[JAVA-586] ObjectId MachineId uses network interface names instead of mac address or something more unique Created: 08/Jun/12  Updated: 31/Mar/15  Resolved: 25/Jun/13

Status: Closed
Project: Java Driver
Component/s: Codecs
Affects Version/s: 2.7.2
Fix Version/s: 3.0.0

Type: Bug Priority: Minor - P4
Reporter: Wes Freeman Assignee: Jeffrey Yemin
Resolution: Done Votes: 1
Labels: None
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified
Environment:

Affects all environments AFAIK, although I only tested on OSX 10.7.3



 Description   

The 3 byte hash of the machine id should be based on something more unique than the network interface names (ie. "en1" or "eth0").



 Comments   
Comment by Jeffrey Yemin [ 31/Mar/15 ]

Closing all resolved 3.0.0 issues, as 3.0.0 has been tagged and released.

Comment by Ivan Todoroski [ 13/Sep/14 ]

Hello Jeff,

I appreciate the solution for 3.x, but that release seems a long way off (this ticket was assigned to 3.x almost 2 years ago) and besides, not everyone might be able to upgrade to 3.x immediately.

Why not just use reflection in the 2.x driver to get the same functionality? You can check if the method getHardwareAddress() exists and call it reflectively if it does, otherwise fall back on toString().

That way if the 2.x driver is running inside a Java 6+ VM we get to benefit from improved uniqueness of ObjectId, while if it's running on Java 5 it will still be backward compatible, it will just use toString() like it does now.

I realize that reflection should be avoided in general, but we're talking about a static initializer here that only gets called once on startup, so performance is not an issue, and the practical advantages in this case should outweigh the general distaste for reflection.

Comment by auto [ 30/May/13 ]

Author:

{u'username': u'jyemin', u'name': u'Jeff Yemin', u'email': u'jeff.yemin@10gen.com'}

Message: JAVA-609, JAVA-586, JAVA-749: Major changes to ObjectId class. The major change is that ObjectId now conforms to the spec. Instead of representing as 3 4-byte value, it now properly uses a 4-byte timestamp, 3-byte machine identifier, 2-byte process identifier, and 3-byte counter.

The logic for generating machine identifier has changed. Since we are java 6 minimum now, using NetworkInterface.getHardwareAddress() for more uniqueness.

The logic for generating process identifier has changed. It attempts to get the actual numeric process id from JMX, falling back to a string hash only if if it can't. It looks for a pattern in the process name of <process_id>@<host_name>. No longer using the classloader hash either, since each class loader will have a separate instance of NEXT_COUNTER, which is seeded with a random number and so is very unlikely to clash.

Removed a bunch of stuff

Removed support for 'babble' format.
Removed constructors that didn't conform to the spec (machine identifier only, instead of machine identifer and process identifier)
Removed support for isNew/notNew. I don't see a need for this. It was only used in save method, and it seems the only purpose is to decide whether to do an insert of an upsert. I don't see any harm in always doing an upsert. This also has
the nice property of making ObjectId immutable.
Removed a bunch of poorly named methods: _flip(int), _inc(), _machine(), _time()
Removed massageToObjectId(java.lang.Object)' factory method

Other non-backwards compatible changes:

equals method will no longer compare equal to anything but an ObjectId

Additionally, added getters that conform to the spec: timestamp, machineIdentifier, processIdentifier, and counter. Deprecated the old ones.
Branch: 3.0.x
https://github.com/mongodb/mongo-java-driver/commit/aa4b4355c808e045ce00cc1dfbdd0bf78fb6901a

Comment by Jeffrey Yemin [ 30/Dec/12 ]

Moving to 3.0, where we can consider abandoning Java 5.

See https://github.com/mongodb/mongo-java-driver/pull/76 for an implementation which uses a method added in Java 6.

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