1 /*
2 * Licensed under the Apache License, Version 2.0 (the "License");
3 * you may not use this file except in compliance with the License.
4 * You may obtain a copy of the License at
5 *
6 * http://www.apache.org/licenses/LICENSE-2.0
7 *
8 * Unless required by applicable law or agreed to in writing, software
9 * distributed under the License is distributed on an "AS IS" BASIS,
10 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
11 * See the License for the specific language governing permissions and
12 * limitations under the License.
13 */
14 package de.softwareforge.testing.postgres.embedded;
15
16 import static com.google.common.base.Preconditions.checkState;
17
18 import java.io.IOException;
19 import java.io.InputStream;
20
21 import com.google.common.hash.Hashing;
22 import com.google.common.hash.HashingInputStream;
23 import com.google.common.io.BaseEncoding;
24 import com.google.common.io.ByteStreams;
25 import edu.umd.cs.findbugs.annotations.CheckForNull;
26 import edu.umd.cs.findbugs.annotations.NonNull;
27 import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
28
29 /**
30 * Locates a native binary on the Filesystem. If necessary, it should download the binary first from the network.
31 * <p>
32 * Implementations of this class <b>must</b> implement {@link Object#hashCode()} and {@link Object#equals(Object)} and *should* implement {@link Object#toString()}.
33 */
34 public interface NativeBinaryLocator {
35
36 String INSTALL_DIRECTORY_PREFIX = "bin-";
37
38 /**
39 * Returns an input stream from which the contents of the binary archive can be read.
40 *
41 * @return An input stream. May return null.
42 * @throws IOException If the archive could not be located or read.
43 */
44 @CheckForNull
45 InputStream getInputStream() throws IOException;
46
47 /**
48 * Returns a string identifier that represents the archive returned. This identifier should be stable (same value for the same archive), even across
49 * multiple JVM invocations. The value must only contain characters that can be used as a legal file name.
50 * <p>
51 * The default implementation needs to read the full archive contents and is relatively slow. Implementations of this interface can override this method to
52 * provide a faster way to create a stable identifier based on the specific implementation.
53 * <p>
54 * The default implementation hashes the archive contents and uses it to return a stable file name.
55 *
56 * @return A stable indentifier that can be used as a file name.
57 * @throws IOException If the stream could not be read.
58 */
59 @NonNull
60 @SuppressFBWarnings("NP_NULL_ON_SOME_PATH_FROM_RETURN_VALUE") // false positive
61 default String getIdentifier() throws IOException {
62 try (InputStream installationArchive = getInputStream()) {
63 checkState(installationArchive != null, "Locator '%s' did not find a suitable archive to unpack!", toString());
64 try (HashingInputStream hashStream = new HashingInputStream(Hashing.murmur3_128(), installationArchive)) {
65 ByteStreams.exhaust(hashStream);
66 return INSTALL_DIRECTORY_PREFIX + BaseEncoding.base16().encode(hashStream.hash().asBytes());
67 }
68 }
69 }
70 }