lbbs/src/section_list.c

/***************************************************************************
                                           section_list.c  -  description
                                                         -------------------
        Copyright            : (C) 2004-2025 by Leaflet
        Email                : leaflet@leafok.com
 ***************************************************************************/

/***************************************************************************
 *                                                                         *
 *   This program is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation; either version 3 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 ***************************************************************************/

#include "section_list.h"
#include "log.h"
#include "trie_dict.h"
#include <stdio.h>
#include <string.h>
#include <signal.h>
#include <unistd.h>
#include <stdlib.h>
#include <errno.h>
#include <sys/shm.h>
#include <sys/ipc.h>

// ARTICLE_BLOCK_PER_SHM * ARTICLE_BLOCK_SHM_COUNT_LIMIT should be
// no less than BBS_article_block_limit_per_section * BBS_max_section,
// in order to allocate enough memory for blocks
#define ARTICLE_BLOCK_PER_SHM 400 // sizeof(ARTICLE_BLOCK) * ARTICLE_BLOCK_PER_SHM is the size of each shm segment to allocate
#define ARTICLE_BLOCK_SHM_COUNT_LIMIT 256 // limited by length (8-bit) of proj_id in ftok(path, proj_id)

struct article_block_shm_t
{
        int shmid;
        void *p_shm;
};
typedef struct article_block_shm_t ARTICLE_BLOCK_SHM;

static ARTICLE_BLOCK_SHM *p_article_block_shm_pool;
static int article_block_shm_count;
static ARTICLE_BLOCK *p_article_block_free_list;

static SECTION_DATA *p_section_data_pool;
static int section_data_count;
static TRIE_NODE *p_trie_dict_section_data;

int section_data_pool_init(const char *filename, int article_block_count)
{
        int shmid;
        int proj_id;
        key_t key;
        size_t size;
        void *p_shm;
        int i;
        int article_block_count_in_shm;
        ARTICLE_BLOCK *p_article_block_in_shm;
        ARTICLE_BLOCK **pp_article_block_next;

        if (p_article_block_shm_pool != NULL ||
                p_article_block_free_list != NULL ||
                p_section_data_pool != NULL ||
                p_trie_dict_section_data != NULL)
        {
                log_error("section_data_pool already initialized\n");
                return -1;
        }

        if (article_block_count > ARTICLE_BLOCK_PER_SHM * ARTICLE_BLOCK_SHM_COUNT_LIMIT)
        {
                log_error("article_block_count exceed limit %d\n", ARTICLE_BLOCK_PER_SHM * ARTICLE_BLOCK_SHM_COUNT_LIMIT);
                return -2;
        }

        p_article_block_shm_pool = calloc((size_t)article_block_count / ARTICLE_BLOCK_PER_SHM + 1, sizeof(ARTICLE_BLOCK_SHM));
        if (p_article_block_shm_pool == NULL)
        {
                log_error("calloc(%d ARTICLE_BLOCK_SHM) OOM\n", article_block_count / ARTICLE_BLOCK_PER_SHM + 1);
                return -2;
        }

        p_section_data_pool = calloc(BBS_max_section, sizeof(SECTION_DATA));
        if (p_section_data_pool == NULL)
        {
                log_error("calloc(%d SECTION_DATA) OOM\n", BBS_max_section);
                return -2;
        }
        section_data_count = 0;

        p_trie_dict_section_data = trie_dict_create();
        if (p_trie_dict_section_data == NULL)
        {
                log_error("trie_dict_create() OOM\n", BBS_max_section);
                return -2;
        }

        // Allocate shared memory
        article_block_shm_count = 0;
        pp_article_block_next = &p_article_block_free_list;

        while (article_block_count > 0)
        {
                article_block_count_in_shm =
                        (article_block_count < ARTICLE_BLOCK_PER_SHM ? article_block_count : ARTICLE_BLOCK_PER_SHM);
                article_block_count -= article_block_count_in_shm;

                proj_id = getpid() + article_block_shm_count;
                key = ftok(filename, proj_id);
                if (key == -1)
                {
                        log_error("ftok(%s, %d) error (%d)\n", filename, proj_id, errno);
                        section_data_pool_cleanup();
                        return -3;
                }

                size = sizeof(shmid) + sizeof(ARTICLE_BLOCK) * (size_t)article_block_count_in_shm;
                shmid = shmget(key, size, IPC_CREAT | IPC_EXCL | 0600);
                if (shmid == -1)
                {
                        log_error("shmget(shm_index = %d, size = %d) error (%d)\n", article_block_shm_count, size, errno);
                        section_data_pool_cleanup();
                        return -3;
                }
                p_shm = shmat(shmid, NULL, 0);
                if (p_shm == (void *)-1)
                {
                        log_error("shmat(shmid = %d) error (%d)\n", shmid, errno);
                        section_data_pool_cleanup();
                        return -3;
                }

                (p_article_block_shm_pool + article_block_shm_count)->shmid = shmid;
                (p_article_block_shm_pool + article_block_shm_count)->p_shm = p_shm;
                article_block_shm_count++;

                p_article_block_in_shm = p_shm;
                *pp_article_block_next = p_article_block_in_shm;

                for (i = 0; i < article_block_count_in_shm; i++)
                {
                        if (i < article_block_count_in_shm - 1)
                        {
                                (p_article_block_in_shm + i)->p_next_block = (p_article_block_in_shm + i + 1);
                        }
                        else
                        {
                                (p_article_block_in_shm + i)->p_next_block = NULL;
                                pp_article_block_next = &((p_article_block_in_shm + i)->p_next_block);
                        }
                }
        }

        return 0;
}

void section_data_pool_cleanup(void)
{
        int i;

        if (p_trie_dict_section_data != NULL)
        {
                trie_dict_destroy(p_trie_dict_section_data);
                p_trie_dict_section_data = NULL;
                section_data_count = 0;
        }

        if (p_section_data_pool != NULL)
        {
                free(p_section_data_pool);
                p_section_data_pool = NULL;
        }

        if (p_article_block_free_list != NULL)
        {
                p_article_block_free_list = NULL;
        }

        if (p_article_block_shm_pool != NULL)
        {
                for (i = 0; i < article_block_shm_count; i++)
                {
                        if (shmdt((p_article_block_shm_pool + i)->p_shm) == -1)
                        {
                                log_error("shmdt(shmid = %d) error (%d)\n", (p_article_block_shm_pool + i)->shmid, errno);
                        }

                        if (shmctl((p_article_block_shm_pool + i)->shmid, IPC_RMID, NULL) == -1)
                        {
                                log_error("shmctl(shmid = %d, IPC_RMID) error (%d)\n", (p_article_block_shm_pool + i)->shmid, errno);
                        }
                }

                p_article_block_shm_pool = NULL;
                article_block_shm_count = 0;
        }
}

inline static ARTICLE_BLOCK *pop_free_article_block(void)
{
        ARTICLE_BLOCK *p_article_block = NULL;

        if (p_article_block_free_list != NULL)
        {
                p_article_block = p_article_block_free_list;
                p_article_block_free_list = p_article_block_free_list->p_next_block;
        }

        return p_article_block;
}

inline static void push_free_article_block(ARTICLE_BLOCK *p_article_block)
{
        p_article_block->p_next_block = p_article_block_free_list;
        p_article_block_free_list = p_article_block;
}

SECTION_DATA *section_data_create(const char *sname, const char *stitle, const char *master_name)
{
        SECTION_DATA *p_section;
        int index;

        if (p_section_data_pool == NULL || p_trie_dict_section_data == NULL)
        {
                log_error("section_data not initialized\n");
                return NULL;
        }

        if (section_data_count >= BBS_max_section)
        {
                log_error("section_data_count exceed limit %d\n", BBS_max_section);
                return NULL;
        }

        index = section_data_count;
        p_section = p_section_data_pool + index;

        strncpy(p_section->sname, sname, sizeof(p_section->sname - 1));
        p_section->sname[sizeof(p_section->sname - 1)] = '\0';

        strncpy(p_section->stitle, stitle, sizeof(p_section->stitle - 1));
        p_section->stitle[sizeof(p_section->stitle - 1)] = '\0';

        strncpy(p_section->master_name, master_name, sizeof(p_section->master_name - 1));
        p_section->master_name[sizeof(p_section->master_name - 1)] = '\0';

        p_section->p_head_block = NULL;
        p_section->p_tail_block = NULL;
        p_section->block_count = 0;
        p_section->article_count = 0;
        p_section->delete_count = 0;

        if (trie_dict_set(p_trie_dict_section_data, sname, index) != 1)
        {
                log_error("trie_dict_set(section_data, %s, %d) error\n", sname, index);
                return NULL;
        }

        section_data_count++;

        return p_section;
}

int section_data_free_block(SECTION_DATA *p_section)
{
        ARTICLE_BLOCK *p_block;

        if (p_section == NULL)
        {
                log_error("section_data_free_block() NULL pointer error\n");
                return -1;
        }

        if (p_section_data_pool == NULL)
        {
                log_error("section_data not initialized\n");
                return -1;
        }

        while (p_section->p_head_block != NULL)
        {
                p_block = p_section->p_head_block;
                p_section->p_head_block = p_block->p_next_block;
                push_free_article_block(p_block);
        }

        p_section->p_tail_block = NULL;
        p_section->block_count = 0;
        p_section->article_count = 0;
        p_section->delete_count = 0;

        return 0;
}

SECTION_DATA *section_data_find_section_by_name(const char *sname)
{
        int64_t index;

        if (p_section_data_pool == NULL || p_trie_dict_section_data == NULL)
        {
                log_error("section_data not initialized\n");
                return NULL;
        }

        if (trie_dict_get(p_trie_dict_section_data, sname, &index) != 1)
        {
                log_error("trie_dict_get(section_data, %s) error\n", sname);
                return NULL;
        }

        return (p_section_data_pool + index);
}

int section_data_append_article(SECTION_DATA *p_section, const ARTICLE *p_article)
{
        ARTICLE_BLOCK *p_block;
        int32_t last_aid = 0;
        ARTICLE *p_topic_head;
        ARTICLE *p_topic_tail;

        if (p_section == NULL || p_article == NULL)
        {
                log_error("section_data_append_article() NULL pointer error\n");
                return -1;
        }

        if (p_section_data_pool == NULL)
        {
                log_error("section_data not initialized\n");
                return -1;
        }

        if (p_section->p_tail_block == NULL || p_section->p_tail_block->article_count >= BBS_article_limit_per_block)
        {
                if (p_section->block_count >= BBS_article_block_limit_per_section)
                {
                        log_error("section block count %d reach limit\n", p_section->block_count);
                        return -2;
                }

                if ((p_block = pop_free_article_block()) == NULL)
                {
                        log_error("pop_free_article_block() error\n");
                        return -2;
                }

                p_block->article_count = 0;
                p_block->p_next_block = NULL;

                if (p_section->p_tail_block == NULL)
                {
                        p_section->p_head_block = p_block;
                        last_aid = 0;
                }
                else
                {
                        p_section->p_tail_block->p_next_block = p_block;
                        last_aid = p_section->p_tail_block->articles[BBS_article_limit_per_block - 1].aid;
                }
                p_section->p_tail_block = p_block;
                p_section->p_block[p_section->block_count] = p_block;
                p_section->block_count++;
        }
        else
        {
                p_block = p_section->p_tail_block;
                last_aid = p_block->articles[p_block->article_count - 1].aid;
        }

        // AID of articles should be strictly ascending
        if (p_article->aid <= last_aid)
        {
                log_error("section_data_append_article(aid=%d) error: last_aid=%d\n", p_article->aid, last_aid);
                return -3;
        }

        if (p_block->article_count == 0)
        {
                p_section->block_head_aid[p_section->block_count - 1] = p_article->aid;
        }

        if (p_article->tid != 0)
        {
                p_topic_head = section_data_find_article_by_aid(p_section, p_article->tid);
                if (p_topic_head == NULL)
                {
                        log_error("search head of topic (aid=%d) error\n", p_article->tid);
                        return -4;
                }

                p_topic_tail = section_data_find_article_by_aid(p_section, p_topic_head->prior_aid);
                if (p_topic_tail == NULL)
                {
                        log_error("search tail of topic (aid=%d) error\n", p_topic_head->prior_aid);
                        return -4;
                }
        }
        else
        {
                p_topic_head = &(p_block->articles[p_block->article_count]);
                p_topic_tail = p_topic_head;
        }

        // Copy article data
        p_block->articles[p_block->article_count] = *p_article;

        // Link appended article as tail node of topic bi-directional list;
        p_block->articles[p_block->article_count].prior_aid = p_topic_tail->aid;
        p_block->articles[p_block->article_count].next_aid = p_topic_head->aid;
        p_topic_head->prior_aid = p_article->aid;
        p_topic_tail->next_aid = p_article->aid;

        p_block->article_count++;
        p_section->article_count++;

        return 0;
}

ARTICLE *section_data_find_article_by_aid(SECTION_DATA *p_section, int32_t aid)
{
        ARTICLE *p_article;
        ARTICLE_BLOCK *p_block;
        int left;
        int right;
        int mid;

        if (p_section == NULL)
        {
                log_error("section_data_find_article_by_aid() NULL pointer error\n");
                return NULL;
        }

        if (p_section->block_count == 0) // empty section
        {
                return NULL;
        }

        left = 0;
        right = p_section->block_count;

        // aid in the range [ head aid of blocks[left], tail aid of blocks[right - 1] ]
        while (left < right - 1)
        {
                // get block offset no less than mid value of left and right block offsets
                mid = (left + right) / 2 + (right - left) % 2;
                
                if (mid >= BBS_article_block_limit_per_section)
                {
                        log_error("block_m(%d) is out of boundary\n", mid);
                        return NULL;
                }

                if (aid < p_section->block_head_aid[mid])
                {
                        right = mid;
                }
                else
                {
                        left = mid;
                }
        }

        p_block = p_section->p_block[left];

        left = 0;
        right = p_block->article_count - 1;

        // aid in the range [ aid of articles[left], aid of articles[right] ]
        while (left < right)
        {
                mid = (left + right) / 2;

                if (aid <= p_block->articles[mid].aid)
                {
                        right = mid;
                }
                else
                {
                        left = mid + 1;
                }
        }

        p_article = &(p_block->articles[left]);

        return p_article;
}

ARTICLE *section_data_find_article_by_index(SECTION_DATA *p_section, int index)
{
        ARTICLE *p_article;
        ARTICLE_BLOCK *p_block;

        if (p_section == NULL)
        {
                log_error("section_data_find_article_by_index() NULL pointer error\n");
                return NULL;
        }

        if (index < 0 || index >= p_section->article_count)
        {
                log_error("section_data_find_article_by_index(%d) is out of boundary [0, %d)\n", index, p_section->article_count);
                return NULL;
        }

        p_block = p_section->p_block[index / BBS_article_limit_per_block];
        p_article = &(p_block->articles[index % BBS_article_limit_per_block]);

        return p_article;
}

int section_data_mark_del_article(SECTION_DATA *p_section, int32_t aid)
{
        ARTICLE *p_article;

        if (p_section == NULL)
        {
                log_error("section_data_mark_del_article() NULL pointer error\n");
                return -2;
        }

        p_article = section_data_find_article_by_aid(p_section, aid);
        if (p_article == NULL)
        {
                return -1; // Not found
        }

        if (p_article->visible == 0)
        {
                return 0; // Already deleted
        }

        p_article->visible = 0;
        p_section->delete_count++;

        return 1;
}
1	/***************************************************************************
2	section_list.c - description
3	-------------------
4	Copyright : (C) 2004-2025 by Leaflet
5	Email : leaflet@leafok.com
6	***************************************************************************/
7
8	/***************************************************************************
9	* *
10	* This program is free software; you can redistribute it and/or modify *
11	* it under the terms of the GNU General Public License as published by *
12	* the Free Software Foundation; either version 3 of the License, or *
13	* (at your option) any later version. *
14	* *
15	***************************************************************************/
16
17	#include "section_list.h"
18	#include "log.h"
19	#include "trie_dict.h"
20	#include <stdio.h>
21	#include <string.h>
22	#include <signal.h>
23	#include <unistd.h>
24	#include <stdlib.h>
25	#include <errno.h>
26	#include <sys/shm.h>
27	#include <sys/ipc.h>
28
29	// ARTICLE_BLOCK_PER_SHM * ARTICLE_BLOCK_SHM_COUNT_LIMIT should be
30	// no less than BBS_article_block_limit_per_section * BBS_max_section,
31	// in order to allocate enough memory for blocks
32	#define ARTICLE_BLOCK_PER_SHM 400 // sizeof(ARTICLE_BLOCK) * ARTICLE_BLOCK_PER_SHM is the size of each shm segment to allocate
33	#define ARTICLE_BLOCK_SHM_COUNT_LIMIT 256 // limited by length (8-bit) of proj_id in ftok(path, proj_id)
34
35	struct article_block_shm_t
36	{
37	int shmid;
38	void *p_shm;
39	};
40	typedef struct article_block_shm_t ARTICLE_BLOCK_SHM;
41
42	static ARTICLE_BLOCK_SHM *p_article_block_shm_pool;
43	static int article_block_shm_count;
44	static ARTICLE_BLOCK *p_article_block_free_list;
45
46	static SECTION_DATA *p_section_data_pool;
47	static int section_data_count;
48	static TRIE_NODE *p_trie_dict_section_data;
49
50	int section_data_pool_init(const char *filename, int article_block_count)
51	{
52	int shmid;
53	int proj_id;
54	key_t key;
55	size_t size;
56	void *p_shm;
57	int i;
58	int article_block_count_in_shm;
59	ARTICLE_BLOCK *p_article_block_in_shm;
60	ARTICLE_BLOCK **pp_article_block_next;
61
62	if (p_article_block_shm_pool != NULL \|\|
63	p_article_block_free_list != NULL \|\|
64	p_section_data_pool != NULL \|\|
65	p_trie_dict_section_data != NULL)
66	{
67	log_error("section_data_pool already initialized\n");
68	return -1;
69	}
70
71	if (article_block_count > ARTICLE_BLOCK_PER_SHM * ARTICLE_BLOCK_SHM_COUNT_LIMIT)
72	{
73	log_error("article_block_count exceed limit %d\n", ARTICLE_BLOCK_PER_SHM * ARTICLE_BLOCK_SHM_COUNT_LIMIT);
74	return -2;
75	}
76
77	p_article_block_shm_pool = calloc((size_t)article_block_count / ARTICLE_BLOCK_PER_SHM + 1, sizeof(ARTICLE_BLOCK_SHM));
78	if (p_article_block_shm_pool == NULL)
79	{
80	log_error("calloc(%d ARTICLE_BLOCK_SHM) OOM\n", article_block_count / ARTICLE_BLOCK_PER_SHM + 1);
81	return -2;
82	}
83
84	p_section_data_pool = calloc(BBS_max_section, sizeof(SECTION_DATA));
85	if (p_section_data_pool == NULL)
86	{
87	log_error("calloc(%d SECTION_DATA) OOM\n", BBS_max_section);
88	return -2;
89	}
90	section_data_count = 0;
91
92	p_trie_dict_section_data = trie_dict_create();
93	if (p_trie_dict_section_data == NULL)
94	{
95	log_error("trie_dict_create() OOM\n", BBS_max_section);
96	return -2;
97	}
98
99	// Allocate shared memory
100	article_block_shm_count = 0;
101	pp_article_block_next = &p_article_block_free_list;
102
103	while (article_block_count > 0)
104	{
105	article_block_count_in_shm =
106	(article_block_count < ARTICLE_BLOCK_PER_SHM ? article_block_count : ARTICLE_BLOCK_PER_SHM);
107	article_block_count -= article_block_count_in_shm;
108
109	proj_id = getpid() + article_block_shm_count;
110	key = ftok(filename, proj_id);
111	if (key == -1)
112	{
113	log_error("ftok(%s, %d) error (%d)\n", filename, proj_id, errno);
114	section_data_pool_cleanup();
115	return -3;
116	}
117
118	size = sizeof(shmid) + sizeof(ARTICLE_BLOCK) * (size_t)article_block_count_in_shm;
119	shmid = shmget(key, size, IPC_CREAT \| IPC_EXCL \| 0600);
120	if (shmid == -1)
121	{
122	log_error("shmget(shm_index = %d, size = %d) error (%d)\n", article_block_shm_count, size, errno);
123	section_data_pool_cleanup();
124	return -3;
125	}
126	p_shm = shmat(shmid, NULL, 0);
127	if (p_shm == (void *)-1)
128	{
129	log_error("shmat(shmid = %d) error (%d)\n", shmid, errno);
130	section_data_pool_cleanup();
131	return -3;
132	}
133
134	(p_article_block_shm_pool + article_block_shm_count)->shmid = shmid;
135	(p_article_block_shm_pool + article_block_shm_count)->p_shm = p_shm;
136	article_block_shm_count++;
137
138	p_article_block_in_shm = p_shm;
139	*pp_article_block_next = p_article_block_in_shm;
140
141	for (i = 0; i < article_block_count_in_shm; i++)
142	{
143	if (i < article_block_count_in_shm - 1)
144	{
145	(p_article_block_in_shm + i)->p_next_block = (p_article_block_in_shm + i + 1);
146	}
147	else
148	{
149	(p_article_block_in_shm + i)->p_next_block = NULL;
150	pp_article_block_next = &((p_article_block_in_shm + i)->p_next_block);
151	}
152	}
153	}
154
155	return 0;
156	}
157
158	void section_data_pool_cleanup(void)
159	{
160	int i;
161
162	if (p_trie_dict_section_data != NULL)
163	{
164	trie_dict_destroy(p_trie_dict_section_data);
165	p_trie_dict_section_data = NULL;
166	section_data_count = 0;
167	}
168
169	if (p_section_data_pool != NULL)
170	{
171	free(p_section_data_pool);
172	p_section_data_pool = NULL;
173	}
174
175	if (p_article_block_free_list != NULL)
176	{
177	p_article_block_free_list = NULL;
178	}
179
180	if (p_article_block_shm_pool != NULL)
181	{
182	for (i = 0; i < article_block_shm_count; i++)
183	{
184	if (shmdt((p_article_block_shm_pool + i)->p_shm) == -1)
185	{
186	log_error("shmdt(shmid = %d) error (%d)\n", (p_article_block_shm_pool + i)->shmid, errno);
187	}
188
189	if (shmctl((p_article_block_shm_pool + i)->shmid, IPC_RMID, NULL) == -1)
190	{
191	log_error("shmctl(shmid = %d, IPC_RMID) error (%d)\n", (p_article_block_shm_pool + i)->shmid, errno);
192	}
193	}
194
195	p_article_block_shm_pool = NULL;
196	article_block_shm_count = 0;
197	}
198	}
199
200	inline static ARTICLE_BLOCK *pop_free_article_block(void)
201	{
202	ARTICLE_BLOCK *p_article_block = NULL;
203
204	if (p_article_block_free_list != NULL)
205	{
206	p_article_block = p_article_block_free_list;
207	p_article_block_free_list = p_article_block_free_list->p_next_block;
208	}
209
210	return p_article_block;
211	}
212
213	inline static void push_free_article_block(ARTICLE_BLOCK *p_article_block)
214	{
215	p_article_block->p_next_block = p_article_block_free_list;
216	p_article_block_free_list = p_article_block;
217	}
218
219	SECTION_DATA section_data_create(const char sname, const char stitle, const char master_name)
220	{
221	SECTION_DATA *p_section;
222	int index;
223
224	if (p_section_data_pool == NULL \|\| p_trie_dict_section_data == NULL)
225	{
226	log_error("section_data not initialized\n");
227	return NULL;
228	}
229
230	if (section_data_count >= BBS_max_section)
231	{
232	log_error("section_data_count exceed limit %d\n", BBS_max_section);
233	return NULL;
234	}
235
236	index = section_data_count;
237	p_section = p_section_data_pool + index;
238
239	strncpy(p_section->sname, sname, sizeof(p_section->sname - 1));
240	p_section->sname[sizeof(p_section->sname - 1)] = '\0';
241
242	strncpy(p_section->stitle, stitle, sizeof(p_section->stitle - 1));
243	p_section->stitle[sizeof(p_section->stitle - 1)] = '\0';
244
245	strncpy(p_section->master_name, master_name, sizeof(p_section->master_name - 1));
246	p_section->master_name[sizeof(p_section->master_name - 1)] = '\0';
247
248	p_section->p_head_block = NULL;
249	p_section->p_tail_block = NULL;
250	p_section->block_count = 0;
251	p_section->article_count = 0;
252	p_section->delete_count = 0;
253
254	if (trie_dict_set(p_trie_dict_section_data, sname, index) != 1)
255	{
256	log_error("trie_dict_set(section_data, %s, %d) error\n", sname, index);
257	return NULL;
258	}
259
260	section_data_count++;
261
262	return p_section;
263	}
264
265	int section_data_free_block(SECTION_DATA *p_section)
266	{
267	ARTICLE_BLOCK *p_block;
268
269	if (p_section == NULL)
270	{
271	log_error("section_data_free_block() NULL pointer error\n");
272	return -1;
273	}
274
275	if (p_section_data_pool == NULL)
276	{
277	log_error("section_data not initialized\n");
278	return -1;
279	}
280
281	while (p_section->p_head_block != NULL)
282	{
283	p_block = p_section->p_head_block;
284	p_section->p_head_block = p_block->p_next_block;
285	push_free_article_block(p_block);
286	}
287
288	p_section->p_tail_block = NULL;
289	p_section->block_count = 0;
290	p_section->article_count = 0;
291	p_section->delete_count = 0;
292
293	return 0;
294	}
295
296	SECTION_DATA section_data_find_section_by_name(const char sname)
297	{
298	int64_t index;
299
300	if (p_section_data_pool == NULL \|\| p_trie_dict_section_data == NULL)
301	{
302	log_error("section_data not initialized\n");
303	return NULL;
304	}
305
306	if (trie_dict_get(p_trie_dict_section_data, sname, &index) != 1)
307	{
308	log_error("trie_dict_get(section_data, %s) error\n", sname);
309	return NULL;
310	}
311
312	return (p_section_data_pool + index);
313	}
314
315	int section_data_append_article(SECTION_DATA p_section, const ARTICLE p_article)
316	{
317	ARTICLE_BLOCK *p_block;
318	int32_t last_aid = 0;
319	ARTICLE *p_topic_head;
320	ARTICLE *p_topic_tail;
321
322	if (p_section == NULL \|\| p_article == NULL)
323	{
324	log_error("section_data_append_article() NULL pointer error\n");
325	return -1;
326	}
327
328	if (p_section_data_pool == NULL)
329	{
330	log_error("section_data not initialized\n");
331	return -1;
332	}
333
334	if (p_section->p_tail_block == NULL \|\| p_section->p_tail_block->article_count >= BBS_article_limit_per_block)
335	{
336	if (p_section->block_count >= BBS_article_block_limit_per_section)
337	{
338	log_error("section block count %d reach limit\n", p_section->block_count);
339	return -2;
340	}
341
342	if ((p_block = pop_free_article_block()) == NULL)
343	{
344	log_error("pop_free_article_block() error\n");
345	return -2;
346	}
347
348	p_block->article_count = 0;
349	p_block->p_next_block = NULL;
350
351	if (p_section->p_tail_block == NULL)
352	{
353	p_section->p_head_block = p_block;
354	last_aid = 0;
355	}
356	else
357	{
358	p_section->p_tail_block->p_next_block = p_block;
359	last_aid = p_section->p_tail_block->articles[BBS_article_limit_per_block - 1].aid;
360	}
361	p_section->p_tail_block = p_block;
362	p_section->p_block[p_section->block_count] = p_block;
363	p_section->block_count++;
364	}
365	else
366	{
367	p_block = p_section->p_tail_block;
368	last_aid = p_block->articles[p_block->article_count - 1].aid;
369	}
370
371	// AID of articles should be strictly ascending
372	if (p_article->aid <= last_aid)
373	{
374	log_error("section_data_append_article(aid=%d) error: last_aid=%d\n", p_article->aid, last_aid);
375	return -3;
376	}
377
378	if (p_block->article_count == 0)
379	{
380	p_section->block_head_aid[p_section->block_count - 1] = p_article->aid;
381	}
382
383	if (p_article->tid != 0)
384	{
385	p_topic_head = section_data_find_article_by_aid(p_section, p_article->tid);
386	if (p_topic_head == NULL)
387	{
388	log_error("search head of topic (aid=%d) error\n", p_article->tid);
389	return -4;
390	}
391
392	p_topic_tail = section_data_find_article_by_aid(p_section, p_topic_head->prior_aid);
393	if (p_topic_tail == NULL)
394	{
395	log_error("search tail of topic (aid=%d) error\n", p_topic_head->prior_aid);
396	return -4;
397	}
398	}
399	else
400	{
401	p_topic_head = &(p_block->articles[p_block->article_count]);
402	p_topic_tail = p_topic_head;
403	}
404
405	// Copy article data
406	p_block->articles[p_block->article_count] = *p_article;
407
408	// Link appended article as tail node of topic bi-directional list;
409	p_block->articles[p_block->article_count].prior_aid = p_topic_tail->aid;
410	p_block->articles[p_block->article_count].next_aid = p_topic_head->aid;
411	p_topic_head->prior_aid = p_article->aid;
412	p_topic_tail->next_aid = p_article->aid;
413
414	p_block->article_count++;
415	p_section->article_count++;
416
417	return 0;
418	}
419
420	ARTICLE section_data_find_article_by_aid(SECTION_DATA p_section, int32_t aid)
421	{
422	ARTICLE *p_article;
423	ARTICLE_BLOCK *p_block;
424	int left;
425	int right;
426	int mid;
427
428	if (p_section == NULL)
429	{
430	log_error("section_data_find_article_by_aid() NULL pointer error\n");
431	return NULL;
432	}
433
434	if (p_section->block_count == 0) // empty section
435	{
436	return NULL;
437	}
438
439	left = 0;
440	right = p_section->block_count;
441
442	// aid in the range [ head aid of blocks[left], tail aid of blocks[right - 1] ]
443	while (left < right - 1)
444	{
445	// get block offset no less than mid value of left and right block offsets
446	mid = (left + right) / 2 + (right - left) % 2;
447
448	if (mid >= BBS_article_block_limit_per_section)
449	{
450	log_error("block_m(%d) is out of boundary\n", mid);
451	return NULL;
452	}
453
454	if (aid < p_section->block_head_aid[mid])
455	{
456	right = mid;
457	}
458	else
459	{
460	left = mid;
461	}
462	}
463
464	p_block = p_section->p_block[left];
465
466	left = 0;
467	right = p_block->article_count - 1;
468
469	// aid in the range [ aid of articles[left], aid of articles[right] ]
470	while (left < right)
471	{
472	mid = (left + right) / 2;
473
474	if (aid <= p_block->articles[mid].aid)
475	{
476	right = mid;
477	}
478	else
479	{
480	left = mid + 1;
481	}
482	}
483
484	p_article = &(p_block->articles[left]);
485
486	return p_article;
487	}
488
489	ARTICLE section_data_find_article_by_index(SECTION_DATA p_section, int index)
490	{
491	ARTICLE *p_article;
492	ARTICLE_BLOCK *p_block;
493
494	if (p_section == NULL)
495	{
496	log_error("section_data_find_article_by_index() NULL pointer error\n");
497	return NULL;
498	}
499
500	if (index < 0 \|\| index >= p_section->article_count)
501	{
502	log_error("section_data_find_article_by_index(%d) is out of boundary [0, %d)\n", index, p_section->article_count);
503	return NULL;
504	}
505
506	p_block = p_section->p_block[index / BBS_article_limit_per_block];
507	p_article = &(p_block->articles[index % BBS_article_limit_per_block]);
508
509	return p_article;
510	}
511
512	int section_data_mark_del_article(SECTION_DATA *p_section, int32_t aid)
513	{
514	ARTICLE *p_article;
515
516	if (p_section == NULL)
517	{
518	log_error("section_data_mark_del_article() NULL pointer error\n");
519	return -2;
520	}
521
522	p_article = section_data_find_article_by_aid(p_section, aid);
523	if (p_article == NULL)
524	{
525	return -1; // Not found
526	}
527
528	if (p_article->visible == 0)
529	{
530	return 0; // Already deleted
531	}
532
533	p_article->visible = 0;
534	p_section->delete_count++;
535
536	return 1;
537	}
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