Optimize ObjectID sort and serdes

bson/src/main/org/bson/types/ObjectId.java

@@ -16,17 +16,18 @@
 
 package org.bson.types;
 
+import static org.bson.assertions.Assertions.isTrueArgument;
+import static org.bson.assertions.Assertions.notNull;
+
 import java.io.InvalidObjectException;
 import java.io.ObjectInputStream;
 import java.io.Serializable;
 import java.nio.ByteBuffer;
+import java.nio.ByteOrder;
 import java.security.SecureRandom;
 import java.util.Date;
 import java.util.concurrent.atomic.AtomicInteger;
 
-import static org.bson.assertions.Assertions.isTrueArgument;
-import static org.bson.assertions.Assertions.notNull;
-
 /**
  * <p>A globally unique identifier for objects.</p>
  *
@@ -53,9 +54,8 @@ public final class ObjectId implements Comparable<ObjectId>, Serializable {
  private static final int OBJECT_ID_LENGTH = 12;
  private static final int LOW_ORDER_THREE_BYTES = 0x00ffffff;
 
- // Use primitives to represent the 5-byte random value.
- private static final int RANDOM_VALUE1;
- private static final short RANDOM_VALUE2;
+ // Use upper bytes of a long to represent the 5-byte random value.
+ private static final long RANDOM_VALUE;
 
  private static final AtomicInteger NEXT_COUNTER;
 
@@ -67,18 +67,12 @@ public final class ObjectId implements Comparable<ObjectId>, Serializable {
  * The timestamp
  */
  private final int timestamp;
+
  /**
- * The counter.
- */
- private final int counter;
- /**
- * the first four bits of randomness.
- */
- private final int randomValue1;
- /**
- * The last two bits of randomness.
+ * The final 8 bytes of the ObjectID are 5 bytes probabilistically unique to the machine and
+ * process, followed by a 3 byte incrementing counter initialized to a random value.
  */
- private final short randomValue2;
+ private final long nonce;
 
  /**
  * Gets a new object id.
@@ -101,7 +95,7 @@ public static ObjectId get() {
  * @since 4.1
  */
  public static ObjectId getSmallestWithDate(final Date date) {
- return new ObjectId(dateToTimestampSeconds(date), 0, (short) 0, 0, false);
+ return new ObjectId(dateToTimestampSeconds(date), 0L);
  }
 
  /**
@@ -152,7 +146,7 @@ public ObjectId() {
  * @param date the date
  */
  public ObjectId(final Date date) {
- this(dateToTimestampSeconds(date), NEXT_COUNTER.getAndIncrement() & LOW_ORDER_THREE_BYTES, false);
+ this(dateToTimestampSeconds(date), RANDOM_VALUE | (NEXT_COUNTER.getAndIncrement() & LOW_ORDER_THREE_BYTES));
  }
 
  /**
@@ -163,7 +157,7 @@ public ObjectId(final Date date) {
  * @throws IllegalArgumentException if the high order byte of counter is not zero
  */
  public ObjectId(final Date date, final int counter) {
- this(dateToTimestampSeconds(date), counter, true);
+ this(dateToTimestampSeconds(date), getNonceFromUntrustedCounter(counter));
  }
 
  /**
@@ -174,25 +168,19 @@ public ObjectId(final Date date, final int counter) {
  * @throws IllegalArgumentException if the high order byte of counter is not zero
  */
  public ObjectId(final int timestamp, final int counter) {
- this(timestamp, counter, true);
+ this(timestamp, getNonceFromUntrustedCounter(counter));
  }
 
- private ObjectId(final int timestamp, final int counter, final boolean checkCounter) {
- this(timestamp, RANDOM_VALUE1, RANDOM_VALUE2, counter, checkCounter);
+ private ObjectId(final int timestamp, final long nonce) {
+ this.timestamp = timestamp;
+ this.nonce = nonce;
  }
 
- private ObjectId(final int timestamp, final int randomValue1, final short randomValue2, final int counter,
- final boolean checkCounter) {
- if ((randomValue1 & 0xff000000) != 0) {
- throw new IllegalArgumentException("The random value must be between 0 and 16777215 (it must fit in three bytes).");
- }
- if (checkCounter && ((counter & 0xff000000) != 0)) {
+ private static long getNonceFromUntrustedCounter(final int counter) {
+ if ((counter & 0xff000000) != 0) {
  throw new IllegalArgumentException("The counter must be between 0 and 16777215 (it must fit in three bytes).");
  }
- this.timestamp = timestamp;
- this.counter = counter & LOW_ORDER_THREE_BYTES;
- this.randomValue1 = randomValue1;
- this.randomValue2 = randomValue2;
+ return RANDOM_VALUE | counter;
  }
 
  /**
@@ -226,12 +214,14 @@ public ObjectId(final ByteBuffer buffer) {
  notNull("buffer", buffer);
  isTrueArgument("buffer.remaining() >=12", buffer.remaining() >= OBJECT_ID_LENGTH);
 
- // Note: Cannot use ByteBuffer.getInt because it depends on tbe buffer's byte order
- // and ObjectId's are always in big-endian order.
- timestamp = makeInt(buffer.get(), buffer.get(), buffer.get(), buffer.get());
- randomValue1 = makeInt((byte) 0, buffer.get(), buffer.get(), buffer.get());
- randomValue2 = makeShort(buffer.get(), buffer.get());
- counter = makeInt((byte) 0, buffer.get(), buffer.get(), buffer.get());
+ ByteOrder originalOrder = buffer.order();
+ try {
+ buffer.order(ByteOrder.BIG_ENDIAN);
+ this.timestamp = buffer.getInt();
+ this.nonce = buffer.getLong();
+ } finally {
+ buffer.order(originalOrder);
+ }
  }
 
  /**
@@ -240,9 +230,11 @@ public ObjectId(final ByteBuffer buffer) {
  * @return the byte array
  */
  public byte[] toByteArray() {
- ByteBuffer buffer = ByteBuffer.allocate(OBJECT_ID_LENGTH);
- putToByteBuffer(buffer);
- return buffer.array(); // using .allocate ensures there is a backing array that can be returned
+ // using .allocate ensures there is a backing array that can be returned
+ return ByteBuffer.allocate(OBJECT_ID_LENGTH)
+ .putInt(this.timestamp)
+ .putLong(this.nonce)
+ .array();
  }
 
  /**
@@ -257,18 +249,14 @@ public void putToByteBuffer(final ByteBuffer buffer) {
  notNull("buffer", buffer);
  isTrueArgument("buffer.remaining() >=12", buffer.remaining() >= OBJECT_ID_LENGTH);
 
- buffer.put(int3(timestamp));
- buffer.put(int2(timestamp));
- buffer.put(int1(timestamp));
- buffer.put(int0(timestamp));
- buffer.put(int2(randomValue1));
- buffer.put(int1(randomValue1));
- buffer.put(int0(randomValue1));
- buffer.put(short1(randomValue2));
- buffer.put(short0(randomValue2));
- buffer.put(int2(counter));
- buffer.put(int1(counter));
- buffer.put(int0(counter));
+ ByteOrder originalOrder = buffer.order();
+ try {
+ buffer.order(ByteOrder.BIG_ENDIAN);
+ buffer.putInt(this.timestamp);
+ buffer.putLong(this.nonce);
+ } finally {
+ buffer.order(originalOrder);
+ }
  }
 
  /**
@@ -313,49 +301,26 @@ public boolean equals(final Object o) {
  return false;
  }
 
- ObjectId objectId = (ObjectId) o;
-
- if (counter != objectId.counter) {
- return false;
- }
- if (timestamp != objectId.timestamp) {
- return false;
- }
-
- if (randomValue1 != objectId.randomValue1) {
+ ObjectId other = (ObjectId) o;
+ if (timestamp != other.timestamp) {
  return false;
  }
-
- if (randomValue2 != objectId.randomValue2) {
- return false;
- }
-
- return true;
+ return nonce == other.nonce;
  }
 
  @Override
  public int hashCode() {
- int result = timestamp;
- result = 31 * result + counter;
- result = 31 * result + randomValue1;
- result = 31 * result + randomValue2;
- return result;
+ return 31 * timestamp + Long.hashCode(nonce);
  }
 
  @Override
  public int compareTo(final ObjectId other) {
- if (other == null) {
- throw new NullPointerException();
+ int cmp = Integer.compareUnsigned(this.timestamp, other.timestamp);
+ if (cmp != 0) {
+ return cmp;
  }
 
- byte[] byteArray = toByteArray();
- byte[] otherByteArray = other.toByteArray();
- for (int i = 0; i < OBJECT_ID_LENGTH; i++) {
- if (byteArray[i] != otherByteArray[i]) {
- return ((byteArray[i] & 0xff) < (otherByteArray[i] & 0xff)) ? -1 : 1;
- }
- }
- return 0;
+ return Long.compareUnsigned(nonce, other.nonce);
  }
 
  @Override
@@ -407,8 +372,7 @@ private Object readResolve() {
  static {
  try {
  SecureRandom secureRandom = new SecureRandom();
- RANDOM_VALUE1 = secureRandom.nextInt(0x01000000);
- RANDOM_VALUE2 = (short) secureRandom.nextInt(0x00008000);
+ RANDOM_VALUE = secureRandom.nextLong() & ~LOW_ORDER_THREE_BYTES;
  NEXT_COUNTER = new AtomicInteger(secureRandom.nextInt());
  } catch (Exception e) {
  throw new RuntimeException(e);
@@ -443,46 +407,4 @@ private static int hexCharToInt(final char c) {
  private static int dateToTimestampSeconds(final Date time) {
  return (int) (time.getTime() / 1000);
  }
-
- // Big-Endian helpers, in this class because all other BSON numbers are little-endian
-
- private static int makeInt(final byte b3, final byte b2, final byte b1, final byte b0) {
- // CHECKSTYLE:OFF
- return (((b3) << 24) |
- ((b2 & 0xff) << 16) |
- ((b1 & 0xff) << 8) |
- ((b0 & 0xff)));
- // CHECKSTYLE:ON
- }
-
- private static short makeShort(final byte b1, final byte b0) {
- // CHECKSTYLE:OFF
- return (short) (((b1 & 0xff) << 8) | ((b0 & 0xff)));
- // CHECKSTYLE:ON
- }
-
- private static byte int3(final int x) {
- return (byte) (x >> 24);
- }
-
- private static byte int2(final int x) {
- return (byte) (x >> 16);
- }
-
- private static byte int1(final int x) {
- return (byte) (x >> 8);
- }
-
- private static byte int0(final int x) {
- return (byte) (x);
- }
-
- private static byte short1(final short x) {
- return (byte) (x >> 8);
- }
-
- private static byte short0(final short x) {
- return (byte) (x);
- }
-
 }