leveldb/database/
bytes.rs

1use std::slice;
2
3/// Bytes allocated by leveldb
4///
5/// It's basically the same thing as `Box<[u8]>` except that it uses
6/// leveldb_free() as a destructor.
7pub struct Bytes {
8    // We use static reference instead of pointer to inform the compiler that
9    // it can't be null. (Because `NonZero` is unstable now.)
10    bytes: &'static mut u8,
11    size: usize,
12    // Tells the compiler that we own u8
13    _marker: ::std::marker::PhantomData<u8>,
14}
15
16impl Bytes {
17    /// Creates instance of `Bytes` from leveldb-allocated data.
18    ///
19    /// Returns `None` if `ptr` is `null`.
20    ///
21    /// # Safety
22    pub unsafe fn from_raw(ptr: *mut u8, size: usize) -> Option<Self> {
23        if ptr.is_null() {
24            None
25        } else {
26            Some(Bytes {
27                bytes: &mut *ptr,
28                size,
29                _marker: Default::default(),
30            })
31        }
32    }
33
34    /// Creates instance of `Bytes` from leveldb-allocated data without null checking.
35    ///
36    /// # Safety
37    pub unsafe fn from_raw_unchecked(ptr: *mut u8, size: usize) -> Self {
38        Bytes {
39            bytes: &mut *ptr,
40            size,
41            _marker: Default::default(),
42        }
43    }
44}
45
46impl Drop for Bytes {
47    fn drop(&mut self) {
48        unsafe {
49            use libc::c_void;
50
51            cruzbit_leveldb_sys::leveldb_free(self.bytes as *mut u8 as *mut c_void);
52        }
53    }
54}
55
56impl std::ops::Deref for Bytes {
57    type Target = [u8];
58
59    fn deref(&self) -> &Self::Target {
60        unsafe { slice::from_raw_parts(self.bytes, self.size) }
61    }
62}
63
64impl std::ops::DerefMut for Bytes {
65    fn deref_mut(&mut self) -> &mut Self::Target {
66        unsafe { slice::from_raw_parts_mut(self.bytes as *mut u8, self.size) }
67    }
68}
69
70impl std::borrow::Borrow<[u8]> for Bytes {
71    fn borrow(&self) -> &[u8] {
72        self
73    }
74}
75
76impl std::borrow::BorrowMut<[u8]> for Bytes {
77    fn borrow_mut(&mut self) -> &mut [u8] {
78        &mut *self
79    }
80}
81
82impl AsRef<[u8]> for Bytes {
83    fn as_ref(&self) -> &[u8] {
84        self
85    }
86}
87
88impl AsMut<[u8]> for Bytes {
89    fn as_mut(&mut self) -> &mut [u8] {
90        &mut *self
91    }
92}
93
94impl From<Bytes> for Vec<u8> {
95    fn from(bytes: Bytes) -> Self {
96        bytes.as_ref().to_owned()
97    }
98}
99
100impl From<Bytes> for Box<[u8]> {
101    fn from(bytes: Bytes) -> Self {
102        bytes.as_ref().to_owned().into_boxed_slice()
103    }
104}
leveldb/database/bytes.rs

leveldb/database/
bytes.rs
