fusego/fuseops/common_op.go

113 lines
2.6 KiB
Go

// Copyright 2015 Google Inc. All Rights Reserved.
//
// 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 fuseops
import (
"reflect"
"sync"
"github.com/jacobsa/bazilfuse"
"github.com/jacobsa/reqtrace"
"golang.org/x/net/context"
)
// A helper for embedding common behavior.
type commonOp struct {
ctx context.Context
opType string
r bazilfuse.Request
log func(int, string, ...interface{})
opsInFlight *sync.WaitGroup
report reqtrace.ReportFunc
}
func describeOpType(t reflect.Type) (desc string) {
// TODO(jacobsa): Make this nicer.
desc = t.String()
return
}
func (o *commonOp) init(
opType reflect.Type,
r bazilfuse.Request,
log func(int, string, ...interface{}),
opsInFlight *sync.WaitGroup) {
// Initialize basic fields.
o.opType = describeOpType(opType)
o.ctx = context.Background()
o.r = r
o.log = log
o.opsInFlight = opsInFlight
// Set up a trace span for this op.
o.ctx, o.report = reqtrace.StartSpan(o.ctx, o.opType)
}
func (o *commonOp) Header() OpHeader {
bh := o.r.Hdr()
return OpHeader{
Uid: bh.Uid,
Gid: bh.Gid,
}
}
func (o *commonOp) Context() context.Context {
return o.ctx
}
func (o *commonOp) Logf(format string, v ...interface{}) {
const calldepth = 2
o.log(calldepth, format, v...)
}
func (o *commonOp) respondErr(err error) {
if err == nil {
panic("Expect non-nil here.")
}
o.report(err)
o.Logf(
"-> (%s) error: %v",
o.opType,
err)
o.r.RespondError(err)
}
// Respond with the supplied response struct, which must be accepted by a
// method called Respond on o.r.
//
// Special case: nil means o.r.Respond accepts no parameters.
func (o *commonOp) respond(resp interface{}) {
// We were successful.
o.report(nil)
// Find the Respond method.
v := reflect.ValueOf(o.r)
respond := v.MethodByName("Respond")
// Special case: handle successful ops with no response struct.
if resp == nil {
o.Logf("-> (%s) OK", o.opType)
respond.Call([]reflect.Value{})
return
}
// Otherwise, pass along the response struct.
o.Logf("-> %v", resp)
respond.Call([]reflect.Value{reflect.ValueOf(resp)})
}