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Printer Status: Performance improvements (qzind#1124)
Caching for CUPS status performance (#6) --------- Co-authored-by: Vzor- <[email protected]>
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,97 @@ | ||
| 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 | ||
| */ | ||
| @SuppressWarnings("unused") | ||
| 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 +1,133 @@ | ||
| 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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| /** | ||
| * <code>PrintService.getName()</code> is slow, and gets increasingly slower the more times it's called. | ||
| * | ||
| * By overriding and caching the <code>PrintService</code> attributes, we're able to help suppress/delay the | ||
| * performance loss of this bug. | ||
| * | ||
| * See also JDK-7001133 | ||
| */ | ||
| public class CachedPrintService implements PrintService { | ||
| private final PrintService printService; | ||
| private final long lifespan; | ||
| private final CachedObject<String> cachedName; | ||
| private final CachedObject<PrintServiceAttributeSet> cachedAttributeSet; | ||
| private final HashMap<Class<?>, CachedObject<?>> cachedAttributes = new HashMap<>(); | ||
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| public CachedPrintService(PrintService printService, long lifespan) { | ||
| this.printService = printService; | ||
| this.lifespan = lifespan; | ||
| cachedName = new CachedObject<>(this.printService::getName, lifespan); | ||
| cachedAttributeSet = new CachedObject<>(this.printService::getAttributes, lifespan); | ||
| } | ||
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| public CachedPrintService(PrintService printService) { | ||
| this(printService, CachedObject.DEFAULT_LIFESPAN); | ||
| } | ||
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| @Override | ||
| public String getName() { | ||
| return cachedName.get(); | ||
| } | ||
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| @Override | ||
| public DocPrintJob createPrintJob() { | ||
| return printService.createPrintJob(); | ||
| } | ||
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| @Override | ||
| public void addPrintServiceAttributeListener(PrintServiceAttributeListener listener) { | ||
| printService.addPrintServiceAttributeListener(listener); | ||
| } | ||
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| @Override | ||
| public void removePrintServiceAttributeListener(PrintServiceAttributeListener listener) { | ||
| printService.removePrintServiceAttributeListener(listener); | ||
| } | ||
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| @Override | ||
| public PrintServiceAttributeSet getAttributes() { | ||
| return cachedAttributeSet.get(); | ||
| } | ||
|
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| public PrintService getJavaxPrintService() { | ||
| return printService; | ||
| } | ||
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| @Override | ||
| public <T extends PrintServiceAttribute> T getAttribute(Class<T> category) { | ||
| if (!cachedAttributes.containsKey(category)) { | ||
| Supplier<T> supplier = () -> printService.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 printService.getSupportedDocFlavors(); | ||
| } | ||
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| @Override | ||
| public boolean isDocFlavorSupported(DocFlavor flavor) { | ||
| return printService.isDocFlavorSupported(flavor); | ||
| } | ||
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| @Override | ||
| public Class<?>[] getSupportedAttributeCategories() { | ||
| return printService.getSupportedAttributeCategories(); | ||
| } | ||
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| @Override | ||
| public boolean isAttributeCategorySupported(Class<? extends Attribute> category) { | ||
| return printService.isAttributeCategorySupported(category); | ||
| } | ||
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| @Override | ||
| public Object getDefaultAttributeValue(Class<? extends Attribute> category) { | ||
| return printService.getDefaultAttributeValue(category); | ||
| } | ||
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| @Override | ||
| public Object getSupportedAttributeValues(Class<? extends Attribute> category, DocFlavor flavor, AttributeSet attributes) { | ||
| return printService.getSupportedAttributeValues(category, flavor, attributes); | ||
| } | ||
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| @Override | ||
| public boolean isAttributeValueSupported(Attribute attrval, DocFlavor flavor, AttributeSet attributes) { | ||
| return printService.isAttributeValueSupported(attrval, flavor, attributes); | ||
| } | ||
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| @Override | ||
| public AttributeSet getUnsupportedAttributes(DocFlavor flavor, AttributeSet attributes) { | ||
| return printService.getUnsupportedAttributes(flavor, attributes); | ||
| } | ||
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| @Override | ||
| public ServiceUIFactory getServiceUIFactory() { | ||
| return printService.getServiceUIFactory(); | ||
| } | ||
|
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| public boolean equals(Object obj) { | ||
| return (obj == this || | ||
| (obj instanceof PrintService && | ||
| ((PrintService)obj).getName().equals(getName()))); | ||
| } | ||
|
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| public int hashCode() { | ||
| return this.getClass().hashCode()+getName().hashCode(); | ||
| } | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,81 @@ | ||
| package qz.printer.info; | ||
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| import qz.common.CachedObject; | ||
|
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| import javax.print.PrintService; | ||
| import javax.print.PrintServiceLookup; | ||
|
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| /** | ||
| * PrintService[] cache to workaround JDK-7001133 | ||
| * | ||
| * See also <code>CachedPrintService</code> | ||
| */ | ||
| public class CachedPrintServiceLookup { | ||
| private static final CachedObject<CachedPrintService> cachedDefault = new CachedObject<>(CachedPrintServiceLookup::wrapDefaultPrintService); | ||
| private static final CachedObject<CachedPrintService[]> cachedPrintServices = new CachedObject<>(CachedPrintServiceLookup::wrapPrintServices); | ||
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| // Keep CachedPrintService object references between calls to supplier | ||
| private static CachedPrintService[] cachedPrintServicesCopy = {}; | ||
|
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| static { | ||
| setLifespan(CachedObject.DEFAULT_LIFESPAN); | ||
| } | ||
|
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| public static PrintService lookupDefaultPrintService() { | ||
| return cachedDefault.get(); | ||
| } | ||
|
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| public static void setLifespan(long lifespan) { | ||
| cachedDefault.setLifespan(lifespan); | ||
| cachedPrintServices.setLifespan(lifespan); | ||
| } | ||
|
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| public static PrintService[] lookupPrintServices() { | ||
| return cachedPrintServices.get(); | ||
| } | ||
|
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| private static CachedPrintService wrapDefaultPrintService() { | ||
| PrintService javaxPrintService = PrintServiceLookup.lookupDefaultPrintService(); | ||
| // CachedObject's supplier returns null | ||
| if(javaxPrintService == null) { | ||
| return null; | ||
| } | ||
| // If this CachedPrintService already exists, reuse it rather than wrapping a new one | ||
| CachedPrintService cachedPrintService = getMatch(cachedPrintServicesCopy, javaxPrintService); | ||
| if (cachedPrintService == null) { | ||
| // Wrap a new one | ||
| cachedPrintService = new CachedPrintService(javaxPrintService); | ||
| } | ||
| return cachedPrintService; | ||
| } | ||
|
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| private static CachedPrintService[] wrapPrintServices() { | ||
| PrintService[] javaxPrintServices = PrintServiceLookup.lookupPrintServices(null, null); | ||
| CachedPrintService[] cachedPrintServices = new CachedPrintService[javaxPrintServices.length]; | ||
| for (int i = 0; i < javaxPrintServices.length; i++) { | ||
| // If this CachedPrintService already exists, reuse it rather than wrapping a new one | ||
| cachedPrintServices[i] = getMatch(cachedPrintServicesCopy, javaxPrintServices[i]); | ||
| if (cachedPrintServices[i] == null) { | ||
| cachedPrintServices[i] = new CachedPrintService(javaxPrintServices[i]); | ||
| } | ||
| } | ||
| cachedPrintServicesCopy = cachedPrintServices; | ||
| // Immediately invalidate the defaultPrinter cache | ||
| cachedDefault.get(true); | ||
|
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| return cachedPrintServices; | ||
| } | ||
|
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| private static CachedPrintService getMatch(CachedPrintService[] array, PrintService javaxPrintService) { | ||
| if(array != null) { | ||
| for(CachedPrintService cps : array) { | ||
| // Note: Order of operations can cause the defaultService pointer to differ if lookupDefaultPrintService() | ||
| // is called before lookupPrintServices(...) because the provider will invalidate on refreshServices() if | ||
| // "sun.java2d.print.polling" is set to "false". We're OK with this because worst case, we just | ||
| // call "lpstat" a second time. | ||
| if (cps.getJavaxPrintService() == javaxPrintService) return cps; | ||
| } | ||
| } | ||
| return null; | ||
| } | ||
| } |
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