forked from pingcap/tidb
/
cache.go
361 lines (318 loc) · 10.3 KB
/
cache.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
// Copyright 2021 PingCAP, Inc.
//
// 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 tables
import (
"context"
"sync/atomic"
"time"
"github.com/pingcap/errors"
"github.com/pingcap/failpoint"
"github.com/pingcap/log"
"github.com/tikv/client-go/v2/oracle"
"github.com/tikv/client-go/v2/tikv"
"github.com/twotigers93/tidb/kv"
"github.com/twotigers93/tidb/metrics"
"github.com/twotigers93/tidb/sessionctx"
"github.com/twotigers93/tidb/table"
"github.com/twotigers93/tidb/tablecodec"
"github.com/twotigers93/tidb/types"
"github.com/twotigers93/tidb/util/logutil"
"github.com/twotigers93/tidb/util/sqlexec"
"go.uber.org/zap"
)
var (
_ table.CachedTable = &cachedTable{}
)
type cachedTable struct {
TableCommon
cacheData atomic.Value
totalSize int64
// StateRemote is not thread-safe, this tokenLimit is used to keep only one visitor.
tokenLimit
}
type tokenLimit chan StateRemote
func (t tokenLimit) TakeStateRemoteHandle() StateRemote {
handle := <-t
return handle
}
func (t tokenLimit) TakeStateRemoteHandleNoWait() StateRemote {
select {
case handle := <-t:
return handle
default:
return nil
}
}
func (t tokenLimit) PutStateRemoteHandle(handle StateRemote) {
t <- handle
}
// cacheData pack the cache data and lease.
type cacheData struct {
Start uint64
Lease uint64
kv.MemBuffer
}
func leaseFromTS(ts uint64, leaseDuration time.Duration) uint64 {
physicalTime := oracle.GetTimeFromTS(ts)
lease := oracle.GoTimeToTS(physicalTime.Add(leaseDuration))
return lease
}
func newMemBuffer(store kv.Storage) (kv.MemBuffer, error) {
// Here is a trick to get a MemBuffer data, because the internal API is not exposed.
// Create a transaction with start ts 0, and take the MemBuffer out.
buffTxn, err := store.Begin(tikv.WithStartTS(0))
if err != nil {
return nil, err
}
return buffTxn.GetMemBuffer(), nil
}
func (c *cachedTable) TryReadFromCache(ts uint64, leaseDuration time.Duration) (kv.MemBuffer, bool /*loading*/) {
tmp := c.cacheData.Load()
if tmp == nil {
return nil, false
}
data := tmp.(*cacheData)
if ts >= data.Start && ts < data.Lease {
leaseTime := oracle.GetTimeFromTS(data.Lease)
nowTime := oracle.GetTimeFromTS(ts)
distance := leaseTime.Sub(nowTime)
var triggerFailpoint bool
failpoint.Inject("mockRenewLeaseABA1", func(_ failpoint.Value) {
triggerFailpoint = true
})
if distance >= 0 && distance <= leaseDuration/2 || triggerFailpoint {
if h := c.TakeStateRemoteHandleNoWait(); h != nil {
go c.renewLease(h, ts, data, leaseDuration)
}
}
// If data is not nil, but data.MemBuffer is nil, it means the data is being
// loading by a background goroutine.
return data.MemBuffer, data.MemBuffer == nil
}
return nil, false
}
// newCachedTable creates a new CachedTable Instance
func newCachedTable(tbl *TableCommon) (table.Table, error) {
ret := &cachedTable{
TableCommon: *tbl,
tokenLimit: make(chan StateRemote, 1),
}
return ret, nil
}
// Init is an extra operation for cachedTable after TableFromMeta,
// Because cachedTable need some additional parameter that can't be passed in TableFromMeta.
func (c *cachedTable) Init(exec sqlexec.SQLExecutor) error {
raw, ok := exec.(sqlExec)
if !ok {
return errors.New("Need sqlExec rather than sqlexec.SQLExecutor")
}
handle := NewStateRemote(raw)
c.PutStateRemoteHandle(handle)
return nil
}
func (c *cachedTable) loadDataFromOriginalTable(store kv.Storage) (kv.MemBuffer, uint64, int64, error) {
buffer, err := newMemBuffer(store)
if err != nil {
return nil, 0, 0, err
}
var startTS uint64
totalSize := int64(0)
ctx := kv.WithInternalSourceType(context.Background(), kv.InternalTxnCacheTable)
err = kv.RunInNewTxn(ctx, store, true, func(ctx context.Context, txn kv.Transaction) error {
prefix := tablecodec.GenTablePrefix(c.tableID)
if err != nil {
return errors.Trace(err)
}
startTS = txn.StartTS()
it, err := txn.Iter(prefix, prefix.PrefixNext())
if err != nil {
return errors.Trace(err)
}
defer it.Close()
for it.Valid() && it.Key().HasPrefix(prefix) {
key := it.Key()
value := it.Value()
err = buffer.Set(key, value)
if err != nil {
return errors.Trace(err)
}
totalSize += int64(len(key))
totalSize += int64(len(value))
err = it.Next()
if err != nil {
return errors.Trace(err)
}
}
return nil
})
if err != nil {
return nil, 0, totalSize, err
}
return buffer, startTS, totalSize, nil
}
func (c *cachedTable) UpdateLockForRead(ctx context.Context, store kv.Storage, ts uint64, leaseDuration time.Duration) {
if h := c.TakeStateRemoteHandleNoWait(); h != nil {
go c.updateLockForRead(ctx, h, store, ts, leaseDuration)
}
}
func (c *cachedTable) updateLockForRead(ctx context.Context, handle StateRemote, store kv.Storage, ts uint64, leaseDuration time.Duration) {
defer func() {
if r := recover(); r != nil {
log.Error("panic in the recoverable goroutine",
zap.Reflect("r", r),
zap.Stack("stack trace"))
}
c.PutStateRemoteHandle(handle)
}()
// Load data from original table and the update lock information.
tid := c.Meta().ID
lease := leaseFromTS(ts, leaseDuration)
succ, err := handle.LockForRead(ctx, tid, lease)
if err != nil {
log.Warn("lock cached table for read", zap.Error(err))
return
}
if succ {
c.cacheData.Store(&cacheData{
Start: ts,
Lease: lease,
MemBuffer: nil, // Async loading, this will be set later.
})
// Make the load data process async, in case that loading data takes longer the
// lease duration, then the loaded data get staled and that process repeats forever.
go func() {
start := time.Now()
mb, startTS, totalSize, err := c.loadDataFromOriginalTable(store)
metrics.LoadTableCacheDurationHistogram.Observe(time.Since(start).Seconds())
if err != nil {
log.Info("load data from table fail", zap.Error(err))
return
}
tmp := c.cacheData.Load().(*cacheData)
if tmp != nil && tmp.Start == ts {
c.cacheData.Store(&cacheData{
Start: startTS,
Lease: tmp.Lease,
MemBuffer: mb,
})
atomic.StoreInt64(&c.totalSize, totalSize)
}
}()
}
// Current status is not suitable to cache.
}
const cachedTableSizeLimit = 64 * (1 << 20)
// AddRecord implements the AddRecord method for the table.Table interface.
func (c *cachedTable) AddRecord(sctx sessionctx.Context, r []types.Datum, opts ...table.AddRecordOption) (recordID kv.Handle, err error) {
if atomic.LoadInt64(&c.totalSize) > cachedTableSizeLimit {
return nil, table.ErrOptOnCacheTable.GenWithStackByArgs("table too large")
}
txnCtxAddCachedTable(sctx, c.Meta().ID, c)
return c.TableCommon.AddRecord(sctx, r, opts...)
}
func txnCtxAddCachedTable(sctx sessionctx.Context, tid int64, handle *cachedTable) {
txnCtx := sctx.GetSessionVars().TxnCtx
if txnCtx.CachedTables == nil {
txnCtx.CachedTables = make(map[int64]interface{})
}
if _, ok := txnCtx.CachedTables[tid]; !ok {
txnCtx.CachedTables[tid] = handle
}
}
// UpdateRecord implements table.Table
func (c *cachedTable) UpdateRecord(ctx context.Context, sctx sessionctx.Context, h kv.Handle, oldData, newData []types.Datum, touched []bool) error {
// Prevent furthur writing when the table is already too large.
if atomic.LoadInt64(&c.totalSize) > cachedTableSizeLimit {
return table.ErrOptOnCacheTable.GenWithStackByArgs("table too large")
}
txnCtxAddCachedTable(sctx, c.Meta().ID, c)
return c.TableCommon.UpdateRecord(ctx, sctx, h, oldData, newData, touched)
}
// RemoveRecord implements table.Table RemoveRecord interface.
func (c *cachedTable) RemoveRecord(sctx sessionctx.Context, h kv.Handle, r []types.Datum) error {
txnCtxAddCachedTable(sctx, c.Meta().ID, c)
return c.TableCommon.RemoveRecord(sctx, h, r)
}
// TestMockRenewLeaseABA2 is used by test function TestRenewLeaseABAFailPoint.
var TestMockRenewLeaseABA2 chan struct{}
func (c *cachedTable) renewLease(handle StateRemote, ts uint64, data *cacheData, leaseDuration time.Duration) {
failpoint.Inject("mockRenewLeaseABA2", func(_ failpoint.Value) {
c.PutStateRemoteHandle(handle)
<-TestMockRenewLeaseABA2
c.TakeStateRemoteHandle()
})
defer c.PutStateRemoteHandle(handle)
tid := c.Meta().ID
lease := leaseFromTS(ts, leaseDuration)
newLease, err := handle.RenewReadLease(context.Background(), tid, data.Lease, lease)
if err != nil {
if !kv.IsTxnRetryableError(err) {
log.Warn("Renew read lease error", zap.Error(err))
}
return
}
if newLease > 0 {
c.cacheData.Store(&cacheData{
Start: data.Start,
Lease: newLease,
MemBuffer: data.MemBuffer,
})
}
failpoint.Inject("mockRenewLeaseABA2", func(_ failpoint.Value) {
TestMockRenewLeaseABA2 <- struct{}{}
})
}
const cacheTableWriteLease = 5 * time.Second
func (c *cachedTable) WriteLockAndKeepAlive(ctx context.Context, exit chan struct{}, leasePtr *uint64, wg chan error) {
writeLockLease, err := c.lockForWrite(ctx)
atomic.StoreUint64(leasePtr, writeLockLease)
wg <- err
if err != nil {
logutil.Logger(ctx).Warn("[cached table] lock for write lock fail", zap.Error(err))
return
}
t := time.NewTicker(cacheTableWriteLease / 2)
defer t.Stop()
for {
select {
case <-t.C:
if err := c.renew(ctx, leasePtr); err != nil {
logutil.Logger(ctx).Warn("[cached table] renew write lock lease fail", zap.Error(err))
return
}
case <-exit:
return
}
}
}
func (c *cachedTable) renew(ctx context.Context, leasePtr *uint64) error {
oldLease := atomic.LoadUint64(leasePtr)
physicalTime := oracle.GetTimeFromTS(oldLease)
newLease := oracle.GoTimeToTS(physicalTime.Add(cacheTableWriteLease))
h := c.TakeStateRemoteHandle()
defer c.PutStateRemoteHandle(h)
succ, err := h.RenewWriteLease(ctx, c.Meta().ID, newLease)
if err != nil {
return errors.Trace(err)
}
if succ {
atomic.StoreUint64(leasePtr, newLease)
}
return nil
}
func (c *cachedTable) lockForWrite(ctx context.Context) (uint64, error) {
handle := c.TakeStateRemoteHandle()
defer c.PutStateRemoteHandle(handle)
return handle.LockForWrite(ctx, c.Meta().ID, cacheTableWriteLease)
}