/*
 * Copyright (C) 2007-2009 Andre Noll <maan@tuebingen.mpg.de>
 *
 * Licensed under the GPL v2. For licencing details see COPYING.
 */

/** \file osl_core.h Object storage layer details, not visible to users. */

#include "rbtree.h"
#include "hash.h"

__must_check __printf_1_2 __malloc char *make_message(const char *fmt, ...);

/** Internal representation of a column of an osl table. */
struct osl_column {
	/** The memory mapping of this comumn (only used for mapped columns). */
	struct osl_object data_map;
	/** The root of the rbtree (only used for columns with rbtrees). */
	struct rb_root rbtree;
	/** The index in the array of rb nodes (only used for columns with rbtrees). */
	unsigned rbtree_num;
	/** Index for volatile_objects of struct osl_row. */
	unsigned volatile_num;
	/**
	 * Starting point of the data for this column within the index
	 * (only used for mapped columns).
	 */
	uint16_t index_offset;
	/**
	 * The hash value of the name of this column.
	 *
	 * This is only used for mapped and disk storage columns).
	 */
	HASH_TYPE name_hash[HASH_SIZE];
};

/** Internal representation of an osl table */
struct osl_table {
	/** Pointer to the table description */
	const struct osl_table_description *desc;
	/**
	 * The CURRENT_TABLE_VERSION value of the library which created the
	 * table. This value is stored in the index header at table creation
	 * time. When the table is opened, the field is initialized from the
	 * on-disk value.
	 */
	uint8_t version;
	/** The size of the index header of this table. */
	uint16_t index_header_size;
	/** Contains the mapping of the table's index file */
	struct osl_object index_map;
	/** Total number of rows, including invalid rows. */
	unsigned num_rows;
	/** Keeps track of the number of invalid rows in the table. */
	uint32_t num_invalid_rows;
	/** Number of columns of type \p OSL_MAPPED_STORAGE. */
	unsigned num_mapped_columns;
	/** Number of columns of type \p OSL_NO_STORAGE. */
	unsigned num_volatile_columns;
	/** Number of columns of type \p OSL_DISK_STORAGE. */
	unsigned num_disk_storage_columns;
	/** Number of columns with associated rbtree. */
	unsigned num_rbtrees;
	/**
	 * The number of the column that determines the name of the disk
	 * storage objects.
	 */
	unsigned disk_storage_name_column;
	/** The number of bytes of an index entry of a row. */
	unsigned row_index_size;
	/** Pointer to the internal representation of the columns. */
	struct osl_column *columns;
};

/** Internal representation of a row of an osl table */
struct osl_row {
	/**
	 * The row number.
	 *
	 * It is only used if there is at least one mapped column.
	 */
	off_t num;
	/** Array of size \a num_volatile_columns. */
	struct osl_object *volatile_objects;
};

int read_table_desc(struct osl_object *map, struct osl_table_description *desc);
int init_table_structure(const struct osl_table_description *desc,
		struct osl_table **table_ptr);
int row_is_invalid(struct osl_table *t, uint32_t row_num);
int get_mapped_object(const struct osl_table *t, unsigned col_num,
	uint32_t row_num, struct osl_object *obj);
int unmap_table(struct osl_table *t, enum osl_close_flags flags);
int init_rbtrees(struct osl_table *t);

/**
 * Flags to be specified for map_table().
 *
 * \sa map_table().
 */
enum map_table_flags {
	/**
	 * Check whether the entries in the table index match the entries in
	 * the table description.
 	 */
	MAP_TBL_FL_VERIFY_INDEX = 1,
	/** Do not complain even if the dirty flag is set. */
	MAP_TBL_FL_IGNORE_DIRTY = 2,
	/** Use read-only mappings. */
	MAP_TBL_FL_MAP_RDONLY = 4
};

int map_table(struct osl_table *t, enum map_table_flags flags);
void clear_rbtrees(struct osl_table *t);
int mark_row_invalid(struct osl_table *t, uint32_t row_num);


/**
 * Get the description of a column by column number
 *
 * \param d Pointer to the table description.
 * \param col_num The number of the column to get the description for.
 *
 * \return The table description.
 *
 * \sa struct osl_column_description.
 */
_static_inline_ struct osl_column_description *get_column_description(
		const struct osl_table_description *d, unsigned col_num)
{
	return &d->column_descriptions[col_num];
}

/**
 * Format of the header of the index file of an osl table.
 *
 * Bytes 16-31 are currently unused.
 *
 * \sa enum index_column_desc_offsets, HASH_SIZE, osl_table_flags.
 */
enum index_header_offsets {
	/** Bytes 0-8: PARASLASH. */
	IDX_OSL_MAGIC = 0,
	/** Byte 9: Dirty flag (nonzero if table is mapped). */
	IDX_DIRTY_FLAG = 9,
	/** Byte 10: osl table version number. */
	IDX_VERSION = 10,
	/** Byte 11: Table flags.*/
	IDX_TABLE_FLAGS = 11,
	/** Byte 12,13: Number of columns. */
	IDX_NUM_COLUMNS,
	/** Byte 14,15 Size of the index header. */
	IDX_HEADER_SIZE = 14,
	/** Column descriptions start here. */
	IDX_COLUMN_DESCRIPTIONS = 32
};

/**
 * Format of the column description in the index header.
 *
 * \sa index_header_offsets.
 */
enum index_column_desc_offsets {
	/** Bytes 0,1: Storage_type. */
	IDX_CD_STORAGE_TYPE = 0,
	/** Bytes 2,3: Storage_flags. */
	IDX_CD_STORAGE_FLAGS = 2,
	/** Bytes 4 - 7: Data_size (only used for fixed size columns). */
	IDX_CD_DATA_SIZE = 4,
	/** Bytes 8 - ... Name of the column. */
	IDX_CD_NAME = 8,
};

/** Magic string contained in the header of the index file of each osl table. */
#define OSL_MAGIC "PARASLASH"

/**
 * The minimal number of bytes for a column in the index header.
 *
 * The column name starts at byte IDX_CD_NAME and must at least contain one
 * character, plus the terminating NULL byte.
  */
#define MIN_IDX_COLUMN_DESCRIPTION_SIZE (IDX_CD_NAME + 2)

/**
 * Get the number of bytes used for a column in the index header.
 *
 * \param name The name of the column.
 *
 * The amount of space used for a column in the index header of a table depends
 * on the (length of the) name of the column.
 *
 * \return The total number of bytes needed to store one column of this name.
 */
_static_inline_ size_t index_column_description_size(const char *name)
{
	return MIN_IDX_COLUMN_DESCRIPTION_SIZE + strlen(name) - 1;
}

/*
 * The version used by this instance of the library. Written to the index of
 * newly created tables.
 */
#define CURRENT_TABLE_VERSION 3

/*
 * The lowest table version this library understands. On open, if
 * current_version(table) < min_version(lib) the osl_open_table() call
 * fails.
 */
#define MIN_TABLE_VERSION 1


/** An index header must be at least that many bytes long. */
#define MIN_INDEX_HEADER_SIZE(num_cols) (MIN_IDX_COLUMN_DESCRIPTION_SIZE \
	* num_cols + IDX_COLUMN_DESCRIPTIONS)

/**
 * Get the number of rows from the size of the memory mapping.
 *
 * \param t Pointer to an open table.
 *
 * \return The number of rows, including invalid rows.
 */
_static_inline_ unsigned table_num_rows(const struct osl_table *t)
{
	return (t->index_map.size - t->index_header_size)
		/ t->row_index_size;
}

/**
 * Get the path of the index file from a table description.
 *
 * \param d The table description.
 *
 * \return The full path of the index file. Result must be freed by
 * the caller.
 */
_static_inline_ char *index_filename(const struct osl_table_description *d)
{
	return make_message("%s/%s/index", d->dir, d->name);
}

/**
 * Get the path of storage of a column.
 *
 * \param t Pointer to an initialized table.
 * \param col_num The number of the column to get the path for.
 *
 * \return The full path of the mapped data file (mapped storage) or the
 * data directory (disk storage). Result must be freed by the caller.
 *
 * \sa osl_storage_type.
 */
_static_inline_ char *column_filename(const struct osl_table *t, unsigned col_num)
{
	char asc[2 * HASH_SIZE + 1];
	hash_to_asc(t->columns[col_num].name_hash, asc);
	return make_message("%s/%s/%s", t->desc->dir, t->desc->name, asc);
}

/**
 * Get the start of an index entry
 *
 * \param t Pointer to a table which has been mapped.
 * \param row_num The number of the row whose index entry should be retrieved.
 * \param row_index Result pointer.
 *
 * \return Positive on success, \p -E_INDEX_CORRUPTION otherwise.
 *
 * \sa get_cell_index().
 */
_static_inline_ int get_row_index(const struct osl_table *t, uint32_t row_num,
		char **row_index)
{
	uint32_t index_offset;
	index_offset = t->index_header_size + t->row_index_size * row_num;
	if (index_offset + 8 > t->index_map.size) {
		*row_index = NULL;
		return -E_OSL_INDEX_CORRUPTION;
	}
	*row_index = (char *)(t->index_map.data) + index_offset;
	return 1;
}

/**
 * Get the index entry of a row/column pair.
 *
 * \param t Pointer to a table which has been mapped.
 * \param row_num The number of the row whose index entry should be retrieved.
 * \param col_num The number of the column whose index entry should be retrieved.
 * \param cell_index Result pointer.
 *
 * \return Positive on success, \p -E_INDEX_CORRUPTION otherwise.
 *
 * \sa get_row_index().
 */
_static_inline_ int get_cell_index(const struct osl_table *t, uint32_t row_num,
		uint32_t col_num, char **cell_index)
{
	int ret = get_row_index(t, row_num, cell_index);
	if (ret < 0)
		return ret;
	*cell_index += t->columns[col_num].index_offset;
	return ret;
}

/**
 * Change an index entry of a column after object was added.
 *
 * \param row_index Pointer to the index of the row to update.
 * \param col Pointer to the column.
 * \param map_size The new size of the data file.
 * \param object_size The size of the object just appended to the data file.
 *
 * This is called right after an object was appended to the data file for a
 * mapped column.
 *
 * \sa get_row_index().
 */
_static_inline_ void update_cell_index(char *row_index, struct osl_column *col,
		uint32_t map_size, uint32_t object_size)
{
	write_u32(row_index + col->index_offset, map_size - object_size);
	write_u32(row_index + col->index_offset + 4, object_size);
}

/**
 * Get the full path of a disk storage object
 *
 * \param t Pointer to an initialized table.
 * \param col_num The number of the column the disk storage object belongs to.
 * \param ds_name The disk storage name of the object.
 *
 * \return Pointer to the full path which must be freed by the caller.
 *
 * \sa column_filename(), disk_storage_name_of_row().
 */
_static_inline_ char *disk_storage_path(const struct osl_table *t,
		unsigned col_num, const char *ds_name)
{
	char *filename, *dirname = column_filename(t, col_num);

	if (!dirname)
		return NULL;
	filename = make_message("%s/%s", dirname, ds_name);
	free(dirname);
	return filename;
}

/**
 * Get the column description of the next column of a given type.
 *
 * \param type the desired storage type.
 * \param col_num the column to start the search.
 * \param t the osl table.
 * \param cd result is returned here.
 *
 * \return On success, \a cd contains the column description of the next column
 * of type \a type, and the number of that column is returned.  Otherwise, \a
 * cd is set to \p NULL and the function returns t->num_columns + 1.
 *
 * \sa FOR_EACH_COLUMN_OF_TYPE, FOR_EACH_MAPPED_COLUMN, FOR_EACH_RBTREE_COLUMN,
 * FOR_EACH_DISK_STORAGE_COLUMN, FOR_EACH_VOLATILE_COLUMN, osl_storage_type.
 */
_static_inline_ unsigned next_column_of_type(enum osl_storage_type type,
		unsigned col_num, const struct osl_table *t,
		const struct osl_column_description **cd)
{
	*cd = NULL;
	while (col_num < t->desc->num_columns) {
		*cd = get_column_description(t->desc, col_num);
		if ((*cd)->storage_type == type)
			break;
		col_num++;
	}
	return col_num;
}

/**
 * Find the next column with an associated rbtree.
 *
 * \param col_num The column to start the search.
 * \param t The osl table.
 * \param cd Result is returned here.

 * \return On success, \a cd contains the column description of the next column
 * with associated rbtree, and the number of that column is returned.
 * Otherwise, \a cd is set to \p NULL and the function returns t->num_columns +
 * 1.
 *
 * \sa FOR_EACH_COLUMN_OF_TYPE, FOR_EACH_MAPPED_COLUMN, FOR_EACH_RBTREE_COLUMN,
 * FOR_EACH_DISK_STORAGE_COLUMN, FOR_EACH_VOLATILE_COLUMN, osl_storage_flags.
 */
_static_inline_ int next_rbtree_column(int col_num, const struct osl_table *t,
		const struct osl_column_description **cd)
{
	*cd = NULL;
	while (col_num < t->desc->num_columns) {
		*cd = get_column_description(t->desc, col_num);
		if ((*cd)->storage_flags & OSL_RBTREE)
			break;
		col_num++;
	}
	return col_num;
}


/* quite some dirty hacks */

/** Round up size of struct osl_row to multiple of 8 */
#define RB_NODES_OFFSET ((sizeof(struct osl_row) + 7) / 8 * 8)

/**
 * Allocate a new osl row.
 *
 * \param num_rbtrees The number of rbtrees for this row.
 *
 * \return A pointer to a zeroed-out area suitable for holding an osl row with
 * \a num_rbtrees rbtree columns or \p NULL if no memory could be allocated.
 */
_static_inline_ struct osl_row *allocate_row(unsigned num_rbtrees)
{
	size_t s = RB_NODES_OFFSET + num_rbtrees * sizeof(struct rb_node);
	return calloc(1, s);
}

/**
 * Compute the pointer to a rbtree node embedded in a osl row.
 *
 * \param row The row to extract the rbtree pointer from.
 * \param rbtree_num The number of the rbtree node to extract.
 *
 * \return A pointer to the \a rbtree_num th node contained in \a row.
 */
_static_inline_ struct rb_node *get_rb_node_pointer(const struct osl_row *row, uint32_t rbtree_num)
{
	return ((struct rb_node *)(((char *)row) + RB_NODES_OFFSET)) + rbtree_num;
}

/**
 * Get a pointer to the struct containing the given rbtree node.
 *
 * \param node Pointer to the rbtree node.
 * \param rbtree_num Number of \a node in the array of rbtree nodes.
 *
 * \return A pointer to the row containing \a node.
 */
_static_inline_ struct osl_row *get_row_pointer(const struct rb_node *node,
		unsigned rbtree_num)
{
	node -= rbtree_num;
	return (struct osl_row *)(((char *)node) - RB_NODES_OFFSET);
}

/**
 * Compute a cryptographic hash of an osl object.
 *
 * \param t Determines the hash function to use.
 * \param obj the Object to compute the hash value from.
 * \param hash Result is returned here.
 */
_static_inline_ void hash_object(const struct osl_table *t,
		const struct osl_object *obj, HASH_TYPE *hash)
{
	hash_function(t->version, obj->data, obj->size, hash);
}

/**
 * Get the relative path of an object, given the hash value.
 *
 * \param t Pointer to an initialized osl table.
 * \param hash An arbitrary hash value.
 *
 * This function is typically called with \a hash being the hash of the object
 * stored in the disk storage name column of a row.  If the OSL_LARGE_TABLE
 * flag is set, the first two hex digits get separated with a slash from the
 * remaining digits.
 *
 * \return The relative path for all disk storage objects corresponding to \a
 * hash.
 *
 * \sa struct osl_table:disk_storage_name_column.
 */
_static_inline_ char *disk_storage_name_of_hash(const struct osl_table *t, HASH_TYPE *hash)
{
	char asc[2 * HASH_SIZE + 2];

	hash_to_asc(hash, asc);
	if (t->desc->flags & OSL_LARGE_TABLE)
		return make_message("%.2s/%s", asc, asc + 2);
	return strdup(asc);
}

/**
 * Iterate over each column of an initialized table.
 *
 * \param col A pointer to a struct osl_column.
 * \param desc Pointer to the table description.
 * \param cd Pointer to struct osl_column_description.
 *
 * On each iteration, \a col will point to the next column of the table and \a
 * cd will point to the column description of this column.
 *
 * \sa struct osl_column FOR_EACH_RBTREE_COLUMN, FOR_EACH_COLUMN_OF_TYPE,
 * FOR_EACH_MAPPED_COLUMN, FOR_EACH_DISK_STORAGE_COLUMN,
 * FOR_EACH_VOLATILE_COLUMN.
 */
#define FOR_EACH_COLUMN(col, desc, cd) \
	for (col = 0; col < (desc)->num_columns && \
		(cd = get_column_description(desc, col)); col++)

/**
 * Iterate over each column with associated rbtree.
 *
 * \param col Same meaning as in FOR_EACH_COLUMN().
 * \param table Same meaning as in FOR_EACH_COLUMN().
 * \param cd Same meaning as in FOR_EACH_COLUMN().
 *
 * \sa osl_storage_flags::OSL_RBTREE, FOR_EACH_COLUMN, FOR_EACH_COLUMN_OF_TYPE,
 * FOR_EACH_MAPPED_COLUMN, FOR_EACH_DISK_STORAGE_COLUMN,
 * FOR_EACH_VOLATILE_COLUMN.
 */
#define FOR_EACH_RBTREE_COLUMN(col, table, cd) \
	for (col = next_rbtree_column(0, table, &cd); \
	col < table->desc->num_columns; \
	col = next_rbtree_column(++col, table, &cd))

/**
 * Iterate over each column of given storage type.
 *
 * \param type The osl_storage_type to iterate over.
 * \param col Same meaning as in FOR_EACH_COLUMN().
 * \param table Same meaning as in FOR_EACH_COLUMN().
 * \param cd Same meaning as in FOR_EACH_COLUMN().
 *
 * \sa osl_storage_type, FOR_EACH_COLUMN, FOR_EACH_RBTREE_COLUMN,
 * FOR_EACH_MAPPED_COLUMN, FOR_EACH_DISK_STORAGE_COLUMN,
 * FOR_EACH_VOLATILE_COLUMN.
 */
#define FOR_EACH_COLUMN_OF_TYPE(type, col, table, cd) \
	for (col = next_column_of_type(type, 0, table, &cd); \
	col < table->desc->num_columns; \
	col = next_column_of_type(type, ++col, table, &cd))

/**
 * Iterate over each mapped column.
 *
 * \param col Same meaning as in FOR_EACH_COLUMN().
 * \param table Same meaning as in FOR_EACH_COLUMN().
 * \param cd Same meaning as in FOR_EACH_COLUMN().
 *
 * Just like FOR_EACH_COLUMN(), but skip columns which are
 * not of type \p OSL_MAPPED_STORAGE.
 *
 * \sa osl_storage_flags::OSL_MAPPED_STORAGE, FOR_EACH_COLUMN,
 * FOR_EACH_RBTREE_COLUMN, FOR_EACH_COLUMN_OF_TYPE,
 * FOR_EACH_DISK_STORAGE_COLUMN, FOR_EACH_VOLATILE_COLUMN.
 */
#define FOR_EACH_MAPPED_COLUMN(col, table, cd) \
	FOR_EACH_COLUMN_OF_TYPE(OSL_MAPPED_STORAGE, col, table, cd)

/**
 * Iterate over each disk storage column.
 *
 * \param col Same meaning as in FOR_EACH_COLUMN().
 * \param table Same meaning as in FOR_EACH_COLUMN().
 * \param cd Same meaning as in FOR_EACH_COLUMN().
 *
 * Just like FOR_EACH_COLUMN(), but skip columns which are
 * not of type \p OSL_DISK_STORAGE.
 *
 * \sa osl_storage_flags::OSL_DISK_STORAGE, FOR_EACH_COLUMN,
 * FOR_EACH_RBTREE_COLUMN, FOR_EACH_COLUMN_OF_TYPE, FOR_EACH_MAPPED_COLUMN,
 * FOR_EACH_VOLATILE_COLUMN.
 */
#define FOR_EACH_DISK_STORAGE_COLUMN(col, table, cd) \
	FOR_EACH_COLUMN_OF_TYPE(OSL_DISK_STORAGE, col, table, cd)

/**
 * Iterate over each volatile column.
 *
 * \param col Same meaning as in FOR_EACH_COLUMN().
 * \param table Same meaning as in FOR_EACH_COLUMN().
 * \param cd Same meaning as in FOR_EACH_COLUMN().
 *
 * Just like FOR_EACH_COLUMN(), but skip columns which are
 * not of type \p OSL_NO_STORAGE.
 *
 * \sa osl_storage_flags::OSL_NO_STORAGE, FOR_EACH_COLUMN,
 * FOR_EACH_RBTREE_COLUMN, FOR_EACH_COLUMN_OF_TYPE, FOR_EACH_MAPPED_COLUMN,
 * FOR_EACH_DISK_STORAGE_COLUMN.
 */
#define FOR_EACH_VOLATILE_COLUMN(col, table, cd) \
	FOR_EACH_COLUMN_OF_TYPE(OSL_NO_STORAGE, col, table, cd)