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Caching for CUPS status performance (#6)
Caching for CUPS status performance --------- Co-authored-by: Vzor- <Kyle@Berezin.com>
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,96 @@ | ||
| package qz.common; | ||
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| import java.util.concurrent.TimeUnit; | ||
| import java.util.concurrent.atomic.AtomicInteger; | ||
| import java.util.function.Supplier; | ||
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| /** | ||
| * A generic class that encapsulates an object for caching. The cached object | ||
| * will be refreshed automatically when accessed after its lifespan has expired. | ||
| * | ||
| * @param <T> The type of object to be cached. | ||
| */ | ||
| public class CachedObject<T> { | ||
| public static final long DEFAULT_LIFESPAN = 5000; // in milliseconds | ||
| T lastObject; | ||
| Supplier<T> supplier; | ||
| private long timestamp; | ||
| private long lifespan; | ||
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| /** | ||
| * Creates a new CachedObject with a default lifespan of 5000 milliseconds | ||
| * | ||
| * @param supplier The function to pull new values from | ||
| */ | ||
| public CachedObject(Supplier<T> supplier) { | ||
| this(supplier, DEFAULT_LIFESPAN); | ||
| } | ||
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| /** | ||
| * Creates a new CachedObject | ||
| * | ||
| * @param supplier The function to pull new values from | ||
| * @param lifespan The lifespan of the cached object in milliseconds | ||
| */ | ||
| public CachedObject(Supplier<T> supplier, long lifespan) { | ||
| this.supplier = supplier; | ||
| setLifespan(lifespan); | ||
| timestamp = Long.MIN_VALUE; // System.nanoTime() can be negative, MIN_VALUE guarantees a first-run. | ||
| } | ||
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| /** | ||
| * Registers a new supplier for the CachedObject | ||
| * | ||
| * @param supplier The function to pull new values from | ||
| */ | ||
| public void registerSupplier(Supplier<T> supplier) { | ||
| this.supplier = supplier; | ||
| } | ||
|
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| /** | ||
| * Sets the lifespan of the cached object | ||
| * | ||
| * @param milliseconds The lifespan of the cached object in milliseconds | ||
| */ | ||
| public void setLifespan(long milliseconds) { | ||
| lifespan = Math.max(0, milliseconds); // prevent overflow | ||
| } | ||
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| /** | ||
| * Retrieves the cached object. | ||
| * If the cached object's lifespan has expired, it gets refreshed before being returned. | ||
| * | ||
| * @return The cached object | ||
| */ | ||
| public T get() { | ||
| return get(false); | ||
| } | ||
|
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| /** | ||
| * Retrieves the cached object. | ||
| * If the cached object's lifespan is expired or forceRefresh is true, it gets refreshed before being returned. | ||
| * | ||
| * @param forceRefresh If true, the cached object will be refreshed before being returned regardless of its lifespan | ||
| * @return The cached object | ||
| */ | ||
| public T get(boolean forceRefresh) { | ||
| long now = TimeUnit.NANOSECONDS.toMillis(System.nanoTime()); | ||
| // check lifespan | ||
| if (forceRefresh || (timestamp + lifespan <= now)) { | ||
| timestamp = now; | ||
| lastObject = supplier.get(); | ||
| } | ||
| return lastObject; | ||
| } | ||
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| // Test | ||
| public static void main(String ... args) throws InterruptedException { | ||
| final AtomicInteger testInt = new AtomicInteger(0); | ||
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| CachedObject<Integer> cachedString = new CachedObject<>(testInt::incrementAndGet); | ||
| for(int i = 0; i < 100; i++) { | ||
| Thread.sleep(1500); | ||
| System.out.println(cachedString.get()); | ||
| } | ||
| } | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,130 @@ | ||
| package qz.printer.info; | ||
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| import qz.common.CachedObject; | ||
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| import javax.print.*; | ||
| import javax.print.attribute.Attribute; | ||
| import javax.print.attribute.AttributeSet; | ||
| import javax.print.attribute.PrintServiceAttribute; | ||
| import javax.print.attribute.PrintServiceAttributeSet; | ||
| import javax.print.event.PrintServiceAttributeListener; | ||
| import java.util.HashMap; | ||
| import java.util.function.Supplier; | ||
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| public class CachedPrintService implements PrintService { | ||
| public PrintService innerPrintService; | ||
| // PrintService.getName() is slow, use a cache instead per JDK-7001133 | ||
| // TODO: Remove this comment when upstream bug report is filed | ||
| private static final long lifespan = CachedObject.DEFAULT_LIFESPAN; | ||
| private static final CachedObject<PrintService> cachedDefault = new CachedObject<>(CachedPrintService::innerLookupDefaultPrintService, lifespan); | ||
| private static final CachedObject<PrintService[]> cachedPrintServices = new CachedObject<>(CachedPrintService::innerLookupPrintServices, lifespan); | ||
| private final CachedObject<String> cachedName; | ||
| private final CachedObject<PrintServiceAttributeSet> cachedAttributeSet; | ||
| private final HashMap<Class<?>, CachedObject<?>> cachedAttributes = new HashMap<>(); | ||
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| public static PrintService lookupDefaultPrintService() { | ||
| return cachedDefault.get(); | ||
| } | ||
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| public static PrintService[] lookupPrintServices() { | ||
| return cachedPrintServices.get(); | ||
| } | ||
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| private static PrintService innerLookupDefaultPrintService() { | ||
| return new CachedPrintService(PrintServiceLookup.lookupDefaultPrintService()); | ||
| } | ||
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| private static PrintService[] innerLookupPrintServices() { | ||
| PrintService[] printServices = PrintServiceLookup.lookupPrintServices(null, null); | ||
| for (int i = 0; i < printServices.length; i++) { | ||
| printServices[i] = new CachedPrintService(printServices[i]); | ||
| } | ||
| return printServices; | ||
| } | ||
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| public CachedPrintService(PrintService printService) { | ||
| innerPrintService = printService; | ||
| cachedName = new CachedObject<>(innerPrintService::getName, lifespan); | ||
| cachedAttributeSet = new CachedObject<>(innerPrintService::getAttributes, lifespan); | ||
| } | ||
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| @Override | ||
| public String getName() { | ||
| return cachedName.get(); | ||
| } | ||
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| @Override | ||
| public DocPrintJob createPrintJob() { | ||
| return innerPrintService.createPrintJob(); | ||
| } | ||
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| @Override | ||
| public void addPrintServiceAttributeListener(PrintServiceAttributeListener listener) { | ||
| innerPrintService.addPrintServiceAttributeListener(listener); | ||
| } | ||
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| @Override | ||
| public void removePrintServiceAttributeListener(PrintServiceAttributeListener listener) { | ||
| innerPrintService.removePrintServiceAttributeListener(listener); | ||
| } | ||
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| @Override | ||
| public PrintServiceAttributeSet getAttributes() { | ||
| return cachedAttributeSet.get(); | ||
| } | ||
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| @Override | ||
| public <T extends PrintServiceAttribute> T getAttribute(Class<T> category) { | ||
| if (!cachedAttributes.containsKey(category)) { | ||
| Supplier<T> supplier = () -> innerPrintService.getAttribute(category); | ||
| CachedObject<T> cachedObject = new CachedObject<>(supplier, lifespan); | ||
| cachedAttributes.put(category, cachedObject); | ||
| } | ||
| return category.cast(cachedAttributes.get(category).get()); | ||
| } | ||
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| @Override | ||
| public DocFlavor[] getSupportedDocFlavors() { | ||
| return innerPrintService.getSupportedDocFlavors(); | ||
| } | ||
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| @Override | ||
| public boolean isDocFlavorSupported(DocFlavor flavor) { | ||
| return innerPrintService.isDocFlavorSupported(flavor); | ||
| } | ||
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| @Override | ||
| public Class<?>[] getSupportedAttributeCategories() { | ||
| return innerPrintService.getSupportedAttributeCategories(); | ||
| } | ||
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| @Override | ||
| public boolean isAttributeCategorySupported(Class<? extends Attribute> category) { | ||
| return innerPrintService.isAttributeCategorySupported(category); | ||
| } | ||
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| @Override | ||
| public Object getDefaultAttributeValue(Class<? extends Attribute> category) { | ||
| return innerPrintService.getDefaultAttributeValue(category); | ||
| } | ||
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| @Override | ||
| public Object getSupportedAttributeValues(Class<? extends Attribute> category, DocFlavor flavor, AttributeSet attributes) { | ||
| return innerPrintService.getSupportedAttributeValues(category, flavor, attributes); | ||
| } | ||
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| @Override | ||
| public boolean isAttributeValueSupported(Attribute attrval, DocFlavor flavor, AttributeSet attributes) { | ||
| return innerPrintService.isAttributeValueSupported(attrval, flavor, attributes); | ||
| } | ||
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| @Override | ||
| public AttributeSet getUnsupportedAttributes(DocFlavor flavor, AttributeSet attributes) { | ||
| return innerPrintService.getUnsupportedAttributes(flavor, attributes); | ||
| } | ||
|
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| @Override | ||
| public ServiceUIFactory getServiceUIFactory() { | ||
| return innerPrintService.getServiceUIFactory(); | ||
| } | ||
| } |
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