/*- * #%L * LmdbJava * %% * Copyright (C) 2016 - 2018 The LmdbJava Open Source Project * %% * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. * #L% */ package org.lmdbjava; import static java.util.Objects.requireNonNull; import jnr.ffi.Pointer; import jnr.ffi.provider.MemoryManager; import static org.lmdbjava.BufferProxy.MDB_VAL_STRUCT_SIZE; import static org.lmdbjava.BufferProxy.STRUCT_FIELD_OFFSET_SIZE; import static org.lmdbjava.Library.RUNTIME; /** * Represents off-heap memory holding a key and value pair. * * @param buffer type */ final class KeyVal implements AutoCloseable { private static final MemoryManager MEM_MGR = RUNTIME.getMemoryManager(); private boolean closed; private T k; private final BufferProxy proxy; private final Pointer ptrArray; private final Pointer ptrKey; private final long ptrKeyAddr; private final Pointer ptrVal; private final long ptrValAddr; private T v; KeyVal(final BufferProxy proxy) { requireNonNull(proxy); this.proxy = proxy; this.k = proxy.allocate(); this.v = proxy.allocate(); ptrKey = MEM_MGR.allocateTemporary(MDB_VAL_STRUCT_SIZE, false); ptrKeyAddr = ptrKey.address(); ptrArray = MEM_MGR.allocateTemporary(MDB_VAL_STRUCT_SIZE * 2, false); ptrVal = ptrArray.slice(0, MDB_VAL_STRUCT_SIZE); ptrValAddr = ptrVal.address(); } @Override public void close() { if (closed) { return; } closed = true; proxy.deallocate(k); proxy.deallocate(v); } T key() { return k; } void keyIn(final T key) { proxy.in(key, ptrKey, ptrKeyAddr); } T keyOut() { k = proxy.out(k, ptrKey, ptrKeyAddr); return k; } Pointer pointerKey() { return ptrKey; } Pointer pointerVal() { return ptrVal; } T val() { return v; } void valIn(final T val) { proxy.in(val, ptrVal, ptrValAddr); } void valIn(final int size) { proxy.in(v, size, ptrVal, ptrValAddr); } /** * Prepares an array suitable for presentation as the data argument to a * MDB_MULTIPLE put. * *

* The returned array is equivalent of two MDB_vals as follows: * *

*
• ptrVal1.data = pointer to the data address of passed buffer
*
• ptrVal1.size = size of each individual data element
*
• ptrVal2.data = unused
*
• ptrVal2.size = number of data elements (as passed to this method)
*