AsyncDistributedSqlEngine:waitMany

Wait on worker processes and return the vector of query results.

Prototype

 
    Vector<Table> *waitMany();
 

Arguments

void	No arguments

Description

This method waits on the worker processes and returns a vector containing the results of each query launched by executeMany().

Returns

A vector containing the results of each query launched by executeMany().

Example

The following snippet defines a vector of query strings and 9 arguments to be substituted into the queries; then calls executeMany() to process these queries in parallel. The query results are then returned by waitMany() and the first result is printed out:

     
    const size_t nWorkers = 4;
    const char *nodes[] = 
    {
        "localhost:5001",
        "localhost:5002"
    };
     
    int main(int argc, char** argv)
    {
        try {

            McoSql::Allocator my_allocator;
             
            McoSql::AsyncDistributedSqlEngine engine(nWorkers);            
            if (!engine.open(nodes, sizeof(nodes) / sizeof(nodes[0]))) 
            {
                printf("Open failed: %s\n", engine.getError()->cstr());
                return 1;
            }
            ...
            McoSql::Vector<McoSql::String> *queries = 
                McoSql::Vector<McoSql::String>::create(&my_allocator, nWorkers);
 
            for (size_t i = 0; i < nWorkers; i++) 
            {
                queries->items[i] = McoSql::String::create( &my_allocator,
                    "INSERT INTO MyTable(pk, value, u2, i1, i2, i4, i8, flt, dbl) 
                    VALUES (%v, %v, %v, %v, %v, %v, %v, %v, %v)");
            }
 
            McoSql::Vector<McoSql::ConnectionArgs> *args = 
                McoSql::Vector<McoSql::ConnectionArgs>::create(&my_allocator, nWorkers);
            for (size_t i = 0; i < nWorkers; i++) 
            {
                McoSql::ConnectionArgs *ca = new McoSql::ConnectionArgs(&my_allocator, 9 /*nParams*/);
                ca->args[0] = McoSql::IntValue::create(&my_allocator, i*100);
                ca->args[1] = McoSql::String::format(&my_allocator, "str%d", i);
                ca->args[2] = McoSql::IntValue::create(&my_allocator, i);
                ca->args[3] = McoSql::IntValue::create(&my_allocator, i);
                ca->args[4] = McoSql::IntValue::create(&my_allocator, i);
                ca->args[5] = McoSql::IntValue::create(&my_allocator, i);
                ca->args[6] = McoSql::IntValue::create(&my_allocator, i);
                ca->args[7] = McoSql::RealValue::create(&my_allocator, i*100);
                ca->args[8] = McoSql::RealValue::create(&my_allocator, i*100);
                args->items[i] = ca;
            }
            McoSql::Allocator ret_allocator;
             
            engine.executeMany(queries, args, &ret_allocator);
 
            McoSql::Vector< McoSql::Table> *vret = engine.waitMany();
             
            McoSql::Table *sret = vret->at(0);
            printf (" Single query Fields are:\n");
            for (size_t fno = 0; fno < sret->fields()->length; fno++) 
            {
                printf ("      %s - %d\n", sret->fields()->at(fno)->name()->cstr(), 
                        sret->fields()->at(fno)->type());
            }
            printf ("\n");
        }
    }