feature: Impl Client::{supports_try_acquire, try_acquire}

.github/actions/compile-make/action.yml

@@ -0,0 +1,36 @@
+name: Compile make
+description: compile-make
+inputs:
+  version:
+    description: make version
+    required: true
+  workaround:
+    description: enable workaround for _alloc bug
+    required: false
+    default: "false"
+
+runs:
+  using: composite
+  steps:
+    - name: Cache make compiled
+      if: ${{ !startsWith(runner.os, 'windows') }}
+      id: cache-maka
+      uses: actions/cache@v4
+      with:
+        path: /usr/local/bin/make-${{ inputs.version }}
+        key: v1-${{ runner.os }}-make-${{ inputs.version }}
+
+    - name: Make GNU Make from source
+      if: ${{ !startsWith(runner.os, 'windows') && steps.cache-make.outputs.cache-hit != 'true' }}
+      env:
+        VERSION: ${{ inputs.version }}
+        WORKAROUND: ${{ inputs.workaround }}
+      shell: bash
+      run: |
+        curl "https://ftp.gnu.org/gnu/make/make-${VERSION}.tar.gz" | tar xz
+        pushd "make-${VERSION}"
+        ./configure
+        [[ "$WORKAROUND" = "true" ]] && sed -i 's/#if !defined __alloca \&\& !defined __GNU_LIBRARY__/#if !defined __alloca \&\& defined __GNU_LIBRARY__/g; s/#ifndef __GNU_LIBRARY__/#ifdef __GNU_LIBRARY__/g' "./glob/glob.c"
+        make -j 4
+        popd
+        cp -p "make-${VERSION}/make" "/usr/local/bin/make-${VERSION}"

.github/workflows/main.yml

@@ -13,54 +13,37 @@ jobs:
         rust: [stable, beta, nightly]
         os: [ubuntu-latest, macos-14, windows-latest]
     steps:
-    - uses: actions/checkout@master
-    - name: Install Rust (rustup)
-      run: |
-        rustup toolchain install ${{ matrix.rust }} --no-self-update --profile minimal
-        rustup default ${{ matrix.rust }}
-      shell: bash
-
-    - uses: Swatinem/rust-cache@v2
+      - uses: actions/checkout@master
+      - name: Install Rust (rustup)
+        run: |
+          rustup toolchain install ${{ matrix.rust }} --no-self-update --profile minimal
+          rustup default ${{ matrix.rust }}
+        shell: bash
 
-    - run: cargo test --locked
+      - uses: Swatinem/rust-cache@v2
 
-    - name: Cache make compiled
-      if: ${{ !startsWith(matrix.os, 'windows') }}
-      id: cache-make
-      uses: actions/cache@v4
-      with:
-        path: /usr/local/bin/make
-        key: ${{ runner.os }}-make-4.4.1
+      - run: cargo test --locked
 
-    # Compile it from source (temporarily)
-    - name: Make GNU Make from source
-      if: ${{ !startsWith(matrix.os, 'windows') && steps.cache-make.outputs.cache-hit != 'true' }}
-      env:
-        VERSION: "4.4.1"
-      shell: bash
-      run: |
-        curl "https://ftp.gnu.org/gnu/make/make-${VERSION}.tar.gz" | tar xz
-        pushd "make-${VERSION}"
-        ./configure
-        make -j 4
-        popd
-        cp -p "make-${VERSION}/make" /usr/local/bin
+      - name: Compile make 4.4.1
+        uses: ./.github/actions/compile-make
+        with:
+          version: 4.4.1
 
-    - name: Test against GNU Make from source
-      if: ${{ !startsWith(matrix.os, 'windows') }}
-      shell: bash
-      run: cargo test --locked
-      env:
-        MAKE: /usr/local/bin/make
+      - name: Test against GNU Make 4.4.1
+        if: ${{ !startsWith(matrix.os, 'windows') }}
+        shell: bash
+        run: cargo test --locked
+        env:
+          MAKE: /usr/local/bin/make-4.4.1
 
   rustfmt:
     name: Rustfmt
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@master
-    - name: Install Rust
-      run: rustup update stable && rustup default stable && rustup component add rustfmt
-    - run: cargo fmt -- --check
+      - uses: actions/checkout@master
+      - name: Install Rust
+        run: rustup update stable && rustup default stable && rustup component add rustfmt
+      - run: cargo fmt -- --check
 
   publish_docs:
     name: Publish Documentation
@@ -86,12 +69,12 @@ jobs:
       matrix:
         os: [ubuntu-latest, macos-14, windows-latest]
     steps:
-    - uses: actions/checkout@master
-    - name: Install Rust (rustup)
-      run: rustup toolchain install nightly --no-self-update --profile minimal
-      shell: bash
+      - uses: actions/checkout@master
+      - name: Install Rust (rustup)
+        run: rustup toolchain install nightly --no-self-update --profile minimal
+        shell: bash
 
-    - uses: taiki-e/install-action@cargo-hack
-    - uses: Swatinem/rust-cache@v2
+      - uses: taiki-e/install-action@cargo-hack
+      - uses: Swatinem/rust-cache@v2
 
-    - run: cargo hack check --lib --rust-version --ignore-private --locked
+      - run: cargo hack check --lib --rust-version --ignore-private --locked

.gitignore

@@ -1,3 +1,2 @@
 target/
 **/*.rs.bk
-Cargo.lock

Cargo.toml

@@ -13,7 +13,10 @@ edition = "2021"
 rust-version = "1.63"
 
 [target.'cfg(unix)'.dependencies]
-libc = "0.2.72"
+libc = "0.2.87"
+
+[target.'cfg(unix)'.dev-dependencies]
+nix = { version = "0.28.0", features = ["fs"] }
 
 [dev-dependencies]
 tempfile = "3.10.1"

src/lib.rs

@@ -324,6 +324,32 @@ impl Client {
         })
     }
 
+    /// Acquires a token from this jobserver client in a non-blocking way.
+    ///
+    /// # Return value
+    ///
+    /// On successful acquisition of a token an instance of [`Acquired`] is
+    /// returned. This structure, when dropped, will release the token back to
+    /// the jobserver. It's recommended to avoid leaking this value.
+    ///
+    /// # Errors
+    ///
+    /// If an I/O error happens while acquiring a token then this function will
+    /// return immediately with the error. If an error is returned then a token
+    /// was not acquired.
+    ///
+    /// If non-blocking acquire is not supported, the return error will have its `kind()`
+    /// set to [`io::ErrorKind::Unsupported`].
+    pub fn try_acquire(&self) -> io::Result<Option<Acquired>> {
+        let ret = self.inner.try_acquire()?;
+
+        Ok(ret.map(|data| Acquired {
+            client: self.inner.clone(),
+            data,
+            disabled: false,
+        }))
+    }
+
     /// Returns amount of tokens in the read-side pipe.
     ///
     /// # Return value
@@ -607,52 +633,76 @@ fn find_jobserver_auth(var: &str) -> Option<&str> {
         .and_then(|s| s.split(' ').next())
 }
 
-#[test]
-fn no_helper_deadlock() {
-    let x = crate::Client::new(32).unwrap();
-    let _y = x.clone();
-    std::mem::drop(x.into_helper_thread(|_| {}).unwrap());
-}
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    pub(super) fn run_named_fifo_try_acquire_tests(client: &Client) {
+        assert!(client.try_acquire().unwrap().is_none());
+        client.release_raw().unwrap();
 
-#[test]
-fn test_find_jobserver_auth() {
-    let cases = [
-        ("", None),
-        ("-j2", None),
-        ("-j2 --jobserver-auth=3,4", Some("3,4")),
-        ("--jobserver-auth=3,4 -j2", Some("3,4")),
-        ("--jobserver-auth=3,4", Some("3,4")),
-        ("--jobserver-auth=fifo:/myfifo", Some("fifo:/myfifo")),
-        ("--jobserver-auth=", Some("")),
-        ("--jobserver-auth", None),
-        ("--jobserver-fds=3,4", Some("3,4")),
-        ("--jobserver-fds=fifo:/myfifo", Some("fifo:/myfifo")),
-        ("--jobserver-fds=", Some("")),
-        ("--jobserver-fds", None),
-        (
-            "--jobserver-auth=auth-a --jobserver-auth=auth-b",
-            Some("auth-b"),
-        ),
-        (
-            "--jobserver-auth=auth-b --jobserver-auth=auth-a",
-            Some("auth-a"),
-        ),
-        ("--jobserver-fds=fds-a --jobserver-fds=fds-b", Some("fds-b")),
-        ("--jobserver-fds=fds-b --jobserver-fds=fds-a", Some("fds-a")),
-        (
-            "--jobserver-auth=auth-a --jobserver-fds=fds-a --jobserver-auth=auth-b",
-            Some("auth-b"),
-        ),
-        (
-            "--jobserver-fds=fds-a --jobserver-auth=auth-a --jobserver-fds=fds-b",
-            Some("auth-a"),
-        ),
-    ];
-    for (var, expected) in cases {
-        let actual = find_jobserver_auth(var);
-        assert_eq!(
-            actual, expected,
-            "expect {expected:?}, got {actual:?}, input `{var:?}`"
-        );
+        let acquired = client.try_acquire().unwrap().unwrap();
+        assert!(client.try_acquire().unwrap().is_none());
+
+        drop(acquired);
+        client.try_acquire().unwrap().unwrap();
+    }
+
+    #[cfg(not(unix))]
+    #[test]
+    fn test_try_acquire() {
+        let client = Client::new(0).unwrap();
+
+        run_named_fifo_try_acquire_tests(&client);
+    }
+
+    #[test]
+    fn no_helper_deadlock() {
+        let x = crate::Client::new(32).unwrap();
+        let _y = x.clone();
+        std::mem::drop(x.into_helper_thread(|_| {}).unwrap());
+    }
+
+    #[test]
+    fn test_find_jobserver_auth() {
+        let cases = [
+            ("", None),
+            ("-j2", None),
+            ("-j2 --jobserver-auth=3,4", Some("3,4")),
+            ("--jobserver-auth=3,4 -j2", Some("3,4")),
+            ("--jobserver-auth=3,4", Some("3,4")),
+            ("--jobserver-auth=fifo:/myfifo", Some("fifo:/myfifo")),
+            ("--jobserver-auth=", Some("")),
+            ("--jobserver-auth", None),
+            ("--jobserver-fds=3,4", Some("3,4")),
+            ("--jobserver-fds=fifo:/myfifo", Some("fifo:/myfifo")),
+            ("--jobserver-fds=", Some("")),
+            ("--jobserver-fds", None),
+            (
+                "--jobserver-auth=auth-a --jobserver-auth=auth-b",
+                Some("auth-b"),
+            ),
+            (
+                "--jobserver-auth=auth-b --jobserver-auth=auth-a",
+                Some("auth-a"),
+            ),
+            ("--jobserver-fds=fds-a --jobserver-fds=fds-b", Some("fds-b")),
+            ("--jobserver-fds=fds-b --jobserver-fds=fds-a", Some("fds-a")),
+            (
+                "--jobserver-auth=auth-a --jobserver-fds=fds-a --jobserver-auth=auth-b",
+                Some("auth-b"),
+            ),
+            (
+                "--jobserver-fds=fds-a --jobserver-auth=auth-a --jobserver-fds=fds-b",
+                Some("auth-a"),
+            ),
+        ];
+        for (var, expected) in cases {
+            let actual = find_jobserver_auth(var);
+            assert_eq!(
+                actual, expected,
+                "expect {expected:?}, got {actual:?}, input `{var:?}`"
+            );
+        }
     }
 }