lmdbjava/src/main/java/org/lmdbjava/Txn.java at gh-267 · lmdbjava/lmdbjava · GitHub

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* 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.

package org.lmdbjava;

import static jnr.ffi.Memory.allocateDirect;

import static jnr.ffi.NativeType.ADDRESS;

import static org.lmdbjava.Env.SHOULD_CHECK;

import static org.lmdbjava.Library.LIB;

import static org.lmdbjava.Library.RUNTIME;

import static org.lmdbjava.MaskedFlag.isSet;

import static org.lmdbjava.MaskedFlag.mask;

import static org.lmdbjava.ResultCodeMapper.checkRc;

import static org.lmdbjava.Txn.State.DONE;

import static org.lmdbjava.Txn.State.READY;

import static org.lmdbjava.Txn.State.RELEASED;

import static org.lmdbjava.Txn.State.RESET;

import static org.lmdbjava.TxnFlags.MDB_RDONLY_TXN;

import jnr.ffi.Pointer;

/**

* LMDB transaction.

* @param <T> buffer type

public final class Txn<T> implements AutoCloseable {

private final KeyVal<T> keyVal;

private final Txn<T> parent;

private final BufferProxy<T> proxy;

private final Pointer ptr;

private final boolean readOnly;

private final Env<T> env;

private State state;

Txn(final Env<T> env, final Txn<T> parent, final BufferProxy<T> proxy, final TxnFlags... flags) {

this.proxy = proxy;

this.keyVal = proxy.keyVal();

final int flagsMask = mask(true, flags);

this.readOnly = isSet(flagsMask, MDB_RDONLY_TXN);

if (env.isReadOnly() && !this.readOnly) {

throw new EnvIsReadOnly();

}

this.env = env;

this.parent = parent;

if (parent != null && parent.isReadOnly() != this.readOnly) {

throw new IncompatibleParent();

}

final Pointer txnPtr = allocateDirect(RUNTIME, ADDRESS);

final Pointer txnParentPtr = parent == null ? null : parent.ptr;

checkRc(LIB.mdb_txn_begin(env.pointer(), txnParentPtr, flagsMask, txnPtr));

ptr = txnPtr.getPointer(0);

state = READY;

}

/** Aborts this transaction. */

public void abort() {

if (SHOULD_CHECK) {

env.checkNotClosed();

}

checkReady();

state = DONE;

LIB.mdb_txn_abort(ptr);

}

/**

* Closes this transaction by aborting if not already committed.

* <p>Closing the transaction will invoke {@link BufferProxy#deallocate(java.lang.Object)} for

* each read-only buffer (ie the key and value).

@Override

public void close() {

if (SHOULD_CHECK) {

env.checkNotClosed();

}

if (state == RELEASED) {

return;

}

if (state == READY) {

LIB.mdb_txn_abort(ptr);

}

keyVal.close();

state = RELEASED;

}

/** Commits this transaction. */

public void commit() {

if (SHOULD_CHECK) {

env.checkNotClosed();

}

checkReady();

state = DONE;

checkRc(LIB.mdb_txn_commit(ptr));

}

/**

* Return the transaction's ID.

* @return A transaction ID, valid if input is an active transaction

public long getId() {

if (SHOULD_CHECK) {

env.checkNotClosed();

}

return LIB.mdb_txn_id(ptr);

}

/**

* Obtains this transaction's parent.

* @return the parent transaction (may be null)

public Txn<T> getParent() {

return parent;

}

/**

* Whether this transaction is read-only.

* @return if read-only

public boolean isReadOnly() {

return readOnly;

}

/**

* Fetch the buffer which holds a read-only view of the LMDI allocated memory. Any use of this

* buffer must comply with the standard LMDB C "mdb_get" contract (ie do not modify, do not

* attempt to release the memory, do not use once the transaction or cursor closes, do not use

* after a write etc).

* @return the key buffer (never null)

public T key() {

return keyVal.key();

}

/** Renews a read-only transaction previously released by {@link #reset()}. */

public void renew() {

if (SHOULD_CHECK) {

env.checkNotClosed();

}

if (state != RESET) {

throw new NotResetException();

}

state = DONE;

checkRc(LIB.mdb_txn_renew(ptr));

state = READY;

}

/**

* Aborts this read-only transaction and resets the transaction handle so it can be reused upon

* calling {@link #renew()}.

public void reset() {

if (SHOULD_CHECK) {

env.checkNotClosed();

}

checkReadOnly();

if (state != READY && state != DONE) {

throw new ResetException();

}

state = RESET;

LIB.mdb_txn_reset(ptr);

}

/**

* Fetch the buffer which holds a read-only view of the LMDI allocated memory. Any use of this

* buffer must comply with the standard LMDB C "mdb_get" contract (ie do not modify, do not

* attempt to release the memory, do not use once the transaction or cursor closes, do not use

* after a write etc).

* @return the value buffer (never null)

public T val() {

return keyVal.val();

}

void checkReadOnly() {

if (!readOnly) {

throw new ReadOnlyRequiredException();

}

void checkReady() {

if (state != READY) {

throw new NotReadyException();

}

void checkWritesAllowed() {

if (readOnly) {

throw new ReadWriteRequiredException();

}

/**

* Return the state of the transaction.

* @return the state

State getState() {

return state;

}

KeyVal<T> kv() {

return keyVal;

}

KeyVal<T> newKeyVal() {

return proxy.keyVal();

}

Pointer pointer() {

return ptr;

}

/** Transaction must abort, has a child, or is invalid. */

public static final class BadException extends LmdbNativeException {

static final int MDB_BAD_TXN = -30_782;

private static final long serialVersionUID = 1L;

BadException() {

super(MDB_BAD_TXN, "Transaction must abort, has a child, or is invalid");

}

/** Invalid reuse of reader locktable slot. */

public static final class BadReaderLockException extends LmdbNativeException {

static final int MDB_BAD_RSLOT = -30_783;

private static final long serialVersionUID = 1L;

BadReaderLockException() {

super(MDB_BAD_RSLOT, "Invalid reuse of reader locktable slot");

}

/** The proposed R-W transaction is incompatible with a R-O Env. */

public static class EnvIsReadOnly extends LmdbException {

private static final long serialVersionUID = 1L;

/** Creates a new instance. */

public EnvIsReadOnly() {

super("Read-write Txn incompatible with read-only Env");

}

/** The proposed transaction is incompatible with its parent transaction. */

public static class IncompatibleParent extends LmdbException {

private static final long serialVersionUID = 1L;

/** Creates a new instance. */

public IncompatibleParent() {

super("Transaction incompatible with its parent transaction");

}

/** Transaction is not in a READY state. */

public static final class NotReadyException extends LmdbException {

private static final long serialVersionUID = 1L;

/** Creates a new instance. */

public NotReadyException() {

super("Transaction is not in ready state");

}

/** The current transaction has not been reset. */

public static class NotResetException extends LmdbException {

private static final long serialVersionUID = 1L;

/** Creates a new instance. */

public NotResetException() {

super("Transaction has not been reset");

}

/** The current transaction is not a read-only transaction. */

public static class ReadOnlyRequiredException extends LmdbException {

private static final long serialVersionUID = 1L;

/** Creates a new instance. */

public ReadOnlyRequiredException() {

super("Not a read-only transaction");

}

/** The current transaction is not a read-write transaction. */

public static class ReadWriteRequiredException extends LmdbException {

private static final long serialVersionUID = 1L;

/** Creates a new instance. */

public ReadWriteRequiredException() {

super("Not a read-write transaction");

}

/** The current transaction has already been reset. */

public static class ResetException extends LmdbException {

private static final long serialVersionUID = 1L;

/** Creates a new instance. */

public ResetException() {

super("Transaction has already been reset");

}

/** Transaction has too many dirty pages. */

public static final class TxFullException extends LmdbNativeException {

static final int MDB_TXN_FULL = -30_788;

private static final long serialVersionUID = 1L;

TxFullException() {

super(MDB_TXN_FULL, "Transaction has too many dirty pages");

}

/** Transaction states. */

enum State {

READY,

DONE,

RESET,

RELEASED

}

lmdbjava/src/main/java/org/lmdbjava/Txn.java at gh-267 · lmdbjava/lmdbjava · GitHub

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