Optimize fetch_crate_cratesio for exact version

If `version_req` requests a specific version instead of a range, then
there is no need to pull all versions available from
https://crates.io/api/v1/crates

Signed-off-by: Jiahao XU <Jiahao_XU@outlook.com>

crates/binstalk/src/drivers/crates_io.rs

@@ -1,8 +1,8 @@
 use std::path::PathBuf;
 
 use cargo_toml::Manifest;
-use compact_str::CompactString;
-use semver::VersionReq;
+use compact_str::{CompactString, ToCompactString};
+use semver::{Comparator, Op as ComparatorOp, Version as SemVersion, VersionReq};
 use serde::Deserialize;
 use tracing::debug;
 
@@ -21,38 +21,68 @@ mod vfs;
 mod visitor;
 use visitor::ManifestVisitor;
 
-#[derive(Deserialize)]
-struct CrateInfo {
-    #[serde(rename = "crate")]
-    inner: CrateInfoInner,
-}
+async fn is_crate_yanked(
+    client: &Client,
+    name: &str,
+    version: &str,
+) -> Result<bool, BinstallError> {
+    #[derive(Deserialize)]
+    struct CrateInfo {
+        version: Inner,
+    }
+
+    #[derive(Deserialize)]
+    struct Inner {
+        yanked: bool,
+    }
 
-#[derive(Deserialize)]
-struct CrateInfoInner {
-    max_stable_version: CompactString,
-}
+    // Fetch / update index
+    debug!("Looking up crate information");
 
-#[derive(Deserialize)]
-struct Versions {
-    versions: Vec<Version>,
-}
+    let response = client
+        .get(Url::parse(&format!(
+            "https://crates.io/api/v1/crates/{name}/{version}"
+        ))?)
+        .send(true)
+        .await
+        .map_err(|err| {
+            BinstallError::CratesIoApi(Box::new(CratesIoApiError {
+                crate_name: name.into(),
+                err,
+            }))
+        })?;
+
+    let info: CrateInfo = response.json().await?;
 
-#[derive(Deserialize)]
-struct Version {
-    num: CompactString,
-    yanked: bool,
+    Ok(info.version.yanked)
 }
 
-/// Find the crate by name, get its latest stable version matches `version_req`,
-/// retrieve its Cargo.toml and infer all its bins.
-pub async fn fetch_crate_cratesio(
-    client: Client,
+async fn fetch_crate_cratesio_version_matched(
+    client: &Client,
     name: &str,
     version_req: &VersionReq,
-    crates_io_rate_limit: &CratesIoRateLimit,
-) -> Result<Manifest<Meta>, BinstallError> {
-    // Wait until we can make another request to crates.io
-    crates_io_rate_limit.tick().await;
+) -> Result<CompactString, BinstallError> {
+    #[derive(Deserialize)]
+    struct CrateInfo {
+        #[serde(rename = "crate")]
+        inner: CrateInfoInner,
+    }
+
+    #[derive(Deserialize)]
+    struct CrateInfoInner {
+        max_stable_version: CompactString,
+    }
+
+    #[derive(Deserialize)]
+    struct Versions {
+        versions: Vec<Version>,
+    }
+
+    #[derive(Deserialize)]
+    struct Version {
+        num: CompactString,
+        yanked: bool,
+    }
 
     // Fetch / update index
     debug!("Looking up crate information");
@@ -106,6 +136,48 @@ pub async fn fetch_crate_cratesio(
 
     debug!("Found information for crate version: '{version}'");
 
+    Ok(version)
+}
+
+/// Find the crate by name, get its latest stable version matches `version_req`,
+/// retrieve its Cargo.toml and infer all its bins.
+pub async fn fetch_crate_cratesio(
+    client: Client,
+    name: &str,
+    version_req: &VersionReq,
+    crates_io_rate_limit: &CratesIoRateLimit,
+) -> Result<Manifest<Meta>, BinstallError> {
+    // Wait until we can make another request to crates.io
+    crates_io_rate_limit.tick().await;
+
+    let version = match version_req.comparators.as_slice() {
+        [Comparator {
+            op: ComparatorOp::Exact,
+            major,
+            minor: Some(minor),
+            patch: Some(patch),
+            pre,
+        }] => {
+            let version = SemVersion {
+                major: *major,
+                minor: *minor,
+                patch: *patch,
+                pre: pre.clone(),
+                build: Default::default(),
+            }
+            .to_compact_string();
+
+            if is_crate_yanked(&client, name, &version).await? {
+                return Err(BinstallError::VersionMismatch {
+                    req: version_req.clone(),
+                });
+            }
+
+            version
+        }
+        _ => fetch_crate_cratesio_version_matched(&client, name, version_req).await?,
+    };
+
     // Download crate to temporary dir (crates.io or git?)
     let crate_url = format!("https://crates.io/api/v1/crates/{name}/{version}/download");