According to
<http://dev.mysql.com/doc/refman/5.5/en/c-api-threaded-clients.html>,
a MySQL connection handle must not be used concurrently with an open
result set and mysql_use_result() in one thread
(DatabaseCampaign::run()), and mysql_query() in another
(DatabaseCampaign::collect_result_thread()). This indeed leads to
crashes when bounding the outgoing job queue (SERVER_OUT_QUEUE_SIZE),
and maybe even more insidous effects in other cases. The solution is
to create separate connections for both threads.
Additionally, call mysql_library_init() before spawning any threads.
Change-Id: I2981f2fdc67c9a2cbe8781f1a21654418f621aeb
The DatabaseCampaign interacts with the MySQL tables that are created
by the import-trace and prune-trace tools. It does offer all
unfinished experiment pilots from the database to the
fail-clients. Those clients send back a (by the experiment) defined
protobuf message as a result. The custom protobuf message does have to
need the form:
import "DatabaseCampaignMessage.proto";
message ExperimentMsg {
required DatabaseCampaignMessage fsppilot = 1;
repeated group Result = 2 {
// custom fields
required int32 bitoffset = 1;
optional int32 result = 2;
}
}
The DatabaseCampaignMessage is the pilot identifier from the
database. For each of the repeated result entries a row in a table is
allocated. The structure of this table is constructed (by protobuf
reflection) from the description of the message. Each field in the
Result group becomes a column in the result table. For the given
example it would be:
CREATE TABLE result_ExperimentMessage(
pilot_id INT,
bitoffset INT NOT NULL,
result INT,
PRIMARY_KEY(pilot_id)
)
Change-Id: I28fb5488e739d4098b823b42426c5760331027f8
