Add optional Zstandard compression for state

This can be particularly useful when using the persistent fields feature
to store JSON or other large textual documents.

.github/workflows/docs.yml

@@ -51,7 +51,7 @@ jobs:
           # conflicting iced features. We also don't want to use `--workspace`
           # here because that would also document our plugins and binary crates.
           args: >-
-            --features docs,simd,standalone --no-deps
+            --features docs,simd,standalone,zstd --no-deps
             -p nih_plug
             -p nih_plug_derive
             -p nih_plug_egui

.github/workflows/test.yml

@@ -60,7 +60,7 @@ jobs:
           command: build
           # Don't use --all-features as that will enable a whole bunch of
           # conflicting iced features
-          args: --workspace --features "simd,standalone"
+          args: --workspace --features "simd,standalone,zstd"
       - name: Run the tests
         uses: actions-rs/cargo@v1
         with:

Cargo.lock

@@ -449,6 +449,9 @@ name = "cc"
 version = "1.0.73"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "2fff2a6927b3bb87f9595d67196a70493f627687a71d87a0d692242c33f58c11"
+dependencies = [
+ "jobserver",
+]
 
 [[package]]
 name = "cfg-if"
@@ -1992,6 +1995,15 @@ version = "0.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "8eaf4bc02d17cbdd7ff4c7438cafcdf7fb9a4613313ad11b4f8fefe7d3fa0130"
 
+[[package]]
+name = "jobserver"
+version = "0.1.24"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "af25a77299a7f711a01975c35a6a424eb6862092cc2d6c72c4ed6cbc56dfc1fa"
+dependencies = [
+ "libc",
+]
+
 [[package]]
 name = "jpeg-decoder"
 version = "0.1.22"
@@ -2397,6 +2409,7 @@ dependencies = [
  "widestring",
  "win_dbg_logger",
  "windows",
+ "zstd",
 ]
 
 [[package]]
@@ -4686,3 +4699,32 @@ version = "0.1.0"
 dependencies = [
  "nih_plug_xtask",
 ]
+
+[[package]]
+name = "zstd"
+version = "0.11.2+zstd.1.5.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "20cc960326ece64f010d2d2107537f26dc589a6573a316bd5b1dba685fa5fde4"
+dependencies = [
+ "zstd-safe",
+]
+
+[[package]]
+name = "zstd-safe"
+version = "5.0.2+zstd.1.5.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1d2a5585e04f9eea4b2a3d1eca508c4dee9592a89ef6f450c11719da0726f4db"
+dependencies = [
+ "libc",
+ "zstd-sys",
+]
+
+[[package]]
+name = "zstd-sys"
+version = "2.0.1+zstd.1.5.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9fd07cbbc53846d9145dbffdf6dd09a7a0aa52be46741825f5c97bdd4f73f12b"
+dependencies = [
+ "cc",
+ "libc",
+]

Cargo.toml

@@ -49,7 +49,7 @@ 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", "dep:jack"]
+standalone = ["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
@@ -58,12 +58,19 @@ vst3 = ["dep:vst3-sys"]
 # Add adapters to the Buffer object for reading the channel data to and from
 # `std::simd` vectors. Requires a nightly compiler.
 simd = []
+# Compress plugin state using the Zstandard algorithm. Loading uncompressed
+# state is still supported so existing state will still load after enabling this
+# feature for a plugin, but it can not be disabled again without losing state
+# compatibility.
+zstd = ["dep:zstd"]
+
 # Only relevant when generating docs, adds the `doc_auto_cfg` nightly feature
 docs = []
 
 [dependencies]
 nih_plug_derive = { path = "nih_plug_derive" }
 
+anyhow = "1.0"
 atomic_float = "0.1"
 atomic_refcell = "0.1"
 backtrace = "0.3.65"
@@ -85,7 +92,6 @@ widestring = "1.0.0-beta.1"
 assert_no_alloc = { version = "1.1", optional = true }
 
 # Used for the `standalone` feature
-anyhow = { version = "1.0", optional = true }
 # NOTE: OpenGL support is not needed here, but rust-analyzer gets confused when
 #       some crates do use it and others don't
 baseview = { git = "https://github.com/robbert-vdh/baseview.git", branch = "feature/resize", features = ["opengl"], optional = true }
@@ -97,6 +103,9 @@ jack = { git = "https://github.com/robbert-vdh/rust-jack.git", branch = "feature
 # Used for the `vst3` feature
 vst3-sys = { git = "https://github.com/robbert-vdh/vst3-sys.git", branch = "fix/note-off-event", optional = true }
 
+# Used for the `zstd` feature
+zstd = { version = "0.11.2", optional = true }
+
 [target.'cfg(all(target_family = "unix", not(target_os = "macos")))'.dependencies]
 libc = "0.2.124"
 

README.md

@@ -116,6 +116,8 @@ Scroll down for more information on the plugin framework.
   enabled by setting the `Plugin::SAMPLE_ACCURATE_AUTOMATION` constant to
   `true`.
 - Support for CLAP's polyphonic modulation on a per-parameter basis.
+- Optional support for compressing the human readable JSON state files using
+  [Zstandard](https://en.wikipedia.org/wiki/Zstd).
 - Comes with adapters for popular Rust GUI frameworks as well as some basic
   widgets for them that integrate with NIH-plug's parameter system. Currently
   there's support for [egui](nih_plug_egui), [iced](nih_plug_iced) and

plugins/examples/gain/Cargo.toml

@@ -9,6 +9,6 @@ license = "ISC"
 crate-type = ["cdylib"]
 
 [dependencies]
-nih_plug = { path = "../../../", features = ["assert_process_allocs"] }
+nih_plug = { path = "../../../", features = ["assert_process_allocs", "zstd"] }
 
 parking_lot = "0.12"

src/wrapper/clap/wrapper.rs

@@ -3139,7 +3139,7 @@ impl<P: ClapPlugin> Wrapper<P> {
                 true
             }
             Err(err) => {
-                nih_debug_assert_failure!("Could not save state: {}", err);
+                nih_debug_assert_failure!("Could not save state: {:#}", err);
                 false
             }
         }

src/wrapper/state.rs

@@ -1,6 +1,7 @@
 //! Utilities for saving a [crate::plugin::Plugin]'s state. The actual state object is also exposed
 //! to plugins through the [`GuiContext`][crate::prelude::GuiContext].
 
+use anyhow::{Context, Result};
 use serde::{Deserialize, Serialize};
 use std::collections::{BTreeMap, HashMap};
 use std::sync::Arc;
@@ -115,13 +116,24 @@ pub(crate) unsafe fn serialize_object<'a>(
 }
 
 /// Serialize a plugin's state to a vector containing JSON data. This can (and should) be shared
-/// across plugin formats.
+/// across plugin formats. If the `zstd` feature is enabled, then the state will be compressed using
+/// Zstandard.
 pub(crate) unsafe fn serialize_json<'a>(
     plugin_params: Arc<dyn Params>,
     params_iter: impl IntoIterator<Item = (&'a String, ParamPtr)>,
-) -> serde_json::Result<Vec<u8>> {
+) -> Result<Vec<u8>> {
     let plugin_state = serialize_object(plugin_params, params_iter);
-    serde_json::to_vec(&plugin_state)
+    let json = serde_json::to_vec(&plugin_state).context("Could not format as JSON")?;
+
+    #[cfg(feature = "zstd")]
+    {
+        zstd::encode_all(json.as_slice(), zstd::DEFAULT_COMPRESSION_LEVEL)
+            .context("Could not compress state")
+    }
+    #[cfg(not(feature = "zstd"))]
+    {
+        Ok(json)
+    }
 }
 
 /// Deserialize a plugin's state from a [`PluginState`] object. This is used to allow the plugin to
@@ -191,8 +203,9 @@ pub(crate) unsafe fn deserialize_object(
     true
 }
 
-/// Deserialize a plugin's state from a vector containing JSON data. This can (and should) be shared
+/// Deserialize a plugin's state from a vector containing (compressed) JSON data. This can (and
-/// across plugin formats. Returns `false` and logs an error if the state could not be deserialized.
+/// should) be shared across plugin formats. Returns `false` and logs an error if the state could
+/// not be deserialized. If the `zstd` feature is enabled, then this can
 ///
 /// Make sure to reinitialize plugin after deserializing the state so it can react to the new
 /// parameter values. The smoothers have already been reset by this function.
@@ -202,6 +215,38 @@ pub(crate) unsafe fn deserialize_json(
     params_getter: impl Fn(&str) -> Option<ParamPtr>,
     current_buffer_config: Option<&BufferConfig>,
 ) -> bool {
+    #[cfg(feature = "zstd")]
+    let state: PluginState = match zstd::decode_all(state) {
+        Ok(decompressed) => match serde_json::from_slice(decompressed.as_slice()) {
+            Ok(s) => {
+                nih_log!("Deserialized compressed");
+                s
+            }
+            Err(err) => {
+                nih_debug_assert_failure!("Error while deserializing state: {}", err);
+                return false;
+            }
+        },
+        // Uncompressed state files can still be loaded after enabling this feature to prevent
+        // breaking existing plugin instances
+        Err(zstd_err) => match serde_json::from_slice(state) {
+            Ok(s) => {
+                nih_log!("Deserialized uncompressed");
+                s
+            }
+            Err(json_err) => {
+                nih_debug_assert_failure!(
+                    "Error while deserializing state as either compressed or uncompressed state: \
+                     {}, {}",
+                    zstd_err,
+                    json_err
+                );
+                return false;
+            }
+        },
+    };
+
+    #[cfg(not(feature = "zstd"))]
     let state: PluginState = match serde_json::from_slice(state) {
         Ok(s) => s,
         Err(err) => {

src/wrapper/vst3/wrapper.rs

@@ -555,7 +555,7 @@ impl<P: Vst3Plugin> IComponent for Wrapper<P> {
                 kResultOk
             }
             Err(err) => {
-                nih_debug_assert_failure!("Could not save state: {}", err);
+                nih_debug_assert_failure!("Could not save state: {:#}", err);
                 kResultFalse
             }
         }