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/*
 * Copyright 2022 VMware, Inc.
 *
 * 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
 *
 * https://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.micrometer.observation;

import io.micrometer.common.KeyValue;
import io.micrometer.common.KeyValues;
import io.micrometer.common.lang.NonNull;
import io.micrometer.common.lang.Nullable;
import io.micrometer.common.util.internal.logging.InternalLoggerFactory;

import java.util.LinkedHashMap;
import java.util.Map;
import java.util.concurrent.Callable;
import java.util.concurrent.ConcurrentHashMap;
import java.util.function.Function;
import java.util.function.Supplier;
import java.util.stream.Collectors;

/**
 * An act of viewing or noticing a fact or an occurrence for some scientific or other
 * special purpose (According to dictionary.com).
 *
 * You can wrap an operation within your code in an {@link Observation} so that actions
 * can take place within the lifecycle of that observation via the
 * {@link ObservationHandler}.
 *
 * According to what is configured the actions can be e.g. taking measurements via
 * {@code Timer}, creating spans for distributed tracing, correlating logs or just logging
 * out additional information. You instrument your code once with an {@link Observation}
 * but you can get as many benefits out of it as many {@link ObservationHandler} you have.
 *
 * @author Jonatan Ivanov
 * @author Tommy Ludwig
 * @author Marcin Grzejszczak
 * @author Yanming Zhou
 * @since 1.10.0
 */
public interface Observation extends ObservationView {

    /**
     * No-op observation.
     */
    Observation NOOP = new NoopObservation();

    /**
     * Create and start an {@link Observation} with the given name. All Observations of
     * the same type must share the same name.
     * 

* When no registry is passed or the observation is * {@link ObservationRegistry.ObservationConfig#observationPredicate(ObservationPredicate) * not applicable}, a no-op observation will be returned. * @param name name of the observation * @param registry observation registry * @return a started observation */ static Observation start(String name, @Nullable ObservationRegistry registry) { return start(name, Context::new, registry); } /** * Creates and starts an {@link Observation}. When the {@link ObservationRegistry} is * null or the no-op registry, this fast returns a no-op {@link Observation} and skips * the creation of the {@link Observation.Context}. This check avoids unnecessary * {@link Observation.Context} creation, which is why it takes a {@link Supplier} for * the context rather than the context directly. If the observation is not enabled * (see * {@link ObservationRegistry.ObservationConfig#observationPredicate(ObservationPredicate) * ObservationConfig#observationPredicate}), a no-op observation will also be * returned. * @param name name of the observation * @param contextSupplier mutable context supplier * @param registry observation registry * @return started observation */ static Observation start(String name, Supplier contextSupplier, @Nullable ObservationRegistry registry) { return createNotStarted(name, contextSupplier, registry).start(); } /** * Creates but does not start an {@link Observation}. Remember to call * {@link Observation#start()} when you want the measurements to start. When no * registry is passed or observation is not applicable will return a no-op * observation. * @param name name of the observation * @param registry observation registry * @return created but not started observation */ static Observation createNotStarted(String name, @Nullable ObservationRegistry registry) { return createNotStarted(name, Context::new, registry); } /** * Creates but does not start an {@link Observation}. Remember to call * {@link Observation#start()} when you want the measurements to start. When the * {@link ObservationRegistry} is null or the no-op registry, this fast returns a * no-op {@link Observation} and skips the creation of the * {@link Observation.Context}. This check avoids unnecessary * {@link Observation.Context} creation, which is why it takes a {@link Supplier} for * the context rather than the context directly. If the observation is not enabled * (see * {@link ObservationRegistry.ObservationConfig#observationPredicate(ObservationPredicate) * ObservationConfig#observationPredicate}), a no-op observation will also be * returned. * @param name name of the observation * @param contextSupplier supplier for mutable context * @param registry observation registry * @return created but not started observation */ static Observation createNotStarted(String name, Supplier contextSupplier, @Nullable ObservationRegistry registry) { if (registry == null || registry.isNoop()) { return NOOP; } Context context = contextSupplier.get(); context.setParentFromCurrentObservation(registry); if (!registry.observationConfig().isObservationEnabled(name, context)) { return NOOP; } return new SimpleObservation(name, registry, context); } // @formatter:off /** * Creates but does not start an {@link Observation}. *

Remember to call {@link Observation#start()} when you want the measurements to start. * When the {@link ObservationRegistry} is null or the no-op registry, this returns a * no-op {@link Observation} and skips the creation of the {@link Observation.Context}. * If the observation is not enabled (see * {@link ObservationRegistry.ObservationConfig#observationPredicate(ObservationPredicate) * ObservationConfig#observationPredicate}), a no-op observation will also be * returned. *

A single {@link ObservationConvention convention} will be used for this observation * for getting its name and {@link KeyValues key values}: *

    *
  1. the {@code customConvention} given as an argument, if not {@code null} *
  2. a {@link GlobalObservationConvention} configured on the * {@link ObservationRegistry.ObservationConfig#observationConvention(GlobalObservationConvention)} * that matches this observation *
  3. as a fallback, the {@code defaultConvention} will be used if none of the above are available *
* @param type of context * @param customConvention custom convention. If {@code null}, the default one will be * picked. * @param defaultConvention default convention when no custom convention was passed, * nor a pre-configured one was found * @param contextSupplier supplier for the observation context * @param registry observation registry * @return created but not started observation */ // @formatter:on static Observation createNotStarted(@Nullable ObservationConvention customConvention, ObservationConvention defaultConvention, Supplier contextSupplier, @Nullable ObservationRegistry registry) { if (registry == null || registry.isNoop()) { return Observation.NOOP; } ObservationConvention convention; T context = contextSupplier.get(); context.setParentFromCurrentObservation(registry); if (customConvention != null) { convention = customConvention; } else { convention = registry.observationConfig().getObservationConvention(context, defaultConvention); } if (!registry.observationConfig().isObservationEnabled(convention.getName(), context)) { return NOOP; } return new SimpleObservation(convention, registry, context); } /** * Creates and starts an {@link Observation}. When no registry is passed or * observation is not applicable will return a no-op observation. *

* Please check the javadoc of * {@link Observation#createNotStarted(ObservationConvention, ObservationConvention, Supplier, ObservationRegistry)} * method for the logic of choosing the convention. *

* @param observationConvention observation convention * @param registry observation registry * @return started observation */ static Observation start(ObservationConvention observationConvention, ObservationRegistry registry) { return start(observationConvention, Context::new, registry); } /** * Creates and starts an {@link Observation}. When the {@link ObservationRegistry} is * null or the no-op registry, this fast returns a no-op {@link Observation} and skips * the creation of the {@link Observation.Context}. This check avoids unnecessary * {@link Observation.Context} creation, which is why it takes a {@link Supplier} for * the context rather than the context directly. If the observation is not enabled * (see * {@link ObservationRegistry.ObservationConfig#observationPredicate(ObservationPredicate) * ObservationConfig#observationPredicate}), a no-op observation will also be * returned. *

* Please check the javadoc of * {@link Observation#createNotStarted(ObservationConvention, ObservationConvention, Supplier, ObservationRegistry)} * method for the logic of choosing the convention. *

* @param type of context * @param observationConvention observation convention * @param contextSupplier mutable context supplier * @param registry observation registry * @return started observation */ static Observation start(ObservationConvention observationConvention, Supplier contextSupplier, ObservationRegistry registry) { return createNotStarted(observationConvention, contextSupplier, registry).start(); } /** * Creates and starts an {@link Observation}. When the {@link ObservationRegistry} is * null or the no-op registry, this fast returns a no-op {@link Observation} and skips * the creation of the {@link Observation.Context}. This check avoids unnecessary * {@link Observation.Context} creation, which is why it takes a {@link Supplier} for * the context rather than the context directly. If the observation is not enabled * (see * {@link ObservationRegistry.ObservationConfig#observationPredicate(ObservationPredicate) * ObservationConfig#observationPredicate}), a no-op observation will also be * returned. Allows to set a custom {@link ObservationConvention} and requires to * provide a default one if neither a custom nor a pre-configured one (via * {@link ObservationRegistry.ObservationConfig#getObservationConvention(Context, ObservationConvention)}) * was found. *

* Please check the javadoc of * {@link Observation#createNotStarted(ObservationConvention, ObservationConvention, Supplier, ObservationRegistry)} * method for the logic of choosing the convention. *

* @param type of context * @param registry observation registry * @param contextSupplier the observation context supplier * @param customConvention custom convention. If {@code null}, the default one will be * picked. * @param defaultConvention default convention when no custom convention was passed, * nor a configured one was found * @return started observation */ static Observation start(@Nullable ObservationConvention customConvention, ObservationConvention defaultConvention, Supplier contextSupplier, ObservationRegistry registry) { return createNotStarted(customConvention, defaultConvention, contextSupplier, registry).start(); } /** * Creates but does not start an {@link Observation}. Remember to call * {@link Observation#start()} when you want the measurements to start. When no * registry is passed or observation is not applicable will return a no-op * observation. *

* Please check the javadoc of * {@link Observation#createNotStarted(ObservationConvention, ObservationConvention, Supplier, ObservationRegistry)} * method for the logic of choosing the convention. *

* @param observationConvention observation convention * @param registry observation registry * @return created but not started observation */ static Observation createNotStarted(ObservationConvention observationConvention, ObservationRegistry registry) { return createNotStarted(observationConvention, Context::new, registry); } /** * Creates but does not start an {@link Observation}. Remember to call * {@link Observation#start()} when you want the measurements to start. When the * {@link ObservationRegistry} is null or the no-op registry, this fast returns a * no-op {@link Observation} and skips the creation of the * {@link Observation.Context}. This check avoids unnecessary * {@link Observation.Context} creation, which is why it takes a {@link Supplier} for * the context rather than the context directly. If the observation is not enabled * (see * {@link ObservationRegistry.ObservationConfig#observationPredicate(ObservationPredicate) * ObservationConfig#observationPredicate}), a no-op observation will also be * returned. *

* Important! If you're using the * {@link ObservationConvention#getContextualName(Context)} method to override the * contextual name you MUST use a non {@code null} context (i.e. the * {@code context} parameter of this method MUST NOT be {@code null}). The * {@link ObservationConvention#getContextualName(Context)} requires a concrete type * of {@link Context} to be passed and if you're not providing one we won't be able to * initialize it ourselves. *

*

* Please check the javadoc of * {@link Observation#createNotStarted(ObservationConvention, ObservationConvention, Supplier, ObservationRegistry)} * method for the logic of choosing the convention. *

* @param type of context * @param observationConvention observation convention * @param contextSupplier mutable context supplier * @param registry observation registry * @return created but not started observation */ static Observation createNotStarted(ObservationConvention observationConvention, Supplier contextSupplier, ObservationRegistry registry) { if (registry == null || registry.isNoop() || observationConvention == NoopObservationConvention.INSTANCE) { return NOOP; } T context = contextSupplier.get(); context.setParentFromCurrentObservation(registry); if (!registry.observationConfig().isObservationEnabled(observationConvention.getName(), context)) { return NOOP; } return new SimpleObservation(observationConvention, registry, context); } /** * Sets the name that can be defined from the contents of the context. E.g. a span * name should not be the default observation name but one coming from an HTTP * request. * @param contextualName contextual name * @return this */ Observation contextualName(@Nullable String contextualName); /** * If you have access to a previously created {@link Observation} you can manually set * the parent {@link Observation} using this method - that way you won't need to open * scopes just to create a child observation. * * If you're using the {@link #openScope()} method then the parent observation will be * automatically set, and you don't have to call this method. * @param parentObservation parent observation to set * @return this */ Observation parentObservation(@Nullable Observation parentObservation); /** * Adds a low cardinality key value. Low cardinality means that this key value will * have a bounded number of possible values. A templated HTTP URL is a good example of * such a key value (e.g. /foo/{userId}). * @param keyValue key value * @return this */ Observation lowCardinalityKeyValue(KeyValue keyValue); /** * Adds a low cardinality key value. Low cardinality means that this key value will * have a bounded number of possible values. A templated HTTP URL is a good example of * such a key value (e.g. /foo/{userId}). * @param key key * @param value value * @return this */ default Observation lowCardinalityKeyValue(String key, String value) { return lowCardinalityKeyValue(KeyValue.of(key, value)); } /** * Adds multiple low cardinality key value instances. Low cardinality means that the * key value will have a bounded number of possible values. A templated HTTP URL is a * good example of such a key value (e.g. /foo/{userId}). * @param keyValues key value instances * @return this */ default Observation lowCardinalityKeyValues(KeyValues keyValues) { for (KeyValue keyValue : keyValues) { lowCardinalityKeyValue(keyValue); } return this; } /** * Adds a high cardinality key value. High cardinality means that this key value will * have an unbounded number of possible values. An HTTP URL is a good example of such * a key value (e.g. /foo/bar, /foo/baz etc.). * @param keyValue key value * @return this */ Observation highCardinalityKeyValue(KeyValue keyValue); /** * Adds a high cardinality key value. High cardinality means that this key value will * have an unbounded number of possible values. An HTTP URL is a good example of such * a key value (e.g. /foo/bar, /foo/baz etc.). * @param key key * @param value value * @return this */ default Observation highCardinalityKeyValue(String key, String value) { return highCardinalityKeyValue(KeyValue.of(key, value)); } /** * Adds multiple high cardinality key value instances. High cardinality means that the * key value will have an unbounded number of possible values. An HTTP URL is a good * example of such a key value (e.g. /foo/bar, /foo/baz etc.). * @param keyValues key value instances * @return this */ default Observation highCardinalityKeyValues(KeyValues keyValues) { for (KeyValue keyValue : keyValues) { highCardinalityKeyValue(keyValue); } return this; } /** * Checks whether this {@link Observation} is no-op. * @return {@code true} when this is a no-op observation */ default boolean isNoop() { return this == NOOP; } /** * Sets an observation convention that can be used to attach key values to the * observation. Implementations should only set the convention when it supports (see: * {@link ObservationConvention#supportsContext(Context)}) the current * {@link Context}. WARNING: You must set the ObservationConvention to the Observation * before it is started. * @param observationConvention observation convention * @return this */ Observation observationConvention(ObservationConvention observationConvention); /** * Signals an error. * @param error error * @return this */ Observation error(Throwable error); /** * Signals an arbitrary {@link Event}. * @param event event * @return this */ Observation event(Event event); /** * Starts the observation. Remember to call this method, otherwise timing calculations * will not take place. * @return this */ Observation start(); /** * Returns the context attached to this observation. * @return corresponding context */ Context getContext(); /** * Returns the context attached to this observation as a read only view. * @return corresponding context */ @Override default ContextView getContextView() { return getContext(); } /** * Stop the observation. Remember to call this method, otherwise timing calculations * won't be finished. */ void stop(); /** * When put in scope, additional operations can take place by the * {@link ObservationHandler}s such as putting entries in thread local. * @return new scope */ Scope openScope(); /** * Observes the passed {@link Runnable}, this means the followings: * *
    *
  • Starts the {@code Observation}
  • *
  • Opens a {@code Scope}
  • *
  • Calls {@link Runnable#run()}
  • *
  • Closes the {@code Scope}
  • *
  • Signals the error to the {@code Observation} if any
  • *
  • Stops the {@code Observation}
  • *
* @param runnable the {@link Runnable} to run */ default void observe(Runnable runnable) { start(); try (Scope scope = openScope()) { runnable.run(); } catch (Throwable error) { error(error); throw error; } finally { stop(); } } default Runnable wrap(Runnable runnable) { return () -> observe(runnable); } /** * Observes the passed {@link CheckedRunnable}, this means the followings: * *
    *
  • Starts the {@code Observation}
  • *
  • Opens a {@code Scope}
  • *
  • Calls {@link CheckedRunnable#run()}
  • *
  • Closes the {@code Scope}
  • *
  • Signals the error to the {@code Observation} if any
  • *
  • Stops the {@code Observation}
  • *
* @param checkedRunnable the {@link CheckedRunnable} to run * @param type of exception thrown */ default void observeChecked(CheckedRunnable checkedRunnable) throws E { start(); try (Scope scope = openScope()) { checkedRunnable.run(); } catch (Throwable error) { error(error); throw error; } finally { stop(); } } default CheckedRunnable wrapChecked(CheckedRunnable checkedRunnable) throws E { return () -> observeChecked(checkedRunnable); } /** * Observes the passed {@link Supplier}, this means the followings: * *
    *
  • Starts the {@code Observation}
  • *
  • Opens a {@code Scope}
  • *
  • Calls {@link Supplier#get()}
  • *
  • Closes the {@code Scope}
  • *
  • Signals the error to the {@code Observation} if any
  • *
  • Stops the {@code Observation}
  • *
* @param supplier the {@link Supplier} to call * @param the type parameter of the {@link Supplier} * @return the result from {@link Supplier#get()} */ @Nullable default T observe(Supplier supplier) { start(); try (Scope scope = openScope()) { return supplier.get(); } catch (Throwable error) { error(error); throw error; } finally { stop(); } } default Supplier wrap(Supplier supplier) { return () -> observe(supplier); } /** * Observes the passed {@link CheckedCallable}, this means the followings: * *
    *
  • Starts the {@code Observation}
  • *
  • Opens a {@code Scope}
  • *
  • Calls {@link CheckedCallable#call()}
  • *
  • Closes the {@code Scope}
  • *
  • Signals the error to the {@code Observation} if any
  • *
  • Stops the {@code Observation}
  • *
* @param checkedCallable the {@link CheckedCallable} to call * @param the return type of the {@link CheckedCallable} * @param type of exception checkedCallable throws * @return the result from {@link CheckedCallable#call()} */ @Nullable default T observeChecked(CheckedCallable checkedCallable) throws E { start(); try (Scope scope = openScope()) { return checkedCallable.call(); } catch (Throwable error) { error(error); throw error; } finally { stop(); } } default CheckedCallable wrapChecked(CheckedCallable checkedCallable) throws E { return () -> observeChecked(checkedCallable); } /** * Observes the passed {@link Function} which provides access to the {@link Context}. * * This means the followings: *
    *
  • Starts the {@code Observation}
  • *
  • Opens a {@code Scope}
  • *
  • Calls {@link Function#apply(Object)} where it gets a {@link Context}
  • *
  • Closes the {@code Scope}
  • *
  • Signals the error to the {@code Observation} if any
  • *
  • Stops the {@code Observation}
  • *
* * NOTE: When the {@link ObservationRegistry} is a noop, this function receives a * default {@link Context} instance which is not the one that has been passed at * {@link Observation} creation. * @param function the {@link Function} to call * @return the result from {@link Function#apply(Object)} * @param the type of input {@link Context} to the function * @param the type parameter of the {@link Function} return * @since 1.11.0 * @deprecated scheduled for removal in 1.15.0, use {@code observe(...)} directly */ @SuppressWarnings({ "unused", "unchecked" }) @Nullable @Deprecated default T observeWithContext(Function function) { InternalLoggerFactory.getInstance(Observation.class) .warn("This method is deprecated. Please migrate to observation.observe(...)"); start(); try (Scope scope = openScope()) { return function.apply((C) getContext()); } catch (Throwable error) { error(error); throw error; } finally { stop(); } } /** * Observes the passed {@link Function} which provides access to the {@link Context}. * * This means the followings: *
    *
  • Starts the {@code Observation}
  • *
  • Opens a {@code Scope}
  • *
  • Calls {@link Function#apply(Object)} where it gets a {@link Context}
  • *
  • Closes the {@code Scope}
  • *
  • Signals the error to the {@code Observation} if any
  • *
  • Stops the {@code Observation}
  • *
* * NOTE: When the {@link ObservationRegistry} is a noop, this function receives a * default {@link Context} instance which is not the one that has been passed at * {@link Observation} creation. * @param function the {@link CheckedFunction} to call * @return the result from {@link Function#apply(Object)} * @param the type of input {@link Context} to the function * @param the type of return to the function * @param type of exception {@link CheckedFunction} throws * @since 1.11.0 * @deprecated scheduled for removal in 1.15.0, use {@code observeChecked(...)} * directly */ @SuppressWarnings({ "unused", "unchecked" }) @Nullable @Deprecated default T observeCheckedWithContext(CheckedFunction function) throws E { InternalLoggerFactory.getInstance(Observation.class) .warn("This method is deprecated. Please migrate to observation.observeChecked(...)"); start(); try (Scope scope = openScope()) { return function.apply((C) getContext()); } catch (Throwable error) { error(error); throw error; } finally { stop(); } } /** * Wraps the given action in a scope and signals an error. * @param runnable the {@link Runnable} to run */ @SuppressWarnings("unused") default void scoped(Runnable runnable) { try (Scope scope = openScope()) { runnable.run(); } catch (Exception exception) { error(exception); throw exception; } } /** * Wraps the given action in a scope and signals an error. * @param checkedRunnable the {@link CheckedRunnable} to run * @param type of exception thrown */ @SuppressWarnings("unused") default void scopedChecked(CheckedRunnable checkedRunnable) throws E { try (Scope scope = openScope()) { checkedRunnable.run(); } catch (Throwable throwable) { error(throwable); throw throwable; } } /** * Wraps the given action in a scope and signals an error. * @param supplier the {@link Supplier} to call * @param the return type of the {@link Supplier} * @return the result from {@link Supplier#get()} */ @SuppressWarnings("unused") default T scoped(Supplier supplier) { try (Scope scope = openScope()) { return supplier.get(); } catch (Exception exception) { error(exception); throw exception; } } /** * Wraps the given action in a scope and signals an error. * @param checkedCallable the {@link CheckedCallable} to call * @param the return type of the {@link CheckedCallable} * @param type of exception checkedCallable throws * @return the result from {@link CheckedCallable#call()} */ @SuppressWarnings("unused") default T scopedChecked(CheckedCallable checkedCallable) throws E { try (Scope scope = openScope()) { return checkedCallable.call(); } catch (Throwable error) { error(error); throw error; } } /** * Tries to run the action against an Observation. If the Observation is null, we just * run the action, otherwise we run the action in scope. * @param parent observation, potentially {@code null} * @param action action to run */ static void tryScoped(@Nullable Observation parent, Runnable action) { if (parent != null) { parent.scoped(action); } else { action.run(); } } /** * Tries to run the action against an Observation. If the Observation is null, we just * run the action, otherwise we run the action in scope. * @param parent observation, potentially {@code null} * @param checkedRunnable the {@link CheckedRunnable} to run * @param type of exception checkedRunnable throws */ static void tryScopedChecked(@Nullable Observation parent, CheckedRunnable checkedRunnable) throws E { if (parent != null) { parent.scopedChecked(checkedRunnable); } else { checkedRunnable.run(); } } /** * Tries to run the action against an Observation. If the Observation is null, we just * run the action, otherwise we run the action in scope. * @param parent observation, potentially {@code null} * @param action action to run * @return result of the action */ static T tryScoped(@Nullable Observation parent, Supplier action) { if (parent != null) { return parent.scoped(action); } return action.get(); } /** * Tries to run the action against an Observation. If the Observation is null, we just * run the action, otherwise we run the action in scope. * @param parent observation, potentially {@code null} * @param checkedCallable the {@link CheckedCallable} to call * @param the return type of the {@link CheckedCallable} * @param type of exception checkedCallable throws * @return the result from {@link CheckedCallable#call()} */ static T tryScopedChecked(@Nullable Observation parent, CheckedCallable checkedCallable) throws E { if (parent != null) { return parent.scopedChecked(checkedCallable); } return checkedCallable.call(); } /** * Scope represent an action within which certain resources (e.g. tracing context) are * put in scope (e.g. in a ThreadLocal). When the scope is closed the resources will * be removed from the scope. * * @since 1.10.0 */ interface Scope extends AutoCloseable { /** * No-op scope. */ Scope NOOP = NoopObservation.NoopScope.INSTANCE; /** * Current observation available within this scope. * @return current observation that this scope was created by */ Observation getCurrentObservation(); /** * Parent scope. * @return previously opened scope when this one was created * @since 1.10.8 */ @Nullable default Observation.Scope getPreviousObservationScope() { return null; } /** * Clears the current scope and notifies the handlers that the scope was closed. * You don't need to call this method manually. If you use try-with-resource, it * will call this for you. Please only call this method if you know what you are * doing and your use-case demands the usage of it. */ @Override void close(); /** * Resets the current scope. The effect of calling this method should be clearing * all related thread local entries. * * You don't need to call this method in most of the cases. Please only call this * method if you know what you are doing and your use-case demands the usage of * it. * @since 1.10.4 */ void reset(); /** * This method assumes that all previous scopes got {@link #reset()}. That means * that in thread locals there are no more entries, and now we can make this scope * current. * * Making this scope current can lead to additional work such as injecting * variables to MDC. * * You don't need to call this method in most of the cases. Please only call this * method if you know what you are doing and your use-case demands the usage of * it. * @since 1.10.6 */ void makeCurrent(); /** * Checks whether this {@link Scope} is no-op. * @return {@code true} when this is a no-op scope */ default boolean isNoop() { return this == NOOP; } } /** * A mutable holder of data required by an {@link ObservationHandler}. When extended * you can provide your own, custom information to be processed by the handlers. * * @since 1.10.0 */ @SuppressWarnings("unchecked") class Context implements ContextView { private final Map map = new ConcurrentHashMap<>(); private String name; @Nullable private String contextualName; @Nullable private Throwable error; @Nullable private ObservationView parentObservation; private final Map lowCardinalityKeyValues = new LinkedHashMap<>(); private final Map highCardinalityKeyValues = new LinkedHashMap<>(); /** * The observation name. * @return name */ @Override public String getName() { return this.name; } /** * Sets the observation name. * @param name observation name */ public void setName(String name) { this.name = name; } /** * Returns the contextual name. The name that makes sense within the current * context (e.g. name derived from HTTP request). * @return contextual name */ @Override public String getContextualName() { return this.contextualName; } /** * Sets the contextual name. * @param contextualName name */ public void setContextualName(@Nullable String contextualName) { this.contextualName = contextualName; } /** * Returns the parent {@link ObservationView}. * @return parent observation or {@code null} if there was no parent */ @Nullable public ObservationView getParentObservation() { return parentObservation; } /** * Sets the parent {@link ObservationView}. * @param parentObservation parent observation to set */ public void setParentObservation(@Nullable ObservationView parentObservation) { this.parentObservation = parentObservation; } /** * Sets the parent {@link ObservationView} to current one if parent is null and * current one exists. * @param registry the {@link ObservationRegistry} in using */ void setParentFromCurrentObservation(ObservationRegistry registry) { if (this.parentObservation == null) { Observation currentObservation = registry.getCurrentObservation(); if (currentObservation != null) { setParentObservation(currentObservation); } } } /** * Error that occurred while processing the {@link Observation}. * @return error (null if there wasn't any) */ @Nullable @Override public Throwable getError() { return this.error; } /** * Sets an error that occurred while processing the {@link Observation}. * @param error error */ public void setError(Throwable error) { this.error = error; } /** * Puts an element to the context. * @param key key * @param object value * @param value type * @return this for chaining */ public Context put(Object key, T object) { this.map.put(key, object); return this; } /** * Gets an entry from the context. Returns {@code null} when entry is not present. * @param key key * @param value type * @return entry or {@code null} if not present */ @Override @Nullable public T get(Object key) { return (T) this.map.get(key); } /** * Removes an entry from the context. * @param key key by which to remove an entry * @return the previous value associated with the key, or null if there was no * mapping for the key */ public Object remove(Object key) { return this.map.remove(key); } /** * Gets an entry from the context. Throws exception when entry is not present. * @param key key * @param value type * @throws IllegalArgumentException if not present * @return entry */ @Override @NonNull public T getRequired(Object key) { T object = (T) this.map.get(key); if (object == null) { throw new IllegalArgumentException("Context does not have an entry for key [" + key + "]"); } return object; } /** * Checks if context contains a key. * @param key key * @return {@code true} when the context contains the entry with the given key */ @Override public boolean containsKey(Object key) { return this.map.containsKey(key); } /** * Returns an element or default if not present. * @param key key * @param defaultObject default object to return * @param value type * @return object or default if not present */ @Override public T getOrDefault(Object key, T defaultObject) { return (T) this.map.getOrDefault(key, defaultObject); } /** * Returns an element or calls a mapping function if entry not present. The * function will insert the value to the map. * @param key key * @param mappingFunction mapping function * @param value type * @return object or one derived from the mapping function if not present */ public T computeIfAbsent(Object key, Function mappingFunction) { return (T) this.map.computeIfAbsent(key, mappingFunction); } /** * Clears the entries from the context. */ public void clear() { this.map.clear(); } /** * Adds a low cardinality key value - those will be appended to those fetched from * the {@link ObservationConvention#getLowCardinalityKeyValues(Context)} method. * @param keyValue a key value * @return this context */ public Context addLowCardinalityKeyValue(KeyValue keyValue) { this.lowCardinalityKeyValues.put(keyValue.getKey(), keyValue); return this; } /** * Adds a high cardinality key value - those will be appended to those fetched * from the {@link ObservationConvention#getHighCardinalityKeyValues(Context)} * method. * @param keyValue a key value * @return this context */ public Context addHighCardinalityKeyValue(KeyValue keyValue) { this.highCardinalityKeyValues.put(keyValue.getKey(), keyValue); return this; } /** * Removes a low cardinality key value by looking at its key - those will be * removed to those fetched from the * {@link ObservationConvention#getLowCardinalityKeyValues(Context)} method. * @param keyName name of the key * @return this context * @since 1.10.1 */ public Context removeLowCardinalityKeyValue(String keyName) { this.lowCardinalityKeyValues.remove(keyName); return this; } /** * Removes a high cardinality key value by looking at its key - those will be * removed to those fetched from the * {@link ObservationConvention#getHighCardinalityKeyValues(Context)} method. * @param keyName name of the key * @return this context * @since 1.10.1 */ public Context removeHighCardinalityKeyValue(String keyName) { this.highCardinalityKeyValues.remove(keyName); return this; } /** * Adds multiple low cardinality key values at once. * @param keyValues collection of key values * @return this context */ public Context addLowCardinalityKeyValues(KeyValues keyValues) { for (KeyValue keyValue : keyValues) { addLowCardinalityKeyValue(keyValue); } return this; } /** * Adds multiple high cardinality key values at once. * @param keyValues collection of key values * @return this context */ public Context addHighCardinalityKeyValues(KeyValues keyValues) { for (KeyValue keyValue : keyValues) { addHighCardinalityKeyValue(keyValue); } return this; } /** * Removes multiple low cardinality key values at once. * @param keyNames collection of key names * @return this context * @since 1.10.1 */ public Context removeLowCardinalityKeyValues(String... keyNames) { for (String keyName : keyNames) { removeLowCardinalityKeyValue(keyName); } return this; } /** * Removes multiple high cardinality key values at once. * @param keyNames collection of key names * @return this context * @since 1.10.1 */ public Context removeHighCardinalityKeyValues(String... keyNames) { for (String keyName : keyNames) { removeHighCardinalityKeyValue(keyName); } return this; } @NonNull @Override public KeyValues getLowCardinalityKeyValues() { return KeyValues.of(this.lowCardinalityKeyValues.values()); } @NonNull @Override public KeyValues getHighCardinalityKeyValues() { return KeyValues.of(this.highCardinalityKeyValues.values()); } @Override public KeyValue getLowCardinalityKeyValue(String key) { return this.lowCardinalityKeyValues.get(key); } @Override public KeyValue getHighCardinalityKeyValue(String key) { return this.highCardinalityKeyValues.get(key); } @NonNull @Override public KeyValues getAllKeyValues() { return getLowCardinalityKeyValues().and(getHighCardinalityKeyValues()); } @Override public String toString() { return "name='" + name + '\'' + ", contextualName='" + contextualName + '\'' + ", error='" + error + '\'' + ", lowCardinalityKeyValues=" + toString(getLowCardinalityKeyValues()) + ", highCardinalityKeyValues=" + toString(getHighCardinalityKeyValues()) + ", map=" + toString(map) + ", parentObservation=" + parentObservation; } private String toString(KeyValues keyValues) { return keyValues.stream() .map(keyValue -> String.format("%s='%s'", keyValue.getKey(), keyValue.getValue())) .collect(Collectors.joining(", ", "[", "]")); } private String toString(Map map) { return map.entrySet() .stream() .map(entry -> String.format("%s='%s'", entry.getKey(), entry.getValue())) .collect(Collectors.joining(", ", "[", "]")); } } /** * An arbitrary event that you can extend and signal during an {@link Observation}. * This helps you to tell to the {@link ObservationHandler} that something happened. * If you want to signal an exception/error, please use * {@link Observation#error(Throwable)} instead. */ interface Event { /** * Creates an {@link Event} for the given names. * @param name The name of the event (should have low cardinality). * @param contextualName The contextual name of the event (can have high * cardinality). * @return event */ static Event of(String name, String contextualName) { return new SimpleEvent(name, contextualName); } /** * Creates an {@link Event} for the given names and timestamp (wall time). * @param name The name of the event (should have low cardinality). * @param contextualName The contextual name of the event (can have high * cardinality). * @param wallTime Wall time in milliseconds since the epoch * @return event * @since 1.12.0 */ static Event of(String name, String contextualName, long wallTime) { return new SimpleEvent(name, contextualName, wallTime); } /** * Creates an {@link Event} for the given name. * @param name The name of the event (should have low cardinality). * @return event */ static Event of(String name) { return of(name, name); } /** * Returns the name of the event. * @return the name of the event. */ String getName(); /** * Wall time in milliseconds since the epoch. Typically equivalent to * {@link System#currentTimeMillis()}. Should not be used to determine durations. * Used for timestamping events that happened during Observations. * @return Wall time in milliseconds since the epoch * @since 1.12.0 */ default long getWallTime() { return 0; } /** * Returns the contextual name of the event. You can use {@code %s} to represent * dynamic entries that should be resolved at runtime via * {@link String#format(String, Object...)}. * @return the contextual name of the event. */ default String getContextualName() { return getName(); } /** * Creates a new event with the given dynamic entries for the contextual name. * @param dynamicEntriesForContextualName variables to be resolved in * {@link Event#getContextualName()} via {@link String#format(String, Object...)}. * @return event */ default Event format(Object... dynamicEntriesForContextualName) { return Event.of(getName(), String.format(getContextualName(), dynamicEntriesForContextualName)); } } /** * Read only view on the {@link Context}. */ interface ContextView { /** * The observation name. * @return name */ String getName(); /** * Returns the contextual name. The name that makes sense within the current * context (e.g. name derived from HTTP request). * @return contextual name */ @Nullable String getContextualName(); /** * Returns the parent {@link ObservationView}. * @return parent observation or {@code null} if there was no parent */ @Nullable ObservationView getParentObservation(); /** * Error that occurred while processing the {@link Observation}. * @return error (null if there wasn't any) */ @Nullable Throwable getError(); /** * Gets an entry from the context. Returns {@code null} when entry is not present. * @param key key * @param value type * @return entry or {@code null} if not present */ @Nullable T get(Object key); /** * Gets an entry from the context. Throws exception when entry is not present. * @param key key * @param value type * @throws IllegalArgumentException if not present * @return entry */ @NonNull T getRequired(Object key); /** * Checks if context contains a key. * @param key key * @return {@code true} when the context contains the entry with the given key */ boolean containsKey(Object key); /** * Returns an element or default if not present. * @param key key * @param defaultObject default object to return * @param value type * @return object or default if not present */ T getOrDefault(Object key, T defaultObject); /** * Returns an element or default if not present. * @param key key * @param defaultObjectSupplier supplier for default object to return * @param value type * @return object or default if not present * @since 1.11.0 */ default T getOrDefault(Object key, Supplier defaultObjectSupplier) { T value = get(key); return value != null ? value : defaultObjectSupplier.get(); } /** * Returns low cardinality key values. * @return low cardinality key values */ KeyValues getLowCardinalityKeyValues(); /** * Returns high cardinality key values. * @return high cardinality key values */ @NonNull KeyValues getHighCardinalityKeyValues(); /** * Returns a low cardinality key value or {@code null} if not present. * @param key key * @return a low cardinality key value or {@code null} */ @Nullable KeyValue getLowCardinalityKeyValue(String key); /** * Returns a high cardinality key value or {@code null} if not present. * @param key key * @return a high cardinality key value or {@code null} */ @Nullable KeyValue getHighCardinalityKeyValue(String key); /** * Returns all key values. * @return all key values */ @NonNull KeyValues getAllKeyValues(); } /** * A functional interface like {@link Runnable} but it can throw a {@link Throwable}. */ @FunctionalInterface interface CheckedRunnable { void run() throws E; } /** * A functional interface like {@link Callable} but it can throw a {@link Throwable}. */ @FunctionalInterface interface CheckedCallable { T call() throws E; } /** * A functional interface like {@link Function} but it can throw a {@link Throwable}. * * @since 1.11.0 */ @FunctionalInterface interface CheckedFunction { @Nullable R apply(T t) throws E; } }




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