mirrored from https://chromium.googlesource.com/infra/luci/luci-go
-
Notifications
You must be signed in to change notification settings - Fork 43
/
graph.go
289 lines (247 loc) · 7.92 KB
/
graph.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
// Copyright 2020 The LUCI 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 invocations
import (
"bytes"
"context"
"fmt"
"sync"
"time"
"cloud.google.com/go/spanner"
"github.com/gomodule/redigo/redis"
"golang.org/x/sync/errgroup"
"golang.org/x/sync/semaphore"
"go.chromium.org/luci/common/errors"
"go.chromium.org/luci/common/logging"
"go.chromium.org/luci/common/trace"
"go.chromium.org/luci/server/redisconn"
"go.chromium.org/luci/server/span"
"go.chromium.org/luci/resultdb/internal/spanutil"
)
// MaxNodes is the maximum number of invocation nodes that ResultDB
// can operate on at a time.
const MaxNodes = 10000
// reachCacheExpiration is expiration duration of ReachCache.
// It is more important to have *some* expiration; the value itself matters less
// because Redis evicts LRU keys only with *some* expiration set,
// see volatile-lru policy: https://redis.io/topics/lru-cache
const reachCacheExpiration = 30 * 24 * time.Hour // 30 days
// InclusionKey returns a spanner key for an Inclusion row.
func InclusionKey(including, included ID) spanner.Key {
return spanner.Key{including.RowID(), included.RowID()}
}
// ReadIncluded reads ids of included invocations.
func ReadIncluded(ctx context.Context, id ID) (IDSet, error) {
var ret IDSet
var b spanutil.Buffer
err := span.Read(ctx, "IncludedInvocations", id.Key().AsPrefix(), []string{"IncludedInvocationId"}).Do(func(row *spanner.Row) error {
var included ID
if err := b.FromSpanner(row, &included); err != nil {
return err
}
if ret == nil {
ret = make(IDSet)
}
ret.Add(included)
return nil
})
if err != nil {
return nil, err
}
return ret, nil
}
// TooManyTag set in an error indicates that too many invocations
// matched a condition.
var TooManyTag = errors.BoolTag{
Key: errors.NewTagKey("too many matching invocations matched the condition"),
}
// Reachable returns all invocations reachable from roots along the inclusion
// edges.
// May return an appstatus-annotated error.
func Reachable(ctx context.Context, roots IDSet) (IDSet, error) {
return reachable(ctx, roots, true)
}
// ReachableSkipRootCache is similar to Reachable, but it ignores cache
// for the roots.
//
// Useful to keep cache-hit stats high in cases where the roots are known not to
// have cache.
func ReachableSkipRootCache(ctx context.Context, roots IDSet) (IDSet, error) {
return reachable(ctx, roots, false)
}
func reachable(ctx context.Context, roots IDSet, useRootCache bool) (reachable IDSet, err error) {
ctx, ts := trace.StartSpan(ctx, "resultdb.readReachableInvocations")
defer func() { ts.End(err) }()
eg, ctx := errgroup.WithContext(ctx)
defer eg.Wait()
tooMany := func() error {
return errors.Reason("more than %d invocations match", MaxNodes).Tag(TooManyTag).Err()
}
reachable = make(IDSet, len(roots))
var mu sync.Mutex
spanSem := semaphore.NewWeighted(64) // limits Spanner RPC concurrency.
var visit func(id ID, useCache bool) error
visit = func(id ID, useCache bool) error {
mu.Lock()
defer mu.Unlock()
// Check if we already started/finished fetching this invocation.
if reachable.Has(id) {
return nil
}
// Consider fetching a new invocation.
if len(reachable) == MaxNodes {
return tooMany()
}
// Mark the invocation as being processed.
reachable.Add(id)
// Concurrently fetch the inclusions without a lock.
eg.Go(func() error {
if err := ctx.Err(); err != nil {
return err
}
if useCache {
// First check the cache.
switch ids, err := ReachCache(id).Read(ctx); {
case err == redisconn.ErrNotConfigured || err == ErrUnknownReach:
// Ignore this error.
case err != nil:
logging.Warningf(ctx, "ReachCache: failed to read %s: %s", id, err)
default:
// Cache hit. Copy the results to `reachable` and exit without
// recursion.
mu.Lock()
defer mu.Unlock()
reachable.Union(ids)
if len(reachable) > MaxNodes {
return tooMany()
}
return nil
}
// Cache miss. => Read from Spanner.
}
if err := spanSem.Acquire(ctx, 1); err != nil {
return err
}
included, err := ReadIncluded(ctx, id)
spanSem.Release(1)
if err != nil {
return errors.Annotate(err, "failed to read inclusions of %s", id.Name()).Err()
}
for id := range included {
// Always use cache for children.
if err := visit(id, true); err != nil {
return err
}
}
return nil
})
return nil
}
// Trigger fetching by requesting all roots.
for id := range roots {
if err := visit(id, useRootCache); err != nil {
return nil, err
}
}
// Wait for the entire graph to be fetched.
if err := eg.Wait(); err != nil {
return nil, err
}
logging.Debugf(ctx, "%d invocations are reachable from %s", len(reachable), roots.Names())
return reachable, nil
}
// ReachCache is a cache of all invocations reachable from the given
// invocation, stored in Redis. The cached set is either correct or absent.
//
// The cache must be written only after the set of reachable invocations
// becomes immutable, i.e. when the including invocation is finalized.
// This is important to be able to tolerate transient Redis failures
// and avoid a situation where we failed to update the currently stored set,
// ignored the failure and then, after Redis came back online, read the
// stale set.
type ReachCache ID
// key returns the Redis key.
func (c ReachCache) key() string {
return fmt.Sprintf("reach:%s", c)
}
// Write writes the new value.
// The value does not have to include c, this is implied.
func (c ReachCache) Write(ctx context.Context, value IDSet) (err error) {
ctx, ts := trace.StartSpan(ctx, "resultdb.reachCache.write")
ts.Attribute("id", string(c))
defer func() { ts.End(err) }()
conn, err := redisconn.Get(ctx)
if err != nil {
return err
}
defer conn.Close()
key := c.key()
marshaled := &bytes.Buffer{}
for id := range value {
if id != ID(c) {
fmt.Fprintln(marshaled, id)
}
}
if marshaled.Len() == 0 {
// Redis does not support empty values. Write just "\n".
fmt.Fprintln(marshaled)
}
ts.Attribute("size", marshaled.Len())
conn.Send("SET", key, marshaled.Bytes())
conn.Send("EXPIRE", key, int(reachCacheExpiration.Seconds()))
_, err = conn.Do("")
return err
}
// TryWrite tries to write the new value. On failure, logs it.
func (c ReachCache) TryWrite(ctx context.Context, value IDSet) {
switch err := c.Write(ctx, value); {
case err == redisconn.ErrNotConfigured:
case err != nil:
logging.Warningf(ctx, "ReachCache: failed to write %s: %s", c, err)
}
}
// ErrUnknownReach is returned by ReachCache.Read if the cached value is absent.
var ErrUnknownReach = fmt.Errorf("the reachable set is unknown")
var memberSep = []byte("\n")
// Read reads the current value.
// Returns ErrUnknownReach if the value is absent.
//
// If err is nil, ids includes c, even if it was not passed in Write().
func (c ReachCache) Read(ctx context.Context) (ids IDSet, err error) {
ctx, ts := trace.StartSpan(ctx, "resultdb.reachCache.read")
ts.Attribute("id", string(c))
defer func() { ts.End(err) }()
conn, err := redisconn.Get(ctx)
if err != nil {
return nil, err
}
defer conn.Close()
members, err := redis.Bytes(conn.Do("GET", c.key()))
switch {
case err == redis.ErrNil:
return nil, ErrUnknownReach
case err != nil:
return nil, err
}
ts.Attribute("size", len(members))
split := bytes.Split(members, memberSep)
ids = make(IDSet, len(split)+1)
ids.Add(ID(c))
for _, id := range split {
if len(id) > 0 {
ids.Add(ID(id))
}
}
return ids, nil
}