ISPN-14129 Memory used by a node and cache in the distribution endpoint

documentation/src/main/asciidoc/topics/json/rest_full_cache_data_distribution.json

@@ -5,14 +5,16 @@
       "127.0.0.1:44175"
     ],
     "memory_entries": 0,
-    "total_entries": 0
+    "total_entries": 0,
+    "memory_used": 528512
   },
   {
     "node_name":"NodeB",
     "node_addresses": [
       "127.0.0.1:44187"
     ],
     "memory_entries": 0,
-    "total_entries": 0
+    "total_entries": 0,
+    "memory_used": 528512
   }
 ]

documentation/src/main/asciidoc/topics/ref_rest_caches.adoc

@@ -177,6 +177,7 @@ Each element in the list represents a node. The properties are:
 * `node_addresses` is a list with all the node's physical addresses.
 * `memory_entries` the number of entries the node holds in memory belonging to the cache.
 * `total_entries` the number of entries the node has in memory and disk belonging to the cache.
+* `memory_used` the value in bytes the eviction algorithm estimates the cache occupies. Returns -1 if eviction is not enabled.
 
 [id='rest_v2_cache_mutable_attributes']
 = Retrieving all mutable cache configuration attributes

server/rest/proto.lock

@@ -77,6 +77,17 @@
                     "value": "0"
                   }
                 ]
+              },
+              {
+                "id": 5,
+                "name": "memoryUsed",
+                "type": "int64",
+                "options": [
+                  {
+                    "name": "default",
+                    "value": "0"
+                  }
+                ]
               }
             ]
           },

server/rest/src/main/java/org/infinispan/rest/distribution/CacheDistributionInfo.java

@@ -20,13 +20,15 @@ public class CacheDistributionInfo implements JsonSerialization, NodeDataDistrib
    private final List<String> addresses;
    private final long memoryEntries;
    private final long totalEntries;
+   private final long memoryUsed;
 
    @ProtoFactory
-   public CacheDistributionInfo(String name, List<String> addresses, long memoryEntries, long totalEntries) {
+   public CacheDistributionInfo(String name, List<String> addresses, long memoryEntries, long totalEntries, long memoryUsed) {
       this.name = name;
       this.addresses = addresses;
       this.memoryEntries = memoryEntries;
       this.totalEntries = totalEntries;
+      this.memoryUsed = memoryUsed;
    }
 
    @ProtoField(1)
@@ -51,20 +53,27 @@ public long totalEntries() {
       return totalEntries;
    }
 
+   @ProtoField(value = 5, defaultValue = "0")
+   public long memoryUsed() {
+      return memoryUsed;
+   }
+
    @Override
    public Json toJson() {
       return Json.object()
             .set("node_name", name)
             .set("node_addresses", Json.array(addresses.toArray()))
             .set("memory_entries", memoryEntries)
-            .set("total_entries", totalEntries);
+            .set("total_entries", totalEntries)
+            .set("memory_used", memoryUsed);
    }
 
    public static CacheDistributionInfo resolve(AdvancedCache<?, ?> cache) {
       final Stats stats = cache.getStats();
       final CacheManagerInfo manager = cache.getCacheManager().getCacheManagerInfo();
       long inMemory = stats.getApproximateEntriesInMemory();
       long total = stats.getApproximateEntries();
-      return new CacheDistributionInfo(manager.getNodeName(), manager.getPhysicalAddressesRaw(), inMemory, total);
+      return new CacheDistributionInfo(manager.getNodeName(), manager.getPhysicalAddressesRaw(), inMemory, total,
+            stats.getDataMemoryUsed());
    }
 }

server/rest/src/test/java/org/infinispan/rest/resources/CacheResourceV2Test.java

@@ -422,7 +422,8 @@ public void testCacheV2Stats() {
 
    @Test
    public void testCacheV2Distribution() {
-      String cacheJson = "{ \"distributed-cache\" : { \"statistics\":true } }";
+      String cacheJson = "{ \"distributed-cache\" : { \"statistics\":true, \"memory\" : {"
+            + "\"storage\": \"OFF_HEAP\", \"max-size\": \"1MB\" } } }";
       RestCacheClient cacheClient = client.cache("distributionCache");
 
       RestEntity jsonEntity = RestEntity.create(APPLICATION_JSON, cacheJson);
@@ -441,11 +442,15 @@ public void testCacheV2Distribution() {
 
       assertEquals(NUM_SERVERS, jsons.size());
       Pattern pattern = Pattern.compile(this.getClass().getSimpleName() + "-Node[a-zA-Z]$");
+      Map<String, Long> previousSizes = new HashMap<>();
       for (Json node : jsons) {
          assertEquals(node.at("memory_entries").asInteger(), 2);
          assertEquals(node.at("total_entries").asInteger(), 2);
          assertEquals(node.at("node_addresses").asJsonList().size(), 1);
          assertTrue(pattern.matcher(node.at("node_name").asString()).matches());
+         assertTrue(node.at("memory_used").asLong() > 0);
+
+         previousSizes.put(node.at("node_name").asString(), node.at("memory_used").asLong());
       }
 
       response = cacheClient.clear();
@@ -461,6 +466,12 @@ public void testCacheV2Distribution() {
       for (Json node : jsons) {
          assertEquals(node.at("memory_entries").asInteger(), 0);
          assertEquals(node.at("total_entries").asInteger(), 0);
+
+         // Even though the cache was cleared, it still occupies some space.
+         assertTrue(node.at("memory_used").asLong() > 0);
+
+         // But less space than before.
+         assertTrue(node.at("memory_used").asLong() < previousSizes.get(node.at("node_name").asString()));
       }
    }