Bug 572277 - [performance] improve Util.getResourceContentsAsCharArray

Length is ignored anyway because the size in bytes is meaningless when
reading variable sized char encodings (Bug 149028)

Change-Id: I56ab8d4512073bd6466fdfd1e1c3a4c63e82ef7a
Signed-off-by: Joerg Kubitz <jkubitz-eclipse@gmx.de>
Reviewed-on: https://git.eclipse.org/r/c/jdt/eclipse.jdt.core/+/178352
Reviewed-on: https://git.eclipse.org/r/c/jdt/eclipse.jdt.core/+/180028
Reviewed-by: Sravan Kumar Lakkimsetti <sravankumarl@in.ibm.com>
Reviewed-by: Fabrice Tiercelin <fabrice.tiercelin@yahoo.fr>
Tested-by: JDT Bot <jdt-bot@eclipse.org>

9 files changed, 15 insertions, 65 deletions

diff --git a/org.eclipse.jdt.core.tests.model/src/org/eclipse/jdt/core/tests/dom/APIDocumentationTests.java b/org.eclipse.jdt.core.tests.model/src/org/eclipse/jdt/core/tests/dom/APIDocumentationTests.java
index 5a6292da86..6e9dc05f32 100644
--- a/org.eclipse.jdt.core.tests.model/src/org/eclipse/jdt/core/tests/dom/APIDocumentationTests.java
+++ b/org.eclipse.jdt.core.tests.model/src/org/eclipse/jdt/core/tests/dom/APIDocumentationTests.java
@@ -168,7 +168,7 @@ public void testJavaCoreAPI() throws CoreException, IllegalArgumentException, Il
 				try (ZipFile zipFile = new ZipFile(jarFile)) {
 					ZipEntry entry = zipFile.getEntry(PATH_JAVA_CORE_JAVA);
 					try (InputStream inputStream = zipFile.getInputStream(entry)) {
-						sourceChars = Util.getInputStreamAsCharArray(inputStream, (int)entry.getSize(), null);
+						sourceChars = Util.getInputStreamAsCharArray(inputStream, null);
 					}
 				}
 			}
diff --git a/org.eclipse.jdt.core.tests.model/src/org/eclipse/jdt/core/tests/formatter/FormatterRegressionTests.java b/org.eclipse.jdt.core.tests.model/src/org/eclipse/jdt/core/tests/formatter/FormatterRegressionTests.java
index 0f8dd863e6..acf250ad8f 100644
--- a/org.eclipse.jdt.core.tests.model/src/org/eclipse/jdt/core/tests/formatter/FormatterRegressionTests.java
+++ b/org.eclipse.jdt.core.tests.model/src/org/eclipse/jdt/core/tests/formatter/FormatterRegressionTests.java
@@ -151,7 +151,7 @@ public class FormatterRegressionTests extends AbstractJavaModelTests {
 			zipFile = new ZipFile(fileName);
 			ZipEntry zipEntry = zipFile.getEntry(zipEntryName);
 			inputStream = new BufferedInputStream(zipFile.getInputStream(zipEntry));
-			return new String(org.eclipse.jdt.internal.compiler.util.Util.getInputStreamAsCharArray(inputStream, -1, null));
+			return new String(org.eclipse.jdt.internal.compiler.util.Util.getInputStreamAsCharArray(inputStream, null));
 		} catch (IOException e) {
 		} finally {
 			try {
diff --git a/org.eclipse.jdt.core.tests.model/src/org/eclipse/jdt/core/tests/model/EncodingTests.java b/org.eclipse.jdt.core.tests.model/src/org/eclipse/jdt/core/tests/model/EncodingTests.java
index 82315c9a3e..9202f7ca6c 100644
--- a/org.eclipse.jdt.core.tests.model/src/org/eclipse/jdt/core/tests/model/EncodingTests.java
+++ b/org.eclipse.jdt.core.tests.model/src/org/eclipse/jdt/core/tests/model/EncodingTests.java
@@ -722,7 +722,8 @@ public class EncodingTests extends ModifyingResourceTests {
 						return result;
 					}
 				};
-				char[] result = org.eclipse.jdt.internal.compiler.util.Util.getInputStreamAsCharArray(in, (int) file.getLocation().toFile().length(), "UTF-8");
+				char[] result = org.eclipse.jdt.internal.compiler.util.Util.getInputStreamAsCharArray(in,
+						org.eclipse.jdt.internal.compiler.util.Util.UTF_8);
 				assertSourceEquals(
 					"Unexpected source",
 					"abcdefghijklmn",
diff --git a/org.eclipse.jdt.core/batch/org/eclipse/jdt/internal/compiler/batch/ClasspathSourceJar.java b/org.eclipse.jdt.core/batch/org/eclipse/jdt/internal/compiler/batch/ClasspathSourceJar.java
index 126409d443..d906d7bb4b 100644
--- a/org.eclipse.jdt.core/batch/org/eclipse/jdt/internal/compiler/batch/ClasspathSourceJar.java
+++ b/org.eclipse.jdt.core/batch/org/eclipse/jdt/internal/compiler/batch/ClasspathSourceJar.java
@@ -44,7 +44,7 @@ public class ClasspathSourceJar extends ClasspathJar {
 				char[] contents = null;
 				try {
 					stream = this.zipFile.getInputStream(sourceEntry);
-					contents = Util.getInputStreamAsCharArray(stream, -1, this.encoding);
+					contents = Util.getInputStreamAsCharArray(stream, this.encoding);
 				} finally {
 					if (stream != null)
 						stream.close();
diff --git a/org.eclipse.jdt.core/compiler/org/eclipse/jdt/internal/compiler/util/ManifestAnalyzer.java b/org.eclipse.jdt.core/compiler/org/eclipse/jdt/internal/compiler/util/ManifestAnalyzer.java
index 79119d3734..48014f82bb 100644
--- a/org.eclipse.jdt.core/compiler/org/eclipse/jdt/internal/compiler/util/ManifestAnalyzer.java
+++ b/org.eclipse.jdt.core/compiler/org/eclipse/jdt/internal/compiler/util/ManifestAnalyzer.java
@@ -43,7 +43,7 @@ public class ManifestAnalyzer {
 	 * @throws IOException if an exception occurs while analyzing the file
 	 */
 	public boolean analyzeManifestContents(InputStream inputStream) throws IOException {
-		char[] chars = Util.getInputStreamAsCharArray(inputStream, -1, Util.UTF_8);
+		char[] chars = Util.getInputStreamAsCharArray(inputStream, Util.UTF_8);
 		return analyzeManifestContents(chars);
 	}
 
diff --git a/org.eclipse.jdt.core/compiler/org/eclipse/jdt/internal/compiler/util/Util.java b/org.eclipse.jdt.core/compiler/org/eclipse/jdt/internal/compiler/util/Util.java
index 3e489858f4..c5227433dd 100644
--- a/org.eclipse.jdt.core/compiler/org/eclipse/jdt/internal/compiler/util/Util.java
+++ b/org.eclipse.jdt.core/compiler/org/eclipse/jdt/internal/compiler/util/Util.java
@@ -363,7 +363,7 @@ public class Util implements SuffixConstants {
 	 */
 	public static char[] bytesToChar(byte[] bytes, String encoding) throws IOException {
 
-		return getInputStreamAsCharArray(new ByteArrayInputStream(bytes), bytes.length, encoding);
+		return getInputStreamAsCharArray(new ByteArrayInputStream(bytes), encoding);
 
 	}
 
@@ -420,7 +420,7 @@ public class Util implements SuffixConstants {
 		InputStream stream = null;
 		try {
 			stream = new FileInputStream(file);
-			return getInputStreamAsCharArray(stream, (int) file.length(), encoding);
+			return getInputStreamAsCharArray(stream, encoding);
 		} finally {
 			if (stream != null) {
 				try {
@@ -538,37 +538,14 @@ public class Util implements SuffixConstants {
 		return contents;
 	}
 
-	/*
-	 * NIO support to get input stream as char array.
-	 * Not used as with JDK 1.4.2 this support is slower than standard IO one...
-	 * Keep it as comment for future in case of next JDK versions improve performance
-	 * in this area...
-	public static char[] getInputStreamAsCharArray(FileInputStream stream, int length, String encoding)
-		throws IOException {
-
-		FileChannel channel = stream.getChannel();
-		int size = (int)channel.size();
-		if (length >= 0 && length < size) size = length;
-		Charset charset = encoding==null?systemCharset:Charset.forName(encoding);
-		if (charset != null) {
-			MappedByteBuffer bbuffer = channel.map(FileChannel.MapMode.READ_ONLY, 0, size);
-		    CharsetDecoder decoder = charset.newDecoder();
-		    CharBuffer buffer = decoder.decode(bbuffer);
-		    char[] contents = new char[buffer.limit()];
-		    buffer.get(contents);
-		    return contents;
-		}
-		throw new UnsupportedCharsetException(SYSTEM_FILE_ENCODING);
-	}
-	*/
 	/**
 	 * Returns the given input stream's contents as a character array.
-	 * If a length is specified (i.e. if length != -1), this represents the number of bytes in the stream.
 	 * Note this doesn't close the stream.
 	 * @throws IOException if a problem occured reading the stream.
 	 */
-	public static char[] getInputStreamAsCharArray(InputStream stream, int length, String encoding)
+	public static char[] getInputStreamAsCharArray(InputStream stream,  String encoding)
 			throws IOException {
+		//XXX java.nio.file.Files.readString().toCharArray() is faster on recent JDKs
 		BufferedReader reader = null;
 		try {
 			reader = encoding == null
@@ -578,21 +555,12 @@ public class Util implements SuffixConstants {
 			// encoding is not supported
 			reader =  new BufferedReader(new InputStreamReader(stream));
 		}
-		char[] contents;
+		char[] contents = CharOperation.NO_CHAR;
 		int totalRead = 0;
-		if (length == -1) {
-			contents = CharOperation.NO_CHAR;
-		} else {
-			// length is a good guess when the encoding produces less or the same amount of characters than the file length
-			contents = new char[length]; // best guess
-		}
 
 		while (true) {
 			int amountRequested;
-			if (totalRead < length) {
-				// until known length is met, reuse same array sized eagerly
-				amountRequested = length - totalRead;
-			} else {
+			{
 				// reading beyond known length
 				int current = reader.read();
 				if (current < 0) break;
diff --git a/org.eclipse.jdt.core/model/org/eclipse/jdt/internal/core/ClasspathEntry.java b/org.eclipse.jdt.core/model/org/eclipse/jdt/internal/core/ClasspathEntry.java
index 629c80b587..38f8857d9a 100644
--- a/org.eclipse.jdt.core/model/org/eclipse/jdt/internal/core/ClasspathEntry.java
+++ b/org.eclipse.jdt.core/model/org/eclipse/jdt/internal/core/ClasspathEntry.java
@@ -1038,7 +1038,7 @@ public class ClasspathEntry implements IClasspathEntry {
 				return null;
 			}
 			inputStream = zip.getInputStream(manifest);
-			char[] chars = getInputStreamAsCharArray(inputStream, -1, UTF_8);
+			char[] chars = getInputStreamAsCharArray(inputStream, UTF_8);
 			return chars;
 		} finally {
 			if (inputStream != null) {
diff --git a/org.eclipse.jdt.core/model/org/eclipse/jdt/internal/core/util/Util.java b/org.eclipse.jdt.core/model/org/eclipse/jdt/internal/core/util/Util.java
index 97dd9efe33..9f602c6ebc 100644
--- a/org.eclipse.jdt.core/model/org/eclipse/jdt/internal/core/util/Util.java
+++ b/org.eclipse.jdt.core/model/org/eclipse/jdt/internal/core/util/Util.java
@@ -1187,25 +1187,6 @@ public class Util {
 	}
 
 	public static char[] getResourceContentsAsCharArray(IFile file, String encoding) throws JavaModelException {
-		// Get file length
-		// workaround https://bugs.eclipse.org/bugs/show_bug.cgi?id=130736 by using java.io.File if possible
-		IPath location = file.getLocation();
-		long length;
-		if (location == null) {
-			// non local file
-			try {
-				URI locationURI = file.getLocationURI();
-				if (locationURI == null)
-					throw new CoreException(new Status(IStatus.ERROR, JavaCore.PLUGIN_ID, Messages.bind(Messages.file_notFound, file.getFullPath().toString())));
-				length = EFS.getStore(locationURI).fetchInfo().getLength();
-			} catch (CoreException e) {
-				throw new JavaModelException(e, IJavaModelStatusConstants.ELEMENT_DOES_NOT_EXIST);
-			}
-		} else {
-			// local file
-			length = location.toFile().length();
-		}
-
 		// Get resource contents
 		InputStream stream= null;
 		try {
@@ -1214,7 +1195,7 @@ public class Util {
 			throw new JavaModelException(e, IJavaModelStatusConstants.ELEMENT_DOES_NOT_EXIST);
 		}
 		try {
-			return org.eclipse.jdt.internal.compiler.util.Util.getInputStreamAsCharArray(stream, (int) length, encoding);
+			return org.eclipse.jdt.internal.compiler.util.Util.getInputStreamAsCharArray(stream, encoding);
 		} catch (IOException e) {
 			throw new JavaModelException(e, IJavaModelStatusConstants.IO_EXCEPTION);
 		} finally {
diff --git a/org.eclipse.jdt.core/search/org/eclipse/jdt/internal/core/nd/indexer/Indexer.java b/org.eclipse.jdt.core/search/org/eclipse/jdt/internal/core/nd/indexer/Indexer.java
index 5bbb6446d5..722e116411 100644
--- a/org.eclipse.jdt.core/search/org/eclipse/jdt/internal/core/nd/indexer/Indexer.java
+++ b/org.eclipse.jdt.core/search/org/eclipse/jdt/internal/core/nd/indexer/Indexer.java
@@ -750,7 +750,7 @@ public final class Indexer {
 
 								if (fileName.equals(TypeConstants.META_INF_MANIFEST_MF)) {
 									try (InputStream inputStream = zipFile.getInputStream(member)) {
-										char[] chars = getInputStreamAsCharArray(inputStream, -1, UTF_8);
+										char[] chars = getInputStreamAsCharArray(inputStream, UTF_8);
 
 										resourceFile.setManifestContent(chars);
 									}