Trying block_on

blockontest/Cargo.lock

@@ -0,0 +1,179 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "addr2line"
+version = "0.21.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8a30b2e23b9e17a9f90641c7ab1549cd9b44f296d3ccbf309d2863cfe398a0cb"
+dependencies = [
+ "gimli",
+]
+
+[[package]]
+name = "adler"
+version = "1.0.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f26201604c87b1e01bd3d98f8d5d9a8fcbb815e8cedb41ffccbeb4bf593a35fe"
+
+[[package]]
+name = "async-recursion"
+version = "1.0.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5fd55a5ba1179988837d24ab4c7cc8ed6efdeff578ede0416b4225a5fca35bd0"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
+[[package]]
+name = "backtrace"
+version = "0.3.69"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2089b7e3f35b9dd2d0ed921ead4f6d318c27680d4a5bd167b3ee120edb105837"
+dependencies = [
+ "addr2line",
+ "cc",
+ "cfg-if",
+ "libc",
+ "miniz_oxide",
+ "object",
+ "rustc-demangle",
+]
+
+[[package]]
+name = "blockontest"
+version = "0.1.0"
+dependencies = [
+ "async-recursion",
+ "tokio",
+]
+
+[[package]]
+name = "bytes"
+version = "1.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a2bd12c1caf447e69cd4528f47f94d203fd2582878ecb9e9465484c4148a8223"
+
+[[package]]
+name = "cc"
+version = "1.0.83"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f1174fb0b6ec23863f8b971027804a42614e347eafb0a95bf0b12cdae21fc4d0"
+dependencies = [
+ "libc",
+]
+
+[[package]]
+name = "cfg-if"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "baf1de4339761588bc0619e3cbc0120ee582ebb74b53b4efbf79117bd2da40fd"
+
+[[package]]
+name = "gimli"
+version = "0.28.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6fb8d784f27acf97159b40fc4db5ecd8aa23b9ad5ef69cdd136d3bc80665f0c0"
+
+[[package]]
+name = "libc"
+version = "0.2.147"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b4668fb0ea861c1df094127ac5f1da3409a82116a4ba74fca2e58ef927159bb3"
+
+[[package]]
+name = "memchr"
+version = "2.6.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8f232d6ef707e1956a43342693d2a31e72989554d58299d7a88738cc95b0d35c"
+
+[[package]]
+name = "miniz_oxide"
+version = "0.7.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e7810e0be55b428ada41041c41f32c9f1a42817901b4ccf45fa3d4b6561e74c7"
+dependencies = [
+ "adler",
+]
+
+[[package]]
+name = "object"
+version = "0.32.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9cf5f9dd3933bd50a9e1f149ec995f39ae2c496d31fd772c1fd45ebc27e902b0"
+dependencies = [
+ "memchr",
+]
+
+[[package]]
+name = "pin-project-lite"
+version = "0.2.13"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8afb450f006bf6385ca15ef45d71d2288452bc3683ce2e2cacc0d18e4be60b58"
+
+[[package]]
+name = "proc-macro2"
+version = "1.0.66"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "18fb31db3f9bddb2ea821cde30a9f70117e3f119938b5ee630b7403aa6e2ead9"
+dependencies = [
+ "unicode-ident",
+]
+
+[[package]]
+name = "quote"
+version = "1.0.33"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5267fca4496028628a95160fc423a33e8b2e6af8a5302579e322e4b520293cae"
+dependencies = [
+ "proc-macro2",
+]
+
+[[package]]
+name = "rustc-demangle"
+version = "0.1.23"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d626bb9dae77e28219937af045c257c28bfd3f69333c512553507f5f9798cb76"
+
+[[package]]
+name = "syn"
+version = "2.0.32"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "239814284fd6f1a4ffe4ca893952cdd93c224b6a1571c9a9eadd670295c0c9e2"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "unicode-ident",
+]
+
+[[package]]
+name = "tokio"
+version = "1.32.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "17ed6077ed6cd6c74735e21f37eb16dc3935f96878b1fe961074089cc80893f9"
+dependencies = [
+ "backtrace",
+ "bytes",
+ "pin-project-lite",
+ "tokio-macros",
+]
+
+[[package]]
+name = "tokio-macros"
+version = "2.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "630bdcf245f78637c13ec01ffae6187cca34625e8c63150d424b59e55af2675e"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
+[[package]]
+name = "unicode-ident"
+version = "1.0.11"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "301abaae475aa91687eb82514b328ab47a211a533026cb25fc3e519b86adfc3c"

blockontest/Cargo.toml

@@ -0,0 +1,10 @@
+[package]
+name = "blockontest"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+async-recursion = "1.0.5"
+tokio = { version = "1.32.0", features = ["rt", "fs", "io-util", "macros"] }

blockontest/README.md

@@ -0,0 +1,4 @@
+# BlockOnTest
+
+Checking if `block_on` can run the inner context as async while the outer
+context gets paused.

blockontest/src/main.rs

@@ -0,0 +1,57 @@
+use std::{
+    future::Future,
+    path::{Path, PathBuf},
+};
+
+use tokio::{
+    fs::File,
+    io::{AsyncBufReadExt, BufReader}, runtime::Handle,
+};
+
+pub async fn async_walk_files<F, T>(start: &Path, on_file: T)
+where
+    T: Fn(PathBuf) -> F + Send + std::marker::Sync + std::marker::Copy,
+    F: Future<Output = ()> + Send,
+{
+    inner_async_walk_files(start, start, on_file).await;
+}
+
+#[async_recursion::async_recursion]
+async fn inner_async_walk_files<T, F>(base: &Path, current: &Path, on_file: T)
+where
+    T: Fn(PathBuf) -> F + Send + std::marker::Sync + std::marker::Copy,
+    F: Future<Output = ()> + Send,
+{
+    println!("Walk: {:?}", current);
+    let dir_contents = tokio::fs::read_dir(current).await;
+    if let Ok(mut content) = dir_contents {
+        while let Ok(Some(entry)) = content.next_entry().await {
+            let entry = entry.path();
+            if entry.is_file() {
+                on_file(entry).await;
+            } else if entry.is_dir() {
+                inner_async_walk_files(base, &entry, on_file).await;
+            }
+        }
+    }
+}
+
+#[tokio::main(flavor = "current_thread")]
+async fn main() {
+    async_walk_files(Path::new(".."), |path| async move {
+        // This doesn't work 'cause, on a single thread runtime, the working thread would be
+        // blocked, and Tokio doesn't like it.
+        let handle = Handle::current();
+        handle.block_on(async move {
+            println!("File: {:?}", path);
+            let file = File::open(&path).await.unwrap();
+            let reader = BufReader::new(file);
+            let mut lines = reader.lines();
+
+            while let Ok(Some(line)) = lines.next_line().await {
+                println!("Line: {path:?} -> {line:?}");
+            }
+        })
+    })
+    .await;
+}