HBASE-28504 Implement eviction logic for scanners in Rest APIs to pre…

…vent scanner leakage (#5802)


Signed-off-by: Peter Somogyi <[email protected]>

hbase-rest/pom.xml

@@ -139,6 +139,10 @@
       <groupId>org.apache.commons</groupId>
       <artifactId>commons-lang3</artifactId>
     </dependency>
+    <dependency>
+      <groupId>com.github.ben-manes.caffeine</groupId>
+      <artifactId>caffeine</artifactId>
+    </dependency>
     <dependency>
       <groupId>org.slf4j</groupId>
       <artifactId>slf4j-api</artifactId>

hbase-rest/src/main/java/org/apache/hadoop/hbase/rest/Constants.java

@@ -69,6 +69,12 @@ public interface Constants {
   String REST_DNS_NAMESERVER = "hbase.rest.dns.nameserver";
   String REST_DNS_INTERFACE = "hbase.rest.dns.interface";
 
+  String REST_SCANNERCACHE_SIZE = "hbase.rest.scannercache.size";
+  final int DEFAULT_REST_SCANNERCACHE_SIZE = 10000;
+
+  String REST_SCANNERCACHE_EXPIRE_TIME = "hbase.rest.scannercache.expire.time";
+  final long DEFAULT_REST_SCANNERCACHE_EXPIRE_TIME_MS = 60 * 60 * 1000;
+
   String FILTER_CLASSES = "hbase.rest.filter.classes";
   String SCAN_START_ROW = "startrow";
   String SCAN_END_ROW = "endrow";

hbase-rest/src/main/java/org/apache/hadoop/hbase/rest/ScannerResource.java

@@ -19,11 +19,14 @@
 
 import com.fasterxml.jackson.core.JsonParseException;
 import com.fasterxml.jackson.databind.JsonMappingException;
+import com.github.benmanes.caffeine.cache.Cache;
+import com.github.benmanes.caffeine.cache.Caffeine;
+import com.github.benmanes.caffeine.cache.RemovalCause;
 import java.io.IOException;
 import java.net.URI;
-import java.util.Collections;
-import java.util.HashMap;
-import java.util.Map;
+import java.util.concurrent.TimeUnit;
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.hbase.HBaseConfiguration;
 import org.apache.hadoop.hbase.TableNotFoundException;
 import org.apache.hadoop.hbase.filter.Filter;
 import org.apache.hadoop.hbase.rest.model.ScannerModel;
@@ -46,9 +49,7 @@ public class ScannerResource extends ResourceBase {
 
   private static final Logger LOG = LoggerFactory.getLogger(ScannerResource.class);
 
-  static final Map<String, ScannerInstanceResource> scanners =
-    Collections.synchronizedMap(new HashMap<String, ScannerInstanceResource>());
-
+  private static final Cache<String, ScannerInstanceResource> scanners = setupScanners();
   TableResource tableResource;
 
   /**
@@ -59,8 +60,23 @@ public ScannerResource(TableResource tableResource) throws IOException {
     this.tableResource = tableResource;
   }
 
+  private static Cache<String, ScannerInstanceResource> setupScanners() {
+    final Configuration conf = HBaseConfiguration.create();
+
+    int size = conf.getInt(REST_SCANNERCACHE_SIZE, DEFAULT_REST_SCANNERCACHE_SIZE);
+    long evictTimeoutMs = conf.getTimeDuration(REST_SCANNERCACHE_EXPIRE_TIME,
+      DEFAULT_REST_SCANNERCACHE_EXPIRE_TIME_MS, TimeUnit.MILLISECONDS);
+
+    Cache<String, ScannerInstanceResource> cache =
+      Caffeine.newBuilder().removalListener(ScannerResource::removalListener).maximumSize(size)
+        .expireAfterAccess(evictTimeoutMs, TimeUnit.MILLISECONDS)
+        .<String, ScannerInstanceResource> build();
+
+    return cache;
+  }
+
   static boolean delete(final String id) {
-    ScannerInstanceResource instance = scanners.remove(id);
+    ScannerInstanceResource instance = scanners.asMap().remove(id);
     if (instance != null) {
       instance.generator.close();
       return true;
@@ -69,6 +85,12 @@ static boolean delete(final String id) {
     }
   }
 
+  static void removalListener(String key, ScannerInstanceResource value, RemovalCause cause) {
+    if (cause.wasEvicted()) {
+      delete(key);
+    }
+  }
+
   Response update(final ScannerModel model, final boolean replace, final UriInfo uriInfo) {
     servlet.getMetrics().incrementRequests(1);
     if (servlet.isReadOnly()) {
@@ -140,7 +162,7 @@ public Response post(final ScannerModel model, final @Context UriInfo uriInfo) {
   @Path("{scanner: .+}")
   public ScannerInstanceResource getScannerInstanceResource(final @PathParam("scanner") String id)
     throws IOException {
-    ScannerInstanceResource instance = scanners.get(id);
+    ScannerInstanceResource instance = scanners.getIfPresent(id);
     if (instance == null) {
       servlet.getMetrics().incrementFailedGetRequests(1);
       return new ScannerInstanceResource();