mirror of
https://source.quilibrium.com/quilibrium/ceremonyclient.git
synced 2024-11-10 18:25:17 +00:00
301 lines
9.3 KiB
Go
301 lines
9.3 KiB
Go
// Copyright 2023 The LevelDB-Go and Pebble Authors. All rights reserved. Use
|
|
// of this source code is governed by a BSD-style license that can be found in
|
|
// the LICENSE file.
|
|
|
|
package errorfs
|
|
|
|
import (
|
|
"encoding/binary"
|
|
"fmt"
|
|
"go/token"
|
|
"hash/maphash"
|
|
"math/rand"
|
|
"path/filepath"
|
|
"strconv"
|
|
"sync"
|
|
|
|
"github.com/cockroachdb/errors"
|
|
"github.com/cockroachdb/pebble/internal/dsl"
|
|
)
|
|
|
|
// Predicate encodes conditional logic that determines whether to inject an
|
|
// error.
|
|
type Predicate = dsl.Predicate[Op]
|
|
|
|
// PathMatch returns a predicate that returns true if an operation's file path
|
|
// matches the provided pattern according to filepath.Match.
|
|
func PathMatch(pattern string) Predicate {
|
|
return &pathMatch{pattern: pattern}
|
|
}
|
|
|
|
type pathMatch struct {
|
|
pattern string
|
|
}
|
|
|
|
func (pm *pathMatch) String() string {
|
|
return fmt.Sprintf("(PathMatch %q)", pm.pattern)
|
|
}
|
|
|
|
func (pm *pathMatch) Evaluate(op Op) bool {
|
|
matched, err := filepath.Match(pm.pattern, op.Path)
|
|
if err != nil {
|
|
// Only possible error is ErrBadPattern, indicating an issue with
|
|
// the test itself.
|
|
panic(err)
|
|
}
|
|
return matched
|
|
}
|
|
|
|
var (
|
|
// Reads is a predicate that returns true iff an operation is a read
|
|
// operation.
|
|
Reads Predicate = opKindPred{kind: OpIsRead}
|
|
// Writes is a predicate that returns true iff an operation is a write
|
|
// operation.
|
|
Writes Predicate = opKindPred{kind: OpIsWrite}
|
|
)
|
|
|
|
type opFileReadAt struct {
|
|
// offset configures the predicate to evaluate to true only if the
|
|
// operation's offset exactly matches offset.
|
|
offset int64
|
|
}
|
|
|
|
func (o *opFileReadAt) String() string {
|
|
return fmt.Sprintf("(FileReadAt %d)", o.offset)
|
|
}
|
|
|
|
func (o *opFileReadAt) Evaluate(op Op) bool {
|
|
return op.Kind == OpFileReadAt && o.offset == op.Offset
|
|
}
|
|
|
|
type opKindPred struct {
|
|
kind OpReadWrite
|
|
}
|
|
|
|
func (p opKindPred) String() string { return p.kind.String() }
|
|
func (p opKindPred) Evaluate(op Op) bool { return p.kind == op.Kind.ReadOrWrite() }
|
|
|
|
// Randomly constructs a new predicate that pseudorandomly evaluates to true
|
|
// with probability p using randomness determinstically derived from seed.
|
|
//
|
|
// The predicate is deterministic with respect to file paths: its behavior for a
|
|
// particular file is deterministic regardless of intervening evaluations for
|
|
// operations on other files. This can be used to ensure determinism despite
|
|
// nondeterministic concurrency if the concurrency is constrained to separate
|
|
// files.
|
|
func Randomly(p float64, seed int64) Predicate {
|
|
rs := &randomSeed{p: p, rootSeed: seed}
|
|
rs.mu.perFilePrng = make(map[string]*rand.Rand)
|
|
return rs
|
|
}
|
|
|
|
type randomSeed struct {
|
|
// p defines the probability of an error being injected.
|
|
p float64
|
|
rootSeed int64
|
|
mu struct {
|
|
sync.Mutex
|
|
h maphash.Hash
|
|
perFilePrng map[string]*rand.Rand
|
|
}
|
|
}
|
|
|
|
func (rs *randomSeed) String() string {
|
|
if rs.rootSeed == 0 {
|
|
return fmt.Sprintf("(Randomly %.2f)", rs.p)
|
|
}
|
|
return fmt.Sprintf("(Randomly %.2f %d)", rs.p, rs.rootSeed)
|
|
}
|
|
|
|
func (rs *randomSeed) Evaluate(op Op) bool {
|
|
rs.mu.Lock()
|
|
defer rs.mu.Unlock()
|
|
prng, ok := rs.mu.perFilePrng[op.Path]
|
|
if !ok {
|
|
// This is the first time an operation has been performed on the file at
|
|
// this path. Initialize the per-file prng by computing a deterministic
|
|
// hash of the path.
|
|
rs.mu.h.Reset()
|
|
var b [8]byte
|
|
binary.LittleEndian.PutUint64(b[:], uint64(rs.rootSeed))
|
|
if _, err := rs.mu.h.Write(b[:]); err != nil {
|
|
panic(err)
|
|
}
|
|
if _, err := rs.mu.h.WriteString(op.Path); err != nil {
|
|
panic(err)
|
|
}
|
|
seed := rs.mu.h.Sum64()
|
|
prng = rand.New(rand.NewSource(int64(seed)))
|
|
rs.mu.perFilePrng[op.Path] = prng
|
|
}
|
|
return prng.Float64() < rs.p
|
|
}
|
|
|
|
// ParseDSL parses the provided string using the default DSL parser.
|
|
func ParseDSL(s string) (Injector, error) {
|
|
return defaultParser.Parse(s)
|
|
}
|
|
|
|
var defaultParser = NewParser()
|
|
|
|
// NewParser constructs a new parser for an encoding of a lisp-like DSL
|
|
// describing error injectors.
|
|
//
|
|
// Errors:
|
|
// - ErrInjected is the only error currently supported by the DSL.
|
|
//
|
|
// Injectors:
|
|
// - <ERROR>: An error by itself is an injector that injects an error every
|
|
// time.
|
|
// - (<ERROR> <PREDICATE>) is an injector that injects an error only when
|
|
// the operation satisfies the predicate.
|
|
//
|
|
// Predicates:
|
|
// - Reads is a constant predicate that evalutes to true iff the operation is a
|
|
// read operation (eg, Open, Read, ReadAt, Stat)
|
|
// - Writes is a constant predicate that evaluates to true iff the operation is
|
|
// a write operation (eg, Create, Rename, Write, WriteAt, etc).
|
|
// - (PathMatch <STRING>) is a predicate that evalutes to true iff the
|
|
// operation's file path matches the provided shell pattern.
|
|
// - (OnIndex <INTEGER>) is a predicate that evaluates to true only on the n-th
|
|
// invocation.
|
|
// - (And <PREDICATE> [PREDICATE]...) is a predicate that evaluates to true
|
|
// iff all the provided predicates evaluate to true. And short circuits on
|
|
// the first predicate to evaluate to false.
|
|
// - (Or <PREDICATE> [PREDICATE]...) is a predicate that evaluates to true iff
|
|
// at least one of the provided predicates evaluates to true. Or short
|
|
// circuits on the first predicate to evaluate to true.
|
|
// - (Not <PREDICATE>) is a predicate that evaluates to true iff its provided
|
|
// predicates evaluates to false.
|
|
// - (Randomly <FLOAT> [INTEGER]) is a predicate that pseudorandomly evaluates
|
|
// to true. The probability of evaluating to true is determined by the
|
|
// required float argument (must be ≤1). The optional second parameter is a
|
|
// pseudorandom seed, for adjusting the deterministic randomness.
|
|
// - Operation-specific:
|
|
// (OpFileReadAt <INTEGER>) is a predicate that evaluates to true iff
|
|
// an operation is a file ReadAt call with an offset that's exactly equal.
|
|
//
|
|
// Example: (ErrInjected (And (PathMatch "*.sst") (OnIndex 5))) is a rule set
|
|
// that will inject an error on the 5-th I/O operation involving an sstable.
|
|
func NewParser() *Parser {
|
|
p := &Parser{
|
|
predicates: dsl.NewPredicateParser[Op](),
|
|
injectors: dsl.NewParser[Injector](),
|
|
}
|
|
p.predicates.DefineConstant("Reads", func() dsl.Predicate[Op] { return Reads })
|
|
p.predicates.DefineConstant("Writes", func() dsl.Predicate[Op] { return Writes })
|
|
p.predicates.DefineFunc("PathMatch",
|
|
func(p *dsl.Parser[dsl.Predicate[Op]], s *dsl.Scanner) dsl.Predicate[Op] {
|
|
pattern := s.ConsumeString()
|
|
s.Consume(token.RPAREN)
|
|
return PathMatch(pattern)
|
|
})
|
|
p.predicates.DefineFunc("OpFileReadAt",
|
|
func(p *dsl.Parser[dsl.Predicate[Op]], s *dsl.Scanner) dsl.Predicate[Op] {
|
|
return parseFileReadAtOp(s)
|
|
})
|
|
p.predicates.DefineFunc("Randomly",
|
|
func(p *dsl.Parser[dsl.Predicate[Op]], s *dsl.Scanner) dsl.Predicate[Op] {
|
|
return parseRandomly(s)
|
|
})
|
|
p.AddError(ErrInjected)
|
|
return p
|
|
}
|
|
|
|
// A Parser parses the error-injecting DSL. It may be extended to include
|
|
// additional errors through AddError.
|
|
type Parser struct {
|
|
predicates *dsl.Parser[dsl.Predicate[Op]]
|
|
injectors *dsl.Parser[Injector]
|
|
}
|
|
|
|
// Parse parses the error injection DSL, returning the parsed injector.
|
|
func (p *Parser) Parse(s string) (Injector, error) {
|
|
return p.injectors.Parse(s)
|
|
}
|
|
|
|
// AddError defines a new error that may be used within the DSL parsed by
|
|
// Parse and will inject the provided error.
|
|
func (p *Parser) AddError(le LabelledError) {
|
|
// Define the error both as a constant that unconditionally injects the
|
|
// error, and as a function that injects the error only if the provided
|
|
// predicate evaluates to true.
|
|
p.injectors.DefineConstant(le.Label, func() Injector { return le })
|
|
p.injectors.DefineFunc(le.Label,
|
|
func(_ *dsl.Parser[Injector], s *dsl.Scanner) Injector {
|
|
pred := p.predicates.ParseFromPos(s, s.Scan())
|
|
s.Consume(token.RPAREN)
|
|
return le.If(pred)
|
|
})
|
|
}
|
|
|
|
// LabelledError is an error that also implements Injector, unconditionally
|
|
// injecting itself. It implements String() by returning its label. It
|
|
// implements Error() by returning its underlying error.
|
|
type LabelledError struct {
|
|
error
|
|
Label string
|
|
predicate Predicate
|
|
}
|
|
|
|
// String implements fmt.Stringer.
|
|
func (le LabelledError) String() string {
|
|
if le.predicate == nil {
|
|
return le.Label
|
|
}
|
|
return fmt.Sprintf("(%s %s)", le.Label, le.predicate.String())
|
|
}
|
|
|
|
// MaybeError implements Injector.
|
|
func (le LabelledError) MaybeError(op Op) error {
|
|
if le.predicate == nil || le.predicate.Evaluate(op) {
|
|
return le
|
|
}
|
|
return nil
|
|
}
|
|
|
|
// If returns an Injector that returns the receiver error if the provided
|
|
// predicate evalutes to true.
|
|
func (le LabelledError) If(p Predicate) Injector {
|
|
le.predicate = p
|
|
return le
|
|
}
|
|
|
|
func parseFileReadAtOp(s *dsl.Scanner) *opFileReadAt {
|
|
lit := s.Consume(token.INT).Lit
|
|
off, err := strconv.ParseInt(lit, 10, 64)
|
|
if err != nil {
|
|
panic(err)
|
|
}
|
|
s.Consume(token.RPAREN)
|
|
return &opFileReadAt{offset: off}
|
|
}
|
|
|
|
func parseRandomly(s *dsl.Scanner) Predicate {
|
|
lit := s.Consume(token.FLOAT).Lit
|
|
p, err := strconv.ParseFloat(lit, 64)
|
|
if err != nil {
|
|
panic(err)
|
|
} else if p > 1.0 {
|
|
// NB: It's not possible for p to be less than zero because we don't
|
|
// try to parse the '-' token.
|
|
panic(errors.Newf("errorfs: Randomly proability p must be within p ≤ 1.0"))
|
|
}
|
|
|
|
var seed int64
|
|
tok := s.Scan()
|
|
switch tok.Kind {
|
|
case token.RPAREN:
|
|
case token.INT:
|
|
seed, err = strconv.ParseInt(tok.Lit, 10, 64)
|
|
if err != nil {
|
|
panic(err)
|
|
}
|
|
s.Consume(token.RPAREN)
|
|
default:
|
|
panic(errors.Errorf("errorfs: unexpected token %s; expected RPAREN | FLOAT", tok.String()))
|
|
}
|
|
return Randomly(p, seed)
|
|
}
|