I am using dart powerSNMP for .Net.
I am trying to query a table using GetTable(), it does not work for me.
Below C# code does not return any row,
const string address = "xxx.xxx.xx.x";
using (var mgr = new Manager())
{
var slave = new ManagerSlave(mgr);
slave.Socket.ReceiveTimeout = 13000;
try
{
//Retrieve table using GetNext requests
Variable[,] table = slave.GetTable("1.3.6.1.4.1.14823.2.2.1.1.1.9",
SnmpVersion.Three,
null,
new Security()
{
AuthenticationPassword = "mypassword1",
AuthenticationProtocol = AuthenticationProtocol.Md5,
PrivacyPassword = "mypassword2",
PrivacyProtocol = PrivacyProtocol.Des
},
new IPEndPoint(IPAddress.Parse(address), 161),
0);
}catch(Exception ez)
{
}
}
This is supposed to return a set of records from given OID. but It does not return me anything. When I use MIB Browser, I see GetBulk operation fetches all the records for me.
But what is wrong with GetTable() here?
Related
I have a million records in my table. I want to call a soap service and i need to do process in all the records in less than one hour. and besides i should update my table , insert the requests and responses in my other tables. but the code below works on less than 10 records every time i run my app.
I know My code is wrong,, I want to know what is the best way to do it.
static async Task Send( )
{
var results = new ConcurrentDictionary<string, int>();
using (AppDbContext entities = new AppDbContext())
{
var List = entities.Request.Where(x => x.State == RequestState.InitialState).ToList();
Parallel.ForEach(Enumerable.Range(0, List.Count), async index =>
{
var selected = List.FirstOrDefault();
List.Remove( selected );
var res1 = await DoAsyncJob1(selected); ///await
// var res = CallService(selected);
var res2 = await DoAsyncJob2(selected); ///await
var res3 = await DoAsyncJob3(selected); ///await
// var responses = await Task.WhenAll(DoAsyncJob1, DoAsyncJob2, DoAsyncJob3);
// results.TryAdd(index.ToString(), res);
});
}
}
static async Task<int> DoAsyncJob1(Request item)
{
using (AppDbContext entities = new AppDbContext())
{
var bReq = new BankRequest();
bReq.Amount = Convert.ToDecimal(item.Amount);
bReq.CreatedAt = DateTime.Now;
bReq.DIBAN = item.DIBAN;
bReq.SIBAN = item.SIBAN;
entities.BankRequest.Add(bReq);
entities.SaveChanges();
}
return item.Id;
}
static async Task<int> DoAsyncJob2(Request item)
{
using (AppDbContext entities = new AppDbContext())
{
}
return item.Id;
}
static async Task<int> DoAsyncJob3(Request item)
{
using (AppDbContext entities = new AppDbContext())
{
}
return item.Id;
}
Maybe the below lines are wrong :
var selected = List.FirstOrDefault();
List.Remove( selected );
Thanks in advance..
First, it is a bad practice to use async-await within Parallel.For - you introduce only more load to the task scheduler and more overhead.
Second, you are right:
var selected = List.FirstOrDefault();
List.Remove( selected );
is very, very wrong. Your code will behave in a totally unpredictable way, due to the race conditions.
I am inserting 3000 plus data from my server to my SQLite Database. The problem is the inserting process is very slow. Is there a better way to insert the data efficiently and effectively? What I am doing is I converted the data I got from my server to JSON Object and insert it one-by-one. I know what I am doing is inefficient. How can I fix this?
public class AndroidSQLiteDb : ISQLiteDB
{
public SQLiteAsyncConnection GetConnection()
{
var dbFileName = "backend.db3";
var documentsPath = System.Environment.GetFolderPath(System.Environment.SpecialFolder.Personal);
var path = Path.Combine(documentsPath, dbFileName);
return new SQLiteAsyncConnection(path);
}
}
public async void FirstSyncContacts(string host, string database, string contact)
{
try
{
var db = DependencyService.Get<ISQLiteDB>();
var conn = db.GetConnection();
var sql = "SELECT * FROM tblContacts WHERE Coordinator = '" + contact + "'";
var getContacts = conn.QueryAsync<ContactsTable>(sql);
var resultCount = getContacts.Result.Count;
var current_datetime = DateTime.Now.ToString("yyyy-MM-dd hh:mm:00");
//Check if the retailer has been sync
if (resultCount < 1)
{
try
{
syncStatus.Text = "Syncing Retailer";
var link = Constants.requestUrl + "Host=" + host + "&Database=" + database + "&Contact=" + contact + "&Request=9DpndD";
string contentType = "application/json";
JObject json = new JObject
{
{ "ContactID", contact }
};
HttpClient client = new HttpClient();
var response = await client.PostAsync(link, new StringContent(json.ToString(), Encoding.UTF8, contentType));
if (response.IsSuccessStatusCode)
{
var content = await response.Content.ReadAsStringAsync();
if (content != "")
{
var contactsresult = JsonConvert.DeserializeObject<List<ContactsData>>(content);
foreach (var item in contactsresult)
{
// update only the properties that you have to...
item.LastSync = Convert.ToDateTime(current_datetime);
item.ServerUpdate = Convert.ToDateTime(item.ServerUpdate);
item.MobileUpdate = Convert.ToDateTime(item.MobileUpdate);
}
await conn.InsertAsync(contactsresult);
}
}
//Proceed to next function
FirstSyncRetailerGroup(host, database, contact);
}
catch (Exception ex)
{
Console.Write("Syncing Retailer Error " + ex.Message);
}
}
//If not get the retailer
else
{
SyncContacts(host, database, contact);
}
}
catch (Exception ex)
{
Console.Write("Syncing Retailer Error " + ex.Message);
}
}
Use the non-async Insert in one background thread, instead of 3000 separate async calls...
Re-use the List from your DeserializeObject step instead of creating new local objects that will just be thrown away on each loop iteration.
No need to assign all those json properties (item.XXX) to another local variable, just update the properties of each existing ContactsData as needed before inserting it into the DB.
Example using SQLiteConnection:
// Use the non-async version of SQLiteConnection
var conn = new SQLiteConnection(dbPath, true, null);
// code removed for example...
await System.Threading.Tasks.Task.Run(() =>
{
var contactsresult = JsonConvert.DeserializeObject<List<ContactsData>>(content);
// start a transaction block so all 3000 records are committed at once.
conn.BeginTransaction();
// Use `foreach` in order shortcut the need to retrieve the object from the list via its index
foreach (var item in contactsresult)
{
// update only the properties that you have to...
item.LastSync = Convert.ToDateTime(current_datetime);
item.ServerUpdate = Convert.ToDateTime(item.ServerUpdate);
item.MobileUpdate = Convert.ToDateTime(item.MobileUpdate);
conn.Insert(item);
}
conn.Commit();
});
Example using SQLiteAsyncConnection:
var db = DependencyService.Get<ISQLiteDB>();
var conn = db.GetConnection();
~~~
var contactsresult = JsonConvert.DeserializeObject<List<ContactsData>>(content);
foreach (var item in contactsresult)
{
// update only the properties that you have to...
item.LastSync = Convert.ToDateTime(current_datetime);
item.ServerUpdate = Convert.ToDateTime(item.ServerUpdate);
item.MobileUpdate = Convert.ToDateTime(item.MobileUpdate);
}
conn.InsertAsync(contactsresult); // Insert the entire list at once...
I had the same problem so even the answer is some years late, maybe can be usefull for somebody.
This is how I did.
First: I get the data all from server as json
var response = await client.GetAsync("your_server_url");
var content = await response.Content.ReadAsStringAsync();
ResponseData = JsonConvert.DeserializeObject<DataModel>(content);
Second: Save data to database
await conn.InsertAllAsync(ResponseData)
But in my case, because our app works offline data, I first insert all data in a temp table, then I get all new records comparing main table with temp table.
NewDataFromTemp = await conn.QueryAsync<DataModel>("SELECT * FROM [TableTemp] t WHERE t.[TABLE_ID] NOT IN (SELECT g.[TABLE_ID] FROM [MainTable] g)");
And insert new records in Main table
await conn.InsertAllAsync(NewDataFromTemp)
Then I check for updated records
UpdatedDataFromTemp = await conn.QueryAsync<DataModel>("SELECT t.* FROM [TableTemp] t, [MainTable] o WHERE t.[TABLE_ID]=o.[TABLE_ID] AND t.[TABLE_UPDATED]>o.[TABLE_UPDATED]");
And update all record in main table
await conn.UpdateAllAsync(UpdatedDataFromTemp);
I use logical delete so when updating the logical delete will be updated too.
I have a Document DB repository class that has one get method like below:
private static DocumentClient client;
public async Task<TEntity> Get(string id, string partitionKey = null)
{
try
{
RequestOptions requestOptions = null;
if (partitionKey != null)
{
requestOptions = new RequestOptions { PartitionKey = new PartitionKey(partitionKey) };
}
var result = await client.ReadDocumentAsync(
UriFactory.CreateDocumentUri(DatabaseId, CollectionId, id),
requestOptions);
return (TEntity)(dynamic)result.Resource;
}
catch (DocumentClientException e)
{
// Have logic for different exceptions actually
throw;
}
}
I have two collections - Collection1 and Collection2. Collection1 is non-partitioned whereas Collection2 is partitioned.
On the client side, I create two repository objects, one for each collection.
private static DocumentDBRepository<Collection1Item> collection1Repository = new DocumentDBRepository<Collection1Item>("Collection1");
private static DocumentDBRepository<Collection2Item> collection2Repository = new DocumentDBRepository<Collection2Item>("Collection2");
List<Collection1Item> collection1Items = await collection1Repository.GetItemsFromCollection1(); // Selects first forty documents based on time
List<UIItem> uiItems = new List<UIItem>();
foreach (var item in collection1Items)
{
var collection2Item = await storageRepository.Get(item.Collection2Reference, item.TargetId); // TargetId is my partition key for Collection2
uiItems.Add(new UIItem
{
ItemId = item.ItemId,
Collection1Reference = item.Id,
TargetId = item.TargetId,
Collection2Reference = item.Collection2Reference,
Value = collection2Item.Value
});
}
This works fine. But since it is happening sequentially with foreach, I wanted to do those Get calls in parallel. When I do it in parallel as below:
ConcurrentBag<UIItem> uiItems = new ConcurrentBag<UIItem>();
collection1Items.AsParallel().ForAll(async item => {
var collection2Item = await storageRepository.Get(item.Collection2Reference, item.TargetId); // TargetId is my partition key for Collection2
uiItems.Add(new UIItem
{
ItemId = item.ItemId,
Collection1Reference = item.Id,
TargetId = item.TargetId,
Collection2Reference = item.Collection2Reference,
Value = collection2Item.Value
});
}
);
It doesn't work and uiItems is always empty.
You don't need Parallel.For to run async operations concurrently. If they are truly asynchronous they already run concurrently.
You could collect the task returned from each operation and simply call await Task.WhenAll() on all the tasks. If you modify your lambda to create and return a UIItem, the result of await Task.WhenAll() will be a collection of UIItems. No need to modify global state from inside the concurrent operations.
For example:
var itemTasks = collection1Items.Select(async item =>
{
var collection2Item = await storageRepository.Get(item.Collection2Reference, item.TargetId);
return new UIItem
{
ItemId = item.ItemId,
Collection1Reference = item.Id,
TargetId = item.TargetId,
Collection2Reference = item.Collection2Reference,
Value = collection2Item.Value
}
});
var results= await Task.WhenAll(itemTasks);
A word of caution though - this will fire all Get operations concurrently. That may not be what you want, especially when calling a service with rate limiting.
Try simply starting tasks and waiting for all of them at the end. That would result in parallel execution.
var tasks = collection1Items.Select(async item =>
{
//var collection2Item = await storageRepository.Get...
return new UIItem
{
//...
};
});
var uiItems = await Task.WhenAll(tasks);
PLINQ is useful when working with in-memory constructs and using as many threads as possible, but if used with the async-await technique (which is for releasing threads while accessing external resources), you can end up with strange results.
I would like to share a solution for an issue i saw in some comments.
If you're scared about thread rate limit, and you want to limit this by yourself, you can do something like this, using SemaphoreSlim.
var nbCores = Environment.ProcessorCount;
var semaphore = new SemaphoreSlim(nbCores, nbCores);
var processTasks = items.Select(async x =>
{
await semaphore.WaitAsync();
try
{
await ProcessAsync();
}
finally
{
semaphore.Release();
}
});
await Task.WhenAll(processTasks);
In this example, i called concurrently my "ProcessAsync" but limited to {processor number} concurrent processes.
Hope that's help someone.
NB : You could set the "nbCores" variable as a proper value that satisfy your code condition, of course.
NB 2 : This example is for some use cases, not all of them. I would highly suggest with a big load of task to refer to TPL programming
I'm sort of having a hard time with this one. Well ok, I have two different solutions (solution1 has a WebApplication Project; solution2 has a Website Project). Inside the two solutions, there's a WCF service structure. I have the exact same code in both services (in their respective solutions). My code compiles just fine. From the service I do a simple call to a procedure that returns a cursor. When I execute the service from the WebApplication it works just fine; when I do the same from the Website I get error: "wrong number or types of arguments". They both call the same procedure, in the same DB. And I triple check my code, and is the same in both services. Any ideas or suggestions? My code is as follows in both solutions:
Service.cs
public List<A1001310> SearchClient_A1001310()
{
DataTable dataTable = new DataTable();
dataTable = DataManager.SearchClient();
List<A1001310> list = new List<A1001310>();
list = (from DataRow dr in dataTable.Rows
select new A1001310()
{
Id = Convert.ToInt32(dr["CLIENT_ID"]),
//ClientName = dr["NOM_CLIENTE"].ToString()
}).ToList();
return list;
}
DataManager.cs
public static DataTable SearchClient()
{
try
{
using (OleDbCommand cmd = new OleDbCommand(packetName + ".select_A1001310"))
{
cmd.CommandType = CommandType.StoredProcedure;
SqlManager sqlManager = new SqlManager();
return sqlManager.GetDataTable(cmd);
}
}
catch (Exception ex)
{
//TODO; Handle exception
}
return null;
}
The call to DataTable is:
public DataTable GetDataTable(OleDbCommand cmd)
{
using (DataSet ds = GetDataSet(cmd))
{
return ((ds != null && ds.Tables.Count > 0) ? ds.Tables[0] : null);
}
}
public DataSet GetDataSet(OleDbCommand cmd)
{
using (DataSet ds = new DataSet())
{
this.ConvertToNullBlankParameters(cmd);
using (OleDbConnection conn = new OleDbConnection(cmd.Connection == null ? _dbConnection : cmd.Connection.ConnectionString))
{
cmd.Connection = conn;
cmd.CommandTimeout = _connTimeout;
conn.Open();
//cmd.ExecuteScalar();
using (OleDbDataAdapter da = new OleDbDataAdapter(cmd))
da.Fill(ds);
}
return ds;
}
}
The procedure is as follow:
PROCEDURE select_A1001310(io_cursor OUT lcursor_data)
AS
BEGIN
OPEN io_cursor FOR
--
SELECT client_id
FROM a1001310
WHERE status = 'A'
--
EXCEPTION
WHEN OTHERS THEN
IF io_cursor%ISOPEN THEN
CLOSE io_cursor;
END IF;
--REVIRE: EXCEPTION HANDLER
END select_A1001310;
So if it helps anyone, I resolved my issue by specifying the OUT parameter declared in the procedure. This resulted in me changing from Oledb to OracleClient as follow:
public static DataTable SearchClient()
{
string connection = ConfigurationManager.ConnectionStrings["DBConnection_Oracle"].ToString();
string procedure = packetName + ".p_search_client";
OracleParameter[] parameters = new OracleParameter[1];
parameters[0] = new OracleParameter("io_cursor", OracleType.Cursor, 4000, ParameterDirection.Output, true, 0, 0, "", DataRowVersion.Current, String.Empty);
DataTable dt = new DataTable();
dt = DataManager_Oracle.GetDataTable_(connection, procedure, parameters);
return dt;
}
It seems that on the Website environment it didn't like leaving out the OUT parameter; whereas on the WebApplication I did not specify it, and it worked just fine... If some one know the why , PLEASE let me know :)
I am creating a Web API that will fetch information from a table using Entity Framework database-first approach using stored procedures. ListAllTeams_Result is the complex type object created in Entity Framework. I am looping through the import function GetAllTeams() and populating the complex type. I am getting an error in my business layer when trying to access the data access layer
The error that I am getting is the following code
var team = _teamRepository.GetAllTeams();
The result of the query cannot be enumerated more than once.
Note: this error is in the inner stack and doesn't stop the application from executing
foreach (var t in team)
Calling 'Read' when the data reader is closed is not a valid operation.
Note : This stops execution
Business Layer
public IEnumerable<TeamDto> GetTeam()
{
var team = _teamRepository.GetAllTeams();
if (team != null)
{
foreach (var t in team.ToList())
{
yield return Mapper.Map<TeamDto>(t);
}
}
yield break;
}
DataAccess layer:
public IEnumerable<ListAllTeams_Result> GetAllTeams()
{
using (var mcrContext = new MCREntities())
{
return (from team in mcrContext.ListAllTeams("")
select new ListAllTeams_Result
{
TeamID = team.TeamID,
TeamDescription = team.TeamDescription,
CountryCode = team.CountryCode,
CreatedBy = team.CreatedBy,
CreatedDate = team.CreatedDate,
ModifiedBy = team.ModifiedBy,
ModifiedDate = team.ModifiedDate
});
}
}
I have found what the problem is. I had to add ToList in the return
using (var mcrContext = new MCREntities())
{
return (from team in mcrContext.ListAllTeams("")
select new ListAllTeams_Result
{
TeamID = team.TeamID,
TeamName = team.TeamName,
TeamDescription = team.TeamDescription,
CountryCode = team.CountryCode,
CreatedBy = team.CreatedBy,
CreatedDate = team.CreatedDate,
ModifiedBy = team.ModifiedBy,
ModifiedDate = team.ModifiedDate
}).ToList();
}