From d30adb21f27bb0f0d769829981c5744ce0b7e8f7 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Philipp=20Kr=C3=BCger?= <philipp.krueger1@gmail.com>
Date: Wed, 20 Mar 2024 09:59:09 +0100
Subject: [PATCH 1/7] refactor: Make delegation::Store::get return Option

---
 src/delegation/agent.rs        |  2 +-
 src/delegation/store/memory.rs | 16 ++++++++++------
 src/delegation/store/traits.rs |  9 ++++++---
 src/invocation/agent.rs        |  8 ++++++--
 4 files changed, 23 insertions(+), 12 deletions(-)

diff --git a/src/delegation/agent.rs b/src/delegation/agent.rs
index 89f86a8b..886b331b 100644
--- a/src/delegation/agent.rs
+++ b/src/delegation/agent.rs
@@ -14,7 +14,7 @@ use std::{collections::BTreeMap, marker::PhantomData};
 use thiserror::Error;
 use web_time::SystemTime;
 
-/// A stateful agent capable of delegatint to others, and being delegated to.
+/// A stateful agent capable of delegating to others, and being delegated to.
 ///
 /// This is helpful for sessions where more than one delegation will be made.
 #[derive(Debug)]
diff --git a/src/delegation/store/memory.rs b/src/delegation/store/memory.rs
index 18d86103..297715e2 100644
--- a/src/delegation/store/memory.rs
+++ b/src/delegation/store/memory.rs
@@ -10,7 +10,10 @@ use libipld_core::codec::Encode;
 use libipld_core::ipld::Ipld;
 use libipld_core::{cid::Cid, codec::Codec};
 use nonempty::NonEmpty;
-use std::collections::{BTreeMap, BTreeSet};
+use std::{
+    collections::{BTreeMap, BTreeSet},
+    convert::Infallible,
+};
 use web_time::SystemTime;
 
 #[cfg_attr(doc, aquamarine::aquamarine)]
@@ -117,12 +120,13 @@ where
     delegation::Payload<DID>: TryFrom<Named<Ipld>>,
     Delegation<DID, V, Enc>: Encode<Enc>,
 {
-    type DelegationStoreError = String; // FIXME misisng
+    type DelegationStoreError = Infallible;
 
-    fn get(&self, cid: &Cid) -> Result<&Delegation<DID, V, Enc>, Self::DelegationStoreError> {
-        self.ucans
-            .get(cid)
-            .ok_or(format!("not found in delegation memstore: {:?}", cid).into())
+    fn get(
+        &self,
+        cid: &Cid,
+    ) -> Result<Option<&Delegation<DID, V, Enc>>, Self::DelegationStoreError> {
+        Ok(self.ucans.get(cid))
         // FIXME
     }
 
diff --git a/src/delegation/store/traits.rs b/src/delegation/store/traits.rs
index 3bd7b1fb..2f8f42d5 100644
--- a/src/delegation/store/traits.rs
+++ b/src/delegation/store/traits.rs
@@ -11,7 +11,10 @@ use web_time::SystemTime;
 pub trait Store<DID: Did, V: varsig::Header<Enc>, Enc: Codec + TryFrom<u64> + Into<u64>> {
     type DelegationStoreError: Debug;
 
-    fn get(&self, cid: &Cid) -> Result<&Delegation<DID, V, Enc>, Self::DelegationStoreError>;
+    fn get(
+        &self,
+        cid: &Cid,
+    ) -> Result<Option<&Delegation<DID, V, Enc>>, Self::DelegationStoreError>;
 
     fn insert(
         &mut self,
@@ -60,7 +63,7 @@ pub trait Store<DID: Did, V: varsig::Header<Enc>, Enc: Codec + TryFrom<u64> + In
     fn get_many(
         &self,
         cids: &[Cid],
-    ) -> Result<Vec<&Delegation<DID, V, Enc>>, Self::DelegationStoreError> {
+    ) -> Result<Vec<Option<&Delegation<DID, V, Enc>>>, Self::DelegationStoreError> {
         cids.iter().try_fold(vec![], |mut acc, cid| {
             acc.push(self.get(cid)?);
             Ok(acc)
@@ -73,7 +76,7 @@ impl<T: Store<DID, V, C>, DID: Did, V: varsig::Header<C>, C: Codec + TryFrom<u64
 {
     type DelegationStoreError = <T as Store<DID, V, C>>::DelegationStoreError;
 
-    fn get(&self, cid: &Cid) -> Result<&Delegation<DID, V, C>, Self::DelegationStoreError> {
+    fn get(&self, cid: &Cid) -> Result<Option<&Delegation<DID, V, C>>, Self::DelegationStoreError> {
         (**self).get(cid)
     }
 
diff --git a/src/invocation/agent.rs b/src/invocation/agent.rs
index a4e5f7fd..c93e8036 100644
--- a/src/invocation/agent.rs
+++ b/src/invocation/agent.rs
@@ -209,8 +209,9 @@ where
             .get_many(&invocation.proofs())
             .map_err(ReceiveError::DelegationStoreError)?
             .iter()
-            .map(|d| &d.payload)
-            .collect();
+            .zip(invocation.proofs().iter())
+            .map(|(d, cid)| Ok(&d.ok_or(ReceiveError::MissingDelegation(*cid))?.payload))
+            .collect::<Result<_, ReceiveError<T, DID, D::DelegationStoreError, S, V, C>>>()?;
 
         let _ = &invocation
             .payload
@@ -290,6 +291,9 @@ pub enum ReceiveError<
 > where
     <S as Store<T, DID, V, C>>::InvocationStoreError: fmt::Debug,
 {
+    #[error("missing delegation: {0}")]
+    MissingDelegation(Cid),
+
     #[error("encoding error: {0}")]
     EncodingError(#[from] libipld_core::error::Error),
 

From 11c8c0508440d8cf0195ce1c70d21b63ea82a455 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Philipp=20Kr=C3=BCger?= <philipp.krueger1@gmail.com>
Date: Wed, 20 Mar 2024 11:57:01 +0100
Subject: [PATCH 2/7] refactor: Make delegation::Store::insert take &self
 instead of &mut self

---
 src/delegation/agent.rs        |  8 ++--
 src/delegation/store/memory.rs | 88 ++++++++++++++++++++++++++--------
 src/delegation/store/traits.rs | 33 +++++++------
 src/invocation/agent.rs        | 21 +++++---
 4 files changed, 103 insertions(+), 47 deletions(-)

diff --git a/src/delegation/agent.rs b/src/delegation/agent.rs
index 886b331b..f7b973d6 100644
--- a/src/delegation/agent.rs
+++ b/src/delegation/agent.rs
@@ -93,14 +93,12 @@ where
             }
         }
 
-        let to_delegate = &self
+        let proofs = &self
             .store
             .get_chain(&self.did, &subject, "/".into(), vec![], now)
             .map_err(DelegateError::StoreError)?
-            .ok_or(DelegateError::ProofsNotFound)?
-            .first()
-            .1
-            .payload();
+            .ok_or(DelegateError::ProofsNotFound)?;
+        let to_delegate = proofs.first().1.payload();
 
         let mut policy = to_delegate.policy.clone();
         policy.append(&mut new_policy.clone());
diff --git a/src/delegation/store/memory.rs b/src/delegation/store/memory.rs
index 297715e2..c36a6e2d 100644
--- a/src/delegation/store/memory.rs
+++ b/src/delegation/store/memory.rs
@@ -10,6 +10,7 @@ use libipld_core::codec::Encode;
 use libipld_core::ipld::Ipld;
 use libipld_core::{cid::Cid, codec::Codec};
 use nonempty::NonEmpty;
+use std::sync::{Arc, Mutex, RwLock, RwLockReadGuard, RwLockWriteGuard};
 use std::{
     collections::{BTreeMap, BTreeSet},
     convert::Infallible,
@@ -72,36 +73,77 @@ use web_time::SystemTime;
 /// linkStyle 6 stroke:orange;
 /// linkStyle 1 stroke:orange;
 /// ```
-#[derive(Debug, Clone, PartialEq)]
+#[derive(Debug, Clone)]
 pub struct MemoryStore<
     DID: did::Did + Ord = did::preset::Verifier,
     V: varsig::Header<C> = varsig::header::Preset,
     C: Codec + TryFrom<u64> + Into<u64> = varsig::encoding::Preset,
 > {
-    ucans: BTreeMap<Cid, Delegation<DID, V, C>>,
+    inner: Arc<RwLock<MemoryStoreInner<DID, V, C>>>,
+}
+
+#[derive(Debug, Clone, PartialEq)]
+struct MemoryStoreInner<
+    DID: did::Did + Ord = did::preset::Verifier,
+    V: varsig::Header<C> = varsig::header::Preset,
+    C: Codec + TryFrom<u64> + Into<u64> = varsig::encoding::Preset,
+> {
+    ucans: BTreeMap<Cid, Arc<Delegation<DID, V, C>>>,
     index: BTreeMap<Option<DID>, BTreeMap<DID, BTreeSet<Cid>>>,
     revocations: BTreeSet<Cid>,
 }
 
-impl MemoryStore {
+impl<DID: did::Did + Ord, V: varsig::Header<C>, C: Codec + TryFrom<u64> + Into<u64>>
+    MemoryStore<DID, V, C>
+{
     pub fn new() -> Self {
         Self::default()
     }
 
     pub fn len(&self) -> usize {
-        self.ucans.len()
+        self.read().ucans.len()
     }
 
     pub fn is_empty(&self) -> bool {
-        self.ucans.is_empty() // FIXME acocunt for revocations?
+        self.read().ucans.is_empty() // FIXME acocunt for revocations?
+    }
+
+    fn read(&self) -> RwLockReadGuard<'_, MemoryStoreInner<DID, V, C>> {
+        match self.inner.read() {
+            Ok(guard) => guard,
+            Err(poison) => {
+                // We ignore lock poisoning for simplicity
+                poison.into_inner()
+            }
+        }
+    }
+
+    fn write(&self) -> RwLockWriteGuard<'_, MemoryStoreInner<DID, V, C>> {
+        match self.inner.write() {
+            Ok(guard) => guard,
+            Err(poison) => {
+                // We ignore lock poisoning for simplicity
+                poison.into_inner()
+            }
+        }
     }
 }
 
-impl<DID: Did + Ord, V: varsig::Header<C>, C: Codec + TryFrom<u64> + Into<u64>> Default
+impl<DID: did::Did + Ord, V: varsig::Header<C>, C: Codec + TryFrom<u64> + Into<u64>> Default
     for MemoryStore<DID, V, C>
 {
     fn default() -> Self {
-        MemoryStore {
+        Self {
+            inner: Default::default(),
+        }
+    }
+}
+
+impl<DID: Did + Ord, V: varsig::Header<C>, C: Codec + TryFrom<u64> + Into<u64>> Default
+    for MemoryStoreInner<DID, V, C>
+{
+    fn default() -> Self {
+        MemoryStoreInner {
             ucans: BTreeMap::new(),
             index: BTreeMap::new(),
             revocations: BTreeSet::new(),
@@ -125,30 +167,34 @@ where
     fn get(
         &self,
         cid: &Cid,
-    ) -> Result<Option<&Delegation<DID, V, Enc>>, Self::DelegationStoreError> {
-        Ok(self.ucans.get(cid))
+    ) -> Result<Option<Arc<Delegation<DID, V, Enc>>>, Self::DelegationStoreError> {
+        // cheap Arc clone
+        Ok(self.read().ucans.get(cid).cloned())
         // FIXME
     }
 
     fn insert(
-        &mut self,
+        &self,
         cid: Cid,
         delegation: Delegation<DID, V, Enc>,
     ) -> Result<(), Self::DelegationStoreError> {
-        self.index
+        let mut write_tx = self.write();
+
+        write_tx
+            .index
             .entry(delegation.subject().clone())
             .or_default()
             .entry(delegation.audience().clone())
             .or_default()
             .insert(cid);
 
-        self.ucans.insert(cid.clone(), delegation);
+        write_tx.ucans.insert(cid.clone(), Arc::new(delegation));
 
         Ok(())
     }
 
-    fn revoke(&mut self, cid: Cid) -> Result<(), Self::DelegationStoreError> {
-        self.revocations.insert(cid);
+    fn revoke(&self, cid: Cid) -> Result<(), Self::DelegationStoreError> {
+        self.write().revocations.insert(cid);
         Ok(())
     }
 
@@ -159,12 +205,14 @@ where
         command: String,
         policy: Vec<Predicate>, // FIXME
         now: SystemTime,
-    ) -> Result<Option<NonEmpty<(Cid, &Delegation<DID, V, Enc>)>>, Self::DelegationStoreError> {
+    ) -> Result<Option<NonEmpty<(Cid, Arc<Delegation<DID, V, Enc>>)>>, Self::DelegationStoreError>
+    {
         let blank_set = BTreeSet::new();
         let blank_map = BTreeMap::new();
+        let read_tx = self.read();
 
-        let all_powerlines = self.index.get(&None).unwrap_or(&blank_map);
-        let all_aud_for_subject = self.index.get(subject).unwrap_or(&blank_map);
+        let all_powerlines = read_tx.index.get(&None).unwrap_or(&blank_map);
+        let all_aud_for_subject = read_tx.index.get(subject).unwrap_or(&blank_map);
         let powerline_candidates = all_powerlines.get(aud).unwrap_or(&blank_set);
         let sub_candidates = all_aud_for_subject.get(aud).unwrap_or(&blank_set);
 
@@ -189,11 +237,11 @@ where
                 }
 
                 'inner: for cid in parent_cid_candidates {
-                    if self.revocations.contains(cid) {
+                    if read_tx.revocations.contains(cid) {
                         continue;
                     }
 
-                    if let Some(delegation) = self.ucans.get(cid) {
+                    if let Some(delegation) = read_tx.ucans.get(cid) {
                         if delegation.check_time(now).is_err() {
                             continue;
                         }
@@ -221,7 +269,7 @@ where
                             }
                         }
 
-                        hypothesis_chain.push((cid.clone(), delegation));
+                        hypothesis_chain.push((cid.clone(), Arc::clone(delegation)));
 
                         let issuer = delegation.issuer().clone();
 
diff --git a/src/delegation/store/traits.rs b/src/delegation/store/traits.rs
index 2f8f42d5..7413e700 100644
--- a/src/delegation/store/traits.rs
+++ b/src/delegation/store/traits.rs
@@ -5,7 +5,7 @@ use crate::{
 };
 use libipld_core::{cid::Cid, codec::Codec};
 use nonempty::NonEmpty;
-use std::fmt::Debug;
+use std::{fmt::Debug, sync::Arc};
 use web_time::SystemTime;
 
 pub trait Store<DID: Did, V: varsig::Header<Enc>, Enc: Codec + TryFrom<u64> + Into<u64>> {
@@ -14,10 +14,10 @@ pub trait Store<DID: Did, V: varsig::Header<Enc>, Enc: Codec + TryFrom<u64> + In
     fn get(
         &self,
         cid: &Cid,
-    ) -> Result<Option<&Delegation<DID, V, Enc>>, Self::DelegationStoreError>;
+    ) -> Result<Option<Arc<Delegation<DID, V, Enc>>>, Self::DelegationStoreError>;
 
     fn insert(
-        &mut self,
+        &self,
         cid: Cid,
         delegation: Delegation<DID, V, Enc>,
     ) -> Result<(), Self::DelegationStoreError>;
@@ -25,7 +25,7 @@ pub trait Store<DID: Did, V: varsig::Header<Enc>, Enc: Codec + TryFrom<u64> + In
     // FIXME validate invocation
     // store invocation
     // just... move to invocation
-    fn revoke(&mut self, cid: Cid) -> Result<(), Self::DelegationStoreError>;
+    fn revoke(&self, cid: Cid) -> Result<(), Self::DelegationStoreError>;
 
     fn get_chain(
         &self,
@@ -34,7 +34,7 @@ pub trait Store<DID: Did, V: varsig::Header<Enc>, Enc: Codec + TryFrom<u64> + In
         command: String,
         policy: Vec<Predicate>,
         now: SystemTime,
-    ) -> Result<Option<NonEmpty<(Cid, &Delegation<DID, V, Enc>)>>, Self::DelegationStoreError>;
+    ) -> Result<Option<NonEmpty<(Cid, Arc<Delegation<DID, V, Enc>>)>>, Self::DelegationStoreError>;
 
     fn get_chain_cids(
         &self,
@@ -63,32 +63,34 @@ pub trait Store<DID: Did, V: varsig::Header<Enc>, Enc: Codec + TryFrom<u64> + In
     fn get_many(
         &self,
         cids: &[Cid],
-    ) -> Result<Vec<Option<&Delegation<DID, V, Enc>>>, Self::DelegationStoreError> {
-        cids.iter().try_fold(vec![], |mut acc, cid| {
-            acc.push(self.get(cid)?);
-            Ok(acc)
-        })
+    ) -> Result<Vec<Option<Arc<Delegation<DID, V, Enc>>>>, Self::DelegationStoreError> {
+        cids.iter()
+            .map(|cid| self.get(cid))
+            .collect::<Result<_, Self::DelegationStoreError>>()
     }
 }
 
 impl<T: Store<DID, V, C>, DID: Did, V: varsig::Header<C>, C: Codec + TryFrom<u64> + Into<u64>>
-    Store<DID, V, C> for &mut T
+    Store<DID, V, C> for &T
 {
     type DelegationStoreError = <T as Store<DID, V, C>>::DelegationStoreError;
 
-    fn get(&self, cid: &Cid) -> Result<Option<&Delegation<DID, V, C>>, Self::DelegationStoreError> {
+    fn get(
+        &self,
+        cid: &Cid,
+    ) -> Result<Option<Arc<Delegation<DID, V, C>>>, Self::DelegationStoreError> {
         (**self).get(cid)
     }
 
     fn insert(
-        &mut self,
+        &self,
         cid: Cid,
         delegation: Delegation<DID, V, C>,
     ) -> Result<(), Self::DelegationStoreError> {
         (**self).insert(cid, delegation)
     }
 
-    fn revoke(&mut self, cid: Cid) -> Result<(), Self::DelegationStoreError> {
+    fn revoke(&self, cid: Cid) -> Result<(), Self::DelegationStoreError> {
         (**self).revoke(cid)
     }
 
@@ -99,7 +101,8 @@ impl<T: Store<DID, V, C>, DID: Did, V: varsig::Header<C>, C: Codec + TryFrom<u64
         command: String,
         policy: Vec<Predicate>,
         now: SystemTime,
-    ) -> Result<Option<NonEmpty<(Cid, &Delegation<DID, V, C>)>>, Self::DelegationStoreError> {
+    ) -> Result<Option<NonEmpty<(Cid, Arc<Delegation<DID, V, C>>)>>, Self::DelegationStoreError>
+    {
         (**self).get_chain(audience, subject, command, policy, now)
     }
 }
diff --git a/src/invocation/agent.rs b/src/invocation/agent.rs
index c93e8036..fc5845c3 100644
--- a/src/invocation/agent.rs
+++ b/src/invocation/agent.rs
@@ -27,6 +27,7 @@ use std::{
     collections::{BTreeMap, BTreeSet},
     fmt,
     marker::PhantomData,
+    sync::Arc,
 };
 use thiserror::Error;
 use web_time::SystemTime;
@@ -204,13 +205,19 @@ where
             .put(cid.clone(), invocation.clone())
             .map_err(ReceiveError::InvocationStoreError)?;
 
-        let proof_payloads: Vec<&delegation::Payload<DID>> = self
+        let proofs = &self
             .delegation_store
             .get_many(&invocation.proofs())
-            .map_err(ReceiveError::DelegationStoreError)?
+            .map_err(ReceiveError::DelegationStoreError)?;
+        let proof_payloads: Vec<&delegation::Payload<DID>> = proofs
             .iter()
             .zip(invocation.proofs().iter())
-            .map(|(d, cid)| Ok(&d.ok_or(ReceiveError::MissingDelegation(*cid))?.payload))
+            .map(|(d, cid)| {
+                Ok(&d
+                    .as_ref()
+                    .ok_or(ReceiveError::MissingDelegation(*cid))?
+                    .payload)
+            })
             .collect::<Result<_, ReceiveError<T, DID, D::DelegationStoreError, S, V, C>>>()?;
 
         let _ = &invocation
@@ -748,13 +755,13 @@ mod tests {
             let mut agent: Agent<
                 '_,
                 &mut crate::invocation::store::MemoryStore<AccountManage>,
-                &mut crate::delegation::store::MemoryStore,
+                &crate::delegation::store::MemoryStore,
                 AccountManage,
             > = Agent::new(
                 &ctx.server,
                 &ctx.server_signer,
                 &mut ctx.inv_store,
-                &mut ctx.del_store,
+                &ctx.del_store,
             );
 
             let observed = agent.receive(ctx.account_invocation.clone());
@@ -769,13 +776,13 @@ mod tests {
             let mut agent: Agent<
                 '_,
                 &mut crate::invocation::store::MemoryStore<AccountManage>,
-                &mut crate::delegation::store::MemoryStore,
+                &crate::delegation::store::MemoryStore,
                 AccountManage,
             > = Agent::new(
                 &ctx.server,
                 &ctx.server_signer,
                 &mut ctx.inv_store,
-                &mut ctx.del_store,
+                &ctx.del_store,
             );
 
             let not_account_invocation = crate::Invocation::try_sign(

From 32164a3e199c63fe8d4f04d7f6a1bc8abf84358e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Philipp=20Kr=C3=BCger?= <philipp.krueger1@gmail.com>
Date: Wed, 20 Mar 2024 12:14:55 +0100
Subject: [PATCH 3/7] refactor: Make invocation::Store take &self instead of
 &mut self

---
 src/invocation/agent.rs | 14 ++++-----
 src/invocation/store.rs | 65 ++++++++++++++++++++++++++++++++---------
 2 files changed, 59 insertions(+), 20 deletions(-)

diff --git a/src/invocation/agent.rs b/src/invocation/agent.rs
index fc5845c3..23bd1360 100644
--- a/src/invocation/agent.rs
+++ b/src/invocation/agent.rs
@@ -635,7 +635,7 @@ mod tests {
             );
 
             let inv_store = crate::invocation::store::MemoryStore::default();
-            let mut del_store = crate::delegation::store::MemoryStore::default();
+            let del_store = crate::delegation::store::MemoryStore::default();
 
             // Scenario
             // ========
@@ -750,17 +750,17 @@ mod tests {
 
         #[test_log::test]
         fn test_chain_ok() -> TestResult {
-            let mut ctx = setup_test_chain()?;
+            let ctx = setup_test_chain()?;
 
             let mut agent: Agent<
                 '_,
-                &mut crate::invocation::store::MemoryStore<AccountManage>,
+                &crate::invocation::store::MemoryStore<AccountManage>,
                 &crate::delegation::store::MemoryStore,
                 AccountManage,
             > = Agent::new(
                 &ctx.server,
                 &ctx.server_signer,
-                &mut ctx.inv_store,
+                &ctx.inv_store,
                 &ctx.del_store,
             );
 
@@ -771,17 +771,17 @@ mod tests {
 
         #[test_log::test]
         fn test_chain_wrong_sub() -> TestResult {
-            let mut ctx = setup_test_chain()?;
+            let ctx = setup_test_chain()?;
 
             let mut agent: Agent<
                 '_,
-                &mut crate::invocation::store::MemoryStore<AccountManage>,
+                &crate::invocation::store::MemoryStore<AccountManage>,
                 &crate::delegation::store::MemoryStore,
                 AccountManage,
             > = Agent::new(
                 &ctx.server,
                 &ctx.server_signer,
-                &mut ctx.inv_store,
+                &ctx.inv_store,
                 &ctx.del_store,
             );
 
diff --git a/src/invocation/store.rs b/src/invocation/store.rs
index 26618909..4c9279fa 100644
--- a/src/invocation/store.rs
+++ b/src/invocation/store.rs
@@ -4,6 +4,7 @@ use super::Invocation;
 use crate::ability;
 use crate::{crypto::varsig, did::Did};
 use libipld_core::{cid::Cid, codec::Codec};
+use std::sync::{Arc, RwLock, RwLockReadGuard, RwLockWriteGuard};
 use std::{collections::BTreeMap, convert::Infallible};
 
 pub trait Store<T, DID: Did, V: varsig::Header<C>, C: Codec + Into<u64> + TryFrom<u64>> {
@@ -12,10 +13,10 @@ pub trait Store<T, DID: Did, V: varsig::Header<C>, C: Codec + Into<u64> + TryFro
     fn get(
         &self,
         cid: Cid,
-    ) -> Result<Option<&Invocation<T, DID, V, C>>, Self::InvocationStoreError>;
+    ) -> Result<Option<Arc<Invocation<T, DID, V, C>>>, Self::InvocationStoreError>;
 
     fn put(
-        &mut self,
+        &self,
         cid: Cid,
         invocation: Invocation<T, DID, V, C>,
     ) -> Result<(), Self::InvocationStoreError>;
@@ -31,20 +32,22 @@ impl<
         DID: Did,
         V: varsig::Header<C>,
         C: Codec + Into<u64> + TryFrom<u64>,
-    > Store<T, DID, V, C> for &mut S
+    > Store<T, DID, V, C> for &S
 {
     type InvocationStoreError = <S as Store<T, DID, V, C>>::InvocationStoreError;
 
     fn get(
         &self,
         cid: Cid,
-    ) -> Result<Option<&Invocation<T, DID, V, C>>, <S as Store<T, DID, V, C>>::InvocationStoreError>
-    {
+    ) -> Result<
+        Option<Arc<Invocation<T, DID, V, C>>>,
+        <S as Store<T, DID, V, C>>::InvocationStoreError,
+    > {
         (**self).get(cid)
     }
 
     fn put(
-        &mut self,
+        &self,
         cid: Cid,
         invocation: Invocation<T, DID, V, C>,
     ) -> Result<(), <S as Store<T, DID, V, C>>::InvocationStoreError> {
@@ -52,14 +55,48 @@ impl<
     }
 }
 
-#[derive(Debug, Clone, PartialEq)]
+#[derive(Debug, Clone)]
 pub struct MemoryStore<
     T = crate::ability::preset::Preset,
     DID: crate::did::Did = crate::did::preset::Verifier,
     V: varsig::Header<C> = varsig::header::Preset,
     C: Codec + TryFrom<u64> + Into<u64> = varsig::encoding::Preset,
 > {
-    store: BTreeMap<Cid, Invocation<T, DID, V, C>>,
+    inner: Arc<RwLock<MemoryStoreInner<T, DID, V, C>>>,
+}
+
+#[derive(Debug, Clone, PartialEq)]
+pub struct MemoryStoreInner<
+    T = crate::ability::preset::Preset,
+    DID: crate::did::Did = crate::did::preset::Verifier,
+    V: varsig::Header<C> = varsig::header::Preset,
+    C: Codec + TryFrom<u64> + Into<u64> = varsig::encoding::Preset,
+> {
+    store: BTreeMap<Cid, Arc<Invocation<T, DID, V, C>>>,
+}
+
+impl<T, DID: Did, V: varsig::Header<Enc>, Enc: Codec + Into<u64> + TryFrom<u64>>
+    MemoryStore<T, DID, V, Enc>
+{
+    fn read(&self) -> RwLockReadGuard<'_, MemoryStoreInner<T, DID, V, Enc>> {
+        match self.inner.read() {
+            Ok(guard) => guard,
+            Err(poison) => {
+                // There's no logic errors through lock poisoning in our case
+                poison.into_inner()
+            }
+        }
+    }
+
+    fn write(&self) -> RwLockWriteGuard<'_, MemoryStoreInner<T, DID, V, Enc>> {
+        match self.inner.write() {
+            Ok(guard) => guard,
+            Err(poison) => {
+                // There's no logic errors through lock poisoning in our case
+                poison.into_inner()
+            }
+        }
+    }
 }
 
 impl<T, DID: Did, V: varsig::Header<Enc>, Enc: Codec + Into<u64> + TryFrom<u64>> Default
@@ -67,7 +104,9 @@ impl<T, DID: Did, V: varsig::Header<Enc>, Enc: Codec + Into<u64> + TryFrom<u64>>
 {
     fn default() -> Self {
         Self {
-            store: BTreeMap::new(),
+            inner: Arc::new(RwLock::new(MemoryStoreInner {
+                store: BTreeMap::new(),
+            })),
         }
     }
 }
@@ -80,16 +119,16 @@ impl<T, DID: Did, V: varsig::Header<Enc>, Enc: Codec + Into<u64> + TryFrom<u64>>
     fn get(
         &self,
         cid: Cid,
-    ) -> Result<Option<&Invocation<T, DID, V, Enc>>, Self::InvocationStoreError> {
-        Ok(self.store.get(&cid))
+    ) -> Result<Option<Arc<Invocation<T, DID, V, Enc>>>, Self::InvocationStoreError> {
+        Ok(self.read().store.get(&cid).cloned())
     }
 
     fn put(
-        &mut self,
+        &self,
         cid: Cid,
         invocation: Invocation<T, DID, V, Enc>,
     ) -> Result<(), Self::InvocationStoreError> {
-        self.store.insert(cid, invocation);
+        self.write().store.insert(cid, Arc::new(invocation));
         Ok(())
     }
 }

From 7c50aba4ae8ea286da90dbe044d12c80ef388e88 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Philipp=20Kr=C3=BCger?= <philipp.krueger1@gmail.com>
Date: Wed, 20 Mar 2024 16:19:05 +0100
Subject: [PATCH 4/7] refactor: Make `delegation::Agent` not take `&mut self`
 in methods

---
 src/delegation/agent.rs | 6 +++---
 src/invocation/agent.rs | 8 ++++----
 2 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/src/delegation/agent.rs b/src/delegation/agent.rs
index f7b973d6..3a0565a3 100644
--- a/src/delegation/agent.rs
+++ b/src/delegation/agent.rs
@@ -29,7 +29,7 @@ pub struct Agent<
     pub did: &'a DID,
 
     /// The attached [`deleagtion::Store`][super::store::Store].
-    pub store: &'a mut S,
+    pub store: S,
 
     signer: &'a <DID as Did>::Signer,
     _marker: PhantomData<(V, Enc)>,
@@ -47,7 +47,7 @@ where
     Payload<DID>: TryFrom<Named<Ipld>>,
     Named<Ipld>: From<Payload<DID>>,
 {
-    pub fn new(did: &'a DID, signer: &'a <DID as Did>::Signer, store: &'a mut S) -> Self {
+    pub fn new(did: &'a DID, signer: &'a <DID as Did>::Signer, store: S) -> Self {
         Self {
             did,
             store,
@@ -120,7 +120,7 @@ where
     }
 
     pub fn receive(
-        &mut self,
+        &self,
         cid: Cid, // FIXME remove and generate from the capsule header?
         delegation: Delegation<DID, V, Enc>,
     ) -> Result<(), ReceiveError<S::DelegationStoreError, DID>> {
diff --git a/src/invocation/agent.rs b/src/invocation/agent.rs
index 23bd1360..6fdd306b 100644
--- a/src/invocation/agent.rs
+++ b/src/invocation/agent.rs
@@ -86,7 +86,7 @@ where
     }
 
     pub fn invoke(
-        &mut self,
+        &self,
         audience: Option<DID>,
         subject: DID,
         ability: T,
@@ -172,7 +172,7 @@ where
     // }
 
     pub fn receive(
-        &mut self,
+        &self,
         invocation: Invocation<T, DID, V, C>,
     ) -> Result<Recipient<Payload<T, DID>>, ReceiveError<T, DID, D::DelegationStoreError, S, V, C>>
     where
@@ -184,7 +184,7 @@ where
     }
 
     pub fn generic_receive(
-        &mut self,
+        &self,
         invocation: Invocation<T, DID, V, C>,
         now: SystemTime,
     ) -> Result<Recipient<Payload<T, DID>>, ReceiveError<T, DID, D::DelegationStoreError, S, V, C>>
@@ -233,7 +233,7 @@ where
     }
 
     // pub fn revoke(
-    //     &mut self,
+    //     &self,
     //     subject: DID,
     //     cause: Option<Cid>,
     //     cid: Cid,

From 1971a3d4bdd756175594f2f388537612c18de297 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Philipp=20Kr=C3=BCger?= <philipp.krueger1@gmail.com>
Date: Wed, 20 Mar 2024 12:36:39 +0100
Subject: [PATCH 5/7] refactor: Make `Agent` take `DID` by value

---
 src/invocation/agent.rs | 59 +++++++++++++++--------------------------
 1 file changed, 21 insertions(+), 38 deletions(-)

diff --git a/src/invocation/agent.rs b/src/invocation/agent.rs
index 6fdd306b..11838bde 100644
--- a/src/invocation/agent.rs
+++ b/src/invocation/agent.rs
@@ -34,7 +34,6 @@ use web_time::SystemTime;
 
 #[derive(Debug)]
 pub struct Agent<
-    'a,
     S: Store<T, DID, V, C>,
     D: delegation::store::Store<DID, V, C>,
     T: ToCommand = ability::preset::Preset,
@@ -43,7 +42,7 @@ pub struct Agent<
     C: Codec + Into<u64> + TryFrom<u64> = varsig::encoding::Preset,
 > {
     /// The agent's [`DID`].
-    pub did: &'a DID,
+    pub did: DID,
 
     /// A [`delegation::Store`][delegation::store::Store].
     pub delegation_store: D,
@@ -51,11 +50,11 @@ pub struct Agent<
     /// A [`Store`][Store] for the agent's [`Invocation`]s.
     pub invocation_store: S,
 
-    signer: &'a <DID as Did>::Signer,
+    signer: <DID as Did>::Signer,
     marker: PhantomData<(T, V, C)>,
 }
 
-impl<'a, T, DID, S, D, V, C> Agent<'a, S, D, T, DID, V, C>
+impl<T, DID, S, D, V, C> Agent<S, D, T, DID, V, C>
 where
     Ipld: Encode<C>,
     T: ToCommand + Clone + ParseAbility,
@@ -71,8 +70,8 @@ where
     <D as delegation::store::Store<DID, V, C>>::DelegationStoreError: fmt::Debug,
 {
     pub fn new(
-        did: &'a DID,
-        signer: &'a <DID as Did>::Signer,
+        did: DID,
+        signer: <DID as Did>::Signer,
         invocation_store: S,
         delegation_store: D,
     ) -> Self {
@@ -225,7 +224,7 @@ where
             .check(proof_payloads, now)
             .map_err(ReceiveError::ValidationError)?;
 
-        Ok(if invocation.normalized_audience() != self.did {
+        Ok(if invocation.normalized_audience() != &self.did {
             Recipient::Other(invocation.payload)
         } else {
             Recipient::You(invocation.payload)
@@ -408,11 +407,9 @@ mod tests {
         (verifier, signer)
     }
 
-    fn setup_agent<'a>(
-        did: &'a crate::did::preset::Verifier,
-        signer: &'a crate::did::preset::Signer,
-    ) -> Agent<'a, crate::invocation::store::MemoryStore, crate::delegation::store::MemoryStore>
-    {
+    fn setup_agent(
+    ) -> Agent<crate::invocation::store::MemoryStore, crate::delegation::store::MemoryStore> {
+        let (did, signer) = gen_did();
         let inv_store = crate::invocation::store::MemoryStore::default();
         let del_store = crate::delegation::store::MemoryStore::default();
 
@@ -438,8 +435,7 @@ mod tests {
         #[test_log::test]
         fn test_invoker_is_sub_implicit_aud() -> TestResult {
             let (_nbf, now, exp) = setup_valid_time();
-            let (server, server_signer) = gen_did();
-            let mut agent = setup_agent(&server, &server_signer);
+            let mut agent = setup_agent();
 
             let invocation = agent.invoke(
                 None,
@@ -467,8 +463,7 @@ mod tests {
         #[test_log::test]
         fn test_invoker_is_sub_and_aud() -> TestResult {
             let (_nbf, now, exp) = setup_valid_time();
-            let (server, server_signer) = gen_did();
-            let mut agent = setup_agent(&server, &server_signer);
+            let mut agent = setup_agent();
 
             let invocation = agent.invoke(
                 Some(agent.did.clone()),
@@ -497,8 +492,7 @@ mod tests {
         #[test_log::test]
         fn test_other_recipient() -> TestResult {
             let (_nbf, now, exp) = setup_valid_time();
-            let (server, server_signer) = gen_did();
-            let mut agent = setup_agent(&server, &server_signer);
+            let mut agent = setup_agent();
 
             let (not_server, _) = gen_did();
 
@@ -528,8 +522,7 @@ mod tests {
         #[test_log::test]
         fn test_expired() -> TestResult {
             let (past, now, _exp) = setup_valid_time();
-            let (server, server_signer) = gen_did();
-            let mut agent = setup_agent(&server, &server_signer);
+            let mut agent = setup_agent();
 
             let invocation = agent.invoke(
                 None,
@@ -564,8 +557,8 @@ mod tests {
         #[test_log::test]
         fn test_invalid_sig() -> TestResult {
             let (_past, now, _exp) = setup_valid_time();
-            let (server, server_signer) = gen_did();
-            let mut agent = setup_agent(&server, &server_signer);
+            let mut agent = setup_agent();
+            let server = &agent.did;
 
             let mut invocation = agent.invoke(
                 None,
@@ -752,14 +745,9 @@ mod tests {
         fn test_chain_ok() -> TestResult {
             let ctx = setup_test_chain()?;
 
-            let mut agent: Agent<
-                '_,
-                &crate::invocation::store::MemoryStore<AccountManage>,
-                &crate::delegation::store::MemoryStore,
-                AccountManage,
-            > = Agent::new(
-                &ctx.server,
-                &ctx.server_signer,
+            let mut agent = Agent::new(
+                ctx.server.clone(),
+                ctx.server_signer.clone(),
                 &ctx.inv_store,
                 &ctx.del_store,
             );
@@ -773,14 +761,9 @@ mod tests {
         fn test_chain_wrong_sub() -> TestResult {
             let ctx = setup_test_chain()?;
 
-            let mut agent: Agent<
-                '_,
-                &crate::invocation::store::MemoryStore<AccountManage>,
-                &crate::delegation::store::MemoryStore,
-                AccountManage,
-            > = Agent::new(
-                &ctx.server,
-                &ctx.server_signer,
+            let mut agent = Agent::new(
+                ctx.server.clone(),
+                ctx.server_signer.clone(),
                 &ctx.inv_store,
                 &ctx.del_store,
             );

From 254b7f40e4c2ae327127c7d31dd1965581d3f1ac Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Philipp=20Kr=C3=BCger?= <philipp.krueger1@gmail.com>
Date: Wed, 20 Mar 2024 16:21:15 +0100
Subject: [PATCH 6/7] refactor: Take `DID` by value in `delegation::Agent::new`

---
 src/delegation/agent.rs | 18 ++++++++----------
 1 file changed, 8 insertions(+), 10 deletions(-)

diff --git a/src/delegation/agent.rs b/src/delegation/agent.rs
index 3a0565a3..14d28e56 100644
--- a/src/delegation/agent.rs
+++ b/src/delegation/agent.rs
@@ -19,35 +19,33 @@ use web_time::SystemTime;
 /// This is helpful for sessions where more than one delegation will be made.
 #[derive(Debug)]
 pub struct Agent<
-    'a,
     DID: Did,
     S: Store<DID, V, Enc>,
     V: varsig::Header<Enc>,
     Enc: Codec + TryFrom<u64> + Into<u64>,
 > {
     /// The [`Did`][Did] of the agent.
-    pub did: &'a DID,
+    pub did: DID,
 
     /// The attached [`deleagtion::Store`][super::store::Store].
     pub store: S,
 
-    signer: &'a <DID as Did>::Signer,
+    signer: <DID as Did>::Signer,
     _marker: PhantomData<(V, Enc)>,
 }
 
 impl<
-        'a,
         DID: Did + Clone,
         S: Store<DID, V, Enc> + Clone,
         V: varsig::Header<Enc> + Clone,
         Enc: Codec + TryFrom<u64> + Into<u64>,
-    > Agent<'a, DID, S, V, Enc>
+    > Agent<DID, S, V, Enc>
 where
     Ipld: Encode<Enc>,
     Payload<DID>: TryFrom<Named<Ipld>>,
     Named<Ipld>: From<Payload<DID>>,
 {
-    pub fn new(did: &'a DID, signer: &'a <DID as Did>::Signer, store: S) -> Self {
+    pub fn new(did: DID, signer: <DID as Did>::Signer, store: S) -> Self {
         Self {
             did,
             store,
@@ -73,7 +71,7 @@ where
         let nonce = Nonce::generate_12(&mut salt);
 
         if let Some(ref sub) = subject {
-            if sub == self.did {
+            if sub == &self.did {
                 let payload: Payload<DID> = Payload {
                     issuer: self.did.clone(),
                     audience,
@@ -88,7 +86,7 @@ where
                 };
 
                 return Ok(
-                    Delegation::try_sign(self.signer, varsig_header, payload).expect("FIXME")
+                    Delegation::try_sign(&self.signer, varsig_header, payload).expect("FIXME")
                 );
             }
         }
@@ -116,7 +114,7 @@ where
             not_before: not_before.map(Into::into),
         };
 
-        Ok(Delegation::try_sign(self.signer, varsig_header, payload).expect("FIXME"))
+        Ok(Delegation::try_sign(&self.signer, varsig_header, payload).expect("FIXME"))
     }
 
     pub fn receive(
@@ -128,7 +126,7 @@ where
             return Ok(());
         }
 
-        if delegation.audience() != self.did {
+        if delegation.audience() != &self.did {
             return Err(ReceiveError::WrongAudience(delegation.audience().clone()));
         }
 

From 0c8a7180ed178bc260c30fc20d101556e2e68e0f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Philipp=20Kr=C3=BCger?= <philipp.krueger1@gmail.com>
Date: Wed, 20 Mar 2024 16:24:27 +0100
Subject: [PATCH 7/7] refactor: Change generic order in `delegation::Agent` and
 add defaults

---
 src/delegation/agent.rs | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/src/delegation/agent.rs b/src/delegation/agent.rs
index 14d28e56..bfee4119 100644
--- a/src/delegation/agent.rs
+++ b/src/delegation/agent.rs
@@ -1,5 +1,6 @@
 use super::{payload::Payload, policy::Predicate, store::Store, Delegation};
 use crate::ability::arguments::Named;
+use crate::did;
 use crate::{
     crypto::{signature::Envelope, varsig, Nonce},
     did::Did,
@@ -19,10 +20,10 @@ use web_time::SystemTime;
 /// This is helpful for sessions where more than one delegation will be made.
 #[derive(Debug)]
 pub struct Agent<
-    DID: Did,
     S: Store<DID, V, Enc>,
-    V: varsig::Header<Enc>,
-    Enc: Codec + TryFrom<u64> + Into<u64>,
+    DID: Did = did::preset::Verifier,
+    V: varsig::Header<Enc> + Clone = varsig::header::Preset,
+    Enc: Codec + Into<u64> + TryFrom<u64> = varsig::encoding::Preset,
 > {
     /// The [`Did`][Did] of the agent.
     pub did: DID,
@@ -35,11 +36,11 @@ pub struct Agent<
 }
 
 impl<
-        DID: Did + Clone,
         S: Store<DID, V, Enc> + Clone,
+        DID: Did + Clone,
         V: varsig::Header<Enc> + Clone,
         Enc: Codec + TryFrom<u64> + Into<u64>,
-    > Agent<DID, S, V, Enc>
+    > Agent<S, DID, V, Enc>
 where
     Ipld: Encode<Enc>,
     Payload<DID>: TryFrom<Named<Ipld>>,