c++ - QODBC SQL timeout -

-

i have c++ qt application running on many devices, needs communicate ms sql server. i'm using qodbc3 (unixodbc) driver.

the sql connection once initialized , connected , used repeatedly. this, query runs fast (max 20ms).

everythink works fine when there no connection issue. when network connection lost short time, sql connection can not "reconnect".

i tried check if connection on before each query attempt, qsqldatabase::isopen() returns true unless close() called. not change after network issue. in oppinion, best way setting timer in odbc driver short time , try reconnect when timeout goes off. timeout in odbc set cca 15 minutes , not able set different value.

sqlconnection.setconnectoptions("sql_attr_connection_timeout=5");

this command seems change nothing, tried complete nonsense in string, no error or something.

my next try ping server every time before running query, if network connection on again, ping goes true , sql connection still broken.

my "temporary" solution open sql connection before each query , close afterwards (with ping preceding opening). solution prolongs each query cca 500ms , not realy happy it.

four possible solutions side:

  • succesfully set timeout in odbc driver
  • implement own timeout in higher level above qsqldatabase
  • detect network issues before trying run sql query
  • keep temporary solution , pretend can not changed :-(


Comments

Post a Comment

Popular posts from this blog

Spring Boot + JPA + Hibernate: Unable to locate persister -

-
i trying work entity inside request method of spring boot application. entity in project , pom.xml has dependencies it. why error message?: org.hibernate.unknownentitytypeexception: unable locate persister: com.ric.bill.model.bs.par package com.ric.web; import java.util.concurrent.atomic.atomiclong; import javax.persistence.entitymanager; import javax.persistence.persistencecontext; import net.sf.ehcache.cachemanager; import net.sf.ehcache.management.cache; import net.sf.ehcache.management.cachestatistics; import org.hibernate.stat.statistics; import org.springframework.beans.factory.annotation.autowired; import org.springframework.boot.autoconfigure.domain.entityscan; import org.springframework.cache.annotation.enablecaching; import org.springframework.transaction.annotation.enabletransactionmanagement; import org.springframework.transaction.annotation.propagation; import org.springframework.transaction.annotation.transactional; import org.springframework.web.bind.annotati
Read more

go - Golang: panic: runtime error: invalid memory address or nil pointer dereference using bufio.Scanner -

-
i implementing go program uses bufio.scanner , bufio.writer have packaged code follows package main import ( "fmt" "player/command" "strings" ) func main() { //enter code here. read input stdin. print output stdout commands.scanner.scan() { //scan new line , send comand variable check command exist or not input := strings.split(strings.trim(commands.scanner.text(), " "), " ") command := input[0] if command == "" { fmt.printf("$ %s:", commands.pwd) continue } if !commands.commands[command] { commands.throwerror("cannot recognize input.") } else { commands.execute(command, input[1:], nil) } fmt.printf("$ %s:", commands.pwd) } } i using init.go file in main package follows package main import ( "flag" "player/sourc
Read more

c - double free or corruption (fasttop) -

-
this code reads null terminated string file (file containing null terminated strings & should provide index wanted string). error: *** error in `./main': double free or corruption (fasttop): 0x090a4a80 *** aborted code: char *tmp_realloc=null; char *sstring=null; int i=1; /*set file pointer point string*/ fseek(fh,index,seek_set); sstring=(char*)malloc(sizeof(char)); if(sstring == null) return null; tmp_realloc=sstring; while( (*(sstring+i-1)=(char)fgetc((file*)fh)) != 0x0 ) { /*reallocate more memory*/ tmp_realloc=(char*)realloc((char*)sstring,++i); /*if not same address copy old new & set old point new*/ if(tmp_realloc != sstring){ strcpy((char*)tmp_realloc,(char*)sstring); free(sstring); sstring=tmp_realloc; } } could tell me pointer causing issue (& reason) ? remove part /*if not same address copy old new & set old point new*/ if(tmp_realloc != sstring){ strc
Read more