clean up

Signed-off-by: Xiaolong Fu <[email protected]>

.gitignore

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 # Exclude execute log
 /*.log
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+.vscode

docs/upgrade.md

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+# Upgrade Plan
+
+Our Goals:
+
+- Encapsulated processes and information packets.(Nov. 2024)
+- The external definition of connections.(Oct. 2024)
+- Asynchronous.(Nov. 2024)
+- Information packets with unique ownership and defined lifetimes.(Rust features)
+- Bounded connections with a finite capacity. (tokio)
+- Reserve pressure. (tokio)
+- Parser.(Nov. or Dec. 2024)
+
+
+
+## Encapsulated processes and information packets
+
+- [ ] Provide a new trait `Node` that defines unique identifiers for nodes, input channels for receiving packets, output channels for sending packets, and an interface to start the workload, replacing the trait `Task` in the old version. 
+- [ ] Enable asynchronous operations inside and between processes in trait `Action`.
+- [ ] Use `Content` as encapsulation of information packet.
+
+## The external definition of connections
+
+- [ ] Provide asynchronous channels encapsulating the tokio channels and provide a unified interface.
+
+## Asynchronous
+
+- [ ] Provide a struct `Graph`, replacing `Dag` in the old version.
+  - [ ] Remove field `rely_graph`.
+  - [ ] Automatically create channels and assign corresponding senders and receivers to the nodes when building the graph.
+  - [ ] Modify the logic of error-handling: If one node fails, the graph will not stop running, and users can then handle exceptions or errors at a successor node.
+
+## Bounded connections with a finite capacity 
+
+[tokio]: https://tokio.rs/tokio/tutorial	"tokio"
+
+ provides four different channel implementations. 
+
+-  `one-shot` is a channel with a single producer and a single consumer. Only one value can be sent at the same time. 
+
+- `mpsc` is a channel that supports multiple producers and a single consumer. It is different from one-shot in that it supports sending multiple messages. 
+
+- `broadcast` is a channel that supports multiple producers and multiple consumers. Multiple values can be sent. 
+
+- `watch` is a variant of broadcast. The receiver can only see whether the latest value has changed.
+
+We pick `mpsc` and `broadcast` as the channels used in Dagrs because they meet the requirements for connections in FBP: they are bounded, have finite capacity and support reserve pressure.
+
+## Reserve pressure
+
+`tokio` provides congestion handling mechanisms for both `mpsc`and `broadcast` to deal with insufficient channel capacity or the consumer is too slow. 
+
+- `mpsc` will block the sender when the capacity is full. 
+- `broadcast` will drop the oldest value, and the slow consumers will get an exception the next time it calls the receive function.
+
+## Parser
+
+- [ ] Support defining custom nodes via macros.
+- [ ] Modify the macro `dependencies!` to add dependencies to the already defined nodes (implemented with the `Node` trait) and return with a `Graph` ready to start.