xenial (3) oid.3.gz

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.