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Revision 1.5 by root, Thu Oct 11 03:21:49 2012 UTC vs.
Revision 1.6 by root, Mon Mar 4 11:40:52 2019 UTC

1NAME 1NAME
2 Coro::Mysql - let other threads run while doing mysql requests 2 Coro::Mysql - let other threads run while doing mysql/mariadb requests
3 3
4SYNOPSIS 4SYNOPSIS
5 use Coro::Mysql; 5 use Coro::Mysql;
6 6
7 my $DBH = Coro::Mysql::unblock DBI->connect (...); 7 my $DBH = Coro::Mysql::unblock DBI->connect (...);
8 8
9DESCRIPTION 9DESCRIPTION
10 (Note that in this manual, "thread" refers to real threads as 10 (Note that in this manual, "thread" refers to real threads as
11 implemented by the Coro module, not to the built-in windows process 11 implemented by the Coro module, not to the built-in windows process
12 emulation which unfortunately is also called "threads") 12 emulation which unfortunately is also called "threads").
13 13
14 This module replaces the I/O handlers for a database connection, with 14 This module replaces the I/O handlers for a database connection, with
15 the effect that "patched" database handles no longer block the all 15 the effect that "patched" database handles no longer block all threads
16 threads of a process, but only the thread that does the request. 16 of a process, but only the thread that does the request. It should work
17 for both DBD::mysql and DBD::MariaDB connections and a wide range of
18 mariadb/mysql client libraries.
17 19
18 This can be used to make parallel sql requests using Coro, or to do 20 This can be used to make parallel sql requests using Coro, or to do
19 other stuff while mysql is rumbling in the background. 21 other stuff while mariadb is rumbling in the background.
20 22
21 CAVEAT 23 CAVEAT
22 Note that this module must be linked against exactly the same (shared, 24 Note that this module must be linked against exactly the same (shared,
23 possibly not working with all OSes) libmysqlclient library as 25 possibly not working with all OSes) libmariadb/libmysqlclient library as
24 DBD::mysql, otherwise it will not work. 26 DBD::MariaDB/DBD::mysql, otherwise it will not work.
25
26 Also, this module requires a header file that apparently isn't installed
27 everywhere (violite.h), and therefore comes with it's own copy, which
28 might or might not be compatible to the violite.h of your library - when
29 in doubt, make sure all the libmysqlclient header files are installed
30 and delete the violite.h header that comes with this module.
31
32 On the good side, this module does a multitude of checks to ensure that
33 the libray versions match on the binary level, so on incompatibilities
34 you should expect an exception when trying to unblock a handle, rather
35 than data corruption.
36 27
37 Also, while this module makes database handles non-blocking, you still 28 Also, while this module makes database handles non-blocking, you still
38 cannot run multiple requests in parallel on the same database handle. If 29 cannot run multiple requests in parallel on the same database handle. If
39 you want to run multiple queries in parallel, you have to create 30 you want to run multiple queries in parallel, you have to create
40 multiple database connections, one for each thread that runs queries. 31 multiple database connections, one for each thread that runs queries.
… …
72 handle unusable. As far as Coro::Mysql is concerned, the handle can be 63 handle unusable. As far as Coro::Mysql is concerned, the handle can be
73 safely destroyed, but it's not clear how mysql itself will react to a 64 safely destroyed, but it's not clear how mysql itself will react to a
74 cancellation. 65 cancellation.
75 66
76FUNCTIONS 67FUNCTIONS
77 Coro::Mysql offers a single user-accessible function: 68 Coro::Mysql offers these functions, the only one that oyu usually need
69 is "unblock":
78 70
79 $DBH = Coro::Mysql::unblock $DBH 71 $DBH = Coro::Mysql::unblock $DBH
80 This function takes a DBI database handles and "patches" it so it 72 This function takes a DBI database handles and "patches" it so it
81 becomes compatible to Coro threads. 73 becomes compatible to Coro threads.
82 74
… …
91 It is also safe to pass "undef", so code like this is works as 83 It is also safe to pass "undef", so code like this is works as
92 expected: 84 expected:
93 85
94 my $dbh = DBI->connect ($database, $user, $pass)->Coro::Mysql::unblock 86 my $dbh = DBI->connect ($database, $user, $pass)->Coro::Mysql::unblock
95 or die $DBI::errstr; 87 or die $DBI::errstr;
88
89 $bool = Coro::Mysql::is_unblocked $DBH
90 Returns true iff the database handle was successfully patched for
91 non-blocking operations.
92
93 $bool = Coro::Mysql::have_ev
94 Returns true if this Coro::Mysql installation is compiled with
95 special support for EV or not.
96
97 Even if compiled in, it will only be used if EV is actually the
98 AnyEvent event backend.
96 99
97USAGE EXAMPLE 100USAGE EXAMPLE
98 This example uses PApp::SQL and Coro::on_enter to implement a function 101 This example uses PApp::SQL and Coro::on_enter to implement a function
99 "with_db", that connects to a database, uses "unblock" on the resulting 102 "with_db", that connects to a database, uses "unblock" on the resulting
100 handle and then makes sure that $PApp::SQL::DBH is set to the 103 handle and then makes sure that $PApp::SQL::DBH is set to the
… …
145HISTORY 148HISTORY
146 This module was initially hacked together within a few hours on a long 149 This module was initially hacked together within a few hours on a long
147 flight to Malaysia, and seems to have worked ever since, with minor 150 flight to Malaysia, and seems to have worked ever since, with minor
148 adjustments for newer libmysqlclient libraries. 151 adjustments for newer libmysqlclient libraries.
149 152
153 Well, at least until mariadb introduced the new Pluggable Virtual IO API
154 in mariadb 10.3, which changed and broke everything. On the positive
155 side, the old system was horrible to use, as many GNU/Linux
156 distributions forgot to include the required heaqder files and there
157 were frequent small changes, while the new PVIO system seems to be
158 "official" and hopefully better supported.
159
150AUTHOR 160AUTHOR
151 Marc Lehmann <schmorp@schmorp.de> 161 Marc Lehmann <schmorp@schmorp.de>
152 http://home.schmorp.de/ 162 http://home.schmorp.de/
153 163

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