CommonContext (Aeron Transport Protocol)

java.lang.Object
- io.aeron.CommonContext

All Implemented Interfaces:

java.lang.AutoCloseable

Direct Known Subclasses:

Aeron.Context
```
public class CommonContext
extends java.lang.Object
implements java.lang.AutoCloseable
```
This class provides the Media Driver and client with common configuration for the Aeron directory.
Properties
- aeron.dir: Use value as directory name for Aeron buffers and status.

Field Summary

Fields
Modifier and Type	Field and Description
`static java.lang.String`	`AERON_DIR_PROP_DEFAULT` The value of the top level Aeron directory unless overridden by `aeronDirectoryName(String)`
`static java.lang.String`	`AERON_DIR_PROP_NAME` The top level Aeron directory used for communication between a Media Driver and client.
`static long`	`DEFAULT_DRIVER_TIMEOUT_MS` Timeout in which the driver is expected to respond.
`static java.lang.String`	`IPC_CHANNEL` URI used for IPC `Publication`s and `Subscription`s
`static java.lang.String`	`SPY_PREFIX` URI used for Spy `Subscription`s whereby an outgoing unicast or multicast publication can be spied on by IPC without receiving it again via the network.
`static java.lang.String`	`TERM_LENGTH_PARAM_NAME` The param name to be used for the term length as a channel URI parameter.

Constructor Summary

Constructors
Constructor and Description

CommonContext()
Create a new context with Aeron directory and delete on exit values based on the current system properties.

Constructors
Constructor and Description
`CommonContext()` Create a new context with Aeron directory and delete on exit values based on the current system properties.

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`java.lang.String`	`aeronDirectoryName()` Get the top level Aeron directory used for communication between the client and Media Driver, and the location of the data buffers.
`CommonContext`	`aeronDirectoryName(java.lang.String dirName)` Set the top level Aeron directory used for communication between the client and Media Driver, and the location of the data buffers.
`void`	`close()` Release resources used by the CommonContext.
`java.io.File`	`cncFile()` Get the command and control file.
`CommonContext`	`conclude()` This completes initialization of the CommonContext object.
`org.agrona.concurrent.UnsafeBuffer`	`countersMetaDataBuffer()` Get the buffer containing the counter meta data.
`CommonContext`	`countersMetaDataBuffer(org.agrona.concurrent.UnsafeBuffer countersMetaDataBuffer)` Set the buffer containing the counter meta data.
`org.agrona.concurrent.UnsafeBuffer`	`countersValuesBuffer()` Get the buffer containing the counters.
`CommonContext`	`countersValuesBuffer(org.agrona.concurrent.UnsafeBuffer countersValuesBuffer)` Set the buffer containing the counters
`void`	`deleteAeronDirectory()` Delete the current Aeron directory, throwing errors if not possible.
`long`	`driverTimeoutMs()` Get the driver timeout in milliseconds.
`CommonContext`	`driverTimeoutMs(long driverTimeoutMs)` Set the driver timeout in milliseconds
`static java.lang.String`	`generateRandomDirName()` Convert the default Aeron directory name to be a random name for use with embedded drivers.
`boolean`	`isDriverActive(long driverTimeoutMs, java.util.function.Consumer<java.lang.String> logHandler)` Is a media driver active in the current Aeron directory?
`static java.io.File`	`newDefaultCncFile()` Create a new command and control file in the administration directory.
`int`	`saveErrorLog(java.io.PrintStream stream)` Read the error log to a given `PrintStream`

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

- Field Detail
  - AERON_DIR_PROP_NAME
```
public static final java.lang.String AERON_DIR_PROP_NAME
```
    The top level Aeron directory used for communication between a Media Driver and client.
    
    See Also:
    
    Constant Field Values
  - AERON_DIR_PROP_DEFAULT
```
public static final java.lang.String AERON_DIR_PROP_DEFAULT
```
    The value of the top level Aeron directory unless overridden by aeronDirectoryName(String)
  - IPC_CHANNEL
```
public static final java.lang.String IPC_CHANNEL
```
    URI used for IPC Publications and Subscriptions
    
    See Also:
    
    Constant Field Values
  - SPY_PREFIX
```
public static final java.lang.String SPY_PREFIX
```
    URI used for Spy Subscriptions whereby an outgoing unicast or multicast publication can be spied on by IPC without receiving it again via the network.
    
    See Also:
    
    Constant Field Values
  - DEFAULT_DRIVER_TIMEOUT_MS
```
public static final long DEFAULT_DRIVER_TIMEOUT_MS
```
    Timeout in which the driver is expected to respond.
    
    See Also:
    
    Constant Field Values
  - TERM_LENGTH_PARAM_NAME
```
public static final java.lang.String TERM_LENGTH_PARAM_NAME
```
    The param name to be used for the term length as a channel URI parameter.
    
    See Also:
    
    Constant Field Values
- Constructor Detail
  - CommonContext
```
public CommonContext()
```
    Create a new context with Aeron directory and delete on exit values based on the current system properties.
- Method Detail
  - generateRandomDirName
```
public static java.lang.String generateRandomDirName()
```
    Convert the default Aeron directory name to be a random name for use with embedded drivers.
    
    Returns:
    
    random directory name with default directory name as base
  - conclude
```
public CommonContext conclude()
```
    This completes initialization of the CommonContext object. It is automatically called by subclasses.
    
    Returns:
    
    this Object for method chaining.
  - aeronDirectoryName
```
public java.lang.String aeronDirectoryName()
```
    Get the top level Aeron directory used for communication between the client and Media Driver, and the location of the data buffers.
    
    Returns:
    
    The top level Aeron directory.
  - aeronDirectoryName
```
public CommonContext aeronDirectoryName(java.lang.String dirName)
```
    Set the top level Aeron directory used for communication between the client and Media Driver, and the location of the data buffers.
    
    Parameters:
    
    dirName - New top level Aeron directory.
    
    Returns:
    
    this Object for method chaining.
  - newDefaultCncFile
```
public static java.io.File newDefaultCncFile()
```
    Create a new command and control file in the administration directory.
    
    Returns:
    
    The newly created File.
  - countersMetaDataBuffer
```
public org.agrona.concurrent.UnsafeBuffer countersMetaDataBuffer()
```
    Get the buffer containing the counter meta data.
    
    Returns:
    
    The buffer storing the counter meta data.
  - countersMetaDataBuffer
```
public CommonContext countersMetaDataBuffer(org.agrona.concurrent.UnsafeBuffer countersMetaDataBuffer)
```
    Set the buffer containing the counter meta data.
    
    Parameters:
    
    countersMetaDataBuffer - The new counter meta data buffer.
    
    Returns:
    
    this Object for method chaining.
  - countersValuesBuffer
```
public org.agrona.concurrent.UnsafeBuffer countersValuesBuffer()
```
    Get the buffer containing the counters.
    
    Returns:
    
    The buffer storing the counters.
  - countersValuesBuffer
```
public CommonContext countersValuesBuffer(org.agrona.concurrent.UnsafeBuffer countersValuesBuffer)
```
    Set the buffer containing the counters
    
    Parameters:
    
    countersValuesBuffer - The new counters buffer.
    
    Returns:
    
    this Object for method chaining.
  - cncFile
```
public java.io.File cncFile()
```
    Get the command and control file.
    
    Returns:
    
    The command and control file.
  - driverTimeoutMs
```
public CommonContext driverTimeoutMs(long driverTimeoutMs)
```
    Set the driver timeout in milliseconds
    
    Parameters:
    
    driverTimeoutMs - to indicate liveness of driver
    
    Returns:
    
    driver timeout in milliseconds
  - driverTimeoutMs
```
public long driverTimeoutMs()
```
    Get the driver timeout in milliseconds.
    
    Returns:
    
    driver timeout in milliseconds.
  - deleteAeronDirectory
```
public void deleteAeronDirectory()
```
    Delete the current Aeron directory, throwing errors if not possible.
  - isDriverActive
```
public boolean isDriverActive(long driverTimeoutMs,
                              java.util.function.Consumer<java.lang.String> logHandler)
```
    Is a media driver active in the current Aeron directory?
    
    Parameters:
    
    driverTimeoutMs - for the driver liveness check
    
    logHandler - for feedback as liveness checked
    
    Returns:
    
    true if a driver is active or false if not
  - saveErrorLog
```
public int saveErrorLog(java.io.PrintStream stream)
```
    Read the error log to a given PrintStream
    
    Parameters:
    
    stream - to write the error log contents to.
    
    Returns:
    
    the number of observations from the error log
  - close
```
public void close()
```
    Release resources used by the CommonContext.
    
    Specified by:
    
    close in interface java.lang.AutoCloseable

Class CommonContext

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

AERON_DIR_PROP_NAME

AERON_DIR_PROP_DEFAULT

IPC_CHANNEL

SPY_PREFIX

DEFAULT_DRIVER_TIMEOUT_MS

TERM_LENGTH_PARAM_NAME

Constructor Detail

CommonContext

Method Detail

generateRandomDirName

conclude

aeronDirectoryName

aeronDirectoryName

newDefaultCncFile

countersMetaDataBuffer

countersMetaDataBuffer

countersValuesBuffer

countersValuesBuffer

cncFile

driverTimeoutMs

driverTimeoutMs

deleteAeronDirectory

isDriverActive

saveErrorLog

close