Increase snap task timeouts to handle cold-cache server latency

The Besu snap server performs synchronous disk I/O (trie proof generation)
on the Netty event loop, which can exceed 5s on cold RocksDB cache. This
caused clients to timeout before receiving a response, accumulating 5
timeout counts and triggering a TIMEOUT disconnect.

Fix: raise GetAccountRangeFromPeerTask timeout to 20s for sync tasks,
10s for the snap server probe, and widen the EthPeers probe wait to 12s.
Also fix SnapServerChecker to complete the future on probe failure so
isServingSnap is not incorrectly set to false.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: macfarla

ethereum/eth/src/main/java/org/hyperledger/besu/ethereum/eth/manager/EthPeers.java

@@ -654,7 +654,7 @@ private void checkIsSnapServer(final EthPeer peer, final BlockHeader peersHeadBl
         peer.setIsServingSnap(true);
         Boolean isServer;
         try {
-          isServer = snapServerChecker.check(peer, peersHeadBlockHeader).get(6L, TimeUnit.SECONDS);
+          isServer = snapServerChecker.check(peer, peersHeadBlockHeader).get(12L, TimeUnit.SECONDS);
         } catch (Exception e) {
           LOG.atTrace()
               .setMessage("Error checking if peer {} is a snap server. Setting to false.")

ethereum/eth/src/main/java/org/hyperledger/besu/ethereum/eth/manager/snap/RetryingGetAccountRangeFromPeerTask.java

@@ -72,6 +72,9 @@ protected CompletableFuture<AccountRangeMessage.AccountRangeData> executeTaskOnC
     final GetAccountRangeFromPeerTask task =
         GetAccountRangeFromPeerTask.forAccountRange(
             ethContext, startKeyHash, endKeyHash, blockHeader, metricsSystem);
+    // Use a longer timeout than the default 5s: the snap server does synchronous disk I/O
+    // (trie proof generation) on the Netty event loop, which can exceed 5s on cold cache.
+    task.setTimeout(java.time.Duration.ofSeconds(20));
     return executeSubTask(task::run)
         .thenApply(
             peerResult -> {

ethereum/eth/src/main/java/org/hyperledger/besu/ethereum/eth/sync/SnapServerChecker.java

@@ -72,20 +72,30 @@ public CompletableFuture<Boolean> check(final EthPeer peer, final BlockHeader pe
                   .log();
               future.complete(false);
             }
+          } else {
+            LOG.atTrace()
+                .setMessage("Snap server probe for peer {} failed ({}), marking as not a snap server.")
+                .addArgument(peer::getLoggableId)
+                .addArgument(error != null ? error.getMessage() : "cancelled")
+                .log();
+            future.complete(false);
           }
         });
     return future;
   }
 
   public CompletableFuture<AbstractPeerTask.PeerTaskResult<AccountRangeMessage.AccountRangeData>>
       getAccountRangeFromPeer(final EthPeer peer, final BlockHeader header) {
-    return GetAccountRangeFromPeerTask.forAccountRange(
+    final GetAccountRangeFromPeerTask task =
+        GetAccountRangeFromPeerTask.forAccountRange(
             ethContext,
             Bytes32.wrap(Hash.ZERO.getBytes()),
             Bytes32.wrap(Hash.ZERO.getBytes()),
             header,
-            metricsSystem)
-        .assignPeer(peer)
-        .run();
+            metricsSystem);
+    // Use a longer timeout than the default 5s: the snap server does synchronous disk I/O
+    // (trie proof generation) on the Netty event loop, which can exceed 5s on cold cache.
+    task.setTimeout(java.time.Duration.ofSeconds(10));
+    return task.assignPeer(peer).run();
   }
 }