ci(windows): Introduce setup-dev-drive.ps1, maximize dev drive usage (#6858)

As suggested by @samypr100 on #6680:
https://github.com/astral-sh/uv/pull/6680#issuecomment-2313607984

## Summary

Instead of using `UV_INTERNAL__TEST_DIR`, it simply exports `TEMP` when
running Windows jobs.

## Test Plan

I'm going to run this manually under ProcMon on my Windows machine and
see where uv writes temp files, hopefully to the dev drive and not
`%(LOCAL)APPDATA%` or something.

I'm going to commit a dummy code change and look at build time changes
in CI.

.github/workflows/ci.yml

@@ -240,22 +240,15 @@ jobs:
       labels: "windows-latest-xlarge"
     name: "cargo test | windows"
     steps:
-      - name: Create Dev Drive using ReFS
-        run: |
-          $Volume = New-VHD -Path C:/uv_dev_drive.vhdx -SizeBytes 20GB |
-                    Mount-VHD -Passthru |
-                    Initialize-Disk -Passthru |
-                    New-Partition -AssignDriveLetter -UseMaximumSize |
-                    Format-Volume -FileSystem ReFS -Confirm:$false -Force
-          Write-Output $Volume
-          Write-Output "DEV_DRIVE=$($Volume.DriveLetter):" >> $env:GITHUB_ENV
-
       - uses: actions/checkout@v4
 
+      - name: Create Dev Drive using ReFS
+        run: ${{ github.workspace }}/.github/workflows/setup-dev-drive.ps1
+
       # actions/checkout does not let us clone into anywhere outside ${{ github.workspace }}, so we have to copy the clone...
       - name: Copy Git Repo to Dev Drive
         run: |
-          Copy-Item -Path "${{ github.workspace }}" -Destination "${{ env.DEV_DRIVE }}/uv" -Recurse
+          Copy-Item -Path "${{ github.workspace }}" -Destination "${{ env.UV_WORKSPACE }}" -Recurse
 
       # We do not test with Python patch versions on Windows
       # so we can use `setup-python` instead of our bootstrapping code
@@ -271,40 +264,25 @@ jobs:
 
       - uses: Swatinem/rust-cache@v2
         with:
-          workspaces: ${{ env.DEV_DRIVE }}/uv
-        env:
-          CARGO_HOME: ${{ env.DEV_DRIVE }}/.cargo
-          RUSTUP_HOME: ${{ env.DEV_DRIVE }}/.rustup
+          workspaces: ${{ env.UV_WORKSPACE }}
 
       - name: "Install Rust toolchain"
-        working-directory: ${{ env.DEV_DRIVE }}/uv
-        env:
-          CARGO_HOME: ${{ env.DEV_DRIVE }}/.cargo
-          RUSTUP_HOME: ${{ env.DEV_DRIVE }}/.rustup
+        working-directory: ${{ env.UV_WORKSPACE }}
         run: rustup show
 
       - name: "Install cargo nextest"
         uses: taiki-e/install-action@v2
         with:
           tool: cargo-nextest
-        env:
-          CARGO_HOME: ${{ env.DEV_DRIVE }}/.cargo
-          RUSTUP_HOME: ${{ env.DEV_DRIVE }}/.rustup
 
       - name: "Cargo test"
-        working-directory: ${{ env.DEV_DRIVE }}/uv
-        env:
-          CARGO_HOME: ${{ env.DEV_DRIVE }}/.cargo
-          RUSTUP_HOME: ${{ env.DEV_DRIVE }}/.rustup
-          UV_INTERNAL__TEST_DIR: ${{ env.DEV_DRIVE }}/tmp-uv
+        working-directory: ${{ env.UV_WORKSPACE }}
         run: |
           cargo nextest run --no-default-features --features python,pypi --workspace --status-level skip --failure-output immediate-final --no-fail-fast -j 20 --final-status-level slow
 
       - name: "Smoke test"
-        working-directory: ${{ env.DEV_DRIVE }}/uv
+        working-directory: ${{ env.UV_WORKSPACE }}
         env:
-          CARGO_HOME: ${{ env.DEV_DRIVE }}/.cargo
-          RUSTUP_HOME: ${{ env.DEV_DRIVE }}/.rustup
           # Avoid debug build stack overflows.
           UV_STACK_SIZE: 2000000 # 2 megabyte, double the default on windows
         run: |
@@ -518,44 +496,29 @@ jobs:
       labels: windows-latest-large
     name: "build binary | windows"
     steps:
-      - name: Create Dev Drive using ReFS
-        run: |
-          $Volume = New-VHD -Path C:/uv_dev_drive.vhdx -SizeBytes 10GB |
-                    Mount-VHD -Passthru |
-                    Initialize-Disk -Passthru |
-                    New-Partition -AssignDriveLetter -UseMaximumSize |
-                    Format-Volume -FileSystem ReFS -Confirm:$false -Force
-          Write-Output $Volume
-          Write-Output "DEV_DRIVE=$($Volume.DriveLetter):" >> $env:GITHUB_ENV
-
       - uses: actions/checkout@v4
 
+      - name: Create Dev Drive using ReFS
+        run: ${{ github.workspace }}/.github/workflows/setup-dev-drive.ps1
+
       # actions/checkout does not let us clone into anywhere outside ${{ github.workspace }}, so we have to copy the clone...
       - name: Copy Git Repo to Dev Drive
         run: |
-          Copy-Item -Path "${{ github.workspace }}" -Destination "${{ env.DEV_DRIVE }}/uv" -Recurse
-
-      - uses: rui314/setup-mold@v1
+          Copy-Item -Path "${{ github.workspace }}" -Destination "${{ env.UV_WORKSPACE }}" -Recurse
 
       - uses: Swatinem/rust-cache@v2
         with:
-          workspaces: ${{ env.DEV_DRIVE }}/uv
-        env:
-          CARGO_HOME: ${{ env.DEV_DRIVE }}/.cargo
-          RUSTUP_HOME: ${{ env.DEV_DRIVE }}/.rustup
+          workspaces: ${{ env.UV_WORKSPACE }}
 
       - name: "Build"
-        working-directory: ${{ env.DEV_DRIVE }}/uv
-        env:
-          CARGO_HOME: ${{ env.DEV_DRIVE }}/.cargo
-          RUSTUP_HOME: ${{ env.DEV_DRIVE }}/.rustup
+        working-directory: ${{ env.UV_WORKSPACE }}
         run: cargo build
 
       - name: "Upload binary"
         uses: actions/upload-artifact@v4
         with:
           name: uv-windows-${{ github.sha }}
-          path: ${{ env.DEV_DRIVE }}/uv/target/debug/uv.exe
+          path: ${{ env.UV_WORKSPACE }}/target/debug/uv.exe
           retention-days: 1
 
   ecosystem-test:

.github/workflows/setup-dev-drive.ps1

@@ -0,0 +1,24 @@
+# This creates a 20GB dev drive, and exports all required environment
+# variables so that rustup, uv and others all use the dev drive as much
+# as possible.
+$Volume = New-VHD -Path C:/uv_dev_drive.vhdx -SizeBytes 20GB |
+					Mount-VHD -Passthru |
+					Initialize-Disk -Passthru |
+					New-Partition -AssignDriveLetter -UseMaximumSize |
+					Format-Volume -FileSystem ReFS -Confirm:$false -Force
+
+Write-Output $Volume
+
+$Drive = "$($Volume.DriveLetter):"
+$Tmp = "$($Drive)/uv-tmp"
+
+Write-Output `
+	"DEV_DRIVE=$($Drive)" `
+	"TMP=$($Tmp)" `
+	"TEMP=$($Tmp)" `
+	"UV_INTERNAL__TEST_DIR=$($Tmp)" `
+	"RUSTUP_HOME=$($Drive)/.rustup" `
+	"CARGO_HOME=$($Drive)/.cargo" `
+	"UV_WORKSPACE=$($Drive)/uv" `
+	>> $env:GITHUB_ENV
+

crates/distribution-types/src/installed.rs

@@ -90,6 +90,7 @@ impl InstalledDist {
 
             let name = PackageName::from_str(name)?;
             let version = Version::from_str(version).map_err(|err| anyhow!(err))?;
+
             return if let Some(direct_url) = Self::direct_url(path)? {
                 match Url::try_from(&direct_url) {
                     Ok(url) => Ok(Some(Self::Url(InstalledDirectUrlDist {

crates/uv-cache/src/lib.rs

@@ -135,14 +135,7 @@ impl Cache {
 
     /// Create a temporary cache directory.
     pub fn temp() -> Result<Self, io::Error> {
-        let temp_dir =
-            if let Ok(test_dir) = std::env::var("UV_INTERNAL__TEST_DIR").map(PathBuf::from) {
-                let uv_cache_dir = test_dir.join("uv-cache");
-                let _ = fs_err::create_dir_all(&uv_cache_dir);
-                tempfile::tempdir_in(uv_cache_dir)?
-            } else {
-                tempfile::tempdir()?
-            };
+        let temp_dir = tempfile::tempdir()?;
         Ok(Self {
             root: temp_dir.path().to_path_buf(),
             refresh: Refresh::None(Timestamp::now()),