concord-server: inject ProcessKeyCache interface instead of implementation to utilize singleton scope (#1247)

Author: benbroadaway

server/impl/src/main/java/com/walmartlabs/concord/server/process/queue/ProcessKeyCache.java

@@ -78,6 +78,16 @@ public ProcessKey assertKey(UUID instanceId) {
         return processKey;
     }
 
+    @Override
+    public long hitCount() {
+        return cache.stats().hitCount();
+    }
+
+    @Override
+    public long missCount() {
+        return cache.stats().missCount();
+    }
+
     private static class ProcessNotFoundException extends Exception {
 
         @Serial

server/impl/src/main/java/com/walmartlabs/concord/server/process/queue/ProcessKeyCacheGaugeModule.java

@@ -21,13 +21,14 @@
  */
 
 import com.codahale.metrics.Gauge;
-import com.google.common.cache.CacheStats;
 import com.google.inject.AbstractModule;
 import com.google.inject.Provider;
 import com.google.inject.multibindings.Multibinder;
 import com.walmartlabs.concord.server.sdk.metrics.GaugeProvider;
+import com.walmartlabs.concord.server.sdk.ProcessKeyCache;
 
-import java.util.function.Function;
+
+import java.util.function.ToLongFunction;
 
 public class ProcessKeyCacheGaugeModule extends AbstractModule {
 
@@ -36,12 +37,12 @@ protected void configure() {
         Provider<ProcessKeyCache> provider = getProvider(ProcessKeyCache.class);
 
         Multibinder<GaugeProvider> gauges = Multibinder.newSetBinder(binder(), GaugeProvider.class);
-        gauges.addBinding().toInstance(create("hit-count", provider, CacheStats::hitCount));
-        gauges.addBinding().toInstance(create("miss-count", provider, CacheStats::missCount));
+        gauges.addBinding().toInstance(create("hit-count", provider, ProcessKeyCache::hitCount));
+        gauges.addBinding().toInstance(create("miss-count", provider, ProcessKeyCache::missCount));
     }
 
-    private static GaugeProvider<Long> create(String suffix, Provider<ProcessKeyCache> provider, Function<CacheStats, Long> value) {
-        return new GaugeProvider<Long>() {
+    private static GaugeProvider<Long> create(String suffix, Provider<ProcessKeyCache> provider, ToLongFunction<ProcessKeyCache> value) {
+        return new GaugeProvider<>() {
             @Override
             public String name() {
                 return "process-key-cache-" + suffix;
@@ -50,10 +51,7 @@ public String name() {
             @Override
             public Gauge<Long> gauge() {
                 ProcessKeyCache cache = provider.get();
-                return () -> {
-                    CacheStats stats = cache.stats();
-                    return value.apply(stats);
-                };
+                return () -> value.applyAsLong(cache);
             }
         };
     }

server/impl/src/main/java/com/walmartlabs/concord/server/process/queue/ProcessQueueManager.java

@@ -32,6 +32,7 @@
 import com.walmartlabs.concord.server.process.logs.ProcessLogManager;
 import com.walmartlabs.concord.server.sdk.PartialProcessKey;
 import com.walmartlabs.concord.server.sdk.ProcessKey;
+import com.walmartlabs.concord.server.sdk.ProcessKeyCache;
 import com.walmartlabs.concord.server.sdk.ProcessStatus;
 import org.jooq.DSLContext;
 

server/sdk/src/main/java/com/walmartlabs/concord/server/sdk/ProcessKeyCache.java

@@ -27,4 +27,8 @@ public interface ProcessKeyCache {
     ProcessKey assertKey(UUID instanceId);
 
     ProcessKey get(UUID instanceId);
+
+    long hitCount();
+
+    long missCount();
 }