--- /dev/null
+#include <sys/mman.h>
+/*
+ * Copyright (C) 2007-2008 Andre Noll <maan@systemlinux.org>
+ *
+ * Licensed under the GPL v2. For licencing details see COPYING.
+ */
+
+/** \file osl.h User interface for the object storage layer. */
+
+/** describes an object of the object storage layer (osl) */
+struct osl_object {
+ /** Pointer to the data of the object. */
+ void *data;
+ /** The object's size. */
+ size_t size;
+};
+
+/** Flags that change the internal handling of osl tables. */
+enum osl_table_flags {
+ /** This table will have many rows. */
+ OSL_LARGE_TABLE = 1
+};
+
+/** The three different types of storage for an osl column */
+enum osl_storage_type {
+ /**
+ * All data for this column is stored in one file which gets mmapped by
+ * osl_open_table(). This is suitable for columns that do not hold much
+ * data.
+ */
+ OSL_MAPPED_STORAGE,
+ /**
+ * Each entry is stored on disk and is loaded on demand by
+ * open_disk_object(). This is the preferable storage type for large
+ * objects that need not be in memory all the time.
+ */
+ OSL_DISK_STORAGE,
+ /**
+ * Objects for columns of this type are volatile: They are only stored
+ * in memory and are discarded once the table gets closed.
+ */
+ OSL_NO_STORAGE
+};
+
+/**
+ * Additional per-column flags
+ */
+enum osl_storage_flags {
+ /**
+ * Build an rbtree for this column. This is only possible if the
+ * storage type of the column is either \a OSL_MAPPED_STORAGE or \a
+ * OSL_NO_STORAGE. In order to lookup objects in the table by using \a
+ * osl_get_row(), the lookup column must have an associated rbtree.
+ *
+ * \sa osl_storage_type, osl_get_row()
+ */
+ OSL_RBTREE = 1,
+ /** The data for this column will have constant size. */
+ OSL_FIXED_SIZE = 2,
+ /** All values of this column will be different. */
+ OSL_UNIQUE = 4,
+ /** Do not free the data for this column (\p OSL_NO_STORAGE). */
+ OSL_DONT_FREE = 8
+};
+
+struct osl_table;
+struct osl_row;
+
+/**
+ * In order to build up an rbtree a compare function for the objects must be
+ * specified. Such a function always takes pointers to the two objects to be
+ * compared. It must return -1, zero, or 1, if the first argument is considered
+ * to be respectively less than, equal to, or greater than the second. If two
+ * members compare as equal, their order in the sorted array is undefined.
+ */
+typedef int osl_compare_func(const struct osl_object *obj1,
+ const struct osl_object *obj2);
+typedef int osl_rbtree_loop_func(struct osl_row *row, void *data);
+
+osl_compare_func osl_hash_compare, uint32_compare;
+
+/**
+ * Describes one column of a osl table.
+ */
+struct osl_column_description {
+ /** One of zje tree possible types of storage */
+ enum osl_storage_type storage_type;
+ /** Specifies further properties of the column */
+ enum osl_storage_flags storage_flags;
+ /**
+ * The column name determines the name of the directory where all data
+ * for this column will be stored. Its hash is stored in the table
+ * header. This field is ignored if the storage type is \a NO_STORAGE
+ */
+ char *name;
+ /**
+ * For columns with an associated rbtree, this must point to a function
+ * that compares the values of two objects, either a built-in function
+ * or a function defined by the application may be supplied. This
+ * field is ignored if the column does not have an associated rbtree.
+ *
+ * \sa osl_storage_flags, osl_compare_func
+ */
+ osl_compare_func *compare_function;
+ /**
+ * If the \a OSL_FIXED_SIZE flag is set for this column, this value
+ * determines the fixed size of all objects of this column. It is
+ * ignored, if \a OSL_FIXED_SIZE is not set.
+ */
+ uint32_t data_size;
+};
+
+/**
+ * Describes one osl table.
+ */
+struct osl_table_description {
+ /** The directory which contains all files of this table. */
+ const char *dir;
+ /**
+ * The table name. A subdirectory of \a dir called \a name is created
+ * at table creation time. It must be a valid name for a subdirectory.
+ * In particular, no slashes are allowed for \a name.
+ */
+ const char *name;
+ /** The number of columns of this table. */
+ uint16_t num_columns;
+ /** Further table-wide information. */
+ enum osl_table_flags flags;
+ /** The array describing the individual columns of the table. */
+ struct osl_column_description *column_descriptions;
+};
+
+/** Flags to be passed to \a osl_close_table(). */
+enum osl_close_flags {
+ /**
+ * The table header contains a "dirty" flag which specifies whether
+ * the table is currently open by another process. This flag specifies
+ * that the dirty flag should be cleared before closing the table.
+ */
+ OSL_MARK_CLEAN = 1,
+ /**
+ * If the table contains columns of type \a OSL_NO_STORAGE and this
+ * flag is passed to osl_close_table(), free(3) is called for each
+ * object of each column of type \a OSL_NO_STORAGE.
+ */
+ OSL_FREE_VOLATILE = 2
+};
+
+
+
+int osl_create_table(const struct osl_table_description *desc);
+int osl_open_table(const struct osl_table_description *desc,
+ struct osl_table **result);
+int osl_close_table(struct osl_table *t, enum osl_close_flags flags);
+int osl_get_row(const struct osl_table *t, unsigned col_num,
+ const struct osl_object *obj, struct osl_row **result);
+int osl_get_object(const struct osl_table *t, const struct osl_row *row,
+ unsigned col_num, struct osl_object *object);
+int osl_open_disk_object(const struct osl_table *t,
+ const struct osl_row *r, unsigned col_num, struct osl_object *obj);
+int osl_close_disk_object(struct osl_object *obj);
+int osl_add_and_get_row(struct osl_table *t, struct osl_object *objects,
+ struct osl_row **row);
+int osl_add_row(struct osl_table *t, struct osl_object *objects);
+int osl_del_row(struct osl_table *t, struct osl_row *row);
+int osl_rbtree_loop(const struct osl_table *t, unsigned col_num,
+ void *private_data, osl_rbtree_loop_func *func);
+int osl_rbtree_loop_reverse(const struct osl_table *t, unsigned col_num,
+ void *private_data, osl_rbtree_loop_func *func);
+int osl_update_object(struct osl_table *t, const struct osl_row *r,
+ unsigned col_num, struct osl_object *obj);
+int osl_get_num_rows(const struct osl_table *t, unsigned *num_rows);
+int osl_rbtree_first_row(const struct osl_table *t, unsigned col_num,
+ struct osl_row **result);
+int osl_rbtree_last_row(const struct osl_table *t, unsigned col_num,
+ struct osl_row **result);
+int osl_get_nth_row(const struct osl_table *t, unsigned col_num,
+ unsigned n, struct osl_row **result);
+int osl_get_rank(const struct osl_table *t, struct osl_row *r,
+ unsigned col_num, unsigned *rank);
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