Add boilerplate for an actual JACK implementation

Cargo.lock

@@ -1772,6 +1772,32 @@ version = "1.0.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "112c678d4050afce233f4f2852bb2eb519230b3cf12f33585275537d7e41578d"
 
+[[package]]
+name = "jack"
+version = "0.10.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ce722655a29b13bb98ec7e8ba9dc65d670b9b37c7b1c09775c7f7516811c5a36"
+dependencies = [
+ "bitflags",
+ "jack-sys",
+ "lazy_static",
+ "libc",
+ "log",
+]
+
+[[package]]
+name = "jack-sys"
+version = "0.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e9d70559ff166d148ccb750ddd77702af760718f3a752c731add168c22c16a9f"
+dependencies = [
+ "bitflags",
+ "lazy_static",
+ "libc",
+ "libloading",
+ "pkg-config",
+]
+
 [[package]]
 name = "jpeg-decoder"
 version = "0.1.22"
@@ -2106,6 +2132,7 @@ dependencies = [
  "clap",
  "clap-sys",
  "crossbeam",
+ "jack",
  "lazy_static",
  "libc",
  "log",

Cargo.toml

@@ -47,7 +47,7 @@ assert_process_allocs = ["dep:assert_no_alloc"]
 # Enables an export target for standalone binaries through the
 # `nih_export_standalone()` function. Disabled by default, as this requires
 # building additional dependencies for audio and MIDI handling.
-standalone = ["dep:anyhow", "dep:baseview", "dep:clap"]
+standalone = ["dep:anyhow", "dep:baseview", "dep:clap", "dep:jack"]
 # Enables the `nih_export_vst3!()` macro. Enabled by default. This feature
 # exists mostly for GPL-compliance reasons, since even if you don't use the VST3
 # wrapper you might otherwise still include a couple (unused) symbols from the
@@ -89,6 +89,7 @@ anyhow = { version = "1.0", optional = true }
 baseview = { git = "https://github.com/robbert-vdh/baseview.git", branch = "feature/resize", features = ["opengl"], optional = true }
 # All the claps!
 clap = { version = "3.2", features = ["derive"], optional = true }
+jack = { version = "0.10.0", optional = true }
 
 # Used for the `vst3` feature
 vst3-sys = { git = "https://github.com/robbert-vdh/vst3-sys.git", branch = "fix/note-off-event", optional = true }

src/wrapper/standalone.rs

@@ -70,14 +70,14 @@ pub fn nih_export_standalone_with_args<P: Plugin, Args: IntoIterator<Item = Stri
     .unwrap_or_else(|err| err.exit());
 
     match config.backend {
-        config::BackendType::Auto => match backend::Jack::new(config.clone()) {
+        config::BackendType::Auto => match backend::Jack::new(P::NAME, config.clone()) {
             Ok(backend) => run_wrapper::<P, _>(backend, config),
             Err(_) => {
                 nih_log!("Could not initialize JACK, falling back to the dummy audio backend");
                 run_wrapper::<P, _>(backend::Dummy::new(config.clone()), config)
             }
         },
-        config::BackendType::Jack => match backend::Jack::new(config.clone()) {
+        config::BackendType::Jack => match backend::Jack::new(P::NAME, config.clone()) {
             Ok(backend) => run_wrapper::<P, _>(backend, config),
             Err(err) => {
                 nih_error!("Could not initialize the JACK backend: {:#}", err);

src/wrapper/standalone/backend.rs

@@ -1,4 +1,4 @@
-use anyhow::Result;
+use anyhow::{Context, Result};
 use std::time::{Duration, Instant};
 
 use crate::buffer::Buffer;
@@ -19,6 +19,7 @@ pub trait Backend: 'static + Send + Sync {
 /// Uses JACK audio and MIDI.
 pub struct Jack {
     config: WrapperConfig,
+    client: jack::Client,
 }
 
 /// This backend doesn't input or output any audio or MIDI. It only exists so the standalone
@@ -30,6 +31,7 @@ pub struct Dummy {
 
 impl Backend for Jack {
     fn run(&mut self, cb: impl FnMut(&mut Buffer) -> bool) {
+        // TODO: Create an async client and do The Thing (tm)
         todo!()
     }
 }
@@ -75,10 +77,18 @@ impl Backend for Dummy {
 
 impl Jack {
     /// Initialize the JACK backend. Returns an error if this failed for whatever reason.
-    pub fn new(config: WrapperConfig) -> Result<Self> {
+    pub fn new(name: &str, config: WrapperConfig) -> Result<Self> {
-        // TODO: Actually implement the JACK backend
+        let (client, status) = jack::Client::new(name, jack::ClientOptions::NO_START_SERVER)
-        anyhow::bail!("Not yet implemented")
+            .context("Error while initializing the JACK client")?;
-        // Ok(Self { config })
+        if !status.is_empty() {
+            anyhow::bail!("The JACK server returned an error: {status:?}");
+        }
+
+        // TODO: Register ports
+        // TODO: Connect output
+        // TODO: Command line argument to connect the inputs?
+
+        Ok(Self { config, client })
     }
 }
 

src/wrapper/standalone/config.rs

@@ -18,9 +18,13 @@ pub struct WrapperConfig {
     #[clap(value_parser, short = 'o', long, default_value = "2")]
     pub output_channels: u32,
     /// The audio backend's sample rate.
+    ///
+    /// This setting is ignored when using the JACK backend.
     #[clap(value_parser, short = 'r', long, default_value = "44100")]
     pub sample_rate: f32,
     /// The audio backend's period size.
+    ///
+    /// This setting is ignored when using the JACK backend.
     #[clap(value_parser, short = 'p', long, default_value = "512")]
     pub period_size: u32,