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Code Issues Projects Releases Wiki Activity

Fixed the frame reordering window.

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This commit is contained in:
akwizgran
2012-01-20 11:26:10 +00:00
parent 92b67d9881
commit 5a4505cb71
5 changed files with 106 additions and 114 deletions
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16
components/net/sf/briar/transport/FrameWindow.java
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@@ -2,21 +2,15 @@ package net.sf.briar.transport;
interface FrameWindow { interface FrameWindow {
/** Returns true if the given number is too high to fit in the window. */
boolean isTooHigh(long frameNumber);
/** Returns true if the given number is in the window. */ /** Returns true if the given number is in the window. */
boolean contains(long frameNumber); boolean contains(long frameNumber);
/** /**
* Advances the window so it is centred on the given number, unless the * Removes the given number from the window and advances the window.
* centre is already greater than the number. Returns false if the window * Returns false if the given number is not in the window.
* is unmodifiable.
*/
boolean advance(long frameNumber);
/**
* Removes the given number from the window and, if the number is greater
* than or equal to the window's centre, advances the centre to one greater
* than the given number. Returns false if the given number is not in the
* window or the window is unmodifiable.
*/ */
boolean remove(long frameNumber); boolean remove(long frameNumber);
} }

60
components/net/sf/briar/transport/FrameWindowImpl.java
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@@ -5,18 +5,23 @@ import static net.sf.briar.util.ByteUtils.MAX_32_BIT_UNSIGNED;
import java.util.Collection; import java.util.Collection;
import java.util.HashSet; import java.util.HashSet;
import java.util.Iterator;
class FrameWindowImpl implements FrameWindow { class FrameWindowImpl implements FrameWindow {
private final Collection<Long> window; private final Collection<Long> window;
private long centre; private long base;
FrameWindowImpl() { FrameWindowImpl() {
window = new HashSet<Long>(); window = new HashSet<Long>();
for(long l = 0; l < FRAME_WINDOW_SIZE / 2; l++) window.add(l); fill(0, FRAME_WINDOW_SIZE);
centre = 0; base = 0;
}
public boolean isTooHigh(long frameNumber) {
if(frameNumber < 0 || frameNumber > MAX_32_BIT_UNSIGNED)
throw new IllegalArgumentException();
return frameNumber >= base + FRAME_WINDOW_SIZE;
} }
public boolean contains(long frameNumber) { public boolean contains(long frameNumber) {
@@ -25,39 +30,32 @@ class FrameWindowImpl implements FrameWindow {
return window.contains(frameNumber); return window.contains(frameNumber);
} }
public boolean advance(long frameNumber) {
if(frameNumber < 0 || frameNumber > MAX_32_BIT_UNSIGNED)
throw new IllegalArgumentException();
if(frameNumber <= centre) return true;
// Remove values that have passed out of the window
long newBottom = getBottom(frameNumber);
Iterator<Long> it = window.iterator();
while(it.hasNext()) if(it.next() < newBottom) it.remove();
// Add values that have passed into the window
long fillFrom = Math.max(newBottom, getTop(centre) + 1);
long newTop = getTop(frameNumber);
for(long l = fillFrom; l <= newTop; l++) window.add(l);
centre = frameNumber;
return true;
}
public boolean remove(long frameNumber) { public boolean remove(long frameNumber) {
if(frameNumber < 0 || frameNumber > MAX_32_BIT_UNSIGNED) if(frameNumber < 0 || frameNumber > MAX_32_BIT_UNSIGNED)
throw new IllegalArgumentException(); throw new IllegalArgumentException();
if(!window.remove(frameNumber)) return false; if(!window.remove(frameNumber)) return false;
if(frameNumber >= centre && frameNumber < MAX_32_BIT_UNSIGNED) if(frameNumber == base) {
advance(frameNumber + 1); // Find the new base
if(window.isEmpty()) {
base += FRAME_WINDOW_SIZE;
fill(base, base + FRAME_WINDOW_SIZE);
} else {
for(long l = base; l < base + FRAME_WINDOW_SIZE; l++) {
if(window.contains(l)) {
fill(base + FRAME_WINDOW_SIZE, l + FRAME_WINDOW_SIZE);
base = l;
break;
}
}
}
}
return true; return true;
} }
// Returns the lowest value contained in a window with the given centre private void fill(long from, long to) {
private static long getBottom(long centre) { for(long l = from; l < to; l++) {
return Math.max(0, centre - FRAME_WINDOW_SIZE / 2); if(l <= MAX_32_BIT_UNSIGNED) window.add(l);
} else return;
}
// Returns the highest value contained in a window with the given centre
private static long getTop(long centre) {
return Math.min(MAX_32_BIT_UNSIGNED,
centre + FRAME_WINDOW_SIZE / 2 - 1);
} }
} }

22
components/net/sf/briar/transport/NullFrameWindow.java
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@@ -1,20 +1,28 @@
package net.sf.briar.transport; package net.sf.briar.transport;
import static net.sf.briar.util.ByteUtils.MAX_32_BIT_UNSIGNED;
class NullFrameWindow implements FrameWindow { class NullFrameWindow implements FrameWindow {
private long centre = 0L; private long base = 0L;
public boolean contains(long frameNumber) { public boolean isTooHigh(long frameNumber) {
return frameNumber == centre; if(frameNumber < 0 || frameNumber > MAX_32_BIT_UNSIGNED)
throw new IllegalArgumentException();
return frameNumber != base;
} }
public boolean advance(long frameNumber) { public boolean contains(long frameNumber) {
return frameNumber == centre; if(frameNumber < 0 || frameNumber > MAX_32_BIT_UNSIGNED)
throw new IllegalArgumentException();
return frameNumber == base;
} }
public boolean remove(long frameNumber) { public boolean remove(long frameNumber) {
if(frameNumber != centre) return false; if(frameNumber < 0 || frameNumber > MAX_32_BIT_UNSIGNED)
centre++; throw new IllegalArgumentException();
if(frameNumber != base) return false;
base++;
return true; return true;
} }
} }

3
components/net/sf/briar/transport/NullIncomingReliabilityLayer.java
View File

@@ -15,8 +15,7 @@ class NullIncomingReliabilityLayer implements IncomingReliabilityLayer {
public boolean readFrame(Frame f) throws IOException, InvalidDataException { public boolean readFrame(Frame f) throws IOException, InvalidDataException {
if(!in.readFrame(f, window)) return false; if(!in.readFrame(f, window)) return false;
long frameNumber = HeaderEncoder.getFrameNumber(f.getBuffer()); long frameNumber = HeaderEncoder.getFrameNumber(f.getBuffer());
if(!window.remove(frameNumber) && window.advance(frameNumber)) if(!window.remove(frameNumber)) throw new IllegalStateException();
throw new RuntimeException();
return true; return true;
} }
} }

119
test/net/sf/briar/transport/FrameWindowImplTest.java
View File

@@ -1,8 +1,7 @@
package net.sf.briar.transport; package net.sf.briar.transport;
import net.sf.briar.BriarTestCase;
import static net.sf.briar.api.transport.TransportConstants.FRAME_WINDOW_SIZE; import static net.sf.briar.api.transport.TransportConstants.FRAME_WINDOW_SIZE;
import static net.sf.briar.util.ByteUtils.MAX_32_BIT_UNSIGNED; import net.sf.briar.BriarTestCase;
import org.junit.Test; import org.junit.Test;
@@ -13,77 +12,71 @@ public class FrameWindowImplTest extends BriarTestCase {
FrameWindow w = new FrameWindowImpl(); FrameWindow w = new FrameWindowImpl();
for(int i = 0; i < 100; i++) { for(int i = 0; i < 100; i++) {
assertTrue(w.contains(i)); assertTrue(w.contains(i));
w.remove(i); assertTrue(w.remove(i));
assertFalse(w.contains(i)); assertFalse(w.contains(i));
} }
for(int i = 100; i < 100 + FRAME_WINDOW_SIZE; i++) {
assertTrue(w.contains(i));
assertFalse(w.isTooHigh(i));
}
assertFalse(w.contains(100 + FRAME_WINDOW_SIZE));
assertTrue(w.isTooHigh(100 + FRAME_WINDOW_SIZE));
} }
@Test @Test
public void testWindowJumping() { public void testWindowJumping() {
FrameWindow w = new FrameWindowImpl(); FrameWindow w = new FrameWindowImpl();
for(int i = 0; i < 100; i += 13) { // Base of the window is 0
for(int i = 0; i < FRAME_WINDOW_SIZE; i++) assertTrue(w.contains(i));
assertFalse(w.contains(FRAME_WINDOW_SIZE));
assertFalse(w.isTooHigh(FRAME_WINDOW_SIZE - 1));
assertTrue(w.isTooHigh(FRAME_WINDOW_SIZE));
// Remove all numbers except 0 and 5
for(int i = 1; i < 5; i++) assertTrue(w.remove(i));
for(int i = 6; i < FRAME_WINDOW_SIZE; i++) assertTrue(w.remove(i));
// Base of the window should still be 0
assertTrue(w.contains(0));
for(int i = 1; i < 5; i++) assertFalse(w.contains(i));
assertTrue(w.contains(5));
for(int i = 6; i < FRAME_WINDOW_SIZE; i++) assertFalse(w.contains(i));
assertFalse(w.contains(FRAME_WINDOW_SIZE));
assertFalse(w.isTooHigh(FRAME_WINDOW_SIZE - 1));
assertTrue(w.isTooHigh(FRAME_WINDOW_SIZE));
// Remove 0
assertTrue(w.remove(0));
// Base of the window should now be 5
for(int i = 0; i < 5; i++) assertFalse(w.contains(i));
assertTrue(w.contains(5));
for(int i = 6; i < FRAME_WINDOW_SIZE; i++) assertFalse(w.contains(i));
for(int i = FRAME_WINDOW_SIZE; i < FRAME_WINDOW_SIZE + 5; i++) {
assertTrue(w.contains(i)); assertTrue(w.contains(i));
w.remove(i); }
assertFalse(w.contains(FRAME_WINDOW_SIZE + 5));
assertFalse(w.isTooHigh(FRAME_WINDOW_SIZE + 4));
assertTrue(w.isTooHigh(FRAME_WINDOW_SIZE + 5));
// Remove all numbers except 5
for(int i = FRAME_WINDOW_SIZE; i < FRAME_WINDOW_SIZE + 5; i++) {
assertTrue(w.remove(i));
}
// Base of the window should still be 5
assertTrue(w.contains(5));
for(int i = 6; i < FRAME_WINDOW_SIZE + 5; i++) {
assertFalse(w.contains(i)); assertFalse(w.contains(i));
} }
} assertFalse(w.contains(FRAME_WINDOW_SIZE + 5));
assertFalse(w.isTooHigh(FRAME_WINDOW_SIZE + 4));
@Test assertTrue(w.isTooHigh(FRAME_WINDOW_SIZE + 5));
public void testWindowUpperLimit() { // Remove 5
FrameWindow w = new FrameWindowImpl(); assertTrue(w.remove(5));
// Centre is 0, highest value in window is 15 // Base of the window should now be FRAME_WINDOW_SIZE + 5
for(int i = 0; i < 16; i++) assertTrue(w.contains(i)); for(int i = 0; i < FRAME_WINDOW_SIZE + 5; i++) {
assertFalse(w.remove(16)); assertFalse(w.contains(i));
assertTrue(w.remove(15));
assertFalse(w.remove(15));
// Centre is 16, highest value in window is 31
for(int i = 0; i < 32; i++) assertEquals(i != 15, w.contains(i));
assertFalse(w.remove(32));
assertTrue(w.remove(31));
// Values greater than 2^32 - 1 should never be allowed
assertTrue(w.advance(MAX_32_BIT_UNSIGNED - 1));
assertTrue(w.remove(MAX_32_BIT_UNSIGNED - 1));
assertTrue(w.remove(MAX_32_BIT_UNSIGNED));
try {
w.remove(MAX_32_BIT_UNSIGNED + 1);
fail();
} catch(IllegalArgumentException expected) {}
}
@Test
public void testAdvance() {
FrameWindow w = new FrameWindowImpl();
long centre = 0;
for(int i = 0; i < 10; i++) {
long bottom = Math.max(0, centre - FRAME_WINDOW_SIZE / 2);
long top = Math.min(MAX_32_BIT_UNSIGNED,
centre + FRAME_WINDOW_SIZE / 2 - 1);
if(bottom > 0) assertFalse(w.contains(bottom - 1));
for(long j = bottom; j <= top; j++) assertTrue(w.contains(j));
if(top < MAX_32_BIT_UNSIGNED) assertFalse(w.contains(top + 1));
centre += 12345;
assertTrue(w.advance(centre));
} }
} for(int i = FRAME_WINDOW_SIZE + 5; i < FRAME_WINDOW_SIZE * 2 + 5; i++) {
assertTrue(w.contains(i));
@Test }
public void testWindowLowerLimit() { assertFalse(w.contains(FRAME_WINDOW_SIZE * 2 + 5));
FrameWindow w = new FrameWindowImpl(); assertFalse(w.isTooHigh(FRAME_WINDOW_SIZE * 2 + 4));
// Centre is 0, negative values should never be allowed assertTrue(w.isTooHigh(FRAME_WINDOW_SIZE * 2 + 5));
try {
w.remove(-1);
fail();
} catch(IllegalArgumentException expected) {}
// Slide the window twice
assertTrue(w.remove(15));
assertTrue(w.remove(16));
// Centre is 17, lowest value in window is 1
assertFalse(w.remove(0));
assertTrue(w.remove(1));
// Slide the window
assertTrue(w.remove(25));
// Centre is 26, lowest value in window is 10
assertFalse(w.remove(9));
assertTrue(w.remove(10));
} }
} }