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.
Constructors
SessionPoolOptions()
Functions
EnforceConstraints(int)
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.
| Parameter | |
|---|---|
| Name | Description |
num_channels |
int
|
| Returns | |
|---|---|
| Type | Description |
SessionPoolOptions & | |
set_min_sessions(int)
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).
| Parameter | |
|---|---|
| Name | Description |
count |
int
|
| Returns | |
|---|---|
| Type | Description |
SessionPoolOptions & | |
min_sessions() const
Return the minimum number of sessions to keep in the pool.
| Returns | |
|---|---|
| Type | Description |
int | |
set_max_sessions_per_channel(int)
Set the maximum number of sessions to create on each channel.
Values <= 1 are treated as 1.
| Parameter | |
|---|---|
| Name | Description |
count |
int
|
| Returns | |
|---|---|
| Type | Description |
SessionPoolOptions & | |
max_sessions_per_channel() const
Return the minimum number of sessions to keep in the pool.
| Returns | |
|---|---|
| Type | Description |
int | |
set_max_idle_sessions(int)
Set the maximum number of sessions to keep in the pool in an idle state.
Values <= 0 are treated as 0.
| Parameter | |
|---|---|
| Name | Description |
count |
int
|
| Returns | |
|---|---|
| Type | Description |
SessionPoolOptions & | |
max_idle_sessions() const
Return the maximum number of idle sessions to keep in the pool.
| Returns | |
|---|---|
| Type | Description |
int | |
set_action_on_exhaustion(ActionOnExhaustion)
Set whether to block or fail on pool exhaustion.
| Parameter | |
|---|---|
| Name | Description |
action |
ActionOnExhaustion
|
| Returns | |
|---|---|
| Type | Description |
SessionPoolOptions & | |
action_on_exhaustion() const
Return the action to take (kBlock or kFail) when attempting to allocate a session when the pool is exhausted.
| Returns | |
|---|---|
| Type | Description |
ActionOnExhaustion | |
set_keep_alive_interval(std::chrono::seconds)
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.
| Parameter | |
|---|---|
| Name | Description |
interval |
std::chrono::seconds
|
| Returns | |
|---|---|
| Type | Description |
SessionPoolOptions & | |
keep_alive_interval() const
Return the interval at which we refresh sessions to prevent GC.
| Returns | |
|---|---|
| Type | Description |
std::chrono::seconds | |
set_labels(std::map< std::string, std::string >)
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.
| Parameter | |
|---|---|
| Name | Description |
labels |
std::map< std::string, std::string >
|
| Returns | |
|---|---|
| Type | Description |
SessionPoolOptions & | |
labels() const
Return the labels used when creating sessions within the pool.
| Returns | |
|---|---|
| Type | Description |
std::map< std::string, std::string > const & | |