CommonContext (Aeron Message Transport)

java.lang.Object
- io.aeron.CommonContext

All Implemented Interfaces:

java.lang.Cloneable

Direct Known Subclasses:

Aeron.Context, MediaDriver.Context
```
public class CommonContext
extends java.lang.Object
implements java.lang.Cloneable
```
This class provides the Media Driver and client with common configuration for the Aeron directory.
This class should have conclude() called before the methods are used or at least concludeAeronDirectory() to avoid NPEs.
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 java.lang.String`	`ALIAS_PARAM_NAME` Parameter name for channel URI param to indicate an alias for the given URI.
`static long`	`DEFAULT_DRIVER_TIMEOUT_MS` Default timeout in which the driver is expected to respond or heartbeat.
`static long`	`DRIVER_TIMEOUT_MS` Timeout in which the driver is expected to respond or heartbeat.
`static java.lang.String`	`DRIVER_TIMEOUT_PROP_NAME` Property name for driver timeout after which the driver is considered inactive.
`static java.lang.String`	`ENDPOINT_PARAM_NAME` The address and port used for a UDP channel.
`static java.lang.String`	`INITIAL_TERM_ID_PARAM_NAME` Initial term id to be used when creating an `ExclusivePublication`.
`static java.lang.String`	`INTERFACE_PARAM_NAME` The network interface via which the socket will be routed.
`static java.lang.String`	`IPC_CHANNEL` URI used for IPC `Publication`s and `Subscription`s
`static java.lang.String`	`IPC_MEDIA` Media type used for IPC shared memory from `Publication` to `Subscription` channels.
`static java.lang.String`	`LINGER_PARAM_NAME` Key for the linger timeout for a publication to wait around after draining in nanoseconds.
`static java.lang.String`	`MDC_CONTROL_MODE_DYNAMIC` Valid value for `MDC_CONTROL_MODE_PARAM_NAME` when dynamic control is desired.
`static java.lang.String`	`MDC_CONTROL_MODE_MANUAL` Valid value for `MDC_CONTROL_MODE_PARAM_NAME` when manual control is desired.
`static java.lang.String`	`MDC_CONTROL_MODE_PARAM_NAME` Key for the mode of control that such be used for multi-destination-cast semantics.
`static java.lang.String`	`MDC_CONTROL_PARAM_NAME` The param for the control channel IP address and port for multi-destination-cast semantics.
`static java.lang.String`	`MTU_LENGTH_PARAM_NAME` MTU length parameter name for using as a channel URI param.
`static int`	`NULL_SESSION_ID` Value to represent a sessionId that is not to be used.
`static java.lang.String`	`RELIABLE_STREAM_PARAM_NAME` Parameter name for channel URI param to indicate if a subscribed must be reliable or not.
`static java.lang.String`	`SESSION_ID_PARAM_NAME` Key for the session id for a publication or restricted subscription.
`static java.lang.String`	`SPARSE_PARAM_NAME` Parameter name for channel URI param to indicate if term buffers should be sparse.
`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`	`TAG_PREFIX` Qualifier for a value which is a tag for reference.
`static java.lang.String`	`TAGS_PARAM_NAME` Key for the tags for a channel
`static java.lang.String`	`TERM_ID_PARAM_NAME` Current term id to be used when creating an `ExclusivePublication`.
`static java.lang.String`	`TERM_LENGTH_PARAM_NAME` The param name to be used for the term length as a channel URI param.
`static java.lang.String`	`TERM_OFFSET_PARAM_NAME` Current term offset to be used when creating an `ExclusivePublication`.
`static java.lang.String`	`TTL_PARAM_NAME` Time To Live param for a multicast datagram.
`static java.lang.String`	`UDP_MEDIA` Media type used for UDP sockets from `Publication` to `Subscription` channels.

Constructor Summary

Constructors
Constructor and Description

CommonContext()

Constructors
Constructor and Description
`CommonContext()`

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`java.io.File`	`aeronDirectory()` Get the directory in which the aeron config files are stored.
`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.
`CommonContext`	`clone()` Perform a shallow copy of the object.
`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.
`CommonContext`	`concludeAeronDirectory()` Conclude the `aeronDirectory()` so it does not need to keep being recreated.
`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 void`	`formatError(java.io.PrintStream out, java.text.SimpleDateFormat dateFormat, int observationCount, long firstObservationTimestamp, long lastObservationTimestamp, java.lang.String encodedException)`
`static java.lang.String`	`generateRandomDirName()` Convert the default Aeron directory name to be a random name for use with embedded drivers.
`static java.lang.String`	`getAeronDirectoryName()` Get the default directory name to be used if `aeronDirectoryName(String)` is not set.
`static boolean`	`isDriverActive(java.io.File directory, long driverTimeoutMs, java.util.function.Consumer<java.lang.String> logger)` Is a media driver active in the given directory?
`boolean`	`isDriverActive(long driverTimeoutMs, java.util.function.Consumer<java.lang.String> logger)` Is a media driver active in the current Aeron directory?
`static boolean`	`isDriverActive(long driverTimeoutMs, java.util.function.Consumer<java.lang.String> logger, java.nio.ByteBuffer cncByteBuffer)` Is a media driver active in the current mapped CnC buffer? If the driver is mid start then it will wait for up to the driverTimeoutMs by checking for the cncVersion being set.
`java.nio.MappedByteBuffer`	`mapExistingCncFile(java.util.function.Consumer<java.lang.String> logger)` Map the CnC file if it exists.
`static java.io.File`	`newDefaultCncFile()` Create a new command and control file in the administration directory.
`int`	`saveErrorLog(java.io.PrintStream out)` Read the error log to a given `PrintStream`
`int`	`saveErrorLog(java.io.PrintStream out, java.nio.ByteBuffer cncByteBuffer)` Read the error log to a given `PrintStream`

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

- Field Detail
  - DRIVER_TIMEOUT_PROP_NAME
```
public static final java.lang.String DRIVER_TIMEOUT_PROP_NAME
```
    Property name for driver timeout after which the driver is considered inactive.
    
    See Also:
    
    Constant Field Values
  - DEFAULT_DRIVER_TIMEOUT_MS
```
public static final long DEFAULT_DRIVER_TIMEOUT_MS
```
    Default timeout in which the driver is expected to respond or heartbeat.
    
    See Also:
    
    Constant Field Values
  - DRIVER_TIMEOUT_MS
```
public static final long DRIVER_TIMEOUT_MS
```
    Timeout in which the driver is expected to respond or heartbeat.
  - NULL_SESSION_ID
```
public static final int NULL_SESSION_ID
```
    Value to represent a sessionId that is not to be used.
    
    See Also:
    
    Constant Field Values
  - 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_MEDIA
```
public static final java.lang.String IPC_MEDIA
```
    Media type used for IPC shared memory from Publication to Subscription channels.
    
    See Also:
    
    Constant Field Values
  - UDP_MEDIA
```
public static final java.lang.String UDP_MEDIA
```
    Media type used for UDP sockets from Publication to Subscription channels.
    
    See Also:
    
    Constant Field Values
  - 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
  - ENDPOINT_PARAM_NAME
```
public static final java.lang.String ENDPOINT_PARAM_NAME
```
    The address and port used for a UDP channel. For the publisher it is the socket to send to, for the subscriber it is the socket to receive from.
    
    See Also:
    
    Constant Field Values
  - INTERFACE_PARAM_NAME
```
public static final java.lang.String INTERFACE_PARAM_NAME
```
    The network interface via which the socket will be routed.
    
    See Also:
    
    Constant Field Values
  - INITIAL_TERM_ID_PARAM_NAME
```
public static final java.lang.String INITIAL_TERM_ID_PARAM_NAME
```
    Initial term id to be used when creating an ExclusivePublication.
    
    See Also:
    
    Constant Field Values
  - TERM_ID_PARAM_NAME
```
public static final java.lang.String TERM_ID_PARAM_NAME
```
    Current term id to be used when creating an ExclusivePublication.
    
    See Also:
    
    Constant Field Values
  - TERM_OFFSET_PARAM_NAME
```
public static final java.lang.String TERM_OFFSET_PARAM_NAME
```
    Current term offset to be used when creating an ExclusivePublication.
    
    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 param.
    
    See Also:
    
    Constant Field Values
  - MTU_LENGTH_PARAM_NAME
```
public static final java.lang.String MTU_LENGTH_PARAM_NAME
```
    MTU length parameter name for using as a channel URI param. If this is greater than the network MTU for UDP then the packet will be fragmented and can amplify the impact of loss.
    
    See Also:
    
    Constant Field Values
  - TTL_PARAM_NAME
```
public static final java.lang.String TTL_PARAM_NAME
```
    Time To Live param for a multicast datagram.
    
    See Also:
    
    Constant Field Values
  - MDC_CONTROL_PARAM_NAME
```
public static final java.lang.String MDC_CONTROL_PARAM_NAME
```
    The param for the control channel IP address and port for multi-destination-cast semantics.
    
    See Also:
    
    Constant Field Values
  - MDC_CONTROL_MODE_PARAM_NAME
```
public static final java.lang.String MDC_CONTROL_MODE_PARAM_NAME
```
    Key for the mode of control that such be used for multi-destination-cast semantics.
    
    See Also:
    
    Constant Field Values
  - MDC_CONTROL_MODE_MANUAL
```
public static final java.lang.String MDC_CONTROL_MODE_MANUAL
```
    Valid value for MDC_CONTROL_MODE_PARAM_NAME when manual control is desired.
    
    See Also:
    
    Constant Field Values
  - MDC_CONTROL_MODE_DYNAMIC
```
public static final java.lang.String MDC_CONTROL_MODE_DYNAMIC
```
    Valid value for MDC_CONTROL_MODE_PARAM_NAME when dynamic control is desired. Default value.
    
    See Also:
    
    Constant Field Values
  - SESSION_ID_PARAM_NAME
```
public static final java.lang.String SESSION_ID_PARAM_NAME
```
    Key for the session id for a publication or restricted subscription.
    
    See Also:
    
    Constant Field Values
  - LINGER_PARAM_NAME
```
public static final java.lang.String LINGER_PARAM_NAME
```
    Key for the linger timeout for a publication to wait around after draining in nanoseconds.
    
    See Also:
    
    Constant Field Values
  - RELIABLE_STREAM_PARAM_NAME
```
public static final java.lang.String RELIABLE_STREAM_PARAM_NAME
```
    Parameter name for channel URI param to indicate if a subscribed must be reliable or not. Value is boolean.
    
    See Also:
    
    Constant Field Values
  - TAGS_PARAM_NAME
```
public static final java.lang.String TAGS_PARAM_NAME
```
    Key for the tags for a channel
    
    See Also:
    
    Constant Field Values
  - TAG_PREFIX
```
public static final java.lang.String TAG_PREFIX
```
    Qualifier for a value which is a tag for reference. This prefix is use in the param value.
    
    See Also:
    
    Constant Field Values
  - SPARSE_PARAM_NAME
```
public static final java.lang.String SPARSE_PARAM_NAME
```
    Parameter name for channel URI param to indicate if term buffers should be sparse. Value is boolean.
    
    See Also:
    
    Constant Field Values
  - ALIAS_PARAM_NAME
```
public static final java.lang.String ALIAS_PARAM_NAME
```
    Parameter name for channel URI param to indicate an alias for the given URI. Value not interpreted by Aeron.
    
    See Also:
    
    Constant Field Values
- Constructor Detail
  - CommonContext
```
public CommonContext()
```
- Method Detail
  - clone
```
public CommonContext clone()
```
    Perform a shallow copy of the object.
    
    Overrides:
    
    clone in class java.lang.Object
    
    Returns:
    
    a shallow copy of the object.
  - getAeronDirectoryName
```
public static java.lang.String getAeronDirectoryName()
```
    Get the default directory name to be used if aeronDirectoryName(String) is not set. This will take the AERON_DIR_PROP_NAME if set and if not then AERON_DIR_PROP_DEFAULT.
    
    Returns:
    
    the default directory name to be used if aeronDirectoryName(String) is not set.
  - 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.
  - concludeAeronDirectory
```
public CommonContext concludeAeronDirectory()
```
    Conclude the aeronDirectory() so it does not need to keep being recreated.
    
    Returns:
    
    this for a fluent API.
  - 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.
  - aeronDirectory
```
public java.io.File aeronDirectory()
```
    Get the directory in which the aeron config files are stored.
    This is valid after a call to conclude().
    
    Returns:
    
    the directory in which the aeron config files are stored.
    
    See Also:
    
    aeronDirectoryName()
  - 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 for a fluent API.
  - 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. These counters are R/W for the driver, read only for all other users.
    
    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. Testing/internal purposes only.
    
    Parameters:
    
    countersMetaDataBuffer - The new counter meta data buffer.
    
    Returns:
    
    this for a fluent API.
  - countersValuesBuffer
```
public org.agrona.concurrent.UnsafeBuffer countersValuesBuffer()
```
    Get the buffer containing the counters. These counters are R/W for the driver, read only for all other users.
    
    Returns:
    
    The buffer storing the counters.
  - countersValuesBuffer
```
public CommonContext countersValuesBuffer(org.agrona.concurrent.UnsafeBuffer countersValuesBuffer)
```
    Set the buffer containing the counters. Testing/internal purposes only.
    
    Parameters:
    
    countersValuesBuffer - The new counters buffer.
    
    Returns:
    
    this for a fluent API.
  - 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:
    
    this for a fluent API.
  - 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.
  - mapExistingCncFile
```
public java.nio.MappedByteBuffer mapExistingCncFile(java.util.function.Consumer<java.lang.String> logger)
```
    Map the CnC file if it exists.
    
    Parameters:
    
    logger - for feedback
    
    Returns:
    
    a new mapping for the file if it exists otherwise null;
  - isDriverActive
```
public static boolean isDriverActive(java.io.File directory,
                                     long driverTimeoutMs,
                                     java.util.function.Consumer<java.lang.String> logger)
```
    Is a media driver active in the given directory?
    
    Parameters:
    
    directory - to check
    
    driverTimeoutMs - for the driver liveness check.
    
    logger - for feedback as liveness checked.
    
    Returns:
    
    true if a driver is active or false if not.
  - isDriverActive
```
public boolean isDriverActive(long driverTimeoutMs,
                              java.util.function.Consumer<java.lang.String> logger)
```
    Is a media driver active in the current Aeron directory?
    
    Parameters:
    
    driverTimeoutMs - for the driver liveness check.
    
    logger - for feedback as liveness checked.
    
    Returns:
    
    true if a driver is active or false if not.
  - isDriverActive
```
public static boolean isDriverActive(long driverTimeoutMs,
                                     java.util.function.Consumer<java.lang.String> logger,
                                     java.nio.ByteBuffer cncByteBuffer)
```
    Is a media driver active in the current mapped CnC buffer? If the driver is mid start then it will wait for up to the driverTimeoutMs by checking for the cncVersion being set.
    
    Parameters:
    
    driverTimeoutMs - for the driver liveness check.
    
    logger - for feedback as liveness checked.
    
    cncByteBuffer - for the existing CnC file.
    
    Returns:
    
    true if a driver is active or false if not.
  - saveErrorLog
```
public int saveErrorLog(java.io.PrintStream out)
```
    Read the error log to a given PrintStream
    
    Parameters:
    
    out - to write the error log contents to.
    
    Returns:
    
    the number of observations from the error log.
  - saveErrorLog
```
public int saveErrorLog(java.io.PrintStream out,
                        java.nio.ByteBuffer cncByteBuffer)
```
    Read the error log to a given PrintStream
    
    Parameters:
    
    out - to write the error log contents to.
    
    cncByteBuffer - containing the error log.
    
    Returns:
    
    the number of observations from the error log.
  - close
```
public void close()
```
    Release resources used by the CommonContext.
  - formatError
```
public static void formatError(java.io.PrintStream out,
                               java.text.SimpleDateFormat dateFormat,
                               int observationCount,
                               long firstObservationTimestamp,
                               long lastObservationTimestamp,
                               java.lang.String encodedException)
```

Class CommonContext

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

DRIVER_TIMEOUT_PROP_NAME

DEFAULT_DRIVER_TIMEOUT_MS

DRIVER_TIMEOUT_MS

NULL_SESSION_ID

AERON_DIR_PROP_NAME

AERON_DIR_PROP_DEFAULT

IPC_MEDIA

UDP_MEDIA

IPC_CHANNEL

SPY_PREFIX

ENDPOINT_PARAM_NAME

INTERFACE_PARAM_NAME

INITIAL_TERM_ID_PARAM_NAME

TERM_ID_PARAM_NAME

TERM_OFFSET_PARAM_NAME

TERM_LENGTH_PARAM_NAME

MTU_LENGTH_PARAM_NAME

TTL_PARAM_NAME

MDC_CONTROL_PARAM_NAME

MDC_CONTROL_MODE_PARAM_NAME

MDC_CONTROL_MODE_MANUAL

MDC_CONTROL_MODE_DYNAMIC

SESSION_ID_PARAM_NAME

LINGER_PARAM_NAME

RELIABLE_STREAM_PARAM_NAME

TAGS_PARAM_NAME

TAG_PREFIX

SPARSE_PARAM_NAME

ALIAS_PARAM_NAME

Constructor Detail

CommonContext

Method Detail

clone

getAeronDirectoryName

generateRandomDirName

conclude

concludeAeronDirectory

aeronDirectoryName

aeronDirectory

aeronDirectoryName

newDefaultCncFile

countersMetaDataBuffer

countersMetaDataBuffer

countersValuesBuffer

countersValuesBuffer

cncFile

driverTimeoutMs

driverTimeoutMs

deleteAeronDirectory

mapExistingCncFile

isDriverActive

isDriverActive

isDriverActive

saveErrorLog

saveErrorLog

close

formatError