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chore(spanner): Auto-enable location API and dynamic channel pool for experimental hosts #12679

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chore(spanner): Auto-enable location API and dynamic channel pool for experimental hosts #12679

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chore(spanner): Auto-enable location API and dynamic channel pool for…
rahul2393 Apr 4, 2026
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78 changes: 68 additions & 10 deletions java-spanner/google-cloud-spanner/src/main/java/com/google/cloud/spanner/SpannerOptions.java
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Original file line number Diff line number Diff line change
Expand Up @@ -141,7 +141,7 @@ public class SpannerOptions extends ServiceOptions<Spanner, SpannerOptions> {

// Dynamic Channel Pool (DCP) default values and bounds
/** Default max concurrent RPCs per channel before triggering scale up. */
public static final int DEFAULT_DYNAMIC_POOL_MAX_RPC = 25;
public static final int DEFAULT_DYNAMIC_POOL_MAX_RPC = 90;

/** Default min concurrent RPCs per channel for scale down check. */
public static final int DEFAULT_DYNAMIC_POOL_MIN_RPC = 15;
Expand All @@ -150,13 +150,13 @@ public class SpannerOptions extends ServiceOptions<Spanner, SpannerOptions> {
public static final Duration DEFAULT_DYNAMIC_POOL_SCALE_DOWN_INTERVAL = Duration.ofMinutes(3);

/** Default initial number of channels for dynamic pool. */
public static final int DEFAULT_DYNAMIC_POOL_INITIAL_SIZE = 4;
public static final int DEFAULT_DYNAMIC_POOL_INITIAL_SIZE = 1;

/** Default max number of channels for dynamic pool. */
public static final int DEFAULT_DYNAMIC_POOL_MAX_CHANNELS = 10;
public static final int DEFAULT_DYNAMIC_POOL_MAX_CHANNELS = 256;

/** Default min number of channels for dynamic pool. */
public static final int DEFAULT_DYNAMIC_POOL_MIN_CHANNELS = 2;
public static final int DEFAULT_DYNAMIC_POOL_MIN_CHANNELS = 1;

/**
* Default affinity key lifetime for dynamic channel pool. This is how long to keep an affinity
Expand Down Expand Up @@ -204,6 +204,49 @@ public static GcpChannelPoolOptions createDefaultDynamicChannelPoolOptions() {
.build();
}

/**
* Merges user-provided {@link GcpChannelPoolOptions} with Spanner-specific defaults. Any value
* that the user has not explicitly set (i.e. left at the builder's default of 0 or null) will be
* filled in from {@link #createDefaultDynamicChannelPoolOptions()}.
*/
static GcpChannelPoolOptions mergeWithDefaultChannelPoolOptions(
GcpChannelPoolOptions userOptions) {
GcpChannelPoolOptions defaults = createDefaultDynamicChannelPoolOptions();
GcpChannelPoolOptions.Builder merged = GcpChannelPoolOptions.newBuilder(userOptions);
if (userOptions.getMaxSize() <= 0) {
merged.setMaxSize(defaults.getMaxSize());
}
if (userOptions.getMinSize() <= 0) {
merged.setMinSize(defaults.getMinSize());
}
if (userOptions.getInitSize() <= 0) {
merged.setInitSize(defaults.getInitSize());
}
if (userOptions.getMinRpcPerChannel() <= 0
|| userOptions.getMaxRpcPerChannel() <= 0
|| userOptions.getScaleDownInterval() == null
|| userOptions.getScaleDownInterval().isZero()) {
merged.setDynamicScaling(
userOptions.getMinRpcPerChannel() > 0
? userOptions.getMinRpcPerChannel()
: defaults.getMinRpcPerChannel(),
userOptions.getMaxRpcPerChannel() > 0
? userOptions.getMaxRpcPerChannel()
: defaults.getMaxRpcPerChannel(),
userOptions.getScaleDownInterval() != null && !userOptions.getScaleDownInterval().isZero()
? userOptions.getScaleDownInterval()
: defaults.getScaleDownInterval());
}
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@gemini-code-assist gemini-code-assist bot Apr 4, 2026

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medium

The merging logic for dynamic scaling parameters can lead to an invalid state where minRpcPerChannel is greater than maxRpcPerChannel, which will cause an IllegalArgumentException when the options are built. For example, if a user provides a custom maxRpcPerChannel of 10 but leaves minRpcPerChannel unset (0), the merged result will have minRpcPerChannel=15 (the default) and maxRpcPerChannel=10.

Consider ensuring that the merged values maintain the invariant minRpcPerChannel <= maxRpcPerChannel by capping the minimum or bumping the maximum during the merge.

if (userOptions.getAffinityKeyLifetime() == null
|| userOptions.getAffinityKeyLifetime().isZero()) {
merged.setAffinityKeyLifetime(defaults.getAffinityKeyLifetime());
}
if (userOptions.getCleanupInterval() == null || userOptions.getCleanupInterval().isZero()) {
merged.setCleanupInterval(defaults.getCleanupInterval());
}
return merged.build();
}

private final TransportChannelProvider channelProvider;
private final ChannelEndpointCacheFactory channelEndpointCacheFactory;

Expand Down Expand Up @@ -881,21 +924,29 @@ protected SpannerOptions(Builder builder) {

// Dynamic channel pooling is disabled by default.
// It is only enabled when:
// 1. enableDynamicChannelPool() was explicitly called, AND
// 1. enableDynamicChannelPool() was explicitly called (or experimentalHost is set and DCP was
// not explicitly disabled), AND
// 2. grpc-gcp extension is enabled, AND
// 3. numChannels was not explicitly set
if (builder.dynamicChannelPoolEnabled != null && builder.dynamicChannelPoolEnabled) {
// DCP was explicitly enabled, but respect numChannels if set
boolean dcpRequested =
builder.dynamicChannelPoolEnabled != null
? builder.dynamicChannelPoolEnabled
: builder.experimentalHost != null;
if (dcpRequested) {
// DCP was enabled (explicitly or via experimentalHost), but respect numChannels if set
dynamicChannelPoolEnabled = grpcGcpExtensionEnabled && !builder.numChannelsExplicitlySet;
} else {
// DCP is disabled by default, or was explicitly disabled
dynamicChannelPoolEnabled = false;
}

// Use user-provided GcpChannelPoolOptions or create Spanner-specific defaults
// Use user-provided GcpChannelPoolOptions merged with Spanner-specific defaults,
// or create Spanner-specific defaults if no custom options are provided.
// This ensures that dynamic scaling parameters (minRpcPerChannel, maxRpcPerChannel,
// scaleDownInterval) retain their defaults even when the user only customizes pool sizing.
gcpChannelPoolOptions =
builder.gcpChannelPoolOptions != null
? builder.gcpChannelPoolOptions
? mergeWithDefaultChannelPoolOptions(builder.gcpChannelPoolOptions)
: createDefaultDynamicChannelPoolOptions();

autoThrottleAdministrativeRequests = builder.autoThrottleAdministrativeRequests;
Expand Down Expand Up @@ -930,7 +981,14 @@ protected SpannerOptions(Builder builder) {
} else {
enableBuiltInMetrics = builder.enableBuiltInMetrics;
}
enableLocationApi = builder.enableLocationApi;
// Enable location API when experimental host is set, unless explicitly disabled
// via GOOGLE_SPANNER_EXPERIMENTAL_LOCATION_API=false.
if (builder.experimentalHost != null) {
String locationApiEnvValue = System.getenv(EXPERIMENTAL_LOCATION_API_ENV_VAR);
enableLocationApi = locationApiEnvValue == null || Boolean.parseBoolean(locationApiEnvValue);
} else {
enableLocationApi = builder.enableLocationApi;
}
enableEndToEndTracing = builder.enableEndToEndTracing;
monitoringHost = builder.monitoringHost;
defaultTransactionOptions = builder.defaultTransactionOptions;
Expand Down
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