global: remove use of deprecated ZSTD_copyDCtx()

It was deprecated in 1.5.4. So we started seeing compiler warnings
post upgrade.

The C change was pretty straightforward. The Rust change not so much,
as we had to teach Rust to load the dictionary on the created dctx.
Since Rust didn't have this code before, it appears this was actually
optional as `ZSTD_copyDCtx()` had the same effect of copying any
referenced dictionary data?

Author: indygreg

c-ext/decompressor.c

@@ -1248,8 +1248,6 @@ decompress_from_framesources(ZstdDecompressor *decompressor,
             goto finally;
         }
 
-        ZSTD_copyDCtx(workerStates[i].dctx, decompressor->dctx);
-
         if (decompressor->dict) {
             zresult = ZSTD_DCtx_refDDict(workerStates[i].dctx,
                                          decompressor->dict->ddict);

docs/news.rst

@@ -86,6 +86,8 @@ Changes
 -------
 
 * Bundled zstd library upgraded from 1.5.2 to 1.5.4.
+* Use of the deprecated ``ZSTD_copyDCtx()`` was removed from the C and
+  Rust backends.
 
 0.19.0 (released 2022-10-29)
 ============================

rust-ext/src/decompressor.rs

@@ -410,7 +410,13 @@ impl ZstdDecompressor {
     ) -> PyResult<ZstdBufferWithSegmentsCollection> {
         self.setup_dctx(py, true)?;
 
-        multi_decompress_to_buffer(py, &self.dctx, frames, decompressed_sizes, threads)
+        multi_decompress_to_buffer(
+            py,
+            self.dict_data.as_ref(),
+            frames,
+            decompressed_sizes,
+            threads,
+        )
     }
 
     #[args(reader, read_size = "None", write_size = "None", skip_bytes = "None")]

rust-ext/src/decompressor_multi.rs

@@ -7,6 +7,7 @@
 use {
     crate::{
         buffers::{BufferSegment, ZstdBufferWithSegments, ZstdBufferWithSegmentsCollection},
+        compression_dict::ZstdCompressionDict,
         exceptions::ZstdError,
         zstd_safe::DCtx,
     },
@@ -27,7 +28,7 @@ struct DataSource<'a> {
 
 pub fn multi_decompress_to_buffer(
     py: Python,
-    dctx: &DCtx,
+    dict_data: Option<&Py<ZstdCompressionDict>>,
     frames: &PyAny,
     decompressed_sizes: Option<&PyAny>,
     threads: isize,
@@ -129,7 +130,7 @@ pub fn multi_decompress_to_buffer(
         ));
     }
 
-    decompress_from_datasources(py, dctx, sources, threads)
+    decompress_from_datasources(py, dict_data, sources, threads)
 }
 
 #[derive(Debug, PartialEq)]
@@ -148,7 +149,7 @@ struct WorkerResult {
 
 fn decompress_from_datasources(
     py: Python,
-    dctx: &DCtx,
+    dict_data: Option<&Py<ZstdCompressionDict>>,
     sources: Vec<DataSource>,
     thread_count: usize,
 ) -> PyResult<ZstdBufferWithSegmentsCollection> {
@@ -165,7 +166,12 @@ fn decompress_from_datasources(
     // to the C backend.
 
     for _ in 0..thread_count {
-        let dctx = dctx.try_clone().map_err(ZstdError::new_err)?;
+        let dctx = DCtx::new().map_err(ZstdError::new_err)?;
+
+        if let Some(dict_data) = dict_data {
+            dict_data.borrow_mut(py).load_into_dctx(&dctx)?;
+        }
+
         dctxs.push(dctx);
     }
 

rust-ext/src/zstd_safe.rs

@@ -357,17 +357,6 @@ impl<'a> DCtx<'a> {
         Ok(Self(dctx, PhantomData))
     }
 
-    /// Attempt to create a copy of this instance.
-    pub fn try_clone(&self) -> Result<Self, &'static str> {
-        let dctx = Self::new()?;
-
-        unsafe {
-            zstd_sys::ZSTD_copyDCtx(dctx.0, self.0);
-        }
-
-        Ok(dctx)
-    }
-
     pub fn dctx(&self) -> *mut zstd_sys::ZSTD_DCtx {
         self.0
     }