From 8b8d32e4960f456c202286df2ce6971b65590c39 Mon Sep 17 00:00:00 2001
From: zzz <zzz@mail.i2p>
Date: Mon, 18 Dec 2017 22:23:42 +0000
Subject: [PATCH] Util: LookaheadInputStream speedups and cleanups
---
.../net/i2p/util/LookaheadInputStream.java | 74 ++++++++++++-------
1 file changed, 49 insertions(+), 25 deletions(-)
diff --git a/core/java/src/net/i2p/util/LookaheadInputStream.java b/core/java/src/net/i2p/util/LookaheadInputStream.java
index 67d48e87ad..cb5b5ca5ca 100644
--- a/core/java/src/net/i2p/util/LookaheadInputStream.java
+++ b/core/java/src/net/i2p/util/LookaheadInputStream.java
@@ -6,15 +6,19 @@ import java.io.IOException;
import java.io.InputStream;
import java.util.Arrays;
+import net.i2p.data.DataHelper;
+
/**
* Simple lookahead buffer to keep the last K bytes in reserve,
* configured to easily be reused. Currently only used by the
- * ResettableGZIPInputStream
- *
+ * ResettableGZIPInputStream.
*/
public class LookaheadInputStream extends FilterInputStream {
private boolean _eofReached;
private final byte[] _footerLookahead;
+ private final int size;
+ // Next byte to read.
+ private int index;
private static final InputStream _fakeInputStream = new ByteArrayInputStream(new byte[0]);
/**
@@ -29,6 +33,7 @@ public class LookaheadInputStream extends FilterInputStream {
public LookaheadInputStream(int lookaheadSize) {
super(_fakeInputStream);
_footerLookahead = new byte[lookaheadSize];
+ size = lookaheadSize;
}
public boolean getEOFReached() { return _eofReached; }
@@ -37,41 +42,33 @@ public class LookaheadInputStream extends FilterInputStream {
* Start the LookaheadInputStream with the given input stream.
* Resets everything if the LookaheadInputStream was previously used.
* WARNING - blocking until lookaheadSize bytes are read!
+ *
+ * @throws IOException if less than lookaheadSize bytes could be read.
*/
public void initialize(InputStream src) throws IOException {
in = src;
_eofReached = false;
- Arrays.fill(_footerLookahead, (byte)0x00);
- int footerRead = 0;
- while (footerRead < _footerLookahead.length) {
- int read = in.read(_footerLookahead, footerRead, _footerLookahead.length - footerRead);
- if (read == -1) throw new IOException("EOF reading the footer lookahead");
- footerRead += read;
- }
+ index = 0;
+ DataHelper.read(in, _footerLookahead);
}
@Override
public int read() throws IOException {
if (_eofReached)
- return -1; //throw new IOException("Already past the EOF");
+ return -1;
int c = in.read();
if (c == -1) {
_eofReached = true;
return -1;
}
- int rv = _footerLookahead[0];
- // FIXME use an index!!!!!!!!!!!!
- System.arraycopy(_footerLookahead, 1, _footerLookahead, 0, _footerLookahead.length-1);
- _footerLookahead[_footerLookahead.length-1] = (byte)c;
- if (rv < 0) rv += 256;
+ int rv = _footerLookahead[index] & 0xff;
+ _footerLookahead[index] = (byte)c;
+ index++;
+ if (index >= size)
+ index = 0;
return rv;
}
- @Override
- public int read(byte buf[]) throws IOException {
- return read(buf, 0, buf.length);
- }
-
@Override
public int read(byte buf[], int off, int len) throws IOException {
if (_eofReached)
@@ -90,8 +87,32 @@ public class LookaheadInputStream extends FilterInputStream {
return len;
}
- /** grab the lookahead footer */
- public byte[] getFooter() { return _footerLookahead; }
+ /**
+ * Grab the lookahead footer.
+ * This will be of size lookaheadsize given in constructor.
+ * The last byte received will be in the last byte of the array.
+ */
+ public byte[] getFooter() {
+ if (index == 0)
+ return _footerLookahead;
+ byte[] rv = new byte[size];
+ System.arraycopy(_footerLookahead, index, rv, 0, size - index);
+ System.arraycopy(_footerLookahead, 0, rv, size - index, index);
+ return rv;
+ }
+
+ /**
+ * @since 0.9.33
+ */
+ @Override
+ public long skip(long n) throws IOException {
+ long rv = 0;
+ int c;
+ while (rv < n && (c = read()) >= 0) {
+ rv++;
+ }
+ return rv;
+ }
/*******
public static void main(String args[]) {
@@ -111,14 +132,17 @@ public class LookaheadInputStream extends FilterInputStream {
for (int i = 0; i < 8; i++)
if (lis.getFooter()[i] != (byte)(i+24))
throw new RuntimeException("Error at footer " + i + " [" + lis.getFooter()[i] + "]");
- System.out.println("Everything is fine in general");
} catch (Exception e) {
e.printStackTrace();
}
for (int i = 9; i < 32*1024; i++) {
- if (!test(i)) break;
+ if (!test(i)) {
+ System.out.println("Everything is NOT fine at size=" + i);
+ break;
+ }
}
+ System.out.println("Everything is fine in general");
}
private static boolean test(int size) {
@@ -137,7 +161,7 @@ public class LookaheadInputStream extends FilterInputStream {
for (int i = 0; i < 8; i++)
if (lis.getFooter()[i] != buf[i+(size-8)])
throw new RuntimeException("Error at footer " + i + " [" + lis.getFooter()[i] + "]");
- System.out.println("Everything is fine at size=" + size);
+ //System.out.println("Everything is fine at size=" + size);
return true;
} catch (Exception e) {
e.printStackTrace();
--
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