From fab5e4372a941ee4259adea9295f49dcadca26a4 Mon Sep 17 00:00:00 2001 From: Matthew Holt Date: Tue, 10 Dec 2019 14:06:35 -0700 Subject: [PATCH] core: Add godoc examples for LoadModule --- context.go | 4 +- context_test.go | 118 ++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 121 insertions(+), 1 deletion(-) create mode 100644 context_test.go diff --git a/context.go b/context.go index c95b08f5..e515cb97 100644 --- a/context.go +++ b/context.go @@ -124,7 +124,9 @@ func (ctx *Context) OnCancel(f func()) { // and store them on the same struct. Storing them on the same struct makes for // easy garbage collection when your host module is no longer needed. // -// Loaded modules have already been provisioned and validated. +// Loaded modules have already been provisioned and validated. Upon returning +// successfully, this method clears the json.RawMessage(s) in the field since +// the raw JSON is no longer needed, and this allows the GC to free up memory. func (ctx Context) LoadModule(structPointer interface{}, fieldName string) (interface{}, error) { val := reflect.ValueOf(structPointer).Elem().FieldByName(fieldName) typ := val.Type() diff --git a/context_test.go b/context_test.go new file mode 100644 index 00000000..afa10dbd --- /dev/null +++ b/context_test.go @@ -0,0 +1,118 @@ +// Copyright 2015 Matthew Holt and The Caddy 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 caddy + +import ( + "encoding/json" + "io" +) + +func ExampleContext_LoadModule() { + // this whole first part is just setting up for the example; + // note the struct tags - very important; we specify inline_key + // because that is the only way to know the module name + var ctx Context + myStruct := &struct { + // This godoc comment will appear in module documentation. + GuestModuleRaw json.RawMessage `json:"guest_module,omitempty" caddy:"namespace=example inline_key=name"` + + // this is where the decoded module will be stored; in this + // example, we pretend we need an io.Writer but it can be + // any interface type that is useful to you + guestModule io.Writer + }{ + GuestModuleRaw: json.RawMessage(`{"name":"module_name","foo":"bar"}`), + } + + // if a guest module is provided, we can load it easily + if myStruct.GuestModuleRaw != nil { + mod, err := ctx.LoadModule(myStruct, "GuestModuleRaw") + if err != nil { + // you'd want to actually handle the error here + // return fmt.Errorf("loading guest module: %v", err) + } + // mod contains the loaded and provisioned module, + // it is now ready for us to use + myStruct.guestModule = mod.(io.Writer) + } + + // use myStruct.guestModule from now on +} + +func ExampleContext_LoadModule_array() { + // this whole first part is just setting up for the example; + // note the struct tags - very important; we specify inline_key + // because that is the only way to know the module name + var ctx Context + myStruct := &struct { + // This godoc comment will appear in module documentation. + GuestModulesRaw []json.RawMessage `json:"guest_modules,omitempty" caddy:"namespace=example inline_key=name"` + + // this is where the decoded module will be stored; in this + // example, we pretend we need an io.Writer but it can be + // any interface type that is useful to you + guestModules []io.Writer + }{ + GuestModulesRaw: []json.RawMessage{ + json.RawMessage(`{"name":"module1_name","foo":"bar1"}`), + json.RawMessage(`{"name":"module2_name","foo":"bar2"}`), + }, + } + + // since our input is []json.RawMessage, the output will be []interface{} + mods, err := ctx.LoadModule(myStruct, "GuestModulesRaw") + if err != nil { + // you'd want to actually handle the error here + // return fmt.Errorf("loading guest modules: %v", err) + } + for _, mod := range mods.([]interface{}) { + myStruct.guestModules = append(myStruct.guestModules, mod.(io.Writer)) + } + + // use myStruct.guestModules from now on +} + +func ExampleContext_LoadModule_map() { + // this whole first part is just setting up for the example; + // note the struct tags - very important; we don't specify + // inline_key because the map key is the module name + var ctx Context + myStruct := &struct { + // This godoc comment will appear in module documentation. + GuestModulesRaw ModuleMap `json:"guest_modules,omitempty" caddy:"namespace=example"` + + // this is where the decoded module will be stored; in this + // example, we pretend we need an io.Writer but it can be + // any interface type that is useful to you + guestModules map[string]io.Writer + }{ + GuestModulesRaw: ModuleMap{ + "module1_name": json.RawMessage(`{"foo":"bar1"}`), + "module2_name": json.RawMessage(`{"foo":"bar2"}`), + }, + } + + // since our input is map[string]json.RawMessage, the output will be map[string]interface{} + mods, err := ctx.LoadModule(myStruct, "GuestModulesRaw") + if err != nil { + // you'd want to actually handle the error here + // return fmt.Errorf("loading guest modules: %v", err) + } + for modName, mod := range mods.(map[string]interface{}) { + myStruct.guestModules[modName] = mod.(io.Writer) + } + + // use myStruct.guestModules from now on +}