LinearBuilder.compiledCompiledGraph<S> — implements Runnable<S, S>, plus checkpoint/interrupt/resume methods.nodeNode, NodeCtx, NodeOut, node_fn.gotoGoto enum + constructors.stateGraphState trait.checkpointCheckpointer trait + InMemoryCheckpointer, SqliteCheckpointer, PostgresCheckpointer.engineInternal Pregel runner. Not for direct use. stream_modeStreamMode, StreamModes.vizto_dot, to_mermaid, to_ascii (methods on CompiledGraph).subgraphSubgraph for nested graphs.metrics, audit_logObservability helpers. retryNodeRetryPolicy for per-node retry.
Key types Graph<S>pub struct Graph < S : GraphState > { /* … */ } impl < S : GraphState > Graph < S > { pub fn new () -> Self ; pub fn with_version ( self , v : impl Into < String >) -> Self ; pub fn node ( self , name : impl Into < String >, node : impl Node < S > + ' static ) -> Self ; pub fn edge ( self , from : impl Into < String >, to : impl Into < String >) -> Self ; pub fn start_at ( self , name : impl Into < String >) -> Self ; pub fn compile ( self ) -> Result < CompiledGraph < S >>; } impl Graph <()> { pub fn linear () -> LinearBuilder ; }
node_fn pub fn node_fn < S , F , Fut >( name : impl Into < String >, f : F ) -> impl Node < S > where S : GraphState , F : Fn ( & S , & NodeCtx ) -> Fut + Send + Sync + ' static , Fut : Future < Output = Result < NodeOut < S >>> + Send + ' static ;
NodeOut pub struct NodeOut < S : GraphState > { pub update : S :: Update , pub goto : Goto , } impl < S > NodeOut < S > { pub fn end_with ( update : S :: Update ) -> Self ; pub fn goto_only ( goto : Goto ) -> Self ; }
Goto pub enum Goto { Node ( String ), Multiple ( Vec < String >), Send ( Vec <( String , serde_json :: Value )>), Halt , End , } impl Goto { pub fn node ( name : impl Into < String >) -> Self ; pub fn end () -> Self ; pub fn halt () -> Self ; pub fn targets ( & self ) -> Vec < & str >; pub fn is_end ( & self ) -> bool ; }
GraphState pub trait GraphState : Send + Sync { type Update : Default + Send + Sync ; fn apply ( & mut self , update : Self :: Update ); }
#[derive(GraphStateV2)] from cognis-macros emits the Update struct and the impl. Reducer attributes: #[reducer(append/last_value/add/merge)].CompiledGraph<S>impl < S : GraphState + Clone + Send + ' static > CompiledGraph < S > { pub fn with_checkpointer ( self , cp : Arc < dyn Checkpointer < S >>) -> Self ; pub fn with_interrupt_before < I , N >( self , names : I ) -> Self ; pub fn with_interrupt_after < I , N >( self , names : I ) -> Self ; pub async fn invoke ( & self , input : S , config : RunnableConfig ) -> Result < S >; pub async fn resume ( & self , run_id : Uuid , step : u64 , state : S , config : RunnableConfig ) -> Result < S >; pub async fn get_state ( & self , run_id : Uuid ) -> Result < Option < S >>; pub async fn get_state_at ( & self , run_id : Uuid , step : u64 ) -> Result < Option < S >>; pub async fn get_state_history ( & self , run_id : Uuid ) -> Result < Vec <( u64 , S )>>; pub async fn update_state ( & self , run_id : Uuid , step : u64 , state : & S ) -> Result <()>; pub async fn stream_mode ( & self , input : S , modes : StreamModes , config : RunnableConfig ) -> Result < EventStream >; pub fn to_dot ( & self ) -> String ; pub fn to_mermaid ( & self ) -> String ; pub fn to_ascii ( & self ) -> String ; }
Checkpointer pub trait Checkpointer < S : GraphState > : Send + Sync { async fn save ( & self , run_id : Uuid , step : u64 , state : & S ) -> Result <()>; async fn load ( & self , run_id : Uuid , step : Option < u64 >) -> Result < Option < S >>; async fn list ( & self , run_id : Uuid ) -> Result < Vec < u64 >>; async fn delete ( & self , run_id : Uuid ) -> Result <()>; }
Implementations: InMemoryCheckpointer<S>::new(), SqliteCheckpointer::open(path) (feature sqlite), PostgresCheckpointer::connect(dsn) (feature postgres).
StreamMode pub enum StreamMode { Values , Updates , Messages , Tasks , Checkpoints , Debug , Custom , }
StreamModes::only(StreamMode::Updates), StreamModes::default().push(...), StreamModes::debug(), StreamModes::none().Feature flags Feature Pulls in sqlitesqlx/sqlite for SqliteCheckpointer.postgressqlx/postgres for PostgresCheckpointer.serializer-cborCBOR-encoded checkpoint payloads.
See also
Graphs and state User guide.
Control flow Goto, edges, fan-out.
Checkpointing Time travel and resume.
Streaming Per-mode event streams.