From 1bf7d3f290ef7dbf9b4f12d15308a4d93042ac83 Mon Sep 17 00:00:00 2001 From: Shawn Pearce Date: Sun, 26 Feb 2017 11:44:51 -0800 Subject: [PATCH] SHA1: support reset() and reuse instances Allow SHA1 instances to be reused to compute another hash value, and resume caching them in ObjectInserter and PackParser. This shaves a small amount of running time off parsing git.git's pack file: before after ------ ------ 25.25s 25.55s 25.48s 25.06s 25.26s 24.94s Almost noise (small difference), but recycling the instances reduces some stress on the memory allocator finding two 80 word message block arrays needed for hashing and collision detection. Change-Id: I4af88a720e81460293bc5c5d1d3db1a831e7e228 --- .../org/eclipse/jgit/util/sha1/SHA1Test.java | 15 +++++++++ .../internal/storage/dfs/DfsInserter.java | 2 +- .../storage/file/ObjectDirectoryInserter.java | 2 +- .../org/eclipse/jgit/lib/ObjectInserter.java | 4 ++- .../eclipse/jgit/transport/PackParser.java | 5 +-- .../src/org/eclipse/jgit/util/sha1/SHA1.java | 32 +++++++++++++++---- 6 files changed, 49 insertions(+), 11 deletions(-) diff --git a/org.eclipse.jgit.test/tst/org/eclipse/jgit/util/sha1/SHA1Test.java b/org.eclipse.jgit.test/tst/org/eclipse/jgit/util/sha1/SHA1Test.java index c53080455..8642db79e 100644 --- a/org.eclipse.jgit.test/tst/org/eclipse/jgit/util/sha1/SHA1Test.java +++ b/org.eclipse.jgit.test/tst/org/eclipse/jgit/util/sha1/SHA1Test.java @@ -72,8 +72,13 @@ public class SHA1Test { s.update(new byte[] {}); ObjectId s1 = ObjectId.fromRaw(s.digest()); + s.reset(); + s.update(new byte[] {}); + ObjectId s2 = s.toObjectId(); + assertEquals(m1, s1); assertEquals(exp, s1); + assertEquals(exp, s2); } @Test @@ -89,8 +94,13 @@ public class SHA1Test { s.update(TEST1.getBytes(StandardCharsets.UTF_8)); ObjectId s1 = ObjectId.fromRaw(s.digest()); + s.reset(); + s.update(TEST1.getBytes(StandardCharsets.UTF_8)); + ObjectId s2 = s.toObjectId(); + assertEquals(m1, s1); assertEquals(exp, s1); + assertEquals(exp, s2); } @Test @@ -106,7 +116,12 @@ public class SHA1Test { s.update(TEST2.getBytes(StandardCharsets.UTF_8)); ObjectId s1 = ObjectId.fromRaw(s.digest()); + s.reset(); + s.update(TEST2.getBytes(StandardCharsets.UTF_8)); + ObjectId s2 = s.toObjectId(); + assertEquals(m1, s1); assertEquals(exp, s1); + assertEquals(exp, s2); } } diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/DfsInserter.java b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/DfsInserter.java index d3ac62650..fd72756e3 100644 --- a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/DfsInserter.java +++ b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/dfs/DfsInserter.java @@ -169,7 +169,7 @@ public class DfsInserter extends ObjectInserter { } long offset = beginObject(type, len); - SHA1 md = SHA1.newInstance(); + SHA1 md = digest(); md.update(Constants.encodedTypeString(type)); md.update((byte) ' '); md.update(Constants.encodeASCII(len)); diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/ObjectDirectoryInserter.java b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/ObjectDirectoryInserter.java index c37c4daa4..aa435bf67 100644 --- a/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/ObjectDirectoryInserter.java +++ b/org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/ObjectDirectoryInserter.java @@ -140,7 +140,7 @@ class ObjectDirectoryInserter extends ObjectInserter { return insert(type, buf, 0, actLen, createDuplicate); } else { - SHA1 md = SHA1.newInstance(); + SHA1 md = digest(); File tmp = toTemp(md, type, len, is); ObjectId id = md.toObjectId(); return insertOneObject(tmp, id, createDuplicate); diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/lib/ObjectInserter.java b/org.eclipse.jgit/src/org/eclipse/jgit/lib/ObjectInserter.java index b39603ada..ad0b3332c 100644 --- a/org.eclipse.jgit/src/org/eclipse/jgit/lib/ObjectInserter.java +++ b/org.eclipse.jgit/src/org/eclipse/jgit/lib/ObjectInserter.java @@ -177,6 +177,8 @@ public abstract class ObjectInserter implements AutoCloseable { } } + private final SHA1 hasher = SHA1.newInstance(); + /** Temporary working buffer for streaming data through. */ private byte[] tempBuffer; @@ -217,7 +219,7 @@ public abstract class ObjectInserter implements AutoCloseable { /** @return digest to help compute an ObjectId */ protected SHA1 digest() { - return SHA1.newInstance(); + return hasher.reset(); } /** diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/transport/PackParser.java b/org.eclipse.jgit/src/org/eclipse/jgit/transport/PackParser.java index 7d48f2a25..c82b3891b 100644 --- a/org.eclipse.jgit/src/org/eclipse/jgit/transport/PackParser.java +++ b/org.eclipse.jgit/src/org/eclipse/jgit/transport/PackParser.java @@ -117,6 +117,7 @@ public abstract class PackParser { private byte[] hdrBuf; + private final SHA1 objectHasher = SHA1.newInstance(); private final MutableObjectId tempObjectId; private InputStream in; @@ -665,7 +666,7 @@ public abstract class PackParser { JGitText.get().corruptionDetectedReReadingAt, Long.valueOf(visit.delta.position))); - SHA1 objectDigest = SHA1.newInstance(); + SHA1 objectDigest = objectHasher.reset(); objectDigest.update(Constants.encodedTypeString(type)); objectDigest.update((byte) ' '); objectDigest.update(Constants.encodeASCII(visit.data.length)); @@ -1023,7 +1024,7 @@ public abstract class PackParser { private void whole(final long pos, final int type, final long sz) throws IOException { - SHA1 objectDigest = SHA1.newInstance(); + SHA1 objectDigest = objectHasher.reset(); objectDigest.update(Constants.encodedTypeString(type)); objectDigest.update((byte) ' '); objectDigest.update(Constants.encodeASCII(sz)); diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/util/sha1/SHA1.java b/org.eclipse.jgit/src/org/eclipse/jgit/util/sha1/SHA1.java index 0a1dc1046..293b4ac56 100644 --- a/org.eclipse.jgit/src/org/eclipse/jgit/util/sha1/SHA1.java +++ b/org.eclipse.jgit/src/org/eclipse/jgit/util/sha1/SHA1.java @@ -63,12 +63,11 @@ public class SHA1 { return new SHA1(); } - // Magic initialization constants defined by FIPS180. - private int h0 = 0x67452301; - private int h1 = 0xEFCDAB89; - private int h2 = 0x98BADCFE; - private int h3 = 0x10325476; - private int h4 = 0xC3D2E1F0; + private int h0; + private int h1; + private int h2; + private int h3; + private int h4; private final int[] w = new int[80]; /** Buffer to accumulate partial blocks to 64 byte alignment. */ @@ -78,6 +77,27 @@ public class SHA1 { private long length; private SHA1() { + init(); + } + + /** + * Reset this instance to compute another hash. + * + * @return {@code this}. + */ + public SHA1 reset() { + init(); + length = 0; + return this; + } + + private void init() { + // Magic initialization constants defined by FIPS180. + h0 = 0x67452301; + h1 = 0xEFCDAB89; + h2 = 0x98BADCFE; + h3 = 0x10325476; + h4 = 0xC3D2E1F0; } /**