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Convert connection windows to and from bitmaps.

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This commit is contained in:
akwizgran
2012-10-13 23:59:11 +01:00
parent 7739bcdd06
commit 79c3ef572d
2 changed files with 56 additions and 11 deletions
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33
components/net/sf/briar/transport/ConnectionWindow.java
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@@ -22,20 +22,22 @@ class ConnectionWindow {
}
ConnectionWindow(long centre, byte[] bitmap) {
if(centre < 0 || centre > MAX_32_BIT_UNSIGNED)
if(centre < 0 || centre > MAX_32_BIT_UNSIGNED + 1)
throw new IllegalArgumentException();
if(bitmap.length != CONNECTION_WINDOW_SIZE / 8)
throw new IllegalArgumentException();
unseen = new HashSet<Long>();
long bottom = getBottom(centre);
long top = getTop(centre);
for(long l = bottom; l < top; l++) {
int offset = (int) (l - bottom);
int bytes = offset / 8;
int bits = offset % 8;
if((bitmap[bytes] & (128 >> bits)) == 0) unseen.add(l);
}
this.centre = centre;
unseen = new HashSet<Long>();
long bitmapBottom = centre - CONNECTION_WINDOW_SIZE / 2;
for(int bytes = 0; bytes < bitmap.length; bytes++) {
for(int bits = 0; bits < 8; bits++) {
long connection = bitmapBottom + bytes * 8 + bits;
if(connection >= 0 && connection <= MAX_32_BIT_UNSIGNED) {
if((bitmap[bytes] & (128 >> bits)) == 0)
unseen.add(connection);
}
}
}
}
boolean isSeen(long connection) {
@@ -70,7 +72,16 @@ class ConnectionWindow {
byte[] getBitmap() {
byte[] bitmap = new byte[CONNECTION_WINDOW_SIZE / 8];
// FIXME
long bitmapBottom = centre - CONNECTION_WINDOW_SIZE / 2;
for(int bytes = 0; bytes < bitmap.length; bytes++) {
for(int bits = 0; bits < 8; bits++) {
long connection = bitmapBottom + bytes * 8 + bits;
if(connection >= 0 && connection <= MAX_32_BIT_UNSIGNED) {
if(!unseen.contains(connection))
bitmap[bytes] |= 128 >> bits;
}
}
}
return bitmap;
}

34
test/net/sf/briar/transport/ConnectionWindowTest.java
View File

@@ -1,5 +1,9 @@
package net.sf.briar.transport;
import static net.sf.briar.api.transport.TransportConstants.CONNECTION_WINDOW_SIZE;
import static net.sf.briar.util.ByteUtils.MAX_32_BIT_UNSIGNED;
import static org.junit.Assert.assertArrayEquals;
import java.util.Collection;
import net.sf.briar.BriarTestCase;
@@ -40,6 +44,29 @@ public class ConnectionWindowTest extends BriarTestCase {
w.setSeen(48);
fail();
} catch(IllegalArgumentException expected) {}
// Centre is max - 1, highest value in window is max
byte[] bitmap = new byte[CONNECTION_WINDOW_SIZE / 8];
w = new ConnectionWindow(MAX_32_BIT_UNSIGNED - 1, bitmap);
assertFalse(w.isSeen(MAX_32_BIT_UNSIGNED - 1));
assertFalse(w.isSeen(MAX_32_BIT_UNSIGNED));
// Values greater than max should never be allowed
try {
w.setSeen(MAX_32_BIT_UNSIGNED + 1);
fail();
} catch(IllegalArgumentException expected) {}
w.setSeen(MAX_32_BIT_UNSIGNED);
assertTrue(w.isSeen(MAX_32_BIT_UNSIGNED));
// Centre should have moved to max + 1
assertEquals(MAX_32_BIT_UNSIGNED + 1, w.getCentre());
// The bit corresponding to max should be set
byte[] expectedBitmap = new byte[CONNECTION_WINDOW_SIZE / 8];
expectedBitmap[expectedBitmap.length / 2 - 1] = 1; // 00000001
assertArrayEquals(expectedBitmap, w.getBitmap());
// Values greater than max should never be allowed even if centre > max
try {
w.setSeen(MAX_32_BIT_UNSIGNED + 1);
fail();
} catch(IllegalArgumentException expected) {}
}
@Test
@@ -70,6 +97,13 @@ public class ConnectionWindowTest extends BriarTestCase {
w.setSeen(9);
fail();
} catch(IllegalArgumentException expected) {}
// Centre should still be 26
assertEquals(26, w.getCentre());
// The bits corresponding to 10, 15, 16 and 25 should be set
byte[] expectedBitmap = new byte[CONNECTION_WINDOW_SIZE / 8];
expectedBitmap[0] = (byte) 134; // 10000110
expectedBitmap[1] = 1; // 00000001
assertArrayEquals(expectedBitmap, w.getBitmap());
}
@Test