Add a basic hashtable data structure, with tests!
The basic hashtable is intended to be used to support a variety
of different datastructures such as map, set, multimap,
multiset, linkedmap, generationcache, etc.
Consequently its interface is fairly primitive.
The basic hashtable supports copy-on-write style functionality
using SharedBuffer.
The change introduces a simple generic function in TypeHelpers for
specifying hash functions. The idea is to add template
specializations of hash_type<T> next to the relevant data structures
such as String8, String16, sp<T>, etc.
Change-Id: I2c479229e9d4527b4fbfe3b8b04776a2fd32c973
diff --git a/libs/utils/tests/BasicHashtable_test.cpp b/libs/utils/tests/BasicHashtable_test.cpp
new file mode 100644
index 0000000..764082d
--- /dev/null
+++ b/libs/utils/tests/BasicHashtable_test.cpp
@@ -0,0 +1,577 @@
+/*
+ * Copyright (C) 2011 The Android Open Source Project
+ *
+ * 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.
+ */
+
+#define LOG_TAG "BasicHashtable_test"
+
+#include <utils/BasicHashtable.h>
+#include <cutils/log.h>
+#include <gtest/gtest.h>
+#include <unistd.h>
+
+namespace android {
+
+typedef int SimpleKey;
+typedef int SimpleValue;
+typedef key_value_pair_t<SimpleKey, SimpleValue> SimpleEntry;
+typedef BasicHashtable<SimpleKey, SimpleEntry> SimpleHashtable;
+
+struct ComplexKey {
+ int k;
+
+ explicit ComplexKey(int k) : k(k) {
+ instanceCount += 1;
+ }
+
+ ComplexKey(const ComplexKey& other) : k(other.k) {
+ instanceCount += 1;
+ }
+
+ ~ComplexKey() {
+ instanceCount -= 1;
+ }
+
+ bool operator ==(const ComplexKey& other) const {
+ return k == other.k;
+ }
+
+ bool operator !=(const ComplexKey& other) const {
+ return k != other.k;
+ }
+
+ static ssize_t instanceCount;
+};
+
+ssize_t ComplexKey::instanceCount = 0;
+
+template<> inline hash_t hash_type(const ComplexKey& value) {
+ return hash_type(value.k);
+}
+
+struct ComplexValue {
+ int v;
+
+ explicit ComplexValue(int v) : v(v) {
+ instanceCount += 1;
+ }
+
+ ComplexValue(const ComplexValue& other) : v(other.v) {
+ instanceCount += 1;
+ }
+
+ ~ComplexValue() {
+ instanceCount -= 1;
+ }
+
+ static ssize_t instanceCount;
+};
+
+ssize_t ComplexValue::instanceCount = 0;
+
+typedef key_value_pair_t<ComplexKey, ComplexValue> ComplexEntry;
+typedef BasicHashtable<ComplexKey, ComplexEntry> ComplexHashtable;
+
+class BasicHashtableTest : public testing::Test {
+protected:
+ virtual void SetUp() {
+ ComplexKey::instanceCount = 0;
+ ComplexValue::instanceCount = 0;
+ }
+
+ virtual void TearDown() {
+ ASSERT_NO_FATAL_FAILURE(assertInstanceCount(0, 0));
+ }
+
+ void assertInstanceCount(ssize_t keys, ssize_t values) {
+ if (keys != ComplexKey::instanceCount || values != ComplexValue::instanceCount) {
+ FAIL() << "Expected " << keys << " keys and " << values << " values "
+ "but there were actually " << ComplexKey::instanceCount << " keys and "
+ << ComplexValue::instanceCount << " values";
+ }
+ }
+
+public:
+ template <typename TKey, typename TEntry>
+ static void cookieAt(const BasicHashtable<TKey, TEntry>& h, size_t index,
+ bool* collision, bool* present, hash_t* hash) {
+ uint32_t cookie = h.cookieAt(index);
+ *collision = cookie & BasicHashtable<TKey, TEntry>::Bucket::COLLISION;
+ *present = cookie & BasicHashtable<TKey, TEntry>::Bucket::PRESENT;
+ *hash = cookie & BasicHashtable<TKey, TEntry>::Bucket::HASH_MASK;
+ }
+
+ template <typename TKey, typename TEntry>
+ static const void* getBuckets(const BasicHashtable<TKey, TEntry>& h) {
+ return h.mBuckets;
+ }
+};
+
+template <typename TKey, typename TValue>
+static size_t add(BasicHashtable<TKey, key_value_pair_t<TKey, TValue> >& h,
+ const TKey& key, const TValue& value) {
+ return h.add(hash_type(key), key_value_pair_t<TKey, TValue>(key, value));
+}
+
+template <typename TKey, typename TValue>
+static ssize_t find(BasicHashtable<TKey, key_value_pair_t<TKey, TValue> >& h,
+ ssize_t index, const TKey& key) {
+ return h.find(index, hash_type(key), key);
+}
+
+template <typename TKey, typename TValue>
+static bool remove(BasicHashtable<TKey, key_value_pair_t<TKey, TValue> >& h,
+ const TKey& key) {
+ ssize_t index = find(h, -1, key);
+ if (index >= 0) {
+ h.removeAt(index);
+ return true;
+ }
+ return false;
+}
+
+template <typename TEntry>
+static void getKeyValue(const TEntry& entry, int* key, int* value);
+
+template <> void getKeyValue(const SimpleEntry& entry, int* key, int* value) {
+ *key = entry.key;
+ *value = entry.value;
+}
+
+template <> void getKeyValue(const ComplexEntry& entry, int* key, int* value) {
+ *key = entry.key.k;
+ *value = entry.value.v;
+}
+
+template <typename TKey, typename TValue>
+static void dump(BasicHashtable<TKey, key_value_pair_t<TKey, TValue> >& h) {
+ LOGD("hashtable %p, size=%u, capacity=%u, bucketCount=%u",
+ &h, h.size(), h.capacity(), h.bucketCount());
+ for (size_t i = 0; i < h.bucketCount(); i++) {
+ bool collision, present;
+ hash_t hash;
+ BasicHashtableTest::cookieAt(h, i, &collision, &present, &hash);
+ if (present) {
+ int key, value;
+ getKeyValue(h.entryAt(i), &key, &value);
+ LOGD(" [%3u] = collision=%d, present=%d, hash=0x%08x, key=%3d, value=%3d, "
+ "hash_type(key)=0x%08x",
+ i, collision, present, hash, key, value, hash_type(key));
+ } else {
+ LOGD(" [%3u] = collision=%d, present=%d",
+ i, collision, present);
+ }
+ }
+}
+
+TEST_F(BasicHashtableTest, DefaultConstructor_WithDefaultProperties) {
+ SimpleHashtable h;
+
+ EXPECT_EQ(0U, h.size());
+ EXPECT_EQ(3U, h.capacity());
+ EXPECT_EQ(5U, h.bucketCount());
+ EXPECT_EQ(0.75f, h.loadFactor());
+}
+
+TEST_F(BasicHashtableTest, Constructor_WithNonUnityLoadFactor) {
+ SimpleHashtable h(52, 0.8f);
+
+ EXPECT_EQ(0U, h.size());
+ EXPECT_EQ(77U, h.capacity());
+ EXPECT_EQ(97U, h.bucketCount());
+ EXPECT_EQ(0.8f, h.loadFactor());
+}
+
+TEST_F(BasicHashtableTest, Constructor_WithUnityLoadFactorAndExactCapacity) {
+ SimpleHashtable h(46, 1.0f);
+
+ EXPECT_EQ(0U, h.size());
+ EXPECT_EQ(46U, h.capacity()); // must be one less than bucketCount because loadFactor == 1.0f
+ EXPECT_EQ(47U, h.bucketCount());
+ EXPECT_EQ(1.0f, h.loadFactor());
+}
+
+TEST_F(BasicHashtableTest, Constructor_WithUnityLoadFactorAndInexactCapacity) {
+ SimpleHashtable h(42, 1.0f);
+
+ EXPECT_EQ(0U, h.size());
+ EXPECT_EQ(46U, h.capacity()); // must be one less than bucketCount because loadFactor == 1.0f
+ EXPECT_EQ(47U, h.bucketCount());
+ EXPECT_EQ(1.0f, h.loadFactor());
+}
+
+TEST_F(BasicHashtableTest, FindAddFindRemoveFind_OneEntry) {
+ SimpleHashtable h;
+ ssize_t index = find(h, -1, 8);
+ ASSERT_EQ(-1, index);
+
+ index = add(h, 8, 1);
+ ASSERT_EQ(1U, h.size());
+
+ ASSERT_EQ(index, find(h, -1, 8));
+ ASSERT_EQ(8, h.entryAt(index).key);
+ ASSERT_EQ(1, h.entryAt(index).value);
+
+ index = find(h, index, 8);
+ ASSERT_EQ(-1, index);
+
+ ASSERT_TRUE(remove(h, 8));
+ ASSERT_EQ(0U, h.size());
+
+ index = find(h, -1, 8);
+ ASSERT_EQ(-1, index);
+}
+
+TEST_F(BasicHashtableTest, FindAddFindRemoveFind_MultipleEntryWithUniqueKey) {
+ const size_t N = 11;
+
+ SimpleHashtable h;
+ for (size_t i = 0; i < N; i++) {
+ ssize_t index = find(h, -1, int(i));
+ ASSERT_EQ(-1, index);
+
+ index = add(h, int(i), int(i * 10));
+ ASSERT_EQ(i + 1, h.size());
+
+ ASSERT_EQ(index, find(h, -1, int(i)));
+ ASSERT_EQ(int(i), h.entryAt(index).key);
+ ASSERT_EQ(int(i * 10), h.entryAt(index).value);
+
+ index = find(h, index, int(i));
+ ASSERT_EQ(-1, index);
+ }
+
+ for (size_t i = N; --i > 0; ) {
+ ASSERT_TRUE(remove(h, int(i))) << "i = " << i;
+ ASSERT_EQ(i, h.size());
+
+ ssize_t index = find(h, -1, int(i));
+ ASSERT_EQ(-1, index);
+ }
+}
+
+TEST_F(BasicHashtableTest, FindAddFindRemoveFind_MultipleEntryWithDuplicateKey) {
+ const size_t N = 11;
+ const int K = 1;
+
+ SimpleHashtable h;
+ for (size_t i = 0; i < N; i++) {
+ ssize_t index = find(h, -1, K);
+ if (i == 0) {
+ ASSERT_EQ(-1, index);
+ } else {
+ ASSERT_NE(-1, index);
+ }
+
+ add(h, K, int(i));
+ ASSERT_EQ(i + 1, h.size());
+
+ index = -1;
+ int values = 0;
+ for (size_t j = 0; j <= i; j++) {
+ index = find(h, index, K);
+ ASSERT_GE(index, 0);
+ ASSERT_EQ(K, h.entryAt(index).key);
+ values |= 1 << h.entryAt(index).value;
+ }
+ ASSERT_EQ(values, (1 << (i + 1)) - 1);
+
+ index = find(h, index, K);
+ ASSERT_EQ(-1, index);
+ }
+
+ for (size_t i = N; --i > 0; ) {
+ ASSERT_TRUE(remove(h, K)) << "i = " << i;
+ ASSERT_EQ(i, h.size());
+
+ ssize_t index = -1;
+ for (size_t j = 0; j < i; j++) {
+ index = find(h, index, K);
+ ASSERT_GE(index, 0);
+ ASSERT_EQ(K, h.entryAt(index).key);
+ }
+
+ index = find(h, index, K);
+ ASSERT_EQ(-1, index);
+ }
+}
+
+TEST_F(BasicHashtableTest, Clear_WhenAlreadyEmpty_DoesNothing) {
+ SimpleHashtable h;
+ h.clear();
+
+ EXPECT_EQ(0U, h.size());
+ EXPECT_EQ(3U, h.capacity());
+ EXPECT_EQ(5U, h.bucketCount());
+ EXPECT_EQ(0.75f, h.loadFactor());
+}
+
+TEST_F(BasicHashtableTest, Clear_AfterElementsAdded_RemovesThem) {
+ SimpleHashtable h;
+ add(h, 0, 0);
+ add(h, 1, 0);
+ h.clear();
+
+ EXPECT_EQ(0U, h.size());
+ EXPECT_EQ(3U, h.capacity());
+ EXPECT_EQ(5U, h.bucketCount());
+ EXPECT_EQ(0.75f, h.loadFactor());
+}
+
+TEST_F(BasicHashtableTest, Clear_AfterElementsAdded_DestroysThem) {
+ ComplexHashtable h;
+ add(h, ComplexKey(0), ComplexValue(0));
+ add(h, ComplexKey(1), ComplexValue(0));
+ ASSERT_NO_FATAL_FAILURE(assertInstanceCount(2, 2));
+
+ h.clear();
+ ASSERT_NO_FATAL_FAILURE(assertInstanceCount(0, 0));
+
+ EXPECT_EQ(0U, h.size());
+ EXPECT_EQ(3U, h.capacity());
+ EXPECT_EQ(5U, h.bucketCount());
+ EXPECT_EQ(0.75f, h.loadFactor());
+}
+
+TEST_F(BasicHashtableTest, Remove_AfterElementsAdded_DestroysThem) {
+ ComplexHashtable h;
+ add(h, ComplexKey(0), ComplexValue(0));
+ add(h, ComplexKey(1), ComplexValue(0));
+ ASSERT_NO_FATAL_FAILURE(assertInstanceCount(2, 2));
+
+ ASSERT_TRUE(remove(h, ComplexKey(0)));
+ ASSERT_NO_FATAL_FAILURE(assertInstanceCount(1, 1));
+
+ ASSERT_TRUE(remove(h, ComplexKey(1)));
+ ASSERT_NO_FATAL_FAILURE(assertInstanceCount(0, 0));
+
+ EXPECT_EQ(0U, h.size());
+ EXPECT_EQ(3U, h.capacity());
+ EXPECT_EQ(5U, h.bucketCount());
+ EXPECT_EQ(0.75f, h.loadFactor());
+}
+
+TEST_F(BasicHashtableTest, Destructor_AfterElementsAdded_DestroysThem) {
+ {
+ ComplexHashtable h;
+ add(h, ComplexKey(0), ComplexValue(0));
+ add(h, ComplexKey(1), ComplexValue(0));
+ ASSERT_NO_FATAL_FAILURE(assertInstanceCount(2, 2));
+ } // h is destroyed here
+
+ ASSERT_NO_FATAL_FAILURE(assertInstanceCount(0, 0));
+}
+
+TEST_F(BasicHashtableTest, Next_WhenEmpty_ReturnsMinusOne) {
+ SimpleHashtable h;
+
+ ASSERT_EQ(-1, h.next(-1));
+}
+
+TEST_F(BasicHashtableTest, Next_WhenNonEmpty_IteratesOverAllEntries) {
+ const int N = 88;
+
+ SimpleHashtable h;
+ for (int i = 0; i < N; i++) {
+ add(h, i, i * 10);
+ }
+
+ bool set[N];
+ memset(set, 0, sizeof(bool) * N);
+ int count = 0;
+ for (ssize_t index = -1; (index = h.next(index)) != -1; ) {
+ ASSERT_GE(index, 0);
+ ASSERT_LT(size_t(index), h.bucketCount());
+
+ const SimpleEntry& entry = h.entryAt(index);
+ ASSERT_GE(entry.key, 0);
+ ASSERT_LT(entry.key, N);
+ ASSERT_EQ(false, set[entry.key]);
+ ASSERT_EQ(entry.key * 10, entry.value);
+
+ set[entry.key] = true;
+ count += 1;
+ }
+ ASSERT_EQ(N, count);
+}
+
+TEST_F(BasicHashtableTest, Add_RehashesOnDemand) {
+ SimpleHashtable h;
+ size_t initialCapacity = h.capacity();
+ size_t initialBucketCount = h.bucketCount();
+
+ for (size_t i = 0; i < initialCapacity; i++) {
+ add(h, int(i), 0);
+ }
+
+ EXPECT_EQ(initialCapacity, h.size());
+ EXPECT_EQ(initialCapacity, h.capacity());
+ EXPECT_EQ(initialBucketCount, h.bucketCount());
+
+ add(h, -1, -1);
+
+ EXPECT_EQ(initialCapacity + 1, h.size());
+ EXPECT_GT(h.capacity(), initialCapacity);
+ EXPECT_GT(h.bucketCount(), initialBucketCount);
+ EXPECT_GT(h.bucketCount(), h.capacity());
+}
+
+TEST_F(BasicHashtableTest, Rehash_WhenCapacityAndBucketCountUnchanged_DoesNothing) {
+ ComplexHashtable h;
+ add(h, ComplexKey(0), ComplexValue(0));
+ const void* oldBuckets = getBuckets(h);
+ ASSERT_NE((void*)NULL, oldBuckets);
+ ASSERT_NO_FATAL_FAILURE(assertInstanceCount(1, 1));
+
+ h.rehash(h.capacity(), h.loadFactor());
+
+ ASSERT_EQ(oldBuckets, getBuckets(h));
+ ASSERT_NO_FATAL_FAILURE(assertInstanceCount(1, 1));
+}
+
+TEST_F(BasicHashtableTest, Rehash_WhenEmptyAndHasNoBuckets_ButDoesNotAllocateBuckets) {
+ ComplexHashtable h;
+ ASSERT_EQ((void*)NULL, getBuckets(h));
+ ASSERT_NO_FATAL_FAILURE(assertInstanceCount(0, 0));
+
+ h.rehash(9, 1.0f);
+
+ EXPECT_EQ(0U, h.size());
+ EXPECT_EQ(10U, h.capacity());
+ EXPECT_EQ(11U, h.bucketCount());
+ EXPECT_EQ(1.0f, h.loadFactor());
+ EXPECT_EQ((void*)NULL, getBuckets(h));
+ ASSERT_NO_FATAL_FAILURE(assertInstanceCount(0, 0));
+}
+
+TEST_F(BasicHashtableTest, Rehash_WhenEmptyAndHasBuckets_ReleasesBucketsAndSetsCapacity) {
+ ComplexHashtable h(10);
+ add(h, ComplexKey(0), ComplexValue(0));
+ ASSERT_TRUE(remove(h, ComplexKey(0)));
+ ASSERT_NE((void*)NULL, getBuckets(h));
+ ASSERT_NO_FATAL_FAILURE(assertInstanceCount(0, 0));
+
+ h.rehash(0, 0.75f);
+
+ EXPECT_EQ(0U, h.size());
+ EXPECT_EQ(3U, h.capacity());
+ EXPECT_EQ(5U, h.bucketCount());
+ EXPECT_EQ(0.75f, h.loadFactor());
+ EXPECT_EQ((void*)NULL, getBuckets(h));
+ ASSERT_NO_FATAL_FAILURE(assertInstanceCount(0, 0));
+}
+
+TEST_F(BasicHashtableTest, Rehash_WhenLessThanCurrentCapacity_ShrinksBuckets) {
+ ComplexHashtable h(10);
+ add(h, ComplexKey(0), ComplexValue(0));
+ add(h, ComplexKey(1), ComplexValue(1));
+ const void* oldBuckets = getBuckets(h);
+ ASSERT_NO_FATAL_FAILURE(assertInstanceCount(2, 2));
+
+ h.rehash(0, 0.75f);
+
+ EXPECT_EQ(2U, h.size());
+ EXPECT_EQ(3U, h.capacity());
+ EXPECT_EQ(5U, h.bucketCount());
+ EXPECT_EQ(0.75f, h.loadFactor());
+ EXPECT_NE(oldBuckets, getBuckets(h));
+ ASSERT_NO_FATAL_FAILURE(assertInstanceCount(2, 2));
+}
+
+TEST_F(BasicHashtableTest, CopyOnWrite) {
+ ComplexHashtable h1;
+ add(h1, ComplexKey(0), ComplexValue(0));
+ add(h1, ComplexKey(1), ComplexValue(1));
+ const void* originalBuckets = getBuckets(h1);
+ ASSERT_NO_FATAL_FAILURE(assertInstanceCount(2, 2));
+ ssize_t index0 = find(h1, -1, ComplexKey(0));
+ EXPECT_GE(index0, 0);
+
+ // copy constructor acquires shared reference
+ ComplexHashtable h2(h1);
+ ASSERT_NO_FATAL_FAILURE(assertInstanceCount(2, 2));
+ ASSERT_EQ(originalBuckets, getBuckets(h2));
+ EXPECT_EQ(h1.size(), h2.size());
+ EXPECT_EQ(h1.capacity(), h2.capacity());
+ EXPECT_EQ(h1.bucketCount(), h2.bucketCount());
+ EXPECT_EQ(h1.loadFactor(), h2.loadFactor());
+ EXPECT_EQ(index0, find(h2, -1, ComplexKey(0)));
+
+ // operator= acquires shared reference
+ ComplexHashtable h3;
+ h3 = h2;
+ ASSERT_NO_FATAL_FAILURE(assertInstanceCount(2, 2));
+ ASSERT_EQ(originalBuckets, getBuckets(h3));
+ EXPECT_EQ(h1.size(), h3.size());
+ EXPECT_EQ(h1.capacity(), h3.capacity());
+ EXPECT_EQ(h1.bucketCount(), h3.bucketCount());
+ EXPECT_EQ(h1.loadFactor(), h3.loadFactor());
+ EXPECT_EQ(index0, find(h3, -1, ComplexKey(0)));
+
+ // editEntryAt copies shared contents
+ h1.editEntryAt(index0).value.v = 42;
+ ASSERT_NO_FATAL_FAILURE(assertInstanceCount(4, 4));
+ ASSERT_NE(originalBuckets, getBuckets(h1));
+ EXPECT_EQ(42, h1.entryAt(index0).value.v);
+ EXPECT_EQ(0, h2.entryAt(index0).value.v);
+ EXPECT_EQ(0, h3.entryAt(index0).value.v);
+
+ // clear releases reference to shared contents
+ h2.clear();
+ ASSERT_NO_FATAL_FAILURE(assertInstanceCount(4, 4));
+ EXPECT_EQ(0U, h2.size());
+ ASSERT_NE(originalBuckets, getBuckets(h2));
+
+ // operator= acquires shared reference, destroys unshared contents
+ h1 = h3;
+ ASSERT_NO_FATAL_FAILURE(assertInstanceCount(2, 2));
+ ASSERT_EQ(originalBuckets, getBuckets(h1));
+ EXPECT_EQ(h3.size(), h1.size());
+ EXPECT_EQ(h3.capacity(), h1.capacity());
+ EXPECT_EQ(h3.bucketCount(), h1.bucketCount());
+ EXPECT_EQ(h3.loadFactor(), h1.loadFactor());
+ EXPECT_EQ(index0, find(h1, -1, ComplexKey(0)));
+
+ // add copies shared contents
+ add(h1, ComplexKey(2), ComplexValue(2));
+ ASSERT_NO_FATAL_FAILURE(assertInstanceCount(5, 5));
+ ASSERT_NE(originalBuckets, getBuckets(h1));
+ EXPECT_EQ(3U, h1.size());
+ EXPECT_EQ(0U, h2.size());
+ EXPECT_EQ(2U, h3.size());
+
+ // remove copies shared contents
+ h1 = h3;
+ ASSERT_NO_FATAL_FAILURE(assertInstanceCount(2, 2));
+ ASSERT_EQ(originalBuckets, getBuckets(h1));
+ h1.removeAt(index0);
+ ASSERT_NO_FATAL_FAILURE(assertInstanceCount(3, 3));
+ ASSERT_NE(originalBuckets, getBuckets(h1));
+ EXPECT_EQ(1U, h1.size());
+ EXPECT_EQ(0U, h2.size());
+ EXPECT_EQ(2U, h3.size());
+
+ // rehash copies shared contents
+ h1 = h3;
+ ASSERT_NO_FATAL_FAILURE(assertInstanceCount(2, 2));
+ ASSERT_EQ(originalBuckets, getBuckets(h1));
+ h1.rehash(10, 1.0f);
+ ASSERT_NO_FATAL_FAILURE(assertInstanceCount(4, 4));
+ ASSERT_NE(originalBuckets, getBuckets(h1));
+ EXPECT_EQ(2U, h1.size());
+ EXPECT_EQ(0U, h2.size());
+ EXPECT_EQ(2U, h3.size());
+}
+
+} // namespace android