Revive cache cleaning

The idea here is that, on CI, we only want to cache crates.io
dependencies, and not local crates. This keeps the size of the cache
low, and also improves performance, as network and moving files on
disk (on Windows) can be slow.

6 files changed, 98 insertions, 42 deletions

diff --git a/crates/rust-analyzer/tests/heavy_tests/main.rs b/crates/rust-analyzer/tests/rust-analyzer/main.rs
index 7370505f8..fa315ff8e 100644
--- a/crates/rust-analyzer/tests/heavy_tests/main.rs
+++ b/crates/rust-analyzer/tests/rust-analyzer/main.rs
@@ -1,3 +1,13 @@
+//! The most high-level integrated tests for rust-analyzer.
+//!
+//! This tests run a full LSP event loop, spawn cargo and process stdlib from
+//! sysroot. For this reason, the tests here are very slow, and should be
+//! avoided unless absolutely necessary.
+//!
+//! In particular, it's fine *not* to test that client & server agree on
+//! specific JSON shapes here -- there's little value in such tests, as we can't
+//! be sure without a real client anyway.
+
 mod testdir;
 mod support;
 
diff --git a/crates/rust-analyzer/tests/heavy_tests/support.rs b/crates/rust-analyzer/tests/rust-analyzer/support.rs
index 5bafeba79..5bafeba79 100644
--- a/crates/rust-analyzer/tests/heavy_tests/support.rs
+++ b/crates/rust-analyzer/tests/rust-analyzer/support.rs
diff --git a/crates/rust-analyzer/tests/heavy_tests/testdir.rs b/crates/rust-analyzer/tests/rust-analyzer/testdir.rs
index 7487e7429..7487e7429 100644
--- a/crates/rust-analyzer/tests/heavy_tests/testdir.rs
+++ b/crates/rust-analyzer/tests/rust-analyzer/testdir.rs
diff --git a/xtask/src/lib.rs b/xtask/src/lib.rs
index f3ad81ba7..e790d995f 100644
--- a/xtask/src/lib.rs
+++ b/xtask/src/lib.rs
@@ -3,14 +3,15 @@
 //! See https://github.com/matklad/cargo-xtask/
 
 pub mod not_bash;
+pub mod codegen;
+mod ast_src;
+
 pub mod install;
 pub mod release;
 pub mod dist;
 pub mod pre_commit;
 pub mod metrics;
-
-pub mod codegen;
-mod ast_src;
+pub mod pre_cache;
 
 use std::{
     env,
@@ -21,7 +22,7 @@ use walkdir::{DirEntry, WalkDir};
 
 use crate::{
     codegen::Mode,
-    not_bash::{fs2, pushd, pushenv, rm_rf},
+    not_bash::{pushd, pushenv},
 };
 
 pub use anyhow::{bail, Context as _, Result};
@@ -108,42 +109,6 @@ pub fn run_fuzzer() -> Result<()> {
     Ok(())
 }
 
-/// Cleans the `./target` dir after the build such that only
-/// dependencies are cached on CI.
-pub fn run_pre_cache() -> Result<()> {
-    let slow_tests_cookie = Path::new("./target/.slow_tests_cookie");
-    if !slow_tests_cookie.exists() {
-        panic!("slow tests were skipped on CI!")
-    }
-    rm_rf(slow_tests_cookie)?;
-
-    for entry in Path::new("./target/debug").read_dir()? {
-        let entry = entry?;
-        if entry.file_type().map(|it| it.is_file()).ok() == Some(true) {
-            // Can't delete yourself on windows :-(
-            if !entry.path().ends_with("xtask.exe") {
-                rm_rf(&entry.path())?
-            }
-        }
-    }
-
-    fs2::remove_file("./target/.rustc_info.json")?;
-    let to_delete = ["hir", "heavy_test", "xtask", "ide", "rust-analyzer"];
-    for &dir in ["./target/debug/deps", "target/debug/.fingerprint"].iter() {
-        for entry in Path::new(dir).read_dir()? {
-            let entry = entry?;
-            if to_delete.iter().any(|&it| entry.path().display().to_string().contains(it)) {
-                // Can't delete yourself on windows :-(
-                if !entry.path().ends_with("xtask.exe") {
-                    rm_rf(&entry.path())?
-                }
-            }
-        }
-    }
-
-    Ok(())
-}
-
 fn is_release_tag(tag: &str) -> bool {
     tag.len() == "2020-02-24".len() && tag.starts_with(|c: char| c.is_ascii_digit())
 }
diff --git a/xtask/src/main.rs b/xtask/src/main.rs
index b69b884e5..fb38fdc92 100644
--- a/xtask/src/main.rs
+++ b/xtask/src/main.rs
@@ -17,9 +17,10 @@ use xtask::{
     install::{ClientOpt, InstallCmd, Malloc, ServerOpt},
     metrics::MetricsCmd,
     not_bash::pushd,
+    pre_cache::PreCacheCmd,
     pre_commit, project_root,
     release::{PromoteCmd, ReleaseCmd},
-    run_clippy, run_fuzzer, run_pre_cache, run_rustfmt, Result,
+    run_clippy, run_fuzzer, run_rustfmt, Result,
 };
 
 fn main() -> Result<()> {
@@ -100,7 +101,7 @@ FLAGS:
         }
         "pre-cache" => {
             args.finish()?;
-            run_pre_cache()
+            PreCacheCmd.run()
         }
         "release" => {
             let dry_run = args.contains("--dry-run");
diff --git a/xtask/src/pre_cache.rs b/xtask/src/pre_cache.rs
new file mode 100644
index 000000000..47ba6ba24
--- /dev/null
+++ b/xtask/src/pre_cache.rs
@@ -0,0 +1,80 @@
+use std::{
+    fs::FileType,
+    path::{Path, PathBuf},
+};
+
+use anyhow::Result;
+
+use crate::not_bash::{fs2, rm_rf};
+
+pub struct PreCacheCmd;
+
+impl PreCacheCmd {
+    /// Cleans the `./target` dir after the build such that only
+    /// dependencies are cached on CI.
+    pub fn run(self) -> Result<()> {
+        let slow_tests_cookie = Path::new("./target/.slow_tests_cookie");
+        if !slow_tests_cookie.exists() {
+            panic!("slow tests were skipped on CI!")
+        }
+        rm_rf(slow_tests_cookie)?;
+
+        for path in read_dir("./target/debug", FileType::is_file)? {
+            // Can't delete yourself on windows :-(
+            if !path.ends_with("xtask.exe") {
+                rm_rf(&path)?
+            }
+        }
+
+        fs2::remove_file("./target/.rustc_info.json")?;
+
+        let to_delete = read_dir("./crates", FileType::is_dir)?
+            .into_iter()
+            .map(|path| path.file_name().unwrap().to_string_lossy().replace('-', "_"))
+            .collect::<Vec<_>>();
+
+        for &dir in ["./target/debug/deps", "target/debug/.fingerprint"].iter() {
+            for path in read_dir(dir, |_file_type| true)? {
+                if path.ends_with("xtask.exe") {
+                    continue;
+                }
+                let file_name = path.file_name().unwrap().to_string_lossy();
+                let (stem, _) = match rsplit_once(&file_name, '-') {
+                    Some(it) => it,
+                    None => {
+                        rm_rf(path)?;
+                        continue;
+                    }
+                };
+                let stem = stem.replace('-', "_");
+                if to_delete.contains(&stem) {
+                    rm_rf(path)?;
+                }
+            }
+        }
+
+        Ok(())
+    }
+}
+fn read_dir(path: impl AsRef<Path>, cond: impl Fn(&FileType) -> bool) -> Result<Vec<PathBuf>> {
+    read_dir_impl(path.as_ref(), &cond)
+}
+
+fn read_dir_impl(path: &Path, cond: &dyn Fn(&FileType) -> bool) -> Result<Vec<PathBuf>> {
+    let mut res = Vec::new();
+    for entry in path.read_dir()? {
+        let entry = entry?;
+        let file_type = entry.file_type()?;
+        if cond(&file_type) {
+            res.push(entry.path())
+        }
+    }
+    Ok(res)
+}
+
+fn rsplit_once(haystack: &str, delim: char) -> Option<(&str, &str)> {
+    let mut split = haystack.rsplitn(2, delim);
+    let suffix = split.next()?;
+    let prefix = split.next()?;
+    Some((prefix, suffix))
+}