2 * Copyright (C) 2006-2010 Andre Noll <maan@systemlinux.org>
4 * Licensed under the GPL v2. For licencing details see COPYING.
7 /** \file write.h Writer-related structures. */
9 /** The list of supported writers. */
10 enum writer_enum {WRITER_ENUM};
13 * Describes one running instance of a writer.
16 /** The number of this writer. */
18 /** Writer-specific data. */
20 /** The writer-specific configuration of this node. */
22 struct btr_node *btrn;
27 /** Describes one supported writer. */
30 * The init function of the writer.
32 * It must fill in all other function pointers of the given
35 void (*init)(struct writer *w);
37 * The command line parser of the writer.
39 * It should check whether the command line options given by \a options
40 * are valid and return a pointer to the writer-specific configuration
41 * data determined by \a options. This function must either succeed or
42 * call exit(). Note that parse_config_or_die() might be called more
43 * than once with different values of \a options. \sa \ref
46 void *(*parse_config_or_die)(const char *options);
48 * Dellocate all configuration resources.
50 * This should free whatever was allocated by \ref parse_config_or_die().
52 void (*free_config)(void *config);
54 * Open one instance of this writer.
56 * Perform any preparations needed to write the incoming stream.
57 * Usually this function just allocates its private data structure and
58 * stores a pointer to that structure in the ->private data of the
59 * given parameter. This function must either succeed or terminate the
62 void (*open)(struct writer_node *);
64 * Prepare the fd sets for select.
66 * This is called from scheduler. It may use the sched pointer to add
67 * any file descriptors or to decrease the select timeout.
69 void (*pre_select)(struct sched *s, struct task *t);
73 * Called from the post_select function of the writer node's task.
75 void (*post_select)(struct sched *s, struct task *t);
77 * Close one instance of the writer.
79 * This function is assumed to succeed.
81 void (*close)(struct writer_node *);
85 * This is a optional function pointer used for cleaning up.
87 void (*shutdown)(struct writer_node *);
89 btr_command_handler execute;
92 /** Loop over each supported writer. */
93 #define FOR_EACH_WRITER(i) for (i = 0; i < NUM_SUPPORTED_WRITERS; i++)
95 /** Declare the init functions of all supported writers. */
98 /** Array containing the name of each writer. */
99 extern const char *writer_names[];
101 /** The writer structure for each supported writer. */
102 extern struct writer writers[NUM_SUPPORTED_WRITERS];