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Mark Moore 7Mark Moore 7 

How to Eliminate @HttpPost Race Condition

This is a cross-post to salesforce.stackexchange.com.

I have a custom API that accepts incoming @HttpPost requests from third parties. The POST request inserts a new complex custom object that may contain one or more Contact records.

There is a race condition between the [SELECT Id FROM Contact WHERE LastName = :newContact.LastName].size() > 0 test and the insert newContact.

This seems like a pretty serious limitation. So, I'm hoping others have found a solution. I have read through the Apex reference, and I can't find anything to eliminate this race.

More Info:
This has turned out to be a pretty serious issue. I'm surprised no one else has run into this.  I have now modified the code to try 5 times to either insert the new record, or find the existing record.  If I try to upload records with 245 roughly simultaneous POSTs, 47 fail (fail to create or find the existing crew member Contact record).

Here is the modified code: 
private static Id StoreNewCrewMember(Contact newCrew)
{
	if (newCrew == null)
	{
		return null;
	}

	if (String.isBlank(newCrew.EMSID__c))
	{
		return null;
	}

	Integer i = 0;
	for (i = 0; i < 5; ++i)
	{
            Contact[] existingCrew = [SELECT Id FROM Contact WHERE
                                     EMSID__c = :newCrew.EMSID__c AND MailingState = :newCrew.MailingState
                                    ];
            if (existingCrew.size() > 0)
            {
                return existingCrew[0].Id;
            }

            try
            {
        	insert newCrew;
        
	        return newCrew.Id;
            }
            catch (DmlException ex)
            {
            }
	}
	
	throw new DmlException('Failed '+i+' attempts to create Crew record');
}

What am I missing?
Mark Moore 7Mark Moore 7
I am surprised at how inactive this forum seems to be.  :-(  I did not get any useful suggestions over at salesforce.stackexchange.com, but at least I got some views and replys.  Here, there's nothing but crickets.

If developer.salesforce.com/forums is this dead/useless, why not just merge the whole forum over to salesforce.stackechange and point developers there?  :-?

This is a real issue, and I'm certain this affects almost anyone exposing a REST API that allows inserting new records.

I'll comeback and update with any solution I find, but WOW this is a lame support forum.
Mark Moore 7Mark Moore 7
I continue to be stunned by how inactive this developer forum is...  Here's an update for whatever poor soul wanders these echoing halls in the future:

We paid to have Premium tech support (just at T3 (tier 3) now).  Here is a link to a "success" for a similar race condition that has a work around of "just try again":

https://success.salesforce.com/issues_view?id=a1p300000008YBEAA2

"Just try again" doesn't work for me because the crew contact collision is nested inside a parent structure.  I don't have the ability to roll back the inserts that had succeeded before the crew collision eventually fails.  I am actually shocked by how lame a work around that is.

I'm hoping T3 or someone in the Salesforce developer community knows how to implement a manual atomic test-and-set (SELECT-and-insert).

At least now I know I'm not the only guy with this issue. <sigh>