working_copy: keep track of workspace ID (#13)

This patch makes it so the workspace ID can be stored in
`.jj/working_copy/checkout`. The workspace ID is still always
"default".

lib/protos/working_copy.proto

@@ -37,6 +37,11 @@ message TreeState {
 message Checkout {
   // The operation at which the working copy was updated.
   bytes operation_id = 2;
+  // An identifier for this workspace. It is used for looking up the current
+  // checkout in the repo view. Currently a human-readable name.
+  // TODO: Is it better to make this a UUID and a have map that to a name in
+  // config? That way users can rename a workspace.
+  string workspace_id = 3;
   // The checked-out commit, which can be viewed as a cache of the checkout
   // recorded in `operation_id`'s operation.
   bytes commit_id = 1;

lib/src/working_copy.rs

@@ -39,7 +39,7 @@ use crate::conflicts::{materialize_conflict, update_conflict_from_content};
 use crate::gitignore::GitIgnoreFile;
 use crate::lock::FileLock;
 use crate::matchers::EverythingMatcher;
-use crate::op_store::OperationId;
+use crate::op_store::{OperationId, WorkspaceId};
 use crate::repo_path::{RepoPath, RepoPathComponent, RepoPathJoin};
 use crate::store::Store;
 use crate::tree::{Diff, Tree};
@@ -719,6 +719,7 @@ pub struct WorkingCopy {
     working_copy_path: PathBuf,
     state_path: PathBuf,
     operation_id: RefCell<Option<OperationId>>,
+    workspace_id: RefCell<Option<WorkspaceId>>,
     commit_id: RefCell<Option<CommitId>>,
     tree_state: RefCell<Option<TreeState>>,
 }
@@ -734,6 +735,7 @@ impl WorkingCopy {
         working_copy_path: PathBuf,
         state_path: PathBuf,
         operation_id: OperationId,
+        workspace_id: WorkspaceId,
         commit_id: CommitId,
     ) -> WorkingCopy {
         let mut proto = crate::protos::working_copy::Checkout::new();
@@ -748,8 +750,9 @@ impl WorkingCopy {
             store,
             working_copy_path,
             state_path,
-            commit_id: RefCell::new(Some(commit_id)),
             operation_id: RefCell::new(Some(operation_id)),
+            workspace_id: RefCell::new(Some(workspace_id)),
+            commit_id: RefCell::new(Some(commit_id)),
             tree_state: RefCell::new(None),
         }
     }
@@ -760,6 +763,7 @@ impl WorkingCopy {
             working_copy_path,
             state_path,
             operation_id: RefCell::new(None),
+            workspace_id: RefCell::new(None),
             commit_id: RefCell::new(None),
             tree_state: RefCell::new(None),
         }
@@ -779,6 +783,14 @@ impl WorkingCopy {
             Message::parse_from_reader(&mut file).unwrap();
         self.operation_id
             .replace(Some(OperationId::new(proto.operation_id)));
+        let workspace_id = if proto.workspace_id.is_empty() {
+            // For compatibility with old working copies.
+            // TODO: Delete in mid 2022 or so
+            WorkspaceId::default()
+        } else {
+            WorkspaceId::new(proto.workspace_id)
+        };
+        self.workspace_id.replace(Some(workspace_id));
         self.commit_id.replace(Some(CommitId::new(proto.commit_id)));
     }
 
@@ -790,6 +802,14 @@ impl WorkingCopy {
         self.operation_id.borrow().as_ref().unwrap().clone()
     }
 
+    pub fn workspace_id(&self) -> WorkspaceId {
+        if self.workspace_id.borrow().is_none() {
+            self.load_proto();
+        }
+
+        self.workspace_id.borrow().as_ref().unwrap().clone()
+    }
+
     /// The id of the commit that's currently checked out in the working copy.
     /// Note that the View is the source of truth for which commit *should*
     /// be checked out. That should be kept up to date within a Transaction.
@@ -828,6 +848,7 @@ impl WorkingCopy {
     fn save(&mut self) {
         let mut proto = crate::protos::working_copy::Checkout::new();
         proto.operation_id = self.operation_id().to_bytes();
+        proto.workspace_id = self.workspace_id().as_str().to_string();
         proto.commit_id = self.current_commit_id().to_bytes();
         self.write_proto(proto);
     }

lib/src/workspace.rs

@@ -17,6 +17,7 @@ use std::sync::Arc;
 
 use thiserror::Error;
 
+use crate::op_store::WorkspaceId;
 use crate::repo::{ReadonlyRepo, RepoLoader};
 use crate::settings::UserSettings;
 use crate::working_copy::WorkingCopy;
@@ -60,11 +61,13 @@ fn init_working_copy(
 ) -> WorkingCopy {
     let working_copy_state_path = jj_dir.join("working_copy");
     std::fs::create_dir(&working_copy_state_path).unwrap();
+    let workspace_id = WorkspaceId::default();
     WorkingCopy::init(
         repo.store().clone(),
         workspace_root.to_path_buf(),
         working_copy_state_path,
         repo.op_id().clone(),
+        workspace_id,
         repo.view().checkout().clone(),
     )
 }
@@ -159,6 +162,10 @@ impl Workspace {
         &self.workspace_root
     }
 
+    pub fn workspace_id(&self) -> WorkspaceId {
+        self.working_copy.workspace_id()
+    }
+
     pub fn repo_path(&self) -> &PathBuf {
         self.repo_loader.repo_path()
     }