Add caching features into Transform filter

src/net/furfurylic/chionographis/CachingResolver.java

@@ -0,0 +1,241 @@
+/*
+ * Chionographis
+ *
+ * These codes are licensed under CC0.
+ * https://creativecommons.org/publicdomain/zero/1.0/deed
+ */
+
+package net.furfurylic.chionographis;
+
+import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
+import java.io.DataInputStream;
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.net.URI;
+import java.nio.file.Paths;
+import java.util.Collections;
+import java.util.IdentityHashMap;
+import java.util.Map;
+import java.util.Optional;
+import java.util.WeakHashMap;
+import java.util.function.Consumer;
+import java.util.function.Function;
+
+import javax.xml.parsers.DocumentBuilder;
+import javax.xml.parsers.DocumentBuilderFactory;
+import javax.xml.parsers.ParserConfigurationException;
+import javax.xml.transform.Source;
+import javax.xml.transform.TransformerException;
+import javax.xml.transform.URIResolver;
+import javax.xml.transform.dom.DOMSource;
+
+import org.w3c.dom.Document;
+import org.xml.sax.EntityResolver;
+import org.xml.sax.InputSource;
+import org.xml.sax.SAXException;
+
+final class CachingResolver implements EntityResolver, URIResolver {
+
+    private static final NetResourceCache<byte[]> BYTES = new NetResourceCache<>();
+    private static final NetResourceCache<Source> TREES = new NetResourceCache<>();
+
+    private Consumer<URI> listenStored_;
+    private Consumer<URI> listenHit_;
+
+    public CachingResolver(Consumer<URI> listenStored, Consumer<URI> listenHit) {
+        listenStored_ = listenStored;
+        listenHit_ = listenHit;
+    }
+
+    @Override
+    public InputSource resolveEntity(String publicId, String systemId)
+            throws SAXException, IOException {
+        if (systemId == null) {
+            return null;
+        }
+        URI uri = URI.create(systemId);
+        uri = uniquifyURI(uri);
+        if (uri == null) {
+            return null;
+        }
+
+        Optional<byte[]> cached = BYTES.accessCache(uri, listenStored_, listenHit_, u -> {
+            try {
+                if (u.getScheme().toLowerCase().equals("file")) {
+                    File file = new File(u);
+                    long length = file.length();
+                    if (length <= Integer.MAX_VALUE) {
+                        byte[] content = new byte[(int) length];
+                        try (DataInputStream in = new DataInputStream(new FileInputStream(file))) {
+                            in.readFully(content);
+                        }
+                        return content;
+                    }
+                }
+                byte[] buffer = new byte[4096];
+                ByteArrayOutputStream bytes = new ByteArrayOutputStream();
+                try (InputStream in = u.toURL().openStream()) {
+                    int length;
+                    while ((length = in.read(buffer)) != -1) {
+                        bytes.write(buffer, 0, length);
+                    }
+                }
+                return bytes.toByteArray();
+            } catch (IOException e) {
+                return null;
+            }
+        });
+
+        if (cached.isPresent()) {
+            InputSource inputSource = new InputSource(new ByteArrayInputStream(cached.get()));
+            inputSource.setSystemId(systemId);
+            inputSource.setPublicId(publicId);
+            return inputSource;            
+        } else {
+            return null;
+        }
+    }
+
+    @Override
+    public Source resolve(String href, String base) throws TransformerException {
+        URI uri;
+        if (base == null) {
+            uri = URI.create(href);
+        } else {
+            uri = URI.create(base).resolve(href);
+        }
+        uri = uniquifyURI(uri);
+        if (uri == null) {
+            return null;
+        }
+
+        Optional<Source> cached = TREES.accessCache(uri, listenStored_, listenHit_, u -> {
+            DocumentBuilderFactory dbfac = DocumentBuilderFactory.newInstance();
+            dbfac.setNamespaceAware(true);
+            try {
+                DocumentBuilder builder = dbfac.newDocumentBuilder();
+                builder.setEntityResolver(this);
+                Document document = builder.parse(u.toString());
+                return new DOMSource(document, u.toString());
+            } catch (ParserConfigurationException | SAXException | IOException e) {
+                return null;
+            }
+        });
+        return cached.orElse(null);
+    }
+
+    /**
+     * Normalizes a URI in terms of its logical content.
+     * 
+     * @param uri
+     *      a URI to normalize.
+     *      
+     * @return
+     *      the normalized URI.
+     */
+    private static URI uniquifyURI(URI uri) {
+        assert uri != null;
+        if (!uri.isAbsolute()) {
+            return null;
+        }
+        if (uri.getScheme().toLowerCase().equals("file")) {
+            // Afraid that omission of "xx/../" may break path meanings for symbolic links
+            try {
+                uri = Paths.get(uri).toRealPath().toUri();                    
+            } catch (IOException e) {
+                return null;
+            }
+        } else {
+            uri = uri.normalize();
+        }
+        return uri;
+    }
+
+    private static class NetResourceCache<T> {
+
+        private final Object LOCK = new Object();
+
+        /** A synchronized canonicalization mapping for URIs. */
+        private Map<URI, URI> canonURIs_;
+
+        /** A possibly identity-based synchronized map. */
+        private Map<URI, Optional<T>> cache_;
+
+        /**
+         * 
+         * @param uri
+         *      a URI. 
+         * @param factory
+         *      a factory function which make an object from a URI.
+         *
+         * @return
+         *      a possibly-empty resolved object.
+         */
+        public Optional<T> accessCache(URI uri,
+                Consumer<URI> listenStored, Consumer<URI> listenHit,
+                Function<URI, ? extends T> factory) {
+            assert uri != null;
+            assert uri.isAbsolute();
+
+            synchronized (LOCK) {
+                if (cache_ == null) {
+                    canonURIs_ = Collections.synchronizedMap(new WeakHashMap<URI, URI>());
+                    cache_ = Collections.synchronizedMap(new IdentityHashMap<>());
+                }
+            }        
+
+            // Get the canonicalized form
+            URI canonicalizedURI = canonicalizeURI(uri);
+
+            // From here uri shall not be in the canonicalized form
+            if (canonicalizedURI == uri) {
+                uri = URI.create(uri.toString());
+            }
+
+            // Lock with privately-canonicalized form
+            synchronized (canonicalizedURI) {
+                Optional<T> cached = cache_.get(canonicalizedURI);
+                if (cached != null) {
+                    if (!cached.isPresent()) {
+                        // Means that an error occurred in the previous try.
+                        return null;
+                    } else {
+                        // Cache hit.
+                        listenHit.accept(uri);
+                    }
+                } else {
+                    cached = Optional.<T>ofNullable(factory.apply(uri));
+                    if (cached.isPresent()) {
+                        listenStored.accept(uri);
+                    }
+                    cache_.put(canonicalizedURI, cached);
+                }
+                return cached;
+            }
+        }        
+
+        /**
+         * Canonicalizes a URI so that URIs which have the same logical content are one same object. 
+         * 
+         * @param uri
+         *      a URI to canonicalize.
+         *      
+         * @return
+         *      the canonicalized form of the URI,
+         *      which is different object from the parameter <i>uri</i>
+         *      if it did not come from this method.
+         */
+        private URI canonicalizeURI(URI uri) {
+            assert uri != null;
+            URI existing = canonURIs_.putIfAbsent(uri, uri);
+            if (existing == null) {
+                return uri;
+            } else {
+                return existing;
+            }
+        }
+    }
+}

src/net/furfurylic/chionographis/Chionographis.java

@@ -53,14 +53,17 @@ public final class Chionographis extends MatchingTask implements SinkDriver {
 
     private Path srcDir_;
     private Path baseDir_;
+    private boolean usesCache_;
     private int prefixCount_;
+
     private Map<String, String> prefixMap_;
     private Sinks sinks_;
 
     /**
      * Sole constructor.
      */
     public Chionographis() {
+        usesCache_ = false;
     }
 
     /**
@@ -100,6 +103,10 @@ public void setSrcDir(String srcDir) {
         srcDir_ = Paths.get(srcDir);
     }
 
+    public void setCache(boolean cache) {
+        usesCache_ = cache;
+    }
+
     /**
      * Adds a prefix-namespace URI mapping entry to this task.
      *
@@ -280,6 +287,11 @@ public void execute() {
                     } else {
                         sinks_.log(this, "  PI search not required", LogLevel.DEBUG);
                     }
+                    if (usesCache_) {
+                        reader.setEntityResolver(new CachingResolver(
+                            u -> sinks_.log(this, "Caching " + u, LogLevel.DEBUG),
+                            u -> sinks_.log(this, "Reusing " + u, LogLevel.DEBUG)));
+                    }
 
                     // Do processing.
                     identity.transform(new SAXSource(reader, input), result);

src/net/furfurylic/chionographis/Transform.java

@@ -42,18 +42,22 @@ public final class Transform extends Sink implements SinkDriver {
 
     private Sinks sinks_;
     private String style_;
+    private boolean usesCache_;
     private int paramCount_;
 
     private SAXTransformerFactory tfac_;
     private URI styleURI_;
 
     private Templates stylesheet_;
-    private Map<String, Object> params_; 
+    private CachingResolver resolver_;
+    private Map<String, Object> params_;
 
     private String output_;
 
     Transform(Logger logger) {
         sinks_ = new Sinks(logger);
+        style_ = null;
+        usesCache_ = false;
         paramCount_ = 0;
         params_ = Collections.<String, Object>emptyMap();
     }
@@ -71,6 +75,10 @@ public void setStyle(String style) {
     }
     // TODO: Make this class able to accept non-file stylesheet URI
 
+    public void setCache(boolean cache) {
+        usesCache_ = cache;
+    }
+
     /**
      * Adds a stylesheet parameter.
      * 
@@ -200,12 +208,21 @@ Result startOne(int originalSrcIndex, String originalSrcFileName) {
                 tfac_ = (SAXTransformerFactory) TransformerFactory.newInstance();
                 String styleSystemID = styleURI_.toString();
                 sinks_.log(this, "Compiling stylesheet: " + styleSystemID, LogLevel.VERBOSE);
+                if (usesCache_) {
+                    resolver_ = new CachingResolver(
+                        u -> sinks_.log(this, "Caching " + u, LogLevel.DEBUG),
+                        u -> sinks_.log(this, "Reusing " + u, LogLevel.DEBUG));
+                    tfac_.setURIResolver(resolver_);
+                }
                 stylesheet_ = tfac_.newTemplates(new StreamSource(styleSystemID));
             }
             TransformerHandler styler = tfac_.newTransformerHandler(stylesheet_);
             for (Map.Entry<String, Object> param : params_.entrySet()) {
                 styler.getTransformer().setParameter(param.getKey(), param.getValue());
             }
+            if (usesCache_) {
+                styler.getTransformer().setURIResolver(resolver_);
+            }
             styler.setResult(sinks_.startOne(originalSrcIndex, originalSrcFileName));
             ContentHandler handler;
             if (sinks_.needsOutput()) {
@@ -314,6 +331,6 @@ public void processingInstruction(String target, String data) throws SAXExceptio
         @Override
         public void skippedEntity(String name) throws SAXException {
             handler_.skippedEntity(name);
-        }        
+        }
     }
 }

test/crossing/input-cache/X.txt

@@ -0,0 +1 @@
+X

test/crossing/input-cache/base.xsl

@@ -0,0 +1,4 @@
+<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">
+<xsl:output method="text"/>
+<xsl:template match="*"><xsl:value-of select="local-name(.)"/>=<xsl:value-of select="."/></xsl:template>
+</xsl:stylesheet>

test/crossing/input-cache/expected1.txt

@@ -0,0 +1 @@
+a=100

test/crossing/input-cache/expected2.txt

@@ -0,0 +1 @@
+***x=X***

test/crossing/input-cache/external.xml

@@ -0,0 +1,6 @@
+<?xml version="1.0" standalone="no"?>
+<!DOCTYPE map SYSTEM "input.dtd">
+<map>
+	<a>&OneHundred;</a>
+	<b>200</b>
+</map>

test/crossing/input-cache/input.dtd

@@ -0,0 +1,2 @@
+<!ENTITY X SYSTEM "X.txt">
+<!ENTITY OneHundred "100">

test/crossing/input-cache/input.xml

@@ -0,0 +1,3 @@
+<?xml version="1.0" standalone="no"?>
+<!DOCTYPE x SYSTEM "input.dtd">
+<x>&X;</x>

test/crossing/input-cache/style1.xsl

@@ -0,0 +1,5 @@
+<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">
+<xsl:include href="base.xsl"/>
+<xsl:variable name="external" select="document('external.xml')"/>
+<xsl:template match="/"><xsl:apply-templates select="$external//a"/></xsl:template>
+</xsl:stylesheet>

test/crossing/input-cache/style2.xsl

@@ -0,0 +1,4 @@
+<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">
+<xsl:import href="base.xsl"/>
+<xsl:template match="/">***<xsl:apply-imports/>***</xsl:template>
+</xsl:stylesheet>