ViewVC Help
View File | Revision Log | Show Annotations | Download File
/cvs/Coro-Mysql/Mysql.pm
(Generate patch)

Comparing Coro-Mysql/Mysql.pm (file contents):
Revision 1.12 by root, Thu Jul 26 21:38:00 2012 UTC vs.
Revision 1.13 by root, Thu Oct 11 03:18:31 2012 UTC

… …
12 12
13(Note that in this manual, "thread" refers to real threads as implemented 13(Note that in this manual, "thread" refers to real threads as implemented
14by the Coro module, not to the built-in windows process emulation which 14by the Coro module, not to the built-in windows process emulation which
15unfortunately is also called "threads") 15unfortunately is also called "threads")
16 16
17This module "patches" DBD::mysql database handles so that they do not 17This module replaces the I/O handlers for a database connection, with the
18block the whole process, but only the thread that they are used in. 18effect that "patched" database handles no longer block the all threads of
19a process, but only the thread that does the request.
19 20
20This can be used to make parallel sql requests using Coro, or to do other 21This can be used to make parallel sql requests using Coro, or to do other
21stuff while mysql is rumbling in the background. 22stuff while mysql is rumbling in the background.
22 23
23=head2 CAVEAT 24=head2 CAVEAT
24 25
25Note that this module must be linked against exactly the same (shared, 26Note that this module must be linked against exactly the same (shared,
26possibly not working with all OSes) F<libmysqlclient> library as 27possibly not working with all OSes) F<libmysqlclient> library as
27DBD::mysql, otherwise it will not work. 28DBD::mysql, otherwise it will not work.
28 29
30Also, this module requires a header file that apparently isn't installed
31everywhere (F<violite.h>), and therefore comes with it's own copy, which
32might or might not be compatible to the F<violite.h> of your library -
33when in doubt, make sure all the libmysqlclient header files are installed
34and delete the F<violite.h> header that comes with this module.
35
36On the good side, this module does a multitude of checks to ensure that
37the libray versions match on the binary level, so on incompatibilities you
38should expect an exception when trying to unblock a handle, rather than
39data corruption.
40
29Also, while this module makes database handles non-blocking, you still 41Also, while this module makes database handles non-blocking, you still
30cannot run multiple requests in parallel on the same database handle. If 42cannot run multiple requests in parallel on the same database handle. If
31you want to run multiple queries in parallel, you have to create multiple 43you want to run multiple queries in parallel, you have to create multiple
32database connections, one for each thread that runs queries. Not doing so 44database connections, one for each thread that runs queries. Not doing
33can corrupt your data - use a Coro::Semaphore when in doubt. 45so can corrupt your data - use a Coro::Semaphore to protetc access to a
46shared database handle when in doubt.
34 47
35If you make sure that you never run two or more requests in parallel, you 48If you make sure that you never run two or more requests in parallel, you
36can freely share the database handles between threads, of course. 49can freely share the database handles between threads, of course.
37
38Also, this module uses a number of "unclean" techniques (patching an
39internal libmysql structure for one thing) and was initially hacked within
40a few hours on a long flight to Malaysia.
41
42It does, however, check whether it indeed got the structure layout
43correct, so you should expect perl exceptions or early crashes as opposed
44to data corruption when something goes wrong during patching.
45 50
46=head2 SPEED 51=head2 SPEED
47 52
48This module is implemented in XS, and as long as mysqld replies quickly 53This module is implemented in XS, and as long as mysqld replies quickly
49enough, it adds no overhead to the standard libmysql communication 54enough, it adds no overhead to the standard libmysql communication
… …
200 205
201=head1 SEE ALSO 206=head1 SEE ALSO
202 207
203L<Coro>, L<PApp::SQL> (a user friendly but efficient wrapper around DBI). 208L<Coro>, L<PApp::SQL> (a user friendly but efficient wrapper around DBI).
204 209
210=head1 HISTORY
211
212This module was initially hacked together within a few hours on a long
213flight to Malaysia, and seems to have worked ever since, with minor
214adjustments for newer libmysqlclient libraries.
215
205=head1 AUTHOR 216=head1 AUTHOR
206 217
207 Marc Lehmann <schmorp@schmorp.de> 218 Marc Lehmann <schmorp@schmorp.de>
208 http://home.schmorp.de/ 219 http://home.schmorp.de/
209 220

Diff Legend

– Removed lines
+ Added lines
< Changed lines
> Changed lines