555 lines
17 KiB
Rust
555 lines
17 KiB
Rust
//! A wrapper around an object that ties it to a physical file
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pub mod error;
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pub mod constants;
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use anyhow::{anyhow, Context};
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use constants::data_format::DataFormat;
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use error::Error;
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use log::info;
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use serde::{de::DeserializeOwned, Serialize};
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use std::{
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fs::{copy, remove_file, File},
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io::{ErrorKind, Write},
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path::{Path, PathBuf},
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thread,
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thread::JoinHandle,
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};
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/// A wrapper around an object `T` that ties the object to a physical file
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#[derive(Debug)]
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pub struct FileLinked<T>
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where
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T: Serialize,
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{
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val: T,
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path: PathBuf,
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temp_file_path: PathBuf,
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file_thread: Option<JoinHandle<()>>,
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data_format: DataFormat,
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}
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impl<T> Drop for FileLinked<T>
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where
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T: Serialize,
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{
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fn drop(&mut self) {
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if let Some(file_thread) = self.file_thread.take() {
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file_thread
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.join()
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.expect("Error cleaning up file thread for file_linked object");
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}
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}
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}
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impl<T> FileLinked<T>
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where
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T: Serialize,
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{
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/// Returns a readonly reference of `T`
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///
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/// # Examples
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/// ```
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/// # use file_linked::*;
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/// # use file_linked::constants::data_format::DataFormat;
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/// # use serde::{Deserialize, Serialize};
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/// # use std::fmt;
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/// # use std::string::ToString;
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/// # use std::path::PathBuf;
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/// #
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/// # #[derive(Deserialize, Serialize)]
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/// # struct Test {
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/// # pub a: u32,
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/// # pub b: String,
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/// # pub c: f64
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/// # }
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/// #
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/// # fn main() {
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/// let test = Test {
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/// a: 1,
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/// b: String::from("two"),
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/// c: 3.0
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/// };
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///
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/// let linked_test = FileLinked::new(test, &PathBuf::from("./temp"), DataFormat::Json)
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/// .expect("Unable to create file linked object");
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///
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/// assert_eq!(linked_test.readonly().a, 1);
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/// assert_eq!(linked_test.readonly().b, String::from("two"));
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/// assert_eq!(linked_test.readonly().c, 3.0);
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/// #
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/// # drop(linked_test);
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/// #
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/// # std::fs::remove_file("./temp").expect("Unable to remove file");
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/// # }
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/// ```
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pub fn readonly(&self) -> &T {
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&self.val
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}
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/// Creates a new [`FileLinked`] object of type `T` stored to the file given by `path`.
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///
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/// # Examples
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/// ```
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/// # use file_linked::*;
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/// # use file_linked::constants::data_format::DataFormat;
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/// # use serde::{Deserialize, Serialize};
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/// # use std::fmt;
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/// # use std::string::ToString;
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/// # use std::path::PathBuf;
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/// #
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/// #[derive(Deserialize, Serialize)]
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/// struct Test {
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/// pub a: u32,
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/// pub b: String,
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/// pub c: f64
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/// }
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///
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/// # fn main() {
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/// let test = Test {
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/// a: 1,
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/// b: String::from("two"),
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/// c: 3.0
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/// };
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///
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/// let linked_test = FileLinked::new(test, &PathBuf::from("./temp"), DataFormat::Json)
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/// .expect("Unable to create file linked object");
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///
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/// assert_eq!(linked_test.readonly().a, 1);
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/// assert_eq!(linked_test.readonly().b, String::from("two"));
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/// assert_eq!(linked_test.readonly().c, 3.0);
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/// #
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/// # drop(linked_test);
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/// #
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/// # std::fs::remove_file("./temp").expect("Unable to remove file");
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/// # }
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/// ```
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pub fn new(val: T, path: &Path, data_format: DataFormat) -> Result<FileLinked<T>, Error> {
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let mut temp_file_path = path.to_path_buf();
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temp_file_path.set_file_name(format!(
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".temp{}",
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path.file_name()
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.ok_or_else(|| anyhow!("Unable to get filename for tempfile {}", path.display()))?
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.to_str()
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.ok_or_else(|| anyhow!("Unable to get filename for tempfile {}", path.display()))?
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));
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let mut result = FileLinked {
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val,
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path: path.to_path_buf(),
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temp_file_path,
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file_thread: None,
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data_format
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};
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result.write_data()?;
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Ok(result)
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}
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fn write_data(&mut self) -> Result<(), Error> {
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let thread_path = self.path.clone();
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let thread_temp_path = self.temp_file_path.clone();
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let thread_val = match self.data_format {
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DataFormat::Bincode => bincode::serialize(&self.val)
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.with_context(|| "Unable to serialize object into bincode".to_string())?,
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DataFormat::Json => serde_json::to_vec(&self.val)
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.with_context(|| "Unable to serialize object into JSON".to_string())?,
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};
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if let Some(file_thread) = self.file_thread.take() {
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file_thread
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.join()
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.expect("Error cleaning up file thread for file_linked object");
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}
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match File::open(&self.path) {
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Ok(_) => {
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let handle = thread::spawn(move || {
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copy(&thread_path, &thread_temp_path).expect("Unable to copy temp file");
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let mut file = File::create(&thread_path).expect("Error creating file handle");
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file.write_all(thread_val.as_slice())
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.expect("Failed to write data to file");
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remove_file(&thread_temp_path).expect("Error removing temp file");
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});
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self.file_thread = Some(handle);
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}
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Err(error) if error.kind() == ErrorKind::NotFound => {
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let handle = thread::spawn(move || {
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let mut file = File::create(&thread_path).expect("Error creating file handle");
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file.write_all(thread_val.as_slice())
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.expect("Failed to write data to file");
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});
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self.file_thread = Some(handle);
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}
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Err(error) => return Err(Error::IO(error)),
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}
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Ok(())
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}
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/// Modifies the data contained in a `FileLinked` object using a callback `op` that has a mutable reference to the
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/// underlying data. After the mutable operation is performed the data is written to a file to synchronize the state.
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///
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/// # Examples
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/// ```
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/// # use file_linked::*;
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/// # use file_linked::error::Error;
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/// # use file_linked::constants::data_format::DataFormat;
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/// # use serde::{Deserialize, Serialize};
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/// # use std::fmt;
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/// # use std::string::ToString;
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/// # use std::path::PathBuf;
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/// #
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/// # #[derive(Deserialize, Serialize)]
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/// # struct Test {
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/// # pub a: u32,
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/// # pub b: String,
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/// # pub c: f64
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/// # }
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/// #
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/// # fn main() -> Result<(), Error> {
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/// let test = Test {
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/// a: 1,
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/// b: String::from(""),
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/// c: 0.0
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/// };
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///
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/// let mut linked_test = FileLinked::new(test, &PathBuf::from("./temp"), DataFormat::Bincode)
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/// .expect("Unable to create file linked object");
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///
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/// assert_eq!(linked_test.readonly().a, 1);
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///
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/// linked_test.mutate(|t| t.a = 2)?;
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///
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/// assert_eq!(linked_test.readonly().a, 2);
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/// #
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/// # drop(linked_test);
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/// #
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/// # std::fs::remove_file("./temp").expect("Unable to remove file");
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/// #
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/// # Ok(())
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/// # }
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/// ```
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pub fn mutate<U, F: FnOnce(&mut T) -> U>(&mut self, op: F) -> Result<U, Error> {
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let result = op(&mut self.val);
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self.write_data()?;
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Ok(result)
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}
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/// Replaces the value held by the `FileLinked` object with `val`. After replacing the object will be written to a file.
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///
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/// # Examples
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/// ```
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/// # use file_linked::*;
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/// # use file_linked::error::Error;
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/// # use file_linked::constants::data_format::DataFormat;
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/// # use serde::{Deserialize, Serialize};
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/// # use std::fmt;
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/// # use std::string::ToString;
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/// # use std::path::PathBuf;
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/// #
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/// # #[derive(Deserialize, Serialize)]
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/// # struct Test {
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/// # pub a: u32,
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/// # pub b: String,
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/// # pub c: f64
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/// # }
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/// #
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/// # fn main() -> Result<(), Error> {
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/// let test = Test {
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/// a: 1,
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/// b: String::from(""),
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/// c: 0.0
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/// };
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///
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/// let mut linked_test = FileLinked::new(test, &PathBuf::from("./temp"), DataFormat::Bincode)
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/// .expect("Unable to create file linked object");
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///
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/// assert_eq!(linked_test.readonly().a, 1);
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///
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/// linked_test.replace(Test {
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/// a: 2,
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/// b: String::from(""),
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/// c: 0.0
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/// })?;
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///
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/// assert_eq!(linked_test.readonly().a, 2);
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/// #
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/// # drop(linked_test);
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/// #
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/// # std::fs::remove_file("./temp").expect("Unable to remove file");
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/// #
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/// # Ok(())
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/// # }
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/// ```
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pub fn replace(&mut self, val: T) -> Result<(), Error> {
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self.val = val;
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self.write_data()
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}
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}
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impl<T> FileLinked<T>
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where
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T: Serialize + DeserializeOwned,
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{
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/// Deserializes an object `T` from the file given by `path`
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///
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/// # Examples
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/// ```
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/// # use file_linked::*;
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/// # use file_linked::error::Error;
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/// # use file_linked::constants::data_format::DataFormat;
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/// # use serde::{Deserialize, Serialize};
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/// # use std::fmt;
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/// # use std::string::ToString;
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/// # use std::fs;
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/// # use std::fs::OpenOptions;
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/// # use std::io::Write;
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/// # use std::path::PathBuf;
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/// #
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/// # #[derive(Deserialize, Serialize)]
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/// # struct Test {
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/// # pub a: u32,
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/// # pub b: String,
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/// # pub c: f64
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/// # }
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/// #
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/// # fn main() -> Result<(), Error> {
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/// let test = Test {
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/// a: 1,
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/// b: String::from("2"),
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/// c: 3.0
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/// };
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///
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/// let path = PathBuf::from("./temp");
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///
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/// let mut file = OpenOptions::new()
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/// .write(true)
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/// .create(true)
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/// .open(&path)
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/// .expect("Unable to create file");
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///
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/// bincode::serialize_into(file, &test).expect("Unable to serialize object");
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///
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/// let mut linked_test = FileLinked::<Test>::from_file(&path, DataFormat::Bincode)
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/// .expect("Unable to create file linked object");
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///
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/// assert_eq!(linked_test.readonly().a, test.a);
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/// assert_eq!(linked_test.readonly().b, test.b);
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/// assert_eq!(linked_test.readonly().c, test.c);
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/// #
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/// # drop(linked_test);
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/// #
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/// # std::fs::remove_file("./temp").expect("Unable to remove file");
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/// #
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/// # Ok(())
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/// # }
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/// ```
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pub fn from_file(path: &Path, data_format: DataFormat) -> Result<FileLinked<T>, Error> {
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let mut temp_file_path = path.to_path_buf();
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temp_file_path.set_file_name(format!(
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".temp{}",
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path.file_name()
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.ok_or_else(|| anyhow!("Unable to get filename for tempfile {}", path.display()))?
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.to_str()
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.ok_or_else(|| anyhow!("Unable to get filename for tempfile {}", path.display()))?
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));
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match File::open(path).map_err(Error::from).and_then(|file| {
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match data_format {
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DataFormat::Bincode => bincode::deserialize_from::<File, T>(file)
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.with_context(|| format!("Unable to deserialize file {}", path.display()))
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.map_err(Error::from),
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DataFormat::Json => serde_json::from_reader(file)
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.with_context(|| format!("Unable to deserialize file {}", path.display()))
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.map_err(Error::from),
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}
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}) {
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Ok(val) => Ok(FileLinked {
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val,
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path: path.to_path_buf(),
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temp_file_path,
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file_thread: None,
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data_format,
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}),
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Err(err) => {
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info!(
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"Unable to read/deserialize file {} attempting to open temp file {}",
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path.display(),
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temp_file_path.display()
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);
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// Try to use temp file instead and see if that file exists and is serializable
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let val = FileLinked::from_temp_file(&temp_file_path, path, &data_format)
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.map_err(|_| err)
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.with_context(|| format!("Failed to read/deserialize the object from the file {} and temp file {}", path.display(), temp_file_path.display()))?;
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Ok(FileLinked {
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val,
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path: path.to_path_buf(),
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temp_file_path,
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file_thread: None,
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data_format,
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})
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}
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}
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}
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fn from_temp_file(temp_file_path: &Path, path: &Path, data_format: &DataFormat) -> Result<T, Error> {
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let file = File::open(temp_file_path)
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.with_context(|| format!("Unable to open file {}", temp_file_path.display()))?;
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let val = match data_format {
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DataFormat::Bincode => bincode::deserialize_from(file).with_context(|| {
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format!(
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"Could not deserialize from temp file {}",
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temp_file_path.display()
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)
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})?,
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DataFormat::Json => serde_json::from_reader(file).with_context(|| {
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format!(
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"Could not deserialize from temp file {}",
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temp_file_path.display()
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)
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})?,
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};
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info!("Successfully deserialized value from temp file");
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copy(temp_file_path, path)?;
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remove_file(temp_file_path)
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.with_context(|| format!("Unable to remove temp file {}", temp_file_path.display()))?;
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Ok(val)
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}
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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use std::{fs, fs::File};
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struct CleanUp {
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path: PathBuf,
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}
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impl CleanUp {
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fn new(path: &Path) -> CleanUp {
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CleanUp {
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path: path.to_path_buf(),
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}
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}
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pub fn run<F: FnOnce(&Path) -> Result<(), Error>>(&self, op: F) -> Result<(), Error> {
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op(&self.path)
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}
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}
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impl Drop for CleanUp {
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fn drop(&mut self) {
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if self.path.exists() {
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fs::remove_file(&self.path).expect("Unable to remove file");
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}
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}
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}
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#[test]
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fn test_readonly() -> Result<(), Error> {
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let path = PathBuf::from("test_readonly");
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let cleanup = CleanUp::new(&path);
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cleanup.run(|p| {
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let val = vec!["one", "two", ""];
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let linked_object = FileLinked::new(val.clone(), &p, DataFormat::Json)?;
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assert_eq!(*linked_object.readonly(), val);
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Ok(())
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})
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}
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|
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#[test]
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fn test_new() -> Result<(), Error> {
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let path = PathBuf::from("test_new");
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let cleanup = CleanUp::new(&path);
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cleanup.run(|p| {
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let val = "test";
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FileLinked::new(val, &p, DataFormat::Bincode)?;
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let file = File::open(&p)?;
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let result: String =
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bincode::deserialize_from(file).expect("Unable to deserialize from file");
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assert_eq!(result, val);
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Ok(())
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})
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}
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#[test]
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fn test_mutate() -> Result<(), Error> {
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let path = PathBuf::from("test_mutate");
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let cleanup = CleanUp::new(&path);
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cleanup.run(|p| {
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let list = vec![1, 2, 3, 4];
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let mut file_linked_list = FileLinked::new(list, &p, DataFormat::Json)?;
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assert_eq!(*file_linked_list.readonly(), vec![1, 2, 3, 4]);
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file_linked_list.mutate(|v1| v1.push(5))?;
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assert_eq!(*file_linked_list.readonly(), vec![1, 2, 3, 4, 5]);
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file_linked_list.mutate(|v1| v1[1] = 1)?;
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assert_eq!(*file_linked_list.readonly(), vec![1, 1, 3, 4, 5]);
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drop(file_linked_list);
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Ok(())
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})
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}
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#[test]
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fn test_replace() -> Result<(), Error> {
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let path = PathBuf::from("test_replace");
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let cleanup = CleanUp::new(&path);
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cleanup.run(|p| {
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let val1 = String::from("val1");
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let val2 = String::from("val2");
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let mut file_linked_list = FileLinked::new(val1.clone(), &p, DataFormat::Bincode)?;
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assert_eq!(*file_linked_list.readonly(), val1);
|
|
|
|
file_linked_list.replace(val2.clone())?;
|
|
assert_eq!(*file_linked_list.readonly(), val2);
|
|
|
|
drop(file_linked_list);
|
|
Ok(())
|
|
})
|
|
}
|
|
|
|
#[test]
|
|
fn test_from_file() -> Result<(), Error> {
|
|
let path = PathBuf::from("test_from_file");
|
|
let cleanup = CleanUp::new(&path);
|
|
cleanup.run(|p| {
|
|
let value: Vec<f64> = vec![2.0, 3.0, 5.0];
|
|
let file = File::create(&p)?;
|
|
|
|
bincode::serialize_into(&file, &value).expect("Unable to serialize into file");
|
|
drop(file);
|
|
|
|
let linked_object: FileLinked<Vec<f64>> = FileLinked::from_file(&p, DataFormat::Bincode)?;
|
|
assert_eq!(*linked_object.readonly(), value);
|
|
|
|
drop(linked_object);
|
|
Ok(())
|
|
})
|
|
}
|
|
}
|