google::cloud::spanner::SessionPoolOptions Class Reference

Controls the session pool maintained by a spanner::Client. More...

#include <google/cloud/spanner/session_pool_options.h>

Public Member Functions
	SessionPoolOptions ()
SessionPoolOptions &	EnforceConstraints (int num_channels)
	Enforce the stated constraints on the option values, altering them if necessary. More...
SessionPoolOptions &	set_min_sessions (int count)
	Set the minimum number of sessions to keep in the pool. More...
int	min_sessions () const
	Return the minimum number of sessions to keep in the pool. More...
SessionPoolOptions &	set_max_sessions_per_channel (int count)
	Set the maximum number of sessions to create on each channel. More...
int	max_sessions_per_channel () const
	Return the minimum number of sessions to keep in the pool. More...
SessionPoolOptions &	set_max_idle_sessions (int count)
	Set the maximum number of sessions to keep in the pool in an idle state. More...
int	max_idle_sessions () const
	Return the maximum number of idle sessions to keep in the pool. More...
SessionPoolOptions &	set_action_on_exhaustion (ActionOnExhaustion action)
	Set whether to block or fail on pool exhaustion. More...
ActionOnExhaustion	action_on_exhaustion () const
	Return the action to take (kBlock or kFail) when attempting to allocate a session when the pool is exhausted. More...
SessionPoolOptions &	set_keep_alive_interval (std::chrono::seconds interval)
	Set the interval at which we refresh sessions so they don't get collected by the backend GC. More...
std::chrono::seconds	keep_alive_interval () const
	Return the interval at which we refresh sessions to prevent GC. More...
SessionPoolOptions &	set_labels (std::map< std::string, std::string > labels)
	Set the labels used when creating sessions within the pool. More...
std::map< std::string, std::string > const &	labels () const
	Return the labels used when creating sessions within the pool. More...

Detailed Description

Controls the session pool maintained by a spanner::Client.

Creating Cloud Spanner sessions is an expensive operation. The recommended practice is to maintain a cache (or pool) of sessions in the client side. This class controls the initial size of this pool, and how the pool grows (or shrinks) as needed.

Note

If no sessions are available to perform an operation the client library blocks until new sessions are available (either released by other threads or allocated on-demand, depending on the active constraints). It is also possible to configure the client to fail a request when the session pool is exhausted.

Constructor & Destructor Documentation

SessionPoolOptions()

google::cloud::spanner::SessionPoolOptions::SessionPoolOptions ( )

inline

Member Function Documentation

action_on_exhaustion()

ActionOnExhaustion google::cloud::spanner::SessionPoolOptions::action_on_exhaustion ( ) const

inline

Return the action to take (kBlock or kFail) when attempting to allocate a session when the pool is exhausted.

EnforceConstraints()

SessionPoolOptions & google::cloud::spanner::SessionPoolOptions::EnforceConstraints ( int  num_channels )

inline

Enforce the stated constraints on the option values, altering them if necessary.

This can't be done in the setters, since we don't yet know the number of channels, and it would also constrain the order in which the fields must be set.

num_channels the number of RPC channels in use by the pool.

keep_alive_interval()

std::chrono::seconds google::cloud::spanner::SessionPoolOptions::keep_alive_interval ( ) const

inline

Return the interval at which we refresh sessions to prevent GC.

labels()

std::map< std::string, std::string > const & google::cloud::spanner::SessionPoolOptions::labels ( ) const

inline

Return the labels used when creating sessions within the pool.

max_idle_sessions()

int google::cloud::spanner::SessionPoolOptions::max_idle_sessions ( ) const

inline

Return the maximum number of idle sessions to keep in the pool.

max_sessions_per_channel()

int google::cloud::spanner::SessionPoolOptions::max_sessions_per_channel ( ) const

inline

Return the minimum number of sessions to keep in the pool.

min_sessions()

int google::cloud::spanner::SessionPoolOptions::min_sessions ( ) const

inline

Return the minimum number of sessions to keep in the pool.

set_action_on_exhaustion()

SessionPoolOptions & google::cloud::spanner::SessionPoolOptions::set_action_on_exhaustion ( ActionOnExhaustion  action )

inline

Set whether to block or fail on pool exhaustion.

set_keep_alive_interval()

SessionPoolOptions & google::cloud::spanner::SessionPoolOptions::set_keep_alive_interval ( std::chrono::seconds  interval )

inline

Set the interval at which we refresh sessions so they don't get collected by the backend GC.

The GC collects objects older than 60 minutes, so any duration below that (less some slack to allow the calls to be made to refresh the sessions) should suffice.

set_labels()

SessionPoolOptions & google::cloud::spanner::SessionPoolOptions::set_labels ( std::map< std::string, std::string >  labels )

inline

Set the labels used when creating sessions within the pool.

• Label keys must match [a-z]([-a-z0-9]{0,61}[a-z0-9])?.
• Label values must match ([a-z]([-a-z0-9]{0,61}[a-z0-9])?)?.
• The maximum number of labels is 64.

set_max_idle_sessions()

SessionPoolOptions & google::cloud::spanner::SessionPoolOptions::set_max_idle_sessions ( int  count )

inline

Set the maximum number of sessions to keep in the pool in an idle state.

Values <= 0 are treated as 0.

set_max_sessions_per_channel()

SessionPoolOptions & google::cloud::spanner::SessionPoolOptions::set_max_sessions_per_channel ( int  count )

inline

Set the maximum number of sessions to create on each channel.

Values <= 1 are treated as 1.

set_min_sessions()

SessionPoolOptions & google::cloud::spanner::SessionPoolOptions::set_min_sessions ( int  count )

inline

Set the minimum number of sessions to keep in the pool.

Values <= 0 are treated as 0. This value will effectively be reduced if it exceeds the overall limit on the number of sessions (max_sessions_per_channel * number of channels).