CODEWITHSUNDEEP
firebasecachingfirebase-realtime-databasegoogle-cloud-functions
Vikas Patel
Vikas Patel

Reputation: 21

Firebase Functions: Support Global variable across functions

I want to cache most recent records (say last 24 hrs) in a http firebase function. In a http firebase function (say fetchLastXRecords), I look for the record in cache (defined Global variable to store the records) if not found fetch from database and set cache.

Problem arises when I want to update any record of cache because this Global variable is not accessible by other firebase functions (could be real time database change triggers).

What could be a good approach to update the records in cache? May be I can invoke the caching http firebase function and pass the updated records? or I can store the updated records in database and later caching function look in database and update the cache records?

Upvotes: 2

Views: 4253

Answers (1)

Doug Stevenson
Doug Stevenson

Reputation: 317372

In Cloud Functions, you have no ability to ensure that there is a global variable in your code that's accessible by your functions. There are two things you need to know about how Cloud Functions works:

  1. Under load, multiple server instances will be allocated to run your functions. These server instances don't share any state.
  2. Each of your functions is deployed to different server instances. Two functions will never run on the same server instance.

As a result, if you have any values to share between functions, you should use a persistence mechanism, such as a database. When your functions need to read and write a shared value, they should access the database. Also, they should use some sort of atomic transaction to make sure that multiple concurrent reads and writes are safe.

Upvotes: 14

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