Class InputPort

Non-generic base class for dataflow input ports, containing the functionality that doesn't depend on the row type.

The library user does not derive new port classes directly from InputPort, but instead creates or uses instances of the derived class InputPort<TInput>.

Note: As per normal, unless otherwise noted, the instance members are not thread-safe, and should only be accessed from the worker that the port belongs to.

Inheritance
Object
InputPort
InputPort<TInput>
Namespace: actionETL
Assembly: actionETL.dll
Syntax
public abstract class InputPort

Properties

BufferCapacity

Gets or sets the port buffer capacity, which is the recommended and maximum number of rows when taking rows synchronously in batches (instead of either asynchronously or row by row).

Increasing BufferCapacity can improve performance, but also consumes more memory. Setting BufferCapacity too large should be avoided, since it can cause the application to swap large amounts of memory out to disk, leading to drastically reduced performance.

Defaults to 256 rows. You can set the value with the AConfig configuration, using the InputPortBufferCapacity key, before the port is created. Alternatively, set this property before the worker or its siblings run, which will also override any AConfig setting. The value is automatically rounded up to the nearest power of two. Any value less than 1 will be set to the default value.

Also see PortBufferingMode, and Dataflow Blocking and Row Buffering.

Note: Reading the property is thread-safe, and any one thread can set it. Multiple threads (or workers) setting it simultaneously is not supported.

Declaration
public int BufferCapacity { get; set; }
Property Value
Type Description
Int32

The buffer capacity as number of rows.
Exceptions
Type Condition
InvalidOperationException

Cannot set BufferCapacity after workers run.

BufferingMode

Gets or sets the row buffering strategy an input port uses, i.e. whether the input port only buffers a smaller amount of rows to minimize the time the worker is stalled for input, or allows full buffering for input ports on workers that could otherwise dead-lock (typically having multiple inter-dependent inputs, e.g. MergeSortedTransform<TInputOutput>).

Defaults to Default, where the actual mode will be picked when the worker starts. The buffering mode can be set explicitly, although any attempt to change Full, as well as any attempt to change Limited to anything except Full, will be silently ignored.

Also see PortBufferingMode, and Dataflow Blocking and Row Buffering.

Note: Reading the property is thread-safe, and any one thread can set it. Multiple threads (or workers) setting it simultaneously is not supported.

Declaration
public PortBufferingMode BufferingMode { get; set; }
Property Value
Type Description
PortBufferingMode

Get or set the buffering mode. It cannot be set after either of the upstream or downstream ports become active.
Exceptions
Type Condition
InvalidOperationException

BufferingMode cannot be set after either of the upstream or downstream ports becomes active.

HasRow

Returns true if this port has at least one row available (irrespective of the port state); otherwise, false.

Declaration
public bool HasRow { get; }
Property Value
Type Description
Boolean

LinkedFrom

Returns the upstream output (or error output) port this input port is linked from, or null if it is not linked.

Note: This property is thread-safe.

Declaration
public OutputPortBase LinkedFrom { get; }
Property Value
Type Description
OutputPortBase

Locator

Gets the locator string, which represents where in the worker hierarchy this input port resides. It consists of the names of the worker system and all ancestor workers, separated by /, followed by the port type and its name, e.g.: /Extract Data/Extract Products/Read CSV Product File.Inputs[LeftInput].

Note: This property is thread-safe.

Declaration
public string Locator { get; }
Property Value
Type Description
String

The input port locator string.

Logger

Gets the logger instance for this input port, which should be used for logging messages related to this port. The logger's name is set to the Locator string of the input port, which will appear in the logged output.

This property is thread-safe.

Note: This property is thread-safe.

Declaration
public ALog Logger { get; }
Property Value
Type Description
ALog

Name

Gets the input port name.

Note: This property is thread-safe.

Declaration
public string Name { get; }
Property Value
Type Description
String

RowsTaken

Gets the number of rows taken from this input port. Note: This property is only thread-safe for other workers etc. to read after the port has completed.

Declaration
public long RowsTaken { get; }
Property Value
Type Description
Int64

State

Gets the input port state.

Note: This property is thread-safe. Also note however that unless the port is in a final state, then the state can change at any time.

Declaration
public InputPortState State { get; }
Property Value
Type Description
InputPortState

Status

Gets the progress status of the port, with descriptive information if the port failed. Also see State.

Note: This property is thread-safe. Also note however that unless the port is in a completed state, then the status can change at any time.

Declaration
public ProgressStatus Status { get; }
Property Value
Type Description
ProgressStatus

Worker

Gets the worker instance this port belongs to.

Note: This property is thread-safe.

Declaration
public WorkerBase Worker { get; }
Property Value
Type Description
WorkerBase

Methods

HasRowAsync()

Waits (if needed) until there is at least one available row, or the port is completed.

Note that this method should be used also when waiting for multiple rows with non-blocking and partially blocking ports, since this avoids waiting with rows in the buffer which could otherwise delay other ports and workers from progressing, and also increase memory use.

Declaration
public Task<bool> HasRowAsync()
Returns
Type Description
Task<Boolean>
truePort has at least one row available
falseThere are no rows available and the port has completed

SkipAllRowsAsync()

Discard all incoming rows asynchronously until completed.

Note that this method does not require ensuring sufficient rows are available before calling it.

Declaration
public async Task<bool> SkipAllRowsAsync()
Returns
Type Description
Task<Boolean>

true if the input was not already completed, otherwise false; in many scenarios the caller does not care either way, and ignores the return value.

SkipRow()

Skip one incoming row synchronously.

Note that this method requires ensuring a row is available before calling it, e.g. by calling HasRow before calling this method.

Declaration
public void SkipRow()
Exceptions
Type Condition
InvalidOperationException

Input has no row to skip.

SkipRowAsync()

Skip one incoming row asynchronously, or return if there are no rows to skip and the port is completed.

Note that this method does not require ensuring sufficient rows are available before calling it.

Declaration
public Task<bool> SkipRowAsync()
Returns
Type Description
Task<Boolean>

true if one row could be skipped, otherwise false (in which case the port will be completed).

ToLongString()

Returns a verbose description of this instance.

Note that this method is not thread-safe.

Declaration
public string ToLongString()
Returns
Type Description
String

ToString()

Returns a description of this instance.

Note: This method is thread-safe.

Declaration
public override string ToString()
Returns
Type Description
String
Overrides

TryCancel()

If the input port is not already canceled or completed, cancels it, and requests cancellation of the upstream output (or error output) port, which must stop sending data and clean up resources when it detects the cancellation. When the method returns, the input port state is either canceled or completed.

The caller should not take or skip any rows from the input port after this method returns. It is also not necessary to wait for the canceled port to complete before completing the worker (normally with a failure status), the system will do this automatically. Also see actionETL.InputPortCollection.TryCancel(System.Boolean).

Note that calling this method does not by itself cancel the worker system.

Declaration
public bool TryCancel()
Returns
Type Description
Boolean

true if the input port was not already canceled or completed; otherwise false.
Exceptions
Type Condition
InvalidOperationException

Port must be linked before canceling.

TrySkipRow()

Tries to skip one incoming row.

This method does not ensure the input port is seeing the latest rows upstream has sent. You should normally call SkipRowAsync() if this method returns false.

Declaration
public bool TrySkipRow()
Returns
Type Description
Boolean

true if one row could be skipped, otherwise false (which does not imply that the port has completed).

See Also

InputPort<TInput>