garydgregory commented on a change in pull request #101: IO-649 - Improve the
performance of the contentEquals() methods.
URL: https://github.com/apache/commons-io/pull/101#discussion_r370778595
##########
File path: src/main/java/org/apache/commons/io/IOUtils.java
##########
@@ -691,80 +692,173 @@ public static void closeQuietly(final Writer output) {
}
/**
- * Compares the contents of two Streams to determine if they are equal or
- * not.
+ * Compares the contents of two Streams to determine if they are equal or
not.
* <p>
- * This method buffers the input internally using
- * <code>BufferedInputStream</code> if they are not already buffered.
- * </p>
+ * This method buffers the input internally using {@link
#DEFAULT_BUFFER_SIZE} sized buffers.
*
* @param input1 the first stream
* @param input2 the second stream
* @return true if the content of the streams are equal or they both don't
* exist, false otherwise
- * @throws NullPointerException if either input is null
* @throws IOException if an I/O error occurs
*/
@SuppressWarnings("resource")
public static boolean contentEquals(final InputStream input1, final
InputStream input2)
throws IOException {
+ return contentEquals(input1, input2, DEFAULT_BUFFER_SIZE);
+ }
+
+ /**
+ * Compares the contents of two Streams to determine if they are equal or
not.
+ * <p>
+ * This method buffers the input internally.
+ *
+ * @param input1 the first stream
+ * @param input2 the second stream
+ * @param bufferSize the size of the internal buffer to use.
+ * @return true if the content of the streams are equal or they both don't
+ * exist, false otherwise
+ * @throws IllegalArgumentException if bufferSize is less than or equal to
zero.
+ * @throws IOException if an I/O error occurs
+ * @since 2.6
+ */
+ @SuppressWarnings("resource")
+ public static boolean contentEquals(final InputStream input1, final
InputStream input2, final int bufferSize)
+ throws IOException {
+ if (bufferSize <= 0) {
+ throw new IllegalArgumentException("Buffer size must be positive:
" + bufferSize);
+ }
+
if (input1 == input2) {
return true;
}
if (input1 == null ^ input2 == null) {
return false;
}
- final BufferedInputStream bufferedInput1 = buffer(input1);
- final BufferedInputStream bufferedInput2 = buffer(input2);
- int ch = bufferedInput1.read();
- while (EOF != ch) {
- final int ch2 = bufferedInput2.read();
- if (ch != ch2) {
+
+ int input1NumBytesRead = 0;
+ int input2NumBytesRead = 0;
+ final byte[] input1Buffer = new byte[bufferSize];
+ final byte[] input2Buffer = new byte[bufferSize];
+ do {
+ input1NumBytesRead = fillBuffer(input1, input1Buffer);
+ input2NumBytesRead = fillBuffer(input2, input2Buffer);
+
+ if (input2NumBytesRead != input1NumBytesRead ||
!Arrays.equals(input1Buffer, input2Buffer)) {
return false;
}
- ch = bufferedInput1.read();
- }
- return bufferedInput2.read() == EOF;
+ } while (input1NumBytesRead == bufferSize && input2NumBytesRead ==
bufferSize);
+
+ return input1.read() == EOF && input2.read() == EOF;
}
+
/**
- * Compares the contents of two Readers to determine if they are equal or
- * not.
+ * This method fills the provided byte array buffer from the provided
<code>InputStream</code>. When this method
+ * returns the buffer will either be full or the InputStream will be fully
consumed.
+ *
+ * @param inputStream the InputStream from which to read
+ * @param buffer the buffer to fill
+ * @return the number of bytes placed in the buffer. If this is equal to
<code>buffer.length</code> then the
+ * buffer was completely filled. If it is less than
<code>buffer.length</code>, then the InputStream has been
+ * fully consumed.
+ * @throws IOException if an I/O error occurs.
+ */
+ private static int fillBuffer(final InputStream inputStream, final byte[]
buffer) throws IOException {
+ int totalBytesRead = 0;
+ int bytesRead = 0;
+ do {
+ totalBytesRead += bytesRead;
+ bytesRead = inputStream.read(buffer, totalBytesRead, buffer.length
- totalBytesRead);
+ } while (bytesRead != -1 && totalBytesRead < buffer.length);
+
+ return totalBytesRead;
+ }
+
+ /**
+ * Compares the contents of two Readers to determine if they are equal or
not.
* <p>
- * This method buffers the input internally using
- * <code>BufferedReader</code> if they are not already buffered.
+ * This method buffers the input internally using {@link
#DEFAULT_BUFFER_SIZE} sized buffers.
* </p>
*
* @param input1 the first reader
* @param input2 the second reader
* @return true if the content of the readers are equal or they both don't
* exist, false otherwise
- * @throws NullPointerException if either input is null
* @throws IOException if an I/O error occurs
* @since 1.1
*/
@SuppressWarnings("resource")
public static boolean contentEquals(final Reader input1, final Reader
input2)
throws IOException {
+ return contentEquals(input1, input2, DEFAULT_BUFFER_SIZE);
+ }
+
+ /**
+ * Compares the contents of two Readers to determine if they are equal or
not.
+ * <p>
+ * This method buffers the input internally.
+ * </p>
+ *
+ * @param input1 the first reader
+ * @param input2 the second reader
+ * @param bufferSize the size of the internal buffer to use.
+ * @return true if the content of the readers are equal or they both don't
+ * exist, false otherwise
+ * @throws IllegalArgumentException if bufferSize is less than or equal to
zero.
+ * @throws IOException if an I/O error occurs
+ * @since 2.6
+ */
+ @SuppressWarnings("resource")
+ public static boolean contentEquals(final Reader input1, final Reader
input2, final int bufferSize)
+ throws IOException {
+ if (bufferSize <= 0) {
+ throw new IllegalArgumentException("Buffer size must be positive:
" + bufferSize);
+ }
+
if (input1 == input2) {
return true;
}
if (input1 == null ^ input2 == null) {
return false;
}
- final BufferedReader bufferedInput1 = toBufferedReader(input1);
- final BufferedReader bufferedInput2 = toBufferedReader(input2);
- int ch = bufferedInput1.read();
- while (EOF != ch) {
- final int ch2 = bufferedInput2.read();
- if (ch != ch2) {
+ int input1NumCharsRead = 0;
+ int input2NumCharsRead = 0;
+ final char[] input1Buffer = new char[bufferSize];
+ final char[] input2Buffer = new char[bufferSize];
+ do {
+ input1NumCharsRead = fillBuffer(input1, input1Buffer);
+ input2NumCharsRead = fillBuffer(input2, input2Buffer);
+
+ if (input2NumCharsRead != input1NumCharsRead ||
!Arrays.equals(input1Buffer, input2Buffer)) {
return false;
}
- ch = bufferedInput1.read();
- }
+ } while (input1NumCharsRead == bufferSize && input2NumCharsRead ==
bufferSize);
+
+ return input1.read() == EOF && input2.read() == EOF;
+ }
+
+ /**
+ * This method fills the provided byte array buffer from the provided
<code>Reader</code>. When this method
+ * returns the buffer will either be full or the InputStream will be fully
consumed.
+ *
+ * @param reader the Reader from which to read
+ * @param buffer the buffer to fill
+ * @return the number of chars placed in the buffer. If this is equal to
<code>buffer.length</code> then the
+ * buffer was completely filled. If it is less than
<code>buffer.length</code>, then the Reader has been
+ * fully consumed.
+ * @throws IOException if an I/O error occurs.
+ */
+ private static int fillBuffer(final Reader reader, final char[] buffer)
throws IOException {
+ int totalBytesRead = 0;
+ int bytesRead = 0;
+ do {
+ totalBytesRead += bytesRead;
+ bytesRead = reader.read(buffer, totalBytesRead, buffer.length -
totalBytesRead);
+ } while (bytesRead != -1 && totalBytesRead < buffer.length);
Review comment:
Magic number; use EOF.
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