net.openhft.chronicle.bytes.ref.TextIntReference Maven / Gradle / Ivy
/*
* 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.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.ThrowingIntSupplier;
import net.openhft.chronicle.core.values.IntValue;
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;
/**
* TextIntReference is an implementation of a reference to a 32-bit integer, represented
* in text wire format. It extends AbstractReference and implements IntValue. The text representation
* is formatted to resemble a JSON-like content for an atomic 32-bit integer with a lock indicator.
*
* The format of the text representation is:
* {@code !!atomic { locked: false, value: 0000000000 }}
*
*/
@SuppressWarnings("rawtypes")
public class TextIntReference extends AbstractReference implements IntValue {
private static final byte[] template = "!!atomic { locked: false, value: 0000000000 }".getBytes(ISO_8859_1);
private static final int FALSE = 'f' | ('a' << 8) | ('l' << 16) | ('s' << 24);
private static final int TRUE = ' ' | ('t' << 8) | ('r' << 16) | ('u' << 24);
private static final int UNINITIALIZED = 0;
private static final int INT_TRUE = 1;
private static final int INT_FALSE = 0;
private static final int LOCKED = 20;
private static final int VALUE = 34;
private static final int DIGITS = 10;
/**
* Writes the provided 32-bit integer value into the given Bytes instance in Text wire format.
*
* @param bytes the Bytes instance to write to.
* @param value the 32-bit integer value to be written.
* @throws BufferOverflowException If there is insufficient space.
* @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 int value)
throws BufferOverflowException, IllegalStateException {
long position = bytes.writePosition();
bytes.write(template);
bytes.append(position + VALUE, value, DIGITS);
}
/**
* Executes a callable function with lock to ensure atomicity and consistency.
*
* @param call the callable function to execute with lock.
* @return the integer value returned by the callable function.
* @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 int withLock(@NotNull ThrowingIntSupplier call)
throws IllegalStateException {
try {
long alignedOffset = roundUpTo8ByteAlign(offset);
long lockValueOffset = alignedOffset + LOCKED;
int lockValue = bytesStore.readVolatileInt(lockValueOffset);
if (lockValue != FALSE && lockValue != TRUE)
throw new IllegalStateException("lockValue: " + lockValue);
while (true) {
if (bytesStore.compareAndSwapInt(lockValueOffset, FALSE, TRUE)) {
int t = call.getAsInt();
bytesStore.writeOrderedInt(lockValueOffset, FALSE);
return t;
}
}
} catch (Exception e) {
throw Jvm.rethrow(e);
}
}
/**
* Retrieves the 32-bit integer value from the Text wire format.
*
* @return the 32-bit integer 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 int getValue()
throws IllegalStateException {
throwExceptionIfClosed();
return withLock(() -> (int) bytesStore.parseLong(offset + VALUE));
}
/**
* Sets the 32-bit integer value in the Text wire format.
*
* @param value the 32-bit integer 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(int value)
throws IllegalStateException {
throwExceptionIfClosedInSetter();
withLock(() -> {
bytesStore.append(offset + VALUE, value, DIGITS);
return INT_TRUE;
});
}
@Override
public int getVolatileValue()
throws IllegalStateException {
throwExceptionIfClosed();
return getValue();
}
@Override
public void setOrderedValue(int value)
throws IllegalStateException {
throwExceptionIfClosedInSetter();
setValue(value);
}
@Override
public int addValue(int delta)
throws IllegalStateException {
throwExceptionIfClosed();
return withLock(() -> {
long value = bytesStore.parseLong(offset + VALUE) + delta;
bytesStore.append(offset + VALUE, value, DIGITS);
return (int) value;
});
}
@Override
public int addAtomicValue(int delta)
throws IllegalStateException {
throwExceptionIfClosed();
return addValue(delta);
}
@Override
public boolean compareAndSwapValue(int expected, int value)
throws IllegalStateException {
throwExceptionIfClosed();
return withLock(() -> {
if (bytesStore.parseLong(offset + VALUE) == expected) {
bytesStore.append(offset + VALUE, value, DIGITS);
return INT_TRUE;
}
return INT_FALSE;
}) == INT_TRUE;
}
@SuppressWarnings("rawtypes")
@Override
public void bytesStore(final @NotNull BytesStore bytes, @NonNegative long offset, @NonNegative long length)
throws IllegalStateException, IllegalArgumentException, BufferOverflowException {
throwExceptionIfClosedInSetter();
if (length != template.length)
throw new IllegalArgumentException(length + " != " + template.length);
// 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.readInt(newOffset) == UNINITIALIZED)
bytes.write(newOffset, template);
}
@Override
public long maxSize() {
return template.length;
}
/**
* Returns the string representation of the TextIntReference.
*
* @return a string representing the value contained in the TextIntReference.
*/
@NotNull
@Override
public String toString() {
try {
return "value: " + getValue();
} catch (Exception e) {
return e.toString();
}
}
}