assert failure in read_buffer.hpp at line 90 #380
Comments
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just a bit of more information, the query in our case returns empty results. |
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I am using mariadb server on linux. |
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If the failure only happens sometimes, you may be violating this precondition. Remember that a single connection shouldn't be used to initiate any async operation until the one it's currently executing completes. To validate this hypothesis, you can add a flag that gets set when an operation starts and cleared when it finishes. If this is the case, you may need to introduce synchronization, maybe using a channel. Let me know if you need help with this. Let me know if it helps. Regards, |
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okay let me verify and get back, thanks for the reply. |
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Thanks again for the insights, indeed the parallel execution was the case, do you have any sample code on this channel stuff ? |
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This has come up before, so I hope I can implement #367 for Boost 1.88. You need an object that provides asynchronous mutual exclusion (an async mutex, if you prefer). With ideas taken from the first 2 examples in this Asio page: asio::awaitable<void> coro_main(
mysql::tcp_connection& conn,
asio::experimental::channel<void()>& lock
)
{
// Claim the lock by sending a message to the channel. Since the
// channel signature is void(), there are no arguments to send in the
// message itself.
co_await lock.async_send();
// Issue the SQL query to the server
const char* sql = "SELECT 'Hello world!'";
mysql::results result;
co_await conn.async_execute(sql, result);
// Release the lock by receiving the message back again.
lock.try_receive([](auto...) {});
}The channel must be created like this: asio::experimental::channel<void()> lock(ctx, 1); // ctx is your io_contextThe idea is that you create a channel with a buffer size of 1 element. If the lock is free, the channel's buffer will be empty and Some notes:
Another option is using Boost.MySQL Regards, |
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To make the code clean and easily understandable, I would go with the connection pool. please point me to the patches if any so that i could apply them on my local tree and get the feature. Hope, things are stable and robust. |
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I'd recommend using the Boost 1.87 beta: https://archives.boost.io/beta/1.87.0.beta1/source/boost_1_87_0_b1_rc2.tar.gz This is how I'd use the pool: // In main
// Pool configuration
mysql::pool_params params {
.server_address = mysql::host_and_port("your-hostname"),
.username = "your-username",
.password = "your-password",
.database = "your-database",
.max_size = 1, // Set to the max number of connections you want. You probably want more than 1
};
// Create the pool
mysql::connection_pool pool (ctx, std::move(params));
// Run it. Only needed once per pool
pool.async_run(asio::detached);
// Call pool.cancel() to make run exit when your program
// needs to quit, e.g. from a signal handler
asio::awaitable<void> coro_main(
mysql::connection_pool& pool
)
{
// Get a connection. This is a proxy to an any_connection.
// If all connections are in use, this will wait until one is free.
// By default, this waits forever, so it may be adequate to set a timeout
// (maybe to the entire coroutine) using asio::cancel_after
mysql::pooled_connection conn = co_await pool.async_get_connection();
// Use it normally
mysql::results result;
co_await conn->async_execute("SELECT...", result);
// conn's destructor returns it to the pool
}Hope it helps. |
I am using boost 1.86 and seeing a random assert failure at times. the same query works fine but asserts at times. wondering what is the cause for below assert failure,
/work/opensource//base/boost_1_86_0/boost/mysql/impl/internal/sansio/read_buffer.hpp:90: void boost::mysql::detail::read_buffer::move_to_pending(std::size_t): Assertion `length <= free_size()' failed.
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