truce-loader

Plugin runtime + hot-reload infrastructure for truce.

Overview

Hot-reload mechanics for truce: dylib loading, ABI canary (including a sample_precision field that pins f32 vs f64), vtable probe, and the shells (HotShell<P, S>, StaticShell<P, L, S>) that bridge the user-facing leaf traits onto truce_core::Plugin for format wrappers. Used by every truce plugin, in two modes:

• Static (default). export_static! embeds the user's struct directly into the format wrapper at compile time. Zero runtime overhead, single dylib.
• Hot-reload (opt-in). export_plugin! exports the plugin across a #[no_mangle] C ABI in a separate dylib; the shell loads it via libloading, verifies ABI compatibility, and swaps the trait object on rebuild without restarting the DAW. Preserves audio continuity.

Plugin authors don't reach into this crate directly. They write a single impl PluginLogic (from truce-plugin) on their plugin struct -- one trait covering both DSP (reset, process, …) and GUI (layout, custom_editor, …) -- and truce::plugin! emits the right export_*! call based on the shell Cargo feature.

Key types and macros

• HotShell<P, S = f32> -- shell-side dylib loader and hot-swap manager, generic over the plugin's sample type.
• StaticShell<P, L, S = f32> -- shell-side wrapper that embeds the plugin at compile time, generic over the sample type.
• NativeLoader<S> -- the libloading-backed dylib loader that holds Box<dyn PluginLogicCore<S>> and the canary + vtable-probe machinery.
• AbiCanary -- ABI fingerprint compared between shell and dylib before loading. Includes sample_precision: u8 so a prelude64 logic dylib loaded by an f32 shell (or vice versa) fails the canary check rather than binding to a wrong-layout vtable.
• export_static! -- emits the __HotShellWrapper for static mode.
• export_plugin! -- emits the #[no_mangle] C ABI symbols for shell mode (truce_create, truce_abi_canary, truce_vtable_probe). Each one carries the plugin's chosen precision (via the prelude's Sample alias).

Features

Usage

Enable the dynamic shell (hot-reload) during development:

[dependencies]
truce = { git = "https://github.com/truce-audio/truce", tag = "vX.Y.Z", features = ["shell"] }

(Replace vX.Y.Z with the latest release tag.)

Part of truce.