Revert "Bug 572277 - [performance] improve Util.getResourceContentsAsCharArray"I20210430-1800

This reverts commit 141932dc82a2da30d55c83ad27de394755693779.

Change-Id: Ib7005e634583e3b8cb2b9f96d2c6c0a0523c2263
Reviewed-on: https://git.eclipse.org/r/c/jdt/eclipse.jdt.core/+/180025
Tested-by: Manoj Palat <manpalat@in.ibm.com>
Reviewed-by: Manoj Palat <manpalat@in.ibm.com>

9 files changed, 61 insertions, 15 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 6e9dc05f32..5a6292da86 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, null);
+						sourceChars = Util.getInputStreamAsCharArray(inputStream, (int)entry.getSize(), 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 acf250ad8f..0f8dd863e6 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, null));
+			return new String(org.eclipse.jdt.internal.compiler.util.Util.getInputStreamAsCharArray(inputStream, -1, 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 9202f7ca6c..82315c9a3e 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
@@ -722,8 +722,7 @@ public class EncodingTests extends ModifyingResourceTests {
 						return result;
 					}
 				};
-				char[] result = org.eclipse.jdt.internal.compiler.util.Util.getInputStreamAsCharArray(in,
-						org.eclipse.jdt.internal.compiler.util.Util.UTF_8);
+				char[] result = org.eclipse.jdt.internal.compiler.util.Util.getInputStreamAsCharArray(in, (int) file.getLocation().toFile().length(), "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 d906d7bb4b..126409d443 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, this.encoding);
+					contents = Util.getInputStreamAsCharArray(stream, -1, 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 48014f82bb..79119d3734 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, Util.UTF_8);
+		char[] chars = Util.getInputStreamAsCharArray(inputStream, -1, 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 c5227433dd..3e489858f4 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), encoding);
+		return getInputStreamAsCharArray(new ByteArrayInputStream(bytes), bytes.length, encoding);
 
 	}
 
@@ -420,7 +420,7 @@ public class Util implements SuffixConstants {
 		InputStream stream = null;
 		try {
 			stream = new FileInputStream(file);
-			return getInputStreamAsCharArray(stream, encoding);
+			return getInputStreamAsCharArray(stream, (int) file.length(), encoding);
 		} finally {
 			if (stream != null) {
 				try {
@@ -538,14 +538,37 @@ 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,  String encoding)
+	public static char[] getInputStreamAsCharArray(InputStream stream, int length, String encoding)
 			throws IOException {
-		//XXX java.nio.file.Files.readString().toCharArray() is faster on recent JDKs
 		BufferedReader reader = null;
 		try {
 			reader = encoding == null
@@ -555,12 +578,21 @@ public class Util implements SuffixConstants {
 			// encoding is not supported
 			reader =  new BufferedReader(new InputStreamReader(stream));
 		}
-		char[] contents = CharOperation.NO_CHAR;
+		char[] contents;
 		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 38f8857d9a..629c80b587 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, UTF_8);
+			char[] chars = getInputStreamAsCharArray(inputStream, -1, 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 dab92a8979..97dd9efe33 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
@@ -1190,6 +1190,21 @@ public class Util {
 		// 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;
@@ -1199,7 +1214,7 @@ public class Util {
 			throw new JavaModelException(e, IJavaModelStatusConstants.ELEMENT_DOES_NOT_EXIST);
 		}
 		try {
-			return org.eclipse.jdt.internal.compiler.util.Util.getInputStreamAsCharArray(stream, encoding);
+			return org.eclipse.jdt.internal.compiler.util.Util.getInputStreamAsCharArray(stream, (int) length, 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 722e116411..5bbb6446d5 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, UTF_8);
+										char[] chars = getInputStreamAsCharArray(inputStream, -1, UTF_8);
 
 										resourceFile.setManifestContent(chars);
 									}