io.grpc.internal.InternalSubchannel Maven / Gradle / Ivy
/*
* Copyright 2015 The gRPC Authors
*
* Licensed 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 io.grpc.internal;
import static io.grpc.ConnectivityState.CONNECTING;
import static io.grpc.ConnectivityState.IDLE;
import static io.grpc.ConnectivityState.READY;
import static io.grpc.ConnectivityState.SHUTDOWN;
import static io.grpc.ConnectivityState.TRANSIENT_FAILURE;
import com.google.common.annotations.VisibleForTesting;
import com.google.common.base.MoreObjects;
import com.google.common.base.Preconditions;
import com.google.common.base.Stopwatch;
import com.google.common.base.Supplier;
import com.google.common.util.concurrent.ListenableFuture;
import com.google.common.util.concurrent.SettableFuture;
import com.google.errorprone.annotations.ForOverride;
import io.grpc.Attributes;
import io.grpc.CallOptions;
import io.grpc.ChannelLogger;
import io.grpc.ChannelLogger.ChannelLogLevel;
import io.grpc.ClientStreamTracer;
import io.grpc.ClientTransportFilter;
import io.grpc.ConnectivityState;
import io.grpc.ConnectivityStateInfo;
import io.grpc.EquivalentAddressGroup;
import io.grpc.HttpConnectProxiedSocketAddress;
import io.grpc.InternalChannelz;
import io.grpc.InternalChannelz.ChannelStats;
import io.grpc.InternalInstrumented;
import io.grpc.InternalLogId;
import io.grpc.InternalWithLogId;
import io.grpc.Metadata;
import io.grpc.MethodDescriptor;
import io.grpc.Status;
import io.grpc.SynchronizationContext;
import io.grpc.SynchronizationContext.ScheduledHandle;
import java.net.SocketAddress;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.List;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.TimeUnit;
import javax.annotation.Nullable;
import javax.annotation.concurrent.ThreadSafe;
/**
* Transports for a single {@link SocketAddress}.
*/
@ThreadSafe
final class InternalSubchannel implements InternalInstrumented, TransportProvider {
private final InternalLogId logId;
private final String authority;
private final String userAgent;
private final BackoffPolicy.Provider backoffPolicyProvider;
private final Callback callback;
private final ClientTransportFactory transportFactory;
private final ScheduledExecutorService scheduledExecutor;
private final InternalChannelz channelz;
private final CallTracer callsTracer;
private final ChannelTracer channelTracer;
private final ChannelLogger channelLogger;
private final List transportFilters;
/**
* All field must be mutated in the syncContext.
*/
private final SynchronizationContext syncContext;
/**
* The index of the address corresponding to pendingTransport/activeTransport, or at beginning if
* both are null.
*
* Note: any {@link Index#updateAddresses(List)} should also update {@link #addressGroups}.
*/
private final Index addressIndex;
/**
* A volatile accessor to {@link Index#getAddressGroups()}. There are few methods ({@link
* #getAddressGroups()} and {@link #toString()} access this value where they supposed to access
* in the {@link #syncContext}. Ideally {@link Index#getAddressGroups()} can be volatile, so we
* don't need to maintain this volatile accessor. Although, having this accessor can reduce
* unnecessary volatile reads while it delivers clearer intention of why .
*/
private volatile List addressGroups;
/**
* The policy to control back off between reconnects. Non-{@code null} when a reconnect task is
* scheduled.
*/
private BackoffPolicy reconnectPolicy;
/**
* Timer monitoring duration since entering CONNECTING state.
*/
private final Stopwatch connectingTimer;
@Nullable
private ScheduledHandle reconnectTask;
@Nullable
private ScheduledHandle shutdownDueToUpdateTask;
@Nullable
private ManagedClientTransport shutdownDueToUpdateTransport;
/**
* All transports that are not terminated. At the very least the value of {@link #activeTransport}
* will be present, but previously used transports that still have streams or are stopping may
* also be present.
*/
private final Collection transports = new ArrayList<>();
// Must only be used from syncContext
private final InUseStateAggregator inUseStateAggregator =
new InUseStateAggregator() {
@Override
protected void handleInUse() {
callback.onInUse(InternalSubchannel.this);
}
@Override
protected void handleNotInUse() {
callback.onNotInUse(InternalSubchannel.this);
}
};
/**
* The to-be active transport, which is not ready yet.
*/
@Nullable
private ConnectionClientTransport pendingTransport;
/**
* The transport for new outgoing requests. Non-null only in READY state.
*/
@Nullable
private volatile ManagedClientTransport activeTransport;
private volatile ConnectivityStateInfo state = ConnectivityStateInfo.forNonError(IDLE);
private Status shutdownReason;
InternalSubchannel(List addressGroups, String authority, String userAgent,
BackoffPolicy.Provider backoffPolicyProvider,
ClientTransportFactory transportFactory, ScheduledExecutorService scheduledExecutor,
Supplier stopwatchSupplier, SynchronizationContext syncContext, Callback callback,
InternalChannelz channelz, CallTracer callsTracer, ChannelTracer channelTracer,
InternalLogId logId, ChannelLogger channelLogger,
List transportFilters) {
Preconditions.checkNotNull(addressGroups, "addressGroups");
Preconditions.checkArgument(!addressGroups.isEmpty(), "addressGroups is empty");
checkListHasNoNulls(addressGroups, "addressGroups contains null entry");
List unmodifiableAddressGroups =
Collections.unmodifiableList(new ArrayList<>(addressGroups));
this.addressGroups = unmodifiableAddressGroups;
this.addressIndex = new Index(unmodifiableAddressGroups);
this.authority = authority;
this.userAgent = userAgent;
this.backoffPolicyProvider = backoffPolicyProvider;
this.transportFactory = transportFactory;
this.scheduledExecutor = scheduledExecutor;
this.connectingTimer = stopwatchSupplier.get();
this.syncContext = syncContext;
this.callback = callback;
this.channelz = channelz;
this.callsTracer = callsTracer;
this.channelTracer = Preconditions.checkNotNull(channelTracer, "channelTracer");
this.logId = Preconditions.checkNotNull(logId, "logId");
this.channelLogger = Preconditions.checkNotNull(channelLogger, "channelLogger");
this.transportFilters = transportFilters;
}
ChannelLogger getChannelLogger() {
return channelLogger;
}
@Override
public ClientTransport obtainActiveTransport() {
ClientTransport savedTransport = activeTransport;
if (savedTransport != null) {
return savedTransport;
}
syncContext.execute(new Runnable() {
@Override
public void run() {
if (state.getState() == IDLE) {
channelLogger.log(ChannelLogLevel.INFO, "CONNECTING as requested");
gotoNonErrorState(CONNECTING);
startNewTransport();
}
}
});
return null;
}
/**
* Returns a READY transport if there is any, without trying to connect.
*/
@Nullable
ClientTransport getTransport() {
return activeTransport;
}
/**
* Returns the authority string associated with this Subchannel.
*/
String getAuthority() {
return authority;
}
private void startNewTransport() {
syncContext.throwIfNotInThisSynchronizationContext();
Preconditions.checkState(reconnectTask == null, "Should have no reconnectTask scheduled");
if (addressIndex.isAtBeginning()) {
connectingTimer.reset().start();
}
SocketAddress address = addressIndex.getCurrentAddress();
HttpConnectProxiedSocketAddress proxiedAddr = null;
if (address instanceof HttpConnectProxiedSocketAddress) {
proxiedAddr = (HttpConnectProxiedSocketAddress) address;
address = proxiedAddr.getTargetAddress();
}
Attributes currentEagAttributes = addressIndex.getCurrentEagAttributes();
String eagChannelAuthority = currentEagAttributes
.get(EquivalentAddressGroup.ATTR_AUTHORITY_OVERRIDE);
ClientTransportFactory.ClientTransportOptions options =
new ClientTransportFactory.ClientTransportOptions()
.setAuthority(eagChannelAuthority != null ? eagChannelAuthority : authority)
.setEagAttributes(currentEagAttributes)
.setUserAgent(userAgent)
.setHttpConnectProxiedSocketAddress(proxiedAddr);
TransportLogger transportLogger = new TransportLogger();
// In case the transport logs in the constructor, use the subchannel logId
transportLogger.logId = getLogId();
ConnectionClientTransport transport =
new CallTracingTransport(
transportFactory
.newClientTransport(address, options, transportLogger), callsTracer);
transportLogger.logId = transport.getLogId();
channelz.addClientSocket(transport);
pendingTransport = transport;
transports.add(transport);
Runnable runnable = transport.start(new TransportListener(transport));
if (runnable != null) {
syncContext.executeLater(runnable);
}
channelLogger.log(ChannelLogLevel.INFO, "Started transport {0}", transportLogger.logId);
}
/**
* Only called after all addresses attempted and failed (TRANSIENT_FAILURE).
* @param status the causal status when the channel begins transition to
* TRANSIENT_FAILURE.
*/
private void scheduleBackoff(final Status status) {
syncContext.throwIfNotInThisSynchronizationContext();
class EndOfCurrentBackoff implements Runnable {
@Override
public void run() {
reconnectTask = null;
channelLogger.log(ChannelLogLevel.INFO, "CONNECTING after backoff");
gotoNonErrorState(CONNECTING);
startNewTransport();
}
}
gotoState(ConnectivityStateInfo.forTransientFailure(status));
if (reconnectPolicy == null) {
reconnectPolicy = backoffPolicyProvider.get();
}
long delayNanos =
reconnectPolicy.nextBackoffNanos() - connectingTimer.elapsed(TimeUnit.NANOSECONDS);
channelLogger.log(
ChannelLogLevel.INFO,
"TRANSIENT_FAILURE ({0}). Will reconnect after {1} ns",
printShortStatus(status), delayNanos);
Preconditions.checkState(reconnectTask == null, "previous reconnectTask is not done");
reconnectTask = syncContext.schedule(
new EndOfCurrentBackoff(),
delayNanos,
TimeUnit.NANOSECONDS,
scheduledExecutor);
}
/**
* Immediately attempt to reconnect if the current state is TRANSIENT_FAILURE. Otherwise this
* method has no effect.
*/
void resetConnectBackoff() {
syncContext.execute(new Runnable() {
@Override
public void run() {
if (state.getState() != TRANSIENT_FAILURE) {
return;
}
cancelReconnectTask();
channelLogger.log(ChannelLogLevel.INFO, "CONNECTING; backoff interrupted");
gotoNonErrorState(CONNECTING);
startNewTransport();
}
});
}
private void gotoNonErrorState(final ConnectivityState newState) {
syncContext.throwIfNotInThisSynchronizationContext();
gotoState(ConnectivityStateInfo.forNonError(newState));
}
private void gotoState(final ConnectivityStateInfo newState) {
syncContext.throwIfNotInThisSynchronizationContext();
if (state.getState() != newState.getState()) {
Preconditions.checkState(state.getState() != SHUTDOWN,
"Cannot transition out of SHUTDOWN to " + newState);
state = newState;
callback.onStateChange(InternalSubchannel.this, newState);
}
}
/** Replaces the existing addresses, avoiding unnecessary reconnects. */
public void updateAddresses(final List newAddressGroups) {
Preconditions.checkNotNull(newAddressGroups, "newAddressGroups");
checkListHasNoNulls(newAddressGroups, "newAddressGroups contains null entry");
Preconditions.checkArgument(!newAddressGroups.isEmpty(), "newAddressGroups is empty");
final List newImmutableAddressGroups =
Collections.unmodifiableList(new ArrayList<>(newAddressGroups));
syncContext.execute(new Runnable() {
@Override
public void run() {
ManagedClientTransport savedTransport = null;
SocketAddress previousAddress = addressIndex.getCurrentAddress();
addressIndex.updateGroups(newImmutableAddressGroups);
addressGroups = newImmutableAddressGroups;
if (state.getState() == READY || state.getState() == CONNECTING) {
if (!addressIndex.seekTo(previousAddress)) {
// Forced to drop the connection
if (state.getState() == READY) {
savedTransport = activeTransport;
activeTransport = null;
addressIndex.reset();
gotoNonErrorState(IDLE);
} else {
pendingTransport.shutdown(
Status.UNAVAILABLE.withDescription(
"InternalSubchannel closed pending transport due to address change"));
pendingTransport = null;
addressIndex.reset();
startNewTransport();
}
}
}
if (savedTransport != null) {
if (shutdownDueToUpdateTask != null) {
// Keeping track of multiple shutdown tasks adds complexity, and shouldn't generally be
// necessary. This transport has probably already had plenty of time.
shutdownDueToUpdateTransport.shutdown(
Status.UNAVAILABLE.withDescription(
"InternalSubchannel closed transport early due to address change"));
shutdownDueToUpdateTask.cancel();
shutdownDueToUpdateTask = null;
shutdownDueToUpdateTransport = null;
}
// Avoid needless RPC failures by delaying the shutdown. See
// https://github.com/grpc/grpc-java/issues/2562
shutdownDueToUpdateTransport = savedTransport;
shutdownDueToUpdateTask = syncContext.schedule(
new Runnable() {
@Override public void run() {
ManagedClientTransport transport = shutdownDueToUpdateTransport;
shutdownDueToUpdateTask = null;
shutdownDueToUpdateTransport = null;
transport.shutdown(
Status.UNAVAILABLE.withDescription(
"InternalSubchannel closed transport due to address change"));
}
},
ManagedChannelImpl.SUBCHANNEL_SHUTDOWN_DELAY_SECONDS,
TimeUnit.SECONDS,
scheduledExecutor);
}
}
});
}
public void shutdown(final Status reason) {
syncContext.execute(new Runnable() {
@Override
public void run() {
ManagedClientTransport savedActiveTransport;
ConnectionClientTransport savedPendingTransport;
if (state.getState() == SHUTDOWN) {
return;
}
shutdownReason = reason;
savedActiveTransport = activeTransport;
savedPendingTransport = pendingTransport;
activeTransport = null;
pendingTransport = null;
gotoNonErrorState(SHUTDOWN);
addressIndex.reset();
if (transports.isEmpty()) {
handleTermination();
} // else: the callback will be run once all transports have been terminated
cancelReconnectTask();
if (shutdownDueToUpdateTask != null) {
shutdownDueToUpdateTask.cancel();
shutdownDueToUpdateTransport.shutdown(reason);
shutdownDueToUpdateTask = null;
shutdownDueToUpdateTransport = null;
}
if (savedActiveTransport != null) {
savedActiveTransport.shutdown(reason);
}
if (savedPendingTransport != null) {
savedPendingTransport.shutdown(reason);
}
}
});
}
@Override
public String toString() {
// addressGroupsCopy being a little stale is fine, just avoid calling toString with the lock
// since there may be many addresses.
return MoreObjects.toStringHelper(this)
.add("logId", logId.getId())
.add("addressGroups", addressGroups)
.toString();
}
private void handleTermination() {
syncContext.execute(new Runnable() {
@Override
public void run() {
channelLogger.log(ChannelLogLevel.INFO, "Terminated");
callback.onTerminated(InternalSubchannel.this);
}
});
}
private void handleTransportInUseState(
final ConnectionClientTransport transport, final boolean inUse) {
syncContext.execute(new Runnable() {
@Override
public void run() {
inUseStateAggregator.updateObjectInUse(transport, inUse);
}
});
}
void shutdownNow(final Status reason) {
shutdown(reason);
syncContext.execute(new Runnable() {
@Override
public void run() {
Collection transportsCopy =
new ArrayList(transports);
for (ManagedClientTransport transport : transportsCopy) {
transport.shutdownNow(reason);
}
}
});
}
List getAddressGroups() {
return addressGroups;
}
private void cancelReconnectTask() {
syncContext.throwIfNotInThisSynchronizationContext();
if (reconnectTask != null) {
reconnectTask.cancel();
reconnectTask = null;
reconnectPolicy = null;
}
}
@Override
public InternalLogId getLogId() {
return logId;
}
@Override
public ListenableFuture getStats() {
final SettableFuture channelStatsFuture = SettableFuture.create();
syncContext.execute(new Runnable() {
@Override
public void run() {
ChannelStats.Builder builder = new ChannelStats.Builder();
List addressGroupsSnapshot = addressIndex.getGroups();
List transportsSnapshot = new ArrayList(transports);
builder.setTarget(addressGroupsSnapshot.toString()).setState(getState());
builder.setSockets(transportsSnapshot);
callsTracer.updateBuilder(builder);
channelTracer.updateBuilder(builder);
channelStatsFuture.set(builder.build());
}
});
return channelStatsFuture;
}
ConnectivityState getState() {
return state.getState();
}
private static void checkListHasNoNulls(List list, String msg) {
for (Object item : list) {
Preconditions.checkNotNull(item, msg);
}
}
/** Listener for real transports. */
private class TransportListener implements ManagedClientTransport.Listener {
final ConnectionClientTransport transport;
boolean shutdownInitiated = false;
TransportListener(ConnectionClientTransport transport) {
this.transport = transport;
}
@Override
public Attributes filterTransport(Attributes attributes) {
for (ClientTransportFilter filter : transportFilters) {
attributes = Preconditions.checkNotNull(filter.transportReady(attributes),
"Filter %s returned null", filter);
}
return attributes;
}
@Override
public void transportReady() {
channelLogger.log(ChannelLogLevel.INFO, "READY");
syncContext.execute(new Runnable() {
@Override
public void run() {
reconnectPolicy = null;
if (shutdownReason != null) {
// activeTransport should have already been set to null by shutdown(). We keep it null.
Preconditions.checkState(activeTransport == null,
"Unexpected non-null activeTransport");
transport.shutdown(shutdownReason);
} else if (pendingTransport == transport) {
activeTransport = transport;
pendingTransport = null;
gotoNonErrorState(READY);
}
}
});
}
@Override
public void transportInUse(boolean inUse) {
handleTransportInUseState(transport, inUse);
}
@Override
public void transportShutdown(final Status s) {
channelLogger.log(
ChannelLogLevel.INFO, "{0} SHUTDOWN with {1}", transport.getLogId(), printShortStatus(s));
shutdownInitiated = true;
syncContext.execute(new Runnable() {
@Override
public void run() {
if (state.getState() == SHUTDOWN) {
return;
}
if (activeTransport == transport) {
activeTransport = null;
addressIndex.reset();
gotoNonErrorState(IDLE);
} else if (pendingTransport == transport) {
Preconditions.checkState(state.getState() == CONNECTING,
"Expected state is CONNECTING, actual state is %s", state.getState());
addressIndex.increment();
// Continue reconnect if there are still addresses to try.
if (!addressIndex.isValid()) {
pendingTransport = null;
addressIndex.reset();
// Initiate backoff
// Transition to TRANSIENT_FAILURE
scheduleBackoff(s);
} else {
startNewTransport();
}
}
}
});
}
@Override
public void transportTerminated() {
Preconditions.checkState(
shutdownInitiated, "transportShutdown() must be called before transportTerminated().");
channelLogger.log(ChannelLogLevel.INFO, "{0} Terminated", transport.getLogId());
channelz.removeClientSocket(transport);
handleTransportInUseState(transport, false);
for (ClientTransportFilter filter : transportFilters) {
filter.transportTerminated(transport.getAttributes());
}
syncContext.execute(new Runnable() {
@Override
public void run() {
transports.remove(transport);
if (state.getState() == SHUTDOWN && transports.isEmpty()) {
handleTermination();
}
}
});
}
}
// All methods are called in syncContext
abstract static class Callback {
/**
* Called when the subchannel is terminated, which means it's shut down and all transports
* have been terminated.
*/
@ForOverride
void onTerminated(InternalSubchannel is) { }
/**
* Called when the subchannel's connectivity state has changed.
*/
@ForOverride
void onStateChange(InternalSubchannel is, ConnectivityStateInfo newState) { }
/**
* Called when the subchannel's in-use state has changed to true, which means at least one
* transport is in use.
*/
@ForOverride
void onInUse(InternalSubchannel is) { }
/**
* Called when the subchannel's in-use state has changed to false, which means no transport is
* in use.
*/
@ForOverride
void onNotInUse(InternalSubchannel is) { }
}
@VisibleForTesting
static final class CallTracingTransport extends ForwardingConnectionClientTransport {
private final ConnectionClientTransport delegate;
private final CallTracer callTracer;
private CallTracingTransport(ConnectionClientTransport delegate, CallTracer callTracer) {
this.delegate = delegate;
this.callTracer = callTracer;
}
@Override
protected ConnectionClientTransport delegate() {
return delegate;
}
@Override
public ClientStream newStream(
MethodDescriptor method, Metadata headers, CallOptions callOptions,
ClientStreamTracer[] tracers) {
final ClientStream streamDelegate = super.newStream(method, headers, callOptions, tracers);
return new ForwardingClientStream() {
@Override
protected ClientStream delegate() {
return streamDelegate;
}
@Override
public void start(final ClientStreamListener listener) {
callTracer.reportCallStarted();
super.start(new ForwardingClientStreamListener() {
@Override
protected ClientStreamListener delegate() {
return listener;
}
@Override
public void closed(
Status status, RpcProgress rpcProgress, Metadata trailers) {
callTracer.reportCallEnded(status.isOk());
super.closed(status, rpcProgress, trailers);
}
});
}
};
}
}
/** Index as in 'i', the pointer to an entry. Not a "search index." */
@VisibleForTesting
static final class Index {
private List addressGroups;
private int groupIndex;
private int addressIndex;
public Index(List groups) {
this.addressGroups = groups;
}
public boolean isValid() {
// addressIndex will never be invalid
return groupIndex < addressGroups.size();
}
public boolean isAtBeginning() {
return groupIndex == 0 && addressIndex == 0;
}
public void increment() {
EquivalentAddressGroup group = addressGroups.get(groupIndex);
addressIndex++;
if (addressIndex >= group.getAddresses().size()) {
groupIndex++;
addressIndex = 0;
}
}
public void reset() {
groupIndex = 0;
addressIndex = 0;
}
public SocketAddress getCurrentAddress() {
return addressGroups.get(groupIndex).getAddresses().get(addressIndex);
}
public Attributes getCurrentEagAttributes() {
return addressGroups.get(groupIndex).getAttributes();
}
public List getGroups() {
return addressGroups;
}
/** Update to new groups, resetting the current index. */
public void updateGroups(List newGroups) {
addressGroups = newGroups;
reset();
}
/** Returns false if the needle was not found and the current index was left unchanged. */
public boolean seekTo(SocketAddress needle) {
for (int i = 0; i < addressGroups.size(); i++) {
EquivalentAddressGroup group = addressGroups.get(i);
int j = group.getAddresses().indexOf(needle);
if (j == -1) {
continue;
}
this.groupIndex = i;
this.addressIndex = j;
return true;
}
return false;
}
}
private String printShortStatus(Status status) {
StringBuilder buffer = new StringBuilder();
buffer.append(status.getCode());
if (status.getDescription() != null) {
buffer.append("(").append(status.getDescription()).append(")");
}
if (status.getCause() != null) {
buffer.append("[").append(status.getCause()).append("]");
}
return buffer.toString();
}
@VisibleForTesting
static final class TransportLogger extends ChannelLogger {
// Changed just after construction to break a cyclic dependency.
InternalLogId logId;
@Override
public void log(ChannelLogLevel level, String message) {
ChannelLoggerImpl.logOnly(logId, level, message);
}
@Override
public void log(ChannelLogLevel level, String messageFormat, Object... args) {
ChannelLoggerImpl.logOnly(logId, level, messageFormat, args);
}
}
}