taler-typescript-core

commit 5f00bcf20b16940f6761a9ec58117ea7ff665ada
parent d983ff060560c0e0807020047676d46d97077cc3
Author: Florian Dold <dold@taler.net>
Date:   Thu,  3 Sep 2026 15:47:37 +0200

wallet-core: hand a released lock straight to its waiter

Deleting the lock before resuming the waiter left a window in which a
newcomer could take it, so two callers ran the sections around the
melt and pay requests at once.

Diffstat:
M
packages/taler-wallet-core/src/sequential-locks.ts
 | 
10
++++++++--

1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/packages/taler-wallet-core/src/sequential-locks.ts b/packages/taler-wallet-core/src/sequential-locks.ts
@@ -39,19 +39,25 @@ export class SequentialLocks {
           waitList = this.waiters[token] = [];
         }
         waitList.push(p);
+        // The holder passes the lock on when it resolves us, so it is
+        // already ours once we resume.
         await p.promise;
+      } else {
+        this.locks.add(token);
       }
-      this.locks.add(token);
     }
 
     try {
       return await f();
     } finally {
       for (const token of tokens) {
-        this.locks.delete(token);
         const waiter = (this.waiters[token] ?? []).shift();
         if (waiter) {
+          // Ownership moves to the waiter without the lock ever being free,
+          // so nobody else can slip in before the waiter resumes.
           waiter.resolve();
+        } else {
+          this.locks.delete(token);
         }
       }
     }