diff options
author | Frédéric Guillot <fred@miniflux.net> | 2018-08-26 16:43:53 -0700 |
---|---|---|
committer | Frédéric Guillot <fred@miniflux.net> | 2018-08-26 16:43:53 -0700 |
commit | a3f3f51c60e91f22cc57ecc23cf828421d46b6b7 (patch) | |
tree | e037378ae0ca1f09cfb0eb46e289f28f857c2aed /vendor/google.golang.org/appengine/delay/delay.go | |
parent | a9e9c347f4d385b4a297a45be96cddfc3a1c7814 (diff) |
Migrate to go modules (Go 1.11)
Diffstat (limited to 'vendor/google.golang.org/appengine/delay/delay.go')
-rw-r--r-- | vendor/google.golang.org/appengine/delay/delay.go | 295 |
1 files changed, 0 insertions, 295 deletions
diff --git a/vendor/google.golang.org/appengine/delay/delay.go b/vendor/google.golang.org/appengine/delay/delay.go deleted file mode 100644 index 52915a4..0000000 --- a/vendor/google.golang.org/appengine/delay/delay.go +++ /dev/null @@ -1,295 +0,0 @@ -// Copyright 2011 Google Inc. All rights reserved. -// Use of this source code is governed by the Apache 2.0 -// license that can be found in the LICENSE file. - -/* -Package delay provides a way to execute code outside the scope of a -user request by using the taskqueue API. - -To declare a function that may be executed later, call Func -in a top-level assignment context, passing it an arbitrary string key -and a function whose first argument is of type context.Context. -The key is used to look up the function so it can be called later. - var laterFunc = delay.Func("key", myFunc) -It is also possible to use a function literal. - var laterFunc = delay.Func("key", func(c context.Context, x string) { - // ... - }) - -To call a function, invoke its Call method. - laterFunc.Call(c, "something") -A function may be called any number of times. If the function has any -return arguments, and the last one is of type error, the function may -return a non-nil error to signal that the function should be retried. - -The arguments to functions may be of any type that is encodable by the gob -package. If an argument is of interface type, it is the client's responsibility -to register with the gob package whatever concrete type may be passed for that -argument; see http://golang.org/pkg/gob/#Register for details. - -Any errors during initialization or execution of a function will be -logged to the application logs. Error logs that occur during initialization will -be associated with the request that invoked the Call method. - -The state of a function invocation that has not yet successfully -executed is preserved by combining the file name in which it is declared -with the string key that was passed to the Func function. Updating an app -with pending function invocations is safe as long as the relevant -functions have the (filename, key) combination preserved. - -The delay package uses the Task Queue API to create tasks that call the -reserved application path "/_ah/queue/go/delay". -This path must not be marked as "login: required" in app.yaml; -it must be marked as "login: admin" or have no access restriction. -*/ -package delay // import "google.golang.org/appengine/delay" - -import ( - "bytes" - "encoding/gob" - "errors" - "fmt" - "net/http" - "reflect" - "runtime" - - "golang.org/x/net/context" - - "google.golang.org/appengine" - "google.golang.org/appengine/log" - "google.golang.org/appengine/taskqueue" -) - -// Function represents a function that may have a delayed invocation. -type Function struct { - fv reflect.Value // Kind() == reflect.Func - key string - err error // any error during initialization -} - -const ( - // The HTTP path for invocations. - path = "/_ah/queue/go/delay" - // Use the default queue. - queue = "" -) - -type contextKey int - -var ( - // registry of all delayed functions - funcs = make(map[string]*Function) - - // precomputed types - errorType = reflect.TypeOf((*error)(nil)).Elem() - - // errors - errFirstArg = errors.New("first argument must be context.Context") - errOutsideDelayFunc = errors.New("request headers are only available inside a delay.Func") - - // context keys - headersContextKey contextKey = 0 -) - -// Func declares a new Function. The second argument must be a function with a -// first argument of type context.Context. -// This function must be called at program initialization time. That means it -// must be called in a global variable declaration or from an init function. -// This restriction is necessary because the instance that delays a function -// call may not be the one that executes it. Only the code executed at program -// initialization time is guaranteed to have been run by an instance before it -// receives a request. -func Func(key string, i interface{}) *Function { - f := &Function{fv: reflect.ValueOf(i)} - - // Derive unique, somewhat stable key for this func. - _, file, _, _ := runtime.Caller(1) - f.key = file + ":" + key - - t := f.fv.Type() - if t.Kind() != reflect.Func { - f.err = errors.New("not a function") - return f - } - if t.NumIn() == 0 || !isContext(t.In(0)) { - f.err = errFirstArg - return f - } - - // Register the function's arguments with the gob package. - // This is required because they are marshaled inside a []interface{}. - // gob.Register only expects to be called during initialization; - // that's fine because this function expects the same. - for i := 0; i < t.NumIn(); i++ { - // Only concrete types may be registered. If the argument has - // interface type, the client is resposible for registering the - // concrete types it will hold. - if t.In(i).Kind() == reflect.Interface { - continue - } - gob.Register(reflect.Zero(t.In(i)).Interface()) - } - - if old := funcs[f.key]; old != nil { - old.err = fmt.Errorf("multiple functions registered for %s in %s", key, file) - } - funcs[f.key] = f - return f -} - -type invocation struct { - Key string - Args []interface{} -} - -// Call invokes a delayed function. -// err := f.Call(c, ...) -// is equivalent to -// t, _ := f.Task(...) -// _, err := taskqueue.Add(c, t, "") -func (f *Function) Call(c context.Context, args ...interface{}) error { - t, err := f.Task(args...) - if err != nil { - return err - } - _, err = taskqueueAdder(c, t, queue) - return err -} - -// Task creates a Task that will invoke the function. -// Its parameters may be tweaked before adding it to a queue. -// Users should not modify the Path or Payload fields of the returned Task. -func (f *Function) Task(args ...interface{}) (*taskqueue.Task, error) { - if f.err != nil { - return nil, fmt.Errorf("delay: func is invalid: %v", f.err) - } - - nArgs := len(args) + 1 // +1 for the context.Context - ft := f.fv.Type() - minArgs := ft.NumIn() - if ft.IsVariadic() { - minArgs-- - } - if nArgs < minArgs { - return nil, fmt.Errorf("delay: too few arguments to func: %d < %d", nArgs, minArgs) - } - if !ft.IsVariadic() && nArgs > minArgs { - return nil, fmt.Errorf("delay: too many arguments to func: %d > %d", nArgs, minArgs) - } - - // Check arg types. - for i := 1; i < nArgs; i++ { - at := reflect.TypeOf(args[i-1]) - var dt reflect.Type - if i < minArgs { - // not a variadic arg - dt = ft.In(i) - } else { - // a variadic arg - dt = ft.In(minArgs).Elem() - } - // nil arguments won't have a type, so they need special handling. - if at == nil { - // nil interface - switch dt.Kind() { - case reflect.Chan, reflect.Func, reflect.Interface, reflect.Map, reflect.Ptr, reflect.Slice: - continue // may be nil - } - return nil, fmt.Errorf("delay: argument %d has wrong type: %v is not nilable", i, dt) - } - switch at.Kind() { - case reflect.Chan, reflect.Func, reflect.Interface, reflect.Map, reflect.Ptr, reflect.Slice: - av := reflect.ValueOf(args[i-1]) - if av.IsNil() { - // nil value in interface; not supported by gob, so we replace it - // with a nil interface value - args[i-1] = nil - } - } - if !at.AssignableTo(dt) { - return nil, fmt.Errorf("delay: argument %d has wrong type: %v is not assignable to %v", i, at, dt) - } - } - - inv := invocation{ - Key: f.key, - Args: args, - } - - buf := new(bytes.Buffer) - if err := gob.NewEncoder(buf).Encode(inv); err != nil { - return nil, fmt.Errorf("delay: gob encoding failed: %v", err) - } - - return &taskqueue.Task{ - Path: path, - Payload: buf.Bytes(), - }, nil -} - -// Request returns the special task-queue HTTP request headers for the current -// task queue handler. Returns an error if called from outside a delay.Func. -func RequestHeaders(c context.Context) (*taskqueue.RequestHeaders, error) { - if ret, ok := c.Value(headersContextKey).(*taskqueue.RequestHeaders); ok { - return ret, nil - } - return nil, errOutsideDelayFunc -} - -var taskqueueAdder = taskqueue.Add // for testing - -func init() { - http.HandleFunc(path, func(w http.ResponseWriter, req *http.Request) { - runFunc(appengine.NewContext(req), w, req) - }) -} - -func runFunc(c context.Context, w http.ResponseWriter, req *http.Request) { - defer req.Body.Close() - - c = context.WithValue(c, headersContextKey, taskqueue.ParseRequestHeaders(req.Header)) - - var inv invocation - if err := gob.NewDecoder(req.Body).Decode(&inv); err != nil { - log.Errorf(c, "delay: failed decoding task payload: %v", err) - log.Warningf(c, "delay: dropping task") - return - } - - f := funcs[inv.Key] - if f == nil { - log.Errorf(c, "delay: no func with key %q found", inv.Key) - log.Warningf(c, "delay: dropping task") - return - } - - ft := f.fv.Type() - in := []reflect.Value{reflect.ValueOf(c)} - for _, arg := range inv.Args { - var v reflect.Value - if arg != nil { - v = reflect.ValueOf(arg) - } else { - // Task was passed a nil argument, so we must construct - // the zero value for the argument here. - n := len(in) // we're constructing the nth argument - var at reflect.Type - if !ft.IsVariadic() || n < ft.NumIn()-1 { - at = ft.In(n) - } else { - at = ft.In(ft.NumIn() - 1).Elem() - } - v = reflect.Zero(at) - } - in = append(in, v) - } - out := f.fv.Call(in) - - if n := ft.NumOut(); n > 0 && ft.Out(n-1) == errorType { - if errv := out[n-1]; !errv.IsNil() { - log.Errorf(c, "delay: func failed (will retry): %v", errv.Interface()) - w.WriteHeader(http.StatusInternalServerError) - return - } - } -} |