protoflow_blocks/blocks/sys/
read_file.rs

1// This is free and unencumbered software released into the public domain.
2
3extern crate std;
4
5use crate::{
6    prelude::{vec, Bytes, String, Vec},
7    StdioConfig, StdioError, StdioSystem, System,
8};
9use protoflow_core::{Block, BlockResult, BlockRuntime, InputPort, OutputPort};
10use protoflow_derive::Block;
11use simple_mermaid::mermaid;
12
13/// A block that reads bytes from the contents of a file.
14///
15/// # Block Diagram
16#[doc = mermaid!("../../../doc/sys/read_file.mmd")]
17///
18/// # Sequence Diagram
19#[doc = mermaid!("../../../doc/sys/read_file.seq.mmd" framed)]
20///
21/// # Examples
22///
23/// ## Using the block in a system
24///
25/// ```rust
26/// # use protoflow_blocks::*;
27/// # fn main() {
28/// System::build(|s| {
29///     // TODO
30/// });
31/// # }
32/// ```
33///
34/// ## Running the block via the CLI
35///
36/// ```console
37/// $ protoflow execute ReadFile path=/tmp/file.txt
38/// ```
39///
40#[derive(Block, Clone)]
41pub struct ReadFile {
42    /// The path to the file to read from.
43    #[input]
44    pub path: InputPort<String>,
45
46    /// The output message stream.
47    #[output]
48    pub output: OutputPort<Bytes>,
49}
50
51impl ReadFile {
52    pub fn new(path: InputPort<String>, output: OutputPort<Bytes>) -> Self {
53        Self { path, output }
54    }
55
56    pub fn with_system(system: &System) -> Self {
57        use crate::SystemBuilding;
58        Self::new(system.input(), system.output())
59    }
60}
61
62impl Block for ReadFile {
63    fn execute(&mut self, _runtime: &dyn BlockRuntime) -> BlockResult {
64        use std::io::prelude::Read;
65
66        while let Some(path) = self.path.recv()? {
67            let mut file = std::fs::OpenOptions::new().read(true).open(path)?;
68
69            let mut buffer = Vec::new();
70            file.read_to_end(&mut buffer)?;
71            let bytes = Bytes::from(buffer);
72
73            self.output.send(&bytes)?;
74        }
75
76        Ok(())
77    }
78}
79
80#[cfg(feature = "std")]
81impl StdioSystem for ReadFile {
82    fn build_system(config: StdioConfig) -> Result<System, StdioError> {
83        //use crate::{CoreBlocks, SysBlocks, SystemBuilding};
84
85        config.allow_only(vec!["path"])?;
86
87        Ok(System::build(|_s| todo!())) // TODO
88    }
89}
90
91#[cfg(test)]
92mod tests {
93    extern crate std;
94    use super::ReadFile;
95    use crate::{System, SystemBuilding, SystemExecution};
96
97    #[test]
98    fn instantiate_block() {
99        // Check that the block is constructible:
100        let _ = System::build(|s| {
101            let _ = s.block(ReadFile::new(s.input(), s.output()));
102        });
103    }
104
105    #[test]
106    fn run_block() {
107        use protoflow_core::{
108            runtimes::StdRuntime as Runtime, transports::MpscTransport as Transport,
109        };
110        use std::io::Write;
111
112        let mut temp_file = tempfile::NamedTempFile::new().unwrap();
113        let test_content = "Hello, World!\n";
114        temp_file.write_all(test_content.as_bytes()).unwrap();
115
116        let mut system = System::new(&Runtime::new(Transport::new()).unwrap());
117        let read_file = system.block(ReadFile::with_system(&system));
118
119        let mut path = system.output();
120        let output = system.input();
121
122        system.connect(&path, &read_file.path);
123        system.connect(&read_file.output, &output);
124
125        let thrd = std::thread::spawn(move || system.execute().and_then(|p| p.join()).unwrap());
126
127        path.send(&temp_file.path().to_string_lossy().into())
128            .unwrap();
129
130        assert_eq!(
131            output
132                .recv()
133                .expect("should receive output")
134                .expect("output shouldn't be None"),
135            test_content
136        );
137
138        path.close().unwrap();
139
140        assert_eq!(
141            output.recv(),
142            Ok(None),
143            "want EOS signal after path port is closed"
144        );
145
146        thrd.join().unwrap()
147    }
148}
protoflow_blocks/blocks/sys/read_file.rs

protoflow_blocks/blocks/sys/
read_file.rs
