This change adds a code generator tool for creating EncodeRLP method
implementations. The generated methods will behave identically to the
reflect-based encoder, but run faster because there is no reflection overhead.
Package rlp now provides the EncoderBuffer type for incremental encoding. This
is used by generated code, but the new methods can also be useful for
hand-written encoders.
There is also experimental support for generating DecodeRLP, and some new
methods have been added to the existing Stream type to support this. Creating
decoders with rlpgen is not recommended at this time because the generated
methods create very poor error reporting.
More detail about package rlp changes:
* rlp: externalize struct field processing / validation
This adds a new package, rlp/internal/rlpstruct, in preparation for the
RLP encoder generator.
I think the struct field rules are subtle enough to warrant extracting
this into their own package, even though it means that a bunch of
adapter code is needed for converting to/from rlpstruct.Type.
* rlp: add more decoder methods (for rlpgen)
This adds new methods on rlp.Stream:
- Uint64, Uint32, Uint16, Uint8, BigInt
- ReadBytes for decoding into []byte
- MoreDataInList - useful for optional list elements
* rlp: expose encoder buffer (for rlpgen)
This exposes the internal encoder buffer type for use in EncodeRLP
implementations.
The new EncoderBuffer type is a sort-of 'opaque handle' for a pointer to
encBuffer. It is implemented this way to ensure the global encBuffer pool
is handled correctly.
As per benchmark results below, these changes speed up encoding/decoding of
consensus objects a bit.
name old time/op new time/op delta
EncodeRLP/legacy-header-8 384ns ± 1% 331ns ± 3% -13.83% (p=0.000 n=7+8)
EncodeRLP/london-header-8 411ns ± 1% 359ns ± 2% -12.53% (p=0.000 n=8+8)
EncodeRLP/receipt-for-storage-8 251ns ± 0% 239ns ± 0% -4.97% (p=0.000 n=8+8)
EncodeRLP/receipt-full-8 319ns ± 0% 300ns ± 0% -5.89% (p=0.000 n=8+7)
EncodeRLP/legacy-transaction-8 389ns ± 1% 387ns ± 1% ~ (p=0.099 n=8+8)
EncodeRLP/access-transaction-8 607ns ± 0% 581ns ± 0% -4.26% (p=0.000 n=8+8)
EncodeRLP/1559-transaction-8 627ns ± 0% 606ns ± 1% -3.44% (p=0.000 n=8+8)
DecodeRLP/legacy-header-8 831ns ± 1% 813ns ± 1% -2.20% (p=0.000 n=8+8)
DecodeRLP/london-header-8 824ns ± 0% 804ns ± 1% -2.44% (p=0.000 n=8+7)
* rlp: pass length to byteArrayBytes
This makes it possible to inline byteArrayBytes. For arrays, the length is known
at encoder construction time, so the call to v.Len() can be avoided.
* rlp: avoid IsNil for pointer encoding
It's actually cheaper to use Elem first, because it performs less checks
on the value. If the pointer was nil, the result of Elem is 'invalid'.
* rlp: minor optimizations for slice/array encoding
For empty slices/arrays, we can avoid storing a list header entry in the
encoder buffer. Also avoid doing the tail check at encoding time because
it is already known at encoder construction time.
This change grows the static integer buffer in Stream to 32 bytes,
making it possible to decode 256bit integers without allocating a
temporary buffer.
In the recent commit 088da24, Stream struct size decreased from 120
bytes down to 88 bytes. This commit grows the struct to 112 bytes again,
but the size change will not degrade performance because Stream
instances are internally cached in sync.Pool.
name old time/op new time/op delta
DecodeBigInts-8 12.2µs ± 0% 8.6µs ± 4% -29.58% (p=0.000 n=9+10)
name old speed new speed delta
DecodeBigInts-8 230MB/s ± 0% 326MB/s ± 4% +42.04% (p=0.000 n=9+10)
All encoding/decoding operations read the type cache to find the
writer/decoder function responsible for a type. When analyzing CPU
profiles of geth during sync, I found that the use of sync.RWMutex in
cache lookups appears in the profiles. It seems we are running into
CPU cache contention problems when package rlp is heavily used
on all CPU cores during sync.
This change makes it use atomic.Value + a writer lock instead of
sync.RWMutex. In the common case where the typeinfo entry is present in
the cache, we simply fetch the map and lookup the type.
This commit makes various cleanup changes to rlp.Stream.
* rlp: shrink Stream struct
This removes a lot of unused padding space in Stream by reordering the
fields. The size of Stream changes from 120 bytes to 88 bytes. Stream
instances are internally cached and reused using sync.Pool, so this does
not improve performance.
* rlp: simplify list stack
The list stack kept track of the size of the current list context as
well as the current offset into it. The size had to be stored in the
stack in order to subtract it from the remaining bytes of any enclosing
list in ListEnd. It seems that this can be implemented in a simpler
way: just subtract the size from the enclosing list context in List instead.
This adds support for a new struct tag "optional". Using this tag, structs used
for RLP encoding/decoding can be extended in a backwards-compatible way,
by adding new fields at the end.
io.Reader may return n > 0 and io.EOF at the end of the input stream.
readFull did not handle this correctly, looking only at the error. This fixes
it to check for n == len(buf) as well.
* build: use golangci-lint
This changes build/ci.go to download and run golangci-lint instead
of gometalinter.
* core/state: fix unnecessary conversion
* p2p/simulations: fix lock copying (found by go vet)
* signer/core: fix unnecessary conversions
* crypto/ecies: remove unused function cmpPublic
* core/rawdb: remove unused function print
* core/state: remove unused function xTestFuzzCutter
* core/vm: disable TestWriteExpectedValues in a different way
* core/forkid: remove unused function checksum
* les: remove unused type proofsData
* cmd/utils: remove unused functions prefixedNames, prefixFor
* crypto/bn256: run goimports
* p2p/nat: fix goimports lint issue
* cmd/clef: avoid using unkeyed struct fields
* les: cancel context in testRequest
* rlp: delete unreachable code
* core: gofmt
* internal/build: simplify DownloadFile for Go 1.11 compatibility
* build: remove go test --short flag
* .travis.yml: disable build cache
* whisper/whisperv6: fix ineffectual assignment in TestWhisperIdentityManagement
* .golangci.yml: enable goconst and ineffassign linters
* build: print message when there are no lint issues
* internal/build: refactor download a bit
* rlp: improve nil pointer handling
In both encoder and decoder, the rules for encoding nil pointers were a
bit hard to understand, and didn't leave much choice. Since RLP allows
two empty values (empty list, empty string), any protocol built on RLP
must choose either of these values to represent the null value in a
certain context.
This change adds choice in the form of two new struct tags, "nilString"
and "nilList". These can be used to specify how a nil pointer value is
encoded. The "nil" tag still exists, but its implementation is now
explicit and defines exactly how nil pointers are handled in a single
place.
Another important change in this commit is how nil pointers and the
Encoder interface interact. The EncodeRLP method was previously called
even on nil values, which was supposed to give users a choice of how
their value would be handled when nil. It turns out this is a stupid
idea. If you create a network protocol containing an object defined in
another package, it's better to be able to say that the object should be
a list or string when nil in the definition of the protocol message
rather than defining the encoding of nil on the object itself.
As of this commit, the encoding rules for pointers now take precedence
over the Encoder interface rule. I think the "nil" tag will work fine
for most cases. For special kinds of objects which are a struct in Go
but strings in RLP, code using the object can specify the desired
encoding of nil using the "nilString" and "nilList" tags.
* rlp: propagate struct field type errors
If a struct contained fields of undecodable type, the encoder and
decoder would panic instead of returning an error. Fix this by
propagating type errors in makeStruct{Writer,Decoder} and add a test.
These changes fix two corner cases related to internal handling of types
in package rlp: The "tail" struct tag can only be applied to the last field.
The check for this was wrong and didn't allow for private fields after the
field with the tag. Unsupported types (e.g. structs containing int) which
implement either the Encoder or Decoder interface but not both
couldn't be encoded/decoded.
Also fixes#19367
Decoding did not reject byte arrays of length one with a single element
b where 55 < b < 128. Such byte arrays must be rejected because
they must be encoded as the single byte b instead.
The list size checking overflowed if the size information
for a value was bigger than the list. This is resolved by
always performing the check before reading.
The rules have changed as follows:
* When decoding into pointers, empty values no longer produce
a nil pointer. This can be overriden for struct fields using the
struct tag "nil".
* When decoding into structs, the input list must contain an element
for each field.
All integers (including size information in type tags) need to be
encoded using the smallest possible encoding. This commit expands the
stricter validation introduced for *big.Int in commit 59597d23a5ee268
to all integer types and size tags.
A single zero byte carries information and should not set the pointer
to nil. This is arguably a corner case. While here, fix the comment
to explain pointer reuse.
This is a preliminary fix for #420 (SEC-18 RLP decoder unsafe
allocation). If a sane input limit is set on the rlp.Stream,
it should no longer be possible to cause huge []byte allocations.
This needs to be supported because []someInterface does occur sometimes.
Funny enough, the fix involves changes to the decoder. makeDecoder
cannot return an error for non-empty interfaces anymore because the type
cache builds both decoder and writer. Do the check at 'runtime' instead.
I'm reasonably confident that the encoding matches the output of
ethutil.Encode for values that it supports. Some of the tests have been
adpated from the Ethereum testing repository.
There are still TODOs in the code.
