Layoutlib: Read and close XML files as soon as possible.

Because passing an InputStream to KXML does not close the
stream after the file has been parsed, the files are staying
locked on windows until the gc and finalizers are run.

This change preload the XML files and close their stream,
and then pass the content in a stream to the parser.

Change-Id: Iabe27989dc616ec9e7de88e52b1ec3af9f007f7c

Author: Xavier Ducrohet

tools/layoutlib/bridge/src/com/android/layoutlib/bridge/impl/ParserFactory.java

@@ -21,9 +21,12 @@
 import org.xmlpull.v1.XmlPullParser;
 import org.xmlpull.v1.XmlPullParserException;
 
+import java.io.BufferedInputStream;
+import java.io.ByteArrayInputStream;
 import java.io.File;
 import java.io.FileInputStream;
 import java.io.FileNotFoundException;
+import java.io.IOException;
 import java.io.InputStream;
 
 /**
@@ -38,14 +41,21 @@ public class ParserFactory {
 
     public static XmlPullParser create(File f)
             throws XmlPullParserException, FileNotFoundException {
-        KXmlParser parser = instantiateParser(f.getName());
-        parser.setInput(new FileInputStream(f), ENCODING);
-        return parser;
+        InputStream stream = new FileInputStream(f);
+        return create(stream, f.getName(), f.length());
     }
 
     public static XmlPullParser create(InputStream stream, String name)
+        throws XmlPullParserException {
+        return create(stream, name, -1);
+    }
+
+    private static XmlPullParser create(InputStream stream, String name, long size)
             throws XmlPullParserException {
         KXmlParser parser = instantiateParser(name);
+
+        stream = readAndClose(stream, name, size);
+
         parser.setInput(stream, ENCODING);
         return parser;
     }
@@ -61,6 +71,61 @@ private static KXmlParser instantiateParser(String name) throws XmlPullParserExc
         return parser;
     }
 
+    private static InputStream readAndClose(InputStream stream, String name, long size)
+            throws XmlPullParserException {
+        // just a sanity check. It's doubtful we'll have such big files!
+        if (size > Integer.MAX_VALUE) {
+            throw new XmlPullParserException("File " + name + " is too big to be parsed");
+        }
+        int intSize = (int) size;
+
+        // create a buffered reader to facilitate reading.
+        BufferedInputStream bufferedStream = new BufferedInputStream(stream);
+        try {
+            int avail;
+            if (intSize != -1) {
+                avail = intSize;
+            } else {
+                // get the size to read.
+                avail = bufferedStream.available();
+            }
+
+            // create the initial buffer and read it.
+            byte[] buffer = new byte[avail];
+            int read = stream.read(buffer);
+
+            // this is the easy case.
+            if (read == intSize) {
+                return new ByteArrayInputStream(buffer);
+            }
+
+            // check if there is more to read (read() does not necessarily read all that
+            // available() returned!)
+            while ((avail = bufferedStream.available()) > 0) {
+                if (read + avail > buffer.length) {
+                    // just allocate what is needed. We're mostly reading small files
+                    // so it shouldn't be too problematic.
+                    byte[] moreBuffer = new byte[read + avail];
+                    System.arraycopy(buffer, 0, moreBuffer, 0, read);
+                    buffer = moreBuffer;
+                }
+
+                read += stream.read(buffer, read, avail);
+            }
+
+            // return a new stream encapsulating this buffer.
+            return new ByteArrayInputStream(buffer);
+
+        } catch (IOException e) {
+            throw new XmlPullParserException("Failed to read " + name, null, e);
+        } finally {
+            try {
+                bufferedStream.close();
+            } catch (IOException e) {
+            }
+        }
+    }
+
     private static class CustomParser extends KXmlParser {
         private final String mName;