# README

CH-Timed-Buffer

Poller for inserting rows to Clickhouse, this would wait specific time to flush inserts or when buffer full. Need modification if used with other database product.

How To Use

create a PrepareFunc = the prepared statement

prepareFunc := func(tx *sql.Tx) *sql.Stmt {
	stmt, err := tx.Prepare(`INSERT INTO dummy1(strCol,intCol,floatCol,dateCol,timeCol) VALUES(?,?,?,?,?)`)
	L.IsError(err, `failed prepare insert to dummy1`)
	return stmt
}

create timed buffer, one per prepared statement, requirement:

clickhouse connection
max buffer count (capacity), measure record size so it won't use too much memory, eg. 100K x 200 byte row = will use around 2 x 20 MB (double buffer), clickhouse can ingest 600K-1 million records per second, don't set it too low (<10K) or it would throw an error like this code: 252, message: Too many parts (300). Merges are processing significantly slower than inserts
flush interval and shutdown delay
function that create prepared statement

tb := chBuffer.NewTimedBuffer(conn, capacity, 1*time.Second, prepareFunc)

if you want to exit immediately after all flushed and exit triggered, without this, might deadlock if:

using multiple channel that depend each other
calling Close() or sending TriggerExit twice

// if this value true, any code after <- WaitFinalFlush will not be called
//   including main's defer
tb.ForceExitOnSignal = true

change default behavior from waiting remaining insert to exit immediately after flush if Close() or TriggerExit called.

// if this false (default) = you want to exit by waiting last flush ticker / no more traffic
// if this true, there will be loss data when there's pending channel queue more than buffer length or insert after close triggered
tb.DontWaitMoreInsertAfterClose = true

add callback to gracefully close other goroutine (eg. webserver) if needed, see *_test directory for example.

tb.OnExitCallback = func() {}

ignore interrupt signal

tb.IgnoreInterrupt = true

enqueue the insert

tb.Insert(...) // can be on other goroutine, it's thread safe, if insert > capacity, it would block

trigger exit manually (if needed)

tb.Close() 
tb.TriggerExit <- true // alternate syntax

make main func doesn't exit until last record flushed, should be the last on main

<- tb.WaitFinalFlush

Run tests

make test