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reactor.core.publisher.Hooks Maven / Gradle / Ivy
/*
* Copyright (c) 2011-2017 Pivotal Software Inc, 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 reactor.core.publisher;
import java.util.Collection;
import java.util.Collections;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.Objects;
import java.util.concurrent.Callable;
import java.util.function.BiFunction;
import java.util.function.Consumer;
import java.util.function.Function;
import org.reactivestreams.Publisher;
import reactor.core.Exceptions;
import reactor.core.publisher.FluxOnAssembly.AssemblySnapshot;
import reactor.util.Logger;
import reactor.util.Loggers;
import reactor.util.annotation.Nullable;
import reactor.util.context.Context;
/**
* A set of overridable lifecycle hooks that can be used for cross-cutting
* added behavior on {@link Flux}/{@link Mono} operators.
*/
public abstract class Hooks {
/**
* Add a {@link Publisher} operator interceptor for each operator created
* ({@link Flux} or {@link Mono}). The passed function is applied to the original
* operator {@link Publisher} and can return a different {@link Publisher},
* on the condition that it generically maintains the same data type as the original.
* Use of the {@link Flux}/{@link Mono} APIs is discouraged as it will recursively
* call this hook, leading to {@link StackOverflowError}.
*
* Note that sub-hooks are cumulative, but invoking this method twice with the same instance
* (or any instance that has the same `toString`) will result in only a single instance
* being applied. See {@link #onEachOperator(String, Function)} for a variant that
* allows you to name the sub-hooks (and thus replace them or remove them individually
* later on). Can be fully reset via {@link #resetOnEachOperator()}.
*
* This pointcut function cannot make use of {@link Flux}, {@link Mono} or
* {@link ParallelFlux} APIs as it would lead to a recursive call to the hook: the
* operator calls would effectively invoke onEachOperator from onEachOperator.
*
* @param onEachOperator the sub-hook: a function to intercept each operation call
* (e.g. {@code map (fn)} and {@code map(fn2)} in {@code flux.map(fn).map(fn2).subscribe()})
*
* @see #onEachOperator(String, Function)
* @see #resetOnEachOperator(String)
* @see #resetOnEachOperator()
* @see #onLastOperator(Function)
*/
public static void onEachOperator(Function, ? extends Publisher> onEachOperator) {
onEachOperator(onEachOperator.toString(), onEachOperator);
}
/**
* Add or replace a named {@link Publisher} operator interceptor for each operator created
* ({@link Flux} or {@link Mono}). The passed function is applied to the original
* operator {@link Publisher} and can return a different {@link Publisher},
* on the condition that it generically maintains the same data type as the original.
* Use of the {@link Flux}/{@link Mono} APIs is discouraged as it will recursively
* call this hook, leading to {@link StackOverflowError}.
*
* Note that sub-hooks are cumulative. Invoking this method twice with the same key will
* replace the old sub-hook with that name, but keep the execution order (eg. A-h1, B-h2,
* A-h3 will keep A-B execution order, leading to hooks h3 then h2 being executed).
* Removing a particular key using {@link #resetOnEachOperator(String)} then adding it
* back will result in the execution order changing (the later sub-hook being executed
* last). Can be fully reset via {@link #resetOnEachOperator()}.
*
* This pointcut function cannot make use of {@link Flux}, {@link Mono} or
* {@link ParallelFlux} APIs as it would lead to a recursive call to the hook: the
* operator calls would effectively invoke onEachOperator from onEachOperator.
*
* @param key the key for the sub-hook to add/replace
* @param onEachOperator the sub-hook: a function to intercept each operation call
* (e.g. {@code map (fn)} and {@code map(fn2)} in {@code flux.map(fn).map(fn2).subscribe()})
*
* @see #onEachOperator(Function)
* @see #resetOnEachOperator(String)
* @see #resetOnEachOperator()
* @see #onLastOperator(String, Function)
*/
public static void onEachOperator(String key, Function, ? extends Publisher> onEachOperator) {
Objects.requireNonNull(key, "key");
Objects.requireNonNull(onEachOperator, "onEachOperator");
log.debug("Hooking onEachOperator: {}", key);
synchronized (log) {
onEachOperatorHooks.put(key, onEachOperator);
onEachOperatorHook = createOrUpdateOpHook(onEachOperatorHooks.values());
}
}
/**
* Remove the sub-hook with key {@code key} from the onEachOperator hook. No-op if
* no such key has been registered, and equivalent to calling {@link #resetOnEachOperator()}
* if it was the last sub-hook.
*
* @param key the key of the sub-hook to remove
*/
public static void resetOnEachOperator(String key) {
Objects.requireNonNull(key, "key");
log.debug("Reset onEachOperator: {}", key);
synchronized (log) {
onEachOperatorHooks.remove(key);
onEachOperatorHook = createOrUpdateOpHook(onEachOperatorHooks.values());
}
}
/**
* Reset global "assembly" hook tracking
*/
public static void resetOnEachOperator() {
log.debug("Reset to factory defaults : onEachOperator");
synchronized (log) {
onEachOperatorHooks.clear();
onEachOperatorHook = null;
}
}
/**
* Override global error dropped strategy which by default bubble back the error.
*
* The hook is cumulative, so calling this method several times will set up the hook
* for as many consumer invocations (even if called with the same consumer instance).
*
* @param c the {@link Consumer} to apply to dropped errors
*/
public static void onErrorDropped(Consumer c) {
Objects.requireNonNull(c, "onErrorDroppedHook");
log.debug("Hooking new default : onErrorDropped");
synchronized(log) {
if (onErrorDroppedHook != null) {
@SuppressWarnings("unchecked") Consumer _c =
((Consumer)onErrorDroppedHook).andThen(c);
onErrorDroppedHook = _c;
}
else {
onErrorDroppedHook = c;
}
}
}
/**
* Add a {@link Publisher} operator interceptor for the last operator created
* in every flow ({@link Flux} or {@link Mono}). The passed function is applied
* to the original operator {@link Publisher} and can return a different {@link Publisher},
* on the condition that it generically maintains the same data type as the original.
*
* Note that sub-hooks are cumulative, but invoking this method twice with the same
* instance (or any instance that has the same `toString`) will result in only a single
* instance being applied. See {@link #onLastOperator(String, Function)} for a variant
* that allows you to name the sub-hooks (and thus replace them or remove them individually
* later on). Can be fully reset via {@link #resetOnLastOperator()}.
*
* This pointcut function cannot make use of {@link Flux}, {@link Mono} or
* {@link ParallelFlux} APIs as it would lead to a recursive call to the hook: the
* operator calls would effectively invoke onEachOperator from onEachOperator.
*
* @param onLastOperator the sub-hook: a function to intercept last operation call
* (e.g. {@code map(fn2)} in {@code flux.map(fn).map(fn2).subscribe()})
*
* @see #onLastOperator(String, Function)
* @see #resetOnLastOperator(String)
* @see #resetOnLastOperator()
* @see #onEachOperator(Function)
*/
public static void onLastOperator(Function, ? extends Publisher> onLastOperator) {
onLastOperator(onLastOperator.toString(), onLastOperator);
}
/**
* Add or replace a named {@link Publisher} operator interceptor for the last operator created
* in every flow ({@link Flux} or {@link Mono}). The passed function is applied
* to the original operator {@link Publisher} and can return a different {@link Publisher},
* on the condition that it generically maintains the same data type as the original.
* Use of the {@link Flux}/{@link Mono} APIs is discouraged as it will recursively
* call this hook, leading to {@link StackOverflowError}.
*
* Note that sub-hooks are cumulative. Invoking this method twice with the same key will
* replace the old sub-hook with that name, but keep the execution order (eg. A-h1, B-h2,
* A-h3 will keep A-B execution order, leading to hooks h3 then h2 being executed).
* Removing a particular key using {@link #resetOnLastOperator(String)} then adding it
* back will result in the execution order changing (the later sub-hook being executed
* last). Can be fully reset via {@link #resetOnLastOperator()}.
*
* This pointcut function cannot make use of {@link Flux}, {@link Mono} or
* {@link ParallelFlux} APIs as it would lead to a recursive call to the hook: the
* operator calls would effectively invoke onEachOperator from onEachOperator.
*
* @param key the key for the sub-hook to add/replace
* @param onLastOperator the sub-hook: a function to intercept last operation call
* (e.g. {@code map(fn2)} in {@code flux.map(fn).map(fn2).subscribe()})
*
* @see #onLastOperator(Function)
* @see #resetOnLastOperator(String)
* @see #resetOnLastOperator()
* @see #onEachOperator(String, Function)
*/
public static void onLastOperator(String key, Function, ? extends Publisher> onLastOperator) {
Objects.requireNonNull(key, "key");
Objects.requireNonNull(onLastOperator, "onLastOperator");
log.debug("Hooking onLastOperator: {}", key);
synchronized (log) {
onLastOperatorHooks.put(key, onLastOperator);
onLastOperatorHook = createOrUpdateOpHook(onLastOperatorHooks.values());
}
}
/**
* Remove the sub-hook with key {@code key} from the onLastOperator hook. No-op if
* no such key has been registered, and equivalent to calling {@link #resetOnLastOperator()}
* if it was the last sub-hook.
*
* @param key the key of the sub-hook to remove
*/
public static void resetOnLastOperator(String key) {
Objects.requireNonNull(key, "key");
log.debug("Reset onLastOperator: {}", key);
synchronized (log) {
onLastOperatorHooks.remove(key);
onLastOperatorHook = createOrUpdateOpHook(onLastOperatorHooks.values());
}
}
/**
* Reset global "subscriber" hook tracking
*/
public static void resetOnLastOperator() {
log.debug("Reset to factory defaults : onLastOperator");
synchronized (log) {
onLastOperatorHooks.clear();
onLastOperatorHook = null;
}
}
/**
* Override global data dropped strategy which by default logs at DEBUG level.
*
* The hook is cumulative, so calling this method several times will set up the hook
* for as many consumer invocations (even if called with the same consumer instance).
*
* @param c the {@link Consumer} to apply to data (onNext) that is dropped
* @see #onNextDroppedFail()
*/
public static void onNextDropped(Consumer c) {
Objects.requireNonNull(c, "onNextDroppedHook");
log.debug("Hooking new default : onNextDropped");
synchronized(log) {
if (onNextDroppedHook != null) {
onNextDroppedHook = onNextDroppedHook.andThen(c);
}
else {
onNextDroppedHook = c;
}
}
}
/**
* Resets {@link #resetOnNextDropped() onNextDropped hook(s)} and
* apply a strategy of throwing {@link Exceptions#failWithCancel()} instead.
*
* Use {@link #resetOnNextDropped()} to reset to the default strategy of logging.
*/
public static void onNextDroppedFail() {
log.debug("Enabling failure mode for onNextDropped");
synchronized(log) {
onNextDroppedHook = n -> {throw Exceptions.failWithCancel();};
}
}
/**
* Enable operator stack recorder that captures a declaration stack whenever an
* operator is instantiated. When errors are observed later on, they will be
* enriched with a Suppressed Exception detailing the original assembly line stack.
* Must be called before producers (e.g. Flux.map, Mono.fromCallable) are actually
* called to intercept the right stack information.
*
* This is added as a specifically-keyed sub-hook in {@link #onEachOperator(String, Function)}.
*/
public static void onOperatorDebug() {
log.debug("Enabling stacktrace debugging via onOperatorDebug");
GLOBAL_TRACE = true;
}
/**
* Reset global operator debug.
*/
public static void resetOnOperatorDebug() {
GLOBAL_TRACE = false;
}
/**
* Set the custom global error mode hook for operators that support resuming
* during an error in their {@link org.reactivestreams.Subscriber#onNext(Object)}.
*
* The hook is a {@link BiFunction} of {@link Throwable} and potentially null {@link Object}.
* If it is also a {@link java.util.function.BiPredicate}, its
* {@link java.util.function.BiPredicate#test(Object, Object) test} method should be
* used to determine if an error should be processed (matching predicate) or completely
* skipped (non-matching predicate). Typical usage, as in {@link Operators}, is to
* check if the predicate matches and fallback to {@link Operators#onOperatorError(Throwable, Context)}
* if it doesn't.
*
* @param onNextError the new {@link BiFunction} to use.
*/
public static void onNextError(BiFunction onNextError) {
Objects.requireNonNull(onNextError, "onNextError");
log.debug("Hooking new default : onNextError");
if (onNextError instanceof OnNextFailureStrategy) {
synchronized(log) {
onNextErrorHook = (OnNextFailureStrategy) onNextError;
}
}
else {
synchronized(log) {
onNextErrorHook = new OnNextFailureStrategy.LambdaOnNextErrorStrategy(onNextError);
}
}
}
/**
* Add a custom error mapping, overriding the default one. Custom mapping can be an
* accumulation of several sub-hooks each subsequently added via this method.
*
* Note that sub-hooks are cumulative, but invoking this method twice with the same
* instance (or any instance that has the same `toString`) will result in only a single
* instance being applied. See {@link #onOperatorError(String, BiFunction)} for a variant
* that allows you to name the sub-hooks (and thus replace them or remove them individually
* later on). Can be fully reset via {@link #resetOnOperatorError()}.
*
* For reference, the default mapping is to unwrap the exception and, if the second
* parameter is another exception, to add it to the first as suppressed.
*
* @param onOperatorError an operator error {@link BiFunction} mapper, returning an arbitrary exception
* given the failure and optionally some original context (data or error).
*
* @see #onOperatorError(String, BiFunction)
* @see #resetOnOperatorError(String)
* @see #resetOnOperatorError()
*/
public static void onOperatorError(BiFunction onOperatorError) {
onOperatorError(onOperatorError.toString(), onOperatorError);
}
/**
* Add or replace a named custom error mapping, overriding the default one. Custom
* mapping can be an accumulation of several sub-hooks each subsequently added via this
* method.
*
* Note that invoking this method twice with the same key will replace the old sub-hook
* with that name, but keep the execution order (eg. A-h1, B-h2, A-h3 will keep A-B
* execution order, leading to hooks h3 then h2 being executed). Removing a particular
* key using {@link #resetOnOperatorError(String)} then adding it back will result in
* the execution order changing (the later sub-hook being executed last).
* Can be fully reset via {@link #resetOnOperatorError()}.
*
* For reference, the default mapping is to unwrap the exception and, if the second
* parameter is another exception, to add it to the first as a suppressed.
*
* @param key the key for the sub-hook to add/replace
* @param onOperatorError an operator error {@link BiFunction} mapper, returning an arbitrary exception
* given the failure and optionally some original context (data or error).
*
* @see #onOperatorError(String, BiFunction)
* @see #resetOnOperatorError(String)
* @see #resetOnOperatorError()
*/
public static void onOperatorError(String key, BiFunction onOperatorError) {
Objects.requireNonNull(key, "key");
Objects.requireNonNull(onOperatorError, "onOperatorError");
log.debug("Hooking onOperatorError: {}", key);
synchronized (log) {
onOperatorErrorHooks.put(key, onOperatorError);
onOperatorErrorHook = createOrUpdateOpErrorHook(onOperatorErrorHooks.values());
}
}
/**
* Remove the sub-hook with key {@code key} from the onOperatorError hook. No-op if
* no such key has been registered, and equivalent to calling {@link #resetOnOperatorError()}
* if it was the last sub-hook.
*
* @param key the key of the sub-hook to remove
*/
public static void resetOnOperatorError(String key) {
Objects.requireNonNull(key, "key");
log.debug("Reset onOperatorError: {}", key);
synchronized (log) {
onOperatorErrorHooks.remove(key);
onOperatorErrorHook = createOrUpdateOpErrorHook(onOperatorErrorHooks.values());
}
}
/**
* Reset global operator error mapping to the default behavior.
*
* For reference, the default mapping is to unwrap the exception and, if the second
* parameter is another exception, to add it to the first as a suppressed.
*/
public static void resetOnOperatorError() {
log.debug("Reset to factory defaults : onOperatorError");
synchronized (log) {
onOperatorErrorHooks.clear();
onOperatorErrorHook = null;
}
}
/**
* Reset global error dropped strategy to bubbling back the error.
*/
public static void resetOnErrorDropped() {
log.debug("Reset to factory defaults : onErrorDropped");
synchronized (log) {
onErrorDroppedHook = null;
}
}
/**
* Reset global data dropped strategy to throwing via {@link
* reactor.core.Exceptions#failWithCancel()}
*/
public static void resetOnNextDropped() {
log.debug("Reset to factory defaults : onNextDropped");
synchronized (log) {
onNextDroppedHook = null;
}
}
/**
* Reset global onNext error handling strategy to terminating the sequence with
* an onError and cancelling upstream ({@link OnNextFailureStrategy#STOP}).
*/
public static void resetOnNextError() {
log.debug("Reset to factory defaults : onNextError");
synchronized (log) {
onNextErrorHook = null;
}
}
@Nullable
@SuppressWarnings("unchecked")
static Function createOrUpdateOpHook(Collection, ? extends Publisher>> hooks) {
Function composite = null;
for (Function, ? extends Publisher> function : hooks) {
Function op = (Function) function;
if (composite != null) {
composite = composite.andThen(op);
}
else {
composite = (Function) op;
}
}
return composite;
}
@Nullable
static BiFunction createOrUpdateOpErrorHook(Collection> hooks) {
BiFunction composite = null;
for (BiFunction function : hooks) {
if (composite != null) {
BiFunction ff = composite;
composite = (e, data) -> function.apply(ff.apply(e, data), data);
}
else {
composite = function;
}
}
return composite;
}
//Hooks that are transformative
static volatile Function onEachOperatorHook;
static volatile Function onLastOperatorHook;
static volatile BiFunction onOperatorErrorHook;
//Hooks that are just callbacks
static volatile Consumer onErrorDroppedHook;
static volatile Consumer onNextDroppedHook;
//Special hook that is between the two (strategy can be transformative, but not named)
static volatile OnNextFailureStrategy onNextErrorHook;
//For transformative hooks, allow to name them, keep track in an internal Map that retains insertion order
//internal use only as it relies on external synchronization
private static final LinkedHashMap, ? extends Publisher>> onEachOperatorHooks;
private static final LinkedHashMap, ? extends Publisher>> onLastOperatorHooks;
private static final LinkedHashMap> onOperatorErrorHooks;
//Immutable views on hook trackers, for testing purpose
static final Map, ? extends Publisher>> getOnEachOperatorHooks() {
return Collections.unmodifiableMap(onEachOperatorHooks);
}
static final Map, ? extends Publisher>> getOnLastOperatorHooks() {
return Collections.unmodifiableMap(onLastOperatorHooks);
}
static final Map> getOnOperatorErrorHooks() {
return Collections.unmodifiableMap(onOperatorErrorHooks);
}
static final Logger log = Loggers.getLogger(Hooks.class);
/**
* A key that can be used to store a sequence-specific {@link Hooks#onErrorDropped(Consumer)}
* hook in a {@link Context}, as a {@link Consumer Consumer<Throwable>}.
*/
static final String KEY_ON_ERROR_DROPPED = "reactor.onErrorDropped.local";
/**
* A key that can be used to store a sequence-specific {@link Hooks#onNextDropped(Consumer)}
* hook in a {@link Context}, as a {@link Consumer Consumer<Object>}.
*/
static final String KEY_ON_NEXT_DROPPED = "reactor.onNextDropped.local";
/**
* A key that can be used to store a sequence-specific {@link Hooks#onOperatorError(BiFunction)}
* hook in a {@link Context}, as a {@link BiFunction BiFunction<Throwable, Object, Throwable>}.
*/
static final String KEY_ON_OPERATOR_ERROR = "reactor.onOperatorError.local";
/**
* A key that can be used to store a sequence-specific onDiscard(Consumer)
* hook in a {@link Context}, as a {@link Consumer Consumer<Object>}.
*/
static final String KEY_ON_DISCARD = "reactor.onDiscard.local";
/**
* A key that can be used to store a sequence-specific {@link Hooks#onOperatorError(BiFunction)}
* hook THAT IS ONLY APPLIED TO Operators{@link Operators#onRejectedExecution(Throwable, Context) onRejectedExecution}
* in a {@link Context}, as a {@link BiFunction BiFunction<Throwable, Object, Throwable>}.
*/
static final String KEY_ON_REJECTED_EXECUTION = "reactor.onRejectedExecution.local";
static boolean GLOBAL_TRACE =
Boolean.parseBoolean(System.getProperty("reactor.trace.operatorStacktrace",
"false"));
static {
onEachOperatorHooks = new LinkedHashMap<>(1);
onLastOperatorHooks = new LinkedHashMap<>(1);
onOperatorErrorHooks = new LinkedHashMap<>(1);
}
Hooks() {
}
static > Publisher addAssemblyInfo(P publisher, AssemblySnapshot stacktrace) {
if (publisher instanceof Callable) {
if (publisher instanceof Mono) {
return new MonoCallableOnAssembly<>((Mono) publisher, stacktrace);
}
return new FluxCallableOnAssembly<>((Flux) publisher, stacktrace);
}
if (publisher instanceof Mono) {
return new MonoOnAssembly<>((Mono) publisher, stacktrace);
}
if (publisher instanceof ParallelFlux) {
return new ParallelFluxOnAssembly<>((ParallelFlux) publisher, stacktrace);
}
if (publisher instanceof ConnectableFlux) {
return new ConnectableFluxOnAssembly<>((ConnectableFlux) publisher, stacktrace);
}
return new FluxOnAssembly<>((Flux) publisher, stacktrace);
}
}
