add analysis-bench to benchmark incremental analysis

Can be used like this:

```
$ cargo run --release -p ra_cli -- \
  analysis-bench ../chalk/ \
  --complete ../chalk/chalk-engine/src/logic.rs:94:0

loading: 225.970093ms

from scratch:   8.492373325s
no change:      445.265µs
trivial change: 95.631242ms
```

Or like this:

```
$ cargo run --release -p ra_cli -- \
  analysis-bench ../chalk/ \
  --highlight ../chalk/chalk-engine/src/logic.rs

loading: 209.873484ms

from scratch:   9.504916942s
no change:      7.731119ms
trivial change: 124.984039ms
```

"from scratch" includes initial analysis of the relevant bits of the
project

"no change" just asks the same question for the second time. It
measures overhead on assembling the answer outside of salsa.

"trivial change" doesn't do an actual salsa change, it just advances
the revision. This test how fast is salsa at validating things.

2 files changed, 79 insertions, 71 deletions

diff --git a/crates/ra_batch/src/lib.rs b/crates/ra_batch/src/lib.rs
index fa244e86c..43d3fb7e3 100644
--- a/crates/ra_batch/src/lib.rs
+++ b/crates/ra_batch/src/lib.rs
@@ -8,7 +8,7 @@ use ra_db::{
     CrateGraph, FileId, SourceRootId,
 };
 use ra_ide_api::{AnalysisHost, AnalysisChange};
-use ra_project_model::ProjectWorkspace;
+use ra_project_model::{ProjectWorkspace, ProjectRoot};
 use ra_vfs::{Vfs, VfsChange};
 use vfs_filter::IncludeRustFiles;
 
@@ -21,13 +21,11 @@ fn vfs_root_to_id(r: ra_vfs::VfsRoot) -> SourceRootId {
     SourceRootId(r.0)
 }
 
-pub fn load_cargo(root: &Path) -> Result<(AnalysisHost, Vec<SourceRootId>)> {
+pub fn load_cargo(root: &Path) -> Result<(AnalysisHost, FxHashMap<SourceRootId, ProjectRoot>)> {
     let root = std::env::current_dir()?.join(root);
     let ws = ProjectWorkspace::discover(root.as_ref())?;
-    let mut roots = Vec::new();
-    roots.push(IncludeRustFiles::member(root.clone()));
-    roots.extend(IncludeRustFiles::from_roots(ws.to_roots()));
-    let (mut vfs, roots) = Vfs::new(roots);
+    let project_roots = ws.to_roots();
+    let (mut vfs, roots) = Vfs::new(IncludeRustFiles::from_roots(project_roots.clone()).collect());
     let crate_graph = ws.to_crate_graph(&mut |path: &Path| {
         let vfs_file = vfs.load(path);
         log::debug!("vfs file {:?} -> {:?}", path, vfs_file);
@@ -35,17 +33,27 @@ pub fn load_cargo(root: &Path) -> Result<(AnalysisHost, Vec<SourceRootId>)> {
     });
     log::debug!("crate graph: {:?}", crate_graph);
 
-    let local_roots = roots
-        .into_iter()
-        .filter(|r| vfs.root2path(*r).starts_with(&root))
-        .map(vfs_root_to_id)
-        .collect();
-
-    let host = load(root.as_path(), crate_graph, &mut vfs);
-    Ok((host, local_roots))
+    let source_roots = roots
+        .iter()
+        .map(|&vfs_root| {
+            let source_root_id = vfs_root_to_id(vfs_root);
+            let project_root = project_roots
+                .iter()
+                .find(|it| it.path() == &vfs.root2path(vfs_root))
+                .unwrap()
+                .clone();
+            (source_root_id, project_root)
+        })
+        .collect::<FxHashMap<_, _>>();
+    let host = load(&source_roots, crate_graph, &mut vfs);
+    Ok((host, source_roots))
 }
 
-pub fn load(project_root: &Path, crate_graph: CrateGraph, vfs: &mut Vfs) -> AnalysisHost {
+pub fn load(
+    source_roots: &FxHashMap<SourceRootId, ProjectRoot>,
+    crate_graph: CrateGraph,
+    vfs: &mut Vfs,
+) -> AnalysisHost {
     let lru_cap = std::env::var("RA_LRU_CAP").ok().and_then(|it| it.parse::<usize>().ok());
     let mut host = AnalysisHost::new(lru_cap);
     let mut analysis_change = AnalysisChange::new();
@@ -60,8 +68,8 @@ pub fn load(project_root: &Path, crate_graph: CrateGraph, vfs: &mut Vfs) -> Anal
         for change in vfs.commit_changes() {
             match change {
                 VfsChange::AddRoot { root, files } => {
-                    let is_local = vfs.root2path(root).starts_with(&project_root);
                     let source_root_id = vfs_root_to_id(root);
+                    let is_local = source_roots[&source_root_id].is_member();
                     log::debug!(
                         "loaded source root {:?} with path {:?}",
                         source_root_id,
@@ -106,7 +114,7 @@ mod tests {
         let path = Path::new(env!("CARGO_MANIFEST_DIR")).parent().unwrap().parent().unwrap();
         let (host, roots) = load_cargo(path).unwrap();
         let mut n_crates = 0;
-        for root in roots {
+        for (root, _) in roots {
             for _krate in Crate::source_root_crates(host.raw_database(), root) {
                 n_crates += 1;
             }
diff --git a/crates/ra_batch/src/vfs_filter.rs b/crates/ra_batch/src/vfs_filter.rs
index dd20c1203..8552ac999 100644
--- a/crates/ra_batch/src/vfs_filter.rs
+++ b/crates/ra_batch/src/vfs_filter.rs
@@ -1,54 +1,54 @@
-use std::path::PathBuf;

-use ra_project_model::ProjectRoot;

-use ra_vfs::{RootEntry, Filter, RelativePath};

-

-/// `IncludeRustFiles` is used to convert

-/// from `ProjectRoot` to `RootEntry` for VFS

-pub struct IncludeRustFiles {

-    root: ProjectRoot,

-}

-

-impl IncludeRustFiles {

-    pub fn from_roots<R>(roots: R) -> impl Iterator<Item = RootEntry>

-    where

-        R: IntoIterator<Item = ProjectRoot>,

-    {

-        roots.into_iter().map(IncludeRustFiles::from_root)

-    }

-

-    pub fn from_root(root: ProjectRoot) -> RootEntry {

-        IncludeRustFiles::from(root).into()

-    }

-

-    #[allow(unused)]

-    pub fn external(path: PathBuf) -> RootEntry {

-        IncludeRustFiles::from_root(ProjectRoot::new(path, false))

-    }

-

-    pub fn member(path: PathBuf) -> RootEntry {

-        IncludeRustFiles::from_root(ProjectRoot::new(path, true))

-    }

-}

-

-impl Filter for IncludeRustFiles {

-    fn include_dir(&self, dir_path: &RelativePath) -> bool {

-        self.root.include_dir(dir_path)

-    }

-

-    fn include_file(&self, file_path: &RelativePath) -> bool {

-        self.root.include_file(file_path)

-    }

-}

-

-impl std::convert::From<ProjectRoot> for IncludeRustFiles {

-    fn from(v: ProjectRoot) -> IncludeRustFiles {

-        IncludeRustFiles { root: v }

-    }

-}

-

-impl std::convert::From<IncludeRustFiles> for RootEntry {

-    fn from(v: IncludeRustFiles) -> RootEntry {

-        let path = v.root.path().clone();

-        RootEntry::new(path, Box::new(v))

-    }

-}

+use std::path::PathBuf;
+use ra_project_model::ProjectRoot;
+use ra_vfs::{RootEntry, Filter, RelativePath};
+
+/// `IncludeRustFiles` is used to convert
+/// from `ProjectRoot` to `RootEntry` for VFS
+pub struct IncludeRustFiles {
+    root: ProjectRoot,
+}
+
+impl IncludeRustFiles {
+    pub fn from_roots<R>(roots: R) -> impl Iterator<Item = RootEntry>
+    where
+        R: IntoIterator<Item = ProjectRoot>,
+    {
+        roots.into_iter().map(IncludeRustFiles::from_root)
+    }
+
+    pub fn from_root(root: ProjectRoot) -> RootEntry {
+        IncludeRustFiles::from(root).into()
+    }
+
+    #[allow(unused)]
+    pub fn external(path: PathBuf) -> RootEntry {
+        IncludeRustFiles::from_root(ProjectRoot::new(path, false))
+    }
+
+    pub fn member(path: PathBuf) -> RootEntry {
+        IncludeRustFiles::from_root(ProjectRoot::new(path, true))
+    }
+}
+
+impl Filter for IncludeRustFiles {
+    fn include_dir(&self, dir_path: &RelativePath) -> bool {
+        self.root.include_dir(dir_path)
+    }
+
+    fn include_file(&self, file_path: &RelativePath) -> bool {
+        self.root.include_file(file_path)
+    }
+}
+
+impl From<ProjectRoot> for IncludeRustFiles {
+    fn from(v: ProjectRoot) -> IncludeRustFiles {
+        IncludeRustFiles { root: v }
+    }
+}
+
+impl From<IncludeRustFiles> for RootEntry {
+    fn from(v: IncludeRustFiles) -> RootEntry {
+        let path = v.root.path().clone();
+        RootEntry::new(path, Box::new(v))
+    }
+}