Replace dashmap with papaya. (#4481)

## Motivation

`dashmap` can cause deadlocks if guards are held across `await` points,
but the compiler does not warn about it.

## Proposal

Use the lock-free `papaya` instead.

(The first commit was mostly written by Claude, the rest by me.)

## Test Plan

CI (no new functionality)

## Release Plan

- Nothing to do / These changes follow the usual release cycle.
- (But could be backported.)

## Links

- Closes #4139.
- [reviewer
checklist](https://github.com/linera-io/linera-protocol/blob/main/CONTRIBUTING.md#reviewer-checklist)

Author: afck

Cargo.lock

@@ -105,7 +105,6 @@ console_error_panic_hook = "0.1.7"
 convert_case = "0.6.0"
 criterion = { version = "0.5.1", default-features = false }
 custom_debug_derive = "0.6.1"
-dashmap = "5.5.3"
 deluxe = "0.5.0"
 derive_more = "1.0.0"
 dirs = "5.0.1"
@@ -156,6 +155,7 @@ num-format = "0.4.4"
 num-traits = "0.2.18"
 octocrab = "0.42.1"
 oneshot = "0.1.6"
+papaya = "0.1.5"
 pathdiff = "0.2.1"
 port-selector = "0.1.6"
 prettyplease = "0.2.16"

Cargo.toml

@@ -268,12 +268,11 @@ async fn test_application_permissions() -> anyhow::Result<()> {
     let mut chain = ChainStateView::new(chain_id).await;
 
     let extra = &chain.context().extra();
-    extra
-        .user_contracts()
-        .insert(application_id, application.clone().into());
-    extra
-        .user_contracts()
-        .insert(another_app_id, application.clone().into());
+    {
+        let pinned = extra.user_contracts().pin();
+        pinned.insert(application_id, application.clone().into());
+        pinned.insert(another_app_id, application.clone().into());
+    }
 
     extra
         .add_blobs([committee_blob(Default::default())])
@@ -723,12 +722,14 @@ async fn prepare_test_with_dummy_mock_application(
     let application_id = ApplicationId::from(&app_description);
     let application = MockApplication::default();
     let extra = &chain.context().extra();
-    extra
-        .user_contracts()
-        .insert(application_id, application.clone().into());
-    extra
-        .user_services()
-        .insert(application_id, application.clone().into());
+    {
+        let pinned = extra.user_contracts().pin();
+        pinned.insert(application_id, application.clone().into());
+    }
+    {
+        let pinned = extra.user_services().pin();
+        pinned.insert(application_id, application.clone().into());
+    }
     extra
         .add_blobs([
             committee_blob,

examples/Cargo.lock

@@ -56,7 +56,6 @@ bcs.workspace = true
 cfg-if.workspace = true
 clap.workspace = true
 custom_debug_derive.workspace = true
-dashmap.workspace = true
 futures.workspace = true
 linera-base.workspace = true
 linera-chain.workspace = true
@@ -65,6 +64,7 @@ linera-storage.workspace = true
 linera-version.workspace = true
 linera-views.workspace = true
 lru.workspace = true
+papaya.workspace = true
 prometheus = { workspace = true, optional = true }
 proptest = { workspace = true, optional = true }
 rand = { workspace = true, features = ["std_rng"] }

linera-chain/src/unit_tests/chain_tests.rs

@@ -32,6 +32,15 @@ impl ChainClientState {
         }
     }
 
+    /// Clones the state. This must only be used to update the state, and one of the two clones
+    /// must be dropped.
+    pub(super) fn clone_for_update_unchecked(&self) -> ChainClientState {
+        ChainClientState {
+            pending_proposal: self.pending_proposal.clone(),
+            client_mutex: Arc::clone(&self.client_mutex),
+        }
+    }
+
     pub fn pending_proposal(&self) -> &Option<PendingProposal> {
         &self.pending_proposal
     }