Files
visor/pkg/sentry/usage/io.go
T
Kevin KrakauerandgVisor bot b8dd528b97 prohibit direct use of sync/atomic (u)int64 functions
All atomic 64 bit ints are changed to atomicbitops.(Ui|I)nt64. A nogo checker
enforces that sync/atomic 64 bit functions are not called.

For reviewers: the interesting changes are in the atomicbitops and checkaligned
packages.

Why do this?
- It is very easy to accidentally use atomic values without sync/atomic funcs.
- We have checkatomics, but this is optional and is forgotten in several places.
  - Using a type+checker to enforce this seems less error prone and simpler.
- We get NoCopy protection.
- Use of 64 bit atomics can break 32 bit builds. We have types to handle this
  without any runtime cost, so we might as well use them.

PiperOrigin-RevId: 440473398
2022-04-08 16:06:26 -07:00

100 lines
3.0 KiB
Go

// Copyright 2018 The gVisor Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package usage
import "gvisor.dev/gvisor/pkg/atomicbitops"
// IO contains I/O-related statistics.
//
// +stateify savable
type IO struct {
// CharsRead is the number of bytes read by read syscalls.
CharsRead atomicbitops.Uint64
// CharsWritten is the number of bytes written by write syscalls.
CharsWritten atomicbitops.Uint64
// ReadSyscalls is the number of read syscalls.
ReadSyscalls atomicbitops.Uint64
// WriteSyscalls is the number of write syscalls.
WriteSyscalls atomicbitops.Uint64
// The following counter is only meaningful when Sentry has internal
// pagecache.
// BytesRead is the number of bytes actually read into pagecache.
BytesRead atomicbitops.Uint64
// BytesWritten is the number of bytes actually written from pagecache.
BytesWritten atomicbitops.Uint64
// BytesWriteCancelled is the number of bytes not written out due to
// truncation.
BytesWriteCancelled atomicbitops.Uint64
}
// Clone turns other into a clone of i.
func (i *IO) Clone(other *IO) {
other.CharsRead.Store(i.CharsRead.Load())
other.CharsWritten.Store(i.CharsWritten.Load())
other.ReadSyscalls.Store(i.ReadSyscalls.Load())
other.WriteSyscalls.Store(i.WriteSyscalls.Load())
other.BytesRead.Store(i.BytesRead.Load())
other.BytesWritten.Store(i.BytesWritten.Load())
other.BytesWriteCancelled.Store(i.BytesWriteCancelled.Load())
}
// AccountReadSyscall does the accounting for a read syscall.
func (i *IO) AccountReadSyscall(bytes int64) {
i.ReadSyscalls.Add(1)
if bytes > 0 {
i.CharsRead.Add(uint64(bytes))
}
}
// AccountWriteSyscall does the accounting for a write syscall.
func (i *IO) AccountWriteSyscall(bytes int64) {
i.WriteSyscalls.Add(1)
if bytes > 0 {
i.CharsWritten.Add(uint64(bytes))
}
}
// AccountReadIO does the accounting for a read IO into the file system.
func (i *IO) AccountReadIO(bytes int64) {
if bytes > 0 {
i.BytesRead.Add(uint64(bytes))
}
}
// AccountWriteIO does the accounting for a write IO into the file system.
func (i *IO) AccountWriteIO(bytes int64) {
if bytes > 0 {
i.BytesWritten.Add(uint64(bytes))
}
}
// Accumulate adds up io usages.
func (i *IO) Accumulate(io *IO) {
i.CharsRead.Add(io.CharsRead.Load())
i.CharsWritten.Add(io.CharsWritten.Load())
i.ReadSyscalls.Add(io.ReadSyscalls.Load())
i.WriteSyscalls.Add(io.WriteSyscalls.Load())
i.BytesRead.Add(io.BytesRead.Load())
i.BytesWritten.Add(io.BytesWritten.Load())
i.BytesWriteCancelled.Add(io.BytesWriteCancelled.Load())
}