Use pre-allocated off-heap memory along with a page-pool

build.gradle

@@ -115,7 +115,8 @@ subprojects {
                                  "--add-exports=java.base/sun.nio.ch=ALL-UNNAMED",
                                  "--add-exports=jdk.unsupported/sun.misc=ALL-UNNAMED",
                                  "--add-exports=jdk.compiler/com.sun.tools.javac.file=ALL-UNNAMED",
-                                 "--add-exports=java.base/java.lang.reflect=ALL-UNNAMED"]
+                                 "--add-exports=java.base/java.lang.reflect=ALL-UNNAMED"
+        ]
     }
 
     compileTestJava {
@@ -260,13 +261,14 @@ subprojects {
                  "--add-opens=java.base/java.io=ALL-UNNAMED",
                  "--add-opens=java.base/java.util=ALL-UNNAMED",
                  "--add-opens=java.base/java.lang.reflect=ALL-UNNAMED",
+                "--enable-native-access=ALL-UNNAMED",
                  "-XX:+UnlockDiagnosticVMOptions",
                  "-XX:+DebugNonSafepoints",
                  //"-XX:+UseShenandoahGC",
-            //     "-Xlog:gc*=debug:file=g1.log",
-//                 "-XX:+UseZGC",
+                 "-Xlog:gc*=debug:file=g1.log",
+                 "-XX:+UseZGC",
 //                 "-XX:+ZGenerational",
-             //    "-verbose:gc",
+                 "-verbose:gc",
                  "-XX:+HeapDumpOnOutOfMemoryError",
                  //"-XX:HeapDumpPath=heapdump.hprof",
                  "-XX:+UseStringDeduplication",
@@ -285,7 +287,7 @@ subprojects {
                 /* "-XX:MaxInlineSize=500" */])
 
         minHeapSize = '5g'
-        maxHeapSize = '8g'
+        maxHeapSize = '12g'
     }
 }
 

bundles/sirix-core/src/main/java/io/sirix/access/DatabaseConfiguration.java

@@ -151,6 +151,12 @@ public static int compareStructure(final Path file) {
    */
   private DatabaseType databaseType;
 
+  /**
+   * Maximum buffer size for memory segment allocation.
+   * Default is 1GB.
+   */
+  private long maxSegmentAllocationSize = 1L << 30; // 1GB default
+
   /**
    * Constructor with the path to be set.
    *
@@ -180,6 +186,28 @@ public DatabaseType getDatabaseType() {
     return databaseType;
   }
 
+  /**
+   * Set the maximum buffer size for memory segment allocation.
+   *
+   * @param size maximum buffer size in bytes
+   * @return this {@link DatabaseConfiguration} instance
+   */
+  public DatabaseConfiguration setMaxSegmentAllocationSize(final long size) {
+    checkArgument(size > 0, "Max buffer size must be positive");
+    this.maxSegmentAllocationSize = size;
+    return this;
+  }
+
+  /**
+   * Get the maximum buffer size for memory segment allocation.
+   *
+   * @return maximum buffer size in bytes
+   */
+  public long getMaxSegmentAllocationSize() {
+    return maxSegmentAllocationSize;
+  }
+
+
   /**
    * Set unique maximum resource ID.
    *
@@ -260,6 +288,7 @@ public static void serialize(final DatabaseConfiguration config) throws SirixIOE
       jsonWriter.name("file").value(filePath);
       jsonWriter.name("ID").value(config.maxResourceID);
       jsonWriter.name("databaseType").value(config.databaseType.toString());
+      jsonWriter.name("maxSegmentAllocationSize").value(config.maxSegmentAllocationSize);
       jsonWriter.endObject();
     } catch (final IOException e) {
       throw new SirixIOException(e);
@@ -287,10 +316,13 @@ public static DatabaseConfiguration deserialize(final Path file) {
       final String databaseType = jsonReader.nextName();
       assert databaseType.equals("databaseType");
       final String type = jsonReader.nextString();
+      final String maxSegmentAllocationSizeName = jsonReader.nextName();
+      assert maxSegmentAllocationSizeName.equals("maxSegmentAllocationSize");
+      final long maxSegmentAllocationSize = jsonReader.nextLong();
       jsonReader.endObject();
       final DatabaseType dbType = DatabaseType.fromString(type)
                                               .orElseThrow(() -> new IllegalStateException("Type can not be unknown."));
-      return new DatabaseConfiguration(dbFile).setMaximumResourceID(ID).setDatabaseType(dbType);
+      return new DatabaseConfiguration(dbFile).setMaximumResourceID(ID).setDatabaseType(dbType).setMaxSegmentAllocationSize(maxSegmentAllocationSize);
     } catch (final IOException e) {
       throw new SirixIOException(e);
     }

bundles/sirix-core/src/main/java/io/sirix/access/Databases.java

@@ -3,10 +3,11 @@
 import io.sirix.api.*;
 import io.sirix.api.json.JsonResourceSession;
 import io.sirix.api.xml.XmlResourceSession;
-import io.sirix.cache.BufferManager;
+import io.sirix.cache.*;
 import io.sirix.exception.SirixIOException;
 import io.sirix.exception.SirixUsageException;
 import io.sirix.utils.LogWrapper;
+import io.sirix.utils.OS;
 import io.sirix.utils.SirixFiles;
 import org.slf4j.LoggerFactory;
 
@@ -40,7 +41,8 @@ private Databases() {
   /**
    * Buffer managers / page cache for each resource.
    */
-  private static final ConcurrentMap<Path, ConcurrentMap<Path, BufferManager>> BUFFER_MANAGERS = new ConcurrentHashMap<>();
+  private static final ConcurrentMap<Path, ConcurrentMap<Path, BufferManager>> BUFFER_MANAGERS =
+      new ConcurrentHashMap<>();
 
   /**
    * DI component that manages the database.
@@ -82,6 +84,10 @@ public static synchronized boolean createJsonDatabase(final DatabaseConfiguratio
   }
 
   private static boolean createTheDatabase(final DatabaseConfiguration dbConfig) {
+    requireNonNull(dbConfig);
+
+    initAllocator(dbConfig.getMaxSegmentAllocationSize());
+
     boolean returnVal = true;
     // if file is existing, skipping
     final var databaseFile = dbConfig.getDatabaseFile();
@@ -158,6 +164,22 @@ public static synchronized void removeDatabase(final Path dbFile) {
         bufferManagers.values().forEach(BufferManager::clearAllCaches);
       }
       SirixFiles.recursiveRemove(dbFile);
+
+      freeAllocatedMemory();
+    } else {
+      logger.warn("Database at {} could not be removed, because it is either not existing or still in use.", dbFile);
+    }
+  }
+
+  public static void freeAllocatedMemory() {
+    if (MANAGER.sessions().isEmpty()) {
+//      // If no sessions are left, we can clean up the allocator.
+//      MemorySegmentAllocator segmentAllocator =
+//          OS.isWindows() ? WindowsMemorySegmentAllocator.getInstance() : LinuxMemorySegmentAllocator.getInstance();
+//      segmentAllocator.free();
+      KeyValueLeafPagePool.getInstance().free();
+      BUFFER_MANAGERS.values()
+                     .forEach((resourcePathsToBufferManagers -> resourcePathsToBufferManagers.forEach((_, bufferManager) -> bufferManager.clearAllCaches())));
     }
   }
 
@@ -257,9 +279,20 @@ private static <M extends ResourceSession<R, W>, R extends NodeReadOnlyTrx & Nod
     if (dbConfig == null) {
       throw new IllegalStateException("Configuration may not be null!");
     }
+
+    initAllocator(dbConfig.getMaxSegmentAllocationSize());
     return databaseType.createDatabase(dbConfig, user);
   }
 
+  private static void initAllocator(long maxSegmentAllocationSize) {
+    if (MANAGER.sessions().isEmpty()) {
+      KeyValueLeafPagePool.getInstance().init(maxSegmentAllocationSize);
+//      MemorySegmentAllocator segmentAllocator =
+//          OS.isWindows() ? WindowsMemorySegmentAllocator.getInstance() : LinuxMemorySegmentAllocator.getInstance();
+//      segmentAllocator.init(maxSegmentAllocationSize);
+    }
+  }
+
   /**
    * Determines if a database already exists.
    *

bundles/sirix-core/src/main/java/io/sirix/access/LocalDatabase.java

@@ -82,7 +82,7 @@ public final class LocalDatabase<T extends ResourceSession<? extends NodeReadOnl
    */
   private final ResourceStore<T> resourceStore;
 
-  private final PathBasedPool<ResourceSession<?, ?>> resourceManagers;
+  private final PathBasedPool<ResourceSession<?, ?>> resourceSessions;
 
   /**
    * This field should be use to fetch the locks for resource managers.
@@ -102,24 +102,24 @@ public final class LocalDatabase<T extends ResourceSession<? extends NodeReadOnl
    * @param sessions           The database sessions management instance.
    * @param resourceStore      The resource store used by this database.
    * @param writeLocks         Manages the locks for resource managers.
-   * @param resourceManagers   The pool for resource managers.
+   * @param resourceSessions   The pool for resource managers.
    */
   public LocalDatabase(final TransactionManager transactionManager, final DatabaseConfiguration dbConfig,
       final PathBasedPool<Database<?>> sessions, final ResourceStore<T> resourceStore,
-      final WriteLocksRegistry writeLocks, final PathBasedPool<ResourceSession<?, ?>> resourceManagers) {
+      final WriteLocksRegistry writeLocks, final PathBasedPool<ResourceSession<?, ?>> resourceSessions) {
     this.transactionManager = transactionManager;
     this.dbConfig = requireNonNull(dbConfig);
     this.sessions = sessions;
     this.resourceStore = resourceStore;
-    this.resourceManagers = resourceManagers;
+    this.resourceSessions = resourceSessions;
     this.writeLocks = writeLocks;
     this.resourceIDsToResourceNames = Maps.synchronizedBiMap(HashBiMap.create());
     this.sessions.putObject(dbConfig.getDatabaseFile(), this);
     this.bufferManagers = Databases.getBufferManager(dbConfig.getDatabaseFile());
   }
 
-  private void addResourceToBufferManagerMapping(Path resourceFile, ResourceConfiguration resourceConfig) {
-    bufferManagers.put(resourceFile, new BufferManagerImpl(10_000, 1_000, 5_000, 50_000, 500, 20));
+  private void addResourceToBufferManagerMapping(Path resourceFile) {
+    bufferManagers.put(resourceFile, new BufferManagerImpl(500_000, 65_536 * 100, 5_000, 50_000, 500, 20));
   }
 
   @Override
@@ -148,7 +148,7 @@ private void addResourceToBufferManagerMapping(Path resourceFile, ResourceConfig
 
     // Add resource to buffer manager mapping.
     if (!bufferManagers.containsKey(resourcePath)) {
-      addResourceToBufferManagerMapping(resourcePath, resourceConfig);
+      addResourceToBufferManagerMapping(resourcePath);
     }
 
     return resourceStore.beginResourceSession(resourceConfig, bufferManagers.get(resourcePath), resourcePath);
@@ -220,7 +220,7 @@ public synchronized boolean createResource(final ResourceConfiguration resourceC
     }
 
     if (!bufferManagers.containsKey(path)) {
-      addResourceToBufferManagerMapping(path, resourceConfig);
+      addResourceToBufferManagerMapping(path);
     }
 
     return returnVal;
@@ -269,8 +269,8 @@ public synchronized Database<T> removeResource(final String name) {
         dbConfig.getDatabaseFile().resolve(DatabaseConfiguration.DatabasePaths.DATA.getFile()).resolve(name);
 
     // Check that no running resource managers / sessions are opened.
-    if (this.resourceManagers.containsAnyEntry(resourceFile)) {
-      throw new IllegalStateException("Open resource managers found, must be closed first: " + resourceManagers);
+    if (this.resourceSessions.containsAnyEntry(resourceFile)) {
+      throw new IllegalStateException("Open resource managers found, must be closed first: " + resourceSessions);
     }
 
     // If file is existing and folder is a Sirix-dataplace, delete it.
@@ -362,6 +362,9 @@ public synchronized void close() {
     // Remove from database mapping.
     this.sessions.removeObject(dbConfig.getDatabaseFile(), this);
 
+    // Free all allocated memory if it's the last database which is closed.
+    Databases.freeAllocatedMemory();
+
     // Remove lock file.
     SirixFiles.recursiveRemove(dbConfig.getDatabaseFile().resolve(DatabaseConfiguration.DatabasePaths.LOCK.getFile()));
   }

bundles/sirix-core/src/main/java/io/sirix/access/PathBasedPool.java

@@ -10,6 +10,7 @@
 import java.util.Map;
 import java.util.Set;
 import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ConcurrentMap;
 
 import static java.util.Collections.unmodifiableMap;
 
@@ -29,7 +30,7 @@ public class PathBasedPool<E> {
     /**
      * The thread safe map of objects in the pool.
      */
-    private final Map<Path, Set<E>> sessions;
+    private final ConcurrentMap<Path, Set<E>> sessions;
 
     /**
      * Default Constructor
@@ -58,6 +59,15 @@ public boolean containsAnyEntry(final Path file) {
         return this.sessions.containsKey(file);
     }
 
+    /**
+     * Checks if the pool is empty.
+     *
+     * @return {@code true} if the pool is empty, {@code false} otherwise.
+     */
+    public boolean isEmpty() {
+        return this.sessions.isEmpty();
+    }
+
     /**
      * Package private method to remove a database.
      *

bundles/sirix-core/src/main/java/io/sirix/access/ResourceConfiguration.java

@@ -31,20 +31,19 @@
 import com.google.common.base.MoreObjects;
 import com.google.gson.stream.JsonReader;
 import com.google.gson.stream.JsonWriter;
-import io.sirix.access.trx.node.HashType;
-import io.sirix.node.NodeSerializerImpl;
-import io.sirix.node.interfaces.RecordSerializer;
-import net.openhft.hashing.LongHashFunction;
-import org.checkerframework.checker.index.qual.NonNegative;
 import io.sirix.BinaryEncodingVersion;
+import io.sirix.access.trx.node.HashType;
 import io.sirix.exception.SirixIOException;
 import io.sirix.io.StorageType;
 import io.sirix.io.bytepipe.ByteHandler;
 import io.sirix.io.bytepipe.ByteHandlerKind;
 import io.sirix.io.bytepipe.ByteHandlerPipeline;
 import io.sirix.io.bytepipe.LZ4Compressor;
+import io.sirix.node.NodeSerializerImpl;
+import io.sirix.node.interfaces.RecordSerializer;
 import io.sirix.settings.VersioningType;
-import io.sirix.utils.OS;
+import net.openhft.hashing.LongHashFunction;
+import org.checkerframework.checker.index.qual.NonNegative;
 
 import java.io.FileReader;
 import java.io.FileWriter;
@@ -169,8 +168,8 @@ public static int compareStructure(final Path file) {
   /**
    * Standard storage.
    */
-  private static final StorageType STORAGE =
-      OS.isWindows() ? StorageType.FILE_CHANNEL : OS.is64Bit() ? StorageType.MEMORY_MAPPED : StorageType.FILE_CHANNEL;
+  private static final StorageType STORAGE = StorageType.FILE_CHANNEL;
+      //OS.isWindows() ? StorageType.FILE_CHANNEL : OS.is64Bit() ? StorageType.MEMORY_MAPPED : StorageType.FILE_CHANNEL;
 
   /**
    * Standard versioning approach.
@@ -709,7 +708,7 @@ public static final class Builder {
     /**
      * Determines if node history should be stored or not.
      */
-    private boolean storeNodeHistory;
+    private boolean storeNodeHistory = true;
 
     private BinaryEncodingVersion binaryEncodingVersion = BINARY_ENCODING_VERSION;
 

bundles/sirix-core/src/main/java/io/sirix/access/ResourceStoreImpl.java

@@ -61,7 +61,7 @@ public R getOpenResourceSession(final Path resourceFile) {
 
   @Override
   public void close() {
-    resourceSessions.forEach((resourceName, resourceMgr) -> resourceMgr.close());
+    resourceSessions.forEach((_, resourceSession) -> resourceSession.close());
     resourceSessions.clear();
   }
 

bundles/sirix-core/src/main/java/io/sirix/access/trx/node/AbstractNodeReadOnlyTrx.java

@@ -39,7 +39,7 @@ public abstract class AbstractNodeReadOnlyTrx<T extends NodeCursor & NodeReadOnl
   /**
    * ID of transaction.
    */
-  protected final long id;
+  protected final int id;
 
   /**
    * State of transaction including all cached stuff.
@@ -75,7 +75,7 @@ public abstract class AbstractNodeReadOnlyTrx<T extends NodeCursor & NodeReadOnl
    * @param resourceSession     The resource manager for the current transaction
    * @param itemList            Read-transaction-exclusive item list.
    */
-  protected AbstractNodeReadOnlyTrx(final @NonNegative long trxId, final @NonNull PageReadOnlyTrx pageReadTransaction,
+  protected AbstractNodeReadOnlyTrx(final @NonNegative int trxId, final @NonNull PageReadOnlyTrx pageReadTransaction,
       final @NonNull N documentNode, final InternalResourceSession<T, W> resourceSession,
       final ItemList<AtomicValue> itemList) {
     this.itemList = itemList;
@@ -196,7 +196,7 @@ public long getPathNodeKey() {
   }
 
   @Override
-  public long getId() {
+  public int getId() {
     assertNotClosed();
     return id;
   }
@@ -534,11 +534,8 @@ public boolean isClosed() {
   }
 
   @Override
-  public synchronized void close() {
+  public void close() {
     if (!isClosed) {
-      // Close own state.
-      pageReadOnlyTrx.close();
-
       // Callback on session to make sure everything is cleaned up.
       resourceSession.closeReadTransaction(id);