system/core: remove BasicHashtable

Towards deprecation of SharedBuffer

Change-Id: Id6d1c8637583df38b6f28398b6804d9c1e96472a

1 files changed, 0 insertions, 395 deletions

diff --git a/include/utils/BasicHashtable.h b/include/utils/BasicHashtable.h
deleted file mode 100644
index cf4705954..000000000
--- a/include/utils/BasicHashtable.h
+++ /dev/null
@@ -1,395 +0,0 @@
-/*
- * 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.
- */
-
-#ifndef ANDROID_BASIC_HASHTABLE_H
-#define ANDROID_BASIC_HASHTABLE_H
-
-#include <stdint.h>
-#include <sys/types.h>
-#include <utils/TypeHelpers.h>
-
-namespace android {
-
-/* Implementation type.  Nothing to see here. */
-class BasicHashtableImpl {
-protected:
-    struct Bucket {
-        // The collision flag indicates that the bucket is part of a collision chain
-        // such that at least two entries both hash to this bucket.  When true, we
-        // may need to seek further along the chain to find the entry.
-        static const uint32_t COLLISION = 0x80000000UL;
-
-        // The present flag indicates that the bucket contains an initialized entry value.
-        static const uint32_t PRESENT   = 0x40000000UL;
-
-        // Mask for 30 bits worth of the hash code that are stored within the bucket to
-        // speed up lookups and rehashing by eliminating the need to recalculate the
-        // hash code of the entry's key.
-        static const uint32_t HASH_MASK = 0x3fffffffUL;
-
-        // Combined value that stores the collision and present flags as well as
-        // a 30 bit hash code.
-        uint32_t cookie;
-
-        // Storage for the entry begins here.
-        char entry[0];
-    };
-
-    BasicHashtableImpl(size_t entrySize, bool hasTrivialDestructor,
-            size_t minimumInitialCapacity, float loadFactor);
-    BasicHashtableImpl(const BasicHashtableImpl& other);
-    virtual ~BasicHashtableImpl();
-
-    void dispose();
-    void edit();
-    void setTo(const BasicHashtableImpl& other);
-    void clear();
-
-    ssize_t next(ssize_t index) const;
-    ssize_t find(ssize_t index, hash_t hash, const void* __restrict__ key) const;
-    size_t add(hash_t hash, const void* __restrict__ entry);
-    void removeAt(size_t index);
-    void rehash(size_t minimumCapacity, float loadFactor);
-
-    const size_t mBucketSize; // number of bytes per bucket including the entry
-    const bool mHasTrivialDestructor; // true if the entry type does not require destruction
-    size_t mCapacity;         // number of buckets that can be filled before exceeding load factor
-    float mLoadFactor;        // load factor
-    size_t mSize;             // number of elements actually in the table
-    size_t mFilledBuckets;    // number of buckets for which collision or present is true
-    size_t mBucketCount;      // number of slots in the mBuckets array
-    void* mBuckets;           // array of buckets, as a SharedBuffer
-
-    inline const Bucket& bucketAt(const void* __restrict__ buckets, size_t index) const {
-        return *reinterpret_cast<const Bucket*>(
-                static_cast<const uint8_t*>(buckets) + index * mBucketSize);
-    }
-
-    inline Bucket& bucketAt(void* __restrict__ buckets, size_t index) const {
-        return *reinterpret_cast<Bucket*>(static_cast<uint8_t*>(buckets) + index * mBucketSize);
-    }
-
-    virtual bool compareBucketKey(const Bucket& bucket, const void* __restrict__ key) const = 0;
-    virtual void initializeBucketEntry(Bucket& bucket, const void* __restrict__ entry) const = 0;
-    virtual void destroyBucketEntry(Bucket& bucket) const = 0;
-
-private:
-    void clone();
-
-    // Allocates a bucket array as a SharedBuffer.
-    void* allocateBuckets(size_t count) const;
-
-    // Releases a bucket array's associated SharedBuffer.
-    void releaseBuckets(void* __restrict__ buckets, size_t count) const;
-
-    // Destroys the contents of buckets (invokes destroyBucketEntry for each
-    // populated bucket if needed).
-    void destroyBuckets(void* __restrict__ buckets, size_t count) const;
-
-    // Copies the content of buckets (copies the cookie and invokes copyBucketEntry
-    // for each populated bucket if needed).
-    void copyBuckets(const void* __restrict__ fromBuckets,
-            void* __restrict__ toBuckets, size_t count) const;
-
-    // Determines the appropriate size of a bucket array to store a certain minimum
-    // number of entries and returns its effective capacity.
-    static void determineCapacity(size_t minimumCapacity, float loadFactor,
-            size_t* __restrict__ outBucketCount, size_t* __restrict__ outCapacity);
-
-    // Trim a hash code to 30 bits to match what we store in the bucket's cookie.
-    inline static hash_t trimHash(hash_t hash) {
-        return (hash & Bucket::HASH_MASK) ^ (hash >> 30);
-    }
-
-    // Returns the index of the first bucket that is in the collision chain
-    // for the specified hash code, given the total number of buckets.
-    // (Primary hash)
-    inline static size_t chainStart(hash_t hash, size_t count) {
-        return hash % count;
-    }
-
-    // Returns the increment to add to a bucket index to seek to the next bucket
-    // in the collision chain for the specified hash code, given the total number of buckets.
-    // (Secondary hash)
-    inline static size_t chainIncrement(hash_t hash, size_t count) {
-        return ((hash >> 7) | (hash << 25)) % (count - 1) + 1;
-    }
-
-    // Returns the index of the next bucket that is in the collision chain
-    // that is defined by the specified increment, given the total number of buckets.
-    inline static size_t chainSeek(size_t index, size_t increment, size_t count) {
-        return (index + increment) % count;
-    }
-};
-
-/*
- * A BasicHashtable stores entries that are indexed by hash code in place
- * within an array.  The basic operations are finding entries by key,
- * adding new entries and removing existing entries.
- *
- * This class provides a very limited set of operations with simple semantics.
- * It is intended to be used as a building block to construct more complex
- * and interesting data structures such as HashMap.  Think very hard before
- * adding anything extra to BasicHashtable, it probably belongs at a
- * higher level of abstraction.
- *
- * TKey: The key type.
- * TEntry: The entry type which is what is actually stored in the array.
- *
- * TKey must support the following contract:
- *     bool operator==(const TKey& other) const;  // return true if equal
- *     bool operator!=(const TKey& other) const;  // return true if unequal
- *
- * TEntry must support the following contract:
- *     const TKey& getKey() const;  // get the key from the entry
- *
- * This class supports storing entries with duplicate keys.  Of course, it can't
- * tell them apart during removal so only the first entry will be removed.
- * We do this because it means that operations like add() can't fail.
- */
-template <typename TKey, typename TEntry>
-class BasicHashtable : private BasicHashtableImpl {
-public:
-    /* Creates a hashtable with the specified minimum initial capacity.
-     * The underlying array will be created when the first entry is added.
-     *
-     * minimumInitialCapacity: The minimum initial capacity for the hashtable.
-     *     Default is 0.
-     * loadFactor: The desired load factor for the hashtable, between 0 and 1.
-     *     Default is 0.75.
-     */
-    BasicHashtable(size_t minimumInitialCapacity = 0, float loadFactor = 0.75f);
-
-    /* Copies a hashtable.
-     * The underlying storage is shared copy-on-write.
-     */
-    BasicHashtable(const BasicHashtable& other);
-
-    /* Clears and destroys the hashtable.
-     */
-    virtual ~BasicHashtable();
-
-    /* Making this hashtable a copy of the other hashtable.
-     * The underlying storage is shared copy-on-write.
-     *
-     * other: The hashtable to copy.
-     */
-    inline BasicHashtable<TKey, TEntry>& operator =(const BasicHashtable<TKey, TEntry> & other) {
-        setTo(other);
-        return *this;
-    }
-
-    /* Returns the number of entries in the hashtable.
-     */
-    inline size_t size() const {
-        return mSize;
-    }
-
-    /* Returns the capacity of the hashtable, which is the number of elements that can
-     * added to the hashtable without requiring it to be grown.
-     */
-    inline size_t capacity() const {
-        return mCapacity;
-    }
-
-    /* Returns the number of buckets that the hashtable has, which is the size of its
-     * underlying array.
-     */
-    inline size_t bucketCount() const {
-        return mBucketCount;
-    }
-
-    /* Returns the load factor of the hashtable. */
-    inline float loadFactor() const {
-        return mLoadFactor;
-    };
-
-    /* Returns a const reference to the entry at the specified index.
-     *
-     * index:   The index of the entry to retrieve.  Must be a valid index within
-     *          the bounds of the hashtable.
-     */
-    inline const TEntry& entryAt(size_t index) const {
-        return entryFor(bucketAt(mBuckets, index));
-    }
-
-    /* Returns a non-const reference to the entry at the specified index.
-     *
-     * index: The index of the entry to edit.  Must be a valid index within
-     *        the bounds of the hashtable.
-     */
-    inline TEntry& editEntryAt(size_t index) {
-        edit();
-        return entryFor(bucketAt(mBuckets, index));
-    }
-
-    /* Clears the hashtable.
-     * All entries in the hashtable are destroyed immediately.
-     * If you need to do something special with the entries in the hashtable then iterate
-     * over them and do what you need before clearing the hashtable.
-     */
-    inline void clear() {
-        BasicHashtableImpl::clear();
-    }
-
-    /* Returns the index of the next entry in the hashtable given the index of a previous entry.
-     * If the given index is -1, then returns the index of the first entry in the hashtable,
-     * if there is one, or -1 otherwise.
-     * If the given index is not -1, then returns the index of the next entry in the hashtable,
-     * in strictly increasing order, or -1 if there are none left.
-     *
-     * index:   The index of the previous entry that was iterated, or -1 to begin
-     *          iteration at the beginning of the hashtable.
-     */
-    inline ssize_t next(ssize_t index) const {
-        return BasicHashtableImpl::next(index);
-    }
-
-    /* Finds the index of an entry with the specified key.
-     * If the given index is -1, then returns the index of the first matching entry,
-     * otherwise returns the index of the next matching entry.
-     * If the hashtable contains multiple entries with keys that match the requested
-     * key, then the sequence of entries returned is arbitrary.
-     * Returns -1 if no entry was found.
-     *
-     * index:   The index of the previous entry with the specified key, or -1 to
-     *          find the first matching entry.
-     * hash:    The hashcode of the key.
-     * key:     The key.
-     */
-    inline ssize_t find(ssize_t index, hash_t hash, const TKey& key) const {
-        return BasicHashtableImpl::find(index, hash, &key);
-    }
-
-    /* Adds the entry to the hashtable.
-     * Returns the index of the newly added entry.
-     * If an entry with the same key already exists, then a duplicate entry is added.
-     * If the entry will not fit, then the hashtable's capacity is increased and
-     * its contents are rehashed.  See rehash().
-     *
-     * hash:    The hashcode of the key.
-     * entry:   The entry to add.
-     */
-    inline size_t add(hash_t hash, const TEntry& entry) {
-        return BasicHashtableImpl::add(hash, &entry);
-    }
-
-    /* Removes the entry with the specified index from the hashtable.
-     * The entry is destroyed immediately.
-     * The index must be valid.
-     *
-     * The hashtable is not compacted after an item is removed, so it is legal
-     * to continue iterating over the hashtable using next() or find().
-     *
-     * index:   The index of the entry to remove.  Must be a valid index within the
-     *          bounds of the hashtable, and it must refer to an existing entry.
-     */
-    inline void removeAt(size_t index) {
-        BasicHashtableImpl::removeAt(index);
-    }
-
-    /* Rehashes the contents of the hashtable.
-     * Grows the hashtable to at least the specified minimum capacity or the
-     * current number of elements, whichever is larger.
-     *
-     * Rehashing causes all entries to be copied and the entry indices may change.
-     * Although the hash codes are cached by the hashtable, rehashing can be an
-     * expensive operation and should be avoided unless the hashtable's size
-     * needs to be changed.
-     *
-     * Rehashing is the only way to change the capacity or load factor of the
-     * hashtable once it has been created.  It can be used to compact the
-     * hashtable by choosing a minimum capacity that is smaller than the current
-     * capacity (such as 0).
-     *
-     * minimumCapacity: The desired minimum capacity after rehashing.
-     * loadFactor: The desired load factor after rehashing.
-     */
-    inline void rehash(size_t minimumCapacity, float loadFactor) {
-        BasicHashtableImpl::rehash(minimumCapacity, loadFactor);
-    }
-
-    /* Determines whether there is room to add another entry without rehashing.
-     * When this returns true, a subsequent add() operation is guaranteed to
-     * complete without performing a rehash.
-     */
-    inline bool hasMoreRoom() const {
-        return mCapacity > mFilledBuckets;
-    }
-
-protected:
-    static inline const TEntry& entryFor(const Bucket& bucket) {
-        return reinterpret_cast<const TEntry&>(bucket.entry);
-    }
-
-    static inline TEntry& entryFor(Bucket& bucket) {
-        return reinterpret_cast<TEntry&>(bucket.entry);
-    }
-
-    virtual bool compareBucketKey(const Bucket& bucket, const void* __restrict__ key) const;
-    virtual void initializeBucketEntry(Bucket& bucket, const void* __restrict__ entry) const;
-    virtual void destroyBucketEntry(Bucket& bucket) const;
-
-private:
-    // For dumping the raw contents of a hashtable during testing.
-    friend class BasicHashtableTest;
-    inline uint32_t cookieAt(size_t index) const {
-        return bucketAt(mBuckets, index).cookie;
-    }
-};
-
-template <typename TKey, typename TEntry>
-BasicHashtable<TKey, TEntry>::BasicHashtable(size_t minimumInitialCapacity, float loadFactor) :
-        BasicHashtableImpl(sizeof(TEntry), traits<TEntry>::has_trivial_dtor,
-                minimumInitialCapacity, loadFactor) {
-}
-
-template <typename TKey, typename TEntry>
-BasicHashtable<TKey, TEntry>::BasicHashtable(const BasicHashtable<TKey, TEntry>& other) :
-        BasicHashtableImpl(other) {
-}
-
-template <typename TKey, typename TEntry>
-BasicHashtable<TKey, TEntry>::~BasicHashtable() {
-    dispose();
-}
-
-template <typename TKey, typename TEntry>
-bool BasicHashtable<TKey, TEntry>::compareBucketKey(const Bucket& bucket,
-        const void* __restrict__ key) const {
-    return entryFor(bucket).getKey() == *static_cast<const TKey*>(key);
-}
-
-template <typename TKey, typename TEntry>
-void BasicHashtable<TKey, TEntry>::initializeBucketEntry(Bucket& bucket,
-        const void* __restrict__ entry) const {
-    if (!traits<TEntry>::has_trivial_copy) {
-        new (&entryFor(bucket)) TEntry(*(static_cast<const TEntry*>(entry)));
-    } else {
-        memcpy(&entryFor(bucket), entry, sizeof(TEntry));
-    }
-}
-
-template <typename TKey, typename TEntry>
-void BasicHashtable<TKey, TEntry>::destroyBucketEntry(Bucket& bucket) const {
-    if (!traits<TEntry>::has_trivial_dtor) {
-        entryFor(bucket).~TEntry();
-    }
-}
-
-}; // namespace android
-
-#endif // ANDROID_BASIC_HASHTABLE_H