126 lines
3.6 KiB
Rust
126 lines
3.6 KiB
Rust
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use error::{StoreError, StoreErrorKind};
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use std::io::{Seek, SeekFrom};
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use std::path::{Path, PathBuf};
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use std::fs::{File, OpenOptions, create_dir_all};
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/// `LazyFile` type
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///
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/// A lazy file is either absent, but a path to it is available, or it is present.
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#[derive(Debug)]
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pub enum LazyFile {
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Absent(PathBuf),
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File(File)
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}
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fn open_file<A: AsRef<Path>>(p: A) -> ::std::io::Result<File> {
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OpenOptions::new().write(true).read(true).open(p)
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}
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fn create_file<A: AsRef<Path>>(p: A) -> ::std::io::Result<File> {
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if let Some(parent) = p.as_ref().parent() {
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debug!("Implicitely creating directory: {:?}", parent);
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if let Err(e) = create_dir_all(parent) {
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return Err(e);
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}
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}
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OpenOptions::new().write(true).read(true).create(true).open(p)
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}
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impl LazyFile {
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/**
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* Get the mutable file behind a LazyFile object
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*/
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pub fn get_file_mut(&mut self) -> Result<&mut File, StoreError> {
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debug!("Getting lazy file: {:?}", self);
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let file = match *self {
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LazyFile::File(ref mut f) => return {
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// We seek to the beginning of the file since we expect each
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// access to the file to be in a different context
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f.seek(SeekFrom::Start(0))
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.map_err(|e| StoreError::new(StoreErrorKind::FileNotCreated, Some(Box::new(e))))
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.map(|_| f)
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},
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LazyFile::Absent(ref p) => {
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try!(open_file(p).map_err(|e| {
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StoreError::new(StoreErrorKind::FileNotFound,
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Some(Box::new(e)))
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}))
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}
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};
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*self = LazyFile::File(file);
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if let LazyFile::File(ref mut f) = *self {
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return Ok(f);
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}
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unreachable!()
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}
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/**
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* Create a file out of this LazyFile object
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*/
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pub fn create_file(&mut self) -> Result<&mut File, StoreError> {
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debug!("Creating lazy file: {:?}", self);
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let file = match *self {
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LazyFile::File(ref mut f) => return Ok(f),
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LazyFile::Absent(ref p) => {
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try!(create_file(p).map_err(|e| {
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StoreError::new(StoreErrorKind::FileNotFound,
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Some(Box::new(e)))
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}))
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}
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};
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*self = LazyFile::File(file);
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if let LazyFile::File(ref mut f) = *self {
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return Ok(f);
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}
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unreachable!()
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}
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}
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#[cfg(test)]
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mod test {
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use super::LazyFile;
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use std::io::{Read, Write};
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use std::path::PathBuf;
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use tempdir::TempDir;
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fn get_dir() -> TempDir {
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TempDir::new("test-image").unwrap()
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}
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#[test]
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fn lazy_file() {
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let dir = get_dir();
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let mut path = PathBuf::from(dir.path());
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path.set_file_name("test1");
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let mut lf = LazyFile::Absent(path);
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write!(lf.create_file().unwrap(), "Hello World").unwrap();
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dir.close().unwrap();
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}
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#[test]
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fn lazy_file_with_file() {
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let dir = get_dir();
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let mut path = PathBuf::from(dir.path());
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path.set_file_name("test2");
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let mut lf = LazyFile::Absent(path.clone());
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{
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let mut file = lf.create_file().unwrap();
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file.write(b"Hello World").unwrap();
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file.sync_all().unwrap();
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}
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{
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let mut file = lf.get_file_mut().unwrap();
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let mut s = Vec::new();
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file.read_to_end(&mut s).unwrap();
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assert_eq!(s, "Hello World".to_string().into_bytes());
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}
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dir.close().unwrap();
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}
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}
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