71 lines
1.8 KiB
Rust
71 lines
1.8 KiB
Rust
//! Context management
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use alloc::arc::Arc;
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use collections::{BTreeMap, Vec};
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use spin::{Once, RwLock, RwLockReadGuard, RwLockWriteGuard};
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/// File operations
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pub mod file;
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/// Maximum context files
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pub const CONTEXT_MAX_FILES: usize = 65536;
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/// Context ID
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pub type ContextId = u16;
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/// Context list type
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pub type ContextList = BTreeMap<ContextId, Arc<RwLock<Context>>>;
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/// Contexts list
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static CONTEXTS: Once<RwLock<ContextList>> = Once::new();
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/// Initialize contexts, called if needed
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fn init_contexts() -> RwLock<ContextList> {
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let mut map: ContextList = BTreeMap::new();
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map.insert(0, Arc::new(RwLock::new(Context::new())));
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RwLock::new(map)
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}
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/// Get the global schemes list, const
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pub fn contexts() -> RwLockReadGuard<'static, ContextList> {
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CONTEXTS.call_once(init_contexts).read()
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}
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/// Get the global schemes list, mutable
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pub fn contexts_mut() -> RwLockWriteGuard<'static, ContextList> {
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CONTEXTS.call_once(init_contexts).write()
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}
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/// A context, which identifies either a process or a thread
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#[derive(Debug)]
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pub struct Context {
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/// The open files in the scheme
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pub files: Vec<Option<file::File>>
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}
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impl Context {
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pub fn new() -> Context {
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Context {
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files: Vec::new()
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}
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}
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/// Add a file to the lowest available slot.
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/// Return the file descriptor number or None if no slot was found
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pub fn add_file(&mut self, file: file::File) -> Option<usize> {
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for (i, mut file_option) in self.files.iter_mut().enumerate() {
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if file_option.is_none() {
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*file_option = Some(file);
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return Some(i);
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}
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}
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let len = self.files.len();
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if len < CONTEXT_MAX_FILES {
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self.files.push(Some(file));
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Some(len)
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} else {
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None
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}
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}
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}
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