ScyllaDB Docs ScyllaDB CPP-Rust Driver Getting Started

Getting Started¶

Installation¶

Dependencies¶

Packages for the dependencies: libuv (1.x), OpenSSL can be installed from distribution’s repositories.

# Example: Ubuntu/Debian:
sudo apt update
sudo apt install -y libuv1 openssl libssl

# Example: Rocky/RedHat:
sudo dnf install -y libuv openssl

The driver can also be built from source, in which case dependencies need to be installed in -dev or -devel versions.

Driver¶

Packages are available for some platforms - see the Installation section for a list.

They are available for download from the Releases section.

NOTE: If you have Datastax or ScyllaDB C/C++ Driver installed, you need to remove it first:

# Ubuntu/Debian:
sudo apt remove cassandra-cpp-driver
sudo apt remove scylla-cpp-driver


# Rocky/RedHat:
sudo dnf remove cassandra-cpp-driver
sudo dnf remove scylla-cpp-driver

# Example: Ubuntu/Debian:
wget https://github.com/scylladb/cpp-rust-driver/releases/download/<LATEST_VERSION>/libscylla-cpp-driver-dev_<LATEST_VERSION>.deb
sudo apt update
sudo apt install -y ./libscylla-cpp-driver-dev_<LATEST_VERSION>.deb


# Example: Rocky/RedHat:
wget https://github.com/scylladb/cpp-rust-driver/releases/download/<LATEST_VERSION>/scylla-cpp-rust-driver-<LATEST_VERSION>.rpm https://github.com/scylladb/cpp-rust-driver/releases/download/<LATEST_VERSION>/scylla-cpp-rust-driver-devel-<LATEST_VERSION>.rpm
sudo dnf install -y ./scylla-cpp-rust-driver-<LATEST_VERSION>.rpm ./scylla-cpp-rust-driver-devel-<LATEST_VERSION>.rpm

Connecting¶

#include <cassandra.h>
#include <stdio.h>

int main() {
  /* Setup and connect to cluster */
  CassFuture* connect_future = NULL;
  CassCluster* cluster = cass_cluster_new();
  CassSession* session = cass_session_new();

  /* Add contact points */
  cass_cluster_set_contact_points(cluster, "127.0.0.1");

  /* Shard-awareness (ScyllaDB only): choose the local (ephemeral) port range */
  cass_cluster_set_local_port_range(cluster, 49152, 65535);

  /* Provide the cluster object as configuration to connect the session */
  connect_future = cass_session_connect(session, cluster);

  /* This operation will block until the result is ready */
  CassError rc = cass_future_error_code(connect_future);

  if (rc != CASS_OK) {
    /* Display connection error message */
    const char* message;
    size_t message_length;
    cass_future_error_message(connect_future, &message, &message_length);
    fprintf(stderr, "Connect error: '%.*s'\n", (int)message_length, message);
  }

  /* Run queries... */

  cass_future_free(connect_future);
  cass_session_free(session);
  cass_cluster_free(cluster);

  return 0;
}

To connect a session, a CassCluster object will need to be created and configured. The minimal configuration needed to connect is a list of contact points. The contact points are used to initialize the driver and it will automatically discover the rest of the nodes in your cluster.

Perfomance Tip: Include more than one contact point to be robust against node failures.

Futures¶

The driver is designed so that no operation will force an application to block. Operations that would normally cause the application to block, such as connecting to a cluster or running a query, instead return a CassFuture object that can be waited on, polled, or used to register a callback.

NOTE: The API can also be used synchronously by waiting on or immediately attempting to get the result from a future.

Executing Queries¶

Queries are executed using CassStatement objects. Statements encapsulate the query string and the query parameters.

void execute_query(CassSession* session) {
  /* Create a statement with zero parameters */
  CassStatement* statement
    = cass_statement_new("INSERT INTO example (key, value) VALUES ('abc', 123)", 0);

  CassFuture* query_future = cass_session_execute(session, statement);

  /* Statement objects can be freed immediately after being executed */
  cass_statement_free(statement);

  /* This will block until the query has finished */
  CassError rc = cass_future_error_code(query_future);

  printf("Query result: %s\n", cass_error_desc(rc));

  cass_future_free(query_future);
}

Parameterized Queries (Positional)¶

Parameterized queries allow the same query string to be executed multiple times with different values, avoiding string manipulation in your application.

Perfomance Tip: If the same query is being reused multiple times, prepared statements should be used to optimize performance.

void execute_parametrized_query(CassSession* session) {
  /* There are two bind variables in the query string */
  CassStatement* statement
    = cass_statement_new("INSERT INTO example (key, value) VALUES (?, ?)", 2);

  /* Bind the values using the indices of the bind variables */
  cass_statement_bind_string(statement, 0, "abc");
  cass_statement_bind_int32(statement, 1, 123);

  CassFuture* query_future = cass_session_execute(session, statement);

  /* Statement objects can be freed immediately after being executed */
  cass_statement_free(statement);

  /* This will block until the query has finished */
  CassError rc = cass_future_error_code(query_future);

  printf("Query result: %s\n", cass_error_desc(rc));

  cass_future_free(query_future);
}

Handling Query Results¶

A single row can be retrieved using the convenience function cass_result_first_row() to get the first row. A CassIterator object may also be used to iterate over the returned row(s).

void handle_query_result(CassFuture* future) {
  /* This will also block until the query returns */
  const CassResult* result = cass_future_get_result(future);

  /* If there was an error then the result won't be available */
  if (result == NULL) {

    /* Handle error */

    cass_future_free(future);
    return;
  }

  /* The future can be freed immediately after getting the result object */
  cass_future_free(future);

  /* This can be used to retrieve the first row of the result */
  const CassRow* row = cass_result_first_row(result);

  /* Now we can retrieve the column values from the row */
  const char* key;
  size_t key_length;
  /* Get the column value of "key" by name */
  cass_value_get_string(cass_row_get_column_by_name(row, "key"), &key, &key_length);

  cass_int32_t value;
  /* Get the column value of "value" by name */
  cass_value_get_int32(cass_row_get_column_by_name(row, "value"), &value);


  /* This will free the result as well as the string pointed to by 'key' */
  cass_result_free(result);
}

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