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MONGOC_CLIENT_POOL_T(3) libmongoc MONGOC_CLIENT_POOL_T(3)

A connection pool for multi-threaded programs. See Connection Pooling.

SYNOPSIS

typedef struct _mongoc_client_pool_t mongoc_client_pool_t


mongoc_client_pool_t is the basis for multi-threading in the MongoDB C driver. Since mongoc_client_t structures are not thread-safe, this structure is used to retrieve a new mongoc_client_t for a given thread. This structure is thread-safe, except for its destructor method, mongoc_client_pool_destroy(), which is not thread-safe and must only be called from one thread.

EXAMPLE

example-pool.c

/* gcc example-pool.c -o example-pool $(pkg-config --cflags --libs

* libmongoc-1.0) */ /* ./example-pool [CONNECTION_STRING] */ #include <mongoc/mongoc.h> #include <pthread.h> #include <stdio.h> static pthread_mutex_t mutex; static bool in_shutdown = false; static void * worker (void *data) {
mongoc_client_pool_t *pool = data;
mongoc_client_t *client;
bson_t ping = BSON_INITIALIZER;
bson_error_t error;
bool r;
BSON_APPEND_INT32 (&ping, "ping", 1);
while (true) {
client = mongoc_client_pool_pop (pool);
/* Do something with client. If you are writing an HTTP server, you
* probably only want to hold onto the client for the portion of the
* request performing database queries.
*/
r = mongoc_client_command_simple (
client, "admin", &ping, NULL, NULL, &error);
if (!r) {
fprintf (stderr, "%s\n", error.message);
}
mongoc_client_pool_push (pool, client);
pthread_mutex_lock (&mutex);
if (in_shutdown || !r) {
pthread_mutex_unlock (&mutex);
break;
}
pthread_mutex_unlock (&mutex);
}
bson_destroy (&ping);
return NULL; } int main (int argc, char *argv[]) {
const char *uri_string = "mongodb://127.0.0.1/?appname=pool-example";
mongoc_uri_t *uri;
bson_error_t error;
mongoc_client_pool_t *pool;
pthread_t threads[10];
unsigned i;
void *ret;
pthread_mutex_init (&mutex, NULL);
mongoc_init ();
if (argc > 1) {
uri_string = argv[1];
}
uri = mongoc_uri_new_with_error (uri_string, &error);
if (!uri) {
fprintf (stderr,
"failed to parse URI: %s\n"
"error message: %s\n",
uri_string,
error.message);
return EXIT_FAILURE;
}
pool = mongoc_client_pool_new (uri);
mongoc_client_pool_set_error_api (pool, 2);
for (i = 0; i < 10; i++) {
pthread_create (&threads[i], NULL, worker, pool);
}
sleep (10);
pthread_mutex_lock (&mutex);
in_shutdown = true;
pthread_mutex_unlock (&mutex);
for (i = 0; i < 10; i++) {
pthread_join (threads[i], &ret);
}
mongoc_client_pool_destroy (pool);
mongoc_uri_destroy (uri);
mongoc_cleanup ();
return EXIT_SUCCESS; }


AUTHOR

MongoDB, Inc

COPYRIGHT

2017-present, MongoDB, Inc

February 25, 2024 1.26.0