来自mongoc (C)驱动程序的MongoDB Atlas连接间歇性失败，并显示'No suitable servers found'

Question

我正在使用MongoDB C驱动程序(1.9.2(连接到我的Atlas Cluster(使用AWS的M5(。 我的请求经常成功，但我大约一半的时间收到此错误。我在请求之间等待的时间越长，请求成功的频率就越高。

我总是能够创建一个mongoc_client_t，但是当请求失败时，删除，插入或读取操作会收到此错误;

2019-12-30 23：10：50：:d ropCollection((： mongoc_collection_drop(( 失败的代码(13053(：：未找到合适的服务器：serverSelectionTimeoutMS已过期：[无法从服务器接收长度标头，在"xxxxx-shard-00-01-xxxxx.mongodb.net:27017"上调用 ismaster] [无法从服务器接收长度标头，在"xxxxx-shard-00-00-xxxxx.mongodb.net:27017"上调用 ismaster]

这是我的(简化(代码; 我尝试使用客户端池，然后切换到">serverSelectionTryOnce=false" - 它们在超时后都出现错误。

#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <mongoc.h>
#include <bson.h>
#include <bcon.h>
#define ERROR -1
#define GOOD   0
typedef struct _MongoContext
{
mongoc_uri_t*           uri;
mongoc_client_t*        client;
mongoc_database_t*      database;
mongoc_collection_t*    collection;
bson_error_t            error;
char*                   uriStr;
} MongoContext;
static const char* DEFAULT_URI = "mongodb+srv://<user>:<psswd>@<host>.mongodb.net/test?retryWrites=true&w=majority&serverSelectionTryOnce=false";
int getMongoContext(MongoContext* mctx, const char* dbname, const char* collname)
{
bson_error_t  error;
mctx->uriStr = strdup(DEFAULT_URI);
mctx->uri = mongoc_uri_new_with_error(mctx->uriStr, &error);                               
if(!mctx->uri) {
fprintf(stderr, "getMongoContext(): Unable to parse URI(%s)n(%s)", mctx->uriStr, error.message);
return ERROR;
}
//    mongoc_client_pool_t *pool = mongoc_client_pool_new(mctx->uri);
//    mongoc_client_pool_set_appname(pool, "my-mongo");
//    mongoc_client_pool_set_error_api(pool, MONGOC_ERROR_API_VERSION_2);
//    mctx->client = mongoc_client_pool_pop(pool);
mctx->client = mongoc_client_new_from_uri(mctx->uri);                                      
if(!mctx->client) {
fprintf(stderr, "getMongoContext(): mongoc_client_new_from_uri() failed(%s)", error.message);
return ERROR;
}
mongoc_client_set_appname(mctx->client, "my-mongo");                                       
mctx->database   = mongoc_client_get_database(mctx->client, dbname);
if(mctx->database == NULL) {
fprintf(stderr, "getMongoContext(): invalid database(%s)", dbname);
return ERROR;
}
mctx->collection = mongoc_client_get_collection(mctx->client, dbname, collname);
if(mctx->collection == NULL) {
fprintf(stderr, "getMongoContext(): invalid collection(%s)", collname);
}
char* ptr = strchr(mctx->uriStr, '@');
fprintf(stderr, "getMongoContext(): connection made for host(%s), db(%s), collection(%s)n", (ptr+1), dbname, collname);
return GOOD;
}
void closeMongoContext(MongoContext* mctx)
{
mongoc_collection_destroy(mctx->collection);
mongoc_database_destroy(mctx->database);
mongoc_uri_destroy(mctx->uri);
mongoc_client_destroy(mctx->client);
mongoc_cleanup();
free(mctx->uriStr);
}
/**
* read the collection in the given MongoContext
*/
int readCollection(MongoContext* mctx)
{
mongoc_cursor_t*    cursor;
const bson_t*       doc;
char*               str;
bson_t* query = bson_new();
cursor = mongoc_collection_find_with_opts(mctx->collection, query, NULL, NULL);
if(cursor == NULL) {
fprintf(stderr, "readCollection(): Unable to retrieve a cursor for collection(%s)",
mongoc_collection_get_name(mctx->collection));
return ERROR;
}
while(mongoc_cursor_next(cursor, &doc)) {
str = bson_as_canonical_extended_json(doc, NULL);
printf("%sn", str);
bson_free(str);
}
bson_destroy(query);
mongoc_cursor_destroy(cursor);
return GOOD;
}
int insertIntoCollection(MongoContext* mctx, const char* jsondata)
{
bson_t* doc;
bson_t  reply;
bson_error_t error;
doc = bson_new_from_json((const uint8_t*)jsondata, -1, &error);
if(!doc) {
fprintf(stderr, "insertIntoCollection(): bson_new_from_json() failed (%s)n", error.message);
return ERROR;
}
fprintf(stderr, "insertIntoCollection(): insert into collection(%s)n", mongoc_collection_get_name(mctx->collection));
bool b = mongoc_collection_insert_one(mctx->collection, doc, NULL, &reply, &error);
if(!b) {
fprintf(stderr, "insertIntoCollection(): mongoc_collection_insert_one() failed (%s)n", error.message);
}
bson_destroy(doc);
return GOOD;
}
int dropCollection(MongoContext* mctx)
{
bson_error_t error;
bool rval = mongoc_collection_drop(mctx->collection, &error);                              
if(!rval) {
fprintf(stderr, "dropCollection(): mongoc_collection_drop() failed code(%d)::%s", error.code, error.message);
fprintf(stderr, "dropCollection(): mongoc_collection_drop() failed on collection(%s) for(%s)",
mongoc_collection_get_name(mctx->collection), mctx->uriStr);
return (error.code == 26) ? GOOD : ERROR;                                               
}
return GOOD;
}
int main(int argc, char* argv[])
{
mongoc_init();
MongoContext mctx = {0};
getMongoContext(&mctx, "my-db", "my-collection");
if(dropCollection(&mctx) == ERROR) {
exit(1);
}
printf("collection dropped...n");
if(insertIntoCollection(&mctx, "{ "hello" : "world" }") == ERROR) {
exit(1);
}
printf("inserted into collection...n");
if(readCollection(&mctx) == ERROR) {
exit(1);
}
closeMongoContext(&mctx);
}

Answer 1

就我而言，这是一个版本问题。我必须升级我的 C 驱动程序版本以与服务器兼容。