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DatabaseCampaign: MySQL / concurrency fixes

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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
This commit is contained in:
Horst Schirmeier
2013-12-02 19:33:24 +01:00
parent 0907dfb0ae
commit 33b63651ae
4 changed files with 41 additions and 12 deletions
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23
src/core/util/DatabaseProtobufAdapter.cc
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@ -355,9 +355,11 @@ int DatabaseProtobufAdapter::TypeBridge_message::gatherTypes(StringJoiner &inser
void DatabaseProtobufAdapter::create_table(const Descriptor *toplevel_desc) {
assert (toplevel_desc != 0);
std::stringstream create_table_stmt, insert_stmt;
std::stringstream create_table_stmt;
StringJoiner insert_join, primary_join, question_marks;
insert_stmt.str("");
result_table_name = "result_" + toplevel_desc->name();
/* Fill our top level dummy type bridge with the fields from the
@ -376,14 +378,6 @@ void DatabaseProtobufAdapter::create_table(const Descriptor *toplevel_desc) {
// Create the Table
db->query(create_table_stmt.str().c_str());
// Prepare the insert statement
stmt = mysql_stmt_init(db->getHandle());
if (mysql_stmt_prepare(stmt, insert_stmt.str().c_str(), insert_stmt.str().length())) {
LOG << "query '" << insert_stmt.str() << "' failed: " << mysql_error(db->getHandle()) << std::endl;
exit(-1);
}
}
@ -414,6 +408,17 @@ int DatabaseProtobufAdapter::field_size_at_pos(const Message *msg, std::vector<i
bool DatabaseProtobufAdapter::insert_row(const google::protobuf::Message *msg) {
assert (msg->GetDescriptor() != 0 && msg->GetReflection() != 0);
if (!stmt) {
// Prepare the insert statement
// We didn't do that right in create_table() because we need to use the
// right DB connection for that (which may not have existed yet then).
stmt = mysql_stmt_init(db_insert->getHandle());
if (mysql_stmt_prepare(stmt, insert_stmt.str().c_str(), insert_stmt.str().length())) {
LOG << "query '" << insert_stmt.str() << "' failed: " << mysql_error(db_insert->getHandle()) << std::endl;
exit(-1);
}
}
MYSQL_BIND *bind = new MYSQL_BIND[top_level_msg.field_count];
/* We determine how many columns should be produced */