PHP底層的高效能資料結構與實作方法

PHP底層的高效能資料結構與實作方法，需要具體程式碼範例

隨著網路應用的不斷發展，PHP已經成為了一種廣泛使用的伺服器端腳本語言。然而，在大規模的Web應用中，PHP的效能問題成為了一個不容忽視的問題，許多大型網站都出現了效能瓶頸和系統崩潰的情況。

為了提升PHP的效能，我們需要了解PHP底層的高效能資料結構與實作方法。本文將介紹PHP的幾種高效能資料結構及其實作方法，並提供對應的程式碼範例，幫助讀者深入理解PHP的效能最佳化。

1. 陣列

在PHP中，陣列是最常用的資料結構之一。不過，PHP的數組實作採用了哈希表的方式，這會帶來一些效能上的開銷，特別是在對大量資料進行迭代操作時。

為了提高PHP的陣列效能，我們可以使用C語言擴充來實作。

下面是一個簡單的PHP擴充範例，該擴充實作了一個高效能的雜湊表，可以用於儲存大量的數據，並且支援各種資料類型的儲存和存取。

typedef struct {
    zend_ulong h;
    zval data;
} hashtable_entry;

typedef struct {
    hashtable_entry *table;
    zend_ulong num_entries;
    zend_ulong max_entries;
    zend_ulong rehash_pos;
    zend_ulong rehash_size;
} hashtable;

typedef struct {
    zend_object std;
    hashtable *ht;
} hash_table_object;

static zend_object *hash_table_object_new(zend_class_entry *class_type)
{
    hash_table_object *intern = 
        (hash_table_object *)ecalloc(1, sizeof(hash_table_object));
    zend_object_std_init(&intern->std, class_type);
    object_properties_init(&intern->std, class_type);
    intern->std.handlers = &hash_table_object_handlers;
    intern->ht = 
        (hashtable *)emalloc(sizeof(hashtable));
    return &intern->std;
}

static void hash_table_object_free(zend_object *object)
{
    hash_table_object *intern = 
        hash_table_object_from_obj(object);
    if (intern->ht != NULL) {
        zend_ulong i;
        for (i = 0; i < intern->ht->max_entries; i++) {
            zval_dtor(
                &intern->ht->table[i].data
            );
        }
        efree(intern->ht->table);
        efree(intern->ht);
    }
    zend_object_std_dtor(object);
}

static void hash_table_put(hash_table_object *intern, 
                           zval *key, 
                           zval *value)
{
    zend_ulong idx;
    zend_string *str_key;
    if (Z_TYPE_P(key) == IS_STRING) {
        str_key = Z_STR_P(key);
        idx = zend_inline_hash_func(
            str_key->val, str_key->len
        ) % intern->ht->max_entries;
    } else if (Z_TYPE_P(key) == IS_LONG) {
        idx = Z_LVAL_P(key) % intern->ht->max_entries;
    } else if (Z_TYPE_P(key) == IS_DOUBLE) {
        idx = zend_dval_to_lval(Z_DVAL_P(key)) % intern->ht->max_entries;
    } else if (Z_TYPE_P(key) == IS_TRUE) {
        idx = 1 % intern->ht->max_entries;
    } else {
        idx = 0;
    }
    if (Z_TYPE(intern->ht->table[idx].data) != IS_NULL) {
        zval_dtor(
            &intern->ht->table[idx].data
        );
    }
    intern->ht->table[idx].h = idx;
    ZVAL_COPY_VALUE(
        &intern->ht->table[idx].data, value
    );
}

static zval *hash_table_get(hash_table_object *intern, 
                             zval *key)
{
    zend_ulong idx;
    zend_string *str_key;
    if (Z_TYPE_P(key) == IS_STRING) {
        str_key = Z_STR_P(key);
        idx = zend_inline_hash_func(
            str_key->val, str_key->len
        ) % intern->ht->max_entries;
    } else if (Z_TYPE_P(key) == IS_LONG) {
        idx = Z_LVAL_P(key) % intern->ht->max_entries;
    } else if (Z_TYPE_P(key) == IS_DOUBLE) {
        idx = zend_dval_to_lval(Z_DVAL_P(key)) % intern->ht->max_entries;
    } else if (Z_TYPE_P(key) == IS_TRUE) {
        idx = 1 % intern->ht->max_entries;
    } else {
        idx = 0;
    }
    if (Z_TYPE(intern->ht->table[idx].data) == IS_NULL) {
        return NULL;
    } else {
        return &intern->ht->table[idx].data;
    }
}

static zend_class_entry *hash_table_class_entry;

static zend_function_entry hash_table_methods[] = {
    PHP_ME(HashTable, put, arginfo_hashtable_put, ZEND_ACC_PUBLIC)
    PHP_ME(HashTable, get, arginfo_hashtable_get, ZEND_ACC_PUBLIC)
    PHP_FE_END
};

static zend_object_handlers hash_table_object_handlers;

static void hash_table_object_init(zend_class_entry *class_type)
{
    hash_table_object_handlers = 
        *zend_get_std_object_handlers();
    hash_table_object_handlers.offset = 
        XtOffsetOf(hash_table_object, std);
    hash_table_object_handlers.free_obj = 
        hash_table_object_free;
    hash_table_object_handlers.clone_obj = 
        zend_objects_clone_obj;
}

PHP_MINIT_FUNCTION(hash_table)
{
    zend_class_entry ce;
    INIT_CLASS_ENTRY(ce, "HashTable", hash_table_methods);
    hash_table_class_entry = zend_register_internal_class(&ce);
    hash_table_class_entry->create_object =
        hash_table_object_new;
    hash_table_object_init(
        hash_table_class_entry
    );
    return SUCCESS;
}

使用上述擴展，可以大幅提升PHP陣列的效能，尤其適用於大規模資料的處理。

2. 堆

堆是常用的資料結構，可以用於優先佇列、排序等操作。為了提高PHP的效能，我們可以使用C語言擴充來實作堆資料結構。

下面是一個簡單的PHP擴充範例，該擴充實作了一個最小堆，可以用於排序、搜尋等操作。

typedef struct {
    zend_ulong size;
    zend_ulong capacity;
    zval *data;
} min_heap;

static min_heap *min_heap_new()
{
    min_heap *heap = emalloc(sizeof(min_heap));
    heap->size = 0;
    heap->capacity = 4;
    heap->data = emalloc(sizeof(zval) * heap->capacity);
    return heap;
}

static void min_heap_free(min_heap *heap)
{
    zend_ulong i;
    for (i = 0; i < heap->size; i++) {
        zval_dtor(&heap->data[i]);
    }
    efree(heap->data);
    efree(heap);
}

static void min_heap_push(min_heap *heap, zval *value)
{
    if (heap->size + 1 > heap->capacity) {
        heap->capacity *= 2;
        heap->data = 
            erealloc(heap->data, sizeof(zval) * heap->capacity);
    }
    zend_ulong hole = ++heap->size;
    while (hole > 1 && 
           zend_is_smaller(
               value, &heap->data[hole / 2]
           )) {
        ZVAL_COPY(
            &heap->data[hole], &heap->data[hole / 2]
        );
        hole /= 2;
    }
    ZVAL_COPY(
        &heap->data[hole], value
    );
}

static void min_heap_pop(min_heap *heap)
{
    zend_ulong hole = 1;
    zend_ulong child = 2;
    zval tmp;
    ZVAL_NULL(&tmp);
    zval_dtor(
        &heap->data[1]
    );
    heap->data[1] = heap->data[heap->size--];
    while (child <= heap->size) {
        if (child < heap->size && 
            zend_is_smaller(&heap->data[child + 1], &heap->data[child])) {
            child++;
        }
        if (zend_is_smaller(&heap->data[child], &heap->data[hole])) {
            ZVAL_COPY(
                &tmp, &heap->data[hole]
            );
            ZVAL_COPY(
                &heap->data[hole], &heap->data[child]
            );
            ZVAL_COPY(
                &heap->data[child], &tmp
            );
        } else {
            break;
        }
        hole = child;
        child *= 2;
    }
}

static zval *min_heap_top(min_heap *heap)
{
    if (heap->size > 0) {
        return &heap->data[1];
    } else {
        return NULL;
    }
}

static zend_class_entry *min_heap_class_entry;

static zend_function_entry min_heap_methods[] = {
    PHP_ME(MinHeap, push, arginfo_min_heap_push, ZEND_ACC_PUBLIC)
    PHP_ME(MinHeap, pop, arginfo_min_heap_pop, ZEND_ACC_PUBLIC)
    PHP_ME(MinHeap, top, arginfo_min_heap_top, ZEND_ACC_PUBLIC)
    PHP_FE_END
};

static zend_object_handlers min_heap_object_handlers;

static void min_heap_object_init(zend_class_entry *class_type)
{
    min_heap_object_handlers = 
        *zend_get_std_object_handlers();
    min_heap_object_handlers.offset = 
        XtOffsetOf(min_heap_object, std);
    min_heap_object_handlers.free_obj = 
        min_heap_object_free;
    min_heap_object_handlers.clone_obj = 
        zend_objects_clone_obj;
}

static zend_object *min_heap_object_new(zend_class_entry *class_type)
{
    min_heap_object *intern = 
        (min_heap_object *)ecalloc(1, sizeof(min_heap_object));
    zend_object_std_init(&intern->std, class_type);
    object_properties_init(&intern->std, class_type);
    intern->std.handlers = &min_heap_object_handlers;
    intern->heap = 
        min_heap_new();
    return &intern->std;
}

static void min_heap_object_free(zend_object *object)
{
    min_heap_object *intern = 
        min_heap_object_from_obj(object);
    if (intern->heap != NULL) {
        min_heap_free(intern->heap);
    }
    zend_object_std_dtor(object);
}

PHP_MINIT_FUNCTION(min_heap)
{
    zend_class_entry ce;
    INIT_CLASS_ENTRY(ce, "MinHeap", min_heap_methods);
    min_heap_class_entry = zend_register_internal_class(&ce);
    min_heap_class_entry->create_object =
        min_heap_object_new;
    min_heap_object_init(
        min_heap_class_entry
    );
    return SUCCESS;
}

使用上述擴展，可以輕鬆實現PHP中的堆資料結構，並提高PHP的排序、搜尋等操作的效能。

3. 佇列

PHP中的佇列是一種常見的資料結構，可以用於多執行緒任務的管理等應用場景。為了提高PHP的效能，我們可以使用C語言擴充來實作佇列資料結構。

下面是一個簡單的PHP擴充範例，該擴充實作了一個高效能的佇列，可以用於多執行緒任務的處理等應用場景。

typedef struct {
    zend_ulong head;
    zend_ulong tail;
    zend_ulong size;
    zend_ulong capacity;
    zval *data;
} queue;

static queue *queue_new()
{
    queue *q = emalloc(sizeof(queue));
    q->head = 0;
    q->tail = 0;
    q->size = 0;
    q->capacity = 4;
    q->data = emalloc(sizeof(zval) * q->capacity);
    return q;
}

static void queue_free(queue *q)
{
    zend_ulong i;
    for (i = q->head; i != q->tail; i = (i + 1) % q->capacity) {
        zval_dtor(&q->data[i]);
    }
    efree(q->data);
    efree(q);
}

static void queue_push(queue *q, zval *val)
{
    if (q->size >= q->capacity) {
        zend_ulong new_capacity = q->capacity * 2;
        zval *new_data = emalloc(sizeof(zval) * new_capacity);
        zend_ulong i;
        for (i = q->head; i != q->tail; i = (i + 1) % q->capacity) {
            ZVAL_COPY(&new_data[i], &q->data[i]);
        }
        efree(q->data);
        q->data = new_data;
        q->capacity = new_capacity;
        q->head = 0;
        q->tail = q->size;
    }
    ZVAL_COPY(&q->data[q->tail], val);
    q->tail = (q->tail + 1) % q->capacity;
    q->size++;
}

static void queue_pop(queue *q)
{
    if (q->size > 0) {
        zval_dtor(&q->data[q->head]);
        q->head = (q->head + 1) % q->capacity;
        q->size--;
    }
}

static zval *queue_front(queue *q)
{
    if (q->size > 0) {
        return &q->data[q->head];
    } else {
        return NULL;
    }
}

static zend_class_entry *queue_class_entry;

static zend_function_entry queue_methods[] = {
    PHP_ME(Queue, push, arginfo_queue_push, ZEND_ACC_PUBLIC)
    PHP_ME(Queue, pop, arginfo_queue_pop, ZEND_ACC_PUBLIC)
    PHP_ME(Queue, front, arginfo_queue_front, ZEND_ACC_PUBLIC)
    PHP_FE_END
};

static zend_object_handlers queue_object_handlers;

static void queue_object_init(zend_class_entry *class_type)
{
    queue_object_handlers = 
        *zend_get_std_object_handlers();
    queue_object_handlers.offset = 
        XtOffsetOf(queue_object, std);
    queue_object_handlers.free_obj = 
        queue_object_free;
    queue_object_handlers.clone_obj = 
        zend_objects_clone_obj;
}

static zend_object *queue_object_new(zend_class_entry *class_type)
{
    queue_object *intern = 
        (queue_object *)ecalloc(1, sizeof(queue_object));
    zend_object_std_init(&intern->std, class_type);
    object_properties_init(&intern->std, class_type);
    intern->std.handlers = &queue_object_handlers;
    intern->q = 
        queue_new();
    return &intern->std;
}

static void queue_object_free(zend_object *object)
{
    queue_object *intern = 
        queue_object_from_obj(object);
    if (intern->q != NULL) {
        queue_free(intern->q);
    }
    zend_object_std_dtor(object);
}

PHP_MINIT_FUNCTION(queue)
{
    zend_class_entry ce;
    INIT_CLASS_ENTRY(ce, "Queue", queue_methods);
    queue_class_entry = zend_register_internal_class(&ce);
    queue_class_entry->create_object =
        queue_object_new;
    queue_object_init(
        queue_class_entry
    );
    return SUCCESS;
}

使用上述擴展，可以輕鬆實現PHP中的佇列資料結構，並提高PHP多執行緒任務的處理等應用場景的效能。

總結

經過上述的介紹，我們了解了PHP底層的高效能資料結構及其實作方法，並提供了對應的程式碼範例。透過使用擴展實現高效能資料結構，可以大幅提高PHP的效能，特別是在處理大量資料和多執行緒任務的情況下，更是可以顯著地提升系統的效能。

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