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loadbalancer-experimental: rename ConnectionPoolStrategy -> Connectio…
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…nSelector (#3130)

Motivation:

The ConnectionPoolStrategy carries a lot of parallels with the HostSelector
abstraction, in that it's goal is to select a connection. However, the names
are dissimilar and 'Strategy' doesn't have as strong an implication of
being capable of action.

Modifications:

Rename ConnectionPoolStrategy to ConnectionSelector to make its role more
clear.
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@bryce-anderson
bryce-anderson authored Dec 6, 2024
1 parent 8f72e01 commit 69c9cb3
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Showing 14 changed files with 129 additions and 129 deletions.
30 changes: 15 additions & 15 deletions ...balancer-experimental/src/main/java/io/servicetalk/loadbalancer/ConnectionPoolPolicy.java
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Expand Up @@ -18,7 +18,7 @@
import static io.servicetalk.utils.internal.NumberUtils.ensurePositive;

/**
* Configuration of the strategy for selecting connections from a pool to the same endpoint.
* Configuration of the policy for selecting connections from a pool to the same endpoint.
*/
public abstract class ConnectionPoolPolicy {

Expand All @@ -30,7 +30,7 @@ private ConnectionPoolPolicy() {
}

/**
* A connection selection strategy that prioritizes a configurable "core" pool.
* A connection selection policy that prioritizes a configurable "core" pool.
* <p>
* This {@link ConnectionPoolPolicy} attempts to emulate the pooling behavior often seen in thread pools.
* Specifically it allows for the configuration of a "core pool" size which are intended to be long-lived.
Expand All @@ -49,11 +49,11 @@ private ConnectionPoolPolicy() {
* @return the configured {@link ConnectionPoolPolicy}.
*/
public static ConnectionPoolPolicy corePool(final int corePoolSize, final boolean forceCorePool) {
return new CorePoolStrategy(corePoolSize, forceCorePool);
return new CorePoolPolicy(corePoolSize, forceCorePool);
}

/**
* A connection selection strategy that prioritizes connection reuse.
* A connection selection policy that prioritizes connection reuse.
* <p>
* This {@link ConnectionPoolPolicy} attempts to minimize the number of connections by attempting to direct
* traffic to connections in the order they were created in linear order up until a configured quantity. After
Expand All @@ -66,7 +66,7 @@ public static ConnectionPoolPolicy linearSearch() {
}

/**
* A connection selection strategy that prioritizes connection reuse.
* A connection selection policy that prioritizes connection reuse.
* <p>
* This {@link ConnectionPoolPolicy} attempts to minimize the number of connections by attempting to direct
* traffic to connections in the order they were created in linear order up until a configured quantity. After
Expand All @@ -77,12 +77,12 @@ public static ConnectionPoolPolicy linearSearch() {
* @return the configured {@link ConnectionPoolPolicy}.
*/
public static ConnectionPoolPolicy linearSearch(int linearSearchSpace) {
return new LinearSearchStrategy(linearSearchSpace);
return new LinearSearchPolicy(linearSearchSpace);
}

/**
* A {@link ConnectionPoolPolicy} that attempts to discern between the health of individual connections.
* If individual connections have health data the P2C strategy can be used to bias traffic toward the best
* If individual connections have health data the P2C policy can be used to bias traffic toward the best
* connections. This has the following algorithm:
* - Randomly select two connections from the 'core pool' (pick-two).
* - Try to select the 'best' of the two connections.
Expand All @@ -100,7 +100,7 @@ public static ConnectionPoolPolicy p2c(int corePoolSize, boolean forceCorePool)

/**
* A {@link ConnectionPoolPolicy} that attempts to discern between the health of individual connections.
* If individual connections have health data the P2C strategy can be used to bias traffic toward the best
* If individual connections have health data the P2C policy can be used to bias traffic toward the best
* connections. This has the following algorithm:
* - Randomly select two connections from the 'core pool' (pick-two).
* - Try to select the 'best' of the two connections.
Expand All @@ -114,36 +114,36 @@ public static ConnectionPoolPolicy p2c(int corePoolSize, boolean forceCorePool)
* @return the configured {@link ConnectionPoolPolicy}.
*/
public static ConnectionPoolPolicy p2c(int maxEffort, int corePoolSize, boolean forceCorePool) {
return new P2CStrategy(maxEffort, corePoolSize, forceCorePool);
return new P2CPolicy(maxEffort, corePoolSize, forceCorePool);
}

// instance types
static final class CorePoolStrategy extends ConnectionPoolPolicy {
static final class CorePoolPolicy extends ConnectionPoolPolicy {
final int corePoolSize;
final boolean forceCorePool;

CorePoolStrategy(final int corePoolSize, final boolean forceCorePool) {
CorePoolPolicy(final int corePoolSize, final boolean forceCorePool) {
this.corePoolSize = ensurePositive(corePoolSize, "corePoolSize");
this.forceCorePool = forceCorePool;
}
}

static final class P2CStrategy extends ConnectionPoolPolicy {
static final class P2CPolicy extends ConnectionPoolPolicy {
final int maxEffort;
final int corePoolSize;
final boolean forceCorePool;

P2CStrategy(final int maxEffort, final int corePoolSize, final boolean forceCorePool) {
P2CPolicy(final int maxEffort, final int corePoolSize, final boolean forceCorePool) {
this.maxEffort = ensurePositive(maxEffort, "maxEffort");
this.corePoolSize = ensurePositive(corePoolSize, "corePoolSize");
this.forceCorePool = forceCorePool;
}
}

static final class LinearSearchStrategy extends ConnectionPoolPolicy {
static final class LinearSearchPolicy extends ConnectionPoolPolicy {
final int linearSearchSpace;

LinearSearchStrategy(int linearSearchSpace) {
LinearSearchPolicy(int linearSearchSpace) {
this.linearSearchSpace = ensurePositive(linearSearchSpace, "linearSearchSpace");
}
}
Expand Down
18 changes: 9 additions & 9 deletions .../loadbalancer/ConnectionPoolStrategy.java → ...talk/loadbalancer/ConnectionSelector.java
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Expand Up @@ -22,10 +22,10 @@
import javax.annotation.Nullable;

/**
* A strategy for selecting connections at the {@link Host} level connection pool.
* An abstraction for selecting connections at the {@link Host} level connection pool.
* @param <C> the concrete type of the connection.
*/
interface ConnectionPoolStrategy<C extends LoadBalancedConnection> {
interface ConnectionSelector<C extends LoadBalancedConnection> {

/**
* Select a connection from the ordered list of connections.
Expand All @@ -37,18 +37,18 @@ interface ConnectionPoolStrategy<C extends LoadBalancedConnection> {
C select(List<C> connections, Predicate<C> selector);

/**
* The factory of {@link ConnectionPoolStrategy} instances.
* @param <C> the least specific connection type necessary for properly implementing the strategy.
* @see ConnectionPoolStrategy for available strategies.
* The factory of {@link ConnectionSelector} instances.
* @param <C> the least specific connection type necessary for properly implementing the selector.
* @see ConnectionSelector for available strategies.
*/

interface ConnectionPoolStrategyFactory<C extends LoadBalancedConnection> {
interface ConnectionSelectorFactory<C extends LoadBalancedConnection> {

/**
* Provide an instance of the {@link ConnectionPoolStrategy} to use with a {@link Host}.
* Provide an instance of the {@link ConnectionSelector} to use with a {@link Host}.
* @param lbDescription description of the resource, used for logging purposes.
* @return an instance of the {@link ConnectionPoolStrategy} to use with a {@link Host}.
* @return an instance of the {@link ConnectionSelector} to use with a {@link Host}.
*/
ConnectionPoolStrategy<C> buildStrategy(String lbDescription);
ConnectionSelector<C> buildConnectionSelector(String lbDescription);
}
}
24 changes: 12 additions & 12 deletions ...ancer/CorePoolConnectionPoolStrategy.java → ...dbalancer/CorePoolConnectionSelector.java
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Expand Up @@ -28,7 +28,7 @@
/**
* A connection selection strategy that prioritizes a configurable "core" pool.
* <p>
* This {@link ConnectionPoolStrategy} attempts to emulate the pooling behavior often seen in thread pools.
* This {@link ConnectionSelector} attempts to emulate the pooling behavior often seen in thread pools.
* Specifically it allows for the configuration of a "core pool" size which are intended to be long-lived.
* Iteration starts in the core pool at a random position and then iterates through the entire core pool before
* moving to an overflow pool. Because iteration of this core pool starts at a random position the core connections
Expand All @@ -40,13 +40,13 @@
*
* @param <C> the concrete type of the {@link LoadBalancedConnection}.
*/
final class CorePoolConnectionPoolStrategy<C extends LoadBalancedConnection>
implements ConnectionPoolStrategy<C> {
final class CorePoolConnectionSelector<C extends LoadBalancedConnection>
implements ConnectionSelector<C> {

private final int corePoolSize;
private final boolean forceCorePool;

private CorePoolConnectionPoolStrategy(final int corePoolSize, final boolean forceCorePool) {
private CorePoolConnectionSelector(final int corePoolSize, final boolean forceCorePool) {
this.corePoolSize = ensurePositive(corePoolSize, "corePoolSize");
this.forceCorePool = forceCorePool;
}
Expand Down Expand Up @@ -83,30 +83,30 @@ public C select(List<C> connections, Predicate<C> selector) {
return null;
}

static <C extends LoadBalancedConnection> ConnectionPoolStrategyFactory<C> factory(
static <C extends LoadBalancedConnection> ConnectionSelectorFactory<C> factory(
int corePoolSize, boolean forceCorePool) {
return new CorePoolConnectionPoolStrategyFactory<>(corePoolSize, forceCorePool);
return new CorePoolConnectionSelectorFactory<>(corePoolSize, forceCorePool);
}

private static final class CorePoolConnectionPoolStrategyFactory<C extends LoadBalancedConnection>
implements ConnectionPoolStrategyFactory<C> {
private static final class CorePoolConnectionSelectorFactory<C extends LoadBalancedConnection>
implements ConnectionSelectorFactory<C> {

private final int corePoolSize;
private final boolean forceCorePool;

CorePoolConnectionPoolStrategyFactory(int corePoolSize, boolean forceCorePool) {
CorePoolConnectionSelectorFactory(int corePoolSize, boolean forceCorePool) {
this.corePoolSize = ensurePositive(corePoolSize, "corePoolSize");
this.forceCorePool = forceCorePool;
}

@Override
public ConnectionPoolStrategy<C> buildStrategy(String lbDescription) {
return new CorePoolConnectionPoolStrategy<>(corePoolSize, forceCorePool);
public ConnectionSelector<C> buildConnectionSelector(String lbDescription) {
return new CorePoolConnectionSelector<>(corePoolSize, forceCorePool);
}

@Override
public String toString() {
return "CorePoolConnectionPoolStrategyFactory{" +
return CorePoolConnectionSelectorFactory.class.getSimpleName() + "{" +
"corePoolSize=" + corePoolSize +
", forceCorePool=" + forceCorePool +
'}';
Expand Down
8 changes: 4 additions & 4 deletions ...talk-loadbalancer-experimental/src/main/java/io/servicetalk/loadbalancer/DefaultHost.java
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Expand Up @@ -85,7 +85,7 @@ private enum State {
private final Addr address;
@Nullable
private final HealthCheckConfig healthCheckConfig;
private final ConnectionPoolStrategy<C> connectionPoolStrategy;
private final ConnectionSelector<C> connectionSelector;
@Nullable
private final HealthIndicator<Addr, C> healthIndicator;
private final LoadBalancerObserver.HostObserver hostObserver;
Expand All @@ -94,14 +94,14 @@ private enum State {
private volatile ConnState connState = new ConnState(emptyList(), State.ACTIVE, 0, null);

DefaultHost(final String lbDescription, final Addr address,
final ConnectionPoolStrategy<C> connectionPoolStrategy,
final ConnectionSelector<C> connectionSelector,
final ConnectionFactory<Addr, ? extends C> connectionFactory,
final HostObserver hostObserver, @Nullable final HealthCheckConfig healthCheckConfig,
@Nullable final HealthIndicator<Addr, C> healthIndicator) {
this.lbDescription = requireNonNull(lbDescription, "lbDescription");
this.address = requireNonNull(address, "address");
this.healthIndicator = healthIndicator;
this.connectionPoolStrategy = requireNonNull(connectionPoolStrategy, "connectionPoolStrategy");
this.connectionSelector = requireNonNull(connectionSelector, "connectionSelector");
requireNonNull(connectionFactory, "connectionFactory");
this.connectionFactory = healthIndicator == null ? connectionFactory :
new InstrumentedConnectionFactory<>(connectionFactory, healthIndicator);
Expand Down Expand Up @@ -181,7 +181,7 @@ public boolean markExpired() {
@Nullable
public C pickConnection(Predicate<C> selector, @Nullable final ContextMap context) {
final List<C> connections = connState.connections;
return connectionPoolStrategy.select(connections, selector);
return connectionSelector.select(connections, selector);
}

@Override
Expand Down
12 changes: 6 additions & 6 deletions ...dbalancer-experimental/src/main/java/io/servicetalk/loadbalancer/DefaultLoadBalancer.java
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Original file line number Diff line number Diff line change
Expand Up @@ -109,7 +109,7 @@ final class DefaultLoadBalancer<ResolvedAddress, C extends LoadBalancedConnectio
private final Processor<Object, Object> eventStreamProcessor = newPublisherProcessorDropHeadOnOverflow(32);
private final Publisher<Object> eventStream;
private final SequentialCancellable discoveryCancellable = new SequentialCancellable();
private final ConnectionPoolStrategy<C> connectionPoolStrategy;
private final ConnectionSelector<C> connectionSelector;
private final ConnectionFactory<ResolvedAddress, ? extends C> connectionFactory;
private final int randomSubsetSize;
@Nullable
Expand All @@ -130,7 +130,7 @@ final class DefaultLoadBalancer<ResolvedAddress, C extends LoadBalancedConnectio
* @param priorityStrategyFactory a builder of the {@link HostPriorityStrategy} to use with the load balancer.
* @param loadBalancingPolicy a factory of the initial host selector to use with this load balancer.
* @param randomSubsetSize the maximum number of health hosts to use when load balancing.
* @param connectionPoolStrategyFactory factory of the connection pool strategy to use with this load balancer.
* @param connectionSelectorFactory factory of the connection pool strategy to use with this load balancer.
* @param connectionFactory a function which creates new connections.
* @param loadBalancerObserverFactory factory used to build a {@link LoadBalancerObserver} to use with this
* load balancer.
Expand All @@ -146,7 +146,7 @@ final class DefaultLoadBalancer<ResolvedAddress, C extends LoadBalancedConnectio
final Function<String, HostPriorityStrategy> priorityStrategyFactory,
final LoadBalancingPolicy<ResolvedAddress, C> loadBalancingPolicy,
final int randomSubsetSize,
final ConnectionPoolStrategy.ConnectionPoolStrategyFactory<C> connectionPoolStrategyFactory,
final ConnectionSelector.ConnectionSelectorFactory<C> connectionSelectorFactory,
final ConnectionFactory<ResolvedAddress, ? extends C> connectionFactory,
final LoadBalancerObserverFactory loadBalancerObserverFactory,
@Nullable final HealthCheckConfig healthCheckConfig,
Expand All @@ -157,8 +157,8 @@ final class DefaultLoadBalancer<ResolvedAddress, C extends LoadBalancedConnectio
.buildSelector(Collections.emptyList(), lbDescription);
this.priorityStrategy = requireNonNull(
priorityStrategyFactory, "priorityStrategyFactory").apply(lbDescription);
this.connectionPoolStrategy = requireNonNull(connectionPoolStrategyFactory,
"connectionPoolStrategyFactory").buildStrategy(lbDescription);
this.connectionSelector = requireNonNull(connectionSelectorFactory,
"connectionSelectorFactory").buildConnectionSelector(lbDescription);
this.eventPublisher = requireNonNull(eventPublisher);
this.eventStream = fromSource(eventStreamProcessor)
.replay(1); // Allow for multiple subscribers and provide new subscribers with last signal.
Expand Down Expand Up @@ -427,7 +427,7 @@ private PrioritizedHostImpl<ResolvedAddress, C> createHost(ServiceDiscovererEven
final HealthCheckConfig hostHealthCheckConfig =
healthCheckConfig == null || healthCheckConfig.failedThreshold < 0 ? null : healthCheckConfig;
final PrioritizedHostImpl<ResolvedAddress, C> host = new PrioritizedHostImpl<>(
new DefaultHost<>(lbDescription, addr, connectionPoolStrategy,
new DefaultHost<>(lbDescription, addr, connectionSelector,
connectionFactory, hostObserver, hostHealthCheckConfig, indicator),
eventWeight(event), eventPriority(event));
if (indicator != null) {
Expand Down
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