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Allow Uid#decodeId to decode from a byte array slice (#26987)
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Today we only allow to decode byte arrays where the data has a 0 offset
and the same length as the array. Allowing to decode stuff from a slice will
make decoding IDs cheaper if the the ID is for instance coming from a term dictionary
or BytesRef.

Relates to #26931
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@s1monw
s1monw committed Oct 12, 2017
1 parent 1c3e02c commit ca1930e
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Showing 2 changed files with 72 additions and 47 deletions.
96 changes: 52 additions & 44 deletions core/src/main/java/org/elasticsearch/index/mapper/Uid.java
View file
Original file line number Diff line number Diff line change
Expand Up @@ -135,36 +135,36 @@ static boolean isURLBase64WithoutPadding(String id) {
// 'xxx=' and 'xxx' could be considered the same id
final int length = id.length();
switch (length & 0x03) {
case 0:
break;
case 1:
return false;
case 2:
// the last 2 symbols (12 bits) are encoding 1 byte (8 bits)
// so the last symbol only actually uses 8-6=2 bits and can only take 4 values
char last = id.charAt(length - 1);
if (last != 'A' && last != 'Q' && last != 'g' && last != 'w') {
case 0:
break;
case 1:
return false;
}
break;
case 3:
// The last 3 symbols (18 bits) are encoding 2 bytes (16 bits)
// so the last symbol only actually uses 16-12=4 bits and can only take 16 values
last = id.charAt(length - 1);
if (last != 'A' && last != 'E' && last != 'I' && last != 'M' && last != 'Q'&& last != 'U'&& last != 'Y'
case 2:
// the last 2 symbols (12 bits) are encoding 1 byte (8 bits)
// so the last symbol only actually uses 8-6=2 bits and can only take 4 values
char last = id.charAt(length - 1);
if (last != 'A' && last != 'Q' && last != 'g' && last != 'w') {
return false;
}
break;
case 3:
// The last 3 symbols (18 bits) are encoding 2 bytes (16 bits)
// so the last symbol only actually uses 16-12=4 bits and can only take 16 values
last = id.charAt(length - 1);
if (last != 'A' && last != 'E' && last != 'I' && last != 'M' && last != 'Q'&& last != 'U'&& last != 'Y'
&& last != 'c'&& last != 'g'&& last != 'k' && last != 'o' && last != 's' && last != 'w'
&& last != '0' && last != '4' && last != '8') {
return false;
}
break;
default:
// number & 0x03 is always in [0,3]
throw new AssertionError("Impossible case");
return false;
}
break;
default:
// number & 0x03 is always in [0,3]
throw new AssertionError("Impossible case");
}
for (int i = 0; i < length; ++i) {
final char c = id.charAt(i);
final boolean allowed =
(c >= '0' && c <= '9') ||
(c >= '0' && c <= '9') ||
(c >= 'A' && c <= 'Z') ||
(c >= 'a' && c <= 'z') ||
c == '-' || c == '_';
Expand Down Expand Up @@ -244,16 +244,16 @@ public static BytesRef encodeId(String id) {
}
}

private static String decodeNumericId(byte[] idBytes) {
assert Byte.toUnsignedInt(idBytes[0]) == NUMERIC;
int length = (idBytes.length - 1) * 2;
private static String decodeNumericId(byte[] idBytes, int offset, int len) {
assert Byte.toUnsignedInt(idBytes[offset]) == NUMERIC;
int length = (len - 1) * 2;
char[] chars = new char[length];
for (int i = 1; i < idBytes.length; ++i) {
final int b = Byte.toUnsignedInt(idBytes[i]);
for (int i = 1; i < len; ++i) {
final int b = Byte.toUnsignedInt(idBytes[offset + i]);
final int b1 = (b >>> 4);
final int b2 = b & 0x0f;
chars[(i - 1) * 2] = (char) (b1 + '0');
if (i == idBytes.length - 1 && b2 == 0x0f) {
if (i == len - 1 && b2 == 0x0f) {
length--;
break;
}
Expand All @@ -262,33 +262,41 @@ private static String decodeNumericId(byte[] idBytes) {
return new String(chars, 0, length);
}

private static String decodeUtf8Id(byte[] idBytes) {
assert Byte.toUnsignedInt(idBytes[0]) == UTF8;
return new BytesRef(idBytes, 1, idBytes.length - 1).utf8ToString();
private static String decodeUtf8Id(byte[] idBytes, int offset, int length) {
assert Byte.toUnsignedInt(idBytes[offset]) == UTF8;
return new BytesRef(idBytes, offset + 1, length - 1).utf8ToString();
}

private static String decodeBase64Id(byte[] idBytes) {
assert Byte.toUnsignedInt(idBytes[0]) <= BASE64_ESCAPE;
if (Byte.toUnsignedInt(idBytes[0]) == BASE64_ESCAPE) {
idBytes = Arrays.copyOfRange(idBytes, 1, idBytes.length);
private static String decodeBase64Id(byte[] idBytes, int offset, int length) {
assert Byte.toUnsignedInt(idBytes[offset]) <= BASE64_ESCAPE;
if (Byte.toUnsignedInt(idBytes[offset]) == BASE64_ESCAPE) {
idBytes = Arrays.copyOfRange(idBytes, offset + 1, offset + length);
} else if ((idBytes.length == length && offset == 0) == false) { // no need to copy if it's not a slice
idBytes = Arrays.copyOfRange(idBytes, offset, offset + length);
}
return Base64.getUrlEncoder().withoutPadding().encodeToString(idBytes);
}

/** Decode an indexed id back to its original form.
* @see #encodeId */
public static String decodeId(byte[] idBytes) {
if (idBytes.length == 0) {
return decodeId(idBytes, 0, idBytes.length);
}

/** Decode an indexed id back to its original form.
* @see #encodeId */
public static String decodeId(byte[] idBytes, int offset, int length) {
if (length == 0) {
throw new IllegalArgumentException("Ids can't be empty");
}
final int magicChar = Byte.toUnsignedInt(idBytes[0]);
final int magicChar = Byte.toUnsignedInt(idBytes[offset]);
switch (magicChar) {
case NUMERIC:
return decodeNumericId(idBytes);
case UTF8:
return decodeUtf8Id(idBytes);
default:
return decodeBase64Id(idBytes);
case NUMERIC:
return decodeNumericId(idBytes, offset, length);
case UTF8:
return decodeUtf8Id(idBytes, offset, length);
default:
return decodeBase64Id(idBytes, offset, length);
}
}
}
23 changes: 20 additions & 3 deletions core/src/test/java/org/elasticsearch/index/mapper/UidTests.java
View file
Original file line number Diff line number Diff line change
Expand Up @@ -79,7 +79,7 @@ public void testEncodeUTF8Ids() {
for (int iter = 0; iter < iters; ++iter) {
final String id = TestUtil.randomRealisticUnicodeString(random(), 1, 10);
BytesRef encoded = Uid.encodeId(id);
assertEquals(id, Uid.decodeId(Arrays.copyOfRange(encoded.bytes, encoded.offset, encoded.offset + encoded.length)));
assertEquals(id, doDecodeId(encoded));
assertTrue(encoded.length <= 1 + new BytesRef(id).length);
}
}
Expand All @@ -93,7 +93,7 @@ public void testEncodeNumericIds() {
id = "0" + id;
}
BytesRef encoded = Uid.encodeId(id);
assertEquals(id, Uid.decodeId(Arrays.copyOfRange(encoded.bytes, encoded.offset, encoded.offset + encoded.length)));
assertEquals(id, doDecodeId(encoded));
assertEquals(1 + (id.length() + 1) / 2, encoded.length);
}
}
Expand All @@ -105,9 +105,26 @@ public void testEncodeBase64Ids() {
random().nextBytes(binaryId);
final String id = Base64.getUrlEncoder().withoutPadding().encodeToString(binaryId);
BytesRef encoded = Uid.encodeId(id);
assertEquals(id, Uid.decodeId(Arrays.copyOfRange(encoded.bytes, encoded.offset, encoded.offset + encoded.length)));
assertEquals(id, doDecodeId(encoded));
assertTrue(encoded.length <= 1 + binaryId.length);
}
}

private static String doDecodeId(BytesRef encoded) {

if (randomBoolean()) {
return Uid.decodeId(Arrays.copyOfRange(encoded.bytes, encoded.offset, encoded.offset + encoded.length));
} else {
if (randomBoolean()) {
BytesRef slicedCopy = new BytesRef(randomIntBetween(encoded.length + 1, encoded.length + 100));
slicedCopy.offset = randomIntBetween(1, slicedCopy.bytes.length - encoded.length);
slicedCopy.length = encoded.length;
System.arraycopy(encoded.bytes, encoded.offset, slicedCopy.bytes, slicedCopy.offset, encoded.length);
assertArrayEquals(Arrays.copyOfRange(encoded.bytes, encoded.offset, encoded.offset + encoded.length),
Arrays.copyOfRange(slicedCopy.bytes, slicedCopy.offset, slicedCopy.offset + slicedCopy.length));
encoded = slicedCopy;
}
return Uid.decodeId(encoded.bytes, encoded.offset, encoded.length);
}
}
}

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