小编Jam*_*mes的帖子

我目前正从EntityManager查询中获取连接超时错误.是否可以为这些设置超时？

persistence.xml中

<?xml version="1.0" encoding="UTF-8"?>
<persistence version="2.0" xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd">
  <persistence-unit name="CallPU" transaction-type="RESOURCE_LOCAL">
    <provider>org.eclipse.persistence.jpa.PersistenceProvider</provider>
    <class>call.structure.Task</class>
    <class>call.structure.Installation</class>
    <class>call.structure.Contents</class>
    <class>call.structure.Recipient</class>
    <class>call.structure.CallTask</class>
    <class>call.structure.SmsTask</class>
    <class>call.structure.EmailTask</class>
    <class>call.security.User</class>
    <class>call.structure.content.Content</class>
    <class>call.structure.content.RecordContent</class>
    <class>call.structure.content.WaitContent</class>
    <class>call.structure.content.TextContent</class>
    <class>call.structure.content.VariableContent</class>
    <class>call.structure.content.SoundContent</class>
    <class>call.structure.content.SubjectContent</class>
    <class>call.structure.content.FileContent</class>
    <class>call.structure.Bounce</class>
    <properties>
      <property name="javax.persistence.jdbc.url" value="jdbc:oracle:thin:@127.0.0.1:1521:TEST"/>
      <property name="javax.persistence.jdbc.password" value="userpassword"/>
      <property name="javax.persistence.jdbc.driver" value="oracle.jdbc.OracleDriver"/>
      <property name="javax.persistence.jdbc.user" value="username"/>
    </properties>
   </persistence-unit>
</persistence>

代码在我的线程的run函数中超时:

private class TaskDB extends Thread {

    private final long WAITING_TIME = 20000L;

    @Override
    public void run() {

        Set<SmsTask> remove = SMSManager.this.getRemoveTask();
        Set<SmsTask> normal = SMSManager.this.getNormalTask();

        try {
            while(true){
                EntityManager em = …

在C ++中，建议使用lock_guard，因为它可以确保在销毁对象时将互斥体解锁。

有没有办法在C中实现相同的功能？还是我们必须手动实现它：

锁定互斥

在全局变量上做某事

解锁互斥锁

#include <stdio.h>
#include <threads.h>

long long x = 0;
mtx_t m;
static void do1()  {
   mtx_lock(&m); 
   for(int i = 0; i < 100; i++){
       x = x +1;
   }
   mtx_unlock(&m);
}

static void do2()  {
   mtx_lock(&m); 
   x = x / 3;
   mtx_unlock(&m);
}

int main(int argc, char *argv[])
{ 
   mtx_init(&m, mtx_plain);
   thrd_t thr1; 
   thrd_t thr2;
   thrd_create(&thr1, do1, 0);
   thrd_create(&thr2, do2, 0);
   thrd_join(&thr2, 0);
   thrd_join(&thr1, 0);
   return 0;
}