On Sunday 11 May 2008 11:24, j16sdiz at freenetproject.org wrote:
> Author: j16sdiz
> Date: 2008-05-11 10:24:22 +0000 (Sun, 11 May 2008)
> New Revision: 19891
>
> Modified:
>
branches/saltedhashstore/freenet/src/freenet/store/SaltedHashFreenetStore.java
> Log:
> Quadratic Probing (datastore resize disabled)
Cool! Any test results yet?
>
>
> Modified:
branches/saltedhashstore/freenet/src/freenet/store/SaltedHashFreenetStore.java
> ===================================================================
> ---
branches/saltedhashstore/freenet/src/freenet/store/SaltedHashFreenetStore.java
2008-05-11 09:08:40 UTC (rev 19890)
> +++
branches/saltedhashstore/freenet/src/freenet/store/SaltedHashFreenetStore.java
2008-05-11 10:24:22 UTC (rev 19891)
> @@ -126,22 +126,29 @@
>
> private Entry probeEntry0(byte[] routingKey, long probeStoreSize)
> throws
IOException {
> Entry entry;
> - long offset = getOffsetFromPlainKey(routingKey, probeStoreSize);
> + long[] offset = getOffsetFromPlainKey(routingKey,
> probeStoreSize);
>
> - if (!lockEntry(offset)) {
> - Logger.error(this, "can't lock entry: " + offset);
> - return null;
> + for (int i = 0; i < offset.length; i++) {
> + if (logDEBUG)
> + Logger.debug(this, "probing for i=" + i + ",
> offset=" + offset[i]);
> +
> + if (!lockEntry(offset[i])) {
> + Logger.error(this, "can't lock entry: " +
> offset[i]);
> + continue;
> + }
> + try {
> + entry = readEntry(offset[i], routingKey);
> + } catch (EOFException e) {
> + // may occur on resize, silent it a bit
> + Logger.error(this, "EOFException on
> probeEntry", e);
> + return null;
Shouldn't we go around the loop here? Or are the offsets strictly increasing?
> + } finally {
> + unlockEntry(offset[i]);
> + }
> + if (entry != null)
> + return entry;
> }
> - try {
> - entry = readEntry(offset, routingKey);
> - } catch (EOFException e) {
> - // may occur on resize, silent it a bit
> - Logger.error(this, "EOFException on probeEntry", e);
> - return null;
> - } finally {
> - unlockEntry(offset);
> - }
> - return entry;
> + return null;
> }
>
> public void put(StorableBlock block, byte[] routingKey, byte[] fullKey,
byte[] data, byte[] header,
> @@ -163,16 +170,39 @@
> }
>
> Entry entry = new Entry(routingKey, header, data);
> - if (!lockEntry(entry.getOffset())) {
> + long[] offset = entry.getOffset();
> +
> + for (int i = 0; i < offset.length; i++) {
> + if (!lockEntry(offset[i])) {
> + Logger.error(this, "can't lock entry: " +
> offset[i]);
> + return;
> + }
> + try {
> + if (isFree(offset[i], entry)) {
> + if (logDEBUG)
> + Logger.debug(this, "probing,
> write to i=" + i + ", offset=" +
offset[i]);
> + writeEntry(entry, offset[i]);
> + incWrites();
> + return;
> + }
> + } finally {
> + unlockEntry(offset[i]);
> + }
> + }
> +
> + // no free blocks?
> + int i = random.nextInt(offset.length);
You should try to write to an empty slot, of course... if all are full, is it
better to overwrite an empty slot rather than the first one?
> + if (!lockEntry(offset[i])) {
> Logger.error(this, "can't lock entry: " +
> entry.getOffset());
> - incMisses();
> return;
> }
> try {
> - writeEntry(entry);
> + if (logDEBUG)
> + Logger.debug(this, "collision, write to i=" + i
> + ", offset=" +
offset[i]);
> + writeEntry(entry, offset[i]);
> incWrites();
> } finally {
> - unlockEntry(entry.getOffset());
> + unlockEntry(offset[i]);
> }
> }
>
> @@ -235,6 +265,7 @@
> private byte[] data;
>
> private boolean isEncrypted;
> + public long curOffset;
>
> /**
> * Create a new entry
> @@ -352,7 +383,7 @@
> return block;
> }
>
> - public long getOffset() {
> + public long[] getOffset() {
> if (digestedRoutingKey != null)
> return
> getOffsetFromDigestedKey(digestedRoutingKey, storeSize);
> else
> @@ -382,7 +413,8 @@
> }
> } else {
> // we do not know the plain key, let's check
> the digest
> - if (!Arrays.equals(this.digestedRoutingKey,
getDigestedRoutingKey(routingKey)))
> + if (!Arrays.equals(this.digestedRoutingKey,
> SaltedHashFreenetStore.this
> + .getDigestedRoutingKey(routingKey)))
> return false;
> }
>
> @@ -411,7 +443,7 @@
> header = cipher.blockEncipher(header, 0, header.length);
> data = cipher.blockEncipher(data, 0, data.length);
>
> - digestedRoutingKey =
> getDigestedRoutingKey(plainRoutingKey);
> + getDigestedRoutingKey();
> isEncrypted = true;
> }
>
> @@ -438,6 +470,13 @@
> public boolean isFree() {
> return (flag & ENTRY_FLAG_OCCUPIED) == 0;
> }
> +
> + public byte[] getDigestedRoutingKey() {
> + if (digestedRoutingKey != null)
> + return digestedRoutingKey;
> + else
> + return
SaltedHashFreenetStore.this.getDigestedRoutingKey(this.plainRoutingKey);
> + }
So where does digestedRoutingKey get set?
> }
>
> /**
> @@ -504,6 +543,7 @@
> return null;
> }
>
> + entry.curOffset = offset;
> return entry;
> }
>
> @@ -516,17 +556,12 @@
> * <li>update the entry with latest store size</li>
> * </ul>
> */
> - private void writeEntry(Entry entry) throws IOException {
> + private void writeEntry(Entry entry, long offset) throws IOException {
> entry.encrypt();
>
> - long offset = entry.getOffset();
> int split = (int) (offset % FILE_SPLIT);
> long rawOffset = (offset / FILE_SPLIT) * entryTotalLength;
>
> - if (logMINOR && !isFree(offset)) {
> - Logger.minor(this, "collision, overwritting an entry");
> - }
> -
> ByteBuffer bf = entry.toByteBuffer();
> do {
> int status = storeFC[split].write(bf, rawOffset +
> bf.position());
> @@ -554,16 +589,18 @@
> }
>
> /**
> - * Check if a block is free
> + * Check if a block is free or occupied by a specific routing key
> *
> * @param offset
> + * @param entry
> + * entry, maybe <code>null</code>
> * @throws IOException
> */
> - private boolean isFree(long offset) throws IOException {
> + private boolean isFree(long offset, Entry entry) throws IOException {
> int split = (int) (offset % FILE_SPLIT);
> long rawOffset = (offset / FILE_SPLIT) * entryTotalLength;
>
> - ByteBuffer bf = ByteBuffer.allocate(0x30 + 0x08);
> + ByteBuffer bf = ByteBuffer.allocate((int) ENTRY_HEADER_LENGTH);
>
> do {
> int status = storeFC[split].read(bf, rawOffset +
> bf.position());
> @@ -571,7 +608,17 @@
> throw new EOFException();
> } while (bf.hasRemaining());
>
> - return (bf.getLong(0x30) & ENTRY_FLAG_OCCUPIED) == 0;
> + if ((bf.getLong(0x30) & ENTRY_FLAG_OCCUPIED) == 0) {
> + // free
> + return true;
> + } else if (entry != null) {
> + // check digested key
> + byte[] digestedRoutingKey = new byte[0x20];
> + bf.position(0);
> + bf.get(digestedRoutingKey);
> + return Arrays.equals(digestedRoutingKey,
> entry.getDigestedRoutingKey());
> + }
> + return false;
> }
>
> private void flushAndClose() {
> @@ -689,7 +736,7 @@
> while (!shutdown) {
> synchronized (cleanerLock) {
> if (prevStoreSize != 0)
> - resizeStore();
> + ; //resizeStore();
> else
> estimateStoreSize();
>
> @@ -728,9 +775,11 @@
> */
> private int resizeRound;
>
> - /**
> + /*-
> + *
> + *
> * Move old entries to new location and resize store
> - */
> + *
> private void resizeStore() {
> ++resizeRound;
> Logger.normal(this, "Starting datastore resize (round "
> + resizeRound
+ ")");
> @@ -773,7 +822,7 @@
>
> /**
> * Scan all entries and try to move them
> - */
> + *
> private void moveOldEntry0(boolean queueItem) {
> newEntries = 0;
> oldEntries = 0;
> @@ -827,7 +876,7 @@
> long newOffset =
> entry.getOffset();
>
> if (newOffset == offset) { //
> lucky!
> - writeEntry(entry); //
> write back entry storeSize
> + lockAndWrite(entry); //
> write back entry storeSize
> resolvedEntries++;
> continue;
> }
> @@ -840,7 +889,7 @@
>
> if
> (newOffsetEntry.isFree()) {
> // the new
> offset is freeeeeeee..
> -
> writeEntry(entry);
> +
> lockAndWrite(entry);
>
> freeOffset(offset);
>
> resolvedEntries++;
> } else if
> (newOffsetEntry.getStoreSize() == storeSize) {
> @@ -862,7 +911,7 @@
>
> oldEntries++; // newOffset wasn't counted count it
> }
>
> -
> writeEntry(entry);
> +
> lockAndWrite(entry);
>
> freeOffset(offset);
>
> resolvedEntries++;
> }
> @@ -896,7 +945,7 @@
> * Put back oldItems with best effort
> *
> * @throws IOException
> - */
> + *
> private void putBackOldItems(FileChannel oldItems) throws
> IOException {
> while (true) {
> Entry entry = readOldItem(oldItems);
> @@ -914,7 +963,7 @@
> if (isFree(newOffset)) {
> if (logDEBUG)
> Logger.debug(this, "Put
> back old item: " +
HexUtil.bytesToHex(entry.digestedRoutingKey));
> - writeEntry(entry);
> + lockAndWrite(entry);
> done = true;
> } else {
> if (logDEBUG)
> @@ -948,6 +997,7 @@
> bf.flip();
> return new Entry(bf);
> }
> + */
>
> /**
> * Samples to take on key count estimation
> @@ -972,7 +1022,7 @@
> long occupied = 0;
> while (sampled < numSample) {
> try {
> - if (!isFree(samplePos)) {
> + if (!isFree(samplePos, null)) {
> occupied++;
> }
> sampled++;
> @@ -1173,7 +1223,7 @@
> * @param storeSize
> * @return
> */
> - public long getOffsetFromPlainKey(byte[] plainKey, long storeSize) {
> + public long[] getOffsetFromPlainKey(byte[] plainKey, long storeSize) {
> return
> getOffsetFromDigestedKey(getDigestedRoutingKey(plainKey),
storeSize);
> }
>
> @@ -1184,18 +1234,27 @@
> * @param storeSize
> * @return
> */
> - public long getOffsetFromDigestedKey(byte[] digestedKey, long
> storeSize) {
> - long keyValue = (((long) (digestedKey[0]) << 0) + //
> - (((long) digestedKey[1]) << 8) + //
> - (((long) digestedKey[3]) << 16) + //
> - (((long) digestedKey[4]) << 24) + //
> - (((long) digestedKey[5]) << 32) + //
> - (((long) digestedKey[6]) << 40) + //
> - (((long) digestedKey[7]) << 48))
> - & Long.MAX_VALUE;
> - return keyValue % storeSize;
> + public long[] getOffsetFromDigestedKey(byte[] digestedKey, long
> storeSize)
{
> + long keyValue = keyToLong(digestedKey);
> + // h + 141 i^2 + 13 i
> + return new long[] {//
> + ((keyValue + 141 * (0 * 0) + 13 * 0) & Long.MAX_VALUE) %
> storeSize, // i
= 0
> + ((keyValue + 141 * (1 * 1) + 13 * 1) & Long.MAX_VALUE)
> %
storeSize, // i = 1
> + ((keyValue + 141 * (2 * 2) + 13 * 2) & Long.MAX_VALUE)
> %
storeSize, // i = 2
> + ((keyValue + 141 * (3 * 3) + 13 * 3) & Long.MAX_VALUE)
> %
storeSize, // i = 3
> + };
These are all going to be quite close to keyValue, no? Is this intentional?
> }
>
> + private long keyToLong(byte[] key) {
> + return (((long) (key[0]) << 0) + //
> + (((long) key[1]) << 8) + //
> + (((long) key[3]) << 16) + //
> + (((long) key[4]) << 24) + //
> + (((long) key[5]) << 32) + //
> + (((long) key[6]) << 40) + //
> + (((long) key[7]) << 48));
What about 56?
> + }
> +
> // ------------- Statistics (a.k.a. lies)
> private final Object statLock = new Object();
> private long hits;
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