1 files changed, 90 insertions, 0 deletions
diff --git a/pkg/sentry/usage/io.go b/pkg/sentry/usage/io.go
new file mode 100644
index 000000000..dfcd3a49d
--- /dev/null
+++ b/pkg/sentry/usage/io.go
@@ -0,0 +1,90 @@
+// 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 (
+	"sync/atomic"
+)
+
+// IO contains I/O-related statistics.
+//
+// +stateify savable
+type IO struct {
+	// CharsRead is the number of bytes read by read syscalls.
+	CharsRead uint64
+
+	// CharsWritten is the number of bytes written by write syscalls.
+	CharsWritten uint64
+
+	// ReadSyscalls is the number of read syscalls.
+	ReadSyscalls uint64
+
+	// WriteSyscalls is the number of write syscalls.
+	WriteSyscalls uint64
+
+	// The following counter is only meaningful when Sentry has internal
+	// pagecache.
+
+	// BytesRead is the number of bytes actually read into pagecache.
+	BytesRead uint64
+
+	// BytesWritten is the number of bytes actually written from pagecache.
+	BytesWritten uint64
+
+	// BytesWriteCancelled is the number of bytes not written out due to
+	// truncation.
+	BytesWriteCancelled uint64
+}
+
+// AccountReadSyscall does the accounting for a read syscall.
+func (i *IO) AccountReadSyscall(bytes int64) {
+	atomic.AddUint64(&i.ReadSyscalls, 1)
+	if bytes > 0 {
+		atomic.AddUint64(&i.CharsRead, uint64(bytes))
+	}
+}
+
+// AccountWriteSyscall does the accounting for a write syscall.
+func (i *IO) AccountWriteSyscall(bytes int64) {
+	atomic.AddUint64(&i.WriteSyscalls, 1)
+	if bytes > 0 {
+		atomic.AddUint64(&i.CharsWritten, uint64(bytes))
+	}
+}
+
+// AccountReadIO does the accounting for a read IO into the file system.
+func (i *IO) AccountReadIO(bytes int64) {
+	if bytes > 0 {
+		atomic.AddUint64(&i.BytesRead, uint64(bytes))
+	}
+}
+
+// AccountWriteIO does the accounting for a write IO into the file system.
+func (i *IO) AccountWriteIO(bytes int64) {
+	if bytes > 0 {
+		atomic.AddUint64(&i.BytesWritten, uint64(bytes))
+	}
+}
+
+// Accumulate adds up io usages.
+func (i *IO) Accumulate(io *IO) {
+	atomic.AddUint64(&i.CharsRead, atomic.LoadUint64(&io.CharsRead))
+	atomic.AddUint64(&i.CharsWritten, atomic.LoadUint64(&io.CharsWritten))
+	atomic.AddUint64(&i.ReadSyscalls, atomic.LoadUint64(&io.ReadSyscalls))
+	atomic.AddUint64(&i.WriteSyscalls, atomic.LoadUint64(&io.WriteSyscalls))
+	atomic.AddUint64(&i.BytesRead, atomic.LoadUint64(&io.BytesRead))
+	atomic.AddUint64(&i.BytesWritten, atomic.LoadUint64(&io.BytesWritten))
+	atomic.AddUint64(&i.BytesWriteCancelled, atomic.LoadUint64(&io.BytesWriteCancelled))
+}