From a3dacc07e2c08bb4ecfce7b5e6d5602273989e9c Mon Sep 17 00:00:00 2001 From: Tsz-Wo Nicholas Sze Date: Thu, 30 Oct 2014 10:58:26 -0700 Subject: [PATCH] HADOOP-11221. IdentityHashStore assumes System.identityHashCode() is non-negative. Contributed by Jinghui Wang --- hadoop-common-project/hadoop-common/CHANGES.txt | 3 +++ .../org/apache/hadoop/util/IdentityHashStore.java | 14 ++++++++------ 2 files changed, 11 insertions(+), 6 deletions(-) diff --git a/hadoop-common-project/hadoop-common/CHANGES.txt b/hadoop-common-project/hadoop-common/CHANGES.txt index 016b3b0e49..6020119498 100644 --- a/hadoop-common-project/hadoop-common/CHANGES.txt +++ b/hadoop-common-project/hadoop-common/CHANGES.txt @@ -1034,6 +1034,9 @@ Release 2.6.0 - UNRELEASED HADOOP-11250. fix endmacro of set_find_shared_library_without_version in CMakeLists (Yi Liu via Colin P. McCabe) + HADOOP-11221. IdentityHashStore assumes System.identityHashCode() is + non-negative. (Jinghui Wang via szetszwo) + Release 2.5.1 - 2014-09-05 INCOMPATIBLE CHANGES diff --git a/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/IdentityHashStore.java b/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/IdentityHashStore.java index 4209488d39..3ae4bbac65 100644 --- a/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/IdentityHashStore.java +++ b/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/IdentityHashStore.java @@ -92,9 +92,10 @@ private void realloc(int newCapacity) { } private void putInternal(Object k, Object v) { - int hash = System.identityHashCode(k); - final int numEntries = buffer.length / 2; - int index = hash % numEntries; + final int hash = System.identityHashCode(k); + final int numEntries = buffer.length >> 1; + //computing modulo with the assumption buffer.length is power of 2 + int index = hash & (numEntries-1); while (true) { if (buffer[2 * index] == null) { buffer[2 * index] = k; @@ -127,9 +128,10 @@ private int getElementIndex(K k) { if (buffer == null) { return -1; } - final int numEntries = buffer.length / 2; - int hash = System.identityHashCode(k); - int index = hash % numEntries; + final int numEntries = buffer.length >> 1; + final int hash = System.identityHashCode(k); + //computing modulo with the assumption buffer.length is power of 2 + int index = hash & (numEntries -1); int firstIndex = index; do { if (buffer[2 * index] == k) {