Rename GetFileDigest to StoreFileByDigest

Add a comment explaining why it exists.

src/rust/engine/fs/fs_util/src/main.rs

@@ -7,7 +7,7 @@ extern crate protobuf;
 
 use boxfuture::{Boxable, BoxFuture};
 use clap::{App, Arg, SubCommand};
-use fs::{Fingerprint, GetFileDigest, ResettablePool, Snapshot, Store, VFS};
+use fs::{Fingerprint, ResettablePool, Snapshot, Store, StoreFileByDigest, VFS};
 use futures::future::{self, Future, join_all};
 use protobuf::Message;
 use std::error::Error;
@@ -196,7 +196,7 @@ fn execute(top_match: clap::ArgMatches) -> Result<(), ExitError> {
               let digest = FileSaver {
                 store: store,
                 posix_fs: Arc::new(posix_fs),
-              }.digest(&f)
+              }.store_by_digest(&f)
                 .wait()
                 .unwrap();
               Ok(println!("{} {}", digest.0, digest.1))
@@ -327,8 +327,8 @@ struct FileSaver {
   posix_fs: Arc<fs::PosixFS>,
 }
 
-impl GetFileDigest<String> for FileSaver {
-  fn digest(&self, file: &fs::File) -> BoxFuture<fs::Digest, String> {
+impl StoreFileByDigest<String> for FileSaver {
+  fn store_by_digest(&self, file: &fs::File) -> BoxFuture<fs::Digest, String> {
     let file_copy = file.clone();
     let store = self.store.clone();
     self

src/rust/engine/fs/src/lib.rs

@@ -4,7 +4,7 @@
 mod hash;
 pub use hash::Fingerprint;
 mod snapshot;
-pub use snapshot::{GetFileDigest, Snapshot};
+pub use snapshot::{Snapshot, StoreFileByDigest};
 mod store;
 pub use store::{Digest, Store};
 mod pool;

src/rust/engine/fs/src/snapshot.rs

@@ -21,17 +21,21 @@ pub struct Snapshot {
   pub path_stats: Vec<PathStat>,
 }
 
-pub trait GetFileDigest<Error> {
-  fn digest(&self, file: &File) -> BoxFuture<Digest, Error>;
+// StoreFileByDigest allows a File to be saved to an underlying Store, in such a way that it can be
+// looked up by the Digest produced by the store_by_digest method.
+// It is a separate trait so that caching implementations can be written which wrap the Store (used
+// to store the bytes) and VFS (used to read the files off disk if needed).
+pub trait StoreFileByDigest<Error> {
+  fn store_by_digest(&self, file: &File) -> BoxFuture<Digest, Error>;
 }
 
 impl Snapshot {
   pub fn from_path_stats<
-    GFD: GetFileDigest<Error> + Sized + Clone,
+    SFBD: StoreFileByDigest<Error> + Sized + Clone,
     Error: fmt::Debug + 'static + Send,
   >(
     store: Arc<Store>,
-    file_digester: GFD,
+    file_digester: SFBD,
     path_stats: Vec<PathStat>,
   ) -> BoxFuture<Snapshot, String> {
     let mut sorted_path_stats = path_stats.clone();
@@ -42,11 +46,11 @@ impl Snapshot {
   }
 
   fn ingest_directory_from_sorted_path_stats<
-    GFD: GetFileDigest<Error> + Sized + Clone,
+    SFBD: StoreFileByDigest<Error> + Sized + Clone,
     Error: fmt::Debug + 'static + Send,
   >(
     store: Arc<Store>,
-    file_digester: GFD,
+    file_digester: SFBD,
     path_stats: Vec<PathStat>,
   ) -> BoxFuture<Digest, String> {
     let mut file_futures: Vec<BoxFuture<bazel_protos::remote_execution::FileNode, String>> =
@@ -73,7 +77,7 @@ impl Snapshot {
             file_futures.push(
               file_digester
                 .clone()
-                .digest(&stat)
+                .store_by_digest(&stat)
                 .map_err(|e| format!("{:?}", e))
                 .and_then(move |digest| {
                   let mut file_node = bazel_protos::remote_execution::FileNode::new();
@@ -275,8 +279,8 @@ mod tests {
   use tempdir::TempDir;
   use self::testutil::make_file;
 
-  use super::super::{Digest, File, FileContent, Fingerprint, GetFileDigest, PathGlobs, PathStat,
-                     PosixFS, ResettablePool, Snapshot, Store, VFS};
+  use super::super::{Digest, File, FileContent, Fingerprint, PathGlobs, PathStat, PosixFS,
+                     ResettablePool, Snapshot, Store, StoreFileByDigest, VFS};
 
   use std;
   use std::error::Error;
@@ -452,8 +456,8 @@ mod tests {
   #[derive(Clone)]
   struct FileSaver(Arc<Store>, Arc<PosixFS>);
 
-  impl GetFileDigest<String> for FileSaver {
-    fn digest(&self, file: &File) -> BoxFuture<Digest, String> {
+  impl StoreFileByDigest<String> for FileSaver {
+    fn store_by_digest(&self, file: &File) -> BoxFuture<Digest, String> {
       let file_copy = file.clone();
       let store = self.0.clone();
       self

src/rust/engine/src/context.rs

@@ -8,7 +8,8 @@ use std::sync::Arc;
 use boxfuture::BoxFuture;
 use core::{Failure, TypeId};
 use externs;
-use fs::{Digest, File, GetFileDigest, PosixFS, Store, safe_create_dir_all_ioerror, ResettablePool};
+use fs::{Digest, File, PosixFS, Store, safe_create_dir_all_ioerror, ResettablePool,
+         StoreFileByDigest};
 use graph::{EntryId, Graph};
 use handles::maybe_drain_handles;
 use nodes::{DigestFile, Node, NodeFuture};
@@ -104,8 +105,8 @@ impl Context {
   }
 }
 
-impl GetFileDigest<Failure> for Context {
-  fn digest(&self, file: &File) -> BoxFuture<Digest, Failure> {
+impl StoreFileByDigest<Failure> for Context {
+  fn store_by_digest(&self, file: &File) -> BoxFuture<Digest, Failure> {
     self.get(DigestFile(file.clone()))
   }
 }