A subscriptions transport coalescer

packages/rpc-subscriptions/README.md

@@ -48,3 +48,7 @@ Given an `RpcSubscriptionsChannel`, will return a new channel that parses data p
 ### `getRpcSubscriptionsChannelWithAutoping(channel)`
 
 Given an `RpcSubscriptionsChannel`, will return a new channel that sends a ping message to the inner channel if a message has not been sent or received in the last `intervalMs`. In web browsers, this implementation sends no ping when the network is down, and sends a ping immediately upon the network coming back up.
+
+### `getRpcSubscriptionsTransportWithSubscriptionCoalescing(transport)`
+
+Given an `RpcSubscriptionsTransport`, will return a new transport that coalesces identical subscriptions into a single subscription request to the server. The determination of whether a subscription is the same as another is based on the `subscriptionConfigurationHash` returned by its `RpcSubscriptionsPlan`. The subscription will only be aborted once all subscribers abort, or there is an error.

packages/rpc-subscriptions/package.json

@@ -78,7 +78,8 @@
         "@solana/rpc-subscriptions-channel-websocket": "workspace:*",
         "@solana/rpc-subscriptions-spec": "workspace:*",
         "@solana/rpc-transformers": "workspace:*",
-        "@solana/rpc-types": "workspace:*"
+        "@solana/rpc-types": "workspace:*",
+        "@solana/subscribable": "workspace:*"
     },
     "peerDependencies": {
         "typescript": ">=5"