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rxjava2-backport developed by David Karnok
/**
* Copyright 2015 David Karnok and Netflix, Inc.
*
* 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 hu.akarnokd.rxjava2.internal.util;
import java.util.concurrent.atomic.*;
import hu.akarnokd.rxjava2.functions.*;
/**
* Helper class to handle copy-on-write arrays plus terminal state for arbitrary references.
*/
public enum TerminalAtomicsHelper {
;
/**
* Atomically swaps in the terminalValue and calls the given callback if not already terminated.
* @param the instance type
* @param the reference type
* @param updater
* @param instance
* @param terminalValue
* @param onTerminate
*/
public static void terminate(AtomicReferenceFieldUpdater updater,
T instance, U terminalValue, Consumer onTerminate) {
U a = updater.get(instance);
if (a != terminalValue) {
a = updater.getAndSet(instance, terminalValue);
if (a != terminalValue && a != null) {
onTerminate.accept(a);
}
}
}
/**
* Atomically swaps in the terminalValue and calls the given callback if not already terminated.
* @param the reference type
* @param instance
* @param terminalValue
* @param onTerminate
*/
public static void terminate(AtomicReference instance,
U terminalValue, Consumer onTerminate) {
U a = instance.get();
if (a != terminalValue) {
a = instance.getAndSet(terminalValue);
if (a != terminalValue && a != null) {
onTerminate.accept(a);
}
}
}
/**
* Atomically swaps in the terminal value and returns the previous value.
* @param the instance type
* @param the reference type
* @param updater
* @param instance
* @param terminalValue
* @return the last value or the terminal value
*/
public static U terminate(AtomicReferenceFieldUpdater updater,
T instance, U terminalValue) {
U a = updater.get(instance);
if (a != terminalValue) {
a = updater.getAndSet(instance, terminalValue);
}
return a;
}
/**
* Atomically swaps in the terminal value and returns the previous value.
* @param the reference type
* @param instance
* @param terminalValue
* @return the last value or the terminal value
*/
public static U terminate(AtomicReference instance,
U terminalValue) {
U a = instance.get();
if (a != terminalValue) {
a = instance.getAndSet(terminalValue);
}
return a;
}
/**
* Atomically replaces the contents of the instance and calls the callback with the old value
* or calls the callback with the new value if the instance holds the terminal value.
* @param the instance type
* @param the reference type
* @param updater
* @param instance
* @param newValue
* @param terminalValue
* @param onTerminate
* @return false if the instance holds the terminal value
* @see #update(AtomicReferenceFieldUpdater, Object, Object, Object, Consumer)
*/
public static boolean set(AtomicReferenceFieldUpdater updater, T instance,
U newValue, U terminalValue, Consumer onTerminate) {
for (;;) {
U a = updater.get(instance);
if (a == terminalValue) {
if (newValue != null) {
onTerminate.accept(newValue);
}
return false;
}
if (updater.compareAndSet(instance, a, newValue)) {
if (a != null) {
onTerminate.accept(a);
}
return true;
}
}
}
/**
* Atomically replaces the contents of the instance and calls the callback with the old value
* or calls the callback with the new value if the instance holds the terminal value.
* @param the instance type
* @param the reference type
* @param instance
* @param newValue
* @param terminalValue
* @param onTerminate
* @return false if the instance holds the terminal value
* @see #update(AtomicReference, Object, Object, Consumer)
*/
public static boolean set(AtomicReference instance,
U newValue, U terminalValue, Consumer onTerminate) {
for (;;) {
U a = instance.get();
if (a == terminalValue) {
if (newValue != null) {
onTerminate.accept(newValue);
}
return false;
}
if (instance.compareAndSet(a, newValue)) {
if (a != null) {
onTerminate.accept(a);
}
return true;
}
}
}
/**
* Atomically replaces the content of the instance but calls the callback only if the instance holds
* the terminal value.
* @param the instance type
* @param the reference type
* @param updater
* @param instance
* @param newValue
* @param terminalValue
* @param onTerminate
* @return false if the instance holds the terminal value
* @see #set(AtomicReferenceFieldUpdater, Object, Object, Object, Consumer)
*/
public static boolean update(AtomicReferenceFieldUpdater updater, T instance,
U newValue, U terminalValue, Consumer onTerminate) {
for (;;) {
U a = updater.get(instance);
if (a == terminalValue) {
if (newValue != null) {
onTerminate.accept(newValue);
}
return false;
}
if (updater.compareAndSet(instance, a, newValue)) {
return true;
}
}
}
/**
* Atomically replaces the content of the instance but calls the callback only if the instance holds
* the terminal value.
* @param the instance type
* @param the reference type
* @param instance
* @param newValue
* @param terminalValue
* @param onTerminate
* @return false if the instance holds the terminal value
* @see #set(AtomicReference, Object, Object, Consumer)
*/
public static boolean update(AtomicReference instance,
U newValue, U terminalValue, Consumer onTerminate) {
for (;;) {
U a = instance.get();
if (a == terminalValue) {
if (newValue != null) {
onTerminate.accept(newValue);
}
return false;
}
if (instance.compareAndSet(a, newValue)) {
return true;
}
}
}
/**
* Atomically replaces the array in instance with a new array that contains the newValue as well
* or returns false if the instance holds the terminalValue.
* @param the instance type
* @param the reference type
* @param updater
* @param instance
* @param newValue
* @param terminalValue
* @param arraySupplier
* @return true if the add succeeded, false if the instance has terminated
*/
public static boolean add(AtomicReferenceFieldUpdater updater, T instance,
U newValue, U[] terminalValue, IntFunction arraySupplier) {
for (;;) {
U[] a = updater.get(instance);
if (a == terminalValue) {
return false;
}
int n = a.length;
U[] b = arraySupplier.apply(n + 1);
System.arraycopy(a, 0, b, 0, n);
b[n] = newValue;
if (updater.compareAndSet(instance, a, b)) {
return true;
}
}
}
/**
* Atomically replaces the array in instance with a new array that contains the newValue as well
* or returns false if the instance holds the terminalValue.
* @param the reference type
* @param instance
* @param newValue
* @param terminalValue
* @param arraySupplier
* @return true if the add succeeded, false if the instance has terminated
*/
public static boolean add(AtomicReference instance,
U newValue, U[] terminalValue, IntFunction arraySupplier) {
for (;;) {
U[] a = instance.get();
if (a == terminalValue) {
return false;
}
int n = a.length;
U[] b = arraySupplier.apply(n + 1);
System.arraycopy(a, 0, b, 0, n);
b[n] = newValue;
if (instance.compareAndSet(a, b)) {
return true;
}
}
}
/**
* Atomically replaces the array in instance with a new array that doesn't contain the
* given value or returns false if the instance holds the terminal state or an empty array
* or the value is not in the array.
* @param the instance type
* @param the reference type
* @param updater
* @param instance
* @param value
* @param terminalValue
* @param zeroArray
* @param arraySupplier
* @return true if the remove succeeded, false if the instance has terminated
*/
public static boolean remove(AtomicReferenceFieldUpdater updater, T instance,
U value, U[] terminalValue, U[] zeroArray, IntFunction arraySupplier) {
for (;;) {
U[] a = updater.get(instance);
if (a == terminalValue) {
return false;
}
int n = a.length;
if (n == 0) {
return false;
}
int j = -1;
for (int i = 0; i < n; i++) {
if (a[i] == value) {
j = i;
break;
}
}
if (j < 0) {
return false;
}
U[] b;
if (n == 1) {
b = zeroArray;
} else {
b = arraySupplier.apply(n - 1);
System.arraycopy(a, 0, b, 0, j);
System.arraycopy(a, j + 1, b, j, n - j - 1);
}
if (updater.compareAndSet(instance, a, b)) {
return true;
}
}
}
/**
* Atomically replaces the array in instance with a new array that doesn't contain the
* given value or returns false if the instance holds the terminal state or an empty array
* or the value is not in the array.
* @param the reference type
* @param reference
* @param value
* @param terminalValue
* @param zeroArray
* @param arraySupplier
* @return true if the remove succeeded, false if the instance has terminated
*/
public static boolean remove(AtomicReference reference,
U value, U[] terminalValue, U[] zeroArray, IntFunction arraySupplier) {
for (;;) {
U[] a = reference.get();
if (a == terminalValue) {
return false;
}
int n = a.length;
if (n == 0) {
return false;
}
int j = -1;
for (int i = 0; i < n; i++) {
if (a[i] == value) {
j = i;
break;
}
}
if (j < 0) {
return false;
}
U[] b;
if (n == 1) {
b = zeroArray;
} else {
b = arraySupplier.apply(n - 1);
System.arraycopy(a, 0, b, 0, j);
System.arraycopy(a, j + 1, b, j, n - j - 1);
}
if (reference.compareAndSet(a, b)) {
return true;
}
}
}
}
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