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/*
* Copyright (c) 2016-2022 chronicle.software
*
* https://chronicle.software
*
* 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 net.openhft.chronicle.bytes.ref;
import net.openhft.chronicle.bytes.Bytes;
import net.openhft.chronicle.bytes.BytesStore;
import net.openhft.chronicle.bytes.BytesUtil;
import net.openhft.chronicle.core.Jvm;
import net.openhft.chronicle.core.annotation.NonNegative;
import net.openhft.chronicle.core.io.ClosedIllegalStateException;
import net.openhft.chronicle.core.io.ThreadingIllegalStateException;
import net.openhft.chronicle.core.util.ThrowingLongSupplier;
import org.jetbrains.annotations.NotNull;
import java.nio.BufferOverflowException;
import static java.nio.charset.StandardCharsets.ISO_8859_1;
import static net.openhft.chronicle.bytes.BytesUtil.roundUpTo8ByteAlign;
/**
* Implementation of a reference to an array of 64-bit long values in Text wire format.
* The text representation includes an atomic lock flag along with the value.
* The format is: {@code !!atomic { locked: false, value: 00000000000000000000 } }.
*/
@SuppressWarnings("rawtypes")
public class TextLongReference extends AbstractReference implements LongReference {
static final int VALUE = 34;
private static final byte[] template = "!!atomic { locked: false, value: 00000000000000000000 }".getBytes(ISO_8859_1);
private static final int FALSE = BytesUtil.asInt("fals");
private static final int TRUE = BytesUtil.asInt(" tru");
private static final long UNINITIALIZED = 0x0L;
private static final long LONG_TRUE = 1L;
private static final long LONG_FALSE = 0L;
private static final int LOCKED = 20;
private static final int DIGITS = 20;
/**
* Writes the initial structure of a 64-bit long value to the specified {@link Bytes} instance
* in Text wire format, with the given value.
*
* @param bytes the Bytes instance to write to.
* @param value the long value to be written.
* @throws BufferOverflowException If there's not enough space in the buffer to write the value.
* @throws IllegalArgumentException If an illegal argument is provided.
* @throws ClosedIllegalStateException If the resource has been released or closed.
* @throws ThreadingIllegalStateException If this resource was accessed by multiple threads in an unsafe way
*/
public static void write(@NotNull Bytes bytes, @NonNegative long value)
throws BufferOverflowException, IllegalArgumentException, IllegalStateException {
long position = bytes.writePosition();
bytes.write(template);
bytes.append(position + VALUE, value, DIGITS);
}
/**
* Executes the given {@link ThrowingLongSupplier} within a lock to ensure thread safety.
*
* @param call the ThrowingLongSupplier to be executed.
* @return the result of ThrowingLongSupplier.
* @throws ClosedIllegalStateException If the resource has been released or closed.
* @throws ThreadingIllegalStateException If this resource was accessed by multiple threads in an unsafe way
*/
private long withLock(@NotNull ThrowingLongSupplier call)
throws IllegalStateException {
try {
long valueOffset = offset + LOCKED;
int value = bytesStore.readVolatileInt(valueOffset);
if (value != FALSE && value != TRUE)
throw new IllegalStateException("Not a lock value");
while (true) {
if (bytesStore.compareAndSwapInt(valueOffset, FALSE, TRUE)) {
long t = call.getAsLong();
bytesStore.writeOrderedInt(valueOffset, FALSE);
return t;
}
}
} catch (NullPointerException e) {
throwExceptionIfClosed();
throw e;
} catch (Exception e) {
throw Jvm.rethrow(e);
}
}
/**
* Configures the byte store for this reference.
*
* @param bytes the BytesStore instance where the reference is to be stored.
* @param offset the offset in the byte store where the reference is to be positioned.
* @param length the length of the reference in bytes.
* @throws IllegalArgumentException If an illegal argument is provided.
* @throws BufferOverflowException If there's not enough space in the buffer to write the reference.
* @throws ClosedIllegalStateException If the resource has been released or closed.
* @throws ThreadingIllegalStateException If this resource was accessed by multiple threads in an unsafe way
*/
@SuppressWarnings("rawtypes")
@Override
public void bytesStore(final @NotNull BytesStore bytes, @NonNegative long offset, @NonNegative long length)
throws IllegalArgumentException, IllegalStateException, BufferOverflowException {
if (length != template.length)
throw new IllegalArgumentException();
// align for ARM
long newOffset = roundUpTo8ByteAlign(offset);
for (long i = offset; i < newOffset; i++) {
bytes.writeByte(i, (byte) ' ');
}
super.bytesStore(bytes, newOffset, length);
if (bytes.readLong(newOffset) == UNINITIALIZED)
bytes.write(newOffset, template);
}
/**
* Retrieves the value from the Text wire format.
*
* @return the long value.
* @throws ClosedIllegalStateException If the resource has been released or closed.
* @throws ThreadingIllegalStateException If this resource was accessed by multiple threads in an unsafe way
*/
@Override
public long getValue()
throws IllegalStateException {
return withLock(() -> bytesStore.parseLong(offset + VALUE));
}
/**
* Sets the value in the Text wire format.
*
* @param value the value to be set.
* @throws ClosedIllegalStateException If the resource has been released or closed.
* @throws ThreadingIllegalStateException If this resource was accessed by multiple threads in an unsafe way
*/
@Override
public void setValue(long value)
throws IllegalStateException {
withLock(() -> {
bytesStore.append(offset + VALUE, value, DIGITS);
return LONG_TRUE;
});
}
@Override
public long maxSize() {
return template.length;
}
@NotNull
@Override
public String toString() {
try {
return "value: " + getValue();
} catch (Exception e) {
return e.toString();
}
}
@Override
public long addValue(long delta)
throws IllegalStateException {
return withLock(() -> {
long value = bytesStore.parseLong(offset + VALUE) + delta;
bytesStore.append(offset + VALUE, value, DIGITS);
return value;
});
}
/**
* Atomically sets the value to the given updated value if the current value is
* equal to the expected value.
*
* @param expected the expected value.
* @param value the new value.
* @return {@code true} if successful, {@code false} otherwise.
* @throws ClosedIllegalStateException If the resource has been released or closed.
* @throws ThreadingIllegalStateException If this resource was accessed by multiple threads in an unsafe way
*/
@Override
public boolean compareAndSwapValue(long expected, long value)
throws IllegalStateException {
return withLock(() -> {
if (bytesStore.parseLong(offset + VALUE) == expected) {
bytesStore.append(offset + VALUE, value, DIGITS);
return LONG_TRUE;
}
return LONG_FALSE;
}) == LONG_TRUE;
}
}
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