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change uuid to use Random.RandomDevice() instead of Random.default_rng() #35872

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Merged
merged 11 commits into from
May 27, 2020
+33 −4
Merged

change uuid to use Random.RandomDevice() instead of Random.default_rng() #35872

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6dcace2
change uuid Random.default_rng() => Random.RandomDevice()
ssikdar1 May 13, 2020
63607eb
add regression test
ssikdar1 May 14, 2020
13cbf79
add NEWS entry
ssikdar1 May 14, 2020
3a637b3
update function docstrings
ssikdar1 May 14, 2020
34f29e3
add git add -u! compat message
ssikdar1 May 14, 2020
726b4f4
fix location of compat
ssikdar1 May 14, 2020
507b454
use a default RNG from RandomDevice initialized at startup
ssikdar1 May 16, 2020
ba4c68a
Revert "use a default RNG from RandomDevice initialized at startup"
ssikdar1 May 16, 2020
eb5ddc5
update signature and docstring
ssikdar1 May 24, 2020
1e91639
Update stdlib/UUIDs/src/UUIDs.jl
ssikdar1 May 26, 2020
c70c44a
Update stdlib/UUIDs/src/UUIDs.jl
ssikdar1 May 26, 2020
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6 changes: 4 additions & 2 deletions stdlib/UUIDs/src/UUIDs.jl
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Original file line number Diff line number Diff line change
@@ -35,6 +35,8 @@ const namespace_url = UUID(0x6ba7b8119dad11d180b400c04fd430c8) # 6ba7b811-9dad-
const namespace_oid = UUID(0x6ba7b8129dad11d180b400c04fd430c8) # 6ba7b812-9dad-11d1-80b4-00c04fd430c8
const namespace_x500 = UUID(0x6ba7b8149dad11d180b400c04fd430c8) # 6ba7b814-9dad-11d1-80b4-00c04fd430c8

uuid_rng = Random.RandomDevice()

"""
uuid1([rng::AbstractRNG=Random.RandomDevice()]) -> UUID

@@ -53,7 +55,7 @@ UUID("cfc395e8-590f-11e8-1f13-43a2532b2fa8")
!!! compat "Julia 1.6"
The default rng has been changed to use Random.RandomDevice as of Julia 1.6
"""
function uuid1(rng::AbstractRNG=Random.RandomDevice())
function uuid1(rng::AbstractRNG=uuid_rng)
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Why did you make this change? Creating a new RandomDevice() is extremely cheap on non-Windows, and on Windows having a global uuid_rng is not thread-safe...

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@rfourquet I guess misunderstood @JeffBezanson 's comment above?

How about using a dedicated default RNG for UUIDs that's initialized from RandomDevice at startup?

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My interpretation of it was using an RNG like default_rng() (currently MersenneTwister() which is thread-safely initialized), which is therefore immune against the unqualified Random.seed!() but way faster than RandomDevice(), but "initialized from RandomDevice()" means it's seeded from RandomDevice() at startup.

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But Stefan's last comment suggests to keep it how it was, because the poor performance of RandomDevice might considered as a non-problem until someone complains.

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Okay! I reverted 507b454 . I'll leave it alone for now until there's something I should explicitly add/change/remove.

u = rand(rng, UInt128)

# mask off clock sequence and node
@@ -92,7 +94,7 @@ UUID("196f2941-2d58-45ba-9f13-43a2532b2fa8")
!!! compat "Julia 1.6"
The default rng has been changed to use Random.RandomDevice as of Julia 1.6
"""
function uuid4(rng::AbstractRNG=Random.RandomDevice())
function uuid4(rng::AbstractRNG=uuid_rng)
u = rand(rng, UInt128)
u &= 0xffffffffffff0fff3fffffffffffffff
u |= 0x00000000000040008000000000000000