Environment:
CentOS Linux Release 7.7.1908 (Core)
PHP 7.3.11
UUID Extention 1.0.4
PHP support for UUID feeling does not seem really serious, UUID PECL extension is merely to package libuuid, and not as straightforward to provide a complete realization UUID as other languages. Since libuuid provide only version 1 and version UUID 4, so ...... happy that these two suffice.
uuid_create( [int $uuid_type = UUID_TYPE_DEFAULT] ) : string
$uuid_type
One of the following constants:
UUID_TYPE_DEFAULT // 0
UUID_TYPE_TIME // 1
UUID_TYPE_DCE // 4
UUID_TYPE_NAME // 1
UUID_TYPE_RANDOM // 4
libuuid provides a UUID version 1 and 4 to achieve, but also defines only UUID_TYPE_DCE_TIME and UUID_TYPE_DCE_RANDOM two constants. PHP's UUID extensions, constants are constant mapping libuuid by definition. So, while the extension defines four constants according to UUID standard name, but for the current version of libuuid, it can only be mapped to two constants. UUID_TYPE_TIME mapping the constant libuuid UUID_TYPE_DCE_TIME , UUID corresponding to version 1 implemented; UUID_TYPE_RANDOM mapped to the constant libuuid UUID_TYPE_DCE_RANDOM , corresponding to implement uuid version 4. The UUID_TYPE_DCE and UUID_TYPE_NAME two constants, although it is easy to see from the constant's name corresponds to the UUID version 2 and version 3, 5, but can only be mapped to a constant libuuid of UUID_TYPE_DCE_RANDOM and UUID_TYPE_DCE_TIME , can be used but does not have practical significance.
Constant UUID_TYPE_DEFAULT is the default value, indicating the default selection of libuuid. By default, if the present system is a high-quality random number (such as / dev / urandom or / dev / random available), provides the UUID 4 version, version or UUID 1 is provided. UUID version 1 is generally believed that the probability of duplication of a smaller, almost can guarantee true uniqueness, but considering the MAC leak caused by security concerns, most of the time or tend to use UUID version 4.
return
If the parameters are valid (0,1 or 4), and returns the string UUID.
If the argument can not be identified, throw a warning message and return to the default UUID string.
uuid_is_valid( string $uuid ) ： bool
$uuid
UUID string to be tested.
return
return true or false. $ uuid are not case sensitive.
uuid_compare(string $uuid1, string $uuid2) : int
$uuid1 , $uuid2
UUID string to be compared.
returen
If $ UUID1 or $ UUID2 not valid UUID string, bool return value to false .
If $ UUID1 and $ uui2 not identical: $ UUID1 < $ UUID2 , returns a positive integer; $ UUID1 > $ UUID2 , it returns a negative integer.
If $ UUID1 = $ UUID2 , returns integer value 0.
uuid_is_null(string $uuid) : bool
$uuid
UUID string to be tested.
return
if $ uuid is not a valid UUID string, it returns false .
If $ uuid is not NULL UUID string, it returns false .
If $ uuid is NULL UUID string, returns to true .
UUID NULL
'00000000-0000-0000-0000-000000000000' it is the UUID string 0 is called a NULL UUID (or NIL UUID?).
uuid_type(string $uuid) : int
$uuid
Uuid string to be tested.
return
if $ uuid is not a valid UUID string, the return value bool false .
If $ UUID is NULL UUID, returns the integer value of -1.
If $ UUID is valid UUID string, returns 4 or 5, the corresponding version of the UUID.
uuid_variant(string $uuid) : int
$uuid
UUID string to be tested.
return
if $ UUID is not a valid string UUID, bool return type value to false .
If $ UUID is NULL UUID, returns the integer value of -1.
If $ UUID is valid UUID string, it returns an integer value 0, 1 or 3.
The constant name libuuid defined, it is easy to distinguish the meaning of the return value:
UUID_VARIANT_NCS // 0
UUID_VARIANT_DCE // . 1
UUID_VARIANT_MICROSOFT // 2
UUID_VARIANT_OTHER // . 3
uuid_time(string $uuid) ： int
$uuid
UUID strings to be parsed.
return
if $ UUID is not a valid string UUID, if $ UUID not rfc4122 defined variants (uuid_variant () returns a value of 1, in libuuid predefined constants UUID_VARIANT_DCE ), if $ UUID UUID not the version 1 (based on UUID time), bool value is returned to false .
If $ UUID is defined based on the version of a configuration rfc4122 UUID, it returns an integer value. The UNIX timestamp value is constructed UUID string was used.
uuid_mac(string $uuid) ： string
$uuid
Uuid string to be parsed.
return
if $ UUID is not a valid string UUID, if $ UUID not rfc4122 defined variants (uuid_variant () returns a value of 1, in libuuid predefined constants UUID_VARIANT_DCE ), if $ UUID UUID not the version 1 (based on UUID time), bool value is returned to false .
If configured $ UUID is not a valid MAC address to be used when, bool value is returned to false .
If $ UUID is defined based on the version of a configuration rfc4122 UUID, and configured $ UUID used when a valid MAC address, the MAC address is returned, represented as a string of 12 hexadecimal.
uuid_parse(string $uuid) : string
$uuid
UUID string to be packaged.
return
if $ uuid is not a valid UUID string, the return value bool false .
If $ UUID is valid UUID string, then remove "-" after the package into a 16-bit binary strings of the front and high return. Similar functions in PHP pack ( 'L *') effects.
uuid_unparse(string $uuid) ： string
Function uuid_parse () of the inverse process. If the parameter data is valid, a UUID string is returned, otherwise bool value to false .
OK, that's all. Hope that helps.
Reference:
https://tools.ietf.org/html/rfc4122
https://sourceforge.net/p/libuuid/code/ci/master/tree/