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Improve fallback host resolution in connection logic #1242

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Merged
ttypic merged 1 commit into from
Sep 14, 2026
+14 −9
Merged

Improve fallback host resolution in connection logic #1242

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23 changes: 14 additions & 9 deletions lib/src/main/java/io/ably/lib/transport/ConnectionManager.java
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Original file line number Diff line number Diff line change
Expand Up @@ -1471,21 +1471,26 @@ private synchronized void setSuspendTime() {
suspendTime = (clock.currentTimeMillis() + connectionStateTtl);
}

private boolean shouldTryFallback(TransportParams params, ErrorInfo reason) {
return params != null && (reason == null || reason.statusCode >= 500);
}

/**
* After a connection attempt failed, check to
* see whether we should attempt to use a fallback.
* @param reason
* @return StateIndication if a fallback connection attempt is required, otherwise null
*/
private StateIndication checkFallback(ErrorInfo reason) {
if(pendingConnect != null && (reason == null || reason.statusCode >= 500)) {
if (checkConnectivity()) {
/* we will try a fallback host */
String hostFallback = hosts.getFallback(pendingConnect.host);
if (hostFallback != null) {
Log.v(TAG, "checkFallback: fallback to " + hostFallback);
return new StateIndication(ConnectionState.connecting, null, hostFallback, pendingConnect.host);
}
// checkConnectivity is blocking http call, try to avoid it if we don't need to try fallback
TransportParams pendingConnectionParams = pendingConnect;
boolean internetIsUp = shouldTryFallback(pendingConnectionParams, reason) && checkConnectivity();
if (internetIsUp) {
/* we will try a fallback host */
String hostFallback = hosts.getFallback(pendingConnectionParams.host);
if (hostFallback != null && pendingConnectionParams == pendingConnect) {
Log.v(TAG, "checkFallback: fallback to " + hostFallback);
return new StateIndication(ConnectionState.connecting, null, hostFallback, pendingConnectionParams.host);
}
}
pendingConnect = null;
Expand Down Expand Up @@ -2033,7 +2038,7 @@ private boolean isFatalError(ErrorInfo err) {
private final Map<ConnectionState, State> states = new HashMap<>();
private State currentState;
private ErrorInfo stateError;
private ConnectParams pendingConnect;
private volatile ConnectParams pendingConnect;
private boolean suppressRetry; /* for tests only; modified via reflection */
private volatile ITransport transport;
private long suspendTime;
Expand Down
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