mongoc_client_t¶

A single-threaded MongoDB connection. See Connection Pooling.

Synopsis¶

typedef struct _mongoc_client_t mongoc_client_t; typedef mongoc_stream_t *(*mongoc_stream_initiator_t) (  const mongoc_uri_t *uri,  const mongoc_host_list_t *host,  void *user_data,  bson_error_t *error); 

mongoc_client_t is an opaque type that provides access to a MongoDB server, replica set, or sharded cluster. It maintains management of underlying sockets and routing to individual nodes based on mongoc_read_prefs_t or mongoc_write_concern_t.

Streams¶

The underlying transport for a given client can be customized, wrapped or replaced by any implementation that fulfills mongoc_stream_t. A custom transport can be set with mongoc_client_set_stream_initiator().

Thread Safety¶

mongoc_client_t is NOT thread-safe and should only be used from one thread at a time. When used in multi-threaded scenarios, it is recommended that you use the thread-safe mongoc_client_pool_t to retrieve a mongoc_client_t for your thread.

Fork Safety¶

A mongoc_client_t is only usable in the parent process after a fork. The child process must call mongoc_client_reset().

Example¶

example-client.c¶

/* gcc example-client.c -o example-client $(pkg-config --cflags --libs  * libmongoc-1.0) */ /* ./example-client [CONNECTION_STRING [COLLECTION_NAME]] */ #include <mongoc/mongoc.h> #include <stdio.h> #include <stdlib.h> int main (int argc, char *argv[]) {  mongoc_client_t *client;  mongoc_collection_t *collection;  mongoc_cursor_t *cursor;  bson_error_t error;  const bson_t *doc;  const char *collection_name = "test";  bson_t query;  char *str;  const char *uri_string = "mongodb://127.0.0.1/?appname=client-example";  mongoc_uri_t *uri;  mongoc_init ();  if (argc > 1) {  uri_string = argv[1];  }  if (argc > 2) {  collection_name = argv[2];  }  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;  }  client = mongoc_client_new_from_uri (uri);  if (!client) {  return EXIT_FAILURE;  }  mongoc_client_set_error_api (client, 2);  bson_init (&query);  collection = mongoc_client_get_collection (client, "test", collection_name);  cursor = mongoc_collection_find_with_opts (collection,  &query,  NULL, /* additional options */  NULL); /* read prefs, NULL for default */  while (mongoc_cursor_next (cursor, &doc)) {  str = bson_as_canonical_extended_json (doc, NULL);  fprintf (stdout, "%s\n", str);  bson_free (str);  }  if (mongoc_cursor_error (cursor, &error)) {  fprintf (stderr, "Cursor Failure: %s\n", error.message);  return EXIT_FAILURE;  }  bson_destroy (&query);  mongoc_cursor_destroy (cursor);  mongoc_collection_destroy (collection);  mongoc_uri_destroy (uri);  mongoc_client_destroy (client);  mongoc_cleanup ();  return EXIT_SUCCESS; } 