#include <lb_policy.h>

Inheritance diagram for grpc_core::LoadBalancingPolicy:

[legend]

Classes
struct	Args
	Args used to instantiate an LB policy. More...

class	BackendMetricAccessor

class	CallState

class	ChannelControlHelper

class	Config

class	MetadataInterface

struct	PickArgs
	Arguments used when picking a subchannel for a call. More...

struct	PickResult
	The result of picking a subchannel for a call. More...

class	QueuePicker

class	SubchannelCallTrackerInterface

class	SubchannelPicker

class	TransientFailurePicker

struct	UpdateArgs

Public Member Functions
virtual void	ExitIdleLocked ()

grpc_pollset_set *	interested_parties () const

	LoadBalancingPolicy (Args args, intptr_t initial_refcount=1)

	LoadBalancingPolicy (const LoadBalancingPolicy &)=delete

virtual const char *	name () const =0
	Returns the name of the LB policy. More...

LoadBalancingPolicy &	operator= (const LoadBalancingPolicy &)=delete

void	Orphan () override

virtual void	ResetBackoffLocked ()=0
	Resets connection backoff. More...

virtual void	UpdateLocked (UpdateArgs)=0

	~LoadBalancingPolicy () override

Public Member Functions inherited from grpc_core::InternallyRefCounted< LoadBalancingPolicy >
	InternallyRefCounted (const InternallyRefCounted &)=delete

InternallyRefCounted &	operator= (const InternallyRefCounted &)=delete

Public Member Functions inherited from grpc_core::Orphanable
Orphanable &	operator= (const Orphanable &)=delete

	Orphanable (const Orphanable &)=delete

Protected Member Functions
ChannelControlHelper *	channel_control_helper () const

virtual void	ShutdownLocked ()=0
	Shuts down the policy. More...

std::shared_ptr< WorkSerializer >	work_serializer () const

Protected Member Functions inherited from grpc_core::InternallyRefCounted< LoadBalancingPolicy >
	InternallyRefCounted (const char *trace=nullptr, intptr_t initial_refcount=1)

RefCountedPtr< LoadBalancingPolicy >	Ref () GRPC_MUST_USE_RESULT

RefCountedPtr< LoadBalancingPolicy >	Ref (const DebugLocation &location, const char *reason) GRPC_MUST_USE_RESULT

void	Unref ()

void	Unref (const DebugLocation &location, const char *reason)

	~InternallyRefCounted () override=default

Protected Member Functions inherited from grpc_core::Orphanable
	Orphanable ()

virtual	~Orphanable ()

Private Attributes
std::unique_ptr< ChannelControlHelper >	channel_control_helper_
	Channel control helper. More...

grpc_pollset_set *	interested_parties_
	Owned pointer to interested parties in load balancing decisions. More...

std::shared_ptr< WorkSerializer >	work_serializer_
	Work Serializer under which LB policy actions take place. More...

Detailed Description

Interface for load balancing policies.

The following concepts are used here:

Channel: An abstraction that manages connections to backend servers on behalf of a client application. The application creates a channel for a given server name and then sends calls (RPCs) on it, and the channel figures out which backend server to send each call to. A channel contains a resolver, a load balancing policy (or a tree of LB policies), and a set of one or more subchannels.

Subchannel: A subchannel represents a connection to one backend server. The LB policy decides which subchannels to create, manages the connectivity state of those subchannels, and decides which subchannel to send any given call to.

Resolver: A plugin that takes a gRPC server URI and resolves it to a list of one or more addresses and a service config, as described in https://github.com/grpc/grpc/blob/master/doc/naming.md. See resolver.h for the resolver API.

Load Balancing (LB) Policy: A plugin that takes a list of addresses from the resolver, maintains and manages a subchannel for each backend address, and decides which subchannel to send each call on. An LB policy has two parts:

A LoadBalancingPolicy, which deals with the control plane work of managing subchannels.
A SubchannelPicker, which handles the data plane work of determining which subchannel a given call should be sent on. LoadBalacingPolicy API.

Note: All methods with a "Locked" suffix must be called from the work_serializer passed to the constructor.

Any I/O done by the LB policy should be done under the pollset_set returned by interested_parties().

Definition at line 95 of file lb_policy.h.

Constructor & Destructor Documentation

◆ LoadBalancingPolicy() [1/2]

grpc_core::LoadBalancingPolicy::LoadBalancingPolicy	(	Args	args,
		intptr_t	initial_refcount = `1`
	)

explicit

Definition at line 36 of file lb_policy.cc.

◆ ~LoadBalancingPolicy()

grpc_core::LoadBalancingPolicy::~LoadBalancingPolicy ( )

override

Definition at line 46 of file lb_policy.cc.

◆ LoadBalancingPolicy() [2/2]

grpc_core::LoadBalancingPolicy::LoadBalancingPolicy ( const LoadBalancingPolicy & )

delete

Member Function Documentation

◆ channel_control_helper()

ChannelControlHelper* grpc_core::LoadBalancingPolicy::channel_control_helper ( ) const

inlineprotected

Definition at line 426 of file lb_policy.h.

◆ ExitIdleLocked()

virtual void grpc_core::LoadBalancingPolicy::ExitIdleLocked ( )

inlinevirtual

Tries to enter a READY connectivity state. This is a no-op by default, since most LB policies never go into IDLE state.

Reimplemented in grpc_core::ChildPolicyHandler.

Definition at line 379 of file lb_policy.h.

◆ interested_parties()

grpc_pollset_set* grpc_core::LoadBalancingPolicy::interested_parties ( ) const

inline

Definition at line 384 of file lb_policy.h.

◆ name()

virtual const char* grpc_core::LoadBalancingPolicy::name ( ) const

pure virtual

Returns the name of the LB policy.

Implemented in grpc_core::ChildPolicyHandler.

◆ operator=()

LoadBalancingPolicy& grpc_core::LoadBalancingPolicy::operator= ( const LoadBalancingPolicy & )

delete

◆ Orphan()

void grpc_core::LoadBalancingPolicy::Orphan ( )

overridevirtual

Implements grpc_core::Orphanable.

Definition at line 50 of file lb_policy.cc.

◆ ResetBackoffLocked()

virtual void grpc_core::LoadBalancingPolicy::ResetBackoffLocked ( )

pure virtual

Resets connection backoff.

Implemented in grpc_core::ChildPolicyHandler.

◆ ShutdownLocked()

virtual void grpc_core::LoadBalancingPolicy::ShutdownLocked ( )

protectedpure virtual

Shuts down the policy.

Implemented in grpc_core::ChildPolicyHandler.

◆ UpdateLocked()

virtual void grpc_core::LoadBalancingPolicy::UpdateLocked ( UpdateArgs )

pure virtual

Updates the policy with new data from the resolver. Will be invoked immediately after LB policy is constructed, and then again whenever the resolver returns a new result.

Implemented in grpc_core::ChildPolicyHandler.

◆ work_serializer()

std::shared_ptr<WorkSerializer> grpc_core::LoadBalancingPolicy::work_serializer ( ) const

inlineprotected

Definition at line 420 of file lb_policy.h.

Member Data Documentation

◆ channel_control_helper_

std::unique_ptr<ChannelControlHelper> grpc_core::LoadBalancingPolicy::channel_control_helper_

private

Channel control helper.

Definition at line 439 of file lb_policy.h.

◆ interested_parties_

grpc_pollset_set* grpc_core::LoadBalancingPolicy::interested_parties_

private

Owned pointer to interested parties in load balancing decisions.

Definition at line 437 of file lb_policy.h.

◆ work_serializer_

std::shared_ptr<WorkSerializer> grpc_core::LoadBalancingPolicy::work_serializer_

private

Work Serializer under which LB policy actions take place.

Definition at line 435 of file lb_policy.h.

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

Classes

Public Member Functions

Protected Member Functions

Private Attributes

Detailed Description

Constructor & Destructor Documentation

◆ LoadBalancingPolicy() [1/2]

◆ ~LoadBalancingPolicy()

◆ LoadBalancingPolicy() [2/2]

Member Function Documentation

◆ channel_control_helper()

◆ ExitIdleLocked()

◆ interested_parties()

◆ name()

◆ operator=()

◆ Orphan()

◆ ResetBackoffLocked()

◆ ShutdownLocked()

◆ UpdateLocked()

◆ work_serializer()

Member Data Documentation

◆ channel_control_helper_

◆ interested_parties_

◆ work_serializer_