Remove async_trait dependency, MSRV CI (#37)

Requires Rust v1.75 - old enough to release now

Also fixes a few pedantic clippy things and CI improvements

.github/workflows/test.yml

@@ -15,7 +15,9 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout sources
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
+      - uses: Swatinem/rust-cache@v2
+        if: github.event_name != 'release' && github.event_name != 'workflow_dispatch'
 
       - run: |
           rustc --version
@@ -34,3 +36,25 @@ jobs:
       - run: cargo test
       - name: Check semver
         uses: obi1kenobi/cargo-semver-checks-action@v2
+
+  msrv:
+    name: Test MSRV
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: Swatinem/rust-cache@v2
+        if: github.event_name != 'release' && github.event_name != 'workflow_dispatch'
+      - name: Read crate metadata
+        id: metadata
+        run: echo "rust-version=$(sed -ne 's/rust-version *= *\"\(.*\)\"/\1/p' Cargo.toml)" >> $GITHUB_OUTPUT
+      - name: Install Rust
+        uses: dtolnay/rust-toolchain@stable
+        with:
+          toolchain: ${{ steps.metadata.outputs.rust-version }}
+      - run: cargo test --all-targets --all-features
+      - run: cargo test --features http-async
+      - run: cargo test --features mmap-async-tokio
+      - run: cargo test --features tilejson
+      - run: cargo test --features s3-async-native
+      - run: cargo test --features s3-async-rustls
+      - run: cargo test

Cargo.toml

@@ -1,13 +1,13 @@
 [package]
 name = "pmtiles"
-version = "0.8.0"
+version = "0.9.0"
 edition = "2021"
 authors = ["Luke Seelenbinder <[email protected]>"]
 license = "MIT OR Apache-2.0"
 description = "Implementation of the PMTiles v3 spec with multiple sync and async backends."
 repository = "https://github.com/stadiamaps/pmtiles-rs"
 keywords = ["pmtiles", "gis", "geo"]
-rust-version = "1.68.2"
+rust-version = "1.75.0"
 categories = ["science::geo"]
 
 [features]
@@ -35,7 +35,6 @@ __async-s3-rustls = ["rust-s3?/tokio-rustls-tls"]
 # TODO: determine how we want to handle compression in async & sync environments
 async-compression = { version = "0.4", features = ["gzip", "zstd", "brotli"] }
 async-recursion = "1"
-async-trait = "0.1"
 bytes = "1"
 fmmap = { version = "0.3", default-features = false, optional = true }
 hilbert_2d = "1"

src/async_reader.rs

@@ -2,8 +2,9 @@
 //        so any file larger than 4GB, or an untrusted file with bad data may crash.
 #![allow(clippy::cast_possible_truncation)]
 
+use std::future::Future;
+
 use async_recursion::async_recursion;
-use async_trait::async_trait;
 use bytes::Bytes;
 #[cfg(feature = "__async")]
 use tokio::io::AsyncReadExt;
@@ -213,23 +214,25 @@ impl<B: AsyncBackend + Sync + Send, C: DirectoryCache + Sync + Send> AsyncPmTile
     }
 }
 
-#[async_trait]
 pub trait AsyncBackend {
     /// Reads exactly `length` bytes starting at `offset`
-    async fn read_exact(&self, offset: usize, length: usize) -> PmtResult<Bytes>;
+    fn read_exact(
+        &self,
+        offset: usize,
+        length: usize,
+    ) -> impl Future<Output = PmtResult<Bytes>> + Send;
 
     /// Reads up to `length` bytes starting at `offset`.
-    async fn read(&self, offset: usize, length: usize) -> PmtResult<Bytes>;
+    fn read(&self, offset: usize, length: usize) -> impl Future<Output = PmtResult<Bytes>> + Send;
 }
 
 #[cfg(test)]
 #[cfg(feature = "mmap-async-tokio")]
 mod tests {
+    use super::AsyncPmTilesReader;
     use crate::tests::{RASTER_FILE, VECTOR_FILE};
     use crate::MmapBackend;
 
-    use super::AsyncPmTilesReader;
-
     #[tokio::test]
     async fn open_sanity_check() {
         let backend = MmapBackend::try_from(RASTER_FILE).await.unwrap();

src/backend_http.rs

@@ -1,4 +1,3 @@
-use async_trait::async_trait;
 use bytes::Bytes;
 use reqwest::header::{HeaderValue, RANGE};
 use reqwest::{Client, IntoUrl, Method, Request, StatusCode, Url};
@@ -46,7 +45,6 @@ impl HttpBackend {
     }
 }
 
-#[async_trait]
 impl AsyncBackend for HttpBackend {
     async fn read_exact(&self, offset: usize, length: usize) -> PmtResult<Bytes> {
         let data = self.read(offset, length).await?;
@@ -86,14 +84,13 @@ impl AsyncBackend for HttpBackend {
 #[cfg(test)]
 mod tests {
     use super::*;
-    use crate::async_reader::AsyncPmTilesReader;
 
     static TEST_URL: &str =
         "https://protomaps.github.io/PMTiles/protomaps(vector)ODbL_firenze.pmtiles";
 
     #[tokio::test]
     async fn basic_http_test() {
-        let client = reqwest::Client::builder().use_rustls_tls().build().unwrap();
+        let client = Client::builder().use_rustls_tls().build().unwrap();
         let backend = HttpBackend::try_from(client, TEST_URL).unwrap();
 
         AsyncPmTilesReader::try_from_source(backend).await.unwrap();

src/backend_mmap.rs

@@ -1,7 +1,6 @@
 use std::io;
 use std::path::Path;
 
-use async_trait::async_trait;
 use bytes::{Buf, Bytes};
 use fmmap::tokio::{AsyncMmapFile, AsyncMmapFileExt as _, AsyncOptions};
 
@@ -49,7 +48,6 @@ impl From<fmmap::error::Error> for PmtError {
     }
 }
 
-#[async_trait]
 impl AsyncBackend for MmapBackend {
     async fn read_exact(&self, offset: usize, length: usize) -> PmtResult<Bytes> {
         if self.file.len() >= offset + length {

src/backend_s3.rs

@@ -1,4 +1,3 @@
-use async_trait::async_trait;
 use bytes::Bytes;
 use s3::Bucket;
 
@@ -43,7 +42,6 @@ impl S3Backend {
     }
 }
 
-#[async_trait]
 impl AsyncBackend for S3Backend {
     async fn read_exact(&self, offset: usize, length: usize) -> PmtResult<Bytes> {
         let data = self.read(offset, length).await?;

src/cache.rs

@@ -1,8 +1,7 @@
 use std::collections::HashMap;
+use std::future::Future;
 use std::sync::{Arc, RwLock};
 
-use async_trait::async_trait;
-
 use crate::directory::{DirEntry, Directory};
 
 pub enum DirCacheResult {
@@ -20,20 +19,25 @@ impl From<Option<&DirEntry>> for DirCacheResult {
     }
 }
 
-/// A cache for PMTiles directories.
-#[async_trait]
+/// A cache for `PMTiles` directories.
 pub trait DirectoryCache {
     /// Get a directory from the cache, using the offset as a key.
-    async fn get_dir_entry(&self, offset: usize, tile_id: u64) -> DirCacheResult;
+    fn get_dir_entry(
+        &self,
+        offset: usize,
+        tile_id: u64,
+    ) -> impl Future<Output = DirCacheResult> + Send;
 
     /// Insert a directory into the cache, using the offset as a key.
     /// Note that cache must be internally mutable.
-    async fn insert_dir(&self, offset: usize, directory: Directory);
+    fn insert_dir(&self, offset: usize, directory: Directory) -> impl Future<Output = ()> + Send;
 }
 
 pub struct NoCache;
 
-#[async_trait]
+// TODO: Remove #[allow] after switching to Rust/Clippy v1.78+ in CI
+//       See https://github.com/rust-lang/rust-clippy/pull/12323
+#[allow(clippy::no_effect_underscore_binding)]
 impl DirectoryCache for NoCache {
     #[inline]
     async fn get_dir_entry(&self, _offset: usize, _tile_id: u64) -> DirCacheResult {
@@ -50,7 +54,6 @@ pub struct HashMapCache {
     pub cache: Arc<RwLock<HashMap<usize, Directory>>>,
 }
 
-#[async_trait]
 impl DirectoryCache for HashMapCache {
     async fn get_dir_entry(&self, offset: usize, tile_id: u64) -> DirCacheResult {
         if let Some(dir) = self.cache.read().unwrap().get(&offset) {