NAME

       ObjectIDs - None

COMPOSITION

       \[bu]
         4 bytes : The UNIX timestamp in big‐endian format.

       \[bu]
         3 bytes : The first 3 bytes of MD5(hostname) \&.

       \[bu]
         2 bytes : The pid_t of the current process. Alternatively the task‐id if configured.

       \[bu]
         3 bytes : A 24‐bit monotonic counter incrementing from rand(3) in big‐endian.

SORTING OBJECTIDS

       The  typical  way  to  sort  in C is using qsort(3) \&. Therefore, Libbson provides a qsort(3) compatible
       callback function named bson_oid_compare(3) \&. It returns less than 1 , greater than 1 , or 0  depending
       on the equality of two bson_oid_t structures.

COMPARING OBJECT IDS

       If you simply want to compare two bson_oid_t structures for equality, use bson_oid_equal(3) \&.

GENERATING

       To generate a bson_oid_t , you may use the following.

PARSING OBJECTID STRINGS

       You can also parse a string contianing a bson_oid_t \&. The input string MUST be 24 characters or more in
       length.

       If  you  need  to  parse  may  bson_oid_t  in  a tight loop and can guarantee the data is safe, you might
       consider using the inline variant. It will be inlined into your code and reduce the need  for  a  foreign
       function call.

HASHING OBJECTIDS

       If  you  need  to  store  items  in  a  hashtable, you may want to use the bson_oid_t as the key. Libbson
       provides a hash function for just this purpose. It is based on DJB hash.

FETCHING OBJECTID CREATION TIME

       You can easily fetch the time that a bson_oid_t was generated using bson_oid_get_time_t(3) \&.

COLOPHON

       This page is part of libbson.  Please report any bugs at https://jira.mongodb.org/browse/CDRIVER.

libbson                                            2016‐01‐18                                       OBJECTIDS(3)