feat(sync-only): add support for removing async runtime dependency altogether (#56)

Author: zkat

Cargo.toml

@@ -31,7 +31,7 @@ tokio = { version = "1.12.0", features = [
     "fs",
     "io-util",
     "macros",
-    "rt"
+    "rt",
 ], optional = true }
 tokio-stream = { version = "0.1.7", features = ["io-util"], optional = true }
 walkdir = "2.3.2"
@@ -49,7 +49,7 @@ tokio = { version = "1.12.0", features = [
     "macros",
     "rt",
     "rt-multi-thread",
-]}
+] }
 
 [[bench]]
 name = "benchmarks"

README.md

@@ -38,7 +38,11 @@ Minimum supported Rust version is `1.43.0`.
 
 ## Features
 
-- First-class async support, using either [`async-std`](https://crates.io/crates/async-std) or [`tokio`](https://crates.io/crates/tokio) as its runtime. Sync APIs are available but secondary
+- First-class async support, using either
+  [`async-std`](https://crates.io/crates/async-std) or
+  [`tokio`](https://crates.io/crates/tokio) as its runtime. Sync APIs are
+  available but secondary. You can also use sync APIs only and remove the
+  async runtime dependency.
 - `std::fs`-style API
 - Extraction by key or by content address (shasum, etc)
 - [Subresource Integrity](#integrity) web standard support
@@ -56,21 +60,37 @@ Minimum supported Rust version is `1.43.0`.
 - [`miette`](https://crates.io/crates/miette) integration for detailed, helpful error reporting.
 - Punches nazis
 
-`async-std` is the default async runtime. To use `tokio` instead, turn off default features and enable the `tokio-runtime` feature, like this:
+`async-std` is the default async runtime. To use `tokio` instead, turn off
+default features and enable the `tokio-runtime` feature, like this:
 
 ```toml
 [dependencies]
-cacache = { version = "*", default-features = false, features = ["tokio-runtime"] }
+cacache = { version = "*", default-features = false, features = ["tokio-runtime", "mmap"] }
+```
+
+You can also remove async APIs altogether, including removing async runtime
+dependency:
+
+```toml
+[dependencies]
+cacache = { version = "*", default-features = false, features = ["mmap"] }
 ```
 
 Experimental support for symlinking to existing files is provided via the
 "link_to" feature.
 
 ## Contributing
 
-The cacache team enthusiastically welcomes contributions and project participation! There's a bunch of things you can do if you want to contribute! The [Contributor Guide](CONTRIBUTING.md) has all the information you need for everything from reporting bugs to contributing entire new features. Please don't hesitate to jump in if you'd like to, or even ask us questions if something isn't clear.
+The cacache team enthusiastically welcomes contributions and project
+participation! There's a bunch of things you can do if you want to contribute!
+The [Contributor Guide](CONTRIBUTING.md) has all the information you need for
+everything from reporting bugs to contributing entire new features. Please
+don't hesitate to jump in if you'd like to, or even ask us questions if
+something isn't clear.
 
-All participants and maintainers in this project are expected to follow [Code of Conduct](CODE_OF_CONDUCT.md), and just generally be excellent to each other.
+All participants and maintainers in this project are expected to follow [Code
+of Conduct](CODE_OF_CONDUCT.md), and just generally be excellent to each
+other.
 
 Happy hacking!
 

benches/benchmarks.rs

@@ -62,6 +62,7 @@ fn baseline_read_many_sync(c: &mut Criterion) {
     });
 }
 
+#[cfg(any(feature = "async-std", feature = "tokio"))]
 fn baseline_read_async(c: &mut Criterion) {
     let tmp = tempfile::tempdir().unwrap();
     let path = tmp.path().join("test_file");
@@ -74,6 +75,7 @@ fn baseline_read_async(c: &mut Criterion) {
     });
 }
 
+#[cfg(any(feature = "async-std", feature = "tokio"))]
 fn baseline_read_many_async(c: &mut Criterion) {
     let tmp = tempfile::tempdir().unwrap();
     let paths: Vec<_> = (0..)
@@ -188,6 +190,7 @@ fn read_hash_sync_big_data_xxh3(c: &mut Criterion) {
     });
 }
 
+#[cfg(any(feature = "async-std", feature = "tokio"))]
 fn read_hash_many_async(c: &mut Criterion) {
     let tmp = tempfile::tempdir().unwrap();
     let cache = tmp.path().to_owned();
@@ -209,6 +212,7 @@ fn read_hash_many_async(c: &mut Criterion) {
     });
 }
 
+#[cfg(any(feature = "async-std", feature = "tokio"))]
 fn read_hash_async(c: &mut Criterion) {
     let tmp = tempfile::tempdir().unwrap();
     let cache = tmp.path().to_owned();
@@ -219,6 +223,7 @@ fn read_hash_async(c: &mut Criterion) {
     });
 }
 
+#[cfg(any(feature = "async-std", feature = "tokio"))]
 fn read_async(c: &mut Criterion) {
     let tmp = tempfile::tempdir().unwrap();
     let cache = tmp.path().to_owned();
@@ -229,6 +234,7 @@ fn read_async(c: &mut Criterion) {
     });
 }
 
+#[cfg(any(feature = "async-std", feature = "tokio"))]
 fn read_hash_async_big_data(c: &mut Criterion) {
     let tmp = tempfile::tempdir().unwrap();
     let cache = tmp.path().to_owned();
@@ -271,6 +277,8 @@ fn write_hash_xxh3(c: &mut Criterion) {
         })
     });
 }
+
+#[cfg(any(feature = "async-std", feature = "tokio"))]
 fn write_hash_async(c: &mut Criterion) {
     let tmp = tempfile::tempdir().unwrap();
     let cache = tmp.path().to_owned();
@@ -285,6 +293,7 @@ fn write_hash_async(c: &mut Criterion) {
     });
 }
 
+#[cfg(any(feature = "async-std", feature = "tokio"))]
 fn write_hash_async_xxh3(c: &mut Criterion) {
     let tmp = tempfile::tempdir().unwrap();
     let cache = tmp.path().to_owned();
@@ -316,6 +325,7 @@ fn create_tmpfile(tmp: &tempfile::TempDir, buf: &[u8]) -> PathBuf {
 }
 
 #[cfg(feature = "link_to")]
+#[cfg(any(feature = "async-std", feature = "tokio"))]
 fn link_to_async(c: &mut Criterion) {
     let tmp = tempfile::tempdir().unwrap();
     let target = create_tmpfile(&tmp, b"hello world");
@@ -338,7 +348,7 @@ fn link_to_async(c: &mut Criterion) {
     });
 }
 
-#[cfg(feature = "link_to")]
+#[cfg(all(feature = "link_to", any(feature = "async-std", feature = "tokio")))]
 fn link_to_hash_async(c: &mut Criterion) {
     let tmp = tempfile::tempdir().unwrap();
     let target = create_tmpfile(&tmp, b"hello world");
@@ -384,35 +394,55 @@ criterion_group!(
     benches,
     baseline_read_sync,
     baseline_read_many_sync,
-    baseline_read_async,
-    baseline_read_many_async,
-    read_hash_async,
-    read_hash_many_async,
-    read_async,
     write_hash,
     write_hash_xxh3,
-    write_hash_async,
-    write_hash_async_xxh3,
     read_hash_sync,
     read_hash_sync_xxh3,
     read_hash_many_sync,
     read_hash_many_sync_xxh3,
     read_sync,
-    read_hash_async_big_data,
     read_hash_sync_big_data,
     read_hash_sync_big_data_xxh3,
 );
 
-#[cfg(feature = "link_to")]
+#[cfg(any(feature = "async-std", feature = "tokio"))]
 criterion_group!(
-    link_to_benches,
-    link_to_async,
-    link_to_hash_async,
-    link_to_sync,
-    link_to_hash_sync
+    benches_async,
+    baseline_read_async,
+    baseline_read_many_async,
+    read_hash_async,
+    read_hash_many_async,
+    read_async,
+    write_hash_async,
+    write_hash_async_xxh3,
+    read_hash_async_big_data,
 );
 
+#[cfg(all(feature = "link_to", any(feature = "async-std", feature = "tokio")))]
+criterion_group!(link_to_benches_async, link_to_async, link_to_hash_async,);
+
 #[cfg(feature = "link_to")]
+criterion_group!(link_to_benches, link_to_sync, link_to_hash_sync);
+
+#[cfg(all(
+    feature = "link_to",
+    not(any(feature = "async-std", feature = "tokio"))
+))]
 criterion_main!(benches, link_to_benches);
-#[cfg(not(feature = "link_to"))]
+#[cfg(all(
+    not(feature = "link_to"),
+    any(feature = "async-std", feature = "tokio")
+))]
+criterion_main!(benches, benches_async);
+#[cfg(all(feature = "link_to", any(feature = "async-std", feature = "tokio")))]
+criterion_main!(
+    benches,
+    benches_async,
+    link_to_benches,
+    link_to_benches_async
+);
+#[cfg(all(
+    not(feature = "link_to"),
+    not(any(feature = "async-std", feature = "tokio"))
+))]
 criterion_main!(benches);

src/async_lib.rs

@@ -121,8 +121,8 @@ pub async fn create_named_tempfile(tmp_path: std::path::PathBuf) -> crate::Resul
 #[inline]
 pub async fn create_named_tempfile(tmp_path: std::path::PathBuf) -> crate::Result<NamedTempFile> {
     let cloned = tmp_path.clone();
-    Ok(spawn_blocking(|| NamedTempFile::new_in(tmp_path))
+    spawn_blocking(|| NamedTempFile::new_in(tmp_path))
         .await
         .unwrap()
-        .with_context(|| format!("Failed to create a temp file at {}", cloned.display()))?)
+        .with_context(|| format!("Failed to create a temp file at {}", cloned.display()))
 }

src/content/linkto.rs

@@ -2,9 +2,12 @@ use ssri::{Algorithm, Integrity, IntegrityOpts};
 use std::fs::DirBuilder;
 use std::fs::File;
 use std::path::{Path, PathBuf};
+#[cfg(any(feature = "async-std", feature = "tokio"))]
 use std::pin::Pin;
+#[cfg(any(feature = "async-std", feature = "tokio"))]
 use std::task::{Context, Poll};
 
+#[cfg(any(feature = "async-std", feature = "tokio"))]
 use crate::async_lib::AsyncRead;
 use crate::content::path;
 use crate::errors::{IoErrorExt, Result};
@@ -103,6 +106,7 @@ impl std::io::Read for ToLinker {
 /// An `AsyncRead`-like type that calculates the integrity of a file as it is
 /// read. When the linker is committed, a symlink is created from the cache to
 /// the target file using the integrity computed from the file's contents.
+#[cfg(any(feature = "async-std", feature = "tokio"))]
 pub struct AsyncToLinker {
     /// The path to the target file that will be symlinked from the cache.
     target: PathBuf,
@@ -114,6 +118,7 @@ pub struct AsyncToLinker {
     builder: IntegrityOpts,
 }
 
+#[cfg(any(feature = "async-std", feature = "tokio"))]
 impl AsyncRead for AsyncToLinker {
     #[cfg(feature = "async-std")]
     fn poll_read(
@@ -143,6 +148,7 @@ impl AsyncRead for AsyncToLinker {
     }
 }
 
+#[cfg(any(feature = "async-std", feature = "tokio"))]
 impl AsyncToLinker {
     pub async fn new(cache: &Path, algo: Algorithm, target: &Path) -> Result<Self> {
         let file = crate::async_lib::File::open(target)
@@ -216,6 +222,7 @@ mod tests {
         assert_eq!(std::fs::read(cpath).unwrap(), b"hello world");
     }
 
+    #[cfg(any(feature = "async-std", feature = "tokio"))]
     #[async_test]
     async fn basic_async_link() {
         let tmp = tempfile::tempdir().unwrap();

src/content/read.rs

@@ -1,7 +1,9 @@
 use std::fs::{self, File};
 use std::io::Read;
 use std::path::Path;
+#[cfg(any(feature = "async-std", feature = "tokio"))]
 use std::pin::Pin;
+#[cfg(any(feature = "async-std", feature = "tokio"))]
 use std::task::{Context, Poll};
 
 #[cfg(feature = "async-std")]
@@ -11,6 +13,7 @@ use tokio::io::AsyncReadExt;
 
 use ssri::{Algorithm, Integrity, IntegrityChecker};
 
+#[cfg(any(feature = "async-std", feature = "tokio"))]
 use crate::async_lib::AsyncRead;
 use crate::content::path;
 use crate::errors::{IoErrorExt, Result};
@@ -34,11 +37,13 @@ impl Reader {
     }
 }
 
+#[cfg(any(feature = "async-std", feature = "tokio"))]
 pub struct AsyncReader {
     fd: crate::async_lib::File,
     checker: IntegrityChecker,
 }
 
+#[cfg(any(feature = "async-std", feature = "tokio"))]
 impl AsyncRead for AsyncReader {
     #[cfg(feature = "async-std")]
     fn poll_read(
@@ -68,6 +73,7 @@ impl AsyncRead for AsyncReader {
     }
 }
 
+#[cfg(any(feature = "async-std", feature = "tokio"))]
 impl AsyncReader {
     pub fn check(self) -> Result<Algorithm> {
         Ok(self.checker.result()?)
@@ -87,6 +93,7 @@ pub fn open(cache: &Path, sri: Integrity) -> Result<Reader> {
     })
 }
 
+#[cfg(any(feature = "async-std", feature = "tokio"))]
 pub async fn open_async(cache: &Path, sri: Integrity) -> Result<AsyncReader> {
     let cpath = path::content_path(cache, &sri);
     Ok(AsyncReader {
@@ -112,6 +119,7 @@ pub fn read(cache: &Path, sri: &Integrity) -> Result<Vec<u8>> {
     Ok(ret)
 }
 
+#[cfg(any(feature = "async-std", feature = "tokio"))]
 pub async fn read_async<'a>(cache: &'a Path, sri: &'a Integrity) -> Result<Vec<u8>> {
     let cpath = path::content_path(cache, sri);
     let ret = crate::async_lib::read(&cpath).await.with_context(|| {
@@ -158,6 +166,7 @@ pub fn copy(cache: &Path, sri: &Integrity, to: &Path) -> Result<u64> {
     Ok(size as u64)
 }
 
+#[cfg(any(feature = "async-std", feature = "tokio"))]
 pub async fn copy_unchecked_async<'a>(
     cache: &'a Path,
     sri: &'a Integrity,
@@ -176,6 +185,7 @@ pub async fn copy_unchecked_async<'a>(
     Ok(())
 }
 
+#[cfg(any(feature = "async-std", feature = "tokio"))]
 pub async fn copy_async<'a>(cache: &'a Path, sri: &'a Integrity, to: &'a Path) -> Result<u64> {
     copy_unchecked_async(cache, sri, to).await?;
     let mut reader = open_async(cache, sri.clone()).await?;
@@ -230,6 +240,7 @@ pub fn hard_link(cache: &Path, sri: &Integrity, to: &Path) -> Result<()> {
     Ok(())
 }
 
+#[cfg(any(feature = "async-std", feature = "tokio"))]
 pub async fn hard_link_async(cache: &Path, sri: &Integrity, to: &Path) -> Result<()> {
     hard_link_unchecked(cache, sri, to)?;
     let mut reader = open_async(cache, sri.clone()).await?;
@@ -259,6 +270,7 @@ pub fn has_content(cache: &Path, sri: &Integrity) -> Option<Integrity> {
     }
 }
 
+#[cfg(any(feature = "async-std", feature = "tokio"))]
 pub async fn has_content_async(cache: &Path, sri: &Integrity) -> Option<Integrity> {
     if crate::async_lib::metadata(path::content_path(cache, sri))
         .await

src/content/rm.rs

@@ -16,6 +16,7 @@ pub fn rm(cache: &Path, sri: &Integrity) -> Result<()> {
     Ok(())
 }
 
+#[cfg(any(feature = "async-std", feature = "tokio"))]
 pub async fn rm_async(cache: &Path, sri: &Integrity) -> Result<()> {
     crate::async_lib::remove_file(path::content_path(cache, sri))
         .await