make stdin async

crsn/src/runtime/fault.rs

@@ -86,6 +86,9 @@ pub enum Fault {
 
     #[error("Root routine returned or yielded a value")]
     RootReturned,
+
+    #[error("System IO error: {0}")]
+    IOError(#[from] std::io::Error),
 }
 
 #[derive(Error, Debug)]

crsn/src/runtime/run_thread.rs

@@ -153,7 +153,9 @@ impl RunThread {
                     }
                 }
                 Err(Fault::Blocked) => {
-                    // Do not advance, the last instruction will be re-tried
+                    trace!("Thread reports being blocked!");
+                    self.state.cr.frame.pc = orig_pc; // Retry
+                    self.state.cr.cr_state = CoroutineState::Ready;
                     want_switch = true;
                 }
                 Err(e) => {
@@ -191,18 +193,20 @@ impl RunThread {
 
                     let mut candidate = None;
                     let mut closest_due = None;
-                    for _ in 0..self.state.parked.len() {
+                    'findbest: for _ in 0..self.state.parked.len() {
                         if let Some(mut rt) = self.state.parked.pop_front() {
                             match rt.cr_state {
                                 CoroutineState::Ready => {
+                                    trace!("Found READY thread to run next");
                                     candidate = Some(rt);
-                                    break;
+                                    break 'findbest;
                                 }
                                 CoroutineState::Sleep { due } => {
                                     if due <= now {
+                                        trace!("Found DUE sleeping thread to run next");
                                         rt.cr_state = CoroutineState::Ready;
                                         candidate = Some(rt);
-                                        break;
+                                        break 'findbest;
                                     } else {
                                         match closest_due {
                                             Some(d) => {
@@ -234,10 +238,15 @@ impl RunThread {
                         self.state.start_task_switching();
 
                     } else if let Some(due) = closest_due {
+                        if self.state.cr.cr_state == CoroutineState::Ready {
+                            trace!("No candidate found to run, retry same thread.");
+                            // Let it run another quantum, maybe it was just blocked
+                            continue 'run;
+                        }
+
                         let time = due.saturating_duration_since(now);
                         trace!("No thread to switch to, sleep {:?}", time);
                         thread::sleep(time);
-
                         continue 'next;
                     } else {
                         // Nothing to run?

crsn_stdio/src/lib.rs

@@ -14,6 +14,7 @@ use std::io;
 use crsn::asm::instr::cond::Flag;
 use std::fmt;
 use crsn::asm::data::Wr;
+use std::time::Instant;
 
 mod console {
     use std::{io};
@@ -21,13 +22,29 @@ mod console {
 
     use std::ffi::c_void;
     use std::mem::{self, MaybeUninit};
+    use crsn::runtime::fault::Fault;
+    use std::time::{Duration, Instant};
+
+    struct ReadCharState {
+        bytes: [u8; 4],
+        cursor: usize,
+        len: usize,
+        last_timeout : u8,
+    }
+
+    static mut READ_CHAR_STATE: ReadCharState = ReadCharState {
+        bytes: [0; 4],
+        cursor: 0,
+        len: 0,
+        last_timeout : 0,
+    };
 
-    fn setup_fd(fd: RawFd) -> io::Result<libc::termios> {
+    fn setup_fd(fd: RawFd) -> Result<libc::termios, Fault> {
         use libc::*;
 
         let mut tio = MaybeUninit::uninit();
         if 0 != unsafe { tcgetattr(fd, tio.as_mut_ptr()) } {
-            return Err(io::Error::last_os_error());
+            return Err(Fault::IOError(io::Error::last_os_error()));
         }
         let mut tio = unsafe { MaybeUninit::assume_init(tio) };
         let old_tio : termios = unsafe { mem::transmute_copy(&tio) };
@@ -39,36 +56,76 @@ mod console {
         tio.c_cc[VMIN] = 1;
         tio.c_cc[VTIME] = 0;
         if 0 != unsafe { tcsetattr(fd, TCSANOW, &tio) } {
-            return Err(io::Error::last_os_error());
+            return Err(Fault::IOError(io::Error::last_os_error()));
         }
 
         Ok(old_tio)
     }
 
-    pub fn init_io() -> io::Result<libc::termios> {
+    pub fn init_io() -> Result<libc::termios, Fault> {
         setup_fd(libc::STDIN_FILENO)
     }
 
-    pub fn read_byte() -> io::Result<u8> {
+    pub fn read_byte(deadline : Option<Instant>) -> Result<u8, Fault> {
+        // Set TIO timeout
+        let state = unsafe { &mut READ_CHAR_STATE };
+
+        if (state.last_timeout == 0) && deadline.is_none() {
+            // Keep it like that
+        }  else {
+            let vtime = if let Some(dl) = deadline {
+                let timeout = dl.saturating_duration_since(Instant::now());
+                ((timeout.as_secs_f32() * 10.0).round() as u32).min(255).max(1) as u8
+            } else {
+                0
+            };
+
+            if state.last_timeout != vtime {
+                // vtime changes
+                state.last_timeout = vtime;
+
+                let mut tio = MaybeUninit::uninit();
+                if 0 != unsafe { libc::tcgetattr(libc::STDIN_FILENO, tio.as_mut_ptr()) } {
+                    return Err(Fault::IOError(io::Error::last_os_error()));
+                }
+                let mut tio = unsafe { MaybeUninit::assume_init(tio) };
+
+                if vtime > 0 {
+                    tio.c_cc[libc::VTIME] = vtime; /* unit = 0.1 */
+                    tio.c_cc[libc::VMIN] = 0;
+                } else {
+                    tio.c_cc[libc::VTIME] = 0; // no counting
+                    tio.c_cc[libc::VMIN] = 1; // want at least one character
+                }
+
+                unsafe { libc::tcsetattr(libc::STDIN_FILENO, libc::TCSANOW, &tio) };
+            }
+        }
+
         let mut buf = 0u8;
         let len = unsafe { libc::read(libc::STDIN_FILENO, &mut buf as *mut u8 as *mut c_void, 1) };
+
+        if len == 0 && state.last_timeout != 0 {
+            return Err(Fault::IOError(io::Error::new(std::io::ErrorKind::TimedOut, "")));
+        }
+
         if len <= 0 {
-            Err(io::Error::last_os_error())
+            Err(Fault::IOError(io::Error::last_os_error()))
         } else {
             Ok(buf as u8)
         }
     }
 
-    pub fn write_byte(b : u8) -> io::Result<()> {
+    pub fn write_byte(b : u8) -> Result<(), Fault> {
         let len = unsafe { libc::write(libc::STDOUT_FILENO, &b as *const u8 as *const c_void, 1) };
         if len <= 0 {
-            Err(io::Error::last_os_error())
+            Err(Fault::IOError(io::Error::last_os_error()))
         } else {
             Ok(())
         }
     }
 
-    pub fn write_char(c : char) -> io::Result<()> {
+    pub fn write_char(c : char) -> Result<(), Fault> {
         let mut buf = [0u8; 4];
         for b in c.encode_utf8(&mut buf).as_bytes() {
             write_byte(*b)?;
@@ -76,30 +133,43 @@ mod console {
         Ok(())
     }
 
-    pub fn read_char() -> io::Result<char> {
-        let first = read_byte()?;
+    pub fn read_char(deadline : Option<Instant>) -> Result<char, Fault> {
+        let state = unsafe { &mut READ_CHAR_STATE };
 
-        if first & 0x80 == 0 {
-            return Ok(first as char);
-        }
+        if state.cursor == 0 {
+            let first = read_byte(deadline)?;
 
-        let mut bytes = [first, 0, 0, 0];
+            if first & 0x80 == 0 {
+                return Ok(first as char);
+            }
 
-        let remain = if first & 0b1110_0000 == 0b1100_0000 {
-            1
-        } else if first & 0b1111_0000 == 0b1110_0000 {
-            2
-        } else /*if first & 0b1111_1000 == 0b1111_0000*/ {
-            3
-        };
+            state.bytes[0] = first;
+            state.cursor = 1;
+            state.len = if first & 0b1110_0000 == 0b1100_0000 {
+                2
+            } else if first & 0b1111_0000 == 0b1110_0000 {
+                3
+            } else /*if first & 0b1111_1000 == 0b1111_0000*/ {
+                4
+            };
+        }
 
-        for n in 1..=remain {
-            bytes[n] = read_byte()?;
+        let len = state.len;
+
+        while state.cursor < len {
+            let b = read_byte(deadline)?;
+            state.bytes[state.cursor] = b;
+            state.cursor += 1;
         }
 
-        std::str::from_utf8(&bytes[..=remain])
+        let rv = std::str::from_utf8(&state.bytes[..=len])
             .map(|s| s.chars().nth(0).unwrap())
-            .map_err(|e| io::Error::new(io::ErrorKind::InvalidData, e))
+            .map_err(|e| Fault::IOError(io::Error::new(io::ErrorKind::InvalidData, e)));
+
+        state.cursor = 0;
+        state.len = 0;
+
+        rv
     }
 }
 
@@ -183,35 +253,47 @@ impl CrsnExtension for StdioOps {
     fn read_obj(&self, state: &mut RunState, handle: Value)
                 -> Result<Option<Value>, Fault>
     {
+        let deadline = state.cr_deadline;
+
         if handle == self.hdl_stdin {
-            match console::read_char() {
+            match console::read_char(deadline) {
                 Ok(c) => {
                     return Ok(Some(c as Value));
                 }
-                Err(e) => {
+                Err(Fault::IOError(e)) => {
+                    if e.kind() == io::ErrorKind::TimedOut {
+                        return Err(Fault::Blocked);
+                    }
+
                     state.set_flag(Flag::Invalid, true);
                     if e.kind() != io::ErrorKind::InvalidData {
                         state.set_flag(Flag::Eof, true);
                     }
                     return Ok(Some(0));
                 }
+                Err(other) => {
+                    return Err(other);
+                }
             }
-        }
-
-        if handle == self.hdl_stdin_raw {
-            match console::read_byte() {
+        } else if handle == self.hdl_stdin_raw {
+            match console::read_byte(deadline) {
                 Ok(b) => {
                     return Ok(Some(b as Value));
                 }
-                Err(_e) => {
+                Err(Fault::IOError(e)) => {
+                    if e.kind() == io::ErrorKind::TimedOut {
+                        return Err(Fault::Blocked);
+                    }
+
                     state.set_flag(Flag::Invalid, true);
                     state.set_flag(Flag::Eof, true);
                     return Ok(Some(0));
                 }
+                Err(other) => {
+                    return Err(other);
+                }
             }
-        }
-
-        if handle == self.hdl_stdout || handle == self.hdl_stdout_raw {
+        } else if handle == self.hdl_stdout || handle == self.hdl_stdout_raw {
             state.set_flag(Flag::Invalid, true);
             return Ok(Some(0));
         }
@@ -254,13 +336,15 @@ impl CrsnExtension for StdioOps {
     fn read_obj_all(&self, state: &mut RunState, whandle: Wr, rhandle: Value)
                     -> Result<Option<()>, Fault>
     {
+        // XXX This is blocking, there is no sensible way to split it up.
+
         if rhandle == self.hdl_stdin {
             loop {
-                match console::read_char() {
+                match console::read_char(None) {
                     Ok(c) => {
                         state.write(whandle, c as Value)?;
                     }
-                    Err(e) => {
+                    Err(Fault::IOError(e)) => {
                         if e.kind() != io::ErrorKind::InvalidData {
                             state.set_flag(Flag::Eof, true);
                         } else {
@@ -268,17 +352,20 @@ impl CrsnExtension for StdioOps {
                         }
                         return Ok(Some(()));
                     }
+                    Err(other) => {
+                        return Err(other);
+                    }
                 }
             }
         }
 
         if rhandle == self.hdl_stdin_raw {
             loop {
-                match console::read_byte() {
+                match console::read_byte(None) {
                     Ok(c) => {
                         state.write(whandle, c as Value)?;
                     }
-                    Err(e) => {
+                    Err(Fault::IOError(e)) => {
                         if e.kind() != io::ErrorKind::InvalidData {
                             state.set_flag(Flag::Eof, true);
                         } else {
@@ -286,6 +373,9 @@ impl CrsnExtension for StdioOps {
                         }
                         return Ok(Some(()));
                     }
+                    Err(other) => {
+                        return Err(other);
+                    }
                 }
             }
         }

examples/coroutines4-io.csn

@@ -0,0 +1,17 @@
+(
+    ; This demo shows that stdin is nearly non-blocking
+
+    (spawn _ ReadAndEcho)
+
+    (:a)
+    (mslp 2500)
+    (lds @cout "Tick\n")
+    (j :a)
+
+    (proc ReadAndEcho
+        (:a)
+        (ld @cout '?')
+        (ld @cout @cin)
+        (j :a)
+    )
+)