Providing a hash.Block512 is an implementation detail of how deephash
works today, but providing an opaque type with mostly equivalent API
(i.e., HashUint8, HashBytes, etc. methods) is still sensible.
Thus, define a public Hasher type that exposes exactly the API
that an implementation of SelfHasher would want to call.
This gives us freedom to change the hashing algorithm of deephash
at some point in the future.
Also, this type is likely going to be called by types that are
going to memoize their own hash results, we additionally add
a HashSum method to simplify this use case.
Add documentation to SelfHasher on how a type might implement it.
Updates: corp#16409
Signed-off-by: Joe Tsai <joetsai@digital-static.net>
Run `staticcheck` with `U1000` to find unused code. This cleans up about
a half of it. I'll do the other half separately to keep PRs manageable.
Updates #cleanup
Signed-off-by: Andrew Lytvynov <awly@tailscale.com>
I'd added a test case of deephash against a tailcfg.Node to make sure
it worked at all more than anything. We don't care what the exact
bytes are in this test, just that it doesn't fail. So adjust for that.
Then when we make changes to tailcfg.Node and types under it, we don't
need to keep adjusting this test.
Updates #cleanup
Change-Id: Ibf4fa42820aeab8f5292fe65f9f92ffdb0b4407b
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
Define PeerCapabilty and PeerCapMap as the new way of sending down
inter-peer capability information.
Previously, this was unstructured and you could only send down strings
which got too limiting for certain usecases. Instead add the ability
to send down raw JSON messages that are opaque to Tailscale but provide
the applications to define them however they wish.
Also update accessors to use the new values.
Updates #4217
Signed-off-by: Maisem Ali <maisem@tailscale.com>
The server hasn't sent it in ages.
Updates #cleanup
Change-Id: I9695ab0f074ec6fb006e11faf3cdfc5ca049fbf8
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
This makes `omitempty` actually work, and saves bytes in each map response.
Updates tailscale/corp#8020
Signed-off-by: Maisem Ali <maisem@tailscale.com>
A peer can have IsWireGuardOnly, which means it will not support DERP or
Disco, and it must have Endpoints filled in order to be usable.
In the present implementation only the first Endpoint will be used as
the bestAddr.
Updates tailscale/corp#10351
Co-authored-by: Charlotte Brandhorst-Satzkorn <charlotte@tailscale.com>
Co-authored-by: James Tucker <james@tailscale.com>
Signed-off-by: James Tucker <james@tailscale.com>
This only adds the field, to be used in a future commit.
Updates tailscale/corp#8020
Co-authored-by: Melanie Warrick <warrick@tailscale.com>
Signed-off-by: Maisem Ali <maisem@tailscale.com>
This updates all source files to use a new standard header for copyright
and license declaration. Notably, copyright no longer includes a date,
and we now use the standard SPDX-License-Identifier header.
This commit was done almost entirely mechanically with perl, and then
some minimal manual fixes.
Updates #6865
Signed-off-by: Will Norris <will@tailscale.com>
Nodes that are expired, taking into account the time delta calculated
from MapResponse.ControlTime have the newly-added Expired boolean set.
For additional defense-in-depth, also replicate what control does and
clear the Endpoints and DERP fields, and additionally set the node key
to a bogus value.
Updates #6932
Signed-off-by: Andrew Dunham <andrew@du.nham.ca>
Change-Id: Ia2bd6b56064416feee28aef5699ca7090940662a
We're adding two log IDs to facilitate data-plane audit logging: a node-specific
log ID, and a domain-specific log ID.
Updated util/deephash/deephash_test.go with revised expectations for tailcfg.Node.
Updates https://github.com/tailscale/corp/issues/6991
Signed-off-by: Aaron Klotz <aaron@tailscale.com>
It is unclear whether the lack of checking nil-ness of slices
was an oversight or a deliberate feature.
Lacking a comment, the assumption is that this was an oversight.
Also, expand the logic to perform cycle detection for recursive slices.
We do this on a per-element basis since a slice is semantically
equivalent to a list of pointers.
Signed-off-by: Joe Tsai <joetsai@digital-static.net>
Add a new lookupTypeHasher function that is just a cached front-end
around the makeTypeHasher function.
We do not need to worry about the recursive type cycle issue that
made getTypeInfo more complicated since makeTypeHasher
is not directly recursive. All calls to itself happen lazily
through a sync.Once upon first use.
Signed-off-by: Joe Tsai <joetsai@digital-static.net>
The entry logic of Hash has extra complexity to make sure
we always have an addressable value on hand.
If not, we heap allocate the input.
For this reason we document that there are performance benefits
to always providing a pointer.
Rather than documenting this, just enforce it through generics.
Also, delete the unused HasherForType function.
It's an interesting use of generics, but not well tested.
We can resurrect it from code history if there's a need for it.
Signed-off-by: Joe Tsai <joetsai@digital-static.net>
This helps pprof better identify which Go kinds take the most time
since the kind is always in the function name.
Signed-off-by: Joe Tsai <joetsai@digital-static.net>
This helps pprof better identify which Go kinds take the most time
since the kind is always in the function name.
There is a minor adjustment where we hash the length of the map
to be more on the cautious side.
Signed-off-by: Joe Tsai <joetsai@digital-static.net>
Rather than having two copies []fieldInfo,
just maintain one and perform merging in the same pass.
Signed-off-by: Joe Tsai <joetsai@digital-static.net>
This helps pprof better identify which Go kinds take the most time
since the kind is always in the function name.
Signed-off-by: Joe Tsai <joetsai@digital-static.net>
Use of reflect.Value.SetXXX panics if the provided argument was
obtained from an unexported struct field.
Instead, pass an unsafe.Pointer around and convert to a
reflect.Value when necessary (i.e., for maps and interfaces).
Converting from unsafe.Pointer to reflect.Value guarantees that
none of the read-only bits will be populated.
When running in race mode, we attach type information to the pointer
so that we can type check every pointer operation.
This also type-checks that direct memory hashing is within
the valid range of a struct value.
We add test cases that previously caused deephash to panic,
but now pass.
Performance:
name old time/op new time/op delta
Hash 14.1µs ± 1% 14.1µs ± 1% ~ (p=0.590 n=10+9)
HashPacketFilter 2.53µs ± 2% 2.44µs ± 1% -3.79% (p=0.000 n=9+10)
TailcfgNode 1.45µs ± 1% 1.43µs ± 0% -1.36% (p=0.000 n=9+9)
HashArray 318ns ± 2% 318ns ± 2% ~ (p=0.541 n=10+10)
HashMapAcyclic 32.9µs ± 1% 31.6µs ± 1% -4.16% (p=0.000 n=10+9)
There is a slight performance gain due to the use of unsafe.Pointer
over reflect.Value methods. Also, passing an unsafe.Pointer (1 word)
on the stack is cheaper than passing a reflect.Value (3 words).
Performance gains are diminishing since SHA-256 hashing now dominates the runtime.
Signed-off-by: Joe Tsai <joetsai@digital-static.net>
When built with "deephash_debug", print the set of HashXXX methods.
Example usage:
$ go test -run=GetTypeHasher/string_slice -tags=deephash_debug
U64(2)+U64(3)+S("foo")+U64(3)+S("bar")+FIN
Signed-off-by: Joe Tsai <joetsai@digital-static.net>
Rather than separate functions to hash each kind,
just rely on the fact that these are direct memory hashable,
thus simplifying the code.
Signed-off-by: Joe Tsai <joetsai@digital-static.net>
Every implementation of typeHasherFunc always returns true,
which implies that the slow path is no longer executed.
Delete it.
h.hashValueWithType(v, ti, ...) is deleted as it is equivalent to:
ti.hasher()(h, v)
h.hashValue(v, ...) is deleted as it is equivalent to:
ti := getTypeInfo(v.Type())
ti.hasher()(h, v)
Signed-off-by: Joe Tsai <joetsai@digital-static.net>
Add support for maps and interfaces to the fast path.
Add cycle-detection to the pointer handling logic.
This logic is mostly copied from the slow path.
A future commit will delete the slow path once
the fast path never falls back to the slow path.
Performance:
name old time/op new time/op delta
Hash-24 18.5µs ± 1% 14.9µs ± 2% -19.52% (p=0.000 n=10+10)
HashPacketFilter-24 2.54µs ± 1% 2.60µs ± 1% +2.19% (p=0.000 n=10+10)
HashMapAcyclic-24 31.6µs ± 1% 30.5µs ± 1% -3.42% (p=0.000 n=9+8)
TailcfgNode-24 1.44µs ± 2% 1.43µs ± 1% ~ (p=0.171 n=10+10)
HashArray-24 324ns ± 1% 324ns ± 2% ~ (p=0.425 n=9+9)
The additional cycle detection logic doesn't incur much slow down
since it only activates if a type is recursive, which does not apply
for any of the types that we care about.
There is a notable performance boost since we switch from the fath path
to the slow path less often. Most notably, a struct with a field that
could not be handled by the fast path would previously cause
the entire struct to go through the slow path.
Signed-off-by: Joe Tsai <joetsai@digital-static.net>
There are 5 types that we care about that implement AppendTo:
key.DiscoPublic
key.NodePublic
netip.Prefix
netipx.IPRange
netip.Addr
The key types are thin wrappers around [32]byte and are memory hashable.
The netip.Prefix and netipx.IPRange types are thin wrappers over netip.Addr
and are hashable by default if netip.Addr is hashable.
The netip.Addr type is the only one with a complex structure where
the default behavior of deephash does not hash it correctly due to the presence
of the intern.Value type.
Drop support for AppendTo and instead add specialized hashing for netip.Addr
that would be semantically equivalent to == on the netip.Addr values.
The AppendTo support was already broken prior to this change.
It was fully removed (intentionally or not) in #4870.
It was partially restored in #4858 for the fast path,
but still broken in the slow path.
Just drop support for it altogether.
This does mean we lack any ability for types to self-hash themselves.
In the future we can add support for types that implement:
interface { DeepHash() Sum }
Test and fuzz cases were added for the relevant types that
used to rely on the AppendTo method.
FuzzAddr has been executed on 1 billion samples without issues.
Signed-off-by: Joe Tsai joetsai@digital-static.net
Rename Hash as Block512 to indicate that this is a general-purpose
hash.Hash for any algorithm that operates on 512-bit block sizes.
While we rename the package as hashx in this commit,
a subsequent commit will move the sha256x package to hashx.
This is done separately to avoid confusing git.
Signed-off-by: Joe Tsai <joetsai@digital-static.net>
Also, rename canMemHash to typeIsMemHashable to be consistent.
There are zero changes to the semantics.
Signed-off-by: Joe Tsai <joetsai@digital-static.net>
Any type that is memory hashable must not be recursive since
there are definitely no pointers involved to make a cycle.
Signed-off-by: Joe Tsai <joetsai@digital-static.net>
Put the t.Size() == 0 check first since this is applicable in all cases.
Drop the last struct field conditional since this is covered by the
sumFieldSize check at the end.
Signed-off-by: Joe Tsai <joetsai@digital-static.net>
Hashing []any is slow since hashing of interfaces is slow.
Hashing of interfaces is slow since we pessimistically assume
that cycles can occur through them and start cycle tracking.
Drop the variadic signature of Update and fix callers to pass in
an anonymous struct so that we are hashing concrete types
near the root of the value tree.
Signed-off-by: Joe Tsai <joetsai@digital-static.net>
Signed-off-by: Joe Tsai <joetsai@digital-static.net>
Formatting a time.Time as RFC3339 is slow.
See https://go.dev/issue/54093
Now that we have efficient hashing of fixed-width integers,
just hash the time.Time as a binary value.
Performance:
Hash-24 19.0µs ± 1% 18.6µs ± 1% -2.03% (p=0.000 n=10+9)
TailcfgNode-24 1.79µs ± 1% 1.40µs ± 1% -21.74% (p=0.000 n=10+9)
Signed-off-by: Joe Tsai <joetsai@digital-static.net>
Switch deephash to use sha256x.Hash.
We add sha256x.HashString to efficiently hash a string.
It uses unsafe under the hood to convert a string to a []byte.
We also modify sha256x.Hash to export the underlying hash.Hash
for testing purposes so that we can intercept all hash.Hash calls.
Performance:
name old time/op new time/op delta
Hash-24 19.8µs ± 1% 19.2µs ± 1% -3.01% (p=0.000 n=10+10)
HashPacketFilter-24 2.61µs ± 0% 2.53µs ± 1% -3.01% (p=0.000 n=8+10)
HashMapAcyclic-24 31.3µs ± 1% 29.8µs ± 0% -4.80% (p=0.000 n=10+9)
TailcfgNode-24 1.83µs ± 1% 1.82µs ± 2% ~ (p=0.305 n=10+10)
HashArray-24 344ns ± 2% 323ns ± 1% -6.02% (p=0.000 n=9+10)
The performance gains is not as dramatic as sha256x over sha256 due to:
1. most of the hashing already occurring through the direct memory hashing logic, and
2. what does not go through direct memory hashing is slowed down by reflect.
Signed-off-by: Joe Tsai <joetsai@digital-static.net>
In Go 1.19, the reflect.Value.MapRange method uses "function outlining"
so that the allocation of reflect.MapIter is inlinable by the caller.
If the iterator doesn't escape the caller, it can be stack allocated.
See https://go.dev/cl/400675
Performance:
name old time/op new time/op delta
HashMapAcyclic-24 31.9µs ± 2% 32.1µs ± 1% ~ (p=0.075 n=10+10)
name old alloc/op new alloc/op delta
HashMapAcyclic-24 0.00B 0.00B ~ (all equal)
Signed-off-by: Joe Tsai <joetsai@digital-static.net>
The logic of deephash is both simpler and easier to reason about
if values are always addressable.
In Go, the composite kinds are slices, arrays, maps, structs,
interfaces, pointers, channels, and functions,
where we define "composite" as a Go value that encapsulates
some other Go value (e.g., a map is a collection of key-value entries).
In the cases of pointers and slices, the sub-values are always addressable.
In the cases of arrays and structs, the sub-values are always addressable
if and only if the parent value is addressable.
In the case of maps and interfaces, the sub-values are never addressable.
To make them addressable, we need to copy them onto the heap.
For the purposes of deephash, we do not care about channels and functions.
For all non-composite kinds (e.g., strings and ints), they are only addressable
if obtained from one of the composite kinds that produce addressable values
(i.e., pointers, slices, addressable arrays, and addressable structs).
A non-addressible, non-composite kind can be made addressable by
allocating it on the heap, obtaining a pointer to it, and dereferencing it.
Thus, if we can ensure that values are addressable at the entry points,
and shallow copy sub-values whenever we encounter an interface or map,
then we can ensure that all values are always addressable and
assume such property throughout all the logic.
Performance:
name old time/op new time/op delta
Hash-24 21.5µs ± 1% 19.7µs ± 1% -8.29% (p=0.000 n=9+9)
HashPacketFilter-24 2.61µs ± 1% 2.62µs ± 0% +0.29% (p=0.037 n=10+9)
HashMapAcyclic-24 30.8µs ± 1% 30.9µs ± 1% ~ (p=0.400 n=9+10)
TailcfgNode-24 1.84µs ± 1% 1.84µs ± 2% ~ (p=0.928 n=10+10)
HashArray-24 324ns ± 2% 332ns ± 2% +2.45% (p=0.000 n=10+10)
Signed-off-by: Joe Tsai <joetsai@digital-static.net>
Brad Fitzpatrick
Joe Tsai
Tom DNetto
Andrew Lytvynov
Maisem Ali
Charlotte Brandhorst-Satzkorn
Will Norris
Andrew Dunham
Josh Soref
Andrew Dunham
Aaron Klotz