Handle race condition where Alfie initiates reconciliation before Bet…

…ty realises there is an intersection.
earthstar-project · May 15, 2024 · 8016dd4 · 8016dd4
1 parent 7a6ebd3
commit 8016dd4
Show file tree

Hide file tree

Showing 2 changed files with 67 additions and 1 deletion.
diff --git a/src/wgps/reconciliation/reconciler_map.ts b/src/wgps/reconciliation/reconciler_map.ts
@@ -1,3 +1,4 @@
+import { Deferred, deferred } from "../../../deps.ts";
 import { WgpsMessageValidationError, WillowError } from "../../errors.ts";
 import { Reconciler } from "./reconciler.ts";
 
@@ -28,6 +29,21 @@ export class ReconcilerMap<
     >
   >();
 
+  private eventuallyMap = new Map<
+    string,
+    Deferred<
+      Reconciler<
+        NamespaceId,
+        SubspaceId,
+        PayloadDigest,
+        AuthorisationOpts,
+        AuthorisationToken,
+        Prefingerprint,
+        Fingerprint
+      >
+    >
+  >();
+
   addReconciler(
     aoiHandleOurs: bigint,
     aoiHandleTheirs: bigint,
@@ -64,12 +80,59 @@ export class ReconcilerMap<
     newInnerMap.set(aoiHandleTheirs, reconciler);
 
     this.map.set(aoiHandleOurs, newInnerMap);
+
+    const maybeEventually = this.eventuallyMap.get(
+      `${aoiHandleOurs}_${aoiHandleTheirs}`,
+    );
+
+    if (maybeEventually) {
+      maybeEventually.resolve(reconciler);
+    }
+  }
+
+  getReconcilerEventually(
+    aoiHandleOurs: bigint,
+    aoiHandleTheirs: bigint,
+  ): Promise<
+    Reconciler<
+      NamespaceId,
+      SubspaceId,
+      PayloadDigest,
+      AuthorisationOpts,
+      AuthorisationToken,
+      Prefingerprint,
+      Fingerprint
+    >
+  > {
+    try {
+      return Promise.resolve(
+        this.getReconciler(aoiHandleOurs, aoiHandleTheirs),
+      );
+    } catch {
+      const promise = deferred<
+        Reconciler<
+          NamespaceId,
+          SubspaceId,
+          PayloadDigest,
+          AuthorisationOpts,
+          AuthorisationToken,
+          Prefingerprint,
+          Fingerprint
+        >
+      >();
+
+      this.eventuallyMap.set(`${aoiHandleOurs}_${aoiHandleTheirs}`, promise);
+
+      return promise;
+    }
   }
 
   getReconciler(aoiHandleOurs: bigint, aoiHandleTheirs: bigint) {
     const innerMap = this.map.get(aoiHandleOurs);
 
     if (!innerMap) {
+      console.log("oh shit!!!");
+
       throw new WillowError(
         "Could not dereference one of our AOI handles to a reconciler",
       );

diff --git a/src/wgps/wgps_messenger.ts b/src/wgps/wgps_messenger.ts
@@ -731,12 +731,14 @@ export class WgpsMessenger<
 
     // Begin handling decoded messages
     onAsyncIterate(decodedMessages, (msg) => {
+      /*
       console.log(
         `%c${this.transport.role === IS_ALFIE ? "Alfie" : "Betty"} got: ${
           messageNames[msg.kind]
         }`,
         `color: ${this.transport.role === IS_ALFIE ? "red" : "blue"}`,
       );
+      */
 
       if (msg.kind === MsgKind.DataSendEntry) {
         this.currentlyReceivedEntry = msg.entry;
@@ -1315,7 +1317,8 @@ export class WgpsMessenger<
   ) {
     switch (message.kind) {
       case MsgKind.ReconciliationSendFingerprint: {
-        const reconciler = this.reconcilerMap.getReconciler(
+        // Alfie may have initiated reconciliation before we realised there was even an intersection, so we need to wait until we've realised that intersection exists as well.
+        const reconciler = await this.reconcilerMap.getReconcilerEventually(
           message.receiverHandle,
           message.senderHandle,
         );