#include "cmdline.h"
#include "threads.h"

#include <iostream>

using namespace std;


#if defined(HAVE_THREADS)
// Define a concrete ConnectionPool derivative.  Takes connection
// parameters as inputs to its ctor, which it uses to create the
// connections we're called upon to make.  Note that we also declare
// a global pointer to an object of this type, which we create soon
// after startup; this should be a common usage pattern, as what use
// are multiple pools?
class SimpleConnectionPool : public mysqlpp::ConnectionPool
{
public:
    // The object's only constructor
    SimpleConnectionPool(mysqlpp::examples::CommandLine& cl) :
    conns_in_use_(0),
    db_(mysqlpp::examples::db_name),
    server_(cl.server()),
    user_(cl.user()),
    password_(cl.pass())
    {
    }

    // The destructor.  We _must_ call ConnectionPool::clear() here,
    // because our superclass can't do it for us.
    ~SimpleConnectionPool()
    {
        clear();
    }

    // Do a simple form of in-use connection limiting: wait to return
    // a connection until there are a reasonably low number in use
    // already.  Can't do this in create() because we're interested in
    // connections actually in use, not those created.  Also note that
    // we keep our own count; ConnectionPool::size() isn't the same!
    mysqlpp::Connection* grab()
    {
        while (conns_in_use_ > 8) {
            cout.put('R'); cout.flush(); // indicate waiting for release
            sleep(1);
        }

        ++conns_in_use_;
        return mysqlpp::ConnectionPool::grab();
    }

    // Other half of in-use conn count limit
    void release(const mysqlpp::Connection* pc)
    {
        mysqlpp::ConnectionPool::release(pc);
        --conns_in_use_;
    }

protected:
    // Superclass overrides
    mysqlpp::Connection* create()
    {
        // Create connection using the parameters we were passed upon
        // creation.  This could be something much more complex, but for
        // the purposes of the example, this suffices.
        cout.put('C'); cout.flush(); // indicate connection creation
        return new mysqlpp::Connection(
                db_.empty() ? 0 : db_.c_str(),
                server_.empty() ? 0 : server_.c_str(),
                user_.empty() ? 0 : user_.c_str(),
                password_.empty() ? "" : password_.c_str());
    }

    void destroy(mysqlpp::Connection* cp)
    {
        // Our superclass can't know how we created the Connection, so
        // it delegates destruction to us, to be safe.
        cout.put('D'); cout.flush(); // indicate connection destruction
        delete cp;
    }

    unsigned int max_idle_time()
    {
        // Set our idle time at an example-friendly 3 seconds.  A real
        // pool would return some fraction of the server's connection
        // idle timeout instead.
        return 3;
    }

private:
    // Number of connections currently in use
    unsigned int conns_in_use_;

    // Our connection parameters
    std::string db_, server_, user_, password_;
};
SimpleConnectionPool* poolptr = 0;


static thread_return_t CALLBACK_SPECIFIER
worker_thread(thread_arg_t running_flag)
{
    // Ask the underlying C API to allocate any per-thread resources it
    // needs, in case it hasn't happened already.  In this particular
    // program, it's almost guaranteed that the safe_grab() call below
    // will create a new connection the first time through, and thus
    // allocate these resources implicitly, but there's a nonzero chance
    // that this won't happen.  Anyway, this is an example program,
    // meant to show good style, so we take the high road and ensure the
    // resources are allocated before we do any queries.
    mysqlpp::Connection::thread_start();
    cout.put('S'); cout.flush(); // indicate thread started

    // Pull data from the sample table a bunch of times, releasing the
    // connection we use each time.
    for (size_t i = 0; i < 6; ++i) {
        // Go get a free connection from the pool, or create a new one
        // if there are no free conns yet.  Uses safe_grab() to get a
        // connection from the pool that will be automatically returned
        // to the pool when this loop iteration finishes.
        mysqlpp::ScopedConnection cp(*poolptr, true);
        if (!cp) {
            cerr << "Failed to get a connection from the pool!" << endl;
            break;
        }

        // Pull a copy of the sample stock table and print a dot for
        // each row in the result set.
        mysqlpp::Query query(cp->query("select * from stock"));
        mysqlpp::StoreQueryResult res = query.store();
        for (size_t j = 0; j < res.num_rows(); ++j) {
            cout.put('.');
        }

        // Delay 1-4 seconds before doing it again.  Because this can
        // delay longer than the idle timeout, we'll occasionally force
        // the creation of a new connection on the next loop.
        sleep(rand() % 4 + 1);  
    }

    // Tell main() that this thread is no longer running
    *reinterpret_cast<bool*>(running_flag) = false;
    cout.put('E'); cout.flush(); // indicate thread ended
    
    // Release the per-thread resources before we exit
    mysqlpp::Connection::thread_end();

    return 0;
}
#endif


int
main(int argc, char *argv[])
{
#if defined(HAVE_THREADS)
    // Get database access parameters from command line
    mysqlpp::examples::CommandLine cmdline(argc, argv);
    if (!cmdline) {
        return 1;
    }

    // Create the pool and grab a connection.  We do it partly to test
    // that the parameters are good before we start doing real work, and
    // partly because we need a Connection object to call thread_aware()
    // on to check that it's okay to start doing that real work.  This
    // latter check should never fail on Windows, but will fail on most
    // other systems unless you take positive steps to build with thread
    // awareness turned on.  See README-*.txt for your platform.
    poolptr = new SimpleConnectionPool(cmdline);
    try {
        mysqlpp::ScopedConnection cp(*poolptr, true);
        if (!cp->thread_aware()) {
            cerr << "MySQL++ wasn't built with thread awareness!  " <<
                    argv[0] << " can't run without it." << endl;
            return 1;
        }
    }
    catch (mysqlpp::Exception& e) {
        cerr << "Failed to set up initial pooled connection: " <<
                e.what() << endl;
        return 1;
    }

    // Setup complete.  Now let's spin some threads...
    cout << endl << "Pool created and working correctly.  Now to do "
            "some real work..." << endl;
    srand((unsigned int)time(0));
    bool running[] = {
            true, true, true, true, true, true, true,
            true, true, true, true, true, true, true };
    const size_t num_threads = sizeof(running) / sizeof(running[0]);
    size_t i;
    for (i = 0; i < num_threads; ++i) {
        if (int err = create_thread(worker_thread, running + i)) {
            cerr << "Failed to create thread " << i <<
                    ": error code " << err << endl;
            return 1;
        }
    }

    // Test the 'running' flags every second until we find that they're
    // all turned off, indicating that all threads are stopped.
    cout.put('W'); cout.flush(); // indicate waiting for completion
    do {
        sleep(1);
        i = 0;
        while (i < num_threads && !running[i]) ++i;
    }
    while (i < num_threads);
    cout << endl << "All threads stopped!" << endl;

    // Shut it all down...
    delete poolptr;
    cout << endl;
#else
    (void)argc;     // warning squisher
    cout << argv[0] << " requires that threads be enabled!" << endl;
#endif

    return 0;
}