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
|
// Copyright 2014 Google Inc. All rights reserved.
//
// 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 com.google.devtools.build.lib.exec;
import static java.nio.charset.StandardCharsets.US_ASCII;
import com.google.common.base.Preconditions;
import com.google.common.cache.CacheBuilder;
import com.google.common.cache.CacheLoader;
import com.google.common.cache.LoadingCache;
import com.google.common.collect.Maps;
import com.google.common.io.BaseEncoding;
import com.google.devtools.build.lib.actions.ActionInput;
import com.google.devtools.build.lib.actions.ActionInputFileCache;
import com.google.devtools.build.lib.actions.DigestOfDirectoryException;
import com.google.devtools.build.lib.util.Pair;
import com.google.devtools.build.lib.vfs.FileSystem;
import com.google.devtools.build.lib.vfs.Path;
import com.google.protobuf.ByteString;
import java.io.File;
import java.io.IOException;
import java.util.Map;
import javax.annotation.Nullable;
import javax.annotation.concurrent.ThreadSafe;
/**
* An in-memory cache to ensure we do I/O for source files only once during a single build.
*
* <p>Simply maintains a two-way cached mapping from digest <--> filename that may be populated
* only once.
*/
@ThreadSafe
public class SingleBuildFileCache implements ActionInputFileCache {
private final String cwd;
private final FileSystem fs;
public SingleBuildFileCache(String cwd, FileSystem fs) {
this.fs = Preconditions.checkNotNull(fs);
this.cwd = Preconditions.checkNotNull(cwd);
}
// If we can't get the digest, we store the exception. This avoids extra file IO for files
// that are allowed to be missing, as we first check a likely non-existent content file
// first. Further we won't need to unwrap the exception in getDigest().
private final LoadingCache<ActionInput, Pair<ByteString, IOException>> pathToDigest =
CacheBuilder.newBuilder()
// We default to 10 disk read threads, but we don't expect them all to edit the map
// simultaneously.
.concurrencyLevel(8)
// Even small-ish builds, as of 11/21/2011 typically have over 10k artifacts, so it's
// unlikely that this default will adversely affect memory in most cases.
.initialCapacity(10000)
.build(new CacheLoader<ActionInput, Pair<ByteString, IOException>>() {
@Override
public Pair<ByteString, IOException> load(ActionInput input) {
Path path = null;
try {
path = fs.getPath(fullPath(input));
BaseEncoding hex = BaseEncoding.base16().lowerCase();
ByteString digest = ByteString.copyFrom(
hex.encode(path.getMD5Digest())
.getBytes(US_ASCII));
pathToBytes.put(input, path.getFileSize());
// Inject reverse mapping. Doing this unconditionally in getDigest() showed up
// as a hotspot in CPU profiling.
digestToPath.put(digest, input);
return Pair.of(digest, null);
} catch (IOException e) {
if (path != null && path.isDirectory()) {
pathToBytes.put(input, 0L);
return Pair.<ByteString, IOException>of(null, new DigestOfDirectoryException(
"Input is a directory: " + input.getExecPathString()));
}
// Put value into size map to avoid trying to read file again later.
pathToBytes.put(input, 0L);
return Pair.of(null, e);
}
}
});
private final Map<ByteString, ActionInput> digestToPath = Maps.newConcurrentMap();
private final Map<ActionInput, Long> pathToBytes = Maps.newConcurrentMap();
@Nullable
@Override
public File getFileFromDigest(ByteString digest) {
ActionInput relPath = digestToPath.get(digest);
return relPath == null ? null : new File(fullPath(relPath));
}
@Override
public long getSizeInBytes(ActionInput input) throws IOException {
// TODO(bazel-team): this only works if pathToDigest has already been called.
Long sz = pathToBytes.get(input);
if (sz != null) {
return sz;
}
Path path = fs.getPath(fullPath(input));
sz = path.getFileSize();
pathToBytes.put(input, sz);
return sz;
}
@Override
public ByteString getDigest(ActionInput input) throws IOException {
Pair<ByteString, IOException> result = pathToDigest.getUnchecked(input);
if (result.second != null) {
throw result.second;
}
return result.first;
}
@Override
public boolean contentsAvailableLocally(ByteString digest) {
return digestToPath.containsKey(digest);
}
/**
* Creates a File object that refers to fileName, if fileName is an absolute path. Otherwise,
* returns a File object that refers to the fileName appended to the (absolute) current working
* directory.
*/
private String fullPath(ActionInput input) {
String relPath = input.getExecPathString();
return relPath.startsWith("/") ? relPath : new File(cwd, relPath).getPath();
}
}
|
