Fix to prevent override a implicit AsyncTaskExecutor (#313) - #314

🏁 Script executed:

#!/bin/bash
set -eu

file='instrument-starters/opentracing-spring-cloud-core/src/main/java/io/opentracing/contrib/spring/cloud/async/DefaultAsyncAutoConfiguration.java'

printf '%s\n' '--- target file ---'
cat -n "$file"

printf '%s\n' '--- relevant project files ---'
git ls-files | grep -E '(^|/)(pom\.xml|build\.gradle(\.kts)?|.*Async.*Test.*|.*async.*)' | head -200

printf '%s\n' '--- async-related references ---'
rg -n --glob '*.java' --glob '*.xml' --glob 'pom.xml' \
  'DefaultTracedAsyncConfigurerSupport|DefaultAsyncAutoConfiguration|ConditionalOnMissingBean|AsyncConfigurer|TaskExecutor|`@Async`|taskExecutor' \
  instrument-starters opentracing-spring-cloud-* 2>/dev/null | head -300

Repository: opentracing-contrib/java-spring-cloud

Length of output: 24865

🏁 Script executed:

#!/bin/bash
set -eu

printf '%s\n' '--- root dependency versions ---'
cat -n pom.xml | sed -n '1,240p'

printf '%s\n' '--- core module dependencies and test setup ---'
cat -n instrument-starters/opentracing-spring-cloud-core/pom.xml | sed -n '1,260p'

printf '%s\n' '--- existing implicit async test ---'
cat -n instrument-starters/opentracing-spring-cloud-core/src/test/java/io/opentracing/contrib/spring/cloud/async/AsyncImplicitOneTest.java

printf '%s\n' '--- default async-related production classes ---'
cat -n instrument-starters/opentracing-spring-cloud-core/src/main/java/io/opentracing/contrib/spring/cloud/async/CustomAsyncConfigurerAutoConfiguration.java
cat -n instrument-starters/opentracing-spring-cloud-core/src/main/java/io/opentracing/contrib/spring/cloud/async/ExecutorBeanPostProcessor.java | sed -n '1,180p'

printf '%s\n' '--- all test fixtures that declare Executor beans ---'
rg -n -C 5 --glob '*.java' \
  'public (Executor|TaskExecutor)|`@Bean`|threadPoolTaskExecutor|simpleAsyncTaskExecutor|taskExecutor' \
  instrument-starters/opentracing-spring-cloud-core/src/test/java/io/opentracing/contrib/spring/cloud/async

Repository: opentracing-contrib/java-spring-cloud

Length of output: 48095

🌐 Web query:

Spring Framework EnableAsync default executor selection unique TaskExecutor bean Executor named taskExecutor source

💡 Result:

When using @EnableAsync, the Spring Framework resolves the TaskExecutor to be used for asynchronous method execution through a specific search order [1][2]. The selection logic, implemented in AsyncExecutionAspectSupport, follows this sequence [3]: 1. Unique TaskExecutor Bean: Spring first searches for a unique bean of type TaskExecutor in the application context [3][1]. 2. Bean Named "taskExecutor": If a unique TaskExecutor bean is not found, it then looks for an Executor bean specifically named "taskExecutor" [3][1]. 3. Local Default: If neither of the above is resolvable, Spring falls back to using a SimpleAsyncTaskExecutor as the default [1][2]. It is important to note that if multiple beans of type TaskExecutor are present and none are named "taskExecutor", or if there is no @Primary bean configured, this will trigger a NoUniqueBeanDefinitionException or result in the lookup failing back to the "taskExecutor" search (which may also fail) [3]. In the context of Spring Boot, these behaviors are often influenced by auto-configuration [4][5]. Spring Boot may register its own beans (such as applicationTaskExecutor) which can override or interact with this default lookup mechanism [4][5]. To explicitly control which executor is used, you can implement the AsyncConfigurer interface or mark a specific bean as @Primary [4][5].

Citations:

• 1: https://docs.spring.io/spring-framework/docs/current/javadoc-api/org/springframework/scheduling/annotation/EnableAsync.html?is-external=true
• 2: https://github.com/spring-projects/spring-framework/blob/master/spring-context/src/main/java/org/springframework/scheduling/annotation/EnableAsync.java
• 3: https://github.com/spring-projects/spring-framework/blob/master/spring-aop/src/main/java/org/springframework/aop/interceptor/AsyncExecutionAspectSupport.java
• 4: https://docs.spring.io/spring-boot/reference/features/task-execution-and-scheduling.html
• 5: https://docs.spring.io/spring-boot/3.5.11/reference/features/task-execution-and-scheduling.html

🌐 Web query:

Spring Boot ConditionalOnMissingBean multiple types semantics all requirements must be met

💡 Result:

The semantics of @ConditionalOnMissingBean regarding multiple types are based on a "logical AND" requirement for the absence of beans [1][2]. When you specify multiple types, the condition only matches if none of the specified requirements are met in the BeanFactory [1][2]. In other words, for the condition to be true, every single specified type must be missing from the context [3]. Key semantic details include: 1. Requirements are independent: The requirements do not need to be met by the same bean; the condition simply verifies that no bean matching any of the specified types exists [1][2]. 2. Collective Absence: If even one bean exists in the BeanFactory that matches any of the specified types, the @ConditionalOnMissingBean condition will fail (i.e., it will not match, and the associated bean will not be created) [3]. 3. Multiple Attributes: When multiple attributes are used within the same annotation (such as type, name, and annotation), they are also evaluated together. The bean will only be created if the conditions for all specified requirements are met—meaning the "missing" criteria for each attribute must be satisfied [1][2]. 4. Generics Note: For recent versions of Spring Boot (3.5+), note that generic type parameters are considered by default [4]. If you need to match without regard to generic type parameters, you may need to use raw types or specific workarounds like the wildcard (?) type [4]. In summary, @ConditionalOnMissingBean acts as a collective guard: it requires the total absence of all listed beans or types to trigger the creation of the bean it protects [1][3]. If any conflicting bean is found, the condition is not met [3].

Citations:

• 1: https://docs.spring.io/spring-boot/api/java/org/springframework/boot/autoconfigure/condition/ConditionalOnMissingBean.html
• 2: https://docs.spring.io/spring-boot/3.5/api/java/org/springframework/boot/autoconfigure/condition/ConditionalOnMissingBean.html
• 3: Documentation clarification on ConditionalOnMissingBean spring-projects/spring-boot#16906
• 4: Update the 3.5 release notes with more information about generics and bean-based conditions spring-projects/spring-boot#47021

🏁 Script executed:

#!/bin/bash
set -eu

python3 - <<'PY'
import re
import urllib.request

urls = {
    "spring-async-support": "https://raw.githubusercontent.com/spring-projects/spring-framework/v5.2.0.RELEASE/spring-context/src/main/java/org/springframework/scheduling/annotation/AbstractAsyncConfiguration.java",
    "spring-async-selection": "https://raw.githubusercontent.com/spring-projects/spring-framework/v5.2.0.RELEASE/spring-aop/src/main/java/org/springframework/aop/interceptor/AsyncExecutionAspectSupport.java",
    "boot-missing-condition": "https://raw.githubusercontent.com/spring-projects/spring-boot/v2.2.0.RELEASE/spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/condition/OnBeanCondition.java",
}

for name, url in urls.items():
    print(f"--- {name} ---")
    try:
        text = urllib.request.urlopen(url, timeout=15).read().decode()
    except Exception as exc:
        print(f"FETCH_ERROR: {exc}")
        continue

    if name == "spring-async-support":
        patterns = [r"setConfigurers\\([\\s\\S]{0,1800}"]
    elif name == "spring-async-selection":
        patterns = [r"getDefaultExecutor\\([\\s\\S]{0,1800}"]
    else:
        patterns = [r"getMatchingBeans\\([\\s\\S]{0,1800}", r"ConditionalOnMissingBean"]

    for pattern in patterns:
        match = re.search(pattern, text)
        print(match.group(0) if match else "PATTERN_NOT_FOUND")
PY

Repository: opentracing-contrib/java-spring-cloud

Length of output: 710

🌐 Web query:

site:github.com/spring-projects/spring-framework v5.2.0.RELEASE AsyncExecutionAspectSupport getDefaultExecutor

💡 Result:

In the Spring Framework, including version 5.2.0.RELEASE, the getDefaultExecutor method is a protected method defined in the AsyncExecutionAspectSupport class [1][2]. It is responsible for resolving the default Executor to be used for asynchronous task execution [1][3]. The resolution logic implemented in AsyncExecutionAspectSupport.getDefaultExecutor follows these steps [1][2]: 1. It attempts to find a unique bean of type TaskExecutor in the provided BeanFactory [1][2]. 2. If no unique TaskExecutor bean is found, it attempts to find an Executor bean explicitly named "taskExecutor" [1][2]. 3. If neither of these can be resolved, the method returns null [1][2]. In practice, this method is typically overridden by subclasses such as AsyncExecutionInterceptor [3][4]. The override in AsyncExecutionInterceptor invokes the superclass implementation and, if the result is null, falls back to creating a new SimpleAsyncTaskExecutor instance to ensure an executor is available for local use [3][5][4].

Citations:

• 1: https://github.com/spring-projects/spring-framework/blob/main/spring-aop/src/main/java/org/springframework/aop/interceptor/AsyncExecutionAspectSupport.java
• 2: https://github.com/spring-projects/spring-framework/blob/master/spring-aop/src/main/java/org/springframework/aop/interceptor/AsyncExecutionAspectSupport.java
• 3: https://github.com/spring-projects/spring-framework/blob/master/spring-aop/src/main/java/org/springframework/aop/interceptor/AsyncExecutionInterceptor.java
• 4: https://github.com/spring-projects/spring-framework/blob/v6.0.11/spring-aop/src/main/java/org/springframework/aop/interceptor/AsyncExecutionInterceptor.java
• 5: https://github.com/spring-projects/spring-framework/blob/5e808ad0183a63944ab08017a13cbc7ed75bc581/spring-aop/src/main/java/org/springframework/aop/interceptor/AsyncExecutionInterceptor.java

🌐 Web query:

site:github.com/spring-projects/spring-boot v2.2.0.RELEASE OnBeanCondition ConditionalOnMissingBean

💡 Result:

In Spring Boot 2.2.0.RELEASE, @ConditionalOnMissingBean is a conditional annotation that ensures a bean is only created if no existing beans meeting the specified requirements are already present in the BeanFactory [1]. It is implemented using the OnBeanCondition class [1]. Key behavioral characteristics and usage recommendations include: 1. Recommended Use: It is strongly recommended to use this condition only on auto-configuration classes [2][3][4]. Because the condition evaluates against bean definitions processed by the application context at that specific moment, usage on standard user-defined configuration classes can lead to unpredictable behavior depending on the order of bean definition loading [2][4]. 2. Mechanism: - The condition checks for the presence of beans based on class types, annotation types, or specific bean names [1]. - It only considers beans that are autowire candidates or default candidates; other beans are ignored [1]. - When multiple attributes are provided, the condition behaves as a logical OR in terms of its target evaluation, but the cumulative effect is that it verifies the absence of the specified criteria [5][6]. 3. Limitations and Nuances: - Timing: The condition can only evaluate bean definitions that have been processed by the context so far [2][3]. If a bean is created by another auto-configuration, the configuration using @ConditionalOnMissingBean must be configured to run after that auto-configuration [2][3]. - Implicit Type Defaults: When used on a @Bean method, the annotation may implicitly use the method's return type as a constraint if not explicitly specified, which can sometimes lead to unexpected matching behavior [5][7]. - Type Information: The condition relies on available type information within the BeanFactory [8]. It avoids triggering early bean initialization where possible, preferring to inspect bean definitions (e.g., factory method return types) before full bean instantiation [8]. Providing explicit type information in bean definitions is recommended for consistent results [8][9].

Citations:

• 1: https://github.com/spring-projects/spring-boot/blob/main/spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/condition/ConditionalOnMissingBean.java
• 2: @ConditionalOnMissingBean with conditional missing bean results in missing bean spring-projects/spring-boot#24227
• 3: ConditionalOnMissingBean on JpaRepository beans  spring-projects/spring-boot#21633
• 4: ConditionalOnBean behaves weirdly when combined with ConditionalOnMissingBean spring-projects/spring-boot#20855
• 5: ConditionalOnMissingBean does not handle annotation correctly spring-projects/spring-boot#16907
• 6: Documentation clarification on ConditionalOnMissingBean spring-projects/spring-boot#16906
• 7: Improve documentation of how @ConditionalOnBean evaluates all of its attributes spring-projects/spring-boot#15177
• 8: Recommend that bean definitions provide as much type information as possible spring-projects/spring-boot#22925
• 9: @ConditionalOnBean with an annotation attribute may instantiate factory bean that provides no type information spring-projects/spring-boot#8269

🏁 Script executed:

#!/bin/bash
set -eu

for spec in \
  'spring-async-support|https://raw.githubusercontent.com/spring-projects/spring-framework/v5.2.0.RELEASE/spring-context/src/main/java/org/springframework/scheduling/annotation/AbstractAsyncConfiguration.java' \
  'spring-async-selection|https://raw.githubusercontent.com/spring-projects/spring-framework/v5.2.0.RELEASE/spring-aop/src/main/java/org/springframework/aop/interceptor/AsyncExecutionAspectSupport.java' \
  'boot-condition|https://raw.githubusercontent.com/spring-projects/spring-boot/v2.2.0.RELEASE/spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/condition/OnBeanCondition.java'
do
  name=${spec%%|*}
  url=${spec#*|}
  printf '%s\n' "--- $name ---"
  curl -fsSLk "$url" | grep -n -A35 -B8 -E \
    'setConfigurers|getDefaultExecutor|ConditionalOnMissingBean|getMatchingBeans' | head -180 || true
done

Repository: opentracing-contrib/java-spring-cloud

Length of output: 13933

🏁 Script executed:

#!/bin/bash
set -eu

for spec in \
  'async-interceptor|https://raw.githubusercontent.com/spring-projects/spring-framework/v5.2.0.RELEASE/spring-aop/src/main/java/org/springframework/aop/interceptor/AsyncExecutionInterceptor.java' \
  'async-post-processor|https://raw.githubusercontent.com/spring-projects/spring-framework/v5.2.0.RELEASE/spring-context/src/main/java/org/springframework/scheduling/annotation/AsyncAnnotationBeanPostProcessor.java' \
  'proxy-async-config|https://raw.githubusercontent.com/spring-projects/spring-framework/v5.2.0.RELEASE/spring-context/src/main/java/org/springframework/scheduling/annotation/ProxyAsyncConfiguration.java'
do
  name=${spec%%|*}
  url=${spec#*|}
  printf '%s\n' "--- $name ---"
  curl -fsSLk "$url" | grep -n -A32 -B10 -E \
    'SimpleAsyncTaskExecutor|determineAsyncExecutor|configure|setExecutor|executor' | head -220 || true
done

Repository: opentracing-contrib/java-spring-cloud

Length of output: 11729