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Issue 2302743002: Interface update, per-method Contexts. (Closed)
Patch Set: Created 4 years, 3 months ago
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1 // Copyright 2015 The LUCI Authors. All rights reserved. 1 // Copyright 2015 The LUCI Authors. All rights reserved.
2 // Use of this source code is governed under the Apache License, Version 2.0 2 // Use of this source code is governed under the Apache License, Version 2.0
3 // that can be found in the LICENSE file. 3 // that can be found in the LICENSE file.
4 4
5 // Package gae provides a fakable wrapped interface for the appengine SDK's 5 // Package gae provides a fakable wrapped interface for the appengine SDK's
6 // APIs. This means that it's possible to mock all of the supported appengine 6 // APIs. This means that it's possible to mock all of the supported appengine
7 // APIs for testing (or potentially implement a different backend for them). 7 // APIs for testing (or potentially implement a different backend for them).
8 // 8 //
9 // Features 9 // Features
10 // 10 //
(...skipping 45 matching lines...) Expand 10 before | Expand all | Expand 10 after
56 // innerHandler(c, w) 56 // innerHandler(c, w)
57 // } 57 // }
58 // 58 //
59 // type CoolStruct struct { 59 // type CoolStruct struct {
60 // ID `gae:"$id"` 60 // ID `gae:"$id"`
61 // 61 //
62 // Value string 62 // Value string
63 // } 63 // }
64 // 64 //
65 // func innerHandler(c context.Context, w http.ResponseWriter) { 65 // func innerHandler(c context.Context, w http.ResponseWriter) {
66 // rds := datastore.Get(c)
67 // obj := &CoolStruct{Value: "hello"} 66 // obj := &CoolStruct{Value: "hello"}
68 // if err := rds.Put(obj); err != nil { 67 // if err := rds.Put(c, obj); err != nil {
69 // http.Error(w, err.String(), http.StatusInternalServerError) 68 // http.Error(w, err.String(), http.StatusInternalServerError)
70 // } 69 // }
71 // fmt.Fprintf(w, "I wrote: %s", ds.KeyForObj(obj)) 70 // fmt.Fprintf(w, "I wrote: %s", ds.KeyForObj(obj))
72 // } 71 // }
73 // 72 //
74 // And in your test do: 73 // And in your test do:
75 // 74 //
76 // import ( 75 // import (
77 // "testing" 76 // "testing"
78 // "fmt" 77 // "fmt"
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171 // CoolFunc(c) 170 // CoolFunc(c)
172 // } 171 // }
173 // 172 //
174 // // This is the 'testing' code 173 // // This is the 'testing' code
175 // func TestCoolFunc(t *testing.T) { 174 // func TestCoolFunc(t *testing.T) {
176 // c := memory.Use(context.Background()) 175 // c := memory.Use(context.Background())
177 // CoolFunc(c) 176 // CoolFunc(c)
178 // } 177 // }
179 // 178 //
180 // func CoolFunc(c context.Context, ...) { 179 // func CoolFunc(c context.Context, ...) {
181 // ds := datastore.Get(c) // returns a datastore.Interface object
182 // mc := memcache.Get(c) // returns a memcache.Interface object
183 // // use them here
184 //
185 // // don't pass ds/mc/etc. directly, pass the context instead. 180 // // don't pass ds/mc/etc. directly, pass the context instead.
iannucci 2016/09/16 01:01:13 this comment no longer makes sense
dnj 2016/09/16 05:44:42 Done.
186 // SomeOtherFunction(c, ...) 181 // SomeOtherFunction(c, ...)
187 // 182 //
188 // // because you might need to: 183 // // because you might need to:
189 // ds.RunInTransaction(func (c context.Context) error { 184 // ds.RunInTransaction(c, func (c context.Context) error {
190 // SomeOtherFunction(c, ...) // c contains transactional versions of ever ything 185 // SomeOtherFunction(c, ...) // c contains transactional versions of ever ything
191 // }, nil) 186 // }, nil)
192 // } 187 // }
193 // 188 //
194 // Filters 189 // Filters
195 // 190 //
196 // Each service also supports "filters". Filters are proxy objects which have 191 // Each service also supports "filters". Filters are proxy objects which have
197 // the same interface as the service they're filtering, and pass data through to 192 // the same interface as the service they're filtering, and pass data through to
198 // the previous filter in the stack. Conceptually, a filtered version of, for 193 // the previous filter in the stack. Conceptually, a filtered version of, for
199 // example, the Datastore, could look like: 194 // example, the Datastore, could look like:
200 // User code 195 // User code
201 // <count filter (counts how many times each API is called by the user)> 196 // <count filter (counts how many times each API is called by the user)>
202 // <dscache filter (attempts to use memcache as a cache for datastore)> 197 // <dscache filter (attempts to use memcache as a cache for datastore)>
203 // <count filter (counts how many times each API is actually hit)> 198 // <count filter (counts how many times each API is actually hit)>
204 // memory datastore.RawInterface implementation 199 // memory datastore.RawInterface implementation
205 // 200 //
206 // So datastore.Get would return the full stack. In code, this would look 201 // So datastore.Raw would return the full stack. In code, this would look
iannucci 2016/09/16 01:01:13 Nor does this one
dnj 2016/09/16 05:44:42 Done.
207 // like: 202 // like:
208 // func HTTPHandler(r *http.Request) { 203 // func HTTPHandler(r *http.Request) {
209 // c := prod.UseRequest(r)» » » » » » » // production datastore 204 // c := prod.UseRequest(r) // production datastore
210 // c, rawCount := count.FilterRDS(c) // add count filter 205 // c, rawCount := count.FilterRDS(c) // add count filter
211 // c = dscache.FilterRDS(c) // add dscache filter 206 // c = dscache.FilterRDS(c) // add dscache filter
212 // c, userCount := count.FilterRDS(c) // add another count filter 207 // c, userCount := count.FilterRDS(c) // add another count filter
213 // } 208 // }
214 // 209 //
215 // Filters may or may not have state, it's up to the filter itself. In the case 210 // Filters may or may not have state, it's up to the filter itself. In the case
216 // of the count filter, it returns its state from the Filter<Service> method, 211 // of the count filter, it returns its state from the Filter<Service> method,
217 // and the state can be observed to see how many times each API was invoked. 212 // and the state can be observed to see how many times each API was invoked.
218 // Since filters stack, we can compare counts from rawCount versus userCount to 213 // Since filters stack, we can compare counts from rawCount versus userCount to
219 // see how many calls to the actual real datastore went through, vs. how many 214 // see how many calls to the actual real datastore went through, vs. how many
220 // went to memcache, for example. 215 // went to memcache, for example.
221 // 216 //
222 // Note that Filters apply only to the service.RawInterface. All implementations 217 // Note that Filters apply only to the service.RawInterface. All implementations
223 // of service.Interface boil down to calls to service.RawInterface methods, but 218 // of service.Interface boil down to calls to service.RawInterface methods, but
224 // it's possible that bad calls to the service.Interface methods could return 219 // it's possible that bad calls to the service.Interface methods could return
225 // an error before ever reaching the filters or service implementation. 220 // an error before ever reaching the filters or service implementation.
226 package gae 221 package gae
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