Techniques for handling requests for data at a cache

1. A method, comprising:

receiving, at an in-memory cache of a computer system, a request from an application for particular data, wherein the request passes in a class having a function executable to access the particular data from a location external to the in-memory cache in response to a cache miss;

handling, at the in-memory cache, the request such that the cache miss is not returned to the application, wherein the handling includes:

determining whether the in-memory cache stores the particular data;

in response to determining that the in-memory cache does not store the particular data:

calling the function of the class passed in by the request to access the particular data from the location external to the in-memory cache;

receiving the particular data returned by execution of the function;

storing the particular data in the in-memory cache; and

returning the particular data in response to the request; and

invalidating, at the in-memory cache, data returned by execution of the function in response to determining that the function included in the class has been modified.

2. The method of claim 1 , further comprising:

calling another function of the class to determine whether data in the in-memory cache has been stored for an interval of time that satisfies a staleness threshold; and

in response to determining that a portion of the data in the in-memory cache has been stored for an interval of time that satisfies the staleness threshold, invalidating the portion of the data.

3. The method of claim 1 , wherein the particular data is stored in the in-memory cache based on a key, and the method further comprising:

generating the key based on a value corresponding to the class passed in by the request and a hash of variables passed to the function.

4. The method of claim 1 , further comprising:

after storing the particular data in cache, receiving an additional request for the particular data, wherein the additional request passes in the class; and

returning the particular data in response to receiving the additional request without calling the function of the class passed in by the additional request.

5. The method of claim 1 , wherein the request includes variables usable to generate a query for accessing the particular data from a database at the external location, and wherein the particular data is stored in the in-memory cache in association with the variables.

6. The method of claim 1 , wherein the function of the class is stored outside of the in-memory cache, and wherein the external location is a database of the computer system.

7. A non-transitory, computer-readable medium having program instructions stored thereon that are capable of causing a database system to perform operations comprising:

receiving a request from an application for requested data stored in a cache of the database system, wherein the request passes in a class having a function that is executable to retrieve the requested data from a database;

prior to handling the request, making a particular determination on whether the function is capable of returning data when called by the database system;

determining, based on the particular determination, whether to generate a record having an indication specifying that the function is not capable of returning data, wherein the indication is displayable to a user associated with the application; and

handling the request by:

determining whether the requested data is stored in the cache;

based on determining that the requested data is stored in the cache:

returning the requested data in response to the request; and

based on determining that the requested data is not stored in the cache:

calling the function included in the class to retrieve the requested data from the database;

storing the requested data in the cache; and

returning the requested data in response to the request.

8. The computer-readable medium of claim 7 , wherein the operations further comprise:

in response to the function being modified such that a manner in which data is retrieved has changed, invalidating data in the cache that is associated with calling the function prior to the function having been modified.

9. The computer-readable medium of claim 7 , wherein the operations further comprise:

after determining that the requested data is stored in the cache, calling another function included in the class to determine whether the requested data has become stale; and

in response to determining that the requested data has not become stale, returning the requested data in response to the request.

10. The computer-readable medium of claim 7 , wherein the received request includes a set of values usable to retrieve the requested data from the database, and wherein the operations further comprise:

deriving a key based on performing a hash of the set of values, wherein the requested data is stored in the cache in association with the derived key.

11. The computer-readable medium of claim 10 , wherein data is stored in the cache based on a key-value pair scheme, wherein the determining whether the requested data is stored in the cache includes:

determining whether the requested data is stored in association with the derived key.

12. The computer-readable medium of claim 7 , wherein the operations further comprise:

prior to receiving the request from the application and in response to determining that data is to be stored in association with the class, requesting that a definition be provided for the function.

13. A method, comprising:

in response to determining that a class of an application is to store data in an in-memory cache, a computer system requesting a function executable to provide values to be stored in the in-memory cache;

verifying, by the computer system, that the class of the application includes the function in response to receiving a first request to execute the application;

receiving, by the computer system, a second request for a value from the in-memory cache, wherein the second request specifies the class of the application;

determining, by the computer system, whether the in-memory cache stores the value;

in response to determining that the in-memory cache does not store the value:

calling, by the computer system, the function of the class to access the value;

receiving, by the computer system, the value returned by execution of the function;

storing, by the computer system, the value in the in-memory cache; and

returning, by the computer system, the value in response to the second request.

14. The method of claim 13 , wherein the second request specifies a set of variables usable to access the value, and the method further comprising:

generating, by the computer system, a key used to store the value in the in-memory cache based on a hash of the set of variables, wherein the key specifies a first version associated with the class.

15. The method of claim 14 , further comprising:

in response to the class being updated to a second version, the computer system invalidating values in the in-memory cache that correspond to keys specifying the first version.

16. The method of claim 13 , further comprising:

calling, by the computer system, an additional function to determine values in the in-memory cache that have become stale; and

invalidating, by the computer system, the determined values.

17. The method of claim 13 , further comprising:

calling, by the computer system, an additional function to determine a value in the in-memory cache to be replaced by the received value; and

storing, by the computer system, the received value in place of the determined value in the in-memory cache.

18. The method of claim 13 , wherein the determining that a class of an application is to store data in the in-memory cache is based on the class implementing an interface having a signature for the function.