Use raw encoder for work-product index.

Author: cjgillot

compiler/rustc_incremental/src/persist/file_format.rs

@@ -122,6 +122,61 @@ where
     debug!("save: data written to disk successfully");
 }
 
+pub(crate) fn save_in_raw<F>(sess: &Session, path_buf: PathBuf, name: &str, encode: F)
+where
+    F: FnOnce(&mut raw::FileEncoder) -> raw::FileEncodeResult,
+{
+    debug!("save: storing data in {}", path_buf.display());
+
+    // Delete the old file, if any.
+    // Note: It's important that we actually delete the old file and not just
+    // truncate and overwrite it, since it might be a shared hard-link, the
+    // underlying data of which we don't want to modify.
+    //
+    // We have to ensure we have dropped the memory maps to this file
+    // before performing this removal.
+    match fs::remove_file(&path_buf) {
+        Ok(()) => {
+            debug!("save: remove old file");
+        }
+        Err(err) if err.kind() == io::ErrorKind::NotFound => (),
+        Err(err) => {
+            sess.err(&format!(
+                "unable to delete old {} at `{}`: {}",
+                name,
+                path_buf.display(),
+                err
+            ));
+            return;
+        }
+    }
+
+    let mut encoder = match raw::FileEncoder::new(&path_buf) {
+        Ok(encoder) => encoder,
+        Err(err) => {
+            sess.err(&format!("failed to create {} at `{}`: {}", name, path_buf.display(), err));
+            return;
+        }
+    };
+
+    if let Err(err) = write_file_header_raw(&mut encoder, sess.is_nightly_build()) {
+        sess.err(&format!("failed to write {} header to `{}`: {}", name, path_buf.display(), err));
+        return;
+    }
+
+    if let Err(err) = encode(&mut encoder) {
+        sess.err(&format!("failed to write {} to `{}`: {}", name, path_buf.display(), err));
+        return;
+    }
+
+    if let Err(err) = encoder.flush() {
+        sess.err(&format!("failed to flush {} to `{}`: {}", name, path_buf.display(), err));
+        return;
+    }
+
+    debug!("save: data written to disk successfully");
+}
+
 /// Reads the contents of a file with a file header as defined in this module.
 ///
 /// - Returns `Ok(Some(data, pos))` if the file existed and was generated by a

compiler/rustc_incremental/src/persist/load.rs

@@ -4,7 +4,7 @@ use rustc_data_structures::fx::FxHashMap;
 use rustc_data_structures::memmap::Mmap;
 use rustc_middle::dep_graph::{SerializedDepGraph, WorkProduct, WorkProductId};
 use rustc_middle::ty::OnDiskCache;
-use rustc_serialize::{opaque, raw, Decodable};
+use rustc_serialize::{raw, Decodable};
 use rustc_session::config::IncrementalStateAssertion;
 use rustc_session::Session;
 use std::path::Path;
@@ -155,7 +155,7 @@ pub fn load_dep_graph(sess: &Session) -> DepGraphFuture {
 
         if let LoadResult::Ok { data: (work_products_data, start_pos) } = load_result {
             // Decode the list of work_products
-            let mut work_product_decoder = opaque::Decoder::new(&work_products_data[..], start_pos);
+            let mut work_product_decoder = raw::Decoder::new(&work_products_data[..], start_pos);
             let work_products: Vec<SerializedWorkProduct> =
                 Decodable::decode(&mut work_product_decoder);
 

compiler/rustc_incremental/src/persist/save.rs

@@ -97,7 +97,7 @@ pub fn save_work_product_index(
     debug!("save_work_product_index()");
     dep_graph.assert_ignored();
     let path = work_products_path(sess);
-    file_format::save_in(sess, path, "work product index", |e| {
+    file_format::save_in_raw(sess, path, "work product index", |e| {
         encode_work_product_index(&new_work_products, e)
     });
 
@@ -128,8 +128,8 @@ pub fn save_work_product_index(
 
 fn encode_work_product_index(
     work_products: &FxHashMap<WorkProductId, WorkProduct>,
-    encoder: &mut opaque::FileEncoder,
-) -> opaque::FileEncodeResult {
+    encoder: &mut raw::FileEncoder,
+) -> raw::FileEncodeResult {
     let serialized_products: Vec<_> = work_products
         .iter()
         .map(|(id, work_product)| SerializedWorkProduct {