Use HashMap instead of BTreeMap where possible

This shrinks the kernel from 905840 bytes to 862408 bytes.

src/scheme/acpi.rs

@@ -39,6 +39,7 @@ enum HandleKind {
     ShutdownPipe,
 }
 
+// Using BTreeMap as hashbrown doesn't have a const constructor.
 static HANDLES: RwLock<BTreeMap<usize, Handle>> = RwLock::new(BTreeMap::new());
 static NEXT_FD: AtomicUsize = AtomicUsize::new(0);
 

src/scheme/debug.rs

@@ -18,6 +18,7 @@ struct Handle {
     flags: usize,
 }
 
+// Using BTreeMap as hashbrown doesn't have a const constructor.
 static HANDLES: RwLock<BTreeMap<usize, Handle>> = RwLock::new(BTreeMap::new());
 
 /// Add to the input queue

src/scheme/dtb.rs

@@ -1,7 +1,7 @@
 use core::sync::atomic::{self, AtomicUsize};
 
 use alloc::boxed::Box;
-use alloc::collections::BTreeMap;
+use hashbrown::HashMap;
 use spin::{Once, RwLock};
 
 use crate::dtb::DTB_BINARY;
@@ -30,7 +30,7 @@ struct Handle {
     stat: bool,
 }
 
-static HANDLES: RwLock<BTreeMap<usize, Handle>> = RwLock::new(BTreeMap::new());
+static HANDLES: RwLock<HashMap<usize, Handle>> = RwLock::new(HashMap::new());
 static NEXT_FD: AtomicUsize = AtomicUsize::new(0);
 static DATA: Once<Box<[u8]>> = Once::new();
 static SCHEME_ID: Once<SchemeId> = Once::new();
@@ -157,7 +157,7 @@ impl KernelScheme for DtbScheme {
         let handles = HANDLES.read();
         let handle = handles.get(&id).ok_or(Error::new(EBADF))?;
         buf.copy_exactly(&match handle.kind {
-            HandleKind::RawData =>  { 
+            HandleKind::RawData =>  {
                 let data = DATA.get().ok_or(Error::new(EBADFD))?;
                 Stat {
                     st_mode: MODE_FILE,

src/scheme/irq.rs

@@ -21,6 +21,7 @@ use super::{GlobalSchemes, OpenResult, CallerCtx, calc_seek_offset};
 
 /// IRQ queues
 pub(super) static COUNTS: Mutex<[usize; 224]> = Mutex::new([0; 224]);
+// Using BTreeMap as hashbrown doesn't have a const constructor.
 static HANDLES: RwLock<BTreeMap<usize, Handle>> = RwLock::new(BTreeMap::new());
 
 /// These are IRQs 0..=15 (corresponding to interrupt vectors 32..=47). They are opened without the

src/scheme/itimer.rs

@@ -12,6 +12,7 @@ use super::{KernelScheme, CallerCtx, OpenResult};
 pub struct ITimerScheme;
 
 static NEXT_ID: AtomicUsize = AtomicUsize::new(1);
+// Using BTreeMap as hashbrown doesn't have a const constructor.
 static HANDLES: RwLock<BTreeMap<usize, usize>> = RwLock::new(BTreeMap::new());
 
 impl KernelScheme for ITimerScheme {

src/scheme/mod.rs

@@ -13,6 +13,7 @@ use alloc::{
     sync::Arc,
     vec::Vec,
 };
+use hashbrown::HashMap;
 use syscall::{MunmapFlags, SendFdFlags, EventFlags, SEEK_SET, SEEK_CUR, SEEK_END};
 use core::sync::atomic::AtomicUsize;
 use spin::{Once, RwLock, RwLockReadGuard, RwLockWriteGuard};
@@ -95,7 +96,7 @@ int_like!(SchemeId, usize);
 int_like!(FileHandle, AtomicFileHandle, usize, AtomicUsize);
 
 pub struct SchemeIter<'a> {
-    inner: Option<::alloc::collections::btree_map::Iter<'a, Box<str>, SchemeId>>
+    inner: Option<hashbrown::hash_map::Iter<'a, Box<str>, SchemeId>>
 }
 
 impl<'a> Iterator for SchemeIter<'a> {
@@ -108,8 +109,8 @@ impl<'a> Iterator for SchemeIter<'a> {
 
 /// Scheme list type
 pub struct SchemeList {
-    map: BTreeMap<SchemeId, KernelSchemes>,
-    pub(crate) names: BTreeMap<SchemeNamespace, BTreeMap<Box<str>, SchemeId>>,
+    map: HashMap<SchemeId, KernelSchemes>,
+    pub(crate) names: HashMap<SchemeNamespace, HashMap<Box<str>, SchemeId>>,
     next_ns: usize,
     next_id: usize,
 }
@@ -117,8 +118,8 @@ impl SchemeList {
     /// Create a new scheme list.
     pub fn new() -> Self {
         let mut list = SchemeList {
-            map: BTreeMap::new(),
-            names: BTreeMap::new(),
+            map: HashMap::new(),
+            names: HashMap::new(),
             // Scheme namespaces always start at 1. 0 is a reserved namespace, the null namespace
             next_ns: 1,
             next_id: MAX_GLOBAL_SCHEMES,
@@ -150,7 +151,7 @@ impl SchemeList {
     /// Initialize the null namespace
     fn new_null(&mut self) {
         let ns = SchemeNamespace(0);
-        self.names.insert(ns, BTreeMap::new());
+        self.names.insert(ns, HashMap::new());
 
         //TODO: Only memory: is in the null namespace right now. It should be removed when
         //anonymous mmap's are implemented
@@ -163,7 +164,7 @@ impl SchemeList {
     fn new_ns(&mut self) -> SchemeNamespace {
         let ns = SchemeNamespace(self.next_ns);
         self.next_ns += 1;
-        self.names.insert(ns, BTreeMap::new());
+        self.names.insert(ns, HashMap::new());
 
         self.insert(ns, "", |scheme_id| KernelSchemes::Root(Arc::new(RootScheme::new(ns, scheme_id)))).unwrap();
         self.insert_global(ns, "event", GlobalSchemes::Event).unwrap();

src/scheme/pipe.rs

@@ -19,6 +19,7 @@ use super::{KernelScheme, OpenResult, CallerCtx, GlobalSchemes};
 static PIPE_NEXT_ID: AtomicUsize = AtomicUsize::new(1);
 
 // TODO: SLOB?
+// Using BTreeMap as hashbrown doesn't have a const constructor.
 static PIPES: RwLock<BTreeMap<usize, Arc<Pipe>>> = RwLock::new(BTreeMap::new());
 
 const MAX_QUEUE_SIZE: usize = 65536;

src/scheme/proc.rs

@@ -226,6 +226,7 @@ impl Handle {
 pub struct ProcScheme<const FULL: bool>;
 
 static NEXT_ID: AtomicUsize = AtomicUsize::new(1);
+// Using BTreeMap as hashbrown doesn't have a const constructor.
 static HANDLES: RwLock<BTreeMap<usize, Handle>> = RwLock::new(BTreeMap::new());
 
 #[derive(PartialEq)]

src/scheme/root.rs

@@ -1,10 +1,10 @@
 use alloc::{
     boxed::Box,
-    collections::BTreeMap,
     string::ToString,
     sync::Arc,
     vec::Vec,
 };
+use hashbrown::HashMap;
 use core::str;
 use core::sync::atomic::{AtomicUsize, Ordering};
 use spin::{Mutex, RwLock};
@@ -54,7 +54,7 @@ pub struct RootScheme {
     scheme_ns: SchemeNamespace,
     scheme_id: SchemeId,
     next_id: AtomicUsize,
-    handles: RwLock<BTreeMap<usize, Handle>>,
+    handles: RwLock<HashMap<usize, Handle>>,
 }
 
 impl RootScheme {
@@ -63,7 +63,7 @@ impl RootScheme {
             scheme_ns,
             scheme_id,
             next_id: AtomicUsize::new(0),
-            handles: RwLock::new(BTreeMap::new()),
+            handles: RwLock::new(HashMap::new()),
         }
     }
 }
@@ -298,7 +298,7 @@ impl KernelScheme for RootScheme {
             }
         }
     }
-    
+
     fn kfstat(&self, file: usize, buf: UserSliceWo) -> Result<()> {
         let handle = {
             let handles = self.handles.read();

src/scheme/serio.rs

@@ -22,6 +22,7 @@ struct Handle {
     flags: usize,
 }
 
+// Using BTreeMap as hashbrown doesn't have a const constructor.
 static HANDLES: RwLock<BTreeMap<usize, Handle>> = RwLock::new(BTreeMap::new());
 
 /// Add to the input queue

src/scheme/sys/mod.rs

@@ -36,6 +36,7 @@ type SysFn = fn() -> Result<Vec<u8>>;
 /// System information scheme
 pub struct SysScheme;
 static NEXT_ID: AtomicUsize = AtomicUsize::new(1);
+// Using BTreeMap as hashbrown doesn't have a const constructor.
 static HANDLES: RwLock<BTreeMap<usize, Handle>> = RwLock::new(BTreeMap::new());
 
 const FILES: &[(&'static str, SysFn)] = &[

src/scheme/time.rs

@@ -13,6 +13,7 @@ use crate::time;
 use super::{GlobalSchemes, KernelScheme, CallerCtx, OpenResult};
 
 static NEXT_ID: AtomicUsize = AtomicUsize::new(1);
+// Using BTreeMap as hashbrown doesn't have a const constructor.
 static HANDLES: RwLock<BTreeMap<usize, usize>> = RwLock::new(BTreeMap::new());
 
 pub struct TimeScheme;

src/scheme/user.rs

@@ -1,13 +1,12 @@
-use alloc::collections::btree_map::Entry;
 use alloc::sync::{Arc, Weak};
 use alloc::boxed::Box;
-use alloc::collections::BTreeMap;
 use alloc::vec::Vec;
 use syscall::{SKMSG_FRETURNFD, SKMSG_PROVIDE_MMAP, MAP_FIXED_NOREPLACE, MunmapFlags, SKMSG_FOBTAINFD, FobtainFdFlags, SendFdFlags};
 use core::mem::size_of;
 use core::num::NonZeroUsize;
 use core::sync::atomic::{AtomicBool, Ordering};
 use core::{mem, usize};
+use hashbrown::hash_map::{Entry, HashMap};
 use spin::{Mutex, RwLock};
 
 use crate::context::context::HardBlockedReason;
@@ -37,7 +36,7 @@ pub struct UserInner {
     next_id: Mutex<u64>,
     context: Weak<RwLock<Context>>,
     todo: WaitQueue<Packet>,
-    states: Mutex<BTreeMap<u64, State>>,
+    states: Mutex<HashMap<u64, State>>,
     unmounting: AtomicBool,
 }
 
@@ -71,7 +70,7 @@ impl UserInner {
             context,
             todo: WaitQueue::new(),
             unmounting: AtomicBool::new(false),
-            states: Mutex::new(BTreeMap::new()),
+            states: Mutex::new(HashMap::new()),
         }
     }