ligmars/
shm_file.rs

1//!Trait used for access to a memory-mapped SHM file, as well as implementations.
2
3/// Trait for a handle to shared memory of some kind, through which
4/// interprocess communication can take place.
5pub trait ShmFileHandle {
6    fn get_mut_ptr(&mut self) -> *mut std::ffi::c_void;
7    fn get_size(&self) -> usize;
8}
9
10cfg_if::cfg_if! {
11    if #[cfg(feature = "internal_shm_impl")] {
12        use std::fs::OpenOptions;
13
14        use memmap2::MmapOptions;
15
16        use crate::error;
17        /// ShmFile holds a pointer to a memory mapped SHM file along with associated metadata
18        pub struct ShmFile {
19            pub file_path: std::path::PathBuf,
20            pub file_size: u64,
21            mapped: memmap2::MmapRaw,
22        }
23
24        impl ShmFile {
25            /// Opens an existing SHM file found at the provided path, and maps it into memory.
26            pub fn open(file_path: std::path::PathBuf) -> error::LGMPResult<Self> {
27                let file = OpenOptions::new()
28                    .read(true)
29                    .write(true)
30                    .create(false)
31                    .open(&file_path)?;
32
33                let file_size = file.metadata()?.len();
34
35                let mapped = MmapOptions::new()
36                    .len(file_size.try_into().expect("File length exceeed usize"))
37                    .map_raw(&file)?;
38
39                Ok(ShmFile {
40                    file_path,
41                    file_size,
42                    mapped,
43                })
44            }
45
46            pub fn get_ptr(&self) -> *mut () {
47                self.mapped.as_mut_ptr() as *mut ()
48            }
49        }
50
51        impl ShmFileHandle for ShmFile {
52            fn get_mut_ptr(&mut self) -> *mut std::ffi::c_void {
53                self.get_ptr() as *mut std::ffi::c_void
54            }
55
56            fn get_size(&self) -> usize {
57                usize::try_from(self.file_size).expect("File size exceeded maxint")
58            }
59        }
60    }
61
62}
63
64pub use shared_memory;
65
66impl ShmFileHandle for shared_memory::Shmem {
67    fn get_mut_ptr(&mut self) -> *mut std::ffi::c_void {
68        self.as_ptr() as *mut std::ffi::c_void
69    }
70
71    fn get_size(&self) -> usize {
72        self.len()
73    }
74}
ligmars/shm_file.rs

ligmars/
shm_file.rs
