X-Git-Url: http://git.tuebingen.mpg.de/?p=osl.git;a=blobdiff_plain;f=osl.h.in;h=2abe135d7967446643aa6a803656aaa85b754d14;hp=8c386c7bcd809d4053128b0943a98b2c90eaa66f;hb=280f5eaf389483d35af6ad9211d003ffa73cb2ac;hpb=026cd39b227af84bf84f52c40d1910dcd265b93e diff --git a/osl.h.in b/osl.h.in index 8c386c7..2abe135 100644 --- a/osl.h.in +++ b/osl.h.in @@ -1,13 +1,18 @@ -#include /* - * Copyright (C) 2007-2008 Andre Noll + * Copyright (C) 2007-2009 Andre Noll * * 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) */ +#include +#include + +/** Export all declarations in this file. */ +#pragma GCC visibility push(default) + +/** Describes an object of the object storage layer (osl) */ struct osl_object { /** Pointer to the data of the object. */ void *data; @@ -37,7 +42,7 @@ enum osl_storage_type { 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. + * in memory and are discarded when the table is closed. */ OSL_NO_STORAGE }; @@ -57,40 +62,47 @@ enum osl_storage_flags { OSL_RBTREE = 1, /** The data for this column will have constant size. */ OSL_FIXED_SIZE = 2, - /** All values of this column will be different. */ + /** All values are different. Must be set if \p OSL_RBTREE is set. */ OSL_UNIQUE = 4, /** Do not free the data for this column (\p OSL_NO_STORAGE). */ OSL_DONT_FREE = 8 }; +/** Opaque osl table structure. */ struct osl_table; +/** Opaque osl row structure. */ 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. + * provided. This function 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 rbtree 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; +/** + * The osl_rbreee_loop functions take a function pointer of this type. For each + * node in the rbtree, the given function is called. + * + * \sa osl_rbtree_loop(), osl_rbtree_loop_reverse(). + */ +typedef int osl_rbtree_loop_func(struct osl_row *row, void *data); /** * 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; + /** One of the three possible types of storage, \sa osl_storage_type. */ + uint16_t storage_type; + /** Specifies further properties of the column, \sa osl_storage_flags. */ + uint16_t 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 + * header. This field is ignored if the storage type is \a NO_STORAGE. */ char *name; /** @@ -104,7 +116,7 @@ struct osl_column_description { 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 + * describes the number of bytes of each object of this column. It is * ignored, if \a OSL_FIXED_SIZE is not set. */ uint32_t data_size; @@ -112,9 +124,17 @@ struct osl_column_description { /** * Describes one osl table. + * + * A pointer to the table description is passed to \ref osl_create_table() and + * \ref osl_open_table(). The osl library calls which operate on an open table + * refer to the fields of the table description through this pointer. Hence the + * table description must not be modified or freed before the table is closed. */ struct osl_table_description { - /** The directory which contains all files of this table. */ + /** + * The directory which contains all files of this table. This may be + * either relative to the cwd or an absolute path. + */ const char *dir; /** * The table name. A subdirectory of \a dir called \a name is created @@ -124,8 +144,8 @@ struct osl_table_description { const char *name; /** The number of columns of this table. */ uint16_t num_columns; - /** Further table-wide information. */ - enum osl_table_flags flags; + /** Further table-wide information, \sa osl_table_flags. */ + uint8_t flags; /** The array describing the individual columns of the table. */ struct osl_column_description *column_descriptions; }; @@ -133,9 +153,10 @@ struct osl_table_description { /** 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. + * The table header contains a "dirty" flag which indicates whether the + * table is currently held open by another process. The \a + * OSL_MARK_CLEAN flag instructs libosl to clear the dirty flag when + * the table is closed. */ OSL_MARK_CLEAN = 1, /** @@ -146,35 +167,336 @@ enum osl_close_flags { OSL_FREE_VOLATILE = 2 }; - - +/** + * Create a new osl table. + * + * \param desc Pointer to the table description. + * + * \return Standard. + */ int osl_create_table(const struct osl_table_description *desc); + +/** + * Open an osl table. + * + * Each osl table must be opened before its data can be accessed. + * + * \param desc Describes the table to be opened. + * \param result Contains a pointer to the open table on success. + * + * The table description given by \a desc should coincide with the + * description used at creation time. + * + * \return Standard. + */ int osl_open_table(const struct osl_table_description *desc, struct osl_table **result); + +/** + * Close an osl table. + * + * \param t Pointer to the table to be closed. + * \param flags Options for what should be cleaned up. + * + * If osl_open_table() succeeds, the resulting table pointer must later be + * passed to this function in order to flush all changes to the file system and + * to free the resources that were allocated by osl_open_table(). + * + * \return Standard. + * + * \sa osl_open_table(), unmap_table(). + */ int osl_close_table(struct osl_table *t, enum osl_close_flags flags); + +/** + * Get the row that contains the given object. + * + * \param t Pointer to an open osl table. + * \param col_num The number of the column to be searched. + * \param obj The object to be looked up. + * \param result Points to the row containing \a obj. + * + * Lookup \a obj in \a t and return the row containing \a obj. The column + * specified by \a col_num must have an associated rbtree. + * + * \return Standard. \a result is set to \p NULL if and only if the function + * returns negative. + * + * \sa osl_storage_flags + */ int osl_get_row(const struct osl_table *t, unsigned col_num, const struct osl_object *obj, struct osl_row **result); + +/** + * Retrieve an object identified by row and column. + * + * \param t Pointer to an open osl table. + * \param row Pointer to the row. + * \param col_num The column number. + * \param object The result pointer. + * + * The column determined by \a col_num must be of type \p OSL_MAPPED_STORAGE + * or \p OSL_NO_STORAGE, i.e. no disk storage objects may be retrieved by this + * function. + * + * \return Standard. + * + * \sa osl_storage_type, osl_open_disk_object(). + */ int osl_get_object(const struct osl_table *t, const struct osl_row *row, unsigned col_num, struct osl_object *object); + +/** + * Retrieve an object of type \p OSL_DISK_STORAGE by row and column. + * + * \param t Pointer to an open osl table. + * \param r Pointer to the row containing the object. + * \param col_num The column number. + * \param obj Points to the result upon successful return. + * + * For columns of type \p OSL_DISK_STORAGE, this function must be used to + * retrieve one of its containing objects. Afterwards, osl_close_disk_object() + * must be called in order to deallocate the resources. + * + * \return Standard. + * + * \sa osl_get_object(), osl_storage_type, osl_close_disk_object(). + */ int osl_open_disk_object(const struct osl_table *t, const struct osl_row *r, unsigned col_num, struct osl_object *obj); + +/** + * Free resources that were allocated during osl_open_disk_object(). + * + * \param obj Pointer to the object previously returned by open_disk_object(). + * + * \return The return value of the underlying call to munmap(). + * + * \sa munmap(2). + */ int osl_close_disk_object(struct osl_object *obj); + +/** + * Add a new row to an osl table and retrieve this row. + * + * \param t Pointer to an open osl table. + * \param objects Array of objects to be added. + * \param row Result pointer. + * + * The \a objects parameter must point to an array containing one object per + * column. The order of the objects in the array is given by the table + * description of \a table. Several sanity checks are performed during object + * insertion and the function returns without modifying the table if any of + * these tests fail. In fact, it is atomic in the sense that it either + * succeeds or leaves the table unchanged (i.e. either all or none of the + * objects are added to the table). + * + * It is considered an error if an object is added to a column with associated + * rbtree if this object is equal to an object already contained in that column + * (i.e. the compare function for the column's rbtree returns zero). + * + * \return Standard. + * + * \sa struct osl_table_description, osl_compare_func, osl_add_row(). + */ int osl_add_and_get_row(struct osl_table *t, struct osl_object *objects, struct osl_row **row); + + +/** + * Add a new row to an osl table. + * + * \param t Same meaning as osl_add_and_get_row(). + * \param objects Same meaning as osl_add_and_get_row(). + * + * \return The return value of the underlying call to osl_add_and_get_row(). + * + * This is equivalent to osl_add_and_get_row(t, objects, NULL). + */ int osl_add_row(struct osl_table *t, struct osl_object *objects); + +/** + * Delete a row from an osl table. + * + * \param t Pointer to an open osl table. + * \param row Pointer to the row to delete. + * + * This removes all disk storage objects, removes all rbtree nodes, and frees + * all volatile objects belonging to the given row. For mapped columns, the + * data is merely marked invalid and may be pruned from time to time by + * osl_fsck. + * + * \return Standard. + */ int osl_del_row(struct osl_table *t, struct osl_row *row); + +/** + * Loop over all nodes in an rbtree. + * + * \param t Pointer to an open osl table. + * \param col_num The column to use for iterating over the elements. + * \param private_data Pointer that gets passed to \a func. + * \param func The function to be called for each node in the rbtree. + * + * This function does an in-order walk of the rbtree associated with \a + * col_num. It is an error if the \p OSL_RBTREE flag is not set for this + * column. For each node in the rbtree, the given function \a func is called + * with two pointers as arguments: The first osl_row* argument points to the + * row that contains the object corresponding to the rbtree node currently + * traversed, and the \a private_data pointer is passed verbatim to \a func as the + * second argument. The loop terminates either if \a func returns a negative + * value, or if all nodes of the tree have been visited. + * + * + * \return Standard. If the termination of the loop was caused by \a func + * returning a negative value, \p -E_OSL_LOOP is returned. + * + * \sa osl_storage_flags, osl_rbtree_loop_reverse(), osl_compare_func. + */ int osl_rbtree_loop(const struct osl_table *t, unsigned col_num, void *private_data, osl_rbtree_loop_func *func); + +/** + * Loop over all nodes in an rbtree in reverse order. + * + * \param t Identical meaning as in \p osl_rbtree_loop(). + * \param col_num Identical meaning as in \p osl_rbtree_loop(). + * \param private_data Identical meaning as in \p osl_rbtree_loop(). + * \param func Identical meaning as in \p osl_rbtree_loop(). + * + * This function is identical to \p osl_rbtree_loop(), the only difference + * is that the tree is walked in reverse order. + * + * \return The same return value as \p osl_rbtree_loop(). + * + * \sa osl_rbtree_loop(). + */ int osl_rbtree_loop_reverse(const struct osl_table *t, unsigned col_num, void *private_data, osl_rbtree_loop_func *func); + +/** + * Change an object in an osl table. + * + * \param t Pointer to an open osl table. + * \param r Pointer to the row containing the object to be updated. + * \param col_num Number of the column containing the object to be updated. + * \param obj Pointer to the replacement object. + * + * This function gets rid of all references to the old object. This includes + * removal of the rbtree node in case there is an rbtree associated with \a + * col_num. It then inserts \a obj into the table and the rbtree if necessary. + * + * If the \p OSL_RBTREE flag is set for \a col_num, you \b MUST call this + * function in order to change the contents of an object, even for volatile or + * mapped columns of constant size (which may be updated directly if \p + * OSL_RBTREE is not set). Otherwise the rbtree might become corrupt. + * + * \return Standard + */ int osl_update_object(struct osl_table *t, const struct osl_row *r, unsigned col_num, struct osl_object *obj); + +/** + * Get the number of rows of the given table. + * + * \param t Pointer to an open osl table. + * \param num_rows Result is returned here. + * + * The number of rows returned via \a num_rows excluding any invalid rows. + * + * \return Positive on success, \p -E_OSL_BAD_TABLE if \a t is \p NULL. + */ int osl_get_num_rows(const struct osl_table *t, unsigned *num_rows); + + +/** + * Get the row corresponding to the smallest rbtree node of a column. + * + * \param t An open rbtree table. + * \param col_num The number of the rbtree column. + * \param result A pointer to the first row is returned here. + * + * The rbtree node of the smallest object (with respect to the corresponding + * compare function) is selected and the row containing this object is + * returned. It is an error if \a col_num refers to a column without an + * associated rbtree. + * + * \return Standard. + * + * \sa osl_get_nth_row(), osl_rbtree_last_row(). + */ int osl_rbtree_first_row(const struct osl_table *t, unsigned col_num, struct osl_row **result); + +/** + * Get the row corresponding to the greatest rbtree node of a column. + * + * \param t The same meaning as in \p osl_rbtree_first_row(). + * \param col_num The same meaning as in \p osl_rbtree_first_row(). + * \param result The same meaning as in \p osl_rbtree_first_row(). + * + * This function works just like osl_rbtree_first_row(), the only difference + * is that the row containing the greatest rather than the smallest object is + * returned. + * + * \return Standard. + * + * \sa osl_get_nth_row(), osl_rbtree_first_row(). + */ int osl_rbtree_last_row(const struct osl_table *t, unsigned col_num, struct osl_row **result); + +/** + * Get the row with n-th greatest value. + * + * \param t Pointer to an open osl table. + * \param col_num The column number. + * \param n The rank of the desired row. + * \param result Row is returned here. + * + * Retrieve the n-th order statistic with respect to the compare function + * of the rbtree column \a col_num. In other words, get the row with + * \a n th greatest value in column \a col_num. It is an error if + * \a col_num is not a rbtree column, or if \a n is larger than the + * number of rows in the table. + * + * \return Standard. + * + * \sa osl_storage_flags, osl_compare_func, osl_get_row(), + * osl_rbtree_last_row(), osl_rbtree_first_row(), osl_get_rank(). + */ int osl_get_nth_row(const struct osl_table *t, unsigned col_num, unsigned n, struct osl_row **result); + +/** + * Get the rank of a row. + * + * \param t An open osl table. + * \param r The row to get the rank of. + * \param col_num The number of an rbtree column. + * \param rank Result pointer. + * + * The rank is, by definition, the position of the row in the linear order + * determined by an in-order tree walk of the rbtree associated with column + * number \a col_num of \a table. + * + * \return Standard. + * + * \sa osl_get_nth_row(). + */ int osl_get_rank(const struct osl_table *t, struct osl_row *r, unsigned col_num, unsigned *rank); + +/** + * Get a string describing the error code passed in the argument. + * + * \param num The error code. + * + * This works just like strerror(3). The given number must be an osl error + * code. The result must not be freed by the caller. + * + * \return The error text corresponding to an osl error code. + */ +const char *osl_strerror(int num); + +#pragma GCC visibility pop