org.sputnikdev.bluetooth.manager.impl.AbstractBluetoothObjectGovernor Maven / Gradle / Ivy
package org.sputnikdev.bluetooth.manager.impl;
/*-
* #%L
* org.sputnikdev:bluetooth-manager
* %%
* Copyright (C) 2017 Sputnik Dev
* %%
* 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%
*/
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.sputnikdev.bluetooth.URL;
import org.sputnikdev.bluetooth.manager.BluetoothGovernor;
import org.sputnikdev.bluetooth.manager.BluetoothInteractionException;
import org.sputnikdev.bluetooth.manager.GovernorListener;
import org.sputnikdev.bluetooth.manager.GovernorState;
import org.sputnikdev.bluetooth.manager.NotReadyException;
import org.sputnikdev.bluetooth.manager.transport.BluetoothObject;
import java.time.Instant;
import java.util.List;
import java.util.Objects;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.CopyOnWriteArrayList;
import java.util.concurrent.locks.ReentrantLock;
import java.util.function.BiConsumer;
import java.util.function.Consumer;
import java.util.function.Function;
/**
* A root class for all governors in the system. Defines lifecycle and error handling/recovery processes for governors.
*
* The lifecycle is divided on the following stages:
*
*
* - Native object acquisition
* - Error handling and recovery
* - Governing/maintaining state of the bluetooth object
*
*
* All the stages above are handled in {@link #update()} method. When invoked, this method tries to acquire
* a native object for corresponding device first. When acquired, {@link #init(BluetoothObject)} method is called
* to perform initialisation (setting initial state, subscribing to the object events), then all registered governor
* listeners are notified that the governor is "ready" by triggering {@link GovernorListener#ready(boolean)} method.
* Once initialised, the {@link #update()} method switches to the next stage - maintaining state of the bluetooth
* object by invoking {@link #update(BluetoothObject)} method, this is where main manipulations with
* the bluetooth object are happening. If any exception occurs in the {@link #update(BluetoothObject)} method,
* the Error handling stage begins by triggering {@link #reset(BluetoothObject)} method, which must revert
* internal state of the governor to the initial state - the Native object acquisition.
*
*
In short this looks like that:
*
*
The update method is called outside of the governor (by a separate thread):
* governor.update();
*
*
then the following happens:
*
* {@link #init(BluetoothObject)}
* {@link GovernorListener#ready(boolean)} with argument - true
* {@link #update(BluetoothObject)}
*
*
if the {@link #update(BluetoothObject)} method throws any exception, then
* {@link #reset(BluetoothObject)}
* {@link GovernorListener#ready(boolean)} with argument - false
* are invoked, which brings the governor to its initial state, where everything begins from the start.
*
*
In order to help to release resources (native objects) {@link #reset(BluetoothObject)} method is used,
* which must release any acquired resources, disconnect and unsubscribe from notifications.
* It is recommended to call this method when, for example, a program exists or in any similar cases.
*
* @author Vlad Kolotov
*/
abstract class AbstractBluetoothObjectGovernor implements BluetoothObjectGovernor {
private Logger logger = LoggerFactory.getLogger(AbstractBluetoothObjectGovernor.class);
protected final BluetoothManagerImpl bluetoothManager;
protected final URL url;
private T bluetoothObject;
private String transport;
private Instant lastInteracted;
private Instant lastChangedNotified;
private Instant ready;
private final List governorListeners = new CopyOnWriteArrayList<>();
private GovernorState state = GovernorState.NEW;
@SuppressWarnings({"unchecked", "rawtypes"})
private final CompletableFutureService readyService =
new CompletableFutureService<>(this, BluetoothGovernor::isReady);
private final ReentrantLock updateLock = new ReentrantLock();
AbstractBluetoothObjectGovernor(BluetoothManagerImpl bluetoothManager, URL url) {
this.bluetoothManager = bluetoothManager;
this.url = url;
}
@Override
public URL getURL() {
return url;
}
@Override
public boolean isReady() {
return bluetoothObject != null;
}
@Override
public void addGovernorListener(GovernorListener listener) {
governorListeners.add(listener);
}
@Override
public void removeGovernorListener(GovernorListener listener) {
governorListeners.remove(listener);
}
@Override
public Instant getLastInteracted() {
return lastInteracted;
}
@Override
public boolean equals(Object o) {
if (this == o) {
return true;
}
if (!(o instanceof AbstractBluetoothObjectGovernor)) {
return false;
}
AbstractBluetoothObjectGovernor that = (AbstractBluetoothObjectGovernor) o;
return Objects.equals(url, that.url);
}
@Override
public int hashCode() {
return Objects.hash(url);
}
public String getTransport() {
return transport;
}
@Override
public void init() {
update();
}
@Override
public void update() {
if (state != GovernorState.DISPOSED) {
logger.debug("Updating governor. Trying to acquire lock: {}", url);
boolean updated = false;
T object = null;
if (updateLock.tryLock()) {
try {
logger.trace("Lock acquired. Getting a native object: {}", url);
object = getOrFindBluetoothObject();
if (object == null) {
logger.trace("Native object is not available: {}", url);
return;
}
logger.trace("Performing update with the native object: {} / {}",
url, Integer.toHexString(object.hashCode()));
update(object);
logger.debug("Governor has been updated: {}", url);
updated = true;
// handling completable futures
bluetoothManager.notify(readyService::complete);
} catch (Exception ex) {
logger.warn("Error occurred while updating governor: {} / {} : {}",
url, object != null ? Integer.toHexString(object.hashCode()) : null, ex.getMessage());
reset();
} finally {
logger.trace("Unlocking update (update) lock: {}", url);
updateLock.unlock();
}
if (updated) {
notifyLastChanged();
}
}
}
}
public void reset() {
if (state != GovernorState.RESET && state != GovernorState.DISPOSED) {
state = GovernorState.RESET;
if (!url.isCharacteristic()) {
logger.debug("Resetting governor. Descendants first: {}", url);
bluetoothManager.resetDescendants(url);
}
try {
if (bluetoothObject != null) {
forceReset(bluetoothObject);
}
bluetoothObject = null;
logger.debug("Governor has been reset: {}", url);
} catch (Exception ex) {
logger.debug("Error occurred while resetting governor {}: {}", url, ex.getMessage());
}
}
}
@Override
public void dispose() {
if (state != GovernorState.DISPOSED) {
logger.debug("Disposing governor: {}", url);
reset();
state = GovernorState.DISPOSED;
governorListeners.clear();
readyService.clear();
}
}
@Override
@SuppressWarnings({"unchecked", "rawtypes"})
public CompletableFuture whenReady(Function function) {
return readyService.submit((Function) function);
}
protected void scheduleUpdate() {
bluetoothManager.scheduleUpdate(this);
}
protected R interact(String name, Function delegate) {
return interact(name, delegate, false);
}
protected R interact(String name, Function delegate, boolean update) {
try {
T object = getBluetoothObject();
logger.trace("Interacting with native object ({}): {} / {}",
name, url, Integer.toHexString(object.hashCode()));
R result = delegate.apply(object);
logger.trace("Interaction completed ({}): {} / {}", name, url, Integer.toHexString(object.hashCode()));
if (update) {
updateLastInteracted();
}
return result;
} catch (Exception ex) {
boolean locked = updateLock.isLocked();
String message = String.format("Error occurred while interacting (%s) with native object: %s : %s : %s",
name, url, locked, ex.getMessage());
logger.warn(message);
// no need to reset if it is locked in the update or reset method
//TODO decide if it is needed
//if (!locked) {
reset();
//}
throw new BluetoothInteractionException(message, ex);
}
}
protected void interact(String name, BiConsumer delegate, V value) {
interact(name, (Function) object -> {
delegate.accept(object, value);
return null;
}, true);
}
protected void interact(String name, Consumer delegate) {
interact(name, (Function) object -> {
delegate.accept(object);
return null;
});
}
private T getBluetoothObject() throws NotReadyException {
logger.trace("Getting native object. Checking if governor is ready: {}", url);
if (!isReady()) {
logger.trace("Governor is not ready. Trying to perform an explicit update: {}", url);
// the governor is not ready, trying to update it
update();
logger.trace("Checking if governor is ready after the explicit update: {}", url);
if (!isReady()) {
// still not ready even after the update?
throw new NotReadyException("Bluetooth object is not ready: " + url);
}
}
logger.trace("Returning native object: {} / {}", url,
bluetoothObject != null ? Integer.toHexString(bluetoothObject.hashCode()) : null);
return bluetoothObject;
}
abstract void init(T object);
abstract void update(T object);
abstract void reset(T object);
void updateLastInteracted() {
lastInteracted = Instant.now();
}
void notifyReady(boolean ready) {
bluetoothManager.notify(() -> {
BluetoothManagerUtils.forEachSilently(governorListeners, GovernorListener::ready, ready, logger,
"Execution error of a governor listener: ready");
bluetoothManager.notifyGovernorReady(this, ready);
});
}
void notifyLastChanged() {
notifyLastChanged(lastInteracted);
}
void notifyLastChanged(Instant time) {
if (time != null && !time.equals(lastChangedNotified)) {
bluetoothManager.notify(governorListeners, GovernorListener::lastUpdatedChanged, time, logger,
"Execution error of a governor listener: last changed");
lastChangedNotified = time;
}
}
Instant getReady() {
return ready;
}
private T getOrFindBluetoothObject() {
logger.trace("Acquiring native object: {}", url);
if (bluetoothObject == null) {
logger.trace("Native object is null. Trying to get a new native object from manager: {}", url);
bluetoothObject = bluetoothManager.getBluetoothObject(
transport != null ? url.copyWithProtocol(transport) : url);
if (bluetoothObject != null) {
ready = Instant.now();
logger.debug("A new native object has been acquired: {}", url);
// update internal cache so that next time acquiring "native" object will be faster
transport = bluetoothObject.getURL().getProtocol();
try {
logger.debug("Initializing governor with the new native object: {}", url);
init(bluetoothObject);
logger.trace("Initialization succeeded: {}", url);
state = GovernorState.READY;
notifyReady(true);
} catch (Exception ex) {
logger.warn("Error occurred while initializing governor with a new native object: {} : {}",
url, ex.getMessage());
throw ex;
}
}
}
logger.trace("Returning native object: {}", url);
return bluetoothObject;
}
private void forceReset(T bluetoothObject) {
try {
logger.trace("Resetting native object: {} / {}", url, Integer.toHexString(bluetoothObject.hashCode()));
reset(bluetoothObject);
} catch (Exception ex) {
logger.trace("Could not reset bluetooth object {}: {}", url, ex.getMessage());
}
notifyReady(false);
try {
logger.trace("Disposing native object: {} / {}", url, Integer.toHexString(bluetoothObject.hashCode()));
bluetoothManager.disposeBluetoothObject(bluetoothObject.getURL());
} catch (Exception ex) {
logger.trace("Could not dispose bluetooth object {}: {}", url, ex.getMessage());
}
}
}