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Tweak buffer size for APK checksumming.

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Benchmark to calculate SHA256 over 1GB file:
    4K:  1529542318
    8K:  1101879125
    16K:  989211442
    32K:  783037993  ~20.8%
    64K:  742122399  ~5.2%
    128K: 723034565  ~4.2%
    256K: 716748703  ~0.8%
    512K: 718178800  ~-0.2%
    1M:   719738817

128K seems to be the sweet spot, with 256K being only marginally better and 512K is worse.

Bug: 196253439
Fixes: 196253439
Test: atest PackageManagerShellCommandTest PackageManagerShellCommandIncrementalTest IncrementalServiceTest PackageManagerServiceTest ChecksumsTest
Change-Id: I502e42652ed78f3eb843edc49d0b486552231a15
This commit is contained in:
Alex Buynytskyy
2021-08-27 14:14:03 -07:00
parent a5c57af882
commit e7e43738df
1 changed files with 9 additions and 6 deletions
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15
services/core/java/com/android/server/pm/ApkChecksums.java
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@@ -64,7 +64,6 @@ import com.android.internal.annotations.VisibleForTesting;
import com.android.internal.security.VerityUtils;
import com.android.server.pm.parsing.pkg.AndroidPackage;
import java.io.BufferedInputStream;
import java.io.ByteArrayOutputStream;
import java.io.DataInputStream;
import java.io.DataOutputStream;
@@ -724,16 +723,20 @@ public class ApkChecksums {
}
}
static final int MIN_BUFFER_SIZE = 4 * 1024;
static final int MAX_BUFFER_SIZE = 128 * 1024;
private static byte[] getApkChecksum(File file, int type) {
try (FileInputStream fis = new FileInputStream(file);
BufferedInputStream bis = new BufferedInputStream(fis)) {
byte[] dataBytes = new byte[512 * 1024];
final int bufferSize = (int) Math.max(MIN_BUFFER_SIZE,
Math.min(MAX_BUFFER_SIZE, file.length()));
try (FileInputStream fis = new FileInputStream(file)) {
final byte[] buffer = new byte[bufferSize];
int nread = 0;
final String algo = getMessageDigestAlgoForChecksumKind(type);
MessageDigest md = MessageDigest.getInstance(algo);
while ((nread = bis.read(dataBytes)) != -1) {
md.update(dataBytes, 0, nread);
while ((nread = fis.read(buffer)) != -1) {
md.update(buffer, 0, nread);
}
return md.digest();