cleanup(state): condenses match arms for redirected StateService requ…

…ests and moves metrics counting to Request methods (#5137)

* Move AwaitUtxos next to the other shared writeable state requests

* Rename ReadResponse::Utxos to ReadResponse::AddressUtxos

```sh
fastmod Utxos AddressUtxos zebra*
```

* Rename an out_point variable to outpoint for consistency

* Rename transparent_utxos to address_utxos

```sh
fastmod transparent_utxos address_utxos zebra*
```

* Run AwaitUtxo without accessing shared mutable chain state

* Fix some incorrect comments

* Explain why some concurrent reads are ok

* Add a TODO

* Stop using self.mem in AwaitUtxo requests

* Update state service module documentation

* Move the QueuedBlock type into the queued_blocks module

* Explain how spent UTXOs are treated by the state

* Clarify how cached Chains impact state read requests

And move repeated comments to the module header.

* fastmod ChainUtxo BestChainUtxo zebra*

* Add an AnyChainUtxo request

* Make AwaitUtxo non-blocking

* Move the finalized block queue into the StateService

* Move the queued_blocks module to the state service

* Move QueuedFinalized into queued_blocks

* Move the queued_blocks tests into their own module

* Make the FinalizedState cloneable

* cleanup of repetitive code

* fixes merge by adding back req.count_metric and removing the metrics::counter in AwaitUtxo

Co-authored-by: teor <[email protected]>

zebra-state/src/request.rs

@@ -511,6 +511,33 @@ pub enum Request {
     },
 }
 
+impl Request {
+    fn variant_name(&self) -> &'static str {
+        match self {
+            Request::CommitBlock(_) => "commit_block",
+            Request::CommitFinalizedBlock(_) => "commit_finalized_block",
+            Request::AwaitUtxo(_) => "await_utxo",
+            Request::Depth(_) => "depth",
+            Request::Tip => "tip",
+            Request::BlockLocator => "block_locator",
+            Request::Transaction(_) => "transaction",
+            Request::Block(_) => "block",
+            Request::FindBlockHashes { .. } => "find_block_hashes",
+            Request::FindBlockHeaders { .. } => "find_block_headers",
+        }
+    }
+
+    /// Counts metric for StateService call
+    pub fn count_metric(&self) {
+        metrics::counter!(
+            "state.requests",
+            1,
+            "service" => "state",
+            "type" => self.variant_name()
+        );
+    }
+}
+
 #[derive(Clone, Debug, PartialEq, Eq)]
 /// A read-only query about the chain state, via the
 /// [`ReadStateService`](crate::service::ReadStateService).
@@ -670,6 +697,37 @@ pub enum ReadRequest {
     UtxosByAddresses(HashSet<transparent::Address>),
 }
 
+impl ReadRequest {
+    fn variant_name(&self) -> &'static str {
+        match self {
+            ReadRequest::Tip => "tip",
+            ReadRequest::Depth(_) => "depth",
+            ReadRequest::Block(_) => "block",
+            ReadRequest::Transaction(_) => "transaction",
+            ReadRequest::BestChainUtxo { .. } => "best_chain_utxo",
+            ReadRequest::AnyChainUtxo { .. } => "any_chain_utxo",
+            ReadRequest::BlockLocator => "block_locator",
+            ReadRequest::FindBlockHashes { .. } => "find_block_hashes",
+            ReadRequest::FindBlockHeaders { .. } => "find_block_headers",
+            ReadRequest::SaplingTree { .. } => "sapling_tree",
+            ReadRequest::OrchardTree { .. } => "orchard_tree",
+            ReadRequest::AddressBalance { .. } => "address_balance",
+            ReadRequest::TransactionIdsByAddresses { .. } => "transaction_ids_by_addesses",
+            ReadRequest::UtxosByAddresses(_) => "utxos_by_addesses",
+        }
+    }
+
+    /// Counts metric for ReadStateService call
+    pub fn count_metric(&self) {
+        metrics::counter!(
+            "state.requests",
+            1,
+            "service" => "read_state",
+            "type" => self.variant_name()
+        );
+    }
+}
+
 /// Conversion from read-write [`Request`]s to read-only [`ReadRequest`]s.
 ///
 /// Used to dispatch read requests concurrently from the [`StateService`](crate::service::StateService).