Add (remote) cache metrics (#3033)

This only applies to the CacheModule-provided caches because we don't
want to have to deal with all the various other caches. We'll want to
know the various ratios between types of cache hits/misses when
evaluating the usefulness of the remote caching.

core/src/test/java/google/registry/cache/MultilayerDomainCacheTest.java

@@ -43,11 +43,12 @@ public class MultilayerDomainCacheTest {
 
   private final SimplifiedJedisClient jedisClient = mock(SimplifiedJedisClient.class);
   private final FakeClock clock = new FakeClock();
+  private final CacheMetrics cacheMetrics = mock(CacheMetrics.class);
   private MultilayerDomainCache cache;
 
   @BeforeEach
   void beforeEach() {
-    cache = new MultilayerDomainCache(jedisClient, clock);
+    cache = new MultilayerDomainCache(jedisClient, clock, cacheMetrics);
     createTld("tld");
   }
 
@@ -59,10 +60,13 @@ public class MultilayerDomainCacheTest {
     // We should have filled the caches after one attempt to load from Valkey
     verify(jedisClient).get(Domain.class, "example.tld");
     verify(jedisClient).set(new SimplifiedJedisClient.JedisResource<>("example.tld", domain));
+    verify(cacheMetrics).recordLookup("Domain", CacheMetrics.CacheHitType.MISS);
 
     // Further loads hit the local cache
     assertThat(cache.loadByDomainName("example.tld")).hasValue(domain);
+    verify(cacheMetrics).recordLookup("Domain", CacheMetrics.CacheHitType.LOCAL);
     verifyNoMoreInteractions(jedisClient);
+    verifyNoMoreInteractions(cacheMetrics);
   }
 
   @Test
@@ -72,6 +76,8 @@ public class MultilayerDomainCacheTest {
     // We hit the Valkey cache first
     when(jedisClient.get(Domain.class, "example.tld")).thenReturn(Optional.of(domain));
     assertThat(cache.loadByDomainName("example.tld")).hasValue(domain);
+    verify(cacheMetrics).recordLookup("Domain", CacheMetrics.CacheHitType.REMOTE);
+    verifyNoMoreInteractions(cacheMetrics);
   }
 
   @Test
@@ -83,11 +89,15 @@ public class MultilayerDomainCacheTest {
 
     // This time, we don't populate the remote cache because it's prober data
     verify(jedisClient).get(Domain.class, "example.tld");
+    verify(cacheMetrics).recordLookup("Domain", CacheMetrics.CacheHitType.MISS);
     verifyNoMoreInteractions(jedisClient);
+    verifyNoMoreInteractions(cacheMetrics);
   }
 
   @Test
   void testLoad_missing() {
     assertThat(cache.loadByDomainName("nonexistent.tld")).isEmpty();
+    verify(cacheMetrics).recordLookup("Domain", CacheMetrics.CacheHitType.MISS_NONEXISTENT);
+    verifyNoMoreInteractions(cacheMetrics);
   }
 }

core/src/test/java/google/registry/cache/MultilayerHostCacheTest.java

@@ -38,11 +38,12 @@ public class MultilayerHostCacheTest {
       new JpaTestExtensions.Builder().buildIntegrationTestExtension();
 
   private final SimplifiedJedisClient jedisClient = mock(SimplifiedJedisClient.class);
+  private final CacheMetrics cacheMetrics = mock(CacheMetrics.class);
   private MultilayerHostCache cache;
 
   @BeforeEach
   void beforeEach() {
-    cache = new MultilayerHostCache(jedisClient);
+    cache = new MultilayerHostCache(jedisClient, cacheMetrics);
   }
 
   @Test
@@ -53,10 +54,13 @@ public class MultilayerHostCacheTest {
     // We should have filled the caches after one attempt to load from Valkey
     verify(jedisClient).get(Host.class, host.getRepoId());
     verify(jedisClient).set(new SimplifiedJedisClient.JedisResource<>(host.getRepoId(), host));
+    verify(cacheMetrics).recordLookup("Host", CacheMetrics.CacheHitType.MISS);
 
     // Further loads hit the local cache
     assertThat(cache.loadByRepoId(host.getRepoId())).hasValue(host);
+    verify(cacheMetrics).recordLookup("Host", CacheMetrics.CacheHitType.LOCAL);
     verifyNoMoreInteractions(jedisClient);
+    verifyNoMoreInteractions(cacheMetrics);
   }
 
   @Test
@@ -66,10 +70,14 @@ public class MultilayerHostCacheTest {
     // We hit the Valkey cache first
     when(jedisClient.get(Host.class, host.getRepoId())).thenReturn(Optional.of(host));
     assertThat(cache.loadByRepoId(host.getRepoId())).hasValue(host);
+    verify(cacheMetrics).recordLookup("Host", CacheMetrics.CacheHitType.REMOTE);
+    verifyNoMoreInteractions(cacheMetrics);
   }
 
   @Test
   void testLoad_missing() {
     assertThat(cache.loadByRepoId("nonexistent")).isEmpty();
+    verify(cacheMetrics).recordLookup("Host", CacheMetrics.CacheHitType.MISS_NONEXISTENT);
+    verifyNoMoreInteractions(cacheMetrics);
   }
 }