java.lang.Object
- com.linecorp.armeria.common.Flags

```
public final class Flags
extends Object
```
The system properties that affect Armeria's runtime behavior.

Method Summary

Modifier and Type	Method	Description
`static ExceptionVerbosity`	`annotatedServiceExceptionVerbosity()`	Returns the verbosity of exceptions logged by annotated HTTP services.
`static List<String>`	`cachedHeaders()`	Returns the value of the `cachedHeaders` parameter which contains a comma-separated list of headers whose values are cached using `headerValueCache`.
`static Optional<String>`	`compositeServiceCacheSpec()`	Returns the value of the `compositeServiceCache` parameter.
`static String`	`defaultBackoffSpec()`	Returns the default value of the `backoffSpec` parameter when instantiating a `Backoff` using `Backoff.of(String)`.
`static long`	`defaultClientIdleTimeoutMillis()`	Returns the default client-side idle timeout of a connection for keep-alive in milliseconds.
`static long`	`defaultConnectTimeoutMillis()`	Returns the default client-side timeout of a socket connection attempt in milliseconds.
`static int`	`defaultHttp1MaxChunkSize()`	Returns the default maximum length of each chunk in an HTTP/1 response content.
`static int`	`defaultHttp1MaxHeaderSize()`	Returns the default maximum length of all headers in an HTTP/1 response.
`static int`	`defaultHttp1MaxInitialLineLength()`	Returns the default maximum length of an HTTP/1 response initial line.
`static int`	`defaultHttp2InitialConnectionWindowSize()`	Returns the default value of the `ServerBuilder.http2InitialConnectionWindowSize(int)` and `ClientFactoryBuilder.http2InitialConnectionWindowSize(int)` option.
`static int`	`defaultHttp2InitialStreamWindowSize()`	Returns the default value of the `ServerBuilder.http2InitialStreamWindowSize(int)` and `ClientFactoryBuilder.http2InitialStreamWindowSize(int)` option.
`static int`	`defaultHttp2MaxFrameSize()`	Returns the default value of the `ServerBuilder.http2MaxFrameSize(int)` and `ClientFactoryBuilder.http2MaxFrameSize(int)` option.
`static long`	`defaultHttp2MaxHeaderListSize()`	Returns the default value of the `ServerBuilder.http2MaxHeaderListSize(long)` and `ClientFactoryBuilder.http2MaxHeaderListSize(long)` option.
`static long`	`defaultHttp2MaxStreamsPerConnection()`	Returns the default value of the `ServerBuilder.http2MaxStreamsPerConnection(long)` option.
`static long`	`defaultMaxRequestLength()`	Returns the default server-side maximum length of a request.
`static long`	`defaultMaxResponseLength()`	Returns the default client-side maximum length of a response.
`static int`	`defaultMaxTotalAttempts()`	Returns the default maximum number of total attempts.
`static long`	`defaultRequestTimeoutMillis()`	Returns the default server-side timeout of a request in milliseconds.
`static long`	`defaultResponseTimeoutMillis()`	Returns the default client-side timeout of a response in milliseconds.
`static long`	`defaultServerIdleTimeoutMillis()`	Returns the default server-side idle timeout of a connection for keep-alive in milliseconds.
`static boolean`	`defaultUseHttp1Pipelining()`	Returns the default value of the `ClientFactoryBuilder.useHttp1Pipelining(boolean)` option.
`static boolean`	`defaultUseHttp2Preface()`	Returns the default value of the `ClientFactoryBuilder.useHttp2Preface(boolean)` option.
`static long`	`defaultWriteTimeoutMillis()`	Returns the default client-side timeout of a socket write attempt in milliseconds.
`static boolean`	`dumpOpenSslInfo()`	Returns whether information about the OpenSSL environment should be dumped when first starting the application, including supported ciphers.
`static Optional<String>`	`fileServiceCacheSpec()`	Returns the value of the `fileServiceCache` parameter.
`static Optional<String>`	`headerValueCacheSpec()`	Returns the value of the `headerValueCache` parameter.
`static int`	`maxNumConnections()`	Returns the default server-side maximum number of connections.
`static int`	`numCommonBlockingTaskThreads()`	Returns the default number of blocking task executor threads.
`static int`	`numCommonWorkers()`	Returns the default number of common worker group threads.
`static Optional<String>`	`parsedPathCacheSpec()`	Returns the value of the `parsedPathCache` parameter.
`static Optional<String>`	`routeCacheSpec()`	Returns the value of the `routeCache` parameter.
`static Optional<String>`	`routeDecoratorCacheSpec()`	Returns the value of the `routeDecoratorCache` parameter.
`static boolean`	`useEpoll()`	Returns whether the JNI-based `/dev/epoll` socket I/O is enabled.
`static boolean`	`useJdkDnsResolver()`	Enables `DefaultAddressResolverGroup` that resolves domain name using JDK's built-in domain name lookup mechanism.
`static boolean`	`useOpenSsl()`	Returns whether the JNI-based TLS support with OpenSSL is enabled.
`static Sampler<Class<? extends Throwable>>`	`verboseExceptionSampler()`	Returns the `Sampler` that determines whether to retain the stack trace of the exceptions that are thrown frequently by Armeria.
`static String`	`verboseExceptionSamplerSpec()`	Returns the specification string of the `Sampler` that determines whether to retain the stack trace of the exceptions that are thrown frequently by Armeria.
`static boolean`	`verboseResponses()`	Returns whether the verbose response mode is enabled.
`static boolean`	`verboseSocketExceptions()`	Returns whether to log the socket exceptions which are mostly harmless.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Method Detail
  - verboseExceptionSampler
```
public static Sampler<Class<? extends Throwable>> verboseExceptionSampler()
```
    Returns the Sampler that determines whether to retain the stack trace of the exceptions that are thrown frequently by Armeria.
    
    See Also:
    
    verboseExceptionSamplerSpec()
  - verboseExceptionSamplerSpec
```
public static String verboseExceptionSamplerSpec()
```
    Returns the specification string of the Sampler that determines whether to retain the stack trace of the exceptions that are thrown frequently by Armeria. A sampled exception will have the stack trace while the others will have an empty stack trace to eliminate the cost of capturing the stack trace.
    The default value of this flag is "rate-limit=10", which retains the stack trace of the exceptions at the maximum rate of 10 exceptions/sec. Specify the -Dcom.linecorp.armeria.verboseExceptions=<specification> JVM option to override the default. See Sampler.of(String) for the specification string format.
  - verboseSocketExceptions
```
public static boolean verboseSocketExceptions()
```
    Returns whether to log the socket exceptions which are mostly harmless. If enabled, the following exceptions will be logged:
    
    ClosedChannelException
    
    ClosedSessionException
    
    IOException - 'Connection reset/closed/aborted by peer'
    
    'Broken pipe'
    
    Http2Exception - 'Stream closed'
    
    SSLException - 'SSLEngine closed already'
    
    It is recommended to keep this flag disabled, because it increases the amount of log messages for the errors you usually do not have control over, e.g. unexpected socket disconnection due to network or remote peer issues.
    
    This flag is disabled by default. Specify the -Dcom.linecorp.armeria.verboseSocketExceptions=true JVM option to enable it.
    See Also:
    
    Exceptions.isExpected(Throwable)
  - verboseResponses
```
public static boolean verboseResponses()
```
    Returns whether the verbose response mode is enabled. When enabled, the server responses will contain the exception type and its full stack trace, which may be useful for debugging while potentially insecure. When disabled, the server responses will not expose such server-side details to the client.
    This flag is disabled by default. Specify the -Dcom.linecorp.armeria.verboseResponses=true JVM option or use ServerBuilder.verboseResponses(boolean) to enable it.
  - useEpoll
```
public static boolean useEpoll()
```
    Returns whether the JNI-based /dev/epoll socket I/O is enabled. When enabled on Linux, Armeria uses /dev/epoll directly for socket I/O. When disabled, java.nio socket API is used instead.
    This flag is enabled by default for supported platforms. Specify the -Dcom.linecorp.armeria.useEpoll=false JVM option to disable it.
  - useOpenSsl
```
public static boolean useOpenSsl()
```
    Returns whether the JNI-based TLS support with OpenSSL is enabled. When enabled, Armeria uses OpenSSL for processing TLS connections. When disabled, the current JVM's default SSLEngine is used instead.
    This flag is enabled by default for supported platforms. Specify the -Dcom.linecorp.armeria.useOpenSsl=false JVM option to disable it.
  - dumpOpenSslInfo
```
public static boolean dumpOpenSslInfo()
```
    Returns whether information about the OpenSSL environment should be dumped when first starting the application, including supported ciphers.
    This flag is disabled by default. Specify the -Dcom.linecorp.armeria.dumpOpenSslInfo=true JVM option to enable it.
  - maxNumConnections
```
public static int maxNumConnections()
```
    Returns the default server-side maximum number of connections.
    The default value of this flag is 2147483647. Specify the -Dcom.linecorp.armeria.maxNumConnections=<integer> JVM option to override the default value.
  - numCommonWorkers
```
public static int numCommonWorkers()
```
    Returns the default number of common worker group threads. Note that this value has effect only if a user did not specify a worker group.
    The default value of this flag is 2 * <numCpuCores>. Specify the -Dcom.linecorp.armeria.numCommonWorkers=<integer> JVM option to override the default value.
  - numCommonBlockingTaskThreads
```
public static int numCommonBlockingTaskThreads()
```
    Returns the default number of blocking task executor threads. Note that this value has effect only if a user did not specify a blocking task executor.
    The default value of this flag is 200. Specify the -Dcom.linecorp.armeria.numCommonBlockingTaskThreads=<integer> JVM option to override the default value.
  - defaultMaxRequestLength
```
public static long defaultMaxRequestLength()
```
    Returns the default server-side maximum length of a request. Note that this value has effect only if a user did not specify it.
    The default value of this flag is 10485760L. Specify the -Dcom.linecorp.armeria.defaultMaxRequestLength=<long> to override the default value. 0 disables the length limit.
  - defaultMaxResponseLength
```
public static long defaultMaxResponseLength()
```
    Returns the default client-side maximum length of a response. Note that this value has effect only if a user did not specify it.
    The default value of this flag is 10485760L. Specify the -Dcom.linecorp.armeria.defaultMaxResponseLength=<long> to override the default value. 0 disables the length limit.
  - defaultRequestTimeoutMillis
```
public static long defaultRequestTimeoutMillis()
```
    Returns the default server-side timeout of a request in milliseconds. Note that this value has effect only if a user did not specify it.
    The default value of this flag is 10000L. Specify the -Dcom.linecorp.armeria.defaultRequestTimeoutMillis=<long> to override the default value. 0 disables the timeout.
  - defaultResponseTimeoutMillis
```
public static long defaultResponseTimeoutMillis()
```
    Returns the default client-side timeout of a response in milliseconds. Note that this value has effect only if a user did not specify it.
    The default value of this flag is 15000L. Specify the -Dcom.linecorp.armeria.defaultResponseTimeoutMillis=<long> to override the default value. 0 disables the timeout.
  - defaultConnectTimeoutMillis
```
public static long defaultConnectTimeoutMillis()
```
    Returns the default client-side timeout of a socket connection attempt in milliseconds. Note that this value has effect only if a user did not specify it.
    The default value of this flag is 3200L. Specify the -Dcom.linecorp.armeria.defaultConnectTimeoutMillis=<integer> JVM option to override the default value.
  - defaultWriteTimeoutMillis
```
public static long defaultWriteTimeoutMillis()
```
    Returns the default client-side timeout of a socket write attempt in milliseconds. Note that this value has effect only if a user did not specify it.
    The default value of this flag is 1000L. Specify the -Dcom.linecorp.armeria.defaultWriteTimeoutMillis=<integer> JVM option to override the default value. 0 disables the timeout.
  - defaultServerIdleTimeoutMillis
```
public static long defaultServerIdleTimeoutMillis()
```
    Returns the default server-side idle timeout of a connection for keep-alive in milliseconds. Note that this value has effect only if a user did not specify it.
    The default value of this flag is 15000L. Specify the -Dcom.linecorp.armeria.defaultServerIdleTimeoutMillis=<integer> JVM option to override the default value.
  - defaultClientIdleTimeoutMillis
```
public static long defaultClientIdleTimeoutMillis()
```
    Returns the default client-side idle timeout of a connection for keep-alive in milliseconds. Note that this value has effect only if a user did not specify it.
    This default value of this flag is 10000L. Specify the -Dcom.linecorp.armeria.defaultClientIdleTimeoutMillis=<integer> JVM option to override the default value.
  - defaultHttp1MaxInitialLineLength
```
public static int defaultHttp1MaxInitialLineLength()
```
    Returns the default maximum length of an HTTP/1 response initial line. Note that this value has effect only if a user did not specify it.
    This default value of this flag is 4096. Specify the -Dcom.linecorp.armeria.defaultHttp1MaxInitialLineLength=<integer> JVM option to override the default value.
  - defaultHttp1MaxHeaderSize
```
public static int defaultHttp1MaxHeaderSize()
```
    Returns the default maximum length of all headers in an HTTP/1 response. Note that this value has effect only if a user did not specify it.
    This default value of this flag is 8192. Specify the -Dcom.linecorp.armeria.defaultHttp1MaxHeaderSize=<integer> JVM option to override the default value.
  - defaultHttp1MaxChunkSize
```
public static int defaultHttp1MaxChunkSize()
```
    Returns the default maximum length of each chunk in an HTTP/1 response content. The content or a chunk longer than this value will be split into smaller chunks so that their lengths never exceed it. Note that this value has effect only if a user did not specify it.
    The default value of this flag is 8192. Specify the -Dcom.linecorp.armeria.defaultHttp1MaxChunkSize=<integer> JVM option to override the default value.
  - defaultUseHttp2Preface
```
public static boolean defaultUseHttp2Preface()
```
    Returns the default value of the ClientFactoryBuilder.useHttp2Preface(boolean) option. Note that this value has effect only if a user did not specify it.
    This flag is enabled by default. Specify the -Dcom.linecorp.armeria.defaultUseHttp2Preface=false JVM option to disable it.
  - defaultUseHttp1Pipelining
```
public static boolean defaultUseHttp1Pipelining()
```
    Returns the default value of the ClientFactoryBuilder.useHttp1Pipelining(boolean) option. Note that this value has effect only if a user did not specify it.
    This flag is disabled by default. Specify the -Dcom.linecorp.armeria.defaultUseHttp1Pipelining=true JVM option to enable it.
  - defaultHttp2InitialConnectionWindowSize
```
public static int defaultHttp2InitialConnectionWindowSize()
```
    Returns the default value of the ServerBuilder.http2InitialConnectionWindowSize(int) and ClientFactoryBuilder.http2InitialConnectionWindowSize(int) option. Note that this value has effect only if a user did not specify it.
    The default value of this flag is 1048576. Specify the -Dcom.linecorp.armeria.defaultHttp2InitialConnectionWindowSize=<integer> JVM option to override the default value.
  - defaultHttp2InitialStreamWindowSize
```
public static int defaultHttp2InitialStreamWindowSize()
```
    Returns the default value of the ServerBuilder.http2InitialStreamWindowSize(int) and ClientFactoryBuilder.http2InitialStreamWindowSize(int) option. Note that this value has effect only if a user did not specify it.
    The default value of this flag is 1048576. Specify the -Dcom.linecorp.armeria.defaultHttp2InitialStreamWindowSize=<integer> JVM option to override the default value.
  - defaultHttp2MaxFrameSize
```
public static int defaultHttp2MaxFrameSize()
```
    Returns the default value of the ServerBuilder.http2MaxFrameSize(int) and ClientFactoryBuilder.http2MaxFrameSize(int) option. Note that this value has effect only if a user did not specify it.
    The default value of this flag is 16384. Specify the -Dcom.linecorp.armeria.defaultHttp2MaxFrameSize=<integer> JVM option to override the default value.
  - defaultHttp2MaxStreamsPerConnection
```
public static long defaultHttp2MaxStreamsPerConnection()
```
    Returns the default value of the ServerBuilder.http2MaxStreamsPerConnection(long) option. Note that this value has effect only if a user did not specify it.
    The default value of this flag is 2147483647L. Specify the -Dcom.linecorp.armeria.defaultHttp2MaxStreamsPerConnection=<integer> JVM option to override the default value.
  - defaultHttp2MaxHeaderListSize
```
public static long defaultHttp2MaxHeaderListSize()
```
    Returns the default value of the ServerBuilder.http2MaxHeaderListSize(long) and ClientFactoryBuilder.http2MaxHeaderListSize(long) option. Note that this value has effect only if a user did not specify it.
    The default value of this flag is 8192L. Specify the -Dcom.linecorp.armeria.defaultHttp2MaxHeaderListSize=<integer> JVM option to override the default value.
  - defaultBackoffSpec
```
public static String defaultBackoffSpec()
```
    Returns the default value of the backoffSpec parameter when instantiating a Backoff using Backoff.of(String). Note that this value has effect only if a user did not specify the defaultBackoffSpec in the constructor call.
    The default value of this flag is "exponential=200:10000,jitter=0.2". Specify the -Dcom.linecorp.armeria.defaultBackoffSpec=<spec> JVM option to override the default value.
  - defaultMaxTotalAttempts
```
public static int defaultMaxTotalAttempts()
```
    Returns the default maximum number of total attempts. Note that this value has effect only if a user did not specify it when creating a RetryingHttpClient or a RetryingRpcClient.
    The default value of this flag is 10. Specify the -Dcom.linecorp.armeria.defaultMaxTotalAttempts=<integer> JVM option to override the default value.
  - routeCacheSpec
```
public static Optional<String> routeCacheSpec()
```
    Returns the value of the routeCache parameter. It would be used to create a Caffeine Cache instance using CaffeineSpec for routing a request. The Cache would hold the mappings of RoutingContext and the designated ServiceConfig for a request to improve server performance.
    The default value of this flag is "maximumSize=4096". Specify the -Dcom.linecorp.armeria.routeCache=<spec> JVM option to override the default value. For example, -Dcom.linecorp.armeria.routeCache=maximumSize=4096,expireAfterAccess=600s. Also, specify -Dcom.linecorp.armeria.routeCache=off JVM option to disable it.
  - routeDecoratorCacheSpec
```
public static Optional<String> routeDecoratorCacheSpec()
```
    Returns the value of the routeDecoratorCache parameter. It would be used to create a Caffeine Cache instance using CaffeineSpec for mapping a route to decorator. The Cache would hold the mappings of RoutingContext and the designated dispatcher Services for a request to improve server performance.
    The default value of this flag is "maximumSize=4096". Specify the -Dcom.linecorp.armeria.routeDecoratorCache=<spec> JVM option to override the default value. For example, -Dcom.linecorp.armeria.routeDecoratorCache=maximumSize=4096,expireAfterAccess=600s. Also, specify -Dcom.linecorp.armeria.routeDecoratorCache=off JVM option to disable it.
  - parsedPathCacheSpec
```
public static Optional<String> parsedPathCacheSpec()
```
    Returns the value of the parsedPathCache parameter. It would be used to create a Caffeine Cache instance using CaffeineSpec for mapping raw HTTP paths to parsed pair of path and query, after validation.
    The default value of this flag is "maximumSize=4096". Specify the -Dcom.linecorp.armeria.parsedPathCache=<spec> JVM option to override the default value. For example, -Dcom.linecorp.armeria.parsedPathCache=maximumSize=4096,expireAfterAccess=600s. Also, specify -Dcom.linecorp.armeria.parsedPathCache=off JVM option to disable it.
  - headerValueCacheSpec
```
public static Optional<String> headerValueCacheSpec()
```
    Returns the value of the headerValueCache parameter. It would be used to create a Caffeine Cache instance using CaffeineSpec for mapping raw HTTP ASCII header values to String.
    The default value of this flag is "maximumSize=4096". Specify the -Dcom.linecorp.armeria.headerValueCache=<spec> JVM option to override the default value. For example, -Dcom.linecorp.armeria.headerValueCache=maximumSize=4096,expireAfterAccess=600s. Also, specify -Dcom.linecorp.armeria.headerValueCache=off JVM option to disable it.
  - fileServiceCacheSpec
```
public static Optional<String> fileServiceCacheSpec()
```
    Returns the value of the fileServiceCache parameter. It would be used to create a Caffeine Cache instance using CaffeineSpec for caching file entries.
    The default value of this flag is "maximumSize=1024". Specify the -Dcom.linecorp.armeria.fileServiceCache=<spec> JVM option to override the default value. For example, -Dcom.linecorp.armeria.fileServiceCache=maximumSize=1024,expireAfterAccess=600s. Also, specify -Dcom.linecorp.armeria.fileServiceCache=off JVM option to disable it.
  - cachedHeaders
```
public static List<String> cachedHeaders()
```
    Returns the value of the cachedHeaders parameter which contains a comma-separated list of headers whose values are cached using headerValueCache.
    The default value of this flag is ":authority,:scheme,:method,accept-encoding,content-type". Specify the -Dcom.linecorp.armeria.cachedHeaders=<csv> JVM option to override the default value.
  - compositeServiceCacheSpec
```
public static Optional<String> compositeServiceCacheSpec()
```
    Returns the value of the compositeServiceCache parameter. It would be used to create a Caffeine Cache instance using CaffeineSpec for routing a request. The Cache would hold the mappings of RoutingContext and the designated ServiceConfig for a request to improve server performance.
    The default value of this flag is "maximumSize=256". Specify the -Dcom.linecorp.armeria.compositeServiceCache=<spec> JVM option to override the default value. For example, -Dcom.linecorp.armeria.compositeServiceCache=maximumSize=256,expireAfterAccess=600s. Also, specify -Dcom.linecorp.armeria.compositeServiceCache=off JVM option to disable it.
  - annotatedServiceExceptionVerbosity
```
public static ExceptionVerbosity annotatedServiceExceptionVerbosity()
```
    Returns the verbosity of exceptions logged by annotated HTTP services. The value of this property is one of the following:
    
    ExceptionVerbosity.ALL - logging all exceptions raised from annotated HTTP services
    
    ExceptionVerbosity.UNHANDLED - logging exceptions which are not handled by ExceptionHandlers provided by a user and are not well-known exceptions
    ExceptionVerbosity.NONE - no logging exceptions
    
    A log message would be written at WARN level.
    The default value of this flag is "unhandled". Specify the -Dcom.linecorp.armeria.annotatedServiceExceptionVerbosity=<all|unhandled|none> JVM option to override the default value.
    See Also:
    
    ExceptionVerbosity
  - useJdkDnsResolver
```
public static boolean useJdkDnsResolver()
```
    Enables DefaultAddressResolverGroup that resolves domain name using JDK's built-in domain name lookup mechanism. Note that JDK's built-in resolver performs a blocking name lookup from the caller thread, and thus this flag should be enabled only when the default asynchronous resolver does not work as expected, for example by always throwing a DnsNameResolverTimeoutException.
    This flag is disabled by default. Specify the -Dcom.linecorp.armeria.useJdkDnsResolver=true JVM option to enable it.

Class Flags

Method Summary

Methods inherited from class java.lang.Object

Method Detail

verboseExceptionSampler

verboseExceptionSamplerSpec

verboseSocketExceptions

verboseResponses

useEpoll

useOpenSsl

dumpOpenSslInfo

maxNumConnections

numCommonWorkers

numCommonBlockingTaskThreads

defaultMaxRequestLength

defaultMaxResponseLength

defaultRequestTimeoutMillis

defaultResponseTimeoutMillis

defaultConnectTimeoutMillis

defaultWriteTimeoutMillis

defaultServerIdleTimeoutMillis

defaultClientIdleTimeoutMillis

defaultHttp1MaxInitialLineLength

defaultHttp1MaxHeaderSize

defaultHttp1MaxChunkSize

defaultUseHttp2Preface

defaultUseHttp1Pipelining

defaultHttp2InitialConnectionWindowSize

defaultHttp2InitialStreamWindowSize

defaultHttp2MaxFrameSize

defaultHttp2MaxStreamsPerConnection

defaultHttp2MaxHeaderListSize

defaultBackoffSpec

defaultMaxTotalAttempts

routeCacheSpec

routeDecoratorCacheSpec

parsedPathCacheSpec

headerValueCacheSpec

fileServiceCacheSpec

cachedHeaders

compositeServiceCacheSpec

annotatedServiceExceptionVerbosity

useJdkDnsResolver