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| 1 // Copyright 2015 The Chromium Authors. All rights reserved. | |
| 2 // Use of this source code is governed by a BSD-style license that can be | |
| 3 // found in the LICENSE file. | |
| 4 | |
| 5 package memory | |
| 6 | |
| 7 import ( | |
| 8 "errors" | |
| 9 "sync" | |
| 10 | |
| 11 "github.com/luci/gae" | |
| 12 "golang.org/x/net/context" | |
| 13 ) | |
| 14 | |
| 15 type memContextObj interface { | |
| 16 sync.Locker | |
| 17 canApplyTxn(m memContextObj) bool | |
| 18 applyTxn(c context.Context, m memContextObj) | |
| 19 | |
| 20 endTxn() | |
| 21 mkTxn(*gae.DSTransactionOptions) memContextObj | |
| 22 } | |
| 23 | |
| 24 type memContext []memContextObj | |
| 25 | |
| 26 var _ = memContextObj((memContext)(nil)) | |
| 27 | |
| 28 func newMemContext() memContext { | |
| 29 return memContext{ | |
| 30 newTaskQueueData(), | |
| 31 newDataStoreData(), | |
| 32 } | |
| 33 } | |
| 34 | |
| 35 type memContextIdx int | |
| 36 | |
| 37 const ( | |
| 38 memContextTQIdx memContextIdx = iota | |
| 39 memContextDSIdx | |
| 40 ) | |
| 41 | |
| 42 func (m memContext) Get(itm memContextIdx) memContextObj { | |
| 43 return m[itm] | |
| 44 } | |
| 45 | |
| 46 func (m memContext) Lock() { | |
| 47 for _, itm := range m { | |
| 48 itm.Lock() | |
| 49 } | |
| 50 } | |
| 51 | |
| 52 func (m memContext) Unlock() { | |
| 53 for i := len(m) - 1; i >= 0; i-- { | |
| 54 m[i].Unlock() | |
| 55 } | |
| 56 } | |
| 57 | |
| 58 func (m memContext) endTxn() { | |
| 59 for _, itm := range m { | |
| 60 itm.endTxn() | |
| 61 } | |
| 62 } | |
| 63 | |
| 64 func (m memContext) mkTxn(o *gae.DSTransactionOptions) memContextObj { | |
| 65 ret := make(memContext, len(m)) | |
| 66 for i, itm := range m { | |
| 67 ret[i] = itm.mkTxn(o) | |
| 68 } | |
| 69 return ret | |
| 70 } | |
| 71 | |
| 72 func (m memContext) canApplyTxn(txnCtxObj memContextObj) bool { | |
| 73 txnCtx := txnCtxObj.(memContext) | |
| 74 for i := range m { | |
| 75 if !m[i].canApplyTxn(txnCtx[i]) { | |
| 76 return false | |
| 77 } | |
| 78 } | |
| 79 return true | |
| 80 } | |
| 81 | |
| 82 func (m memContext) applyTxn(c context.Context, txnCtxObj memContextObj) { | |
| 83 txnCtx := txnCtxObj.(memContext) | |
| 84 for i := range m { | |
| 85 m[i].applyTxn(c, txnCtx[i]) | |
| 86 } | |
| 87 } | |
| 88 | |
| 89 // Use adds implementations for the following gae interfaces to the | |
| 90 // context: | |
| 91 // * gae.Datastore | |
| 92 // * gae.TaskQueue | |
| 93 // * gae.Memcache | |
| 94 // * gae.GlobalInfo | |
| 95 // | |
| 96 // These can be retrieved with the gae.Get functions. | |
| 97 // | |
| 98 // The implementations are all backed by an in-memory implementation, and start | |
| 99 // with an empty state. | |
| 100 // | |
| 101 // Using this more than once per context.Context will cause a panic. | |
| 102 func Use(c context.Context) context.Context { | |
| 103 if c.Value(memContextKey) != nil { | |
| 104 panic(errors.New("memory.Use: called twice on the same Context")
) | |
| 105 } | |
| 106 c = context.WithValue( | |
| 107 context.WithValue(c, memContextKey, newMemContext()), | |
| 108 giContextKey, &globalInfoData{}) | |
| 109 return useTQ(useRDS(useMC(useGI(c)))) | |
| 110 } | |
| 111 | |
| 112 func cur(c context.Context) (p memContext) { | |
| 113 p, _ = c.Value(memContextKey).(memContext) | |
| 114 return | |
| 115 } | |
| 116 | |
| 117 type memContextKeyType int | |
| 118 | |
| 119 var memContextKey memContextKeyType | |
| 120 | |
| 121 // weird stuff | |
| 122 | |
| 123 // RunInTransaction is here because it's really a service-wide transaction, not | |
| 124 // just in the datastore. TaskQueue behaves differently in a transaction in | |
| 125 // a couple ways, for example. | |
| 126 // | |
| 127 // It really should have been appengine.Context.RunInTransaction(func(tc...)), | |
| 128 // but because it's not, this method is on dsImpl instead to mirror the official | |
| 129 // API. | |
| 130 // | |
| 131 // The fake implementation also differs from the real implementation because the | |
| 132 // fake TaskQueue is NOT backed by the fake Datastore. This is done to make the | |
| 133 // test-access API for TaskQueue better (instead of trying to reconstitute the | |
| 134 // state of the task queue from a bunch of datastore accesses). | |
| 135 func (d *dsImpl) RunInTransaction(f func(context.Context) error, o *gae.DSTransa
ctionOptions) error { | |
| 136 curMC := cur(d.c) | |
| 137 | |
| 138 txnMC := curMC.mkTxn(o) | |
| 139 | |
| 140 defer func() { | |
| 141 txnMC.Lock() | |
| 142 defer txnMC.Unlock() | |
| 143 | |
| 144 txnMC.endTxn() | |
| 145 }() | |
| 146 | |
| 147 if err := f(context.WithValue(d.c, memContextKey, txnMC)); err != nil { | |
| 148 return err | |
| 149 } | |
| 150 | |
| 151 txnMC.Lock() | |
| 152 defer txnMC.Unlock() | |
| 153 | |
| 154 if curMC.canApplyTxn(txnMC) { | |
| 155 curMC.applyTxn(d.c, txnMC) | |
| 156 } else { | |
| 157 return gae.ErrDSConcurrentTransaction | |
| 158 } | |
| 159 return nil | |
| 160 } | |
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