parveensania commented on code in PR #37840: URL: https://github.com/apache/beam/pull/37840#discussion_r2979107761
########## runners/google-cloud-dataflow-java/worker/src/main/java/org/apache/beam/runners/dataflow/worker/windmill/client/grpc/stubs/FailoverChannel.java: ########## @@ -0,0 +1,303 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one + * or more contributor license agreements. See the NOTICE file + * distributed with this work for additional information + * regarding copyright ownership. The ASF licenses this file + * to you under the Apache License, Version 2.0 (the + * "License"); you may not use this file except in compliance + * with the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ +package org.apache.beam.runners.dataflow.worker.windmill.client.grpc.stubs; + +import java.util.concurrent.TimeUnit; +import java.util.concurrent.atomic.AtomicBoolean; +import java.util.concurrent.atomic.AtomicLong; +import java.util.function.LongSupplier; +import javax.annotation.Nullable; +import org.apache.beam.sdk.annotations.Internal; +import org.apache.beam.vendor.grpc.v1p69p0.io.grpc.CallCredentials; +import org.apache.beam.vendor.grpc.v1p69p0.io.grpc.CallOptions; +import org.apache.beam.vendor.grpc.v1p69p0.io.grpc.ClientCall; +import org.apache.beam.vendor.grpc.v1p69p0.io.grpc.ConnectivityState; +import org.apache.beam.vendor.grpc.v1p69p0.io.grpc.ForwardingClientCall.SimpleForwardingClientCall; +import org.apache.beam.vendor.grpc.v1p69p0.io.grpc.ForwardingClientCallListener.SimpleForwardingClientCallListener; +import org.apache.beam.vendor.grpc.v1p69p0.io.grpc.ManagedChannel; +import org.apache.beam.vendor.grpc.v1p69p0.io.grpc.Metadata; +import org.apache.beam.vendor.grpc.v1p69p0.io.grpc.MethodDescriptor; +import org.apache.beam.vendor.grpc.v1p69p0.io.grpc.Status; +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +/** + * A {@link ManagedChannel} that wraps a primary and a fallback channel. + * + * <p>Routes requests to either primary or fallback channel based on two independent failover modes: + * + * <ul> + * <li><b>Connection Status Failover:</b> If the primary channel is not ready for 10+ seconds + * (e.g., during network issues), routes to fallback channel. Switches back as soon as the + * primary channel becomes READY again. + * <li><b>RPC Failover:</b> If primary channel RPC fails with transient errors ({@link + * Status.Code#UNAVAILABLE}, {@link Status.Code#DEADLINE_EXCEEDED}, or {@link + * Status.Code#UNKNOWN}), switches to fallback channel and waits for a 1-hour cooling period + * before retrying primary. + * </ul> + */ +@Internal +public final class FailoverChannel extends ManagedChannel { + private static final Logger LOG = LoggerFactory.getLogger(FailoverChannel.class); + // Time to wait before retrying the primary channel after an RPC-based fallback. + private static final long FALLBACK_COOLING_PERIOD_NANOS = TimeUnit.HOURS.toNanos(1); + private static final long PRIMARY_NOT_READY_WAIT_NANOS = TimeUnit.SECONDS.toNanos(10); + private final ManagedChannel primary; + @Nullable private final ManagedChannel fallback; + @Nullable private final CallCredentials fallbackCallCredentials; + // Set when primary's connection state has been unavailable for too long. + private final AtomicBoolean useFallbackDueToState = new AtomicBoolean(false); + // Set when an RPC on primary fails with a transient error. + private final AtomicBoolean useFallbackDueToRPC = new AtomicBoolean(false); + private final AtomicLong lastRPCFallbackTimeNanos = new AtomicLong(0); + private final AtomicLong primaryNotReadySinceNanos = new AtomicLong(-1); + private final LongSupplier nanoClock; + private final AtomicBoolean stateChangeListenerRegistered = new AtomicBoolean(false); + + private FailoverChannel( + ManagedChannel primary, + @Nullable ManagedChannel fallback, + @Nullable CallCredentials fallbackCallCredentials, + LongSupplier nanoClock) { + this.primary = primary; + this.fallback = fallback; + this.fallbackCallCredentials = fallbackCallCredentials; + this.nanoClock = nanoClock; + // Register callback to monitor primary channel state changes + registerPrimaryStateChangeListener(); + } + + // Test-only. + public static FailoverChannel create(ManagedChannel primary, ManagedChannel fallback) { + return new FailoverChannel(primary, fallback, null, System::nanoTime); + } + + public static FailoverChannel create( + ManagedChannel primary, ManagedChannel fallback, CallCredentials fallbackCallCredentials) { + return new FailoverChannel(primary, fallback, fallbackCallCredentials, System::nanoTime); + } + + static FailoverChannel forTest( + ManagedChannel primary, + ManagedChannel fallback, + CallCredentials fallbackCallCredentials, + LongSupplier nanoClock) { + return new FailoverChannel(primary, fallback, fallbackCallCredentials, nanoClock); + } + + @Override + public String authority() { + return primary.authority(); + } + + @Override + public <ReqT, RespT> ClientCall<ReqT, RespT> newCall( + MethodDescriptor<ReqT, RespT> methodDescriptor, CallOptions callOptions) { + // Check if the RPC-based cooling period has elapsed. + if (useFallbackDueToRPC.get()) { + long timeSinceLastFallback = nanoClock.getAsLong() - lastRPCFallbackTimeNanos.get(); + if (timeSinceLastFallback >= FALLBACK_COOLING_PERIOD_NANOS) { + if (useFallbackDueToRPC.compareAndSet(true, false)) { + LOG.info("Primary channel cooling period elapsed; switching back from fallback."); + } + } + } + + if (fallback != null && (useFallbackDueToRPC.get() || useFallbackDueToState.get())) { + return new FailoverClientCall<>( + fallback.newCall(methodDescriptor, applyFallbackCredentials(callOptions)), + true, + methodDescriptor.getFullMethodName()); + } + + // If primary has not become ready for a sustained period, fail over to fallback. + if (fallback != null && shouldFallBackDueToPrimaryState()) { + if (useFallbackDueToState.compareAndSet(false, true)) { + LOG.warn("Primary connection unavailable. Switching to secondary connection."); + } + return new FailoverClientCall<>( + fallback.newCall(methodDescriptor, applyFallbackCredentials(callOptions)), + true, + methodDescriptor.getFullMethodName()); + } + + return new FailoverClientCall<>( + primary.newCall(methodDescriptor, callOptions), + false, + methodDescriptor.getFullMethodName()); + } + + @Override + public ManagedChannel shutdown() { + primary.shutdown(); + if (fallback != null) { + fallback.shutdown(); + } + return this; + } + + @Override + public ManagedChannel shutdownNow() { + primary.shutdownNow(); + if (fallback != null) { + fallback.shutdownNow(); + } + return this; + } + + @Override + public boolean isShutdown() { + return primary.isShutdown() && (fallback == null || fallback.isShutdown()); + } + + @Override + public boolean isTerminated() { + return primary.isTerminated() && (fallback == null || fallback.isTerminated()); + } + + @Override + public boolean awaitTermination(long timeout, TimeUnit unit) throws InterruptedException { + long endTimeNanos = nanoClock.getAsLong() + unit.toNanos(timeout); + boolean primaryTerminated = primary.awaitTermination(timeout, unit); + if (fallback != null) { + long remainingNanos = Math.max(0, endTimeNanos - nanoClock.getAsLong()); + return primaryTerminated && fallback.awaitTermination(remainingNanos, TimeUnit.NANOSECONDS); + } + return primaryTerminated; + } + + private boolean shouldFallbackBasedOnRPCStatus(Status status) { + switch (status.getCode()) { + case UNAVAILABLE: + case DEADLINE_EXCEEDED: + case UNKNOWN: + return true; + default: + return false; + } + } + + private boolean hasFallbackChannel() { + return fallback != null; + } + + private CallOptions applyFallbackCredentials(CallOptions callOptions) { + if (fallbackCallCredentials != null && callOptions.getCredentials() == null) { + return callOptions.withCallCredentials(fallbackCallCredentials); + } + return callOptions; + } + + private boolean shouldFallBackDueToPrimaryState() { + ConnectivityState connectivityState = primary.getState(true); Review Comment: Done. The original change was to retry connection. But looks like grpc already retries failed connections, so this was unnecessary. Also, if getState returns IDLE, we not treat it as healthy. ########## runners/google-cloud-dataflow-java/worker/src/main/java/org/apache/beam/runners/dataflow/worker/windmill/client/grpc/stubs/FailoverChannel.java: ########## @@ -0,0 +1,303 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one + * or more contributor license agreements. See the NOTICE file + * distributed with this work for additional information + * regarding copyright ownership. The ASF licenses this file + * to you under the Apache License, Version 2.0 (the + * "License"); you may not use this file except in compliance + * with the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ +package org.apache.beam.runners.dataflow.worker.windmill.client.grpc.stubs; + +import java.util.concurrent.TimeUnit; +import java.util.concurrent.atomic.AtomicBoolean; +import java.util.concurrent.atomic.AtomicLong; +import java.util.function.LongSupplier; +import javax.annotation.Nullable; +import org.apache.beam.sdk.annotations.Internal; +import org.apache.beam.vendor.grpc.v1p69p0.io.grpc.CallCredentials; +import org.apache.beam.vendor.grpc.v1p69p0.io.grpc.CallOptions; +import org.apache.beam.vendor.grpc.v1p69p0.io.grpc.ClientCall; +import org.apache.beam.vendor.grpc.v1p69p0.io.grpc.ConnectivityState; +import org.apache.beam.vendor.grpc.v1p69p0.io.grpc.ForwardingClientCall.SimpleForwardingClientCall; +import org.apache.beam.vendor.grpc.v1p69p0.io.grpc.ForwardingClientCallListener.SimpleForwardingClientCallListener; +import org.apache.beam.vendor.grpc.v1p69p0.io.grpc.ManagedChannel; +import org.apache.beam.vendor.grpc.v1p69p0.io.grpc.Metadata; +import org.apache.beam.vendor.grpc.v1p69p0.io.grpc.MethodDescriptor; +import org.apache.beam.vendor.grpc.v1p69p0.io.grpc.Status; +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +/** + * A {@link ManagedChannel} that wraps a primary and a fallback channel. + * + * <p>Routes requests to either primary or fallback channel based on two independent failover modes: + * + * <ul> + * <li><b>Connection Status Failover:</b> If the primary channel is not ready for 10+ seconds + * (e.g., during network issues), routes to fallback channel. Switches back as soon as the + * primary channel becomes READY again. + * <li><b>RPC Failover:</b> If primary channel RPC fails with transient errors ({@link + * Status.Code#UNAVAILABLE}, {@link Status.Code#DEADLINE_EXCEEDED}, or {@link + * Status.Code#UNKNOWN}), switches to fallback channel and waits for a 1-hour cooling period + * before retrying primary. + * </ul> + */ +@Internal +public final class FailoverChannel extends ManagedChannel { + private static final Logger LOG = LoggerFactory.getLogger(FailoverChannel.class); + // Time to wait before retrying the primary channel after an RPC-based fallback. + private static final long FALLBACK_COOLING_PERIOD_NANOS = TimeUnit.HOURS.toNanos(1); + private static final long PRIMARY_NOT_READY_WAIT_NANOS = TimeUnit.SECONDS.toNanos(10); + private final ManagedChannel primary; + @Nullable private final ManagedChannel fallback; + @Nullable private final CallCredentials fallbackCallCredentials; + // Set when primary's connection state has been unavailable for too long. + private final AtomicBoolean useFallbackDueToState = new AtomicBoolean(false); + // Set when an RPC on primary fails with a transient error. + private final AtomicBoolean useFallbackDueToRPC = new AtomicBoolean(false); + private final AtomicLong lastRPCFallbackTimeNanos = new AtomicLong(0); + private final AtomicLong primaryNotReadySinceNanos = new AtomicLong(-1); + private final LongSupplier nanoClock; + private final AtomicBoolean stateChangeListenerRegistered = new AtomicBoolean(false); + + private FailoverChannel( + ManagedChannel primary, + @Nullable ManagedChannel fallback, Review Comment: Done -- This is an automated message from the Apache Git Service. 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