ceremonyclient/pebble/internal/cache/value_invariants.go
Cassandra Heart 2e2a1e4789
v1.2.0 (#31)
2024-01-03 01:31:42 -06:00

56 lines
1.5 KiB
Go

// Copyright 2020 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.
//go:build (invariants && !race) || (tracing && !race)
// +build invariants,!race tracing,!race
package cache
import (
"fmt"
"os"
"github.com/cockroachdb/pebble/internal/invariants"
"github.com/cockroachdb/pebble/internal/manual"
)
// newValue creates a Value with a manually managed buffer of size n.
//
// This definition of newValue is used when either the "invariants" or
// "tracing" build tags are specified. It hooks up a finalizer to the returned
// Value that checks for memory leaks when the GC determines the Value is no
// longer reachable.
func newValue(n int) *Value {
if n == 0 {
return nil
}
b := manual.New(n)
v := &Value{buf: b}
v.ref.init(1)
// Note: this is a no-op if invariants and tracing are disabled or race is
// enabled.
invariants.SetFinalizer(v, func(obj interface{}) {
v := obj.(*Value)
if v.buf != nil {
fmt.Fprintf(os.Stderr, "%p: cache value was not freed: refs=%d\n%s",
v, v.refs(), v.ref.traces())
os.Exit(1)
}
})
return v
}
func (v *Value) free() {
// When "invariants" are enabled set the value contents to 0xff in order to
// cache use-after-free bugs.
for i := range v.buf {
v.buf[i] = 0xff
}
manual.Free(v.buf)
// Setting Value.buf to nil is needed for correctness of the leak checking
// that is performed when the "invariants" or "tracing" build tags are
// enabled.
v.buf = nil
}