tango-maat/src/maat_hierarchy.cpp

/*
**********************************************************************************************
*	File: maat_hierarchy.cpp
*   Description: 
*	Authors: Zheng Chao <zhengchao@geedgenetworks.com>
*	Date:    2022-10-31
*   Copyright: (c) 2018-2022 Geedge Networks, Inc. All rights reserved.
***********************************************************************************************
*/

#include <assert.h>
#include <pthread.h>

#include "utils.h"
#include "maat_utils.h"
#include "log/log.h"
#include "uthash/utarray.h"
#include "uthash/uthash.h"
#include "bool_matcher.h"
#include "igraph/igraph.h"
#include "maat_hierarchy.h"
#include "maat_garbage_collection.h"

#define MODULE_HIERARCHY	 module_name_str("maat.hierarchy")

struct maat_hierarchy_clause_state {
	unsigned long long clause_id;
	char not_flag;
	char in_use;
	UT_array *literal_ids;
};

struct maat_hierarchy_compile {
	unsigned int magic;
	int compile_id;
	int actual_clause_num;
	int declared_clause_num;
	int not_clause_cnt;
	void *user_data;
	UT_hash_handle hh;
	struct maat_hierarchy_clause_state clause_states[MAX_ITEMS_PER_BOOL_EXPR];
};

struct maat_hierarchy_group {
	igraph_integer_t vertex_id;
	int group_id;
	int ref_by_compile_cnt;
	int ref_by_superior_group_cnt;
	int ref_by_subordinate_group_cnt;
	int ref_by_region_cnt;

	size_t top_group_cnt;
	int *top_group_ids;
	UT_hash_handle hh_group_id;
	UT_hash_handle hh_vertex_id;
};

struct maat_hierarchy_region {
	int region_id;
	int group_id;
	int table_id;

	struct maat_hierarchy_group *ref_parent_group;
	UT_hash_handle hh;

	void *user_data;
};

struct maat_hierarchy_literal_id {
	int group_id;
	int vt_id;
};

struct maat_hierarchy_clause {
	long long clause_id;
	size_t n_literal_id;
	struct maat_hierarchy_literal_id *literal_ids;
	UT_hash_handle hh;
};

struct region2clause_key {
	int region_id;
	int vt_id;
};

struct group2region {
	int group_id;
	UT_array *region_ids;
	UT_hash_handle hh;	//index to 
};

struct region2clause_value {	
	struct region2clause_key key;
	UT_array *clause_ids;
	int group_id;
	UT_hash_handle hh;	//index to 
};

struct maat_hierarchy_internal_hit_path {
	int Nth_scan;
	int Nth_hit_region;
	int region_id;
	int virtual_table_id;
};

struct maat_hierarchy
{
	pthread_rwlock_t rwlock;
	pthread_mutex_t mutex;
	time_t version;				//After full update, clause id may indicate a different clause. Comparing hier->version and mid->hier_ver can prevent false positive match.
	int changed_flag;
	
	struct maat_hierarchy_compile *hash_compile_by_id;		//key: compile_id, value: struct Maat_hierarchy_compile*.
	void (* compile_user_data_free)(void *compile_ud);

	struct maat_hierarchy_group *hash_group_by_id;			//key: group_id, value: struct Maat_hierarchy_group*.
	struct maat_hierarchy_group *hash_group_by_vertex;		//key:vetex_id, value: struct Maat_hierarchy_group*. Multimap (Items with multiple keys).

	struct maat_hierarchy_region *hash_region_by_id;		//key: region_id, value: struct Maat_hierarchy_region*.

	struct maat_hierarchy_clause *hash_dedup_clause_by_literals;		//key: literal combination, value: struct Maat_hierarchy_clause*. For generating unique clause_id.
	unsigned long long clause_id_generator;					//Increasing number.
	
	void (* region_user_data_free)(void *region_ud);	


	igraph_t group_graph;
	igraph_integer_t group_graph_vcount;
	igraph_vector_t dfs_vids;

	igraph_integer_t grp_vertex_id_generator;

	/*Following members are accessed from scan threads.*/
	struct region2clause_value *hash_region2clause;			//key: region_id+virtual_table_id, value: struct region2clause_value.
	struct bool_matcher *bm;


	int thread_num;
	struct maat_garbage_bin *ref_garbage_bin;
	struct log_handle *logger;
	struct bool_expr_match *expr_match_buff;
};

struct maat_hierarchy_compile_mid
{
	int thread_id;
	int Nth_scan;
	time_t hier_ver;
	size_t this_scan_region_hit_cnt;
	int	not_clause_hitted_flag;
	int is_no_count_scan;
	size_t hit_path_cnt;

	UT_array *internal_hit_paths;
	UT_array *all_hit_clause_array;
	UT_array *this_scan_hit_clause_ids;
};

struct maat_hierarchy *maat_hierarchy_new(int thread_num, struct maat_garbage_bin *bin, struct log_handle *logger)
{
    struct maat_hierarchy *hier = ALLOC(struct maat_hierarchy, 1);
	UNUSED int ret = 0;
	hier->logger = logger;
	hier->thread_num = thread_num;
	hier->version = time(NULL);

	hier->hash_group_by_id = NULL;
	hier->hash_group_by_vertex = NULL;
	hier->hash_compile_by_id = NULL;
	hier->hash_region2clause = NULL;
	hier->hash_region_by_id = NULL;
	hier->hash_dedup_clause_by_literals = NULL;
	hier->clause_id_generator = 0;
	hier->ref_garbage_bin = bin;	
	hier->expr_match_buff = ALLOC(struct bool_expr_match, thread_num * MAX_SCANNER_HIT_NUM);

	pthread_mutex_init(&hier->mutex, NULL);
	ret = pthread_rwlock_init(&hier->rwlock, NULL);
	assert(ret == 0);
	ret = igraph_empty(&hier->group_graph, 0, IGRAPH_DIRECTED);
	assert(ret == IGRAPH_SUCCESS);

	return hier;
}

UT_icd ut_literal_id_icd = {sizeof(struct maat_hierarchy_literal_id), NULL, NULL, NULL};
UT_icd ut_clause_id_icd = {sizeof(unsigned long long), NULL, NULL, NULL};
UT_icd ut_region_id_icd = {sizeof(int), NULL, NULL, NULL};
UT_icd ut_hit_path_icd = {sizeof(struct maat_hierarchy_internal_hit_path), NULL, NULL, NULL};

#define MAAT_HIER_COMPILE_MAGIC	0x4a5b6c7d
static struct maat_hierarchy_compile *maat_hierarchy_compile_new(struct maat_hierarchy *hier, int compile_id)
{
	struct maat_hierarchy_compile *compile = NULL;
	compile = ALLOC(struct maat_hierarchy_compile, 1);
	compile->magic = MAAT_HIER_COMPILE_MAGIC;
	compile->compile_id = compile_id;
	HASH_ADD_INT(hier->hash_compile_by_id, compile_id, compile);
	
    for(int i = 0; i < MAX_ITEMS_PER_BOOL_EXPR; i++) {	
		utarray_new(compile->clause_states[i].literal_ids, &ut_literal_id_icd);
		compile->clause_states[i].in_use=0;
	}	
	return compile;
}

static void maat_hierarchy_compile_free(struct maat_hierarchy_compile *compile)
{
	struct maat_hierarchy_clause_state *clause_state = NULL;
	//user_data must be freed before calling this function.
	assert(compile->user_data == NULL);

	for (int i = 0; i < MAX_ITEMS_PER_BOOL_EXPR; i++) {
		clause_state = compile->clause_states + i;
		utarray_free(clause_state->literal_ids);
		clause_state->literal_ids = NULL;
		clause_state->in_use = 0;
	}
	compile->magic = 0;
	free(compile);
}

void maat_hierarchy_free_region2clause_hash(struct region2clause_value* hash)
{
	struct region2clause_value *r2c_val = NULL, *tmp_r2c_val = NULL;
	HASH_ITER(hh, hash, r2c_val, tmp_r2c_val) {
		HASH_DEL(hash, r2c_val);
		utarray_free(r2c_val->clause_ids);
		free(r2c_val);
	}
	assert(hash == NULL);
}

static struct maat_hierarchy_region *
maat_hierarchy_region_new(struct maat_hierarchy *hier, int region_id, int group_id, int table_id, 
                          struct maat_hierarchy_group *parent_group, void *user_data)
{
	struct maat_hierarchy_region *region = NULL;
	region = ALLOC(struct maat_hierarchy_region, 1);
	region->group_id = group_id;
	region->region_id = region_id;
	region->table_id = table_id;
	region->ref_parent_group = parent_group;
	region->user_data = user_data;
	HASH_ADD_INT(hier->hash_region_by_id, region_id, region);
	parent_group->ref_by_region_cnt++;

	return region;
}

static void maat_hierarchy_region_free(struct maat_hierarchy *hier, struct maat_hierarchy_region *region)
{
	HASH_DELETE(hh, hier->hash_region_by_id, region);
	region->ref_parent_group->ref_by_region_cnt--;

	if (hier->region_user_data_free && region->user_data) {
		hier->region_user_data_free(region->user_data);
		region->user_data = NULL;
	}
	free(region);
}

static const struct maat_hierarchy_clause *
maat_hierarchy_clause_fetch(struct maat_hierarchy *hier, struct maat_hierarchy_literal_id *literal_ids, 
                            size_t n_literal_id)
{
	struct maat_hierarchy_clause *clause = NULL;

	HASH_FIND(hh, hier->hash_dedup_clause_by_literals, literal_ids, 
			  n_literal_id * sizeof(struct maat_hierarchy_literal_id), clause);
	if (!clause) {
		clause = ALLOC(struct maat_hierarchy_clause, 1);
		clause->clause_id = hier->clause_id_generator;
		clause->n_literal_id = n_literal_id;
		clause->literal_ids = ALLOC(struct maat_hierarchy_literal_id, n_literal_id);
		memcpy(clause->literal_ids, literal_ids, n_literal_id * sizeof(struct maat_hierarchy_literal_id));
		
		hier->clause_id_generator++;
		HASH_ADD_KEYPTR(hh, hier->hash_dedup_clause_by_literals, clause->literal_ids, 
			            n_literal_id * sizeof(struct maat_hierarchy_literal_id), clause);
	}

	return clause;
}

static void maat_hierarchy_clause_free(struct maat_hierarchy *hier, struct maat_hierarchy_clause *clause)
{
	HASH_DELETE(hh, hier->hash_dedup_clause_by_literals, clause);
	free(clause->literal_ids);
	clause->n_literal_id = 0;
	free(clause);
}

static void group_vertex_free(struct maat_hierarchy_group *group)
{
	free(group->top_group_ids);
	free(group);
}

void maat_hierarchy_free(struct maat_hierarchy *hier)
{
    struct maat_hierarchy_compile *compile = NULL, *tmp_compile = NULL;
	struct maat_hierarchy_group *group = NULL, *tmp_group = NULL;
	struct region2clause_value *r2c_val = NULL, *tmp_r2c_val = NULL;
	struct maat_hierarchy_region *region = NULL, *tmp_region = NULL;
	struct maat_hierarchy_clause *clause = NULL, *tmp_clause = NULL;
	pthread_rwlock_wrlock(&hier->rwlock);

	//Reference: https://troydhanson.github.io/uthash/userguide.html#_what_can_it_do
	//Some have asked how uthash cleans up its internal memory. 
	//The answer is simple: when you delete the final item from a hash table, 
	//uthash releases all the internal memory associated with that hash table, 
	//and sets its pointer to NULL.
	HASH_ITER(hh, hier->hash_compile_by_id, compile, tmp_compile) {
		if (hier->compile_user_data_free && compile->user_data) {
			hier->compile_user_data_free(compile->user_data);
			compile->user_data = NULL;
		}		
		HASH_DEL(hier->hash_compile_by_id, compile);
		maat_hierarchy_compile_free(compile);
	}
	assert(hier->hash_compile_by_id == NULL);
	
	HASH_ITER(hh, hier->hash_region2clause, r2c_val, tmp_r2c_val) {
		HASH_DEL(hier->hash_region2clause, r2c_val);
		utarray_free(r2c_val->clause_ids);
		free(r2c_val);
	}

	maat_hierarchy_free_region2clause_hash(hier->hash_region2clause);

	HASH_ITER(hh, hier->hash_region_by_id, region, tmp_region) {
		maat_hierarchy_region_free(hier, region);
	}

	HASH_ITER(hh, hier->hash_dedup_clause_by_literals, clause, tmp_clause) {
		maat_hierarchy_clause_free(hier, clause);
	}

	//Free group as the last.
	HASH_CLEAR(hh_vertex_id, hier->hash_group_by_vertex);//No need group memory clean up.
	HASH_ITER(hh_group_id, hier->hash_group_by_id, group, tmp_group) {
		HASH_DELETE(hh_group_id, hier->hash_group_by_id, group);
		group_vertex_free(group);
	}
	assert(hier->hash_group_by_id == NULL);	
	
	igraph_destroy(&hier->group_graph);
	bool_matcher_free(hier->bm);
	hier->bm = NULL;

	pthread_rwlock_unlock(&hier->rwlock);
	pthread_rwlock_destroy(&hier->rwlock);

	FREE(hier->expr_match_buff);
	FREE(hier);
}

size_t print_igraph_vector(igraph_vector_t *v, char *buff, size_t sz) 
{
  int printed = 0;

  for (long int i = 0; i < igraph_vector_size(v); i++) {
    printed += snprintf(buff + printed, sz - printed, " %li", (long int)VECTOR(*v)[i]);
  }

  return printed;
}

struct maat_hierarchy_group *maat_hierarchy_group_new(struct maat_hierarchy *hier, int group_id)
{
	struct maat_hierarchy_group *group = NULL;

	group = ALLOC(struct maat_hierarchy_group, 1);
	group->group_id = group_id;
	group->vertex_id = hier->grp_vertex_id_generator++;
	assert(igraph_vcount(&hier->group_graph) == group->vertex_id);
	igraph_add_vertices(&hier->group_graph, 1, NULL);	//Add 1 vertice.
	
	HASH_ADD(hh_group_id, hier->hash_group_by_id, group_id, sizeof(group->group_id), group);
	HASH_ADD(hh_vertex_id, hier->hash_group_by_vertex, vertex_id, sizeof(group->vertex_id), group);

	return group;
}

static void maat_hierarchy_group_free(struct maat_hierarchy *hier, struct maat_hierarchy_group *group)
{
	igraph_vector_t v; 
	char buff[4096] = {0};

	assert(group->ref_by_compile_cnt == 0 && group->ref_by_superior_group_cnt == 0);
	igraph_vector_init(&v, 8);
	igraph_neighbors(&hier->group_graph, &v, group->vertex_id, IGRAPH_ALL);

	if (igraph_vector_size(&v) > 0) {
		print_igraph_vector(&v, buff, sizeof(buff));
		log_error(hier->logger, MODULE_HIERARCHY, "Del group %d exception, still reached by %s.",
						                          group->vertex_id, buff);
		assert(0);
	}
	igraph_vector_destroy(&v);
	assert(group->top_group_ids==NULL);
	//We should not call igraph_delete_vertices, because this is function changes the ids of the vertices.
	//igraph_delete_vertices(&hier->group_graph, igraph_vss_1(group->vertex_id));

	HASH_DELETE(hh_group_id, hier->hash_group_by_id, group);
	HASH_DELETE(hh_vertex_id, hier->hash_group_by_vertex, group);

	group_vertex_free(group);
}

static size_t effective_vertices_count(igraph_vector_t *vids)
{
    size_t i = 0;
	int tmp_vid = 0;
	for (i = 0; i < (size_t)igraph_vector_size(vids); i++) {
		tmp_vid = (int) VECTOR(*vids)[i];
		if (tmp_vid < 0) {
			break;
		}
	}

	return i;
}

static int maat_hierarchy_build_top_groups(struct maat_hierarchy *hier)
{
	struct maat_hierarchy_group *group = NULL, *tmp = NULL;
	struct maat_hierarchy_group *superior_group = NULL;
	int tmp_vid=0;
	size_t i=0, top_group_cnt=0;
	int* temp_group_ids=NULL;
	
	igraph_bool_t is_dag;
	igraph_is_dag(&(hier->group_graph), &is_dag);
	if (!is_dag) {
		log_error(hier->logger, MODULE_HIERARCHY, "Sub group cycle detected!");
		return -1;
	}

	hier->group_graph_vcount = igraph_vcount(&hier->group_graph);
	igraph_vector_init(&(hier->dfs_vids), hier->group_graph_vcount);
	
	HASH_ITER (hh_group_id, hier->hash_group_by_id, group, tmp) {
		top_group_cnt = 0;
		temp_group_ids = NULL;
		//Orphan, Not reference by any one, free it.
		if (0 == group->ref_by_compile_cnt
			&& 0 == group->ref_by_superior_group_cnt
			&& 0 == group->ref_by_subordinate_group_cnt
			&& 0 == group->ref_by_region_cnt) {
		
			FREE(group->top_group_ids);
			maat_hierarchy_group_free(hier, group);
			continue;
		}

		//A group is need to build top groups when it has regions and referenced by superior groups or compiles.
		if (group->ref_by_region_cnt > 0 && 
            (group->ref_by_compile_cnt > 0 || group->ref_by_superior_group_cnt > 0)) {
			if (0 == group->ref_by_superior_group_cnt) {
				//fast path, group is only referenced by compile rules.
				top_group_cnt = 1;
				temp_group_ids = ALLOC(int, top_group_cnt);
				temp_group_ids[0] = group->group_id;
			} else {
				igraph_vector_t *vids = &(hier->dfs_vids);
				igraph_dfs(&hier->group_graph, group->vertex_id, IGRAPH_OUT, 
							0, vids, NULL, NULL, NULL, NULL, NULL, NULL);
				
				temp_group_ids = ALLOC(int, effective_vertices_count(vids));
				
				for (size_t i = 0; i < (size_t)igraph_vector_size(vids); i++) {
					tmp_vid = (int) VECTOR(*vids)[i];
					if (tmp_vid < 0) {
						break;
					}

					HASH_FIND(hh_vertex_id, hier->hash_group_by_vertex, &tmp_vid, sizeof(tmp_vid), superior_group);

                    //including itself
					if (superior_group->ref_by_compile_cnt > 0) {
						temp_group_ids[top_group_cnt] = superior_group->group_id;
						top_group_cnt++;
					}
				}
			}
		}

		free(group->top_group_ids);
		group->top_group_cnt = top_group_cnt;
		group->top_group_ids = ALLOC(int, group->top_group_cnt);
		memcpy(group->top_group_ids, temp_group_ids, sizeof(int)*group->top_group_cnt);

		FREE(temp_group_ids);
	}	
	igraph_vector_destroy(&hier->dfs_vids);

	return 0;
}

static struct bool_matcher *maat_hierarchy_build_bool_matcher(struct maat_hierarchy *hier)
{
	struct bool_matcher *bm = NULL;
	size_t compile_num = 0, expr_cnt = 0;
	struct bool_expr *bool_expr_array = NULL;
	struct maat_hierarchy_compile *compile = NULL, *tmp_compile = NULL;
	
	struct maat_hierarchy_clause_state *clause_state = NULL;
	const struct maat_hierarchy_clause *clause = NULL;
	size_t i = 0, j = 0;
	int has_clause_num = 0;
	compile_num = HASH_COUNT(hier->hash_compile_by_id);	
	
	if (0 == compile_num) {
		log_error(hier->logger, MODULE_HIERARCHY, "No compile to build.");
		return NULL;
	}

	//STEP 1, update clause_id of each compile and literal
	struct maat_hierarchy_literal_id *literal_ids = NULL;
	size_t n_literal_id = 0;
	HASH_ITER(hh, hier->hash_compile_by_id, compile, tmp_compile) {
		has_clause_num = 0;
		for (i = 0; i < MAX_ITEMS_PER_BOOL_EXPR; i++) {
			clause_state = compile->clause_states + i;
			clause_state->clause_id = 0;
			if (!clause_state->in_use) {
				continue;
			}

			has_clause_num++;
			literal_ids = (struct maat_hierarchy_literal_id *)utarray_eltptr(clause_state->literal_ids, 0);
			n_literal_id = utarray_len(clause_state->literal_ids);
			clause = maat_hierarchy_clause_fetch(hier, literal_ids, n_literal_id);
			clause_state->clause_id = clause->clause_id;
		}
		assert(has_clause_num == compile->actual_clause_num);
	}
	
	//STEP 2, serial compile clause states to a bool expression array.
	compile_num = HASH_COUNT(hier->hash_compile_by_id);
	bool_expr_array = ALLOC(struct bool_expr, compile_num);
	HASH_ITER(hh, hier->hash_compile_by_id, compile, tmp_compile) {
		for (i = 0, j = 0; i < MAX_ITEMS_PER_BOOL_EXPR; i++) {
			if (compile->clause_states[i].in_use) {
				if (compile->clause_states[i].not_flag) {
					compile->not_clause_cnt++;
				}
				bool_expr_array[expr_cnt].items[j].item_id = compile->clause_states[i].clause_id;
				bool_expr_array[expr_cnt].items[j].not_flag = compile->clause_states[i].not_flag;
				j++;
			}
		}
		//some compile may have zero groups, e.g. default policy.
		if (j == (size_t)compile->declared_clause_num && j > 0) {
			bool_expr_array[expr_cnt].expr_id = compile->compile_id;
			bool_expr_array[expr_cnt].user_tag = compile;
			bool_expr_array[expr_cnt].item_num = j;
			expr_cnt++;
		}
	}

	//STEP 3, build the bool matcher.
	size_t mem_size = 0;
	if (0 == expr_cnt) {		
		log_error(hier->logger, MODULE_HIERARCHY, "No bool expression to build.");
		goto error_out;
	}

	bm = bool_matcher_new(bool_expr_array, expr_cnt, &mem_size);
	if (bm != NULL) {
		log_info(hier->logger, MODULE_HIERARCHY,
				"Build bool matcher of %zu expressions with %zu bytes memory.", expr_cnt, mem_size);
	} else {
		log_error(hier->logger, MODULE_HIERARCHY, "Build bool matcher failed!");
	}

error_out:
	FREE(bool_expr_array);

	return bm;
}

static inline int compare_clause_id(const void *a, const void *b)
{
	long long ret = *(const unsigned long long *)a - *(const unsigned long long *)b;

	if (0 == ret) {
		return 0;
	} else if(ret < 0) {
		return -1;
	} else {
		return 1;
	}
}

static inline int compare_region_id(const void *a, const void *b)
{
	return (*(int*)a - *(int*)b);
}

struct region2clause_value *maat_hierarchy_build_region2clause_hash(struct maat_hierarchy *hier)
{
	size_t i = 0, j = 0, k = 0;
	struct maat_hierarchy_compile *compile = NULL, *tmp_compile = NULL;
	struct maat_hierarchy_literal_id *literal_id = NULL;
	struct maat_hierarchy_clause_state *clause_state = NULL;

	struct maat_hierarchy_region *region = NULL, *tmp_region = NULL;
	struct maat_hierarchy_group *group = NULL;
	struct group2region *g2r_hash = NULL, *g2r = NULL, *g2r_tmp = NULL;
	struct region2clause_value *region2clause_hash = NULL, *r2c_val = NULL;
	struct region2clause_key r2c_key;

	//Build a temporary hash that maps group to its regions.
	HASH_ITER(hh, hier->hash_region_by_id, region, tmp_region) {
		group = region->ref_parent_group;
		for (i = 0; i < group->top_group_cnt; i++) {
			HASH_FIND_INT(g2r_hash, group->top_group_ids+i, g2r);
			if (!g2r) {
				g2r = ALLOC(struct group2region, 1);
				utarray_new(g2r->region_ids, &ut_region_id_icd);
				utarray_reserve(g2r->region_ids, group->ref_by_region_cnt);
				g2r->group_id = group->top_group_ids[i];
				HASH_ADD_INT(g2r_hash, group_id, g2r);
			}
			
			//One region belongs to one group, one group may have many regions. So duplicate region check is unnecessary.
			//if(utarray_find(g2r->region_ids, &(region->region_id), compare_region_id)) assert(0);

			utarray_push_back(g2r->region_ids, &(region->region_id));
			//utarray_sort(g2r->region_ids, compare_region_id);
		}
	}

	//Build short cut hash that maps region_id+vt_id to clause_ids.
	HASH_ITER(hh, hier->hash_compile_by_id, compile, tmp_compile) {
		for (i = 0; i < MAX_ITEMS_PER_BOOL_EXPR; i++) {
			clause_state = compile->clause_states + i;
			if (!clause_state->in_use) {
				continue;
			}

			for (j = 0; j < utarray_len(clause_state->literal_ids); j++) {
				literal_id = (struct maat_hierarchy_literal_id *)utarray_eltptr(clause_state->literal_ids, j);
				HASH_FIND(hh_group_id, hier->hash_group_by_id, &(literal_id->group_id), sizeof(literal_id->group_id), group);
				if (!group) {
					continue;
				}
				HASH_FIND_INT(g2r_hash, &(group->group_id), g2r);

                //group declared by compile, but has no subordinate or region.
				if (!g2r) {
					continue;
				}

				for (k = 0; k < utarray_len(g2r->region_ids); k++) {
					r2c_key.region_id = *((int*)utarray_eltptr(g2r->region_ids, k));
					r2c_key.vt_id = literal_id->vt_id;
					HASH_FIND(hh, region2clause_hash, &r2c_key, sizeof(r2c_key), r2c_val);
					if (!r2c_val) {
						r2c_val = ALLOC(struct region2clause_value, 1);
						r2c_val->key = r2c_key;
						r2c_val->group_id = g2r->group_id;
						utarray_new(r2c_val->clause_ids, &ut_clause_id_icd);
						HASH_ADD(hh, region2clause_hash, key, sizeof(r2c_val->key), r2c_val);
					}

					if (utarray_find(r2c_val->clause_ids, &(clause_state->clause_id), compare_clause_id)) {
						continue;
					}
					utarray_push_back(r2c_val->clause_ids, &(clause_state->clause_id));
					utarray_sort(r2c_val->clause_ids, compare_clause_id);
				}				
			}
		}
	}

	int tmp1 = 0, tmp2 = 0;
	HASH_ITER(hh, g2r_hash, g2r, g2r_tmp) {
		HASH_DEL(g2r_hash, g2r);
		//Sanity Check
		utarray_sort(g2r->region_ids, compare_region_id);
		for (i = 1; i < utarray_len(g2r->region_ids); i++) {			
			tmp1 = *((int*)utarray_eltptr(g2r->region_ids, i-1));
			tmp2 = *((int*)utarray_eltptr(g2r->region_ids, i));
			assert(tmp1!=tmp2);
		}
		utarray_free(g2r->region_ids);
		g2r->region_ids = NULL;
		free(g2r);
	}

	log_info(hier->logger, MODULE_HIERARCHY, "Build region2clause hash with %llu element.",
								             HASH_COUNT(region2clause_hash));
	return region2clause_hash;
}

int maat_hierarchy_rebuild(struct maat_hierarchy *hier)
{
    int ret=0;
	struct bool_matcher *new_bm = NULL, *old_bm = NULL;
	struct region2clause_value *new_region2clause_hash = NULL, *old_region2clause_hash = NULL;

	//Read hier from update thread is OK.
	if (!hier->changed_flag) {
		return ret;
	}

	ret = maat_hierarchy_build_top_groups(hier);
	new_bm = maat_hierarchy_build_bool_matcher(hier);
	new_region2clause_hash = maat_hierarchy_build_region2clause_hash(hier);

	pthread_rwlock_wrlock(&hier->rwlock);

	old_bm = hier->bm;		
	old_region2clause_hash = hier->hash_region2clause;

	hier->bm = new_bm;
	hier->hash_region2clause = new_region2clause_hash;
	hier->changed_flag = 0;
	pthread_rwlock_unlock(&hier->rwlock);

	maat_garbage_bagging(hier->ref_garbage_bin, old_bm, (void (*)(void*))bool_matcher_free);	
	maat_garbage_bagging(hier->ref_garbage_bin, old_region2clause_hash, 
                        (void (*)(void*))maat_hierarchy_free_region2clause_hash);

	return ret;
}

size_t maat_hierarchy_get_hit_paths(struct maat_hierarchy *hier, struct maat_hierarchy_compile_mid *mid, 
									struct maat_hit_path_t *hit_paths, size_t n_path)
{

}

void maat_hierarchy_set_compile_user_data_free_func(struct maat_hierarchy *hier,  void (* func)(void *))
{
    hier->compile_user_data_free = func;
}

void maat_hierarchy_set_region_user_data_free_func(struct maat_hierarchy *hier,  void (* func)(void *))
{
    hier->region_user_data_free = func;
}

struct maat_hierarchy_compile_mid *maat_hierarchy_compile_mid_new(struct maat_hierarchy *hier, int thread_id)
{
    struct maat_hierarchy_compile_mid *mid = ALLOC(struct maat_hierarchy_compile_mid, 1);

	mid->thread_id = thread_id;
	mid->hier_ver = hier->version;
	utarray_new(mid->internal_hit_paths, &ut_hit_path_icd);
	utarray_new(mid->all_hit_clause_array, &ut_clause_id_icd);
	utarray_new(mid->this_scan_hit_clause_ids, &ut_clause_id_icd);

	return mid;
}

void maat_hierarchy_compile_mid_free(struct maat_hierarchy_compile_mid *mid)
{
    utarray_free(mid->internal_hit_paths);
	utarray_free(mid->all_hit_clause_array);
	utarray_free(mid->this_scan_hit_clause_ids);
	free(mid);
}

static int maat_hierarchy_hit_path_add(UT_array *hit_paths, int region_id, int virtual_table_id, 
                                       int Nth_scan, int Nth_region_result)
{
	struct maat_hierarchy_internal_hit_path new_path;

	new_path.region_id = region_id;
	new_path.Nth_hit_region = Nth_region_result;
	new_path.Nth_scan = Nth_scan;
	new_path.virtual_table_id = virtual_table_id;
	
	utarray_push_back(hit_paths, &new_path);
	return 1;
}

void maat_hierarchy_compile_mid_update(struct maat_hierarchy *hier, 
                                       struct maat_hierarchy_compile_mid *mid, 
                                       int region_id, int virtual_table_id, 
                                       int Nth_scan, int Nth_region_result)
{
	if (mid->Nth_scan != Nth_scan) {
		assert(mid->this_scan_region_hit_cnt == 0);
		mid->Nth_scan = Nth_scan;
		utarray_clear(mid->this_scan_hit_clause_ids);
	}

	int ret = maat_hierarchy_hit_path_add(mid->internal_hit_paths, region_id, virtual_table_id, 
                                          Nth_scan, Nth_region_result);
	if (!ret) {
		return;
	}
	mid->hit_path_cnt++;
	mid->this_scan_region_hit_cnt++;

	struct region2clause_value* r2c_val = NULL;
	struct region2clause_key r2c_key;
	r2c_key.region_id = region_id;
	r2c_key.vt_id = virtual_table_id;

	HASH_FIND(hh, hier->hash_region2clause, &r2c_key, sizeof(r2c_key), r2c_val);
	if (!r2c_val) {
		return;
	}

    size_t i = 0;
    unsigned long long *clause_id = 0;
	size_t new_clause_idx = utarray_len(mid->this_scan_hit_clause_ids);
	for (size_t i = 0; i < utarray_len(r2c_val->clause_ids); i++) {
		clause_id = (unsigned long long *)utarray_eltptr(r2c_val->clause_ids, i);
		if (utarray_find(mid->all_hit_clause_array, clause_id, compare_clause_id)) {
			continue;
		}
		utarray_push_back(mid->this_scan_hit_clause_ids, clause_id);
	}

	if (utarray_len(mid->this_scan_hit_clause_ids) - new_clause_idx) {
		utarray_reserve(mid->all_hit_clause_array, utarray_len(mid->this_scan_hit_clause_ids) - new_clause_idx);
		for (i = new_clause_idx; i < utarray_len(mid->this_scan_hit_clause_ids); i++) {
			clause_id = (unsigned long long *)utarray_eltptr(mid->this_scan_hit_clause_ids, i);
			utarray_push_back(mid->all_hit_clause_array, clause_id);
		}
		utarray_sort(mid->all_hit_clause_array, compare_clause_id);
	}
}

int maat_hierarchy_compile_mid_has_NOT_clause(struct maat_hierarchy_compile_mid *mid)
{   
    return mid->not_clause_hitted_flag;
}

int maat_hierarchy_compile_add(struct maat_hierarchy *hier, int compile_id, 
                               int declared_clause_num, void *user_data)
{
    int ret = 0;
	struct maat_hierarchy_compile *compile = NULL;
	
	pthread_rwlock_wrlock(&hier->rwlock);
	hier->changed_flag = 1;
	HASH_FIND_INT(hier->hash_compile_by_id, &compile_id, compile);
	if (!compile) {
		assert(declared_clause_num >= 0);
		compile = maat_hierarchy_compile_new(hier, compile_id);
		compile->declared_clause_num = declared_clause_num;
		compile->user_data = user_data;
	} else {
		if (compile->user_data != NULL) {
			log_error(hier->logger, MODULE_HIERARCHY, 
                      "Add compile %d failed, compile is already exisited.", compile_id);
			ret = -1;
		} else {
			compile->declared_clause_num = declared_clause_num;
			compile->user_data = user_data;
		}
	}
	pthread_rwlock_unlock(&hier->rwlock);

	return ret;
}

int maat_hierarchy_compile_remove(struct maat_hierarchy *hier, int compile_id)
{
    int ret = 0;
    struct maat_hierarchy_compile *compile = NULL;
	
	pthread_rwlock_wrlock(&hier->rwlock);
	hier->changed_flag = 1;
	HASH_FIND_INT(hier->hash_compile_by_id, &compile_id, compile);
	if (compile) {
		if (hier->compile_user_data_free && compile->user_data) {
			hier->compile_user_data_free(compile->user_data);
			compile->user_data = NULL;
		}
        
		if (0 == compile->actual_clause_num) {		
			HASH_DEL(hier->hash_compile_by_id, compile);
			maat_garbage_bagging(hier->ref_garbage_bin, compile, (void (*)(void*))maat_hierarchy_compile_free);
		}
		ret = 0;
	} else {
		log_error(hier->logger, MODULE_HIERARCHY,
				  "Remove compile %d failed, compile is not exisited.", compile_id);
		ret = -1;
	}
	pthread_rwlock_unlock(&hier->rwlock);

	return ret;
}

static void *maat_hier_compile_get_user_data(struct maat_hierarchy* hier, int compile_id, int is_dettach)
{
	struct maat_hierarchy_compile *compile = NULL;
	void *ret = NULL;
	
	pthread_rwlock_rdlock(&hier->rwlock);
	HASH_FIND_INT(hier->hash_compile_by_id, &compile_id, compile);
	if (compile) {
		ret = compile->user_data;
		if (is_dettach) {
			compile->user_data = NULL;
		}
	}
	pthread_rwlock_unlock(&hier->rwlock);

	return ret;
}

void *maat_hierarchy_compile_dettach_user_data(struct maat_hierarchy *hier, int compile_id)
{
	return maat_hier_compile_get_user_data(hier, compile_id, 1);
}

void *maat_hierarchy_compile_read_user_data(struct maat_hierarchy *hier, int compile_id)
{
    return maat_hier_compile_get_user_data(hier, compile_id, 0);
}

void maat_hierarchy_compile_user_data_iterate(struct maat_hierarchy *hier, void (*callback)(void *user_data, void *param), void *param)
{
    struct maat_hierarchy_compile *compile = NULL, *tmp_compile = NULL;

	pthread_rwlock_rdlock(&hier->rwlock);
	HASH_ITER(hh, hier->hash_compile_by_id, compile, tmp_compile) {
		if (compile->user_data) {
			callback(compile->user_data, param);
		}
	}
	pthread_rwlock_unlock(&hier->rwlock);
}

static int maat_hierarchy_compile_has_clause(struct maat_hierarchy_compile* compile, unsigned long long clause_id)
{
	struct maat_hierarchy_clause_state *clause_state = NULL;

	for (size_t i = 0; i < MAX_ITEMS_PER_BOOL_EXPR; i++) {
		clause_state = compile->clause_states + i;
		if (!clause_state->in_use) {
			continue;
		}

		if (clause_state->clause_id == clause_id) {
			return 1;
		}
	}

	return 0;
}

static size_t maat_hierarchy_compile_mid_if_new_hit_compile(struct maat_hierarchy_compile_mid *mid, 
                                                            struct maat_hierarchy_compile *compile)
{
	size_t r_in_c_cnt = 0;

	unsigned long long new_hit_clause_id = 0;
	for(size_t i = 0; i<utarray_len(mid->this_scan_hit_clause_ids); i++) {
		new_hit_clause_id = *(unsigned long long*)utarray_eltptr(mid->this_scan_hit_clause_ids, i);
		int ret = maat_hierarchy_compile_has_clause(compile, new_hit_clause_id);
		if (ret) {
			r_in_c_cnt++;
		}
	}
	return r_in_c_cnt;
}

int maat_hierarchy_region_compile(struct maat_hierarchy *hier, struct maat_hierarchy_compile_mid *mid, 
                                  int is_last_compile, void **user_data_array, size_t ud_array_sz)
{
    int bool_match_ret = 0, i = 0;
	struct maat_hierarchy_compile *compile = NULL;
	struct bool_expr_match *expr_match = hier->expr_match_buff + (mid->thread_id * MAX_SCANNER_HIT_NUM);

	size_t r_in_c_cnt = 0;
    size_t ud_result_cnt = 0;
    size_t this_scan_region_hits = mid->this_scan_region_hit_cnt;
	
	if (!hier->bm || 0 == utarray_len(mid->all_hit_clause_array) || hier->version != mid->hier_ver) {
		mid->this_scan_region_hit_cnt = 0;
		return 0;
	}

	bool_match_ret = bool_matcher_match(hier->bm, (unsigned long long *)utarray_eltptr(mid->all_hit_clause_array, 0), 
                                        utarray_len(mid->all_hit_clause_array), expr_match, MAX_SCANNER_HIT_NUM);
	for (i = 0; i < bool_match_ret && ud_result_cnt < ud_array_sz; i++) {
		compile = (struct maat_hierarchy_compile *)expr_match[i].user_tag;
		assert(compile->magic == MAAT_HIER_COMPILE_MAGIC);
		assert((unsigned long long)compile->compile_id == expr_match[i].expr_id);
		if (0 == compile->actual_clause_num) {
			continue;
		}

		r_in_c_cnt = maat_hierarchy_compile_mid_if_new_hit_compile(mid, compile);
		if (compile->not_clause_cnt > 0 && !is_last_compile) {
			mid->not_clause_hitted_flag = 1;
		} else if(compile->user_data) {
            //For compile may be dettached by Maat_hierarchy_compile_dettach_user_data, only return non-NULL userdata.		
			if (r_in_c_cnt > 0 ||				//compile hitted becasue of new reigon
				this_scan_region_hits == 0)	//or hit a compile that refer a NOT-logic group in previous scan.
			{
				user_data_array[ud_result_cnt]=compile->user_data;
				ud_result_cnt++;
			}
		}
	}

	mid->this_scan_region_hit_cnt = 0;

	return ud_result_cnt;
}

void *maat_hierarchy_region_dettach_user_data(struct maat_hierarchy *hier, int region_id)
{
    struct maat_hierarchy_region *region = NULL;
	void *ret = NULL;

	pthread_rwlock_wrlock(&hier->rwlock);
	hier->changed_flag = 1;
	HASH_FIND_INT(hier->hash_region_by_id, &region_id, region);
	if (region) {
		ret = region->user_data;
		region->user_data = NULL;
	}
	pthread_rwlock_unlock(&hier->rwlock);

	return ret;
}

int compare_literal_id(const void *pa, const void *pb)
{
	struct maat_hierarchy_literal_id *la = (struct maat_hierarchy_literal_id *)pa;
	struct maat_hierarchy_literal_id *lb = (struct maat_hierarchy_literal_id *)pb;

	int ret = la->vt_id - lb->vt_id;
	if (ret == 0) {
		ret = la->group_id - lb->group_id;
	}

	return ret;
}

static int maat_hierarchy_compile_add_literal(struct maat_hierarchy_compile *compile, 
                                              struct maat_hierarchy_literal_id *literal_id, 
                                              int not_flag, int clause_index)
{
    struct maat_hierarchy_literal_id *tmp = NULL;
	struct maat_hierarchy_clause_state *clause_state = compile->clause_states + clause_index;
	clause_state->not_flag = not_flag;

	if (!clause_state->in_use) {
		clause_state->in_use = 1;
		compile->actual_clause_num++;
	}

    tmp = (struct maat_hierarchy_literal_id *)utarray_find(clause_state->literal_ids, literal_id, compare_literal_id);
	if (tmp) {
		assert(*(unsigned long long*)tmp == *(unsigned long long*)(literal_id));
		return -1;
	} else {
		utarray_push_back(clause_state->literal_ids, literal_id);
		utarray_sort(clause_state->literal_ids, compare_literal_id);
	}

	return 0;
}

static int maat_hierarchy_compile_remove_literal(struct maat_hierarchy_compile *compile, 
                                                 struct maat_hierarchy_literal_id *literal_id, 
                                                 int clause_index)
{
    struct maat_hierarchy_literal_id *tmp = NULL;
	struct maat_hierarchy_clause_state *clause_state = compile->clause_states + clause_index;

	tmp = (struct maat_hierarchy_literal_id *)utarray_find(clause_state->literal_ids, literal_id , compare_literal_id);
	if (tmp) {
		assert(*(unsigned long long*)tmp == *(unsigned long long*)(literal_id));
	} else {
		return -1;
	}

	size_t remove_idx = utarray_eltidx(clause_state->literal_ids, tmp);
	utarray_erase(clause_state->literal_ids, remove_idx, 1);
	if (0 == utarray_len(clause_state->literal_ids)) {
		clause_state->in_use = 0;
		compile->actual_clause_num--;
	}

	return 0;
}

int maat_hierarchy_add_group_to_compile(struct maat_hierarchy *hier, int group_id, int vt_id, 
                                        int not_flag, int clause_index, int compile_id)
{
    int ret = 0;
	struct maat_hierarchy_group *group = NULL;
	struct maat_hierarchy_literal_id literal_id = {group_id, vt_id};
	struct maat_hierarchy_compile *compile = NULL;
	
	pthread_rwlock_wrlock(&hier->rwlock);
	hier->changed_flag = 1;
	HASH_FIND(hh_group_id, hier->hash_group_by_id, &group_id, sizeof(group_id), group);
	if (!group) {
		group = maat_hierarchy_group_new(hier, group_id);
	}

	HASH_FIND(hh, hier->hash_compile_by_id, &compile_id, sizeof(compile_id), compile);
	if (!compile) {
		compile = maat_hierarchy_compile_new(hier, compile_id);
	}
	
	ret = maat_hierarchy_compile_add_literal(compile, &literal_id, not_flag, clause_index);	
	if (ret < 0) {
		log_error(hier->logger, MODULE_HIERARCHY,
				  "Add group %d vt_id %d to clause %d of compile %d failed, group is already exisited.",
				  group_id, vt_id, clause_index, compile_id);
		ret = -1;
	} else {
		ret = 0;
		group->ref_by_compile_cnt++;
	}	
	pthread_rwlock_unlock(&hier->rwlock);

	return ret;
}

int maat_hierarchy_remove_group_from_compile(struct maat_hierarchy *hier, int group_id, int vt_id, 
                                             int not_flag, int clause_index, int compile_id)
{
    struct maat_hierarchy_group *group = NULL;
	struct maat_hierarchy_literal_id literal_id = {group_id, vt_id};	
	struct maat_hierarchy_compile *compile = NULL;
	int ret = 0;
	
	pthread_rwlock_wrlock(&hier->rwlock);
	hier->changed_flag = 1;
	HASH_FIND(hh_group_id, hier->hash_group_by_id, &group_id, sizeof(group_id), group);
	if (!group) {
		log_error(hier->logger, MODULE_HIERARCHY,
				  "Remove group %d from compile %d failed, group is not exisited.",
				  group_id, compile_id);
		goto error_out;
	}

	HASH_FIND(hh, hier->hash_compile_by_id, &compile_id, sizeof(compile_id), compile);
	if (!compile) {
		log_error(hier->logger, MODULE_HIERARCHY,
				  "Remove group %d from compile %d failed, compile is not exisited.",
				  group_id, compile_id);
		goto error_out;		
	}

	ret = maat_hierarchy_compile_remove_literal(compile, &literal_id, clause_index);
	if (ret < 0) {
		log_error(hier->logger, MODULE_HIERARCHY,
				  "Remove group %d vt_id %d from clause %d of compile %d failed, literal is not in compile.",
				  group_id, vt_id, clause_index, compile_id);
		goto error_out;
	}

	if (0 == compile->actual_clause_num && !compile->user_data) {		
		HASH_DEL(hier->hash_compile_by_id, compile);
		maat_garbage_bagging(hier->ref_garbage_bin, compile, (void (*)(void*))maat_hierarchy_compile_free);
	}
	pthread_rwlock_unlock(&hier->rwlock);
	return 0;
	
error_out:
	pthread_rwlock_unlock(&hier->rwlock);
	return -1;
}

int maat_hierarchy_add_group_to_group(struct maat_hierarchy *hier, int group_id, int superior_group_id)
{
	igraph_integer_t edge_id;
	struct maat_hierarchy_group *group = NULL, *superior_group = NULL;

	pthread_rwlock_wrlock(&hier->rwlock);
	hier->changed_flag = 1;
	HASH_FIND(hh_group_id, hier->hash_group_by_id, &group_id, sizeof(group_id), group);
	if (!group) {
		group = maat_hierarchy_group_new(hier, group_id);
	}
	
	HASH_FIND(hh_group_id, hier->hash_group_by_id, &superior_group_id, sizeof(superior_group_id), superior_group);
	if (!superior_group) {
		superior_group = maat_hierarchy_group_new(hier, superior_group_id);
	}

	int ret = igraph_get_eid(&hier->group_graph, &edge_id, group->vertex_id, superior_group->vertex_id, IGRAPH_DIRECTED, /*error*/ 0);
    //No duplicated edges between two groups.
	if (edge_id > 0) {
		log_error(hier->logger, MODULE_HIERARCHY,
				  "Add group %d to group %d failed, relation already exisited.",
				  group->group_id, superior_group->group_id);
		ret = -1;
	} else {
		igraph_add_edge(&hier->group_graph, group->vertex_id, superior_group->vertex_id);
		group->ref_by_superior_group_cnt++;
		superior_group->ref_by_subordinate_group_cnt++;
		ret = 0;
	}
	pthread_rwlock_unlock(&hier->rwlock);

	return ret;
}

int maat_hierarchy_remove_group_from_group(struct maat_hierarchy *hier, int group_id, int superior_group_id)
{   
	struct maat_hierarchy_group *group = NULL, *superior_group = NULL;

	//No hash write operation, LOCK protection is unnecessary.
	hier->changed_flag = 1;
	HASH_FIND(hh_group_id, hier->hash_group_by_id, &group_id, sizeof(group_id), group);
	if (NULL == group) {
		log_error(hier->logger, MODULE_HIERARCHY,
				  "Del group %d from group %d failed, group %d not exisited.",
				  group_id, superior_group_id, group_id);
		return -1;	
	}

	HASH_FIND(hh_group_id, hier->hash_group_by_id, &superior_group_id, sizeof(superior_group_id), superior_group);
	if (NULL == superior_group) {
		log_error(hier->logger, MODULE_HIERARCHY,
				  "Del group %d from group %d failed, superior group %d not exisited.",
				  group_id, superior_group_id, superior_group_id);
		return -1;	
	}

	igraph_es_t es;
	igraph_integer_t edge_num_before = 0, edge_num_after = 0;

	edge_num_before = igraph_ecount(&hier->group_graph);
	// The edges between the given pairs of vertices will be included in the edge selection.
	//The vertex pairs must be given as the arguments of the function call, the third argument 
	//is the first vertex of the first edge, the fourth argument is the second vertex of the 
	//first edge, the fifth is the first vertex of the second edge and so on. The last element
	//of the argument list must be -1 to denote the end of the argument list.
	//https://igraph.org/c/doc/igraph-Iterators.html#igraph_es_pairs_small
	int ret = igraph_es_pairs_small(&es, IGRAPH_DIRECTED, group->vertex_id, superior_group->vertex_id, -1);
	assert(ret == IGRAPH_SUCCESS);
	// ignore no such edge to abort().
	igraph_set_error_handler(igraph_error_handler_ignore);
	ret = igraph_delete_edges(&hier->group_graph, es);
	edge_num_after = igraph_ecount(&hier->group_graph);
	igraph_es_destroy(&es);
	
	if (ret != IGRAPH_SUCCESS || edge_num_before - edge_num_after != 1) {
		assert(0);
		return -1;
	}

	group->ref_by_superior_group_cnt--;
	superior_group->ref_by_subordinate_group_cnt--;

	return 0;
}

int maat_hierarchy_add_region_to_group(struct maat_hierarchy *hier, int group_id, int region_id, 
                                       int table_id, void *user_data)
{
    //A region rule belongs to ONE group only.
	struct maat_hierarchy_group *group = NULL;
	struct maat_hierarchy_region *region = NULL;
	int ret = 0;
	
	pthread_rwlock_wrlock(&hier->rwlock);
	hier->changed_flag = 1;
	HASH_FIND(hh_group_id, hier->hash_group_by_id, &group_id, sizeof(group_id), group);
	if (!group) {
		group = maat_hierarchy_group_new(hier, group_id);
	}

	HASH_FIND_INT(hier->hash_region_by_id, &region_id, region);
	if (region) {
		log_error(hier->logger, MODULE_HIERARCHY,
				  "Add region %d to group %d failed, region already in group %d.", 
				  region_id, group_id, region->ref_parent_group->group_id);
		ret = -1;
	} else {
		region = maat_hierarchy_region_new(hier, region_id, group_id, table_id, group, user_data);
		ret = 0;
	}
	pthread_rwlock_unlock(&hier->rwlock);
	
	return ret;
}

int maat_hierarchy_remove_region_from_group(struct maat_hierarchy *hier, int group_id, int region_id)
{
    struct maat_hierarchy_group *group = NULL;
	struct maat_hierarchy_region *region = NULL;

	pthread_rwlock_wrlock(&hier->rwlock);
	hier->changed_flag =  1;
	HASH_FIND(hh_group_id, hier->hash_group_by_id, &group_id, sizeof(group_id), group);
	if (!group) {
		log_error(hier->logger, MODULE_HIERARCHY,
				  "Remove region %d from group %d failed, group is not existed.", 
				  region_id, group_id);
		goto error_out;
	}

	HASH_FIND_INT(hier->hash_region_by_id, &region_id, region);
	if (!region) {
		log_error(hier->logger, MODULE_HIERARCHY,
				  "Remove region %d from group %d failed, region is not exisited.", 
				  region_id, group_id);
		goto error_out;
	}
	
	assert(region->group_id == group->group_id);
	maat_hierarchy_region_free(hier, region);
	pthread_rwlock_unlock(&hier->rwlock);
	return 0;

error_out:
	pthread_rwlock_unlock(&hier->rwlock);
	return -1;
}