High-performance data structures and implementation methods underlying PHP

PHP’s underlying high-performance data structure and implementation methods require specific code examples

With the continuous development of Internet applications, PHP has become a widely used Server-side scripting language. However, in large-scale web applications, PHP's performance issues have become a problem that cannot be ignored. Many large websites have experienced performance bottlenecks and system crashes.

In order to improve the performance of PHP, we need to understand the underlying high-performance data structure and implementation methods of PHP. This article will introduce several high-performance data structures of PHP and their implementation methods, and provide corresponding code examples to help readers deeply understand PHP performance optimization.

1. Array

In PHP, array is one of the most commonly used data structures. However, PHP's array implementation uses a hash table, which will bring some performance overhead, especially when iterating a large amount of data.

In order to improve PHP's array performance, we can use C language extensions to achieve it.

The following is a simple PHP extension example, which implements a high-performance hash table that can be used to store large amounts of data and supports the storage and access of various data types.

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;
}

Using the above extensions can greatly improve the performance of PHP arrays, especially suitable for processing large-scale data.

2. Heap

Heap is a commonly used data structure that can be used for priority queue, sorting and other operations. In order to improve the performance of PHP, we can use C language extensions to implement heap data structures.

The following is a simple PHP extension example, which implements a minimum heap and can be used for operations such as sorting and searching.

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;
}

Using the above extensions, you can easily implement the heap data structure in PHP and improve the performance of PHP sorting, search and other operations.

3. Queue

The queue in PHP is a common data structure that can be used in application scenarios such as the management of multi-threaded tasks. In order to improve the performance of PHP, we can use C language extensions to implement queue data structures.

The following is a simple PHP extension example, which implements a high-performance queue and can be used in application scenarios such as multi-threaded task processing.

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;
}

Using the above extensions, you can easily implement the queue data structure in PHP and improve the performance of PHP multi-threaded task processing and other application scenarios.

Summary

After the above introduction, we have learned about the high-performance data structure and its implementation method underlying PHP, and provided corresponding code examples. By using extensions to implement high-performance data structures, the performance of PHP can be greatly improved, especially when processing large amounts of data and multi-threaded tasks. It can significantly improve the performance of the system.

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