Merge pull request #1757 from tendermint/bucky/update-spec
docs/spec: some organizational cleanup
This commit is contained in:
commit
9bad770f21
|
@ -3,7 +3,7 @@ version: 2
|
|||
defaults: &defaults
|
||||
working_directory: /go/src/github.com/tendermint/tendermint
|
||||
docker:
|
||||
- image: circleci/golang:1.10.0
|
||||
- image: circleci/golang:1.10.3
|
||||
environment:
|
||||
GOBIN: /tmp/workspace/bin
|
||||
|
||||
|
|
|
@ -1,4 +1,4 @@
|
|||
# CODEOWNERS: https://help.github.com/articles/about-codeowners/
|
||||
|
||||
# Everything goes through Bucky and Anton. For now.
|
||||
* @ebuchman @melekes
|
||||
# Everything goes through Bucky, Anton, Alex. For now.
|
||||
* @ebuchman @melekes @xla
|
||||
|
|
|
@ -20,7 +20,9 @@ please submit them to our [bug bounty](https://tendermint.com/security)!
|
|||
|
||||
### Consensus Protocol
|
||||
|
||||
- TODO
|
||||
- [Consensus Algorithm](/docs/spec/consensus/consensus.md)
|
||||
- [Time](/docs/spec/consensus/bft-time.md)
|
||||
- [Light-Client](/docs/spec/consensus/light-client.md)
|
||||
|
||||
### P2P and Network Protocols
|
||||
|
||||
|
@ -31,9 +33,12 @@ please submit them to our [bug bounty](https://tendermint.com/security)!
|
|||
- [Mempool](https://github.com/tendermint/tendermint/tree/master/docs/spec/reactors/mempool): gossip transactions so they get included in blocks
|
||||
- Evidence: TODO
|
||||
|
||||
### More
|
||||
- Light Client: TODO
|
||||
- Persistence: TODO
|
||||
### Software
|
||||
|
||||
- [ABCI](/docs/spec/software/abci.md): Details about interactions between the
|
||||
application and consensus engine over ABCI
|
||||
- [Write-Ahead Log](/docs/spec/software/wal.md): Details about how the consensus
|
||||
engine preserves data and recovers from crash failures
|
||||
|
||||
## Overview
|
||||
|
||||
|
@ -42,10 +47,9 @@ hash-linked batches of transactions. Such transaction batches are called "blocks
|
|||
Hence, Tendermint defines a "blockchain".
|
||||
|
||||
Each block in Tendermint has a unique index - its Height.
|
||||
A block at `Height == H` can only be committed *after* the
|
||||
block at `Height == H-1`.
|
||||
Height's in the blockchain are monotonic.
|
||||
Each block is committed by a known set of weighted Validators.
|
||||
Membership and weighting within this set may change over time.
|
||||
Membership and weighting within this validator set may change over time.
|
||||
Tendermint guarantees the safety and liveness of the blockchain
|
||||
so long as less than 1/3 of the total weight of the Validator set
|
||||
is malicious or faulty.
|
||||
|
|
|
@ -372,16 +372,23 @@ against the given signature and message bytes.
|
|||
|
||||
## Evidence
|
||||
|
||||
TODO
|
||||
There is currently only one kind of evidence:
|
||||
|
||||
```
|
||||
TODO
|
||||
// amino: "tendermint/DuplicateVoteEvidence"
|
||||
type DuplicateVoteEvidence struct {
|
||||
PubKey crypto.PubKey
|
||||
VoteA *Vote
|
||||
VoteB *Vote
|
||||
}
|
||||
```
|
||||
|
||||
Every piece of evidence contains two conflicting votes from a single validator that
|
||||
was active at the height indicated in the votes.
|
||||
The votes must not be too old.
|
||||
DuplicateVoteEvidence `ev` is valid if
|
||||
|
||||
- `ev.VoteA` and `ev.VoteB` can be verified with `ev.PubKey`
|
||||
- `ev.VoteA` and `ev.VoteB` have the same `Height, Round, Address, Index, Type`
|
||||
- `ev.VoteA.BlockID != ev.VoteB.BlockID`
|
||||
- `(block.Height - ev.VoteA.Height) < MAX_EVIDENCE_AGE`
|
||||
|
||||
# Execution
|
||||
|
||||
|
|
|
@ -1,246 +0,0 @@
|
|||
# Tendermint Encoding (Pre-Amino)
|
||||
|
||||
## PubKeys and Addresses
|
||||
|
||||
PubKeys are prefixed with a type-byte, followed by the raw bytes of the public
|
||||
key.
|
||||
|
||||
Two keys are supported with the following type bytes:
|
||||
|
||||
```
|
||||
TypeByteEd25519 = 0x1
|
||||
TypeByteSecp256k1 = 0x2
|
||||
```
|
||||
|
||||
```
|
||||
// TypeByte: 0x1
|
||||
type PubKeyEd25519 [32]byte
|
||||
|
||||
func (pub PubKeyEd25519) Encode() []byte {
|
||||
return 0x1 | pub
|
||||
}
|
||||
|
||||
func (pub PubKeyEd25519) Address() []byte {
|
||||
// NOTE: the length (0x0120) is also included
|
||||
return RIPEMD160(0x1 | 0x0120 | pub)
|
||||
}
|
||||
|
||||
// TypeByte: 0x2
|
||||
// NOTE: OpenSSL compressed pubkey (x-cord with 0x2 or 0x3)
|
||||
type PubKeySecp256k1 [33]byte
|
||||
|
||||
func (pub PubKeySecp256k1) Encode() []byte {
|
||||
return 0x2 | pub
|
||||
}
|
||||
|
||||
func (pub PubKeySecp256k1) Address() []byte {
|
||||
return RIPEMD160(SHA256(pub))
|
||||
}
|
||||
```
|
||||
|
||||
See https://github.com/tendermint/go-crypto/blob/v0.5.0/pub_key.go for more.
|
||||
|
||||
## Binary Serialization (go-wire)
|
||||
|
||||
Tendermint aims to encode data structures in a manner similar to how the corresponding Go structs
|
||||
are laid out in memory.
|
||||
Variable length items are length-prefixed.
|
||||
While the encoding was inspired by Go, it is easily implemented in other languages as well, given its intuitive design.
|
||||
|
||||
XXX: This is changing to use real varints and 4-byte-prefixes.
|
||||
See https://github.com/tendermint/go-wire/tree/sdk2.
|
||||
|
||||
### Fixed Length Integers
|
||||
|
||||
Fixed length integers are encoded in Big-Endian using the specified number of bytes.
|
||||
So `uint8` and `int8` use one byte, `uint16` and `int16` use two bytes,
|
||||
`uint32` and `int32` use 3 bytes, and `uint64` and `int64` use 4 bytes.
|
||||
|
||||
Negative integers are encoded via twos-complement.
|
||||
|
||||
Examples:
|
||||
|
||||
```go
|
||||
encode(uint8(6)) == [0x06]
|
||||
encode(uint32(6)) == [0x00, 0x00, 0x00, 0x06]
|
||||
|
||||
encode(int8(-6)) == [0xFA]
|
||||
encode(int32(-6)) == [0xFF, 0xFF, 0xFF, 0xFA]
|
||||
```
|
||||
|
||||
### Variable Length Integers
|
||||
|
||||
Variable length integers are encoded as length-prefixed Big-Endian integers.
|
||||
The length-prefix consists of a single byte and corresponds to the length of the encoded integer.
|
||||
|
||||
Negative integers are encoded by flipping the leading bit of the length-prefix to a `1`.
|
||||
|
||||
Zero is encoded as `0x00`. It is not length-prefixed.
|
||||
|
||||
Examples:
|
||||
|
||||
```go
|
||||
encode(uint(6)) == [0x01, 0x06]
|
||||
encode(uint(70000)) == [0x03, 0x01, 0x11, 0x70]
|
||||
|
||||
encode(int(-6)) == [0xF1, 0x06]
|
||||
encode(int(-70000)) == [0xF3, 0x01, 0x11, 0x70]
|
||||
|
||||
encode(int(0)) == [0x00]
|
||||
```
|
||||
|
||||
### Strings
|
||||
|
||||
An encoded string is length-prefixed followed by the underlying bytes of the string.
|
||||
The length-prefix is itself encoded as an `int`.
|
||||
|
||||
The empty string is encoded as `0x00`. It is not length-prefixed.
|
||||
|
||||
Examples:
|
||||
|
||||
```go
|
||||
encode("") == [0x00]
|
||||
encode("a") == [0x01, 0x01, 0x61]
|
||||
encode("hello") == [0x01, 0x05, 0x68, 0x65, 0x6C, 0x6C, 0x6F]
|
||||
encode("¥") == [0x01, 0x02, 0xC2, 0xA5]
|
||||
```
|
||||
|
||||
### Arrays (fixed length)
|
||||
|
||||
An encoded fix-lengthed array is the concatenation of the encoding of its elements.
|
||||
There is no length-prefix.
|
||||
|
||||
Examples:
|
||||
|
||||
```go
|
||||
encode([4]int8{1, 2, 3, 4}) == [0x01, 0x02, 0x03, 0x04]
|
||||
encode([4]int16{1, 2, 3, 4}) == [0x00, 0x01, 0x00, 0x02, 0x00, 0x03, 0x00, 0x04]
|
||||
encode([4]int{1, 2, 3, 4}) == [0x01, 0x01, 0x01, 0x02, 0x01, 0x03, 0x01, 0x04]
|
||||
encode([2]string{"abc", "efg"}) == [0x01, 0x03, 0x61, 0x62, 0x63, 0x01, 0x03, 0x65, 0x66, 0x67]
|
||||
```
|
||||
|
||||
### Slices (variable length)
|
||||
|
||||
An encoded variable-length array is length-prefixed followed by the concatenation of the encoding of
|
||||
its elements.
|
||||
The length-prefix is itself encoded as an `int`.
|
||||
|
||||
An empty slice is encoded as `0x00`. It is not length-prefixed.
|
||||
|
||||
Examples:
|
||||
|
||||
```go
|
||||
encode([]int8{}) == [0x00]
|
||||
encode([]int8{1, 2, 3, 4}) == [0x01, 0x04, 0x01, 0x02, 0x03, 0x04]
|
||||
encode([]int16{1, 2, 3, 4}) == [0x01, 0x04, 0x00, 0x01, 0x00, 0x02, 0x00, 0x03, 0x00, 0x04]
|
||||
encode([]int{1, 2, 3, 4}) == [0x01, 0x04, 0x01, 0x01, 0x01, 0x02, 0x01, 0x03, 0x01, 0x4]
|
||||
encode([]string{"abc", "efg"}) == [0x01, 0x02, 0x01, 0x03, 0x61, 0x62, 0x63, 0x01, 0x03, 0x65, 0x66, 0x67]
|
||||
```
|
||||
|
||||
### BitArray
|
||||
|
||||
BitArray is encoded as an `int` of the number of bits, and with an array of `uint64` to encode
|
||||
value of each array element.
|
||||
|
||||
```go
|
||||
type BitArray struct {
|
||||
Bits int
|
||||
Elems []uint64
|
||||
}
|
||||
```
|
||||
|
||||
### Time
|
||||
|
||||
Time is encoded as an `int64` of the number of nanoseconds since January 1, 1970,
|
||||
rounded to the nearest millisecond.
|
||||
|
||||
Times before then are invalid.
|
||||
|
||||
Examples:
|
||||
|
||||
```go
|
||||
encode(time.Time("Jan 1 00:00:00 UTC 1970")) == [0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00]
|
||||
encode(time.Time("Jan 1 00:00:01 UTC 1970")) == [0x00, 0x00, 0x00, 0x00, 0x3B, 0x9A, 0xCA, 0x00] // 1,000,000,000 ns
|
||||
encode(time.Time("Mon Jan 2 15:04:05 -0700 MST 2006")) == [0x0F, 0xC4, 0xBB, 0xC1, 0x53, 0x03, 0x12, 0x00]
|
||||
```
|
||||
|
||||
### Structs
|
||||
|
||||
An encoded struct is the concatenation of the encoding of its elements.
|
||||
There is no length-prefix.
|
||||
|
||||
Examples:
|
||||
|
||||
```go
|
||||
type MyStruct struct{
|
||||
A int
|
||||
B string
|
||||
C time.Time
|
||||
}
|
||||
encode(MyStruct{4, "hello", time.Time("Mon Jan 2 15:04:05 -0700 MST 2006")}) ==
|
||||
[0x01, 0x04, 0x01, 0x05, 0x68, 0x65, 0x6C, 0x6C, 0x6F, 0x0F, 0xC4, 0xBB, 0xC1, 0x53, 0x03, 0x12, 0x00]
|
||||
```
|
||||
|
||||
## Merkle Trees
|
||||
|
||||
Simple Merkle trees are used in numerous places in Tendermint to compute a cryptographic digest of a data structure.
|
||||
|
||||
RIPEMD160 is always used as the hashing function.
|
||||
|
||||
The function `SimpleMerkleRoot` is a simple recursive function defined as follows:
|
||||
|
||||
```go
|
||||
func SimpleMerkleRoot(hashes [][]byte) []byte{
|
||||
switch len(hashes) {
|
||||
case 0:
|
||||
return nil
|
||||
case 1:
|
||||
return hashes[0]
|
||||
default:
|
||||
left := SimpleMerkleRoot(hashes[:(len(hashes)+1)/2])
|
||||
right := SimpleMerkleRoot(hashes[(len(hashes)+1)/2:])
|
||||
return RIPEMD160(append(left, right))
|
||||
}
|
||||
}
|
||||
```
|
||||
|
||||
Note: we abuse notion and call `SimpleMerkleRoot` with arguments of type `struct` or type `[]struct`.
|
||||
For `struct` arguments, we compute a `[][]byte` by sorting elements of the `struct` according to
|
||||
field name and then hashing them.
|
||||
For `[]struct` arguments, we compute a `[][]byte` by hashing the individual `struct` elements.
|
||||
|
||||
## JSON (TMJSON)
|
||||
|
||||
Signed messages (eg. votes, proposals) in the consensus are encoded in TMJSON, rather than TMBIN.
|
||||
TMJSON is JSON where `[]byte` are encoded as uppercase hex, rather than base64.
|
||||
|
||||
When signing, the elements of a message are sorted by key and the sorted message is embedded in an
|
||||
outer JSON that includes a `chain_id` field.
|
||||
We call this encoding the CanonicalSignBytes. For instance, CanonicalSignBytes for a vote would look
|
||||
like:
|
||||
|
||||
```json
|
||||
{"chain_id":"my-chain-id","vote":{"block_id":{"hash":DEADBEEF,"parts":{"hash":BEEFDEAD,"total":3}},"height":3,"round":2,"timestamp":1234567890, "type":2}
|
||||
```
|
||||
|
||||
Note how the fields within each level are sorted.
|
||||
|
||||
## Other
|
||||
|
||||
### MakeParts
|
||||
|
||||
Encode an object using TMBIN and slice it into parts.
|
||||
|
||||
```go
|
||||
MakeParts(object, partSize)
|
||||
```
|
||||
|
||||
### Part
|
||||
|
||||
```go
|
||||
type Part struct {
|
||||
Index int
|
||||
Bytes byte[]
|
||||
Proof byte[]
|
||||
}
|
||||
```
|
|
@ -1,192 +1 @@
|
|||
# Application Blockchain Interface (ABCI)
|
||||
|
||||
ABCI is the interface between Tendermint (a state-machine replication engine)
|
||||
and an application (the actual state machine).
|
||||
|
||||
The ABCI message types are defined in a [protobuf
|
||||
file](https://github.com/tendermint/abci/blob/master/types/types.proto).
|
||||
|
||||
For full details on the ABCI message types and protocol, see the [ABCI
|
||||
specificaiton](https://github.com/tendermint/abci/blob/master/specification.rst).
|
||||
Be sure to read the specification if you're trying to build an ABCI app!
|
||||
|
||||
For additional details on server implementation, see the [ABCI
|
||||
readme](https://github.com/tendermint/abci#implementation).
|
||||
|
||||
Here we provide some more details around the use of ABCI by Tendermint and
|
||||
clarify common "gotchas".
|
||||
|
||||
## ABCI connections
|
||||
|
||||
Tendermint opens 3 ABCI connections to the app: one for Consensus, one for
|
||||
Mempool, one for Queries.
|
||||
|
||||
## Async vs Sync
|
||||
|
||||
The main ABCI server (ie. non-GRPC) provides ordered asynchronous messages.
|
||||
This is useful for DeliverTx and CheckTx, since it allows Tendermint to forward
|
||||
transactions to the app before it's finished processing previous ones.
|
||||
|
||||
Thus, DeliverTx and CheckTx messages are sent asycnhronously, while all other
|
||||
messages are sent synchronously.
|
||||
|
||||
## CheckTx and Commit
|
||||
|
||||
It is typical to hold three distinct states in an ABCI app: CheckTxState, DeliverTxState,
|
||||
QueryState. The QueryState contains the latest committed state for a block.
|
||||
The CheckTxState and DeliverTxState may be updated concurrently with one another.
|
||||
Before Commit is called, Tendermint locks and flushes the mempool so that no new changes will happen
|
||||
to CheckTxState. When Commit completes, it unlocks the mempool.
|
||||
|
||||
Thus, during Commit, it is safe to reset the QueryState and the CheckTxState to the latest DeliverTxState
|
||||
(ie. the new state from executing all the txs in the block).
|
||||
|
||||
Note, however, that it is not possible to send transactions to Tendermint during Commit - if your app
|
||||
tries to send a `/broadcast_tx` to Tendermint during Commit, it will deadlock.
|
||||
|
||||
|
||||
## EndBlock Validator Updates
|
||||
|
||||
Updates to the Tendermint validator set can be made by returning `Validator`
|
||||
objects in the `ResponseBeginBlock`:
|
||||
|
||||
```
|
||||
message Validator {
|
||||
bytes address = 1;
|
||||
PubKey pub_key = 2;
|
||||
int64 power = 3;
|
||||
}
|
||||
|
||||
message PubKey {
|
||||
string type = 1;
|
||||
bytes data = 2;
|
||||
}
|
||||
|
||||
```
|
||||
|
||||
The `pub_key` currently supports two types:
|
||||
- `type = "ed25519" and `data = <raw 32-byte public key>`
|
||||
- `type = "secp256k1" and `data = <33-byte OpenSSL compressed public key>`
|
||||
|
||||
If the address is provided, it must match the address of the pubkey, as
|
||||
specified [here](/docs/spec/blockchain/encoding.md#Addresses)
|
||||
|
||||
(Note: In the v0.19 series, the `pub_key` is the [Amino encoded public
|
||||
key](/docs/spec/blockchain/encoding.md#public-key-cryptography).
|
||||
For Ed25519 pubkeys, the Amino prefix is always "1624DE6220". For example, the 32-byte Ed25519 pubkey
|
||||
`76852933A4686A721442E931A8415F62F5F1AEDF4910F1F252FB393F74C40C85` would be
|
||||
Amino encoded as
|
||||
`1624DE622076852933A4686A721442E931A8415F62F5F1AEDF4910F1F252FB393F74C40C85`)
|
||||
|
||||
(Note: In old versions of Tendermint (pre-v0.19.0), the pubkey is just prefixed with a
|
||||
single type byte, so for ED25519 we'd have `pub_key = 0x1 | pub`)
|
||||
|
||||
The `power` is the new voting power for the validator, with the
|
||||
following rules:
|
||||
|
||||
- power must be non-negative
|
||||
- if power is 0, the validator must already exist, and will be removed from the
|
||||
validator set
|
||||
- if power is non-0:
|
||||
- if the validator does not already exist, it will be added to the validator
|
||||
set with the given power
|
||||
- if the validator does already exist, its power will be adjusted to the given power
|
||||
|
||||
## InitChain Validator Updates
|
||||
|
||||
ResponseInitChain has the option to return a list of validators.
|
||||
If the list is not empty, Tendermint will adopt it for the validator set.
|
||||
This way the application can determine the initial validator set for the
|
||||
blockchain.
|
||||
|
||||
Note that if addressses are included in the returned validators, they must match
|
||||
the address of the public key.
|
||||
|
||||
ResponseInitChain also includes ConsensusParams, but these are presently
|
||||
ignored.
|
||||
|
||||
## Query
|
||||
|
||||
Query is a generic message type with lots of flexibility to enable diverse sets
|
||||
of queries from applications. Tendermint has no requirements from the Query
|
||||
message for normal operation - that is, the ABCI app developer need not implement Query functionality if they do not wish too.
|
||||
That said, Tendermint makes a number of queries to support some optional
|
||||
features. These are:
|
||||
|
||||
### Peer Filtering
|
||||
|
||||
When Tendermint connects to a peer, it sends two queries to the ABCI application
|
||||
using the following paths, with no additional data:
|
||||
|
||||
- `/p2p/filter/addr/<IP:PORT>`, where `<IP:PORT>` denote the IP address and
|
||||
the port of the connection
|
||||
- `p2p/filter/id/<ID>`, where `<ID>` is the peer node ID (ie. the
|
||||
pubkey.Address() for the peer's PubKey)
|
||||
|
||||
If either of these queries return a non-zero ABCI code, Tendermint will refuse
|
||||
to connect to the peer.
|
||||
|
||||
## Info and the Handshake/Replay
|
||||
|
||||
On startup, Tendermint calls Info on the Query connection to get the latest
|
||||
committed state of the app. The app MUST return information consistent with the
|
||||
last block it succesfully completed Commit for.
|
||||
|
||||
If the app succesfully committed block H but not H+1, then `last_block_height =
|
||||
H` and `last_block_app_hash = <hash returned by Commit for block H>`. If the app
|
||||
failed during the Commit of block H, then `last_block_height = H-1` and
|
||||
`last_block_app_hash = <hash returned by Commit for block H-1, which is the hash
|
||||
in the header of block H>`.
|
||||
|
||||
We now distinguish three heights, and describe how Tendermint syncs itself with
|
||||
the app.
|
||||
|
||||
```
|
||||
storeBlockHeight = height of the last block Tendermint saw a commit for
|
||||
stateBlockHeight = height of the last block for which Tendermint completed all
|
||||
block processing and saved all ABCI results to disk
|
||||
appBlockHeight = height of the last block for which ABCI app succesfully
|
||||
completely Commit
|
||||
```
|
||||
|
||||
Note we always have `storeBlockHeight >= stateBlockHeight` and `storeBlockHeight >= appBlockHeight`
|
||||
Note also we never call Commit on an ABCI app twice for the same height.
|
||||
|
||||
The procedure is as follows.
|
||||
|
||||
First, some simeple start conditions:
|
||||
|
||||
If `appBlockHeight == 0`, then call InitChain.
|
||||
|
||||
If `storeBlockHeight == 0`, we're done.
|
||||
|
||||
Now, some sanity checks:
|
||||
|
||||
If `storeBlockHeight < appBlockHeight`, error
|
||||
If `storeBlockHeight < stateBlockHeight`, panic
|
||||
If `storeBlockHeight > stateBlockHeight+1`, panic
|
||||
|
||||
Now, the meat:
|
||||
|
||||
If `storeBlockHeight == stateBlockHeight && appBlockHeight < storeBlockHeight`,
|
||||
replay all blocks in full from `appBlockHeight` to `storeBlockHeight`.
|
||||
This happens if we completed processing the block, but the app forgot its height.
|
||||
|
||||
If `storeBlockHeight == stateBlockHeight && appBlockHeight == storeBlockHeight`, we're done
|
||||
This happens if we crashed at an opportune spot.
|
||||
|
||||
If `storeBlockHeight == stateBlockHeight+1`
|
||||
This happens if we started processing the block but didn't finish.
|
||||
|
||||
If `appBlockHeight < stateBlockHeight`
|
||||
replay all blocks in full from `appBlockHeight` to `storeBlockHeight-1`,
|
||||
and replay the block at `storeBlockHeight` using the WAL.
|
||||
This happens if the app forgot the last block it committed.
|
||||
|
||||
If `appBlockHeight == stateBlockHeight`,
|
||||
replay the last block (storeBlockHeight) in full.
|
||||
This happens if we crashed before the app finished Commit
|
||||
|
||||
If appBlockHeight == storeBlockHeight {
|
||||
update the state using the saved ABCI responses but dont run the block against the real app.
|
||||
This happens if we crashed after the app finished Commit but before Tendermint saved the state.
|
||||
[Moved](/docs/spec/software/abci.md)
|
||||
|
|
|
@ -0,0 +1,9 @@
|
|||
We are working to finalize an updated Tendermint specification with formal
|
||||
proofs of safety and liveness.
|
||||
|
||||
In the meantime, see the [description in the
|
||||
docs](http://tendermint.readthedocs.io/en/master/specification/byzantine-consensus-algorithm.html).
|
||||
|
||||
There are also relevant but somewhat outdated descriptions in Jae Kwon's [original
|
||||
whitepaper](https://tendermint.com/static/docs/tendermint.pdf) and Ethan Buchman's [master's
|
||||
thesis](https://atrium.lib.uoguelph.ca/xmlui/handle/10214/9769).
|
|
@ -1,33 +1 @@
|
|||
# WAL
|
||||
|
||||
Consensus module writes every message to the WAL (write-ahead log).
|
||||
|
||||
It also issues fsync syscall through
|
||||
[File#Sync](https://golang.org/pkg/os/#File.Sync) for messages signed by this
|
||||
node (to prevent double signing).
|
||||
|
||||
Under the hood, it uses
|
||||
[autofile.Group](https://godoc.org/github.com/tendermint/tmlibs/autofile#Group),
|
||||
which rotates files when those get too big (> 10MB).
|
||||
|
||||
The total maximum size is 1GB. We only need the latest block and the block before it,
|
||||
but if the former is dragging on across many rounds, we want all those rounds.
|
||||
|
||||
## Replay
|
||||
|
||||
Consensus module will replay all the messages of the last height written to WAL
|
||||
before a crash (if such occurs).
|
||||
|
||||
The private validator may try to sign messages during replay because it runs
|
||||
somewhat autonomously and does not know about replay process.
|
||||
|
||||
For example, if we got all the way to precommit in the WAL and then crash,
|
||||
after we replay the proposal message, the private validator will try to sign a
|
||||
prevote. But it will fail. That's ok because we’ll see the prevote later in the
|
||||
WAL. Then it will go to precommit, and that time it will work because the
|
||||
private validator contains the `LastSignBytes` and then we’ll replay the
|
||||
precommit from the WAL.
|
||||
|
||||
Make sure to read about [WAL
|
||||
corruption](https://tendermint.readthedocs.io/projects/tools/en/master/specification/corruption.html#wal-corruption)
|
||||
and recovery strategies.
|
||||
[Moved](/docs/spec/software/wal.md)
|
||||
|
|
|
@ -0,0 +1,192 @@
|
|||
# Application Blockchain Interface (ABCI)
|
||||
|
||||
ABCI is the interface between Tendermint (a state-machine replication engine)
|
||||
and an application (the actual state machine).
|
||||
|
||||
The ABCI message types are defined in a [protobuf
|
||||
file](https://github.com/tendermint/abci/blob/master/types/types.proto).
|
||||
|
||||
For full details on the ABCI message types and protocol, see the [ABCI
|
||||
specificaiton](https://github.com/tendermint/abci/blob/master/specification.rst).
|
||||
Be sure to read the specification if you're trying to build an ABCI app!
|
||||
|
||||
For additional details on server implementation, see the [ABCI
|
||||
readme](https://github.com/tendermint/abci#implementation).
|
||||
|
||||
Here we provide some more details around the use of ABCI by Tendermint and
|
||||
clarify common "gotchas".
|
||||
|
||||
## ABCI connections
|
||||
|
||||
Tendermint opens 3 ABCI connections to the app: one for Consensus, one for
|
||||
Mempool, one for Queries.
|
||||
|
||||
## Async vs Sync
|
||||
|
||||
The main ABCI server (ie. non-GRPC) provides ordered asynchronous messages.
|
||||
This is useful for DeliverTx and CheckTx, since it allows Tendermint to forward
|
||||
transactions to the app before it's finished processing previous ones.
|
||||
|
||||
Thus, DeliverTx and CheckTx messages are sent asycnhronously, while all other
|
||||
messages are sent synchronously.
|
||||
|
||||
## CheckTx and Commit
|
||||
|
||||
It is typical to hold three distinct states in an ABCI app: CheckTxState, DeliverTxState,
|
||||
QueryState. The QueryState contains the latest committed state for a block.
|
||||
The CheckTxState and DeliverTxState may be updated concurrently with one another.
|
||||
Before Commit is called, Tendermint locks and flushes the mempool so that no new changes will happen
|
||||
to CheckTxState. When Commit completes, it unlocks the mempool.
|
||||
|
||||
Thus, during Commit, it is safe to reset the QueryState and the CheckTxState to the latest DeliverTxState
|
||||
(ie. the new state from executing all the txs in the block).
|
||||
|
||||
Note, however, that it is not possible to send transactions to Tendermint during Commit - if your app
|
||||
tries to send a `/broadcast_tx` to Tendermint during Commit, it will deadlock.
|
||||
|
||||
|
||||
## EndBlock Validator Updates
|
||||
|
||||
Updates to the Tendermint validator set can be made by returning `Validator`
|
||||
objects in the `ResponseBeginBlock`:
|
||||
|
||||
```
|
||||
message Validator {
|
||||
bytes address = 1;
|
||||
PubKey pub_key = 2;
|
||||
int64 power = 3;
|
||||
}
|
||||
|
||||
message PubKey {
|
||||
string type = 1;
|
||||
bytes data = 2;
|
||||
}
|
||||
|
||||
```
|
||||
|
||||
The `pub_key` currently supports two types:
|
||||
- `type = "ed25519" and `data = <raw 32-byte public key>`
|
||||
- `type = "secp256k1" and `data = <33-byte OpenSSL compressed public key>`
|
||||
|
||||
If the address is provided, it must match the address of the pubkey, as
|
||||
specified [here](/docs/spec/blockchain/encoding.md#Addresses)
|
||||
|
||||
(Note: In the v0.19 series, the `pub_key` is the [Amino encoded public
|
||||
key](/docs/spec/blockchain/encoding.md#public-key-cryptography).
|
||||
For Ed25519 pubkeys, the Amino prefix is always "1624DE6220". For example, the 32-byte Ed25519 pubkey
|
||||
`76852933A4686A721442E931A8415F62F5F1AEDF4910F1F252FB393F74C40C85` would be
|
||||
Amino encoded as
|
||||
`1624DE622076852933A4686A721442E931A8415F62F5F1AEDF4910F1F252FB393F74C40C85`)
|
||||
|
||||
(Note: In old versions of Tendermint (pre-v0.19.0), the pubkey is just prefixed with a
|
||||
single type byte, so for ED25519 we'd have `pub_key = 0x1 | pub`)
|
||||
|
||||
The `power` is the new voting power for the validator, with the
|
||||
following rules:
|
||||
|
||||
- power must be non-negative
|
||||
- if power is 0, the validator must already exist, and will be removed from the
|
||||
validator set
|
||||
- if power is non-0:
|
||||
- if the validator does not already exist, it will be added to the validator
|
||||
set with the given power
|
||||
- if the validator does already exist, its power will be adjusted to the given power
|
||||
|
||||
## InitChain Validator Updates
|
||||
|
||||
ResponseInitChain has the option to return a list of validators.
|
||||
If the list is not empty, Tendermint will adopt it for the validator set.
|
||||
This way the application can determine the initial validator set for the
|
||||
blockchain.
|
||||
|
||||
Note that if addressses are included in the returned validators, they must match
|
||||
the address of the public key.
|
||||
|
||||
ResponseInitChain also includes ConsensusParams, but these are presently
|
||||
ignored.
|
||||
|
||||
## Query
|
||||
|
||||
Query is a generic message type with lots of flexibility to enable diverse sets
|
||||
of queries from applications. Tendermint has no requirements from the Query
|
||||
message for normal operation - that is, the ABCI app developer need not implement Query functionality if they do not wish too.
|
||||
That said, Tendermint makes a number of queries to support some optional
|
||||
features. These are:
|
||||
|
||||
### Peer Filtering
|
||||
|
||||
When Tendermint connects to a peer, it sends two queries to the ABCI application
|
||||
using the following paths, with no additional data:
|
||||
|
||||
- `/p2p/filter/addr/<IP:PORT>`, where `<IP:PORT>` denote the IP address and
|
||||
the port of the connection
|
||||
- `p2p/filter/id/<ID>`, where `<ID>` is the peer node ID (ie. the
|
||||
pubkey.Address() for the peer's PubKey)
|
||||
|
||||
If either of these queries return a non-zero ABCI code, Tendermint will refuse
|
||||
to connect to the peer.
|
||||
|
||||
## Info and the Handshake/Replay
|
||||
|
||||
On startup, Tendermint calls Info on the Query connection to get the latest
|
||||
committed state of the app. The app MUST return information consistent with the
|
||||
last block it succesfully completed Commit for.
|
||||
|
||||
If the app succesfully committed block H but not H+1, then `last_block_height =
|
||||
H` and `last_block_app_hash = <hash returned by Commit for block H>`. If the app
|
||||
failed during the Commit of block H, then `last_block_height = H-1` and
|
||||
`last_block_app_hash = <hash returned by Commit for block H-1, which is the hash
|
||||
in the header of block H>`.
|
||||
|
||||
We now distinguish three heights, and describe how Tendermint syncs itself with
|
||||
the app.
|
||||
|
||||
```
|
||||
storeBlockHeight = height of the last block Tendermint saw a commit for
|
||||
stateBlockHeight = height of the last block for which Tendermint completed all
|
||||
block processing and saved all ABCI results to disk
|
||||
appBlockHeight = height of the last block for which ABCI app succesfully
|
||||
completely Commit
|
||||
```
|
||||
|
||||
Note we always have `storeBlockHeight >= stateBlockHeight` and `storeBlockHeight >= appBlockHeight`
|
||||
Note also we never call Commit on an ABCI app twice for the same height.
|
||||
|
||||
The procedure is as follows.
|
||||
|
||||
First, some simeple start conditions:
|
||||
|
||||
If `appBlockHeight == 0`, then call InitChain.
|
||||
|
||||
If `storeBlockHeight == 0`, we're done.
|
||||
|
||||
Now, some sanity checks:
|
||||
|
||||
If `storeBlockHeight < appBlockHeight`, error
|
||||
If `storeBlockHeight < stateBlockHeight`, panic
|
||||
If `storeBlockHeight > stateBlockHeight+1`, panic
|
||||
|
||||
Now, the meat:
|
||||
|
||||
If `storeBlockHeight == stateBlockHeight && appBlockHeight < storeBlockHeight`,
|
||||
replay all blocks in full from `appBlockHeight` to `storeBlockHeight`.
|
||||
This happens if we completed processing the block, but the app forgot its height.
|
||||
|
||||
If `storeBlockHeight == stateBlockHeight && appBlockHeight == storeBlockHeight`, we're done
|
||||
This happens if we crashed at an opportune spot.
|
||||
|
||||
If `storeBlockHeight == stateBlockHeight+1`
|
||||
This happens if we started processing the block but didn't finish.
|
||||
|
||||
If `appBlockHeight < stateBlockHeight`
|
||||
replay all blocks in full from `appBlockHeight` to `storeBlockHeight-1`,
|
||||
and replay the block at `storeBlockHeight` using the WAL.
|
||||
This happens if the app forgot the last block it committed.
|
||||
|
||||
If `appBlockHeight == stateBlockHeight`,
|
||||
replay the last block (storeBlockHeight) in full.
|
||||
This happens if we crashed before the app finished Commit
|
||||
|
||||
If appBlockHeight == storeBlockHeight {
|
||||
update the state using the saved ABCI responses but dont run the block against the real app.
|
||||
This happens if we crashed after the app finished Commit but before Tendermint saved the state.
|
|
@ -0,0 +1,33 @@
|
|||
# WAL
|
||||
|
||||
Consensus module writes every message to the WAL (write-ahead log).
|
||||
|
||||
It also issues fsync syscall through
|
||||
[File#Sync](https://golang.org/pkg/os/#File.Sync) for messages signed by this
|
||||
node (to prevent double signing).
|
||||
|
||||
Under the hood, it uses
|
||||
[autofile.Group](https://godoc.org/github.com/tendermint/tmlibs/autofile#Group),
|
||||
which rotates files when those get too big (> 10MB).
|
||||
|
||||
The total maximum size is 1GB. We only need the latest block and the block before it,
|
||||
but if the former is dragging on across many rounds, we want all those rounds.
|
||||
|
||||
## Replay
|
||||
|
||||
Consensus module will replay all the messages of the last height written to WAL
|
||||
before a crash (if such occurs).
|
||||
|
||||
The private validator may try to sign messages during replay because it runs
|
||||
somewhat autonomously and does not know about replay process.
|
||||
|
||||
For example, if we got all the way to precommit in the WAL and then crash,
|
||||
after we replay the proposal message, the private validator will try to sign a
|
||||
prevote. But it will fail. That's ok because we’ll see the prevote later in the
|
||||
WAL. Then it will go to precommit, and that time it will work because the
|
||||
private validator contains the `LastSignBytes` and then we’ll replay the
|
||||
precommit from the WAL.
|
||||
|
||||
Make sure to read about [WAL
|
||||
corruption](https://tendermint.readthedocs.io/projects/tools/en/master/specification/corruption.html#wal-corruption)
|
||||
and recovery strategies.
|
Loading…
Reference in New Issue