Kill unused E_FSTAT.
[paraslash.git] / osl.h
1 #include <sys/mman.h>
2 /*
3 * Copyright (C) 2007 Andre Noll <maan@systemlinux.org>
4 *
5 * Licensed under the GPL v2. For licencing details see COPYING.
6 */
7
8 /** \file osl.h User interface for the object storage layer. */
9
10 /** describes an object of the object storage layer (osl) */
11 struct osl_object {
12 /** Pointer to the data of the object. */
13 void *data;
14 /** The object's size. */
15 size_t size;
16 };
17
18 /** Flags that change the internal handling of osl tables. */
19 enum osl_table_flags {
20 /** This table will have many rows. */
21 OSL_LARGE_TABLE = 1
22 };
23
24 /** The three different types of storage for an osl column */
25 enum osl_storage_type {
26 /**
27 * All data for this column is stored in one file which gets mmapped by
28 * osl_open_table(). This is suitable for columns that do not hold much
29 * data.
30 */
31 OSL_MAPPED_STORAGE,
32 /**
33 * Each entry is stored on disk and is loaded on demand by
34 * open_disk_object(). This is the preferable storage type for large
35 * objects that need not be in memory all the time.
36 */
37 OSL_DISK_STORAGE,
38 /**
39 * Objects for columns of this type are volatile: They are only stored
40 * in memory and are discarded once the table gets closed.
41 */
42 OSL_NO_STORAGE
43 };
44
45 /**
46 * Additional per-column flags
47 */
48 enum osl_storage_flags {
49 /**
50 * Build an rbtree for this column. This is only possible if the
51 * storage type of the column is either \a OSL_MAPPED_STORAGE or \a
52 * OSL_NO_STORAGE. In order to lookup objects in the table by using \a
53 * osl_get_row(), the lookup column must have an associated rbtree.
54 *
55 * \sa osl_storage_type, osl_get_row()
56 */
57 OSL_RBTREE = 1,
58 /** The data for this column will have constant size. */
59 OSL_FIXED_SIZE = 2,
60 /** All values of this column will be different. */
61 OSL_UNIQUE = 4,
62 /** Do not free the data for this column (\p OSL_NO_STORAGE). */
63 OSL_DONT_FREE = 8
64 };
65
66 struct osl_table;
67 struct osl_row;
68
69 /**
70 * In order to build up an rbtree a compare function for the objects must be
71 * specified. Such a function always takes pointers to the two objects to be
72 * compared. It must return -1, zero, or 1, if the first argument is considered
73 * to be respectively less than, equal to, or greater than the second. If two
74 * members compare as equal, their order in the sorted array is undefined.
75 */
76 typedef int osl_compare_func(const struct osl_object *obj1,
77 const struct osl_object *obj2);
78 typedef int osl_rbtree_loop_func(struct osl_row *row, void *data);
79
80 osl_compare_func osl_hash_compare, uint32_compare;
81
82 /**
83 * Describes one column of a osl table.
84 */
85 struct osl_column_description {
86 /** One of zje tree possible types of storage */
87 enum osl_storage_type storage_type;
88 /** Specifies further properties of the column */
89 enum osl_storage_flags storage_flags;
90 /**
91 * The column name determines the name of the directory where all data
92 * for this column will be stored. Its hash is stored in the table
93 * header. This field is ignored if the storage type is \a NO_STORAGE
94 */
95 char *name;
96 /**
97 * For columns with an associated rbtree, this must point to a function
98 * that compares the values of two objects, either a built-in function
99 * or a function defined by the application may be supplied. This
100 * field is ignored if the column does not have an associated rbtree.
101 *
102 * \sa osl_storage_flags, osl_compare_func
103 */
104 osl_compare_func *compare_function;
105 /**
106 * If the \a OSL_FIXED_SIZE flag is set for this column, this value
107 * determines the fixed size of all objects of this column. It is
108 * ignored, if \a OSL_FIXED_SIZE is not set.
109 */
110 uint32_t data_size;
111 };
112
113 /**
114 * Describes one osl table.
115 */
116 struct osl_table_description {
117 /** The directory which contains all files of this table. */
118 const char *dir;
119 /**
120 * The table name. A subdirectory of \a dir called \a name is created
121 * at table creation time. It must be a valid name for a subdirectory.
122 * In particular, no slashes are allowed for \a name.
123 */
124 const char *name;
125 /** The number of columns of this table. */
126 uint16_t num_columns;
127 /** Further table-wide information. */
128 enum osl_table_flags flags;
129 /** The array describing the individual columns of the table. */
130 struct osl_column_description *column_descriptions;
131 };
132
133 /** Flags to be passed to \a osl_close_table(). */
134 enum osl_close_flags {
135 /**
136 * The table header contains a "dirty" flag which specifies whether
137 * the table is currently open by another process. This flag specifies
138 * that the dirty flag should be cleared before closing the table.
139 */
140 OSL_MARK_CLEAN = 1,
141 /**
142 * If the table contains columns of type \a OSL_NO_STORAGE and this
143 * flag is passed to osl_close_table(), free(3) is called for each
144 * object of each column of type \a OSL_NO_STORAGE.
145 */
146 OSL_FREE_VOLATILE = 2
147 };
148
149
150
151 int osl_create_table(const struct osl_table_description *desc);
152 int osl_open_table(const struct osl_table_description *desc,
153 struct osl_table **result);
154 int osl_close_table(struct osl_table *t, enum osl_close_flags flags);
155 int osl_get_row(const struct osl_table *t, unsigned col_num,
156 const struct osl_object *obj, struct osl_row **result);
157 int osl_get_object(const struct osl_table *t, const struct osl_row *row,
158 unsigned col_num, struct osl_object *object);
159 int osl_open_disk_object(const struct osl_table *t,
160 const struct osl_row *r, unsigned col_num, struct osl_object *obj);
161 int osl_close_disk_object(struct osl_object *obj);
162 int osl_add_and_get_row(struct osl_table *t, struct osl_object *objects,
163 struct osl_row **row);
164 int osl_add_row(struct osl_table *t, struct osl_object *objects);
165 int osl_del_row(struct osl_table *t, struct osl_row *row);
166 int osl_rbtree_loop(const struct osl_table *t, unsigned col_num,
167 void *private_data, osl_rbtree_loop_func *func);
168 int osl_rbtree_loop_reverse(const struct osl_table *t, unsigned col_num,
169 void *private_data, osl_rbtree_loop_func *func);
170 int osl_update_object(struct osl_table *t, const struct osl_row *r,
171 unsigned col_num, struct osl_object *obj);
172 int osl_get_num_rows(const struct osl_table *t, unsigned *num_rows);
173 int osl_rbtree_first_row(const struct osl_table *t, unsigned col_num,
174 struct osl_row **result);
175 int osl_rbtree_last_row(const struct osl_table *t, unsigned col_num,
176 struct osl_row **result);
177 int osl_get_nth_row(const struct osl_table *t, unsigned col_num,
178 unsigned n, struct osl_row **result);
179 int osl_get_rank(const struct osl_table *t, struct osl_row *r,
180 unsigned col_num, unsigned *rank);
181
182 int for_each_file_in_dir(const char *dirname,
183 int (*func)(const char *, const void *), const void *private_data);
184 ssize_t para_write_all(int fd, const void *buf, size_t size);
185 int para_lseek(int fd, off_t *offset, int whence);
186 int para_write_file(const char *filename, const void *buf, size_t size);
187