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Documentation

Index

• type CheckpointPaths
• type ExecutionError
• type InputFilePaths
• type InputReader
• type OutputFilePaths
• type OutputReader
• type OutputWriter
• type RawOutputPaths

Types

type CheckpointPaths

type CheckpointPaths interface {
	// GetPreviousCheckpointsPrefix returns the storage prefix for checkpoints for the previous iteration / attempt.
	// It is optional and can be an empty string in some cases
	GetPreviousCheckpointsPrefix() storage.DataReference
	// GetCheckpointPrefix returns the storage prefix that should be used to store checkpoints for the current attempt
	// The path is not accessible to Kozmo backend and are stored in the users raw path
	GetCheckpointPrefix() storage.DataReference
}

CheckpointPaths provides the paths / keys to input Checkpoints directory and an output checkpoints directory.

type ExecutionError

type ExecutionError struct {
	// Core error structure
	*core.ExecutionError
	// Indicates if this error is recoverable
	IsRecoverable bool
}

ExecutionError Indicates any error in executing the task

type InputFilePaths

type InputFilePaths interface {
	// GetInputPrefixPath returns the inputs file path, minus the protobuf file name.
	GetInputPrefixPath() storage.DataReference
	// GetInputPath returns a path for where the protobuf encoded inputs of type `core.LiteralMap` can be found. The returned value is an URN in the configured storage backend
	GetInputPath() storage.DataReference
}

InputFilePaths contains the different ways available for downstream systems to retrieve inputs. If using Files for IO with tasks, then the input will be written to this path. All the files are always created in a sandbox per execution

type InputReader

type InputReader interface {
	InputFilePaths
	// Get the inputs for this task as a literal map, an error is returned only in case of systemic errors.
	// No outputs or void is indicated using *core.LiteralMap -> nil
	Get(ctx context.Context) (*core.LiteralMap, error)
}

InputReader provides a method to access the inputs for a task execution within the plugin's Task Context

type OutputFilePaths

type OutputFilePaths interface {
	// RawOutputPaths are available with OutputFilePaths
	RawOutputPaths

	// CheckpointPaths that can be optionally used to checkpoint
	CheckpointPaths

	// GetOutputPrefixPath returns a path to a directory or prefix that contains all execution metadata for this execution
	GetOutputPrefixPath() storage.DataReference
	// GetOutputPath returns a fully qualified path (URN) to where the framework expects the output to exist in the configured storage backend
	GetOutputPath() storage.DataReference
	// GetDeckPath returns a fully qualified path (URN) to where the framework expects the deck.html to exist in the configured storage backend
	GetDeckPath() storage.DataReference
	// GetErrorPath returns a fully qualified path (URN) where the error information should be placed as a protobuf core.ErrorDocument. It is not directly
	// used by the framework, but could be used in the future
	GetErrorPath() storage.DataReference
}

OutputFilePaths contains and provides all paths where various meta outputs produced by the task can be placed, such that the framework can directly access them. Every path is represented using storage.DataReference -> an URN for the configured storage backend

type OutputReader

type OutputReader interface {
	// IsError returns true if an error was detected when reading the output and false if no error was detected
	IsError(ctx context.Context) (bool, error)
	// ReadError returns the error as type ExecutionError
	ReadError(ctx context.Context) (ExecutionError, error)
	// IsFile returns true if the outputs are using the OutputFilePaths specified files. If so it allows the system to
	// optimize the reads of the files
	IsFile(ctx context.Context) bool
	// Exists returns true if the output exists false otherwise
	Exists(ctx context.Context) (bool, error)
	// Read returns the output -> *core.LiteralMap (nil if void), *ExecutionError if user error when reading the output and error to indicate system problems
	Read(ctx context.Context) (*core.LiteralMap, *ExecutionError, error)
	// DeckExists checks if the deck file has been generated.
	DeckExists(ctx context.Context) (bool, error)
}

OutputReader provides an abstracted OutputReader interface. The plugins are responsible to provide the implementations for the interface. Some helper implementations can be found in ioutils

type OutputWriter

type OutputWriter interface {
	OutputFilePaths
	// Put Once the task completes, use this method to indicate the output accessor to the framework
	Put(ctx context.Context, reader OutputReader) error
}

OutputWriter provides an interface to write back the outputs to the engine.

type RawOutputPaths

type RawOutputPaths interface {
	// GetRawOutputPrefix is the prefix (blob store prefix or directory) where all data produced can be stored.
	GetRawOutputPrefix() storage.DataReference
}

RawOutputPaths is the actual path where the data produced by a task can be placed. It is completely optional. The advantage of using this path is to provide exactly once semantics. It is guaranteed that this path is unique for every new execution of a task (across retries etc) and is constant for a specific execution. As of 02/20/2020 Kozmokit generates this path randomly for S3. This structure proposes migration of this logic to KozmoPluginMachinery so that it can be used more universally outside of Kozmokit.