There are three limits related to methods annotated with the ``++@future++`` keyword:

* There is a maximum number of ``++@future++`` calls allowed per transaction.
* There is a maximum number of ``++@future++`` calls allowed per organization and per a 24-hour period.
* Salesforce protects its infrastructure from organizations calling too many ``++@future++`` methods: if more than 2000 ``++@future++`` requests are queued, any additional request https://developer.salesforce.com/docs/atlas.en-us.apexcode.meta/apexcode/apex_invoking_future_methods.htm[will be delayed].

Thus it is a best practice to avoid calling ``++@future++`` methods in loops and instead call it once with all the necessary data.


See https://developer.salesforce.com/docs/atlas.en-us.222.0.apexcode.meta/apexcode/apex_gov_limits.htm[Execution Governors and Limits] for the exact number of ``++@future++`` calls allowed in each context.


This rule raises an issue when a method annotated with the ``++@future++`` keyword is called in a loop.


== Noncompliant Code Example

----
public class FutureClass {
    @future
    public static void processTaskFuture(ID taskId) {
        Task task = [SELECT Id, Subject FROM Task WHERE Task.Id = :taskId];
        task.Subject = 'new task subject';
        update task;
    }

    public static void updateUserTasks(ID ownerID) {
        List<Task> tasks = [SELECT Id, Subject FROM Task WHERE Task.ownerid = :ownerID];
        for (Task task: tasks) {
            processTaskFuture(task.Id);  // Noncompliant
        }
    }
----


== Compliant Solution

----
public class FutureClass {
    @future
    public static void processTasksFuture(List<ID> taskIds) {
        List<Task> tasks = [SELECT Id, Subject FROM Task WHERE Task.Id IN :taskIds];
        for (Task task : tasks) {
            task.Subject = 'new task subject';
        }
        update tasks;
    }

    public static void updateUserTasks(ID ownerID) {
        List<Task> tasks = [SELECT Id, Subject FROM Task WHERE Task.ownerid = :ownerID];
        List<Id> ids = new List<ID>();
        for (Task task: tasks) {
            ids.add(task.Id);
        }
        processTasksFuture(ids);
    }
----


== See

* https://developer.salesforce.com/page/Apex_Code_Best_Practices[Apex Code Best Practices]
* https://developer.salesforce.com/docs/atlas.en-us.222.0.apexcode.meta/apexcode/apex_gov_limits.htm[Execution Governors and Limits]
* https://developer.salesforce.com/docs/atlas.en-us.apexcode.meta/apexcode/apex_invoking_future_methods.htm[Future Methods]
* https://trailhead.salesforce.com/content/learn/modules/asynchronous_apex/async_apex_future_methods[Use Future Methods]

