feat: add experimental shpool-vterm engine

This patch integrates the new shpool-vterm crate with
shpool as a replacement for shpool_vt100. For now, this
is opt in, and I expect it to be pretty broken in lots
of ways that we'll find out as people start trying it
out.

By default, we still use the old shpool_vt100 crate.

This is progress on #46

Author: ethanpailes

Cargo.lock

@@ -36,6 +36,7 @@ log = "0.4" # logging facade (not used directly, but required if we have tracing
 tracing = "0.1" # logging and performance monitoring facade
 rmp-serde = "1" # serialization for the control protocol
 shpool_vt100 = "0.1.3" # terminal emulation for the scrollback buffer
+shpool-vterm = "0.1.0" # alt terminal emulation for the scrollback buffer
 shell-words = "1" # parsing the -c/--cmd argument
 motd = { version = "0.2.2", default-features = false, features = [] } # getting the message-of-the-day
 termini = "1.0.0" # terminfo database

libshpool/Cargo.toml

@@ -245,6 +245,12 @@ pub struct Config {
     /// existing session.
     pub session_restore_mode: Option<SessionRestoreMode>,
 
+    /// Selects the virtual terminal to use for lines and screen
+    /// mode session restoration. By default, this is Vt100,
+    /// but you can opt into the experimental Vterm engine
+    /// if you want to try it out.
+    pub session_restore_engine: Option<SessionRestoreEngine>,
+
     /// The number of lines worth of output to keep in the output
     /// spool which is maintained along side a shell session.
     /// By default, 10000 lines.
@@ -312,6 +318,7 @@ impl Config {
             forward_env: self.forward_env.or(another.forward_env),
             initial_path: self.initial_path.or(another.initial_path),
             session_restore_mode: self.session_restore_mode.or(another.session_restore_mode),
+            session_restore_engine: self.session_restore_engine.or(another.session_restore_engine),
             output_spool_lines: self.output_spool_lines.or(another.output_spool_lines),
             vt100_output_spool_width: self
                 .vt100_output_spool_width
@@ -352,6 +359,16 @@ pub enum SessionRestoreMode {
     Lines(u16),
 }
 
+#[derive(Deserialize, Debug, Clone, Default)]
+#[serde(rename_all = "lowercase")]
+pub enum SessionRestoreEngine {
+    /// Use the shpool_vt100 crate for session restore.
+    #[default]
+    Vt100,
+    /// Use the shpool-vterm crate for session restore.
+    Vterm,
+}
+
 #[derive(Deserialize, Debug, Clone, Default)]
 #[serde(rename_all = "lowercase")]
 pub enum MotdDisplayMode {
@@ -413,6 +430,12 @@ mod test {
             binding = "Ctrl-q a"
             action = "detach"
             "#,
+            r#"
+            session_restore_engine = "vt100"
+            "#,
+            r#"
+            session_restore_engine = "vterm"
+            "#,
         ];
 
         for case in cases.into_iter() {

libshpool/src/config.rs

@@ -15,7 +15,7 @@
 use shpool_protocol::TtySize;
 use tracing::info;
 
-use crate::config::{self, SessionRestoreMode};
+use crate::config::{self, SessionRestoreMode, SessionRestoreEngine};
 
 // To prevent data getting dropped, we set this to be large, but we don't want
 // to use u16::MAX, since the vt100 crate eagerly fills in its rows, and doing
@@ -119,24 +119,59 @@ impl SessionSpool for Vt100Lines {
     }
 }
 
+/// A spool that restores the last screenful of content using shpool-vterm.
+pub struct Vterm {
+    term: shpool_vterm::Term,
+    mode: SessionRestoreMode,
+}
+
+impl SessionSpool for Vterm {
+    fn resize(&mut self, size: TtySize) {
+        self.term.resize(shpool_vterm::Size {
+            height: size.rows as usize,
+            width: size.cols as usize,
+        });
+    }
+
+    fn restore_buffer(&self) -> Vec<u8> {
+        match self.mode {
+            SessionRestoreMode::Simple => vec![],
+            SessionRestoreMode::Screen => self.term.contents(shpool_vterm::ContentRegion::Screen),
+            SessionRestoreMode::Lines(nlines) => self.term.contents(shpool_vterm::ContentRegion::BottomLines(nlines as usize)),
+        }
+    }
+
+    fn process(&mut self, bytes: &[u8]) {
+        self.term.process(bytes);
+    }
+}
+
 /// Creates a spool given a `mode`.
 pub fn new(
     config: config::Manager,
     size: &TtySize,
     scrollback_lines: usize,
 ) -> Box<dyn SessionSpool + 'static> {
+    let restore_engine = config.get().session_restore_engine.clone().unwrap_or_default();
     let mode = config.get().session_restore_mode.clone().unwrap_or_default();
     let vterm_width = config.vterm_width();
-    match mode {
-        SessionRestoreMode::Simple => Box::new(NullSpool),
-        SessionRestoreMode::Screen => Box::new(Vt100Screen {
+    match (mode, restore_engine) {
+        (SessionRestoreMode::Simple, _) => Box::new(NullSpool),
+        (SessionRestoreMode::Screen, SessionRestoreEngine::Vt100) => Box::new(Vt100Screen {
             parser: shpool_vt100::Parser::new(size.rows, vterm_width, scrollback_lines),
             config,
         }),
-        SessionRestoreMode::Lines(nlines) => Box::new(Vt100Lines {
+        (SessionRestoreMode::Lines(nlines), SessionRestoreEngine::Vt100) => Box::new(Vt100Lines {
             parser: shpool_vt100::Parser::new(size.rows, vterm_width, scrollback_lines),
             nlines,
             config,
         }),
+        (mode, SessionRestoreEngine::Vterm) => Box::new(Vterm {
+            term: shpool_vterm::Term::new(scrollback_lines, shpool_vterm::Size{
+                width: size.cols as usize,
+                height: size.rows as usize,
+            }),
+            mode,
+        }),
     }
 }

libshpool/src/session_restore.rs

@@ -0,0 +1,10 @@
+norc = true
+noecho = true
+shell = "/bin/bash"
+session_restore_mode = { lines = 5 }
+session_restore_engine = "vterm"
+prompt_prefix = ""
+
+[env]
+PS1 = "prompt> "
+TERM = ""

shpool/tests/data/vterm_lines.toml

@@ -0,0 +1,10 @@
+norc = true
+noecho = true
+shell = "/bin/bash"
+session_restore_mode = "screen"
+session_restore_engine = "vterm"
+prompt_prefix = ""
+
+[env]
+PS1 = "prompt> "
+TERM = ""

shpool/tests/data/vterm_screen.toml

@@ -0,0 +1,78 @@
+#![allow(clippy::literal_string_with_formatting_args)]
+
+use anyhow::Context;
+use ntest::timeout;
+
+mod support;
+
+use crate::support::{
+    daemon::DaemonArgs,
+};
+
+#[test]
+#[timeout(30000)]
+fn screen_restore() -> anyhow::Result<()> {
+    let mut daemon_proc = support::daemon::Proc::new("vterm_screen.toml", DaemonArgs::default())
+        .context("starting daemon proc")?;
+    let bidi_done_w = daemon_proc.events.take().unwrap().waiter(["daemon-bidi-stream-done"]);
+
+    {
+        let mut attach_proc =
+            daemon_proc.attach("sh1", Default::default()).context("starting attach proc")?;
+        let mut line_matcher = attach_proc.line_matcher()?;
+
+        attach_proc.run_cmd("echo foo")?;
+        line_matcher.scan_until_re("foo$")?;
+    }
+
+    // wait until the daemon has noticed that the connection
+    // has dropped before we attempt to open the connection again
+    daemon_proc.events = Some(bidi_done_w.wait_final_event("daemon-bidi-stream-done")?);
+
+    {
+        let mut attach_proc =
+            daemon_proc.attach("sh1", Default::default()).context("starting attach proc")?;
+        let mut line_matcher = attach_proc.line_matcher()?;
+
+        // the re-attach should redraw the screen for us, so we should
+        // get a line with "foo" as part of the re-drawn screen.
+        line_matcher.scan_until_re("foo$")?;
+
+        attach_proc.proc.kill()?;
+    }
+
+    Ok(())
+}
+
+#[test]
+#[timeout(30000)]
+fn lines_restore() -> anyhow::Result<()> {
+    let mut daemon_proc = support::daemon::Proc::new("vterm_lines.toml", DaemonArgs::default())
+        .context("starting daemon proc")?;
+    let bidi_done_w = daemon_proc.events.take().unwrap().waiter(["daemon-bidi-stream-done"]);
+
+    {
+        let mut attach_proc =
+            daemon_proc.attach("sh1", Default::default()).context("starting attach proc")?;
+        let mut line_matcher = attach_proc.line_matcher()?;
+
+        attach_proc.run_cmd("echo foo")?;
+        line_matcher.scan_until_re("foo$")?;
+    }
+
+    // wait until the daemon has noticed that the connection
+    // has dropped before we attempt to open the connection again
+    daemon_proc.events = Some(bidi_done_w.wait_final_event("daemon-bidi-stream-done")?);
+
+    {
+        let mut attach_proc =
+            daemon_proc.attach("sh1", Default::default()).context("starting attach proc")?;
+        let mut line_matcher = attach_proc.line_matcher()?;
+
+        // the re-attach should redraw the last 2 lines for us, so we should
+        // get a line with "foo" as part of the re-drawn screen.
+        line_matcher.scan_until_re("foo$")?;
+    }
+
+    Ok(())
+}