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raw | patch | inline | side by side (parent: 1c006c7)
author | oetiker <oetiker@a5681a0c-68f1-0310-ab6d-d61299d08faa> | |
Mon, 28 Sep 2009 16:21:13 +0000 (16:21 +0000) | ||
committer | oetiker <oetiker@a5681a0c-68f1-0310-ab6d-d61299d08faa> | |
Mon, 28 Sep 2009 16:21:13 +0000 (16:21 +0000) |
program/doc/librrd.pod | patch | blob | history |
diff --git a/program/doc/librrd.pod b/program/doc/librrd.pod
index 4daa93cf73c74bc5533564b60ca8073175e2c1aa..038746c47a3220a38f6a5cd7f18aa038f74e9412 100644 (file)
--- a/program/doc/librrd.pod
+++ b/program/doc/librrd.pod
incomplete as long as this warning persists. For more information about
the B<librrd> functions, always consult the source code.
+=head1 CORE FUNCTIONS
+
+=over 4
+
+=item B<rrd_dump_cb_r(char *filename, int opt_header, rrd_output_callback_t cb, void *user)>
+
+In some situations it is necessary to get the output of C<rrd_dump> without
+writing it to a file or the standard output. In such cases an application
+can ask B<rrd_dump_cb_r> to call an user-defined function each time there
+is output to be stored somewhere. This can be used, to e.g. directly feed
+an XML parser with the dumped output or transfer the resulting string
+in memory.
+
+The arguments for B<rrd_dump_cb_r> are the same as for B<rrd_dump_opt_r>
+except that the output filename parameter is replaced by the user-defined
+callback function and an additional parameter for the callback function
+that is passed untouched, i.e. to store information about the callback state
+needed for the user-defined callback to function properly.
+
+Recent versions of B<rrd_dump_opt_r> internally use this callback mechanism
+to write their output to the file provided by the user.
+
+ size_t rrd_dump_opt_cb_fileout(
+ const void *data,
+ size_t len,
+ void *user)
+ {
+ return fwrite(data, 1, len, (FILE *)user);
+ }
+
+The associated call for B<rrd_dump_cb_r> looks like
+
+ res = rrd_dump_cb_r(filename, opt_header,
+ rrd_dump_opt_cb_fileout, (void *)out_file);
+
+where the last parameter specifies the file handle B<rrd_dump_opt_cb_fileout>
+should write to. There's no specific condition for the callback to detect
+when it is called for the first time, nor for the last time. If you require
+this for initialization and cleanup you should do those tasks before and
+after calling B<rrd_dump_cr_r> respectively.
+
+=back
+
=head1 UTILITY FUNCTIONS
-=over
+=over 4
=item B<rrd_random()>
In contrast to L<mkdir(2)>, the function does B<not> fail if C<pathname>
already exists and is a directory.
-=item B<rrd_dump_cr_r(char *filename, int opt_header, rrd_output_callback_t cb, void *user)>
-
-In some situations it is necessary to get the output of C<rrd_dump> without
-writing it to a file or the standard output. In such cases an application
-can ask B<rrd_dump_cb_r> to call an user-defined function each time there
-is output to be stored somewhere. This can be used, to e.g. directly feed
-an XML parser with the dumped output or transfer the resulting string
-in memory.
-
-The arguments for B<rrd_dump_cb_r> are the same as for B<rrd_dump_opt_r>
-except that the output filename parameter is replaced by the user-defined
-callback function and an additional parameter for the callback function
-that is passed untouched, i.e. to store information about the callback state
-needed for the user-defined callback to function properly.
-
-Recent versions of B<rrd_dump_opt_r> internally use this callback mechanism
-to write their output to the file provided by the user.
-
- size_t rrd_dump_opt_cb_fileout(
- const void *data,
- size_t len,
- void *user)
- {
- return fwrite(data, 1, len, (FILE *)user);
- }
-
-The associated call for B<rrd_dump_cb_r> looks like
-
- res = rrd_dump_cb_r(filename, opt_header,
- rrd_dump_opt_cb_fileout, (void *)out_file);
-
-where the last parameter specifies the file handle B<rrd_dump_opt_cb_fileout>
-should write to. There's no specific condition for the callback to detect
-when it is called for the first time, nor for the last time. If you require
-this for initialization and cleanup you should do those tasks before and
-after calling B<rrd_dump_cr_r> respectively.
-
=back