impala::Statestore::TopicEntry Class Reference

Collaboration diagram for impala::Statestore::TopicEntry:

Public Types
typedef std::string	Value
	A Value is a string of bytes, for which std::string is a convenient representation. More...
typedef uint64_t	Version

Public Member Functions
void	SetValue (const Value &bytes, Version version)
	TopicEntry ()
const Value &	value () const
uint64_t	version () const
uint32_t	length () const

Static Public Attributes
static const Version	TOPIC_ENTRY_INITIAL_VERSION = 1L
	The Version value used to initialize a new TopicEntry. More...
static const Value	NULL_VALUE = ""
	Representation of an empty Value. Must have size() == 0. More...

Private Attributes
Value	value_
Version	version_

Detailed Description

A TopicEntry is a single entry in a topic, and logically is a <string, byte string> pair. If the byte string is NULL, the entry has been deleted, but may be retained to track changes to send to subscribers.

Definition at line 127 of file statestore.h.

Member Typedef Documentation

typedef std::string impala::Statestore::TopicEntry::Value

A Value is a string of bytes, for which std::string is a convenient representation.

Definition at line 130 of file statestore.h.

typedef uint64_t impala::Statestore::TopicEntry::Version

A version is a monotonically increasing counter. Each update to a topic has its own unique version with the guarantee that sequentially later updates have larger version numbers.

Definition at line 135 of file statestore.h.

Constructor & Destructor Documentation

impala::Statestore::TopicEntry::TopicEntry ( )

inline

Definition at line 149 of file statestore.h.

Member Function Documentation

uint32_t impala::Statestore::TopicEntry::length ( ) const

inline

Definition at line 153 of file statestore.h.

References value_.

void Statestore::TopicEntry::SetValue	(	const Value &	bytes,
		TopicEntry::Version	version
	)

Sets the value of this entry to the byte / length pair. NULL_VALUE implies this entry has been deleted. The caller is responsible for ensuring, if required, that the version parameter is larger than the current version() TODO: Consider enforcing version monotonicity here.

Definition at line 120 of file statestore.cc.

References NULL_VALUE.

const Value& impala::Statestore::TopicEntry::value ( ) const

inline

Definition at line 151 of file statestore.h.

References value_.

Referenced by impala::Statestore::GatherTopicUpdates().

uint64_t impala::Statestore::TopicEntry::version ( ) const

inline

Definition at line 152 of file statestore.h.

References version_.

Member Data Documentation

const Statestore::TopicEntry::Value Statestore::TopicEntry::NULL_VALUE = ""

static

Representation of an empty Value. Must have size() == 0.

Definition at line 141 of file statestore.h.

Referenced by impala::Statestore::GatherTopicUpdates(), and impala::Statestore::SendTopicUpdate().

const Version impala::Statestore::TopicEntry::TOPIC_ENTRY_INITIAL_VERSION = 1L

static

The Version value used to initialize a new TopicEntry.

Definition at line 138 of file statestore.h.

Value impala::Statestore::TopicEntry::value_

private

Byte string value, owned by this TopicEntry. The value is opaque to the statestore, and is interpreted only by subscribers.

Definition at line 158 of file statestore.h.

Referenced by length(), and value().

Version impala::Statestore::TopicEntry::version_

private

The version of this entry. Every update is assigned a monotonically increasing version number so that only the minimal set of changes can be sent from the statestore to a subscriber.

Definition at line 163 of file statestore.h.

Referenced by version().

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The documentation for this class was generated from the following files:

• be/src/statestore/statestore.h
• be/src/statestore/statestore.cc