change uuid to use Random.RandomDevice() instead of Random.default_rn…

…g() (#35872)

Co-authored-by: Rafael Fourquet <fourquet.rafael@gmail.com>

NEWS.md

@@ -74,6 +74,9 @@ Standard library changes
 #### Distributed
 
 
+#### UUIDs
+* Change `uuid1` and `uuid4` to use `Random.RandomDevice()` as default random number generator ([#35872]).
+
 Deprecated or removed
 ---------------------
 

stdlib/UUIDs/src/UUIDs.jl

@@ -36,12 +36,21 @@ const namespace_oid  = UUID(0x6ba7b8129dad11d180b400c04fd430c8) # 6ba7b812-9dad-
 const namespace_x500 = UUID(0x6ba7b8149dad11d180b400c04fd430c8) # 6ba7b814-9dad-11d1-80b4-00c04fd430c8
 
 """
-    uuid1([rng::AbstractRNG=GLOBAL_RNG]) -> UUID
+    uuid1([rng::AbstractRNG]) -> UUID
 
 Generates a version 1 (time-based) universally unique identifier (UUID), as specified
 by RFC 4122. Note that the Node ID is randomly generated (does not identify the host)
 according to section 4.5 of the RFC.
 
+The default rng used by `uuid1` is not `GLOBAL_RNG` and every invocation of `uuid1()` without
+an argument should be expected to return a unique identifier. Importantly, the outputs of
+`uuid1` do not repeat even when `Random.seed!(seed)` is called. Currently (as of Julia 1.6),
+`uuid1` uses `Random.RandomDevice` as the default rng. However, this is an implementation
+detail that may change in the future.
+
+!!! compat "Julia 1.6"
+    The output of `uuid1` does not depend on `GLOBAL_RNG` as of Julia 1.6.
+
 # Examples
 ```jldoctest; filter = r"[a-z0-9]{8}-([a-z0-9]{4}-){3}[a-z0-9]{12}"
 julia> rng = MersenneTwister(1234);
@@ -50,7 +59,7 @@ julia> uuid1(rng)
 UUID("cfc395e8-590f-11e8-1f13-43a2532b2fa8")
 ```
 """
-function uuid1(rng::AbstractRNG=Random.default_rng())
+function uuid1(rng::AbstractRNG=Random.RandomDevice())
     u = rand(rng, UInt128)
 
     # mask off clock sequence and node
@@ -74,11 +83,20 @@ function uuid1(rng::AbstractRNG=Random.default_rng())
 end
 
 """
-    uuid4([rng::AbstractRNG=GLOBAL_RNG]) -> UUID
+    uuid4([rng::AbstractRNG]) -> UUID
 
 Generates a version 4 (random or pseudo-random) universally unique identifier (UUID),
 as specified by RFC 4122.
 
+The default rng used by `uuid4` is not `GLOBAL_RNG` and every invocation of `uuid4()` without
+an argument should be expected to return a unique identifier. Importantly, the outputs of
+`uuid4` do not repeat even when `Random.seed!(seed)` is called. Currently (as of Julia 1.6),
+`uuid4` uses `Random.RandomDevice` as the default rng. However, this is an implementation
+detail that may change in the future.
+
+!!! compat "Julia 1.6"
+    The output of `uuid4` does not depend on `GLOBAL_RNG` as of Julia 1.6.
+
 # Examples
 ```jldoctest
 julia> rng = MersenneTwister(1234);
@@ -87,7 +105,7 @@ julia> uuid4(rng)
 UUID("196f2941-2d58-45ba-9f13-43a2532b2fa8")
 ```
 """
-function uuid4(rng::AbstractRNG=Random.default_rng())
+function uuid4(rng::AbstractRNG=Random.RandomDevice())
     u = rand(rng, UInt128)
     u &= 0xffffffffffff0fff3fffffffffffffff
     u |= 0x00000000000040008000000000000000

stdlib/UUIDs/test/runtests.jl

@@ -54,3 +54,11 @@ for (init_uuid, next_uuid) in standard_namespace_uuids
     result = uuid5(init_uuid, "julia")
     @test next_uuid == result
 end
+
+# Issue 35860
+Random.seed!(Random.GLOBAL_RNG, 10)
+u1 = uuid1()
+u4 = uuid4()
+Random.seed!(Random.GLOBAL_RNG, 10)
+@test u1 != uuid1()
+@test u4 != uuid4()