[−][src]Struct zbox::File
A reference to an opened file in the repository.
An instance of a File
can be read and/or written depending on what options
it was opened with. Files also implement Seek
to alter the logical
cursor that the file contains internally.
Files are automatically closed when they go out of scope.
As ZboxFS internally cached file content, it is no need to use buffered
reader, such as BufReader<R>
.
Examples
Create a new file and write bytes to it:
use std::io::prelude::*; let mut file = repo.create_file("/foo.txt")?; file.write_all(b"Hello, world!")?; file.finish()?;
Read the content of a file into a String
:
use std::io::prelude::*; let mut file = repo.open_file("/foo.txt")?; let mut content = String::new(); file.read_to_string(&mut content)?; assert_eq!(content, "Hello, world!");
Versioning
File
contents support up to 255 revision versions. Version
is
immutable once it is created.
By default, the maximum number of versions of a File
is 1
, which is
configurable by version_limit
on both Repo
and File
level. File
level option takes precedence.
After reaching this limit, the oldest Version
will be automatically
deleted after adding a new one.
Version number starts from 1
and continuously increases by 1.
Writing
The file content is cached internally for deduplication and will be handled
automatically, thus calling flush
is not recommended.
File
is multi-versioned, each time updating its content will create a new
permanent Version
. There are two ways of writing data to a file:
-
Multi-part Write
This is done by updating
File
usingWrite
trait multiple times. After all writing operations,finish
must be called to create a new version.Examples
use std::io::prelude::*; use std::io::SeekFrom; let mut file = OpenOptions::new() .create(true) .open(&mut repo, "/foo.txt")?; file.write_all(b"foo ")?; file.write_all(b"bar")?; file.finish()?; let mut content = String::new(); file.seek(SeekFrom::Start(0))?; file.read_to_string(&mut content)?; assert_eq!(content, "foo bar");
-
Single-part Write
This can be done by calling
write_once
, which will callfinish
internally to create a new version.Examples
use std::io::{Read, Seek, SeekFrom}; let mut file = OpenOptions::new() .create(true) .open(&mut repo, "/foo.txt")?; file.write_once(b"foo bar")?; let mut content = String::new(); file.seek(SeekFrom::Start(0))?; file.read_to_string(&mut content)?; assert_eq!(content, "foo bar");
Reading
As File
can contain multiple versions, Read
operation can be
associated with different versions. By default, reading on File
object is
always bound to the latest version. To read a specific version, a
VersionReader
, which supports Read
trait as well, can be used.
Examples
Read the file content while it is in writing, notice that reading is always bound to latest content version.
use std::io::prelude::*; use std::io::SeekFrom; // create a file and write data to it let mut file = OpenOptions::new().create(true).open(&mut repo, "/foo.txt")?; file.write_once(&[1, 2, 3, 4, 5, 6])?; // read the first 2 bytes let mut buf = [0; 2]; file.seek(SeekFrom::Start(0))?; file.read_exact(&mut buf)?; assert_eq!(&buf[..], &[1, 2]); // create a new version, now the file content is [1, 2, 7, 8, 5, 6] file.write_once(&[7, 8])?; // notice that reading is on the latest version file.seek(SeekFrom::Current(-2))?; file.read_exact(&mut buf)?; assert_eq!(&buf[..], &[7, 8]);
Read multiple versions using VersionReader
.
use std::io::prelude::*; // create a file and write 2 versions let mut file = OpenOptions::new() .version_limit(4) .create(true) .open(&mut repo, "/foo.txt")?; file.write_once(b"foo")?; file.write_once(b"bar")?; // get latest version number let curr_ver = file.curr_version()?; // create a version reader and read latest version of content let mut rdr = file.version_reader(curr_ver)?; let mut content = String::new(); rdr.read_to_string(&mut content)?; assert_eq!(content, "foobar"); // create another version reader and read previous version of content let mut rdr = file.version_reader(curr_ver - 1)?; let mut content = String::new(); rdr.read_to_string(&mut content)?; assert_eq!(content, "foo");
Methods
impl File
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pub fn metadata(&self) -> Result<Metadata>
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Queries metadata about the file.
pub fn history(&self) -> Result<Vec<Version>>
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Returns a list of all the file content versions.
pub fn curr_version(&self) -> Result<usize>
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Returns the current content version number.
pub fn version_reader(&self, ver_num: usize) -> Result<VersionReader>
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Get a reader of the specified version.
The returned reader implements Read
trait. To get the version
number, first call history
to get the list of all versions and
then choose the version number from it.
pub fn finish(&mut self) -> Result<()>
[src]
Complete multi-part write to file and create a new version.
Errors
Calling this function without writing data before will return
Error::NotWrite
error.
pub fn write_once(&mut self, buf: &[u8]) -> Result<()>
[src]
Single-part write to file and create a new version.
This function provides a convenient way of combining Write
and
finish
.
pub fn set_len(&mut self, len: usize) -> Result<()>
[src]
Truncates or extends the underlying file, create a new version of
content which size to become size
.
If the size is less than the current content size, then the new
content will be shrunk. If it is greater than the current content size,
then the content will be extended to size
and have all of the
intermediate data filled in with 0s.
Errors
This function will return an error if the file is not opened for writing or not finished writing.
Trait Implementations
impl Debug for File
[src]
impl Read for File
[src]
fn read(&mut self, buf: &mut [u8]) -> Result<usize>
[src]
fn read_vectored(&mut self, bufs: &mut [IoSliceMut]) -> Result<usize, Error>
1.36.0[src]
unsafe fn initializer(&self) -> Initializer
[src]
fn read_to_end(&mut self, buf: &mut Vec<u8>) -> Result<usize, Error>
1.0.0[src]
fn read_to_string(&mut self, buf: &mut String) -> Result<usize, Error>
1.0.0[src]
fn read_exact(&mut self, buf: &mut [u8]) -> Result<(), Error>
1.6.0[src]
fn by_ref(&mut self) -> &mut Self
1.0.0[src]
fn bytes(self) -> Bytes<Self>
1.0.0[src]
fn chain<R>(self, next: R) -> Chain<Self, R> where
R: Read,
1.0.0[src]
R: Read,
fn take(self, limit: u64) -> Take<Self>
1.0.0[src]
impl Write for File
[src]
fn write(&mut self, buf: &[u8]) -> Result<usize>
[src]
fn flush(&mut self) -> Result<()>
[src]
fn write_vectored(&mut self, bufs: &[IoSlice]) -> Result<usize, Error>
1.36.0[src]
fn write_all(&mut self, buf: &[u8]) -> Result<(), Error>
1.0.0[src]
fn write_fmt(&mut self, fmt: Arguments) -> Result<(), Error>
1.0.0[src]
fn by_ref(&mut self) -> &mut Self
1.0.0[src]
impl Seek for File
[src]
Auto Trait Implementations
impl Send for File
impl !Sync for File
impl Unpin for File
impl UnwindSafe for File
impl RefUnwindSafe for File
Blanket Implementations
impl<T, U> Into<U> for T where
U: From<T>,
[src]
U: From<T>,
impl<T> From<T> for T
[src]
impl<T, U> TryFrom<U> for T where
U: Into<T>,
[src]
U: Into<T>,
type Error = Infallible
The type returned in the event of a conversion error.
fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>
[src]
impl<T, U> TryInto<U> for T where
U: TryFrom<T>,
[src]
U: TryFrom<T>,
type Error = <U as TryFrom<T>>::Error
The type returned in the event of a conversion error.
fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>
[src]
impl<T> Borrow<T> for T where
T: ?Sized,
[src]
T: ?Sized,
impl<T> BorrowMut<T> for T where
T: ?Sized,
[src]
T: ?Sized,
fn borrow_mut(&mut self) -> &mut T
[src]
impl<T> Any for T where
T: 'static + ?Sized,
[src]
T: 'static + ?Sized,
impl<R> ReadBytesExt for R where
R: Read + ?Sized,
R: Read + ?Sized,
fn read_u8(&mut self) -> Result<u8, Error>
fn read_i8(&mut self) -> Result<i8, Error>
fn read_u16<T>(&mut self) -> Result<u16, Error> where
T: ByteOrder,
T: ByteOrder,
fn read_i16<T>(&mut self) -> Result<i16, Error> where
T: ByteOrder,
T: ByteOrder,
fn read_u24<T>(&mut self) -> Result<u32, Error> where
T: ByteOrder,
T: ByteOrder,
fn read_i24<T>(&mut self) -> Result<i32, Error> where
T: ByteOrder,
T: ByteOrder,
fn read_u32<T>(&mut self) -> Result<u32, Error> where
T: ByteOrder,
T: ByteOrder,
fn read_i32<T>(&mut self) -> Result<i32, Error> where
T: ByteOrder,
T: ByteOrder,
fn read_u48<T>(&mut self) -> Result<u64, Error> where
T: ByteOrder,
T: ByteOrder,
fn read_i48<T>(&mut self) -> Result<i64, Error> where
T: ByteOrder,
T: ByteOrder,
fn read_u64<T>(&mut self) -> Result<u64, Error> where
T: ByteOrder,
T: ByteOrder,
fn read_i64<T>(&mut self) -> Result<i64, Error> where
T: ByteOrder,
T: ByteOrder,
fn read_u128<T>(&mut self) -> Result<u128, Error> where
T: ByteOrder,
T: ByteOrder,
fn read_i128<T>(&mut self) -> Result<i128, Error> where
T: ByteOrder,
T: ByteOrder,
fn read_uint<T>(&mut self, nbytes: usize) -> Result<u64, Error> where
T: ByteOrder,
T: ByteOrder,
fn read_int<T>(&mut self, nbytes: usize) -> Result<i64, Error> where
T: ByteOrder,
T: ByteOrder,
fn read_uint128<T>(&mut self, nbytes: usize) -> Result<u128, Error> where
T: ByteOrder,
T: ByteOrder,
fn read_int128<T>(&mut self, nbytes: usize) -> Result<i128, Error> where
T: ByteOrder,
T: ByteOrder,
fn read_f32<T>(&mut self) -> Result<f32, Error> where
T: ByteOrder,
T: ByteOrder,
fn read_f64<T>(&mut self) -> Result<f64, Error> where
T: ByteOrder,
T: ByteOrder,
fn read_u16_into<T>(&mut self, dst: &mut [u16]) -> Result<(), Error> where
T: ByteOrder,
T: ByteOrder,
fn read_u32_into<T>(&mut self, dst: &mut [u32]) -> Result<(), Error> where
T: ByteOrder,
T: ByteOrder,
fn read_u64_into<T>(&mut self, dst: &mut [u64]) -> Result<(), Error> where
T: ByteOrder,
T: ByteOrder,
fn read_u128_into<T>(&mut self, dst: &mut [u128]) -> Result<(), Error> where
T: ByteOrder,
T: ByteOrder,
fn read_i8_into(&mut self, dst: &mut [i8]) -> Result<(), Error>
fn read_i16_into<T>(&mut self, dst: &mut [i16]) -> Result<(), Error> where
T: ByteOrder,
T: ByteOrder,
fn read_i32_into<T>(&mut self, dst: &mut [i32]) -> Result<(), Error> where
T: ByteOrder,
T: ByteOrder,
fn read_i64_into<T>(&mut self, dst: &mut [i64]) -> Result<(), Error> where
T: ByteOrder,
T: ByteOrder,
fn read_i128_into<T>(&mut self, dst: &mut [i128]) -> Result<(), Error> where
T: ByteOrder,
T: ByteOrder,
fn read_f32_into<T>(&mut self, dst: &mut [f32]) -> Result<(), Error> where
T: ByteOrder,
T: ByteOrder,
fn read_f32_into_unchecked<T>(&mut self, dst: &mut [f32]) -> Result<(), Error> where
T: ByteOrder,
T: ByteOrder,
fn read_f64_into<T>(&mut self, dst: &mut [f64]) -> Result<(), Error> where
T: ByteOrder,
T: ByteOrder,
fn read_f64_into_unchecked<T>(&mut self, dst: &mut [f64]) -> Result<(), Error> where
T: ByteOrder,
T: ByteOrder,
impl<W> WriteBytesExt for W where
W: Write + ?Sized,
W: Write + ?Sized,
fn write_u8(&mut self, n: u8) -> Result<(), Error>
fn write_i8(&mut self, n: i8) -> Result<(), Error>
fn write_u16<T>(&mut self, n: u16) -> Result<(), Error> where
T: ByteOrder,
T: ByteOrder,
fn write_i16<T>(&mut self, n: i16) -> Result<(), Error> where
T: ByteOrder,
T: ByteOrder,
fn write_u24<T>(&mut self, n: u32) -> Result<(), Error> where
T: ByteOrder,
T: ByteOrder,
fn write_i24<T>(&mut self, n: i32) -> Result<(), Error> where
T: ByteOrder,
T: ByteOrder,
fn write_u32<T>(&mut self, n: u32) -> Result<(), Error> where
T: ByteOrder,
T: ByteOrder,
fn write_i32<T>(&mut self, n: i32) -> Result<(), Error> where
T: ByteOrder,
T: ByteOrder,
fn write_u48<T>(&mut self, n: u64) -> Result<(), Error> where
T: ByteOrder,
T: ByteOrder,
fn write_i48<T>(&mut self, n: i64) -> Result<(), Error> where
T: ByteOrder,
T: ByteOrder,
fn write_u64<T>(&mut self, n: u64) -> Result<(), Error> where
T: ByteOrder,
T: ByteOrder,
fn write_i64<T>(&mut self, n: i64) -> Result<(), Error> where
T: ByteOrder,
T: ByteOrder,
fn write_u128<T>(&mut self, n: u128) -> Result<(), Error> where
T: ByteOrder,
T: ByteOrder,
fn write_i128<T>(&mut self, n: i128) -> Result<(), Error> where
T: ByteOrder,
T: ByteOrder,
fn write_uint<T>(&mut self, n: u64, nbytes: usize) -> Result<(), Error> where
T: ByteOrder,
T: ByteOrder,
fn write_int<T>(&mut self, n: i64, nbytes: usize) -> Result<(), Error> where
T: ByteOrder,
T: ByteOrder,
fn write_uint128<T>(&mut self, n: u128, nbytes: usize) -> Result<(), Error> where
T: ByteOrder,
T: ByteOrder,
fn write_int128<T>(&mut self, n: i128, nbytes: usize) -> Result<(), Error> where
T: ByteOrder,
T: ByteOrder,
fn write_f32<T>(&mut self, n: f32) -> Result<(), Error> where
T: ByteOrder,
T: ByteOrder,
fn write_f64<T>(&mut self, n: f64) -> Result<(), Error> where
T: ByteOrder,
T: ByteOrder,