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etcd3 java client and utilities
/*
* Copyright 2017, 2018 IBM Corp. All Rights Reserved.
*
* 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 com.ibm.etcd.client;
import static com.google.common.util.concurrent.MoreExecutors.directExecutor;
import static java.util.concurrent.TimeUnit.MILLISECONDS;
import java.lang.reflect.Proxy;
import java.net.ConnectException;
import java.net.NoRouteToHostException;
import java.util.ArrayDeque;
import java.util.Queue;
import java.util.concurrent.CancellationException;
import java.util.concurrent.ConcurrentLinkedQueue;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.Executor;
import java.util.concurrent.Future;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.ThreadLocalRandom;
import java.util.concurrent.TimeoutException;
import java.util.concurrent.locks.LockSupport;
import java.util.function.Function;
import java.util.function.Supplier;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import com.google.common.base.Preconditions;
import com.google.common.base.Predicate;
import com.google.common.base.Predicates;
import com.google.common.base.Throwables;
import com.google.common.util.concurrent.Futures;
import com.google.common.util.concurrent.ListenableFuture;
import com.google.common.util.concurrent.ListeningScheduledExecutorService;
import com.google.common.util.concurrent.MoreExecutors;
import com.google.common.util.concurrent.RateLimiter;
import com.google.common.util.concurrent.SettableFuture;
import com.google.common.util.concurrent.Uninterruptibles;
import io.grpc.CallCredentials;
import io.grpc.CallOptions;
import io.grpc.Deadline;
import io.grpc.ManagedChannel;
import io.grpc.MethodDescriptor;
import io.grpc.Status;
import io.grpc.Status.Code;
import io.grpc.stub.ClientCallStreamObserver;
import io.grpc.stub.ClientCalls;
import io.grpc.stub.ClientResponseObserver;
import io.grpc.stub.StreamObserver;
import io.netty.util.concurrent.OrderedEventExecutor;
/**
* grpc client support - non-etcd specific
*
*/
public class GrpcClient {
private static final Logger logger = LoggerFactory.getLogger(GrpcClient.class);
private final long defaultTimeoutMs;
public interface AuthProvider {
/**
* Called from a synchronized context
*/
CallCredentials refreshCredentials();
default CallCredentials refreshCredentials(Throwable trigger) {
return refreshCredentials();
}
/**
* Not called from a synchronized context
*/
boolean requiresReauth(Throwable t);
}
private static final AuthProvider NO_AUTH = new AuthProvider() {
@Override public boolean requiresReauth(Throwable t) { return false; }
@Override public CallCredentials refreshCredentials() { throw new IllegalStateException(); }
};
private final AuthProvider authProvider;
private final ManagedChannel channel;
protected final ListeningScheduledExecutorService ses;
protected final Executor userExecutor;
// returns true if the current thread belongs to the internal executor
protected final Condition isEventThread;
// if true (default) all calls to etcd will be made via the shared
// internal executor (grpc netty eventloopgroup).
// this ensures better concentration of ThreadLocal bytebuf caches
// which are allocated on this path
protected final boolean sendViaEventLoop;
// limit overall rate of immediate retries after failed calls to 1/sec,
// to avoid excessive requests when there are connection problems
protected final RateLimiter immediateRetryLimiter = RateLimiter.create(1.0);
// modified only by reauthenticate() method
private CallOptions callOptions = CallOptions.DEFAULT; // volatile tbd - lazy probably ok
/**
* @deprecated use other constructor
*/
@Deprecated
public GrpcClient(ManagedChannel channel,
Predicate reauthRequired,
Supplier credsSupplier,
ScheduledExecutorService executor, Condition isEventThread,
Executor userExecutor, boolean sendViaEventLoop, long defaultTimeoutMs) {
this(channel, reauthRequired == null ? null : new AuthProvider() {
{
Preconditions.checkArgument((reauthRequired == null) == (credsSupplier == null),
"must supply both or neither reauth and creds");
}
@Override
public boolean requiresReauth(Throwable t) {
return reauthRequired.apply(t);
}
@Override
public CallCredentials refreshCredentials() {
return credsSupplier.get();
}
}, executor, isEventThread, userExecutor, sendViaEventLoop, defaultTimeoutMs);
}
//TODO whether some/all of the channel construction is moved in here
public GrpcClient(ManagedChannel channel, AuthProvider authProvider,
ScheduledExecutorService executor, Condition isEventThread,
Executor userExecutor, boolean sendViaEventLoop, long defaultTimeoutMs) {
this.channel = Preconditions.checkNotNull(channel, "channel");
this.authProvider = authProvider != null ? authProvider : NO_AUTH;
this.ses = MoreExecutors.listeningDecorator(executor);
this.isEventThread = Preconditions.checkNotNull(isEventThread, "isEventThread");
this.userExecutor = Preconditions.checkNotNull(userExecutor, "userExecutor");
this.sendViaEventLoop = sendViaEventLoop;
this.defaultTimeoutMs = defaultTimeoutMs;
}
/**
* @deprecated use {@link #getInternalExecutor()}
*/
@Deprecated
public ScheduledExecutorService getExecutor() {
return ses;
}
/**
* Care should be taken not to use this executor for any blocking
* or CPU intensive tasks.
*/
public ScheduledExecutorService getInternalExecutor() {
return ses;
}
public Executor getResponseExecutor() {
return userExecutor;
}
public void authenticateNow() {
assert authProvider != NO_AUTH;
reauthenticate(getCallOptions(), null);
}
protected CallOptions getCallOptions() {
return callOptions;
}
static final RetryDecision IDEMP = (t,r) -> {
Status status = Status.fromThrowable(t);
Code code = status != null ? status.getCode() : null;
return code == Code.UNAVAILABLE
|| code == Code.DEADLINE_EXCEEDED
|| (code == Code.UNKNOWN
&& status.getDescription() != null
&& status.getDescription().startsWith("Channel closed"));
};
static final RetryDecision NON_IDEMP = (t,r) -> {
Status status = Status.fromThrowable(t);
Code code = status != null ? status.getCode() : null;
return (code == Code.UNAVAILABLE && isConnectException(t))
|| (code == Code.UNKNOWN && status.getDescription() != null
// This *should* have RESOURCE_EXHAUSTED code, but it doesn't
// seem to come through that way, at least on etcd versions up to 3.3.17
&& status.getDescription().contains("etcdserver: too many requests"));
};
@SuppressWarnings("unchecked")
public static RetryDecision retryDecision(boolean idempotent) {
return (RetryDecision) (idempotent ? IDEMP : NON_IDEMP);
}
public ListenableFuture call(MethodDescriptor method,
ReqT request, boolean idempotent) {
return call(method, null, request, null, retryDecision(idempotent),
0, false, false, null, 0L);
}
public ListenableFuture call(MethodDescriptor method,
ReqT request, boolean idempotent, long timeoutMillis, Executor executor) {
return call(method, null, request, executor, retryDecision(idempotent),
0, false, false, null, timeoutMillis);
}
//TODO probably move this
public static interface RetryDecision {
boolean retry(Throwable t, ReqT request);
}
public ListenableFuture call(MethodDescriptor method, Condition precondition,
ReqT request, Executor executor, RetryDecision retry, boolean backoff,
Deadline deadline, long timeoutMs) {
return call(method, precondition, request, executor, retry, 0, false, backoff, deadline, timeoutMs);
}
// deadline is for entire request (including retry pauses),
// timeout is per-attempt and 0 means not specified
private ListenableFuture call(MethodDescriptor method,
Condition precondition, ReqT request, Executor executor, RetryDecision retry,
int attempt, boolean afterReauth, boolean backoff, Deadline deadline, long timeoutMs) {
if (precondition != null && !precondition.satisfied()) {
return failInExecutor(new CancellationException("precondition false"), executor);
}
//TODO(maybe) in delay case (attempt > 1), if "session" is inactive,
// skip attempt (and don't increment attempt #)
final CallOptions baseCallOpts = getCallOptions();
CallOptions callOpts = deadline != null ? baseCallOpts.withDeadline(deadline) : baseCallOpts;
if (executor != null) {
callOpts = callOpts.withExecutor(executor);
}
return Futures.catchingAsync(fuCall(method, request, callOpts, timeoutMs), Exception.class, t -> {
// first cases: determine if we fail immediately
if ((!backoff && attempt > 0) || (deadline != null && deadline.isExpired())) {
// multiple retries disabled or deadline expired
return Futures.immediateFailedFuture(t);
}
boolean reauth = false;
if (authProvider.requiresReauth(t)) {
if (afterReauth) {
// if we have an auth failure immediately following a reauth, give up
// (important to avoid infinite loop of auth failures)
return Futures.immediateFailedFuture(t);
}
reauthenticate(baseCallOpts, t);
reauth = true;
} else if (!retry.retry(t, request)) {
// retry predicate says no (non retryable request and/or error)
return Futures.immediateFailedFuture(t);
}
// second case: immediate retry (first failure or after auth failure + reauth)
if (reauth || attempt == 0 && immediateRetryLimiter.tryAcquire()) {
return call(method, precondition, request, executor, retry,
reauth ? attempt : 1, reauth, backoff, deadline, timeoutMs);
}
int nextAttempt = attempt <= 1 ? 2 : attempt + 1; // skip attempt if we were rate-limited
// final case: retry after back-off delay
long delayMs = delayAfterFailureMs(nextAttempt);
if (deadline != null && deadline.timeRemaining(MILLISECONDS) < delayMs) {
return Futures.immediateFailedFuture(t);
}
return Futures.scheduleAsync(() -> call(method, precondition, request, executor, retry,
nextAttempt, false, backoff, deadline, timeoutMs), delayMs, MILLISECONDS, ses);
}, executor != null ? executor : directExecutor());
}
/**
* @param failedAttemptNumber number of the attempt which just failed, 1-based
*/
static long delayAfterFailureMs(int failedAttemptNumber) {
// backoff delay pattern: 0, [500ms - 1sec), 2sec, 4sec, 8sec, 8sec, ... (jitter after first retry)
if (failedAttemptNumber <= 1) {
return 0L;
}
return failedAttemptNumber == 2
? 500L + ThreadLocalRandom.current().nextLong(500L)
: (2000L << Math.min(failedAttemptNumber - 3, 2));
}
protected static ListenableFuture failInExecutor(Throwable t, Executor executor) {
if (executor == null) {
return Futures.immediateFailedFuture(t);
}
SettableFuture lfut = SettableFuture.create();
executor.execute(() -> lfut.setException(t));
return lfut;
}
//TODO(maybe) for retriable RPCs consider fail-fast first timeout and longer retry timeout
protected ListenableFuture fuCall(MethodDescriptor method, ReqT request,
CallOptions callOptions, long timeoutMs) {
if (timeoutMs <= 0L) {
timeoutMs = defaultTimeoutMs;
}
if (timeoutMs > 0L) {
Deadline deadline = callOptions.getDeadline();
Deadline timeoutDeadline = Deadline.after(timeoutMs, MILLISECONDS);
if (deadline == null || timeoutDeadline.isBefore(deadline)) {
callOptions = callOptions.withDeadline(timeoutDeadline);
} else if (deadline.isExpired()) {
return Futures.immediateFailedFuture(
Status.DEADLINE_EXCEEDED.asRuntimeException());
}
}
final CallOptions finalCallOpts = callOptions;
return sendViaEventLoop && !isEventThread.satisfied()
? Futures.submitAsync(() -> fuCall(method, request, finalCallOpts), ses)
: fuCall(method, request, finalCallOpts);
}
protected ListenableFuture fuCall(MethodDescriptor method, ReqT request,
CallOptions callOptions) {
return ClientCalls.futureUnaryCall(channel.newCall(method, callOptions), request);
}
protected boolean retryableStreamError(Throwable error) {
return (Status.fromThrowable(error).getCode() != Code.INVALID_ARGUMENT
&& !causedBy(error, Error.class));
}
/**
* @return true if reauthentication was required and attempted
*/
protected boolean reauthIfRequired(Throwable error, CallOptions callOpts) {
if (authProvider.requiresReauth(error)) {
reauthenticate(callOpts, error);
return true;
}
return false;
}
public static boolean isConnectException(Throwable t) {
return causedBy(t, ConnectException.class) || causedBy(t, NoRouteToHostException.class);
}
public static Code codeFromThrowable(Throwable t) {
return Status.fromThrowable(t).getCode(); // fromThrowable won't return null
}
private void reauthenticate(CallOptions failedOpts, Throwable authFailure) {
// assert name != null && password != null;
if (getCallOptions() == failedOpts) { // obj identity comparison intentional
synchronized (this) {
CallOptions callOpts = getCallOptions();
if (callOpts == failedOpts) {
callOptions = callOpts.withCallCredentials(
authProvider.refreshCredentials(authFailure));
}
}
}
}
public StreamObserver callStream(MethodDescriptor method,
ResilientResponseObserver respStream) {
return callStream(method, respStream, null);
}
public StreamObserver callStream(MethodDescriptor method,
ResilientResponseObserver respStream, Executor responseExecutor) {
// must explicitly auth in stream case to ensure unauthenticated version isn't used
if (authProvider != NO_AUTH && getCallOptions() == CallOptions.DEFAULT) {
// This will update callOptions with new CallCredentials prior to opening the stream
authenticateNow();
}
return new ResilientBiDiStream<>(method, respStream, responseExecutor).start();
}
public static interface ResilientResponseObserver extends StreamObserver {
/**
* Called once initially, and once after each {@link #onReplaced(StreamObserver)},
* to indicate the corresponding (sub) stream is successfully established
*/
public void onEstablished();
/**
* Indicates the underlying stream failed and will be re-established. There is
* no guarantee that any requests sent to the current request stream have
* been delivered, the provided stream should be used in its place to send
* all subsequent requests, including re-submissions if necessary. Any subsequent
* {@link #onEstablished()} or {@link #onNext(Object)} calls received will
* be responses from this new stream, it's guaranteed that there will
* be no more from the prior stream.
*
* @param newStreamRequestObserver
*/
public void onReplaced(StreamObserver newStreamRequestObserver);
}
final class ResilientBiDiStream {
private final MethodDescriptor method;
private final ResilientResponseObserver respStream;
private final Executor responseExecutor;
// null if !sendViaEventLoop
private final Executor requestExecutor;
// accessed only from response thread and retry task scheduled
// from the onError message (prior to stream being reestablished)
private CallOptions sentCallOptions;
private int errCounter = 0;
// provided to user, buffers and wraps real req stream when active.
// field accessed only from response thread
private RequestSubStream userReqStream;
// finished reflects *user* closing stream via terminal method (not incoming stream closure)
// error == null indicates complete versus failed when finished == true
// modified only by response thread
private boolean finished;
private Throwable error;
private boolean lastAuthFailed;
/**
*
* @param method
* @param respStream
* @param responseExecutor
*/
public ResilientBiDiStream(MethodDescriptor method,
ResilientResponseObserver respStream,
Executor responseExecutor) {
this.method = method;
this.respStream = respStream;
this.responseExecutor = serialized(responseExecutor != null
? responseExecutor : userExecutor);
this.requestExecutor = sendViaEventLoop ? serialized(ses) : null;
}
// must only be called once - enforcement logic omitted since private
StreamObserver start() {
RequestSubStream firstStream = new RequestSubStream();
userReqStream = firstStream;
responseExecutor.execute(this::refreshBackingStream);
return firstStream;
}
class RequestSubStream implements StreamObserver {
// lifecycle: null -> real stream -> EMPTY_STREAM
private volatile StreamObserver grpcReqStream; // only modified by response thread
// grpcReqStream non-null => preConnectBuffer null
private Queue preConnectBuffer;
// called by user thread
@Override
public void onNext(ReqT value) {
if (finished) {
return; // illegal usage
}
StreamObserver rs = grpcReqStream;
if (rs == null) synchronized (this) {
rs = grpcReqStream;
if (rs == null) {
if (preConnectBuffer == null) {
preConnectBuffer = new ArrayDeque<>(8); // bounded TBD
}
preConnectBuffer.add(value);
return;
}
}
if (requestExecutor == null) {
sendOnNext(rs, value); // (***)
} else {
final StreamObserver rsFinal = rs;
requestExecutor.execute(() -> sendOnNext(rsFinal, value));
}
}
private void sendOnNext(StreamObserver reqStream, ReqT value) {
try {
reqStream.onNext(value);
} catch (IllegalStateException ise) {
// this is possible and ok if the stream was already closed
if (grpcReqStream != emptyStream()) throw ise;
}
}
// called by user thread
@Override
public void onError(Throwable t) {
onFinish(t);
}
// called by user thread
@Override
public void onCompleted() {
onFinish(null);
}
// called from response thread
boolean established(StreamObserver stream) {
StreamObserver curStream = grpcReqStream;
if (curStream == null) synchronized (this) {
Queue pcb = preConnectBuffer;
if (pcb != null) {
for (ReqT req; (req = pcb.poll()) != null;) {
stream.onNext(req);
}
preConnectBuffer = null;
}
initialReqStream = null;
if (finished) {
grpcReqStream = emptyStream();
} else {
grpcReqStream = stream;
return true;
}
} else if (stream == curStream) {
return false;
}
// here either finished or it's an unexpected new stream
if (!finished) {
logger.info("Closing unexpected new stream of method "
+ method.getFullMethodName());
}
closeStream(stream, error);
return false;
}
boolean isEstablished() {
return grpcReqStream != null;
}
// called from grpc response thread
void discard(Throwable err) {
StreamObserver curStream = grpcReqStream, empty = emptyStream();
if (curStream == empty) {
return;
}
if (curStream == null) synchronized (this) {
grpcReqStream = empty;
preConnectBuffer = null;
} else {
//TODO this *could* overlap with an in-progress
// onNext (***) above in the sendViaEventLoop == false case, but unlikely
// For now, delay sending the close to further minimize the chance
close(err, false);
}
}
// called from grpc response thread
void close(Throwable err, boolean fromUser) {
StreamObserver curStream = grpcReqStream, empty = emptyStream();
if (curStream == null || curStream == empty) {
return;
}
grpcReqStream = empty;
//assert preConnectBuffer == null;
if (fromUser) {
closeStream(curStream, err);
} else {
Runnable closeTask = () -> closeStream(curStream, err);
if (requestExecutor != null) {
requestExecutor.execute(closeTask);
} else {
ses.schedule(closeTask, 400, MILLISECONDS);
}
}
}
}
// called by user thread
private void onFinish(Throwable err) {
if (finished) {
return; // shouldn't be called more than once anyhow
}
responseExecutor.execute(() -> {
if(finished) {
return;
}
// Don't treat this as final if authentication
// is enabled and the error reflects that reauth
// is required - instead just cancel the "current"
// stream which will cause the top-level stream
// to be refreshed after a reauth is done
if (err == null || !authProvider.requiresReauth(err)) {
error = err;
finished = true;
}
userReqStream.close(err, true);
});
}
/*
* We assume the caller (grpc) abides by StreamObserver contract
*/
private final StreamObserver respWrapper = new ClientResponseObserver() {
@Override
public void beforeStart(ClientCallStreamObserver rs) {
rs.setOnReadyHandler(() -> {
// called from grpc response thread
if (rs.isReady()) {
errCounter = 0;
boolean notify = userReqStream.established(rs);
if (notify) {
respStream.onEstablished();
}
}
});
}
// called from grpc response thread
@Override
public void onNext(RespT value) {
lastAuthFailed = false;
respStream.onNext(value);
}
// called from grpc response thread
@Override
public void onError(Throwable t) {
boolean finalError, reauthed = false;
if (finished) {
finalError = true;
} else {
reauthed = !lastAuthFailed && reauthIfRequired(t, sentCallOptions);
finalError = !reauthed && !retryableStreamError(t);
}
lastAuthFailed = reauthed;
if (!finalError) {
int errCount = -1;
String msg;
if (reauthed) {
msg = "Reauthenticating after auth error (likely expiry) on underlying"
+ " stream of method " + method.getFullMethodName();
} else {
errCount = ++errCounter;
msg = "Retryable onError #" + errCount
+ " on underlying stream of method " + method.getFullMethodName();
}
if (logger.isDebugEnabled()) {
logger.info(msg, t);
} else {
if (reauthed) {
t = Throwables.getRootCause(t);
}
logger.info(msg + ": " + t.getClass().getName() + ": " + t.getMessage());
}
RequestSubStream userStreamBefore = userReqStream;
if (userStreamBefore.isEstablished()) {
userReqStream = new RequestSubStream();
userStreamBefore.discard(null);
// must call onReplaced prior to refreshing the stream, otherwise
// the response observer may be called with responses from the
// new stream prior to onReplaced returning
respStream.onReplaced(userReqStream);
} else if (initialReqStream != null) {
// else no need to replace user stream, but cancel outbound stream
initialReqStream.onError(t);
initialReqStream = null;
}
// re-attempt immediately after reauthentication
if (reauthed || (errCount <= 1 && immediateRetryLimiter.tryAcquire())) {
refreshBackingStream();
} else {
// delay stream retry using backoff/jitter strategy
ses.schedule(ResilientBiDiStream.this::refreshBackingStream,
// skip attempt in rate-limited case (errCount <=1)
delayAfterFailureMs(errCount <= 2 ? 2 : errCount), MILLISECONDS);
}
} else {
sentCallOptions = null;
userReqStream.discard(t);
respStream.onError(t);
}
}
// called from grpc response thread
@Override
public void onCompleted() {
lastAuthFailed = false;
if (!finished) {
logger.warn("Unexpected onCompleted received"
+ " for stream of method " + method.getFullMethodName());
//TODO(maybe) reestablish stream in this case?
}
sentCallOptions = null;
userReqStream.discard(null);
respStream.onCompleted();
}
};
// called only from:
// - grpc response thread
// - scheduled retry (no active stream)
private void refreshBackingStream() {
if (finished) {
return;
}
CallOptions callOpts = getCallOptions();
sentCallOptions = callOpts;
callOpts = callOpts.withExecutor(responseExecutor);
initialReqStream = ClientCalls.asyncBidiStreamingCall(
channel.newCall(method, callOpts), respWrapper);
}
// this is just stored to cancel if the call fails before
// being established
private StreamObserver initialReqStream;
}
// ------- utilities
public final T waitForCall(Function> asyncCall) {
return waitFor(asyncCall, userExecutor);
}
public static T waitFor(Future fut) {
return waitFor(fut, -1L);
}
public static T waitFor(Future fut, long timeoutMillis) {
try {
return timeoutMillis < 0L ? fut.get() : fut.get(timeoutMillis, MILLISECONDS);
} catch (InterruptedException|CancellationException e) {
fut.cancel(true);
if (e instanceof InterruptedException) {
Thread.currentThread().interrupt();
}
throw Status.CANCELLED.withCause(e).asRuntimeException();
} catch (ExecutionException ee) {
throw Status.fromThrowable(ee.getCause()).asRuntimeException();
} catch (TimeoutException te) {
fut.cancel(true);
throw Status.DEADLINE_EXCEEDED.withCause(te)
.withDescription("local timeout of " + timeoutMillis + "ms exceeded")
.asRuntimeException();
} catch (RuntimeException rte) {
fut.cancel(true);
throw Status.fromThrowable(rte).asRuntimeException();
}
}
public static T waitFor(Function> asyncCall) {
return waitFor(asyncCall, null);
}
public static T waitFor(Function> asyncCall,
Executor fallbackExecutor) {
ThreadlessExecutor exec = new ThreadlessExecutor(fallbackExecutor);
try {
Future fut = asyncCall.apply(exec);
while (!fut.isDone()) try {
exec.waitAndDrain();
} catch (InterruptedException ie) {
if (!fut.isDone()) try {
fut.cancel(true);
exec.waitAndDrain();
} catch (InterruptedException ie2) { }
Thread.currentThread().interrupt();
throw Status.CANCELLED.withCause(ie).asRuntimeException();
}
try {
return Uninterruptibles.getUninterruptibly(fut);
} catch (CancellationException e) {
throw Status.CANCELLED.withCause(e).asRuntimeException();
} catch (ExecutionException ee) {
throw Status.fromThrowable(ee.getCause()).asRuntimeException();
} catch (RuntimeException rte) {
fut.cancel(true);
throw Status.fromThrowable(rte).asRuntimeException();
}
} finally {
// This is necessary to ensure the call is closed and doesn't leak resources
exec.shutdown();
}
}
protected static void closeStream(StreamObserver stream, Throwable err) {
if (err == null) {
stream.onCompleted();
} else {
stream.onError(err);
}
}
@SuppressWarnings("rawtypes")
private static final StreamObserver EMPTY_STREAM = new StreamObserver() {
@Override public void onCompleted() {}
@Override public void onError(Throwable t) {}
@Override public void onNext(Object value) {}
};
@SuppressWarnings("unchecked")
protected static StreamObserver emptyStream() {
return (StreamObserver) EMPTY_STREAM;
}
protected static Predicate constantPredicate(boolean val) {
return val ? Predicates.alwaysTrue() : Predicates.alwaysFalse();
}
protected static boolean contains(String str, String subStr) {
return str != null && str.contains(subStr);
}
public static boolean causedBy(Throwable t, Class exClass) {
return t != null && (exClass.isAssignableFrom(t.getClass())
|| causedBy(t.getCause(), exClass));
}
@SuppressWarnings("unchecked")
public static I sentinel(Class intface) {
return (I) Proxy.newProxyInstance(intface.getClassLoader(),
new Class[] { intface }, (p,m,a) -> {
switch (m.getName()) {
case "toString": return "SENTINEL";
case "hashCode": return System.identityHashCode(p);
case "equals": return a[0] == p;
default: throw new IllegalStateException("attempt to invoke sentinel");
}
});
}
public static Executor serialized(Executor parent) {
return serialized(parent, 0);
}
private static final Class GSE_CLASS
= MoreExecutors.newSequentialExecutor(directExecutor()).getClass();
public static Executor serialized(Executor parent, int bufferSize) {
return parent instanceof SerializingExecutor
|| parent instanceof io.grpc.internal.SerializingExecutor
|| parent instanceof OrderedEventExecutor
|| parent.getClass() == GSE_CLASS
? parent : new SerializingExecutor(parent, bufferSize);
}
/**
* Equivalent to the executor used in grpc ClientCalls class for blocking calls.
*/
@SuppressWarnings("serial")
private static final class ThreadlessExecutor extends ConcurrentLinkedQueue
implements Executor {
private static final Logger logger = LoggerFactory.getLogger(ThreadlessExecutor.class);
private static final Thread SHUTDOWN = new Thread(); // sentinel
private final Executor fallbackExecutor;
private volatile Thread waiter;
ThreadlessExecutor(Executor fallbackExecutor) {
this.fallbackExecutor = fallbackExecutor;
}
public void waitAndDrain() throws InterruptedException {
final Thread currentThread = Thread.currentThread();
throwIfInterrupted(currentThread);
Runnable runnable = poll();
if (runnable == null) {
waiter = currentThread;
try {
while ((runnable = poll()) == null) {
LockSupport.park(this);
throwIfInterrupted(currentThread);
}
} finally {
waiter = null;
}
}
do {
runQuietly(runnable);
} while ((runnable = poll()) != null);
}
/**
* Called after final call to {@link #waitAndDrain()}, from same thread.
*/
public void shutdown() {
waiter = SHUTDOWN;
// There should usually be nothing to run here
for (Runnable runnable; (runnable = poll()) != null;) {
runQuietly(runnable);
}
}
private static void runQuietly(Runnable runnable) {
try {
runnable.run();
} catch (Throwable t) {
Throwables.throwIfInstanceOf(t, Error.class);
logger.warn("Runnable threw exception", t);
}
}
private static void throwIfInterrupted(Thread currentThread) throws InterruptedException {
if (currentThread.isInterrupted()) {
throw new InterruptedException();
}
}
@Override
public void execute(Runnable runnable) {
add(runnable);
Thread waiter = this.waiter;
if (waiter != SHUTDOWN) {
LockSupport.unpark(waiter); // no-op if null
} else if (remove(runnable)) {
// Make sure the runnable gets run one way or another,
// to ensure that resources are closed (this is a grpc-java
// race condition bug in versions 1.26.0 - 1.30.0).
// Note the Runnable will itself always be a SeralizingExecutor,
// so there's no need to consider additional synchronization here
if (fallbackExecutor != null) {
fallbackExecutor.execute(runnable);
} else {
runQuietly(runnable);
}
}
}
}
}