Solve PaaS I/O

rust/paasio/.exercism/config.json

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+{
+  "authors": [
+    "coriolinus"
+  ],
+  "contributors": [
+    "ccouzens",
+    "ClashTheBunny",
+    "cwhakes",
+    "efx",
+    "ErikSchierboom",
+    "petertseng",
+    "rofrol",
+    "shenek",
+    "stringparser",
+    "TheDarkula",
+    "ZapAnton"
+  ],
+  "files": {
+    "solution": [
+      "src/lib.rs",
+      "Cargo.toml"
+    ],
+    "test": [
+      "tests/paasio.rs"
+    ],
+    "example": [
+      ".meta/example.rs"
+    ]
+  },
+  "blurb": "Report network IO statistics.",
+  "source": "Brian Matsuo",
+  "source_url": "https://github.com/bmatsuo",
+  "custom": {
+    "ignore-count-ignores": true
+  }
+}

rust/paasio/.exercism/metadata.json

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+{"track":"rust","exercise":"paasio","id":"a827ee447ff84e34896c51b5fb1eca9a","url":"https://exercism.org/tracks/rust/exercises/paasio","handle":"averywinters","is_requester":true,"auto_approve":false}

rust/paasio/.gitignore

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+# Generated by Cargo
+# will have compiled files and executables
+/target/
+**/*.rs.bk
+
+# Remove Cargo.lock from gitignore if creating an executable, leave it for libraries
+# More information here http://doc.crates.io/guide.html#cargotoml-vs-cargolock
+Cargo.lock

rust/paasio/Cargo.toml

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+[package]
+edition = "2021"
+name = "paasio"
+version = "0.0.0"

rust/paasio/HELP.md

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+# Help
+
+## Running the tests
+
+Execute the tests with:
+
+```bash
+$ cargo test
+```
+
+All but the first test have been ignored. After you get the first test to
+pass, open the tests source file which is located in the `tests` directory
+and remove the `#[ignore]` flag from the next test and get the tests to pass
+again. Each separate test is a function with `#[test]` flag above it.
+Continue, until you pass every test.
+
+If you wish to run _only ignored_ tests without editing the tests source file, use:
+
+```bash
+$ cargo test -- --ignored
+```
+
+If you are using Rust 1.51 or later, you can run _all_ tests with
+
+```bash
+$ cargo test -- --include-ignored
+```
+
+To run a specific test, for example `some_test`, you can use:
+
+```bash
+$ cargo test some_test
+```
+
+If the specific test is ignored, use:
+
+```bash
+$ cargo test some_test -- --ignored
+```
+
+To learn more about Rust tests refer to the online [test documentation][rust-tests].
+
+[rust-tests]: https://doc.rust-lang.org/book/ch11-02-running-tests.html
+
+## Submitting your solution
+
+You can submit your solution using the `exercism submit src/lib.rs Cargo.toml` command.
+This command will upload your solution to the Exercism website and print the solution page's URL.
+
+It's possible to submit an incomplete solution which allows you to:
+
+- See how others have completed the exercise
+- Request help from a mentor
+
+## Need to get help?
+
+If you'd like help solving the exercise, check the following pages:
+
+- The [Rust track's documentation](https://exercism.org/docs/tracks/rust)
+- The [Rust track's programming category on the forum](https://forum.exercism.org/c/programming/rust)
+- [Exercism's programming category on the forum](https://forum.exercism.org/c/programming/5)
+- The [Frequently Asked Questions](https://exercism.org/docs/using/faqs)
+
+Should those resources not suffice, you could submit your (incomplete) solution to request mentoring.
+
+## Rust Installation
+
+Refer to the [exercism help page][help-page] for Rust installation and learning
+resources.
+
+## Submitting the solution
+
+Generally you should submit all files in which you implemented your solution (`src/lib.rs` in most cases). If you are using any external crates, please consider submitting the `Cargo.toml` file. This will make the review process faster and clearer.
+
+## Feedback, Issues, Pull Requests
+
+The GitHub [track repository][github] is the home for all of the Rust exercises. If you have feedback about an exercise, or want to help implement new exercises, head over there and create an issue. Members of the rust track team are happy to help!
+
+If you want to know more about Exercism, take a look at the [contribution guide].
+
+## Submitting Incomplete Solutions
+It's possible to submit an incomplete solution so you can see how others have completed the exercise.
+
+[help-page]: https://exercism.org/tracks/rust/learning
+[github]: https://github.com/exercism/rust
+[contribution guide]: https://exercism.org/docs/community/contributors

rust/paasio/README.md

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+# PaaS I/O
+
+Welcome to PaaS I/O on Exercism's Rust Track.
+If you need help running the tests or submitting your code, check out `HELP.md`.
+
+## Instructions
+
+Report network IO statistics.
+
+You are writing a [PaaS][paas], and you need a way to bill customers based on network and filesystem usage.
+
+Create a wrapper for network connections and files that can report IO statistics.
+The wrapper must report:
+
+- The total number of bytes read/written.
+- The total number of read/write operations.
+
+[paas]: https://en.wikipedia.org/wiki/Platform_as_a_service
+
+Network and file operations are implemented in terms of the [`io::Read`][read] and [`io::Write`][write] traits. It will therefore be necessary to implement those traits for your types.
+
+[read]: https://doc.rust-lang.org/std/io/trait.Read.html
+[write]: https://doc.rust-lang.org/std/io/trait.Write.html
+
+## Source
+
+### Created by
+
+- @coriolinus
+
+### Contributed to by
+
+- @ccouzens
+- @ClashTheBunny
+- @cwhakes
+- @efx
+- @ErikSchierboom
+- @petertseng
+- @rofrol
+- @shenek
+- @stringparser
+- @TheDarkula
+- @ZapAnton
+
+### Based on
+
+Brian Matsuo - https://github.com/bmatsuo

rust/paasio/src/lib.rs

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+use ::std::io::{Read, Result, Write};
+
+pub struct ReadStats<R> {
+    read: R,
+    bytes_through: usize,
+    reads: usize,
+}
+
+impl<R: Read> ReadStats<R> {
+    pub fn new(read: R) -> ReadStats<R> {
+        ReadStats {
+            read,
+            bytes_through: 0,
+            reads: 0,
+        }
+    }
+
+    pub fn get_ref(&self) -> &R {
+        &self.read
+    }
+
+    pub fn bytes_through(&self) -> usize {
+        self.bytes_through
+    }
+
+    pub fn reads(&self) -> usize {
+        self.reads
+    }
+}
+
+impl<R: Read> Read for ReadStats<R> {
+    fn read(&mut self, buf: &mut [u8]) -> Result<usize> {
+        let len = self.read.read(buf)?;
+        self.reads += 1;
+        self.bytes_through += len;
+        Ok(len)
+    }
+
+    // To be most efficient, we would implement all the provided methods as well.
+}
+
+pub struct WriteStats<W> {
+    write: W,
+    bytes_through: usize,
+    writes: usize,
+}
+
+impl<W: Write> WriteStats<W> {
+    pub fn new(write: W) -> WriteStats<W> {
+        WriteStats {
+            write,
+            bytes_through: 0,
+            writes: 0,
+        }
+    }
+
+    pub fn get_ref(&self) -> &W {
+        &self.write
+    }
+
+    pub fn bytes_through(&self) -> usize {
+        self.bytes_through
+    }
+
+    pub fn writes(&self) -> usize {
+        self.writes
+    }
+}
+
+impl<W: Write> Write for WriteStats<W> {
+    fn write(&mut self, buf: &[u8]) -> Result<usize> {
+        let len = self.write.write(buf)?;
+        self.writes += 1;
+        self.bytes_through += len;
+        Ok(len)
+    }
+
+    fn flush(&mut self) -> Result<()> {
+        self.write.flush()
+    }
+
+    // To be most efficient, we would implement all the provided methods as well.
+}

rust/paasio/tests/paasio.rs

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+/// test a few read scenarios
+macro_rules! test_read {
+    ($(#[$attr:meta])* $modname:ident ($input:expr, $len:expr)) => {
+        mod $modname {
+            use std::io::{Read, BufReader};
+            use paasio::*;
+
+            const CHUNK_SIZE: usize = 2;
+
+            $(#[$attr])*
+            #[test]
+            fn read_passthrough() {
+                let data = $input;
+                let len = $len;
+                let size = len(&data);
+                let mut reader = ReadStats::new(data);
+
+                let mut buffer = Vec::with_capacity(size);
+                let qty_read = reader.read_to_end(&mut buffer);
+
+                assert!(qty_read.is_ok());
+                assert_eq!(size, qty_read.unwrap());
+                assert_eq!(size, buffer.len());
+                // 2: first to read all the data, second to check that
+                // there wasn't any more pending data which simply didn't
+                // fit into the existing buffer
+                assert_eq!(2, reader.reads());
+                assert_eq!(size, reader.bytes_through());
+            }
+
+            $(#[$attr])*
+            #[test]
+            fn read_chunks() {
+                let data = $input;
+                let len = $len;
+                let size = len(&data);
+                let mut reader = ReadStats::new(data);
+
+                let mut buffer = [0_u8; CHUNK_SIZE];
+                let mut chunks_read = 0;
+                while reader.read(&mut buffer[..]).unwrap_or_else(|_| panic!("read failed at chunk {}", chunks_read+1)) > 0 {
+                    chunks_read += 1;
+                }
+
+                assert_eq!(size / CHUNK_SIZE + std::cmp::min(1, size % CHUNK_SIZE), chunks_read);
+                // we read once more than the number of chunks, because the final
+                // read returns 0 new bytes
+                assert_eq!(1+chunks_read, reader.reads());
+                assert_eq!(size, reader.bytes_through());
+            }
+
+            $(#[$attr])*
+            #[test]
+            fn read_buffered_chunks() {
+                let data = $input;
+                let len = $len;
+                let size = len(&data);
+                let mut reader = BufReader::new(ReadStats::new(data));
+
+                let mut buffer = [0_u8; CHUNK_SIZE];
+                let mut chunks_read = 0;
+                while reader.read(&mut buffer[..]).unwrap_or_else(|_| panic!("read failed at chunk {}", chunks_read+1)) > 0 {
+                    chunks_read += 1;
+                }
+
+                assert_eq!(size / CHUNK_SIZE + std::cmp::min(1, size % CHUNK_SIZE), chunks_read);
+                // the BufReader should smooth out the reads, collecting into
+                // a buffer and performing only two read operations:
+                // the first collects everything into the buffer,
+                // and the second ensures that no data remains
+                assert_eq!(2, reader.get_ref().reads());
+                assert_eq!(size, reader.get_ref().bytes_through());
+            }
+        }
+    };
+}
+
+/// test a few write scenarios
+macro_rules! test_write {
+    ($(#[$attr:meta])* $modname:ident ($input:expr, $len:expr)) => {
+        mod $modname {
+            use std::io::{self, Write, BufWriter};
+            use paasio::*;
+
+            const CHUNK_SIZE: usize = 2;
+            $(#[$attr])*
+            #[test]
+            fn write_passthrough() {
+                let data = $input;
+                let len = $len;
+                let size = len(&data);
+                let mut writer = WriteStats::new(Vec::with_capacity(size));
+                let written = writer.write(data);
+                assert!(written.is_ok());
+                assert_eq!(size, written.unwrap());
+                assert_eq!(size, writer.bytes_through());
+                assert_eq!(1, writer.writes());
+                assert_eq!(data, writer.get_ref().as_slice());
+            }
+
+            $(#[$attr])*
+            #[test]
+            fn sink_oneshot() {
+                let data = $input;
+                let len = $len;
+                let size = len(&data);
+                let mut writer = WriteStats::new(io::sink());
+                let written = writer.write(data);
+                assert!(written.is_ok());
+                assert_eq!(size, written.unwrap());
+                assert_eq!(size, writer.bytes_through());
+                assert_eq!(1, writer.writes());
+            }
+
+            $(#[$attr])*
+            #[test]
+            fn sink_windowed() {
+                let data = $input;
+                let len = $len;
+                let size = len(&data);
+                let mut writer = WriteStats::new(io::sink());
+
+                let mut chunk_count = 0;
+                for chunk in data.chunks(CHUNK_SIZE) {
+                    chunk_count += 1;
+                    let written = writer.write(chunk);
+                    assert!(written.is_ok());
+                    assert_eq!(CHUNK_SIZE, written.unwrap());
+                }
+                assert_eq!(size, writer.bytes_through());
+                assert_eq!(chunk_count, writer.writes());
+            }
+
+            $(#[$attr])*
+            #[test]
+            fn sink_buffered_windowed() {
+                let data = $input;
+                let len = $len;
+                let size = len(&data);
+                let mut writer = BufWriter::new(WriteStats::new(io::sink()));
+
+                for chunk in data.chunks(CHUNK_SIZE) {
+                    let written = writer.write(chunk);
+                    assert!(written.is_ok());
+                    assert_eq!(CHUNK_SIZE, written.unwrap());
+                }
+                // at this point, nothing should have yet been passed through to
+                // our writer
+                assert_eq!(0, writer.get_ref().bytes_through());
+                assert_eq!(0, writer.get_ref().writes());
+
+                // after flushing, everything should pass through in one go
+                assert!(writer.flush().is_ok());
+                assert_eq!(size, writer.get_ref().bytes_through());
+                assert_eq!(1, writer.get_ref().writes());
+            }
+        }
+    };
+}
+
+#[test]
+fn create_stats() {
+    let mut data: Vec<u8> = Vec::new();
+    let _ = paasio::ReadStats::new(data.as_slice());
+    let _ = paasio::WriteStats::new(data.as_mut_slice());
+}
+
+test_read!(#[ignore] read_string (
+    "Twas brillig, and the slithy toves/Did gyre and gimble in the wabe:/All mimsy were the borogoves,/And the mome raths outgrabe.".as_bytes(),
+    |d: &[u8]| d.len()
+));
+test_write!(#[ignore] write_string (
+    "Beware the Jabberwock, my son!/The jaws that bite, the claws that catch!/Beware the Jubjub bird, and shun/The frumious Bandersnatch!".as_bytes(),
+    |d: &[u8]| d.len()
+));
+
+test_read!(
+        read_byte_literal(
+        &[1_u8, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144][..],
+        |d: &[u8]| d.len()
+    )
+);
+test_write!(
+        write_byte_literal(
+        &[2_u8, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61,][..],
+        |d: &[u8]| d.len()
+    )
+);
+
+test_read!(
+        read_file(
+        ::std::fs::File::open("Cargo.toml").expect("Cargo.toml must be present"),
+        |f: &::std::fs::File| f.metadata().expect("metadata must be present").len() as usize
+    )
+);
+
+#[test]
+fn read_stats_by_ref_returns_wrapped_reader() {
+    use paasio::ReadStats;
+
+    let input =
+        "Why, sometimes I've believed as many as six impossible things before breakfast".as_bytes();
+    let reader = ReadStats::new(input);
+    assert_eq!(reader.get_ref(), &input);
+}