feat: Preserve output base between restarts

This now uses a hash of the workspace directory as the output base when using a separate output base for queries, instead of a temp directory. This avoid recreating this expensive-to-create directory when restarting the language server.

Fixes #13.

BUILD

@@ -3,18 +3,19 @@ load("@rules_rust//rust:defs.bzl", "rust_binary", "rust_test")
 rust_binary(
     name = "bazel-lsp",
     srcs = glob(["src/**/*.rs"]),
+    compile_data = ["//src/builtin:builtin.pb"],
     deps = [
         "//src/builtin:builtin_proto_rust",
         "@crates//:anyhow",
         "@crates//:clap",
         "@crates//:either",
+        "@crates//:hex",
         "@crates//:lsp-types",
+        "@crates//:ring",
         "@crates//:starlark",
         "@crates//:starlark_lsp",
-        "@crates//:tempfile",
         "@crates//:thiserror",
     ],
-    compile_data = ["//src/builtin:builtin.pb"],
 )
 
 rust_test(

Cargo.toml

@@ -9,14 +9,15 @@ edition = "2021"
 anyhow = "1.0.79"
 clap = { version = "4.4.18", features = ["derive"] }
 either = "1.9.0"
+hex = "0.4.3"
 itertools = "0.12.0"
 lsp-types = "0.94.1"
 prost = "0.12.3"
 prost-types = "0.12.3"
 protoc-gen-prost = "0.2.3"
 protoc-gen-tonic = "0.3.0"
+ring = "0.17.7"
 starlark = { git = "https://github.com/facebookexperimental/starlark-rust.git", branch = "main" }
 starlark_lsp = { git = "https://github.com/facebookexperimental/starlark-rust.git", branch = "main" }
-tempfile = "3.9.0"
 thiserror = "1.0.56"
 tonic = "0.10.2"

src/client.rs

@@ -80,8 +80,7 @@ impl BazelClient for BazelCli {
     fn query(&self, workspace: &BazelWorkspace, query: &str) -> anyhow::Result<String> {
         let mut command = &mut Command::new(&self.bazel);
         if let Some(output_base) = &workspace.query_output_base {
-            eprintln!("Running bazel query in {}", output_base.path().display());
-            command = command.arg("--output_base").arg(output_base.path());
+            command = command.arg("--output_base").arg(output_base);
         }
         command = command.arg("query").arg(query);
         command = command.current_dir(&workspace.root);

src/main.rs

@@ -30,7 +30,8 @@ struct Args {
     /// The directory to put the query output bases in.
     ///
     /// This is ignored if `--no-distinct-output-base` is enabled.
-    /// By default this is the OS's temp directory.
+    /// By default this is the directory `bazel-lsp` in the OS's
+    /// temp directory.
     #[arg(long)]
     query_output_base: Option<PathBuf>,
 }
@@ -41,7 +42,7 @@ fn main() -> anyhow::Result<()> {
     let query_output_base = if args.no_distinct_output_base {
         None
     } else {
-        Some(args.query_output_base.unwrap_or_else(|| env::temp_dir()))
+        Some(args.query_output_base.unwrap_or_else(|| env::temp_dir().join("bazel-lsp")))
     };
 
     let ctx = BazelContext::new(

src/workspace.rs

@@ -1,18 +1,19 @@
 use std::{
     borrow::Cow,
     io,
+    os::unix::ffi::OsStrExt,
     path::{Path, PathBuf},
 };
 
-use tempfile::TempDir;
+use ring::digest;
 
 use crate::client::BazelInfo;
 
 pub struct BazelWorkspace {
     pub root: PathBuf,
     /// The output base to use for querying. This allows queries to not
     /// be blocked by concurrent builds.
-    pub query_output_base: Option<TempDir>,
+    pub query_output_base: Option<PathBuf>,
     pub workspace_name: Option<String>,
     pub external_output_base: PathBuf,
 }
@@ -34,7 +35,10 @@ impl BazelWorkspace {
                 }),
             external_output_base: PathBuf::from(info.output_base).join("external"),
             query_output_base: if let Some(output_base) = query_output_base {
-                Some(TempDir::with_prefix_in("bazel-lsp-", output_base)?)
+                let hash =
+                    digest::digest(&digest::SHA256, output_base.as_ref().as_os_str().as_bytes());
+                let hash_hex = hex::encode(&hash);
+                Some(output_base.as_ref().join(hash_hex))
             } else {
                 None
             },