How to update the value of a Key in ObjectStore in Mule4?

Question

My requirement is, i need to count messages which are processed for a day. So, i created a subflow, where I created a persistent objectstore . I retrive it initially with the default value 0. Then , I pass that to java AtomicInteger class to do increment each time, when request comes in. Now I store the new value.

    <sub-flow name="impl-message-counter:\counter-set-flow" doc:id="929c5fa5-74a2-4e8e-b1a0-43209b57222c" >


   <os:retrieve doc:name="Retrieve" doc:id="565ecf6c-ffba-491e-b2c9-35ef4b4f52ad" key="counter" objectStore="Object_store" target="count">
            <os:default-value ><![CDATA[0]]></os:default-value>
        </os:retrieve>
            <java:new constructor="AtomicInteger(int)" doc:name="New" doc:id="f0e75c0b-914a-44ee-9e24-a597025afd77" class="java.util.concurrent.atomic.AtomicInteger" target="atomicinteger">
                <java:args ><![CDATA[#[output application/java
    ---
    {
    arg0 : vars.count as Number {class: "java.lang.Integer"}
    }]]]></java:args>
            </java:new>
            <java:invoke doc:name="Invoke" doc:id="60779082-ad71-4770-b871-8d86044aa62a" instance="#[vars.atomicinteger]" class="java.util.concurrent.atomic.AtomicInteger" method="incrementAndGet()" target="newVal"/>
        <os:store doc:name="Store" doc:id="8f85aa4f-5bce-4248-8a3b-a8cde27a1307" key="counter" objectStore="Object_store">
            <os:value><![CDATA[#[vars.newVal]]]></os:value>
        </os:store> 

        </sub-flow>

In the above flow, i want to add a check processor, to see the day is passed or not. If it passes midnight I wnat to reassign it to 0. Else continue with increment;

<choice doc:name="Choice" doc:id="120b1f05-7afe-4cfc-a103-0b26f9df7140" >
            <when expression="#[now().hour==23 and now().minutes==59 and now().seconds==60]">
                <os:store doc:name="Store" doc:id="3d995b22-a648-4c7f-af54-33d70b23705c" key="counter" objectStore="Object_store" >
                    <os:value ><![CDATA[#[0]]]></os:value>
                </os:store>
            </when>
            <otherwise >
                <os:store doc:name="Store" doc:id="8f85aa4f-5bce-4248-8a3b-a8cde27a1307" key="counter" objectStore="Object_store">
            <os:value><![CDATA[#[vars.newVal]]]></os:value>
        </os:store>
            </otherwise>
        </choice>

But above will work? I think it will skip if same key present in same objectstore? How can I update existing key?

Answer 1

This is good idea but you have to be aware that object store is unreliable. You can check it if you write a simple test and do load and stress test. Especially in cluster. First and usually it works but later and especially on concurrent requests at the same moment it fails. So, use it if with caution and do not rely on it. Worst part - it will break you flow. What we can do is - https://simpleflatservice.com/mule4/IgnoreUnreliableObjectStorage.html - wrapping every single call to object store to try block and simply ignore any failure or unexpected results.

Here is code

<?xml version="1.0" encoding="UTF-8"?>

<mule xmlns:http="http://www.mulesoft.org/schema/mule/http" xmlns:ee="http://www.mulesoft.org/schema/mule/ee/core"
    xmlns:os="http://www.mulesoft.org/schema/mule/os"
    xmlns="http://www.mulesoft.org/schema/mule/core" xmlns:doc="http://www.mulesoft.org/schema/mule/documentation" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.mulesoft.org/schema/mule/core http://www.mulesoft.org/schema/mule/core/current/mule.xsd
http://www.mulesoft.org/schema/mule/os http://www.mulesoft.org/schema/mule/os/current/mule-os.xsd
http://www.mulesoft.org/schema/mule/ee/core http://www.mulesoft.org/schema/mule/ee/core/current/mule-ee.xsd
http://www.mulesoft.org/schema/mule/http http://www.mulesoft.org/schema/mule/http/current/mule-http.xsd">
    <flow name="selftestFlow" doc:id="79a89806-adea-4017-a838-8b8c3e2002df" >
        <http:listener doc:name="Listener" doc:id="63128e3f-34f5-4f04-9b8a-0bebe67f763c" config-ref="HTTP_Listener_config" path="/counter"/>
        <try doc:name="Try" doc:id="d5d83aa3-b271-41b0-98a6-381823164de4" >
            <os:retrieve doc:name="Retrieve" doc:id="f6d3cccd-a7be-44fa-a51d-36bddbc5892f" key="test" target="localTest">
            <os:default-value><![CDATA[N/A]]></os:default-value>
        </os:retrieve>
            <error-handler >
                <on-error-continue enableNotifications="true" logException="true" doc:name="On Error Continue" doc:id="b14ab2e4-c871-4af8-a488-9c70284a525f" />
            </error-handler>
        </try>
        <ee:transform doc:name="Transform Message" doc:id="bc50c855-34b4-4661-9f42-2b18e441782d" >
            <ee:message >
            </ee:message>
            <ee:variables >
                <ee:set-variable variableName="localTest" ><![CDATA[%dw 2.0
output application/java
---
if (vars.localTest is Number) ( vars.localTest as Number + 1 ) else ( 1 as Number )]]></ee:set-variable>
            </ee:variables>
        </ee:transform>
        <try doc:name="Try" doc:id="2d54c616-7fb6-41ba-bc05-0918199bcba4" >
            <os:store doc:name="Store" doc:id="2847d9db-d2f6-4bc4-a0a5-dca0eafbdd49" key="test">
            <os:value><![CDATA[#[vars.localTest]]]></os:value>
        </os:store>
            <error-handler >
                <on-error-continue enableNotifications="true" logException="true" doc:name="On Error Continue" doc:id="90e6616a-af11-4af6-a82f-e9823f764ceb" />
            </error-handler>
        </try>
        <ee:transform doc:name="Transform Message" doc:id="bdc2a164-3d80-427f-b95d-a7dfc2b69400" >
            <ee:message >
                <ee:set-payload ><![CDATA[%dw 2.0
output application/json
---
{ counter: vars.localTest }]]></ee:set-payload>
            </ee:message>
        </ee:transform>
    </flow>
</mule>